Description

Cancer, the second leading cause of death, is a heterogenous group of over 100 diseases. Cancer is characterized by disordered and deregulated cellular and stromal proliferation accompanied by reduced cell death with the ability to survive under stresses of nutrient and growth factor deprivation, hypoxia, and loss of cell-to-cell contacts. At the molecular level, cancer is a genetic disease that develops due to the accumulation of mutations over time in somatic cells. The phenotype includes genomic instability and chromosomal aneuploidy that allows for acceleration of genetic change. Malignant transformation and tumor progression of any cell requires immortalization, loss of checkpoint control, deregulation of growth, and survival. A tremendous amount has been learned about the numerous cellular and molecular genetic changes and the host-tumor interactions that accompany tumor development and progression. It is the goal of the field of Molecular Oncology to use this knowledge to understand cancer pathogenesis and drug action, as well as to develop more effective diagnostic and therapeutic strategies for cancer. This includes preventative strategies as well as approaches to treat metastases. With the availability of the human genome sequence and genomic and proteomic approaches, a wealth of tools and resources are generating even more information. The challenge will be to make biological sense out of the information, to develop appropriate models and hypotheses and to translate information for the clinicians and the benefit of their patients. Cancer Biology & Therapy aims to publish original research on the molecular basis of cancer, including articles with translational relevance to diagnosis or therapy. We will include timely reviews covering the broad scope of the journal. The journal will also publish op-ed pieces and meeting reports of interest. The goal is to foster communication and rapid exchange of information through timely publication of important results using traditional as well as electronic formats. The journal and the outstanding Editorial Board will strive to maintain the highest standards for excellence in all activities to generate a valuable resource.

Publisher details

Landes Bioscience

Publications in this journal

• IGFBP2 as a brain tumor oncogene.

  Authors: Wei Zhang, Gregory Fuller

  Cancer biology & therapy. 6(7):995-6.

• Bexxar, iodine I 131 tositumomab, effective in long-term follow-up of non-Hodgkin's lymphoma.

  Authors: Mark Kaminski

  Cancer biology & therapy. 6(7):996-7.

• Therapeutic targeting of Brahma by HDAC inhibitors.

  Authors: David Reisman

  Cancer biology & therapy. 6(7):997-8.

• Heterogeneity of stromal fibroblasts in tumors.

  Authors: Akira Orimo, Robert A Weinberg

  Cancer biology & therapy. 6(4):618-9.

• Epidermal growth factor receptor plays a significant role in hepatocyte growth factor mediated biological responses in mammary epithelial cells.

  Authors: Alyssa R Bonine-Summers, Mary E Aakre, Kimberly A Brown, Carlos L Arteaga, Jennifer A Pietenpol, Harold L Moses, Nikki Cheng

  Cancer biology & therapy. 6(4):561-70.

  Breast cancers often have deregulated hepatocyte growth factor (HGF) and c-Met signaling that results in increased tumor growth and invasion. Elucidating the mechanism responsible for HGF/c-MetBreast cancers often have deregulated hepatocyte growth factor (HGF) and c-Met signaling that results in increased tumor growth and invasion. Elucidating the mechanism responsible for HGF/c-Met action in breast cancer progression has been difficult as c-Met communicates with a number of secondary receptors that can lead to various pathological outcomes. Understanding how these secondary receptors facilitate HGF/c-Met cellular responses will aid in the development of better therapeutic treatment options for breast cancer patients with elevated HGF signaling. In the present study it was shown that the epidermal growth factor receptor (EGFR) plays a significant role in HGF/c-Met mediated biological activities indicative of advanced tumor pathology, including enhanced proliferation and invasion. The clinically relevant EGFR inhibitor gefitinib was used to determine the role of EGFR in HGF-induced proliferation and motility in several mammary carcinoma cells including PyVmT, MDA-MB-231 and 4T1. Our analyses indicated that EGFR inhibition significantly blocked HGF activation of c-Met and EGFR and that inhibition of these pathways mitigated HGF induced proliferation and motility. The data indicate that this inhibition was not through a direct effect of gefitinib on c-Met, but that EGFR is necessary for c-Met activation in the assays performed. These results provide a novel mechanism of action for EGFR as a mediator of HGF signaling thereby linking EGFR to the oncogenic potential of c-Met in mammary carcinomas cells.

• Profiling of selenomethionine responsive genes in colon cancer by microarray analysis.

  Authors: Anne-Christine Goulet, George Watts, Jean L Lord, Mark A Nelson

  Cancer biology & therapy. 6(4):494-503.

  High-selenium containing yeast is being evaluated in clinical trials against colon polyp recurrence. However, the molecular targets for the anticancer effects of selenium remain unclear. PreviousHigh-selenium containing yeast is being evaluated in clinical trials against colon polyp recurrence. However, the molecular targets for the anticancer effects of selenium remain unclear. Previous studies by our group demonstrated that selenomethionine-induced growth arrest appears to be mediated by activation of ERK and subsequent phosphorylation of RSK and histone H3. These results suggest that selenomethionine can alter gene expression. In the present study, we have used cDNA microarrays to determine whether gene expression differences exist in HCT116 colon cancer cells treated with selenomethionine. These experiments reveal statistically significant expression changes for 50 genes. Genes we found to increase with selenomethionine treatment include KLK6, ATOX1, SGK, GJB2, DAP-1, PLAU, VIM, DPYSL2, STC2 and PXN. Conversely, genes downregulated by selenomethionine include PRKACB, LIM, DEPP, MYC, CDH5, ELF3, VSNL1, SAT and EGLN3. Further analysis of those genes using chromatin immunoprecipitation experiments showed that phosphorylated histone H3 on serine 10 bound to the GJB2 promoter (connexin 26) or the serum glucocorticoid kinase promoter is increased with selenomethionine treatment. Cells overexpressing CX26 or DAP-1 displayed a reduced number of colonies which suggests that these two genes could play a functional role in the growth inhibitory effects of selenomethionine. These data support the notion that selenomethionine-induced growth inhibition is associated with global changes in gene expression. They also demonstrate that selenomethionine can modify chromatin state to alter gene transcription. Finally, our studies provide a practical foundation for the further development of biomarkers to monitor the efficacy of selenomethionine in clinical trials.

• Using attenuated Salmonella typhi as tumor targeting vector for MDR1 siRNA delivery.

  Authors: Zhongming Jiang, Ping Zhao, Zhonghua Zhou, Jun Liu, Liying Qin, Hongwei Wang

  Cancer biology & therapy. 6(4):555-60.

  OBJECTIVE: To investigate the feasibility of using attenuated Salmonella typhi as an in vivo delivery vector for multidrug-resistance gene (MDR1) small interference RNA (siRNA) in a mouse modelOBJECTIVE: To investigate the feasibility of using attenuated Salmonella typhi as an in vivo delivery vector for multidrug-resistance gene (MDR1) small interference RNA (siRNA) in a mouse model bearing human tongue squamous cell cancer. This technique may represent a novel and effective route for the in vivo administration of siRNA against malignant tumors. METHODS: The cisplatin (DDP)-resistant human tongue squamous cell carcinoma cell line Tca8113/DDP, which highly expresses the MDR1 gene, was established by exposure to gradually increasing concentrations of cisplatin. A plasmid MDR1 siRNAwas constructed and transformed into attenuated Salmonella typhi strain SL7207. Tca8113/ DDP cells were infected with recombinant salmonella and expression of the MDR1 gene encoding P-glycoprotein (P-gp) product was detected. Tca8113/DDP tumor-bearing nude mice were established by inoculation by gavage administration of recombinant salmonella and were simultaneously injected intraperitoneally with cisplatin. Tumor growth was observed. RESULTS: Recombinant salmonella-bearing MDR1 siRNA expression plasmids can infect Tca8113/DDP cells in vitro and suppress P-gp expression and reverse DDP tolerance in Tca8113/DDP cells. Oral administration of recombinant salmonella in tumor-bearing nude mice can suppress tumor proliferation and enhance the therapeutic effect of DDP. CONCLUSION: Attenuated Salmonella typhi is expected to act as an in vivo targeting delivery vector for siRNA in tumor tissues.

• Evidence for the involvement of Puralpha in response to DNA replication stress.

  Authors: Huichen Wang, Meijuan Wang, Krzysztof Reiss, Nune Darbinian-Sarkissian, Edward M Johnson, George Iliakis, Shohreh Amini, Kamel Khalili, Jay Rappaport

  Cancer biology & therapy. 6(4):596-602.

  Puralpha is a sequence-specific nucleic acid binding protein that is involved in multiple cellular functions including regulation of transcription, initiation of DNA replication, cell cyclePuralpha is a sequence-specific nucleic acid binding protein that is involved in multiple cellular functions including regulation of transcription, initiation of DNA replication, cell cycle progression, and neuronal cell differentiation. Its potential role in DNA repair has not been explored. We have now analyzed the role of Puralpha in the cellular response to replication-associated DNA repair of double-strand breaks (DSBs) using Puralpha knockout mouse embryo fibroblasts (MEFs). We found that Puralpha negative cells are hypersensitive to the DNA replication inhibitor, hydroxyurea (HU), and that HU induces excessive DSBs, which delayed the resumption of cell cycle progression after HU treatment. Reintroduction of Pura into Pura null cells reduced the accumulation of DSBs and enhanced DNA end joining. These results suggest a role for Puralpha as a caretaker protein that is involved in the repair of DSBs induced by stalled replication forks.

• Silencing of heparanase by siRNA inhibits tumor metastasis and angiogenesis of human breast cancer in vitro and in vivo.

  Authors: Zhong-Hua Zhang, Yi Chen, Hua-Jun Zhao, Cheng-Ying Xie, Jian Ding, Yong-Tai Hou

  Cancer biology & therapy. 6(4):587-95.

  Expression of the heparanase gene is associated with invasive, angiogenic and metastatic potential of diverse malignant tumors and cell lines. Here we used RNA interference strategies to evaluate theExpression of the heparanase gene is associated with invasive, angiogenic and metastatic potential of diverse malignant tumors and cell lines. Here we used RNA interference strategies to evaluate the role of human heparanase in breast malignancy and to explore the therapeutic potential of its specific targeting. The siRNA targeting human heparanase almost completely inhibited the expression of heparanase in human breast carcinoma MDA-MB-435 cells, whereas the mismatched siRNA showed no effect. Cells transfected with heparanase siRNA expressed significantly less heparanase and profoundly reduced invasion and adhesion in vitro. In MDA-MB-435 cell xenograft model, tumors treated with siRNA were less vascularized and less metastatic than those treated with saline and the mismatched controls. The association of reduced levels of heparanase and altered tumorigenic properties in cells with anti-heparanase siRNA indicates that heparanase is important in cancer progress and has potential use as a target for anticancer drug development.

• EGFR inhibition in glioblastoma cells induces G2/M arrest and is independent of p53.

  Authors: Gurpreet S Kapoor, Antoire Christie, Donald M O'Rourke

  Cancer biology & therapy. 6(4):571-9.

  Mutations involving the TP53 gene are frequently identified in up to 50% of all human tumors, including glioblastomas. Analysis of expression patterns of TP53 in glioblastomas shows that it is mainlyMutations involving the TP53 gene are frequently identified in up to 50% of all human tumors, including glioblastomas. Analysis of expression patterns of TP53 in glioblastomas shows that it is mainly mutated in secondary glioblastomas and is less common in primary GBMs. However, the prognostic significance of TP53 loss of function in astrocytomas has always been controversial. In contrast, EGFR/erbB2 complexes have been implicated in the poor prognosis of several cancers, including glioblastomas. Our previous work showed that transforming phenotypes could be inhibited by interfering with active EGFR/erbB2 complex using mutant erbB2 proteins in wild-type p53 GBM cells. To assess the dependence of EGFR inhibited phenotype on p53, we used three mutant p53 glioblastoma cell lines in the present study and showed that mutant erbB2 can be exploited to inhibit EGFR-mediated oncogenic transformation irrespective of p53 status. Ectopic expression of a mutant erbB2 receptor (T691S) in mutant p53 GBM cells resulted in slower growth rate than empty vector controls. T691S-expressing clones exhibited a more flattened and nontransformed morphology. Consistently, T691S inhibited transformation in soft agar assays and tumor formation in nude mice independent of p53 status. Biochemical analysis showed reduced Akt and GSK-3 alpha/beta, but not p42/44MAPK phosphorylation, in T691S-expressing cells, when compared to parental controls, suggesting the P13-K pathway may be more relevant than MAPK for glial cell transformation. Cell cycle analysis showed reduced cyclin D1 and CDK6 and increased phospho-Cdc-2 (Tyr15) and p15INK4B in erbB2-inhibited cells, suggesting that nonfunctional EGFR/erbB2 complexes exert their inhibitory effects at various stages of the cell cycle to block the progression of cells through G2/M via Akt/GSK-3/Cdc2 pathway. Collectively, these observations provide a basis for receptor-based therapies that disable erbB receptors and inhibit proliferative signals in erbB-expressing human cancers including glioblastomas, regardless of their TP53 status.

• A phase II study of ixabepilone (BMS-247550) in metastatic renal-cell carcinoma.

  Authors: Edwin M Posadas, Samir Undevia, Elizabeth Manchen, James L Wade, A Dimitrios Colevas, Theodore Karrison, Everett E Vokes, Walter M Stadler

  Cancer biology & therapy. 6(4):490-3.

  INTRODUCTION: Ixabepilone (BMS-247550) is a semi-synthetic analog of epothilone B that has been characterized as a microtubule stabilizing agent with a mechanism of action distinct from taxanes.INTRODUCTION: Ixabepilone (BMS-247550) is a semi-synthetic analog of epothilone B that has been characterized as a microtubule stabilizing agent with a mechanism of action distinct from taxanes. Suggestion of activity in renal cell carcinoma (RCC) has been seen in early clinical studies. METHODS: Eligible patients had metastatic RCC as well as ECOG performance status 0-2 and normal organ function. Patients received ixabepilone at a dose of 40 mg/m2 intravenously over three hours every 21 days. There was no restriction on RCC histology or prior treatment type, but prior treatment with tubule inhibitors was not allowed. The primary endpoint was RECIST defined response and radiographic evaluations were performed every three cycles. Toxicity evaluations utilized CTCAE v3.0 and were performed every cycle. Using a Simon two-stage optimal design with alpha = 0.1, beta = 0.1, a null hypothesized response rate of 0.05 and an alternative response rate of 0.2, an initial 12 patients were to be accrued with full accrual of 37 patients if at least one response were observed. RESULTS: A median of five cycles were administered. No objective responses were observed in the first 12 evaluable patients, and six patients showed stable disease for more than 18 weeks on therapy. Median time to progression among those with objective progression was nine weeks. One patient experienced grade 4 anemia and lymphopenia. Grade 3 adverse events included lymphopenia, neutropenia, leukopenia, diarrhea, and infection. Common grade 2 toxicities included alopecia, fatigue and anemia. CONCLUSION: Ixabepilone administered at a dose of 40 mg/m2 every 21 days should not be advanced for further study in metastatic RCC. Given previous results, however, other dosing schedules may be worthy of further investigation.

• Velafermin improves gastrointestinal mucositis following irinotecan treatment in tumor-bearing DA rats.

  Authors: Rachel J Gibson, Andrea M Stringer, Joanne M Bowen, Richard M Logan, Ann S J Yeoh, Jaimi Burns, Enrique Alvarez, Dorothy M K Keefe

  Cancer biology & therapy. 6(4):541-7.

  Mucositis is a common, costly and unpleasant side effect of cancer chemotherapy and radiotherapy. Velafermin (FGF-20) has shown the potential to reduce these side effects. Irinotecan is aMucositis is a common, costly and unpleasant side effect of cancer chemotherapy and radiotherapy. Velafermin (FGF-20) has shown the potential to reduce these side effects. Irinotecan is a chemotherapeutic agent which is commonly used in solid tumors, and causes GI mucositis manifested by severe diarrhea. Therefore the primary aim of this study was to investigate whether velafermin reduces the GI mucositis induced by irinotecan. The secondary aim was to test varying schedules of administration of velafermin. Groups of tumor-bearing DA rats (6 per group) were treated with varying doses (4, 8 or 16 mg/kg) of velafermin intraperitoneally either prior to, prior to and during, or after chemotherapy treatment. Rats received a single dose of 200 mg/kg irinotecan intraperitoneally. Rats were monitored closely for the incidence and severity of diarrhea and mortality before being killed 192 h following treatment. Mortality, diarrhea and histopathology were assessed throughout the gastrointestinal tract. Severe or moderate diarrhea occurred in approximately 40% of rats treated with irinotecan alone. This was associated with a 50% mortality rate 96 h following chemotherapy. Velafermin administered at 16 mg/kg prior to irinotecan improved gastrointestinal mucositis as measured by reduced diarrhea and mortality following irinotecan chemotherapy in the DA rat. Rats that received velafermin prior to, or prior to and during irinotecan treatment did develop severe or moderate diarrhea, however it occurred later, in fewer rats and was not associated with mortality. Other dosing regimens were not as effective. This has important implications for the use of velafermin in GI mucositis in humans, and should be further studied.

• IGFBP-3 regulates esophageal tumor growth through IGF-dependent and independent mechanisms.

  Authors: Munenori Takaoka, Seok Hyun Kim, Takaomi Okawa, Carmen Z Michaylira, Douglas B Stairs, Cameron N Johnstone, Claudia D Andl, Ben Rhoades, James J Lee, Andres J P Klein-Szanto, Wafik S El-Deiry, Hiroshi Nakagawa

  Cancer biology & therapy. 6(4):534-40.

  Insulin-like growth factor binding protein (IGFBP)-3 exerts either proapoptotic or growth stimulatory effects depending upon the cellular context. IGFBP-3 is overexpressed frequently in esophagealInsulin-like growth factor binding protein (IGFBP)-3 exerts either proapoptotic or growth stimulatory effects depending upon the cellular context. IGFBP-3 is overexpressed frequently in esophageal cancer. Yet, the role of IGFBP-3 in esophageal tumor biology remains elusive. To delineate the functional consequences of IGFBP-3 overexpression, we stably transduced Ha-Ras(V12)-transformed human esophageal cells with either wild-type or mutant IGFBP-3, the latter incapable of binding Insulin-like growth factor (IGFs) as a result of substitution of amino-terminal Ile56, Leu80, and Leu81 residues with Glycine residues. Wild-type, but not mutant, IGFBP-3 prevented IGF-1 from activating the IGF-1 receptor and AKT, and suppressed anchorage-independent cell growth. When xenografted in nude mice, in vivo bioluminescence imaging demonstrated that wild-type, but not mutant IGFBP-3, abrogated tumor formation by the Ras-transformed cells with concurrent induction of apoptosis, implying a prosurvival effect of IGF in cancer cell adaptation to the microenvironment. Moreover, there was more aggressive tumor growth by mutant IGFBP-3 overexpressing cells than control cell tumors, without detectable caspase-3 cleavage in tumor tissues, indicating an IGF-independent growth stimulatory effect of mutant IGFBP-3. In aggregate, these data suggest that IGFBP-3 contributes to esophageal tumor development and progression through IGF-dependent and independent mechanisms.

• Finding the interface: more than an image.

  Authors: Yves Pommier

  Cancer biology & therapy. 6(4):620-3.

• MUC1: a target molecule for cancer therapy.

  Authors: Ravibhushan Singh, Dilip Bandyopadhyay

  Cancer biology & therapy. 6(4):481-6.

  MUC1 is a mucin family protein, overexpressed in more than 90% of breast cancers in an underglycosylated form, exposing the core peptides of the extracellular domain that act as a potential targetMUC1 is a mucin family protein, overexpressed in more than 90% of breast cancers in an underglycosylated form, exposing the core peptides of the extracellular domain that act as a potential target for antibody-mediated therapy. The highly conserved repeats of 20 amino acids VNTR varies between 20 and 125 depending on the allele. Each tandem repeat contains five potential O-glycosylation sites that have been exploited in designing cancer therapeutics. The core peptides in the tandem repeated VNTR domain are masked in normal cells and become exposed in the cancer cells associated mucins. The characteristics of the MUCI epitopes constituted with the tandem repeats and the carbohydrates present on MUC1 induce immune responses that favor targeted immunotherapy. In addition, aberrant glycosylation also plays an important role in enhancing the internalization of MUC1 into the cytoplasm making MUC1 a very attractive cytoplasmic delivery system of drugs and other therapeutic agents. MUC1 being present on most of the cancers of glandular epithelial origin, appears as a potential target for therapeutic interventions in these cancers.

• Proteasome inhibition specifically sensitizes leukemic cells to anthracyclin-induced apoptosis through the accumulation of Bim and Bax pro-apoptotic proteins.

  Authors: Arnaud Pigneux, François-Xavier Mahon, François Moreau-Gaudry, Maialene Uhalde, Hubert de Verneuil, Francis Lacombe, Josy Reiffers, Noel Milpied, Vincent Praloran, Francis Belloc

  Cancer biology & therapy. 6(4):603-11.

  Proteasome inhibitors are a novel class of compounds that might increase sensitivity to chemotherapy for acute myeloid leukemia (AML). We quantified apoptosis in THP-1 cells incubated with idarubicinProteasome inhibitors are a novel class of compounds that might increase sensitivity to chemotherapy for acute myeloid leukemia (AML). We quantified apoptosis in THP-1 cells incubated with idarubicin (IDA) alone or together with a low concentration of MG132 or bortezomib. The combination of both drugs yielded a percentage of apoptotic cells that was significantly higher than the additive effect of both drugs administered separately (p < 0.01). Isobologram analysis showed that both MG132 and bortezomib interacted synergistically with IDA to induce apoptosis of THP1 cells. Western blot analysis of Bax and Bim show an acumulation of these pro-apoptotic proteins in THP1 treated cells. This increase in Bim preceded the induction of apoptosis and participated in idarubicin-induced apoptosis. Proteasome inhibition also potentiated IDA-induced apoptosis in primary blast cells from 22 AML patients while no such effect was found on normal lymphocytes, PHA-stimulated lymphocytes, normal cord blood CD34+ cells or bone marrow normal myeloid cells. These data show that MG132 and bortezomib specifically sensitize leukemic cells to IDA through an increase in BIM and Bax pro-apoptotic Bcl-2 family proteins.

• Therapeutic effect of arsenic trioxide (As2O3) on cervical cancer in vitro and in vivo through apoptosis induction.

  Authors: Jing Yu, Haili Qian, Yunfeng Li, Yang Wang, Xueyan Zhang, Xiao Liang, Ming Fu, Chen Lin

  Cancer biology & therapy. 6(4):580-6.

  Arsenic trioxide (As2O3) induces apoptosis in certain types of cancer cells. But the detailed mechanisms of As2O3 efficacy are not completely known. Here we demonstrate that As2O3 has a therapeuticArsenic trioxide (As2O3) induces apoptosis in certain types of cancer cells. But the detailed mechanisms of As2O3 efficacy are not completely known. Here we demonstrate that As2O3 has a therapeutic effect on cervical cancer in vitro and in vivo. We investigated the As2O3-induced apoptosis in various cervical cancer cells. The apoptosis was triggered by mitochondrial pathway and associated with dissociation of Bcl-2 from Bax and VDAC, then the release of cytochrome c from Bax and VDAC channel, resulting in the activation of caspase-9 and caspase-3. The overexpression of Bcl-2 counteracted the As2O3-mediated apoptosis. The As2O3 treatment also resulted in an increased M phase cell cycle distribution by inducing microtubule polymerization. Two independent death-signaling pathways in cervical cancer cells were activated, one dominated by JNK/p38/GADD45 and one by p53 signals. Further investigation involving assessment of As2O3 on tumor cell growth in mice indicated that As203 also inhibited in vivo tumor growth. As2O3 as an inhibitor of cervical cancer proliferation both in vitro and in vivo suggests a potential clinical application in cervical cancer therapies.

• High copy amplification of the Aurora-A gene is associated with chromosomal instability phenotype in human colorectal cancers.

  Authors: Naoshi Nishida, Takeshi Nagasaka, Kazuhiro Kashiwagi, C Richard Boland, Ajay Goel

  Cancer biology & therapy. 6(4):525-33.

  Chromosomal instability (CIN) is a common but not universal feature of colorectal cancer (CRC); however, the molecular basis for CIN is controversial and poorly understood. There are many plausibleChromosomal instability (CIN) is a common but not universal feature of colorectal cancer (CRC); however, the molecular basis for CIN is controversial and poorly understood. There are many plausible mechanisms proposed for CIN, including disruption of G1/S and G2/M checkpoint regulation, and alterations in the spindle checkpoint genes. However, mutations in individual growth regulatory genes are not commonly observed in CRC. Therefore, a more comprehensive analysis of the genes involved in each cell cycle checkpoint regulatory pathway might be required to evaluate a possible role for involvement in CIN. We investigated the presence of high copy amplification of the cyclin E, Aurora-A, Skp2 genes, mutation of ubiquitin ligase CDC4, and promoter methylation of Mad2L1, as well as the expression of the gene products in a panel of 11 human CRC cell lines as well as 48 human CRC specimens. In the cell lines with CIN, we found amplification of the Aurora-A, cyclin E and Skp2 genes, and a mutation in the CDC4 gene, all of which resulted in altered expression of the cognate proteins. In the human CRC tissues, amplification of Aurora-A was frequent (29%), while alterations were rarely observed in cyclin E, Skp2 or CDC4. Aurora-A amplification was strongly associated with a high fractional allelic loss score (p = 0.0001), but not with microsatellite instability, nor with the promoter methylation phenotype in these tumors. Our data confirm involvement in the CDC4-cyclin E pathway of the development of the CIN phenotype in human CRC, and find that amplification of the Aurora-A is a common target for disruption of this pathway.

• Pheophorbide a, an active component in Scutellaria barbata, reverses P-glycoprotein-mediated multidrug resistance on a human hepatoma cell line R-HepG2.

  Authors: Patrick Ming-Kuen Tang, Judy Yuet-Wa Chan, Dong-Mei Zhang, Shannon Wing-Ngor Au, Wing-Ping Fong, Siu-Kai Kong, Stephen Kwok-Wing Tsui, Mary Mui-Yee Waye, Thomas Chung-Wai Mak, Kwok-Pui Fung

  Cancer biology & therapy. 6(4):504-9.

  Scutellaria barbata, a Traditional Chinese Medicine native in southern China, has been widely used for treating liver diseases. In this study, the anti-proliferative effect of Pheophorbide a (Pa), anScutellaria barbata, a Traditional Chinese Medicine native in southern China, has been widely used for treating liver diseases. In this study, the anti-proliferative effect of Pheophorbide a (Pa), an active component from S. barbata, was examined on a multi-drug resistant (MDR) human hepatoma cell line R-HepG2. Our study showed that Pa could significantly inhibit the growth of R-HepG2 cells with an IC50 value at 25.0 microM after 48 hours treatment. When compared with the parental HepG2 cells, Pa showed weak resistance to R-HepG2. Efflux of Pa out of R-HepG2 cells was not observed as its cellular uptake level showed no significant difference comparing with HepG2 cells. Interestingly, significant reduction of P-glycoprotein expression on Pa-treated R-HepG2 cells was found at both transcriptional and translational levels, leading to reduction of P-glycoprotein activity. In addition, mechanistic study elucidated that Pa induced cell cycle arrest at G2/M phase and inhibited the expressions of G2/M phase cell cycle regulatory proteins, cyclin-A1 and cdc2 in a dose-dependent manner.

• ErbB3 expression and dimerization with EGFR influence pancreatic cancer cell sensitivity to erlotinib.

  Authors: Andrey Frolov, Kyle Schuller, Ching-Wei D Tzeng, Emily E Cannon, Brandon C Ku, J Harrison Howard, Selwyn M Vickers, Martin J Heslin, Donald J Buchsbaum, J Pablo Arnoletti

  Cancer biology & therapy. 6(4):548-54.

  Abnormal expression and signaling of ErbB receptors has been implicated in multiple epithelial malignancies, including pancreatic cancer. Erlotinib, an epidermal growth factor receptor tyrosineAbnormal expression and signaling of ErbB receptors has been implicated in multiple epithelial malignancies, including pancreatic cancer. Erlotinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), has been recently approved for pancreatic cancer treatment, but there are no reliable predictors of patient response. Expression of additional ErbB receptors seems to influence tumor response to EGFR-targeted therapy. We analyzed the influence of ErbB3 expression on pancreatic cancer cell response to erlotinib treatment. Proliferation assays of five human pancreatic cancer cell lines were performed following treatment with erlotinib. Expression and phosphorylation profiles of ErbB receptors and downstream adaptor protein (Akt, ERK1/2, STAT3, mTOR) were evaluated following stimulation with EGF or neuregulin-beta. The formation of EGFR homodimers and EGFR-ErbB3 heterodimers, necessary to enable ErbB3 downstream signaling, was demonstrated by chemical cross-linking assays. The effects of RNA inhibition of ErbB3 on sensitivity to erlotinib treatment were evaluated in AsPC-1 pancreatic cancer cells. Erlotinib inhibited Akt phosphorylation and proliferation of all the ErbB3-expressing cell lines but did not affect mTOR activation. Cross-linking studies confirmed the presence of EGFR-ErbB3 heterodimers in pancreatic cancer cells. Only the ErbB3-deficient MIA PaCa-2 cells displayed persistent Akt activation and ongoing proliferation in spite of erlotinib treatment. siRNA-mediated inhibition of ErbB3 expression in AsPC-1 cells resulted in acquired resistance to erlotinib treatment. Pancreatic cancer cells which lack ErbB3 do not display activation of the ErbB3-PI3K-Akt cascade induced by EGFR/ErbB3 heterodimers and become less critically dependent on EGFR signaling and therefore resistant to erlotinib. Pancreatic cancer expression of ErbB3 may be useful for EGFR-targeted therapy patient selection.

• Hsp60 and Hspl0 as antitumor molecular agents.

  Authors: Francesco Cappello, Anna M Czarnecka, Giampiero La Rocca, Antonino Di Stefano, Giovanni Zummo, Alberto J L Macario

  Cancer biology & therapy. 6(4):487-9.

  The molecular chaperones Hsp60 and Hsp10 are, according to recent reports, involved in cancer development and progression. We, for instance, have found that their expression varies with distinctiveThe molecular chaperones Hsp60 and Hsp10 are, according to recent reports, involved in cancer development and progression. We, for instance, have found that their expression varies with distinctive patterns in different malignancies: they are overexpressed in colorectal, exocervical and prostate carcinogenesis, and colorectal cancer progression, but they are downregulated during bronchial carcinogenesis. There is also evidence showing that Hsp60 and Hsp10 can be used as therapeutic agents, for example in rheumatoid arthritis. In view of these findings we want now to call attention to the potential of Hsp60 and Hsp10 in cancer therapy.

• Shift in AP-2alpha localization characterizes astrocytoma progression.

  Authors: Ramona Britto, S Umesh, A S Hegde, Sridevi Hegde, Vani Santosh, B A Chandramouli, Kumaravel Somasundaram

  Cancer biology & therapy. 6(3):413-8.

  Activator protein 2alpha (AP-2alpha) has been shown to be lost in the advanced stages of many cancers, including gliomas. In this study, we wanted to analyze the expression of AP-2alpha inActivator protein 2alpha (AP-2alpha) has been shown to be lost in the advanced stages of many cancers, including gliomas. In this study, we wanted to analyze the expression of AP-2alpha in astrocytoma samples of different grades both at the RNA level, by real-time qPCR and at the protein level, by immunohistochemistry, and to examine its correlation, if any, with patient outcome. Five Grade I, 14 Grade II, 18 Grade III, 72 Grade IV samples and 13 normal brain controls were included. We did not find any clear pattern of regulation at the RNA level with tumor grade. The RNA expression levels however, correlated to a large extent with the nuclear AP-2alpha staining in these samples (72.09%; 31/43). Further, we did not find a complete loss of nuclear AP-2alpha expression in the higher grades, in contrast to previous reports. Interestingly, we found cytoplasmic AP-2alpha expression in a majority of higher grade astrocytomas (Grade IV-85%; 33/39 and Grade III-74%; 14/19) in comparison to lower grades (Grade I-0%; 0/5 and Grade II-37.5%; 3/8) suggesting that the translocation of this protein from the nucleus to the cytoplasm may be responsible for the increased malignancy. The nuclear expression in these grades was found to be concomitantly reduced. Within GBMs, we found that decreased nuclear expression was indicative of a better prognosis. The striking observation was the shift in localization of this protein from the nucleus to the cytoplasm with increasing tumor grade, pointing to a crucial role for this transcription factor in the progression of astrocytomas.

• Adenovirus-mediated PEDF expression inhibits prostate cancer cell growth and results in augmented expression of PAI-2.

  Authors: Ming Guan, Haowen Jiang, Chong Xu, Rong Xu, Zhongqing Chen, Yuan Lu

  Cancer biology & therapy. 6(3):419-25.

  PEDF is one of the most potent inhibitor of angiogenesis. Loss of PEDF was found in human prostate tumors and associated with the progression toward a metastatic phenotype. To test the therapeuticPEDF is one of the most potent inhibitor of angiogenesis. Loss of PEDF was found in human prostate tumors and associated with the progression toward a metastatic phenotype. To test the therapeutic potential of PEDF, we constructed a replication-defective adenoviral vector capable of efficient transduction and expression of PEDF (Ad-PEDF) in PC-3 prostate carcinoma cells. As controls, we used adenoviruses expressing beta-galactosidase (Ad-LacZ). We showed that overexpression of PEDF inhibited proliferation of cells and augmented apoptosis in serum-starved cells, in comparison with Ad-LacZ. Furthermore, Ad-PEDF suppresses anchorage-independent growth cells in soft agar and tumor formation in athymic nude mice associated with decreased microvessel density. Microarray analysis showed that 56 out of 8464 genes were found to be upregulated and downregulated in the PC-3 infected with Ad-PEDF as compared with Ad-LacZ. The differentially expressed genes cover a broad range of functional activities including catalytic activity, protein binding, signal transduction activity and cell invasion. Among them, PAI-2 and DRHC were confirmed to be upregulated with real-time PCR and Western blot, suggesting a possible association with PEDF-induced signaling for cell motility and metastasis. These results can contribute to our understanding of the molecular mechanisms of treatment strategies of PEDF for prostate cancer.

• Differentiation of vascular and non-vascular skin spectral signatures using in vivo hyperspectral radiometric imaging: implications for monitoring angiogenesis.

  Authors: Paul C Tumeh, Jeremy M Lerner, David T Dicker, Wafik S El-Deiry

  Cancer biology & therapy. 6(3):447-53.

  Molecular imaging techniques can detect and monitor characteristics of the tumor microenvironment, such as angiogenesis, hypoxia, metabolism, and apoptosis that may better correlate with response toMolecular imaging techniques can detect and monitor characteristics of the tumor microenvironment, such as angiogenesis, hypoxia, metabolism, and apoptosis that may better correlate with response to cancer therapy and may provide information in real-time. We investigated the use of a novel, spatially discrete, hyperspectral, multi-fiber optical system to characterize selected regions of skin in living mice. We determined the reproducibility and robustness of the spectral signatures derived from comparable regions of interest. Additionally, we characterized spectral differences in vascular and non-vascular fields to determine their potential use in monitoring angiogenesis. The macroscopic Prism and Reflectance Imaging Spectroscopy System (MACRO-PARISS) was calibrated against a National Institute for Standards and Technology (NIST)-certified lamp, allowing for reproducible spectra with any instrument similarly calibrated. Spectra were classified using a linearity-independent algorithm over a wavelength range of 450-920 nm. Classified spectra were integrated into a spectral library and subsequent acquisitions were correlated with the library set to a minimum correlation coefficient (MCC) of 99%. The results indicated that similar regions of interest with respect to vascularity consistently generated a unique spectral signature. As the field of view (FOV) moved from vascular to non-vascular areas, the acquired spectra changed in a step-wise and predictable fashion. Additionally, vascular fields that were deprived of their blood supply subsequently generated a non-vascular spectral signature. This work has implications for the monitoring of various physiologic or pathological processes including tumor angiogenesis and the therapeutic effects of anti-vascular agents.

• ABT-510, a modified type 1 repeat peptide of thrombospondin, inhibits malignant glioma growth in vivo by inhibiting angiogenesis.

  Authors: Joshua C Anderson, J Robert Grammer, Wenquan Wang, L Burton Nabors, Jack Henkin, Jerry E Stewart, Candece L Gladson

  Cancer biology & therapy. 6(3):454-62.

  Anti-angiogenic therapies would be particularly beneficial in the treatment of malignant gliomas. Peptides derived from the second type 1 repeat (TSR) of thrombospondin-1 (TSP-1) have been shown toAnti-angiogenic therapies would be particularly beneficial in the treatment of malignant gliomas. Peptides derived from the second type 1 repeat (TSR) of thrombospondin-1 (TSP-1) have been shown to inhibit angiogenesis in non-glioma tumor models and a modified TSR peptide, ABT-510, has now entered into Phase II clinical trials of its efficacy in non-glioma tumors. As microvascular endothelial cells (MvEC) exhibit heterogeneity, we evaluated the ability of the modified TSR peptide (NAcSarGlyValDallolleThrNvalleArgProNHE, ABT-510) to inhibit malignant glioma growth in vivo and to induce apoptosis of brain microvessel endothelial cells (MvEC) propagated in vitro. We found that daily administration of ABT-510 until euthanasia (days 7 to 19), significantly inhibited the growth of human malignant astrocytoma tumors established in the brain of athymic nude mice. The microvessel density was significantly lower and the number of apoptotic MvEC was significantly higher (3-fold) in the tumors of the ABT-510-treated animals. Similar results were found using a model in which the established tumor is an intracerebral malignant glioma propagated in a syngeneic mouse model. ABT-510 treatment of primary human brain MvEC propagated as a monolayer resulted in induction of apoptosis in a dose- and time-dependent manner through a caspase-8-dependent mechanism. It also inhibited tubular morphogenesis of MvEC propagated in collagen gels in a dose- and caspase-8 dependent manner through a mechanism that requires the TSP-1 receptor (CD36) on the MvEC. These findings indicate that ABT-510 should be evaluated as a therapeutic option for patients with malignant glioma.

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