[Show abstract][Hide abstract] ABSTRACT: In vivo models of human tumor vasculature are essential for the study of tumor angiogenesis and validation of therapeutic targets. To date, however, few standardized animal models of human tumor angiogenesis have been characterized. It was recently shown that human renal cell and prostate carcinoma primary xenografts, established from biopsy specimens, contained vessels lined mainly by human endothelial cells 1 month after implantation in immunodeficient mice. We selected colorectal cancer (CRC) as a primary xenograft model and studied the response of the vascular compartment to the new microenvironment during the same lapse of time. Immunohistochemical analysis of the origin of endothelial cells demonstrated that, in contrast to the mentioned study, human endothelial cells were rapidly substituted by their murine counterparts (nearly 50% by day 10 after implantation). Apoptotic human endothelial cells could not be detected 10 days after implantation, suggesting that apoptosis is not the mechanism underlying their replacement. Interestingly, host endothelial cells were found to colocalize with human laminin, suggesting a colonization of human vascular basement membranes after human endothelial cell disappearance. To rule out that the differences observed between the fate of human vasculature in the CRC model and those previously reported were because of methodological aspects, we established renal cell carcinoma (RCC) primary xenografts using the same protocol. In clear contrast with CRC xenografts, vasculature within RCC xenografts was mostly of human origin 35 days after implantation. These results support the notion of angiogenic heterogeneity in malignant neoplasms. Elucidation of the molecular mechanisms that determine persistence or disappearance of human endothelial cells in different tumor contexts can help to shed light on the intimate regulation of the angiogenic process.
[Show abstract][Hide abstract] ABSTRACT: Hereditary non-polyposis colorectal cancer (HNPCC) represents 1-3% of all colorectal cancers. HNPCC is caused by a constitutional defect in a mismatch repair (MMR) gene, most commonly affecting the genes MLH1, MSH2 and MSH6. The MMR defect results in an increased cancer risk, with the greatest lifetime risk for colorectal cancer and other cancers associated to HNPCC. The HNPCC-associated tumor phenotype is generally characterized by microsatellite instability (MSI) and immunohistochemical loss of expression of the affected MMR protein. The aim of this study was to determine the sensitivity of IHC for MLH1, MSH2 and MSH6, and MSI analysis in tumors from known MMR gene mutation carriers. Fifty-eight paired normal and tumor samples from HNPCC families enrolled in our high-risk colorectal cancer registry were studied for the presence of germline mutations in MLH1, MSH2 and MSH6 by DGGE and direct sequencing. MSI analysis and immunostaining for MLH1, MSH2 and MSH6 were evaluated. Of the 28 patients with a real pathogenic mutation, loss of immunohistochemical expression for at least 1 of these MMR proteins was found, and all except 1 have MSI-H. Sensitivity by MSI analysis was 96%. IHC analysis had a sensitivity of 100% in detecting MMR deficiency in carriers of a pathogenic MMR mutation, and can be used to predict which gene is expected to harbor the mutation for MLH1, MSH2 and MSH6. This study suggests that both analyses are useful for selecting high-risk patients because most MLH1, MSH2 and MSH6 gene carriers will be detected by this 2-step approach. This practical method should have immediate application in the clinical work of patients with inherited colorectal cancer syndromes.
[Show abstract][Hide abstract] ABSTRACT: Topoisomerase (Topo) II isoenzymes are the targets for drugs, such as epidophyllotoxins and doxorubicin. The aim of this study was to determine whether the expression of Topo IIalpha and Ki67 in advanced Hodgkin's disease (HD) played a role as a prognostic factor or predictor of response to treatment.
Forty-two patients who were homogeneously treated and had a long-term follow-up were selected for the study. Immunohistochemistry of paraffin-embedded tissue sections was performed. The effect of patient and tumor characteristics on failure-free survival (FFS) and overall survival were evaluated in a univariate analysis using the Cox proportional hazards model. The Cox model was also implemented in a multivariate analysis using stepwise selection.
Positive nuclear staining for Topo IIalpha in Reed-Stemberg or Reed-Stemberg variant cells was seen in 90% of HD cases, and coexpression of Ki67 and Topo IIalpha in 79%. No significant difference in the percentage of Topo IIalpha-positive cells was detected among histological HD subtypes. In the univariate analysis for FFS, the male gender, high lactate dehydrogenase, and Topo IIalpha < 30% were associated with more relapses. In the multivariate analysis for FFS, only Topo IIalpha < 30% was statistically associated with shorter FFS, with relative risk of 3 (95% confidence interval, 1.26-7.15; P = 0.013). In uni- and multivariate analyses for overall survival, only Topo IIalpha was associated with shorter survival.
Topo IIalpha expression could be useful in advanced HD to identify patients with a higher risk of relapse and lesser overall survival. It is of potential utility in the design of specific treatments.
Clinical Cancer Research 05/2003; 9(4):1406-11. · 7.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The development of new therapeutic strategies is essential for the management of gliomas, one of the most malignant forms of cancer. We have shown previously that the growth of the rat glioma C6 cell line is inhibited by psychoactive cannabinoids (I. Galve-Roperh et al., Nat. Med., 6: 313-319, 2000). These compounds act on the brain and some other organs through the widely expressed CB(1) receptor. By contrast, the other cannabinoid receptor subtype, the CB(2) receptor, shows a much more restricted distribution and is absent from normal brain. Here we show that local administration of the selective CB(2) agonist JWH-133 at 50 microg/day to Rag-2(-/-) mice induced a considerable regression of malignant tumors generated by inoculation of C6 glioma cells. The selective involvement of the CB(2) receptor in this action was evidenced by: (a) the prevention by the CB(2) antagonist SR144528 but not the CB(1) antagonist SR141716; (b) the down-regulation of the CB(2) receptor but not the CB(1) receptor in the tumors; and (c) the absence of typical CB(1)-mediated psychotropic side effects. Cannabinoid receptor expression was subsequently examined in biopsies from human astrocytomas. A full 70% (26 of 37) of the human astrocytomas analyzed expressed significant levels of cannabinoid receptors. Of interest, the extent of CB(2) receptor expression was directly related with tumor malignancy. In addition, the growth of grade IV human astrocytoma cells in Rag-2(-/-) mice was completely blocked by JWH-133 administration at 50 microg/day. Experiments carried out with C6 glioma cells in culture evidenced the internalization of the CB(2) but not the CB(1) receptor upon JWH-133 challenge and showed that selective activation of the CB(2) receptor signaled apoptosis via enhanced ceramide synthesis de novo. These results support a therapeutic approach for the treatment of malignant gliomas devoid of psychotropic side effects.
Cancer Research 09/2001; 61(15):5784-9. · 8.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The INK4a/ARF locus encodes two unrelated cell cycle-regulatory proteins that both function in tumor suppression, p16INK4a and p14ARF. In human tumors including breast cancer, alterations affecting selectively p14ARF have been poorly analysed. We have performed a comprehensive analysis of the inactivation mechanisms (mutation, homozygous and hemizygous deletion, and promoter hypermethylation) in a large series of 100 primary breast carcinomas. RT-PCR showed expression variable of the p14ARF transcript, with 17% demonstrating overexpression and 26% demonstrating decreased expression. No detectable alterations were observed in the majority of cases with overexpressed p14ARF mRNA, but 77% of tumors with decreased expression presented at least one of these genetic/epigenetic alterations. Nevertheless, a statistically significant correlation was observed between decreased p14ARF expression and several poor prognostic parameters.
[Show abstract][Hide abstract] ABSTRACT: To explore the induction of chemotherapy (CT) DNA damage and its correlation with tumor response and patient survival, we undertook the present study in 20 small cell lung cancer (SCLC) patients. All patients underwent the same treatment based on CT courses of carboplatin and etoposide. Blood samples were taken before and immediately after CT and every 12 weeks during follow-up. Nuclear DNA damage was determined through the variations in three mitochondrial pseudogene mutations in DNA of peripheral blood mononuclear cells. They were detected by mutation-specific PCR and assessed by a semiquantitative method. The relative level of mutation rose after chemotherapy in all cases. Among the 11 patients (55%) with higher relative levels of mutations, 9 (82%) of them achieved a complete response. In contrast, of the 9 patients (45%) with lower relative levels of mutations, only 2 (18%) achieved a complete response, displaying a statistically significant difference (P=0.02). The overall survival for patients with marked genomic damage was 18 months (range 10-24), and for patients with low degree of DNA damage, it was 12 months (range 5-15) (P=0.002). Genomic damage detected after chemotherapy treatment correlates positively with tumor response and patient survival.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 12/2000; 456(1-2):65-71. · 3.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hypermethylation of exon 1 of p16INK4a was examined in tumour and plasma DNA of a series of breast cancer patients. De novo methylation was observed in the tumours of eight patients (23%), and in plasma DNA in five (14%) of these eight patients. Our data show that de novo methylation of exon 1 of p16INK4a can be demonstrated in plasma DNA of breast cancer patients, a fact that provides additional evidence of the tumour-related origin of free plasma DNA in cancer patients.
British Journal of Cancer 07/1999; 80(8):1262-4. · 5.08 Impact Factor