Cancer Letters

Published by Elsevier
Print ISSN: 0304-3835
Publications
1 M Tegafur (FT)-0.4 M 5-chloro-2,4-dihydroxypridine (CHDP)-1 M potassium oxonate (Oxo) (S-1), was developed as a new oral antineoplastic agent based on biochemical modulation of fluorouracil (5-FU) by CHDP and Oxo. The antitumor effect of S-1 on human head and neck squamous carcinoma cells was evaluated in xenografts and a metastasis model, in comparison with combined drug of 1 M FT and 4 M uracil (UFT). Mice treatment with S-1 showed a significant higher concentration of 5-FU in the tumor and the serum than UFT treated mice. S-1 showed higher tumor growth inhibition and metastasis inhibition than UFT. The mice in which metastasis was inhibited lived more than twice as long as the control mice. These results suggest that S-1 will have a higher clinical therapeutic effect against advanced squamous cell carcinoma of the head and neck in humans.
 
The hypercalcaemic Walker carcinosarcoma 256 is a rat model for humoral hypercalcaemia of malignancy (HHM). Tumour products such as parathyroid hormone-related proteins (PTHRP) and various growth factors appear to be responsible for this syndrome. Recently, PTHRP immunoreactivity has been detected in the conditioned medium of Walker tumour cells. The present report describes the isolation of a 18,000-Da molecular weight form of PTHRP from Walker tumour homogenates, by using a relatively simple immunoaffinity purification method. Our results suggest that this PTHRP form is similar to that purified from other HHM-related tumours.
 
Aberrant hypermethylation of gene promoter regions is one of the mechanisms for inactivation of tumour suppressor genes in breast cancer. We investigated whether hypermethylation identifies breast cancers with distinctive clinical and pathological features. We evaluated the methylation of RARbeta2, CDH1, ER, BRCA1, CCND2, p16 and TWIST in 193 breast carcinomas. Methylation frequencies ranged from 11% for CCND2 to 84% for ER. Tumours with frequent methylation (4-6 genes) were more often poorly differentiated compared to those with infrequent methylation (0-2 genes; P=0.004). Tumours with ER and CDH1 methylation were associated with significantly lower hormone receptor levels, younger age at diagnosis and the presence of mutant p53. Our data suggests that gene methylation may be linked to various pathological features of breast cancer, however, this requires confirmation in larger studies.
 
RT-PCR analysis of mdr1 gene expression. 1, PCR marker; 2, KB cells; 3, KB cells; 4, KBr cells. The DNA fragments of the PCR marker are 1543, 994, 695, 515, 377 and 237 base pairs. The KB cell line was used as a positive control for mdr1 gene expression.
We induced tolerance to hexadecylphosphocholine (HePC) in the human epidermoid tumor cell line, KB. After 70 weeks of adaptation, the IC50 of HePC in the resistant cells KBr was 32-fold higher than in parental KB cells, and they were 30-fold more resistant to another ether lipid analogue, ET-18-OCH3. The KBr cells also showed cross-resistance to vincristine and colchicine while remaining sensitive to other chemotherapy agents. RT-PCR assays showed that expression of the multidrug resistance gene (MDR1) was positive in KBr cells, whereas the expression of GST-pi (glutathione S-transferase pi) and MRP (multidrug resistance protein) was undetectable in KBr cells. Both an immunocytochemistry test and Western blot analysis indicated that the expression of bcl-2 in KBr cells was strongly positive, while it was only mildly expressed in KB cells. Verapamil could not reverse the resistance of KBr to HePC although it is a well-known reversing agent against MDR1. Our results suggest that bcl-2 instead of MDR1 plays a major role in the resistance of KBr cells.
 
We determined the cytotoxicity of AG490 as a single agent and in combination with 7-hydroxystaurosporine (UCN-01) in a panel of malignant human glioma cell lines. Because p53 has important roles in cell cycle checkpoints, it has been anticipated that modulation of checkpoint pathways should sensitize p53 defective cells while sparing the normal cells. Cell proliferation was determined from dose-response curves. AG490 was effective as a cytotoxic agent alone regardless of p53 status. Combining the Chk1 inhibitor UCN-01 dramatically enhanced the response to AG490 in p53-mutated or deleted glioma cells. An opposite effect was noted in p53-wild type cells, in which UCN-01 and AG490 had antagonistic effects on cell proliferation and viability. We found that AG490 enhanced BAD phosphorylation in p53 wild type glioma cells, which appeared to protect against UCN-01-induced cytotoxicity, whereas AG490 enhanced UCN-01-induced cytotoxicity in p53 defective cell lines by suppression of BAD phosphorylation and induction of BAX and PARP cleavage. These observations highlight the potential for genotype-dependent factors to strongly influence response to signaling-targeted therapies in malignant gliomas and the importance of considering such factors in correlative response analyses for these agents.
 
Combination of chemotherapeutic agents and angiogenesis inhibitors is now commonly employed in the clinic to treat cancer. Here, we used angiostatic agents anginex and 0118, in combination with the chemotherapeutic irofulven, to treat human ovarian tumor xenografts in mice. General linear mixed models were used to statistically analyze tumor growth curves. Overall, combination of a low, non-toxic dose of irofulven with either angiogenesis inhibitor was more effective at inhibiting tumor growth than any of the single agent therapies. For example, the anginex/irofulven and 0118/irofulven combinations inhibited tumor growth relative to controls by 92% (p<0.0001) and 96% (p<0.0001), respectively, with the 0118/irofulven combinations yielding 100% complete responses. This study suggests that combination therapy of 0118 or anginex and irofulven may be highly effective in the clinical setting.
 
HCA661 is a cancer-testis (CT) antigen frequently expressed in human hepatocellular carcinoma (HCC). To search for immunogenic peptides of HCA661, bioinformatics analysis and CD8(+) T cell IFN-gamma ELISPOT assay were employed, and two HLA-A *0201 restricted peptides, H110 and H246, were identified. These two HCA661 peptides are naturally processed in dendritic cells (DCs) and when used for DCs loading, they are sufficient to prime autologous CD8(+) T cells to elicit cytotoxic response against HCA661(+) human cancer cells. The HCA661 peptides, H110 and H246, are hence attractive candidates for human cancer immunotherapy.
 
A large number of human tumor-associated antigen-derived peptides have been identified that are recognized by CTLs in a MHC-I restricted fashion. The apoptosis inhibitory protein Bcl2 is overexpressed in many human cancers as part of their neoplastic phenotype. Since inhibition or loss of Bcl2 expression might impair tumor growth and survival, this protein may serve as a rational target for vaccine-induced CTL responses. By Western blot technique, we screened a panel of established human tumor cell lines for proteins involved in the apoptotic process. Two of eight tumor cell lines, a B lymphoma (Loukes) and a colon carcinoma (CCL220) cell line showed increased Bcl2 protein expression whereas the majority of tumor cell lines expressed proapoptotic proteins. Neither fibroblasts nor peripheral blood mononuclear cells showed Bcl2 expression. An HLA-A*0201 restricted CTL epitope was deduced in silica from the amino acid sequence of the Bcl2 protein and its binding affinity for HLA-A*0201 was confirmed using a biochemical binding assay. We here demonstrate that the 9-mer peptide Bcl2(85-93) induces specific CTL reactivity in immunized C57-A2K(b) or -A2D(b) tg mice. These Bcl2(85-93) specific CTLs react with and lyse Bcl2-expressing human colon carcinoma CCL220 cells which have been transfected with a chimeric HLA-A*0201/H2-K(b) DNA construct similar to that expressed in the transgenic mice. Based on these observations, we suggest that Bcl2(85-93) may be a target for immune therapy.
 
Human epidermal growth factor receptor 2 (HER2), a member of the HER family of tyrosine kinases and a binding partner of Heat shock protein 90 (Hsp90), is found amplifies in approximately 25% breast cancers. Treatment of HER2+ breast cancers has been greatly improved in recent years, but the accompanying upregulation of HER3 induced by HER2 blockade has subdued the therapeutic effect. FW-04-806, a novel Hsp90 N-terminal inhibitor that disassociates the Hsp90/Cdc37/client complex and degrades Hsp90 clients, was studied alone or in combination with the EGFR/HER2 tyrosine kinase inhibitor lapatinib in HER2+ breast cancer cells. We found that FW-04-806 alone or with laptinib inhibits cell proliferation, induces cell apoptosis and reduces the total and activated HER3 levels in these cells, while lapatinib has been reported to increase HER3 expression followed HER2 inhibition. The combination of FW-04-806 and lapatinib showed synergistic reduction of HER2 expression and the downstream PI3K/Akt and Ras/MEK/ERK pathways, enhanced suppression of Akt-mediated FOXO3a inactivation and augmented antitumor efficacy on SKBR3 xenografts with a favorable toxicity profile, suggesting its viability as a combination therapy for clinical studies in HER2+ breast cancer patients. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
 
The newly designed pyridine derivative B9309-068 and a series of structurally different compounds were tested for their ability to modulate rhodamine 123 (RHO) efflux from CD56+ hematopoietic cells in the presence of either 10% fetal calf serum or undiluted human AB serum. Furthermore, efflux modulation was investigated on CD34+ blast populations obtained from four patients with relapsed state AML. Target cells were specified throughout by labeling with peridinine chlorophyll protein (PerCP)-conjugated monoclonal antibodies, allowing clear differentiation from RHO emission spectrum by flow cytometry. In the presence of low serum each compound efficiently modulated RHO efflux without significant differences in the range of final concentrations (1.0-3.0 microM). At 0.1 microM, however, RHO efflux was differentially modulated following the series GF120918 approximately B9309-068 > PSC 833 > DNIG approximately DVER. With CD56+ cells in the presence of undiluted human AB serum at a final modulator concentration of 0.1 microM, all chemosensitizers tested were found to be inefficient. At final concentrations of 0.3 microM or higher, distinct RHO efflux modulation was found with the following efficacies: B9309-068 approximately GF120918 > PSC 833 > DVER approximately DNIG. The efficacies seen in undiluted human AB serum at 3.0 microM were comparable to those seen on CD56+ cells at final modulator concentrations of 0.1 microM in low serum. Our results identify the pyridine derivative B9309-068 as a promising compound for modulating P-glycoprotein-mediated drug resistance under conditions resembling the clinical setting. Nonetheless, modulation potencies of a series of structurally very different chemosensitizers was revealed to be substantially diminished at high serum concentrations in vitro.
 
In this study, we explored the antitumor activities of the PARP inhibitor AZD2281 (Olaparib) and the pan-Bcl-2 inhibitor GX15-070 (Obatoclax) in six pancreatic cancer cell lines. While both agents were able to cause growth arrest and limited apoptosis, the combination of the two was able to synergistically cause growth arrest and non-apoptotic cell death. Furthermore, in an in vivo xenograft model, the combination caused substantially increased tumor necrosis compared to either treatment alone. Our results support further investigation of the combination of Bcl-2 and PARP inhibitors for the treatment of pancreatic cancer.
 
Despite improvements in both surgical techniques and radio- and chemo-therapy regimens, the prognosis of esophageal cancer is poor. In pursuit of novel effective strategy, this study examined the effect of the BH3-mimetic GX15-070 on esophageal carcinoma cells. We discovered that GX15-070 inhibited the growth of esophageal cancer cells. There was synergism between GX15-070 and carboplatin or 5-fluorouracil. GX15-070 induced autophagy in esophagus cancer cell line EC9706 and osteosarcoma cancer cell line U2OS. 3-methyladenine and chloroquine, inhibitors of autophagy with distinct mechanisms, potentiated the cytotoxicity of GX15-070. In conclusion, GX15-070 inhibits growth of esophageal cancer cells.
 
This is a preclinical study of BO-0742, a derivative of 3-(9-acridinylamino)-5-hydroxymethyl-aniline (AHMA) and N-mustard, as an anti-cancer agent. MTS assays revealed a broad spectrum of anti-cancer activities in vitro, with the greatest cytotoxicity against leukemia and neuroblastoma including those with drug resistant characteristics, and a good therapeutic index with leukemia being 10-40 times more sensitive to BO-0742 than hematopoietic progenitors. Administration of BO-0742 at an optimal dose schedule based on its pharmacokinetics significantly suppressed the growth of xenografts of human breast and ovarian cancers in mice. Thus, BO-0742 is a potent anti-cancer agent worthy of further clinical development.
 
Mortalin is a chaperone protein that functions in many cellular processes such as mitochondrial biogenesis, intracellular trafficking, cell proliferation and signaling. Its upregulation in many human cancers makes it a candidate target for therapeutic intervention by small molecule drugs. In continuation to our earlier studies showing mortalin as a cellular target of MKT-077, a mitochondrion-seeking delocalized cationic dye that causes selective death of cancer cells, in this work, we report that MKT-077 binds to the nucleotide-binding domain of mortalin, causes tertiary structural changes in the protein, inactivates its chaperone function, and induces senescence in human tumor cell lines. Interestingly, in tumor cells with elevated level of mortalin expression, fairly low drug doses were sufficient to induce senescence. Guided by molecular screening for mortalin in tumor cells, our results led to the idea that working at low doses of the drug could be an alternative senescence-inducing cancer therapeutic strategy that could, in theory, avoid renal toxicities responsible for the abortion of MKT-077 clinical trials. Our work may likely translate to a re-appraisal of the therapeutic benefits of low doses of several classes of anti-tumor drugs, even of those that had been discontinued due to adverse effects.
 
The present study showed that GDC-0941 potently sensitized breast cancer to ABT-737 in vitro and in vivo. ABT-737 exhibited limited lethality in breast cancer cells; however, when combined with GDC-0941, it displayed strong synergistic cytotoxicity and enhanced caspase-mediated apoptosis. GDC-0941 promoted proteasomal degradation of Mcl-1, of which the overexpression has been validated to confer ABT-737 resistance, thereby enhanced the anticancer efficacy of ABT-737. Furthermore, the combination of GDC-0941 and ABT-737 exerted increased anti-tumor efficacy on MDA-MB-231 xenograft models. Overall, our data described unprecedentedly the promising therapeutic potential and underlying mechanisms of combining GDC-0941 with ABT-737 in treating breast cancer.
 
Three groups of 6 rats were treated with cisplatin (3 mg/kg, bolus and 3-h infusion) and spiroplatin (3 mg/kg, bolus) by infusion in the right external jugular vein. The mean amounts of platinum +/- c.v. excreted in the bile during the first 6 h after the start of administration were 0.32 +/- 0.19% and 0.39 +/- 0.29% of the dose after bolus injection and 3-h infusion of cisplatin, respectively, and 3.77 +/- 3.32% of the dose after spiroplatin. The values were not significantly different between the 2 cisplatin administration modes (P greater than 0.05), but were between the spiroplatin and cisplatin bolus groups (Wilcoxon two-sided rank test, P less than 0.01). These data are related to pharmacokinetic parameters in man.
 
1,1-Bis(3'-indolyl)methane (DIM) and the 5,5'-dibromo ring substituted DIM (5,5'-diBrDIM) inhibited growth of MCF-7 and MDA-MB-231 breast cancer cells, and IC50 values were 10-20 and 1-5 microM, respectively, in both cell lines. DIM and 5,5'-diBrDIM did not induce p21 or p27 protein levels or alter expression of Sp1 or Sp3 proteins in either cell line. In contrast, 10 microM 5,5'-diBrDIM downregulated cyclin D1 protein in MCF-7 and MDA-MB-231 cells 12 and 24 h after treatment. DIM (20 microM) also decreased cyclin D1 in MCF-7 (24 h) and MDA-MB-231 (12 h), and the DIM/5,5'-diBrDIM-induced degradation of cyclin D1 was blocked by the proteasome inhibitor MG132. Both DIM and 5,5'-diBrDIM induced apoptosis in MCF-7 cells and this was accompanied by decreased Bcl-2, release of mitochondrial cytochrome c, and decreased mitochondrial membrane potential as determined by the red/green fluorescence of JC-1. DIM and 5,5'-diBrDIM induced extensive necrosis in MDA-MB-231 cells; however, this was accompanied by decreased mitochondrial membrane potential primarily in cells treated with 5,5'-diBrDIM but not DIM. Thus, DIM and 5,5'-diBrDIM induce cell death in MCF-7 and MDA-MB-231 cells by overlapping and different pathways, and the ring-substituted DIM represents a novel class of uncharged mitochondrial poisons that inhibit breast cancer cell and tumor growth.
 
A rate of up to 43% of malignant peripheral nerve sheath tumors (PNST) was induced in European hamsters (EH) after weekly s.c. administration of 1,1-dimethylhydrazine (UDMH). The overall neoplastic response in the treated EH was also elevated as compared to the untreated controls. Histologically, the malignant PNST were neurofibrosarcomas and melanotic as well as unpigmented schwannomas. The occurrence of melanotic schwannomas is briefly discussed with regard to the histogenesis of this rare tumor type.
 
1,1-Diethyl-3-methyl-3-nitrosourea (Et2MNU) was subcutaneously injected in Syrian golden hamsters once weekly for 52 weeks. The animals developed mainly papillomas and squamous cell carcinomas of the nasal cavity and forestomach and hemangioendotheliomas of the spleen. Although survival time and tumour latency showed dose-dependency, tumour incidence did not.
 
Tumour cell attachment to the endothelial cell lining of the circulatory system is of utmost importance in the process of cancer spread. We describe here a method of quantifying tumour cell attachment to an endothelial cell layer in vitro, using the fluorescent carbocyanine dye, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine (DiI). We show that by incubation of human tumour cells with this fluorochrome, a high degree of fluorescent label can be incorporated into the cells without cytotoxic effects. These labelled tumour cells can then be used in subsequent attachment assays involving confluent human endothelial cell layers and subsequently quantified by using a fluorescent plate reader. Monitoring of this assay by fluorescent microscopy showed no transfer of the dye between tumour and attached endothelial cells. The labelled cells remained fluorescent for more than 3 days with no observable cytotoxicity. We suggest that DiI is of use in an assay system such as this to determine the effects of various factors on tumour cell-endothelial cell attachment.
 
N-Nitrosodiethanolamine (NDEA) and 1,1-diethanolhydrazine (DEH) were synthesized and injected subcutaneously weekly in male and female Syrian golden hamsters. The total NDEA dose per hamster was approx. 15 g/kg body wt. applied in either 7 or 27 subdoses. DEH was administered in 78 applications to two groups yielding total doses of 1.1 g and 273 mg/kg body wt. Under these conditions, DEH did not show a specific demonstrable carcinogenic effect. However, within 78 weeks after the first application, 39 out of 56 hamsters treated with NDEA developed tumors. Primarily, neoplasms of the nasal cavity and tracheal tumors were observed, as well as a few hepatocellular adenomas and sarcomas at the injection site. These findings and those of the earlier study on carcinogenicity of NDEA in rats raise concern as to the safety for human consumption or industrial use of products with the potential for forming NDEA.
 
To clarify the suitability of a newborn-mouse carcinogenesis assay to detect tumor-promoting activities of carcinogens, the non-genotoxic hydroquinone (HQ) and genotoxic 1,1-dimethylhydrazine (UDMH) were administered to mice during the promotion stage after treatment with 1-methyl-1-nitrosourea (MNU) (20 mg/kg body wt, single intraperitoneal injection) at day 9 after birth. Initiated males and females thus received either HQ at 0.8% in basal diet, or UDMH, at 20 mg/kg body wt once weekly by subcutaneous injection, from day 14 until the end of the experiment at 30 weeks of age. Uninitiated newborn mice, given an injection of the vehicle (0.01 M citrate buffer (pH 5.5), 20 mg/kg body wt), also received HQ or UDMH in the same way. Histopathologically, focal proliferative lesions were found in the livers of male mice and in the lungs of both male and female mice in the MNU-treated groups. HQ significantly increased the incidence and multiplicity of altered hepatocellular foci, the combined incidence of hepatocellular adenomas and carcinomas in males and the incidence and multiplicity of lung adenomas and the combined incidence of lung adenomas and carcinomas in female mice. In addition, four out of eleven MNU + HQ-treated male mice developed lung carcinomas, showing a significant elevation in multiplicity. UDMH also exhibited a tendency to increase the incidence and multiplicity of lung adenomas in female mice. Thus tumor-promoting effects of HQ or UDMH were apparently exerted in the target organs and the MNU-initiated two-stage newborn-mouse carcinogenesis assay may be useful for detection of genotoxic or non-genotoxic carcinogenicity.
 
Aqueous solutions of the cisplatin analog aqua(1,1-bis(aminomethyl)-cyclohexane)sulfatoplatinum(II) (TNO-6, spiroplatin) principally contain hydrolyzed and oligomerized molecules. Sodium sulfate reduces the hydrolysis of the sulfato ligand. We investigated the influence of the equilibrium state on nephrotoxicity of spiroplatin in rats receiving 3 doses of 3 mg/kg with an interval of 8 days. Rats (n = 6) treated with spiroplatin solubilized in isoosmotic sodium sulfate (impaired hydrolysis) showed less toxicity as measured by proteinuria, platinum excretion and body weight, than the group treated with spiroplatin solubilized in 5% glucose. This result indicates that the presence of hydrolysis products plays a role in the toxicity of spiroplatin.
 
Comparative analysis of the cytotoxicity, transformation efficiency, induction of alkali labile sites (ALS) and DNA methylation in human foreskin fibroblasts was carried out with two dimethylhydrazine (DMH) regioisomers (1,1-DMH and 1,2-DMH) and the acetate (A) derivative of the metabolite methylazoxymethanol (MAM) of 1,2-DMH. Effective ED50 cytotoxic doses for MAMA, 1,1-DMH and 1,2-DMH were 0.056, 6.83 and 6.30 mM, respectively. MAMA and 1,1-DMH were more effective transformers than 1,2-DMH. However, methylation of purines accounted for less than 1% of the total radiolabel associated with DNA for all 3 agents. 1,2-DMH, 1,1-DMH and MAMA induced O6MeGua/N7MeGua ratio of 0.04, 0.32 and 0.18, respectively. Only MAMA induced measurable alkali labile lesions at transforming doses. These results suggest that other mechanisms may play a role in the initiation of transformation events by hydrazine analogues.
 
A dose dependent inhibition of intercellular communication (metabolic cooperation) between primary cultures of rat liver hepatocytes and an established adult rat liver epithelial cell 6-thioguanine resistant strain by the liver tumor promoter 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) is demonstrated. This in vitro assay is proposed to evaluate the tumor promoting activity of oncogenic agents shown to be non-genotoxic in the liver culture systems.
 
Data derived from studies with vinylidene chloride (1,1-dichloroethylene)and 1,1,2-trichloroethylene suggest that similar mutagenic and tumorogenic properties in mice may be attributable to rearrangement of the 2 haloalkene-derived haloepoxides, respectively, into chloroacetyl chloride and dichloroacetyl chloride. On the other hand, the relative harmlessness of 1,1,2-trichloroethylene in rats and man is due to alternative rearrangement of 1,1,2-trichloroethylene oxide into chloral and the further products of its metabolism. The identification in mice of the new 1,1,2-trichloroethylene metabolite, dichloroacetic acid (in addition to trichloroacetic acid) strongly supports this supposition. The small proportion of dichloroacetic acid in relation to the large proportion of trichloroacetic acid in the urine of the treated mice is consistent with a spill-over model that is now tentatively proposed for 1,1,2-trichloroethylene metabolism in these animals.
 
By using in vitro two-stage BALB/c 3T3 cell transformation assay, we have tested the effect of promoting treatment with tetradecanoylphorbol acetate (TPA) on transformation induced by 1,1,2,2-tetrachloroethane (1,1,2,2-TTCE). Cells were treated with subeffective or transforming concentrations of 1,1,2,2-TTCE in the presence of an S9-mix activating system, followed by TPA promoting treatment. The transforming activity of 1,1,2,2-TTCE is evident only by reseeding confluent cells and allowing additional rounds of cell replications in the amplification test. Treatment with TPA leads to a marked transformation yield in all plates scored even at the lowest assayed dosage of 1,1,2,2-TTCE, without performing amplification of transformation.
 
The direct mutagenic activity of 1,1,2,3- tetrachloropropene and 1,1,2,3,3- pentachloropropene in Salmonella typhimurium was measured before and after incubation in the presence of intact segments of rat small intestine in vitro. The number of revertants in tester strain TA100 was reduced by about 95% when these chloropropenes were exposed to rat small intestine for 10-30 min immediately prior to determination of mutagenicity. The existence of an intestine-mediated detoxication reaction was postulated, and was supported by observations that incubation with the chloropropenes for 30 min caused a 48-68% depletion of intestinal glutathione in vitro. Although addition of glutathione to the chloropropenes reduced mutagenicity, the amount of tissue glutathione consumed during incubation of mutagen with intestinal segments is probably insufficient to account for the detoxication. Additional metabolic reactions and/or non-specific protein binding may occur in the intact intestine which contribute to the antimutagenic effect. These initial results support the existence of an effective detoxication mechanism by the small intestine which is likely to reduce the absorption of direct-acting mutagens and other electrophiles.
 
The chemotherapeutic potential of 1,10-phenanthroline (phen), and three of its transition metal complexes, namely [Cu(phen)(2)(mal)]x2H(2)O, [Mn(phen)(2)(mal)]x2H(2)O and [Ag(2)(phen)(3)(mal)]x2H(2)O (malH(2)=malonic acid) was determined using two human carcinoma cell lines (A-498 and Hep-G2). Phen and the three metal-phen complexes induced a concentration-dependent cytotoxic effect, with metal complexes demonstrating the greatest cytotoxic response. In comparative studies, IC(50) values show cytotoxicity of between 3 and 18 times greater than that observed for the metal-based anti-cancer agent, cisplatin. All of the phen-based complexes inhibited DNA synthesis which did not appear to be mediated through intercalation. Also, the potential cancer chemotherapeutic application of these compounds was seen to be enhanced by results obtained from Ames tests, which showed all of the test agents and their phase I metabolites were non-mutagenic. Taken together, these results suggest that phen and the three metal-phen complexes may have a therapeutic role to play in the successful treatment and management of cancer.
 
The formation of 1,2-diacylglycerol (DAG), a known stimulator of superoxide anion radical (O2-.) production in inflammatory cells, was assessed in murine peritoneal macrophages following treatment in vitro with tumor promoters. Addition of phorbol-12-myristate-13-acetate (PMA, 1-100 ng/ml) to resident peritoneal macrophage cultures from CD-1 female mice resulted in a 3- to 7-fold increase in [3H]DAG formation. The response was observed from 15 min to 2 h following the addition of PMA. At concentrations at which they stimulate O2-. production, PMA and other tumor promoters such as mezerein, phorbol-12,13-dibutyrate and 4-O-methyl-PMA stimulated the formation of [3H]DAG. Similar results were obtained when thioglycollate-elicited macrophages were used. Concurrent with the formation of [3H]DAG was a release of [3H]choline equivalents from the resident peritoneal macrophages treated with tumor promoters. The calcium ionophore A23187 did not stimulate O2-. production of [3H]DAG formation in resident peritoneal macrophages. These results demonstrate that tumor promoters stimulate the accumulation of DAGs in murine peritoneal macrophages at concentrations at which they stimulate O2-. production and suggest a mechanism by which tumor promoters such as mezerein, which are weak activators of protein kinase C, may indirectly stimulate O2-. production.
 
The content of cytochromes P-450 and b5 in rat liver microsomes, as well as the extent of labeling of nucleic acids and proteins of the liver and kidneys and of mucosa from different intestinal segments, was studied in rats injected daily or once a week subcutaneously with similar total doses of 1,2-dimethyl-hydrazine (SDMH) and in untreated rats. Daily SDMH administrations led to a decrease in cytochrome P-450 activity. Pretreatment of rats with unlabelled SDMH resulted in decreased labeling of DNA, RNA, proteins, and acid-soluble fractions after [3H]SDMH injection. A more pronounced effect was found after the daily treatment.
 
CBA female mice treated with 1,2-dimethylhydrazine developed a high incidence of benign and malignant tumours in the anal region. Many of these tumours originated from the perianal glands rather than the epidermis.
 
The aim of this work was to investigate if the possible chemopreventive effect of aspirin (ASA) on rat colon carcinogenesis could be detected with a medium-term assay. The end-point chosen was the inhibition of incidence and growth of putative preneoplastic lesions, the aberrant crypt foci (ACF) induced in the rat colon by two administrations of 1,2-dimethylhydrazine (DMH, 25 mg/kg p.o.). At both 4 and 8 weeks after the starting of the carcinogenic treatment the incidence of total ACF was reduced of 60% in rats receiving ASA (10 mg/kg/day p.o.) for 12 consecutive days during the initiation treatment with DMH. Also the number of the larger foci (with 3 or more crypts) was significantly lower in ASA-treated rats at both time-points (about 70% reduction). Moreover, concomitant ASA treatment determined a significant decrease of the mean number of crypts per focus at week 8. These results indicate that the chemopreventive effect of ASA on chemically-induced rat colon carcinogenesis observed in long-term studies may be detected in this relatively short assay.
 
The present study was designed to examine the effects of different high fat diets on the liver microsomal metabolism of aminopyrine (AMP) and 1,2-dimethylhydrazine (DMH). Male Sprague-Dawley rats were fed either a low fat (5% corn oil) or high fat (20%) diets containing either corn oil, menhaden oil or beef tallow for a period of up to 9 months. Liver microsomes were assayed for N-demethylase activity for both AMP and DMH substrates at 2 weeks, 1, 6 and 9 months of diet only, and also after 1, 2, 5 and 10 DMH treatments (20 mg/kg body weight). The menhaden oil-fed group had consistently higher AMP demethylase activity, which increased up to 6 months and then declined. Beef tallow-fed rats had the highest DMH demethylase activity following DMH, but this decreased by 10 treatments. These data indicate that type and amount of dietary fat affects microsomal metabolism of carcinogens, which may enhance tumor initiation.
 
Differences in the modifying effects of green tea catechins (GTC) on intestinal carcinogenesis by different formulations, doses and administration routes were investigated in male rats pretreated with 1,2-dimethylhydrazine (DMH). One hundred and eighty nine F344 male rats received subcutaneous injections of DMH at 40 mg/kg body weight twice a week for 3 weeks. Three days after completion of the carcinogen treatment, they were divided into nine groups. Each was administered a different source of 0.1% or 0.01% of GTC (Mitsui Norin Co. (M) or Taiyo Kagaku Co. (T)) either in the diet (D) or the drinking water (W), or basal diet and tap water alone without GTC for 33 weeks and then killed for autopsy. The survival rate tended to be lower with 0.01% MGTC (W) group than in the other groups. In the large intestine, although the multiplicity and/or incidences of adenomas showed tendencies for dose-dependent decrease in all GTC groups, and the average volumes of tumors tended to be decrease dose-dependently in the MGTC (W) and TGTC (W) groups, the multiplicity of carcinomas did not show such a trend, rather being significantly increased in the 0.01% MGTC (D) and 0.1% TGTC (W) groups. In the small intestine, the incidence and the multiplicity of tumors in all GTC treated groups had a tendency to decrease. On the other hand, the volume of tumors was increased with statistical significance in the 0.01% MGTC (W) and 0.1% TGTC (W) groups. Thus it can be concluded that GTC does not exert chemopreventive effects on intestinal carcinogenesis irrespective of its formulation, dose or route of administration.
 
The tumor-initiating activities of benzo[a]fluoranthene (BaF), benzo[b]fluoranthene (BbF), naphtho[1,2-b]fluoranthene (NbF) and naphtho[2,1-a]fluoranthene (NaF) were evaluated on the skin of female CD-1 mice. Each of these polycyclic aromatic hydrocarbons was assayed at total initiation doses of 1.0 and 4.0 mumol/mouse. These hydrocarbons were applied in 10 subdoses administered every other day. Promotion commenced 10 days after the last initiator dose and consisted of thrice weekly application of 2.5 micrograms of tetradecanoylphorbol acetate for 20 weeks. BbF was the most potent tumor initiator inducing a 100% incidence of tumor-bearing mice with an average of 8.5 tumors per mouse at a total initiator dose of 1.0 mumol. NaF was slightly more active as a tumor initiator than either NbF or BaF. NaF induced a 90% incidence of tumor-bearing mice with an average of 5.9 tumors per mouse at a total initiator dose of 1.0 mumol. BaF and NbF at a total initiator dose of 4.0 mumol exhibited similar tumor-initiating activity with both inducing a 90% incidence of tumor-bearing mice with an average of 4.3 and 6.6 tumors per mouse, respectively. However, at a total initiator dose of 1.0 mumol, BaF and NbF induced a 95% and 65% incidence of tumor-bearing mice with an average of 3.3 and 2.5 tumors per mouse, respectively.
 
The molecular geometries of two conformations (diequatorial and diaxial) of trans-1,2-dihydroxy-1,2-dihydro-8-fluoronaphthalene have been refined the ab initio gradient method at the 4-21G level to determine the effect of fluoro substitution on the conformational and structural properties of naphthalene dihydrodiols. As with trans-1,2-dihydroxy-1,2-dihydronaphthalene, the conformation with diequatorial hydroxyl groups is the most stable. The structural differences for the fluorinated and unfluorinated naphthalene dihydrodiols are discussed and the possible consequences of the structural and conformational trends on the metabolism of dihydrodiols to dihydrodiol epoxides are considered.
 
The degenerative behavior of cells following administration of 1,2-dimethylhydrazine was analyzed in its target organ, the distal colon of the mouse. Within 3-6 h after carcinogen treatment, an increasing number of epithelial cells in the proliferative compartment of the crypt degenerated. Degenerating cells were present most frequently as phagosomes in the neighboring epithelial cells, and infrequently as pyknotic nuclei being extruded from the epithelial lining in the crypt. Epithelial cells prelabeled with [3H]thymidine degenerated first, followed by those not prelabeled, indicating that the carcinogen-induced degeneration of cells occurred after passage of cells through the DNA synthesis phase.
 
Male Fischer rats were treated at 7 weeks of age with a single oral dose of 1,2-dimethylhydrazine (35 mg/kg). After 1.5 years, the 14 control and 28 treated animals were killed for general autopsy. The incidence of tumor formation in the treated animals was 78.6% as compared to 0% for the control animals. All tumors (1--3/rat) were located in the colon, with the exception of one in the Zymbal's gland of the ear and one in the small intestine. The dosage of 1,2-dimethylhydrazine used in this study is the lowest single oral dose of this carcinogen reported to induce colon tumors.
 
Nineteen preparations from 8 species of edible seaweeds, sodium alginate and cellulose powder were incorporated into a basic diet in proportions ranging from 0.05% to 2.0%, and used as experimental diets. Experimental rats were fed these diets and controls were fed the basic diet for 12 weeks. All rats also received the carcinogen, 1,2-dimethylhydrazine, during above period. After 20 weeks, all rats were autopsied and the incidence of intestinal tumors induced were examined. There was a significant decrease in incidence in rats fed 6 preparations from Eisenia bicyclis, Laminaria angustata, L. angustata var. longissima and Porphyra tenera (P less than 0.05).
 
Fermented milk products might be used for cancer chemoprevention due to their putative anticarcinogenic and antitumor activities. The diet was supplemented with freeze-dried milk fermented by Lactobacillus bulgaricus strain LBB.B 144 (product FFM.B 144) added throughout the experiment at doses of 1.3 g and 2.5 g per rat, 5 times a week starting 3 weeks before the first carcinogen injection. This treatment significantly inhibited, by 26.2-28.6% and by 34.2%, the total intestinal carcinogenesis induced by 1,2-dimethylhydrazine (DMH, 21 mg/kg, s.c., once per week for 20 weeks) in male and female BD6 rats, respectively. FFM.B144 decreased the tumor incidence and multiplicity in large bowel, caecum, and duodenum. Protective effects were better expressed in female animals, with exception of that observed in duodenum. Supplementation of diet with freeze-dried milk fermented by Lactobacillus bulgaricus strain LBB.B5 (product FFM.B5) inhibited DMH-induced carcinogenesis only in the large bowel, but had no significant protective effect when all intestinal tumors were taken into account. However, both freeze-dried products favorably shifted the differentiation of large bowel tumors by increasing the proportion of benign and highly differentiated malignant tumors and decreasing in parallel the number of poorly differentiated carcinomas without influencing the tumor size. A lower number of cases with visible mesenterial metastasis was also observed in FFM-treated rats. In addition, both FFM.B 144 and FFM.B5 significantly inhibited, by 26-33%, the induction in the same rats of ear-duct tumors. FFM.B144 but not FFM.B5 was also effective in inhibiting the tracheal carcinogenesis induced in Syrian golden hamsters by diethylnitrosamine (DEN, 100 mg/kg, two s.c. injections), the protective effect being better expressed in female animals. The anticarcinogenic potential of some fermented milk products might be exploited in chemoprevention of cancer in humans.
 
Sperm positive 12-14-day pregnant Holtzman rats were exposed to a single subcutaneous injection (20 mg/kg body wt) of 1,2-dimethylhydrazine (DMH). Two days post-exposure, the fetal intestinal tissues were examined for their content and metabolic activities for cyclic 3',5'-adenosine monophosphate (cAMP) and cyclic 3',5'-guanosine monophosphate (cGMP). The in utero exposure to the carcinogen resulted in lowering the intracellular content of cAMP and increasing cGMP. The decreased levels of cAMP may be accounted for the finding of a corresponding increase in its breakdown by its phosphodiesterases; however, associated with the increase in cGMP was correspondingly an increase in its phosphodiesterases, suggesting the activities for synthesis of this cyclic nucleotide may be the major factor for its elevated concentration. These observations indicate that DMH may cross the placental barrier and can effect the intracellular cyclic nucleotide concentrations in the fetal tissues as well as acting as a colorectal carcinogen in the adult rat. The changes in the cyclic nucleotide levels were toward the direction expected for an increased cell proliferation; consequently, further investigations are suggested to determine whether a hyperproliferative state is induced by the DMH in the already rapidly dividing fetal intestinal tissue.
 
Inhibitory effects of pyrazole on the carcinogenicities of 2 large-bowel carcinogens, 1,2-dimethylhydrazine (DMH) and azoxymethane (AOM), were examined, because our previous study revealed that pyrazole completely inhibited the induction of mutations by these carcinogens in the host-mediated mutation assay. ICR male mice were treated subcutaneously once a week for 20 weeks either with DMH or with AOM. Pyrazole was given orally to mice 2 h before treatment with the carcinogen. Pathological examinations were conducted 36 weeks after the first treatment. Treatment with DMH or AOM alone induced colorectal and/or anal tumorigenic lesions in 92% (23/25) mice of the DMH group and 100% (22/22) mice of the AOM group. By contrast, none of the animals in the combined treatment groups (carcinogen + pyrazole) developed those tumors. On the other hand, 50% (13/26) of mice treated with DMH alone and 78% (18/23) of mice treated with AOM alone developed vascular tumors. Pretreatment of mice with pyrazole reduced the percentage of mice bearing this type of tumor to about 30% of that in the carcinogen group with either carcinogen. These results clearly show that pyrazole has the ability to inhibit carcinogenicities of DMH and AOM, especially for the colorectum and anus, and indicate that the inhibition studies of mutation induction in vivo provide a useful tool for the screening for inhibitors of the carcinogenicities of DMH and AOM.
 
Eight-week-old mice of 3 sublines of strain C57BL/6 were given s.c. injections of 1,2-dimethylhydrazine (DMH), once weekly for 10 weeks. The highest incidence (85%) of colorectal tumors occurred in C57BL/6N mice. Colorectal tumors occurred in 43% of C57BL/6J mice, while only 3 (10%) C57BL/6Ha mice developed these tumors. Possible factors responsible for the differential susceptibility of 3 sublines of C57BL/6 mice to the induction of colorectal tumors by DMH are discussed.
 
Our earlier observation of increased incidence of 9,10-dimethyl-1,2-benzanthracene (DMBA) induced mammary carcinoma in young, virgin 'functionally' pinealectomized Holtzman rats poses the question whether or not a comparable incidence would occur in surgically pinealectomized rats reared in varying photoperiods (e.g. light/dark (LD) 24/0 or LD 10/14 schedules). Results show that functionally or surgically pinealectomized rats in LD 24/0 schedule have comparable mammary tumor incidence (95% and 83%, respectively) and latency period of tumor appearance (60 +/- 3.1 and 69.2 +/- 6.6 days, respectively). However, when surgically pinealectomized rats were kept in short photoperiods (LD 10/14), a significant difference was observed in both tumor incidence (60.9%) and latency period (91.8 +/- 11.0 days). Our data suggest that the susceptibility of the mammary gland to carcinogenic insult may be modulated by the concentration of the pineal hormone, melatonin, in the CNS.
 
1,2-Dimethylhydrazine dihydrochloride (DMH) is one of the most reliable carcinogens for experimental colonic carcinogenesis. In order to evaluate the biological significances of target organ specificity of DMH-induced carcinogenesis, specific pathogen free (SPF) BALB/c mice were injected subcutaneously with DMH for 30 weeks, and were studied pathologically for tumor development of various organs. The data showed that colon tumor developed only at 2% of these mice. However, it produced 100% incidence of malignant endotheliomas and angiosarcomas of blood vessels and these tumors selectively appeared in the liver. There were no overt foci of primary vascular tumors in the heart, lung, kidney, muscle as well as spleen. This tumor model may reveal that the organ specificity of the carcinogenic activity with DMH could be converted, possibly depending upon the bacterial flora in the intestines, and very suitable for the investigation of implications of intestinal bacteria on the colonic and vascular tumorigenesis.
 
Enhanced lipid peroxidation potential was measured in Holtzman rat colon tumors induced by chronic subcutaneous injection of 1,2-dimethyl-hydrazine as compared with normal colonic tissue. The peroxidation potentials were determined in the mitochondrial cellular components by measuring the ferrous-ascorbate induced formation of malondialdehyde. The tumor mitochondria were found to peroxidize at a rate 8-10-fold higher than the comparable normal tissue components. In addition, we found that the mitochondria from the cancer cells exhibited reduced NADH-cytochrome c reductase activity. These observations suggest an involvement of non-enzymatic free radical flux in DMH-induced carcinogenesis, which may be the result of structurally altered mitochondrial membranes.
 
Three hundred Kunming mice were randomly divided into six groups (half males and half females in each group). Group 1 was the positive control group, Groups 2, 3, 4 and 5 were experimental groups and Group 6 was used as the solvent control group. Mice in Groups 1-4 were injected with 1,2-dimethylhydrazine (1,2-DMH) (20 mg/kg body wt.) solution subcutaneously once a week from the 2nd week to the 20th week. From the 1st week to the 23rd week, mice in Groups 2, 3 and 4 were given catechin (1 mg/mouse), catechin (2 mg/mouse) and EGCG (2 mg/mouse), respectively, five times a week. Mice in Group 5 received only catechin (3 mg/mouse) five times a week from the 1st to the 23rd week. Mice in Group 6 were injected with an equal volume of 1 mmol EDTA solution subcutaneously once a week from the 2nd to the 20th week. At the end of the 27th week, all the mice were killed by cervical dislocation (Zhu, Q.H. and Zhu, Q.F. (1991) Laboratory Animal Science, 1st edition. The Junior Educational Publisher, Guangdong). Pathological examinations indicated that the incidence of large intestinal cancers occurring in Group 1 was 80%, significantly higher than that in Groups 2, 3 and 4 (p < 0.001). No tumors were found in Groups 5 and 6. This might suggest that green tea has preventive effects on large intestinal cancer induction in spite of the different doses of catechin. Immunohistochemistry studies showed that green tea catechins could enhance the activity of superoxide dismutase (SOD) in tissues.
 
Naphtho[1,2-b] furan-4,5-dione (NFD) was investigated for its anti-proliferation effect on human hepatocellular carcinoma (HCC), Hep3B, HepG(2), and Huh-7 cells. The effect of NFD on inhibiting proliferation and apoptosis was correlated with up-regulation of pro-apoptotic protein and down-regulation of pro-survival proteins. Remarkably, we found that NFD inhibited the nuclear translocation of NF-kappaB, likely accounting for the down-regulation of pro-survival Bcl-2 family. Furthermore, suppression of p38 MAPK activity by a specific inhibitor significantly rescued the cell proliferation inhibited by NFD. These findings suggest that signaling imbalance between p38 MAPK and NF-kappaB by NFD results in the proliferative inhibition and apoptosis of HCC tumor cells.
 
Top-cited authors
Hoyoku Nishino
  • Kyoto Prefectural University of Medicine
Ranjana Bird
  • University of Northern British Columbia
Mostafa A El-Sayed
  • Georgia Institute of Technology
Ivan H El-Sayed
  • University of California, San Francisco
Dennis Patrick O'Neal
  • Louisiana Tech University