Intratumor injection of the Hsp90 inhibitor 17AAG decreases tumor growth and induces apoptosis in a prostate cancer xenograft model.

PURPOSE: A role for heat shock protein 90 inhibitors in prostate cancer has been explored only in the context of systemic treatment of refractory metastatic disease. We hypothesized that intratumor administration of heat shock protein 90 inhibitors may have benefit for treating localized prostate cancer. MATERIALS AND METHODS: Twice weekly intratumor injections of 50 mg/kg 17AAG (treatment group of 8 mice) or dimethyl sulfoxide (control group of 8) were performed in subcutaneously grown DU-145 prostate cancer xenografts for a total of 8 doses. Tumor size was monitored. An additional tumor nonintervention control group of 3 mice was maintained. RESULTS: Seven of the 8 mice (88%) in the 17AAG group lived to study completion, of which 6 (86%) showed decreased tumor size and growth rate compared to those of vehicle treated controls (p <0.05). Gross necropsy, and tumor histological and molecular evaluations were performed after sacrifice. No overt signs of systemic toxicity, evidence of distant metastases or peritumor tissue effects were noted. Histologically 17AAG treated tumors were characterized by marked necrosis, inflammation and complete destruction of cellular architecture. Intratumor 17AAG treatment also resulted in pharmacodynamic changes consistent with apoptosis. CONCLUSIONS: The current data demonstrate that intratumor administration of 17AAG promotes tumor growth inhibition, pertinent client protein responses and localized induction of apoptosis together with minimal clinical toxicity. These data support further preclinical evaluation of this treatment modality alone and in combination with other established noninvasive therapy for localized prostate cancer.

The in vitro and in vivo effects of re-expressing methylated von Hippel-Lindau tumor suppressor gene in clear cell renal carcinoma with 5-aza-2'-deoxycytidine.

PURPOSE: Clear cell renal carcinoma (ccRCC) is strongly associated with loss of the von Hippel-Lindau (VHL) tumor suppressor gene. The VHL gene is functionally lost through hypermethylation in up to 19% of sporadic ccRCC cases. We theorized that re-expressing VHL silenced by methylation in ccRCC cells, using a hypo-methylating agent, may be an approach to treatment in patients with this type of cancer. We test the ability of two hypo-methylating agents to re-express VHL in cell culture and in mice bearing human ccRCC and evaluate the effects of re-expressed VHL in these models. EXPERIMENTAL DESIGN: Real-time reverse transcription-PCR was used to evaluate the ability of zebularine and 5-aza-2'-deoxycytidine (5-aza-dCyd) to re-express VHL in four ccRCC cell lines with documented VHL gene silencing through hypermethylation. We evaluated if the VHL re-expressed after hypo-methylating agent treatment could recreate similar phenotypic changes in ccRCC cells observed when the VHL gene is re-expressed via transfection in cell culture and in a xenograft mouse model. Finally we evaluate global gene expression changes occurring in our cells, using microarray analysis. RESULTS: 5-Aza-dCyd was able to re-express VHL in our cell lines both in culture and in xenografted murine tumors. Well described phenotypic changes of VHL expression including decreased invasiveness into Matrigel, and decreased vascular endothelial growth factor and glucose transporter-1 expression were observed in the treated lines. VHL methylated ccRCC xenografted tumors were significantly reduced in size in mice treated with 5-aza-dCyd. Mice bearing nonmethylated but VHL-mutated tumors showed no tumor shrinkage with 5-aza-dCyd treatment. CONCLUSION: Hypo-methylating agents may be useful in the treatment of patients having ccRCC tumors consisting of cells with methylated VHL.

Predicting survival in patients with metastatic kidney cancer by gene-expression profiling in the primary tumor.

To identify potential molecular determinants of tumor biology and possible clinical outcomes, global gene-expression patterns were analyzed in the primary tumors of patients with metastatic renal cell cancer by using cDNA microarrays. We used grossly dissected tumor masses that included tumor, blood vessels, connective tissue, and infiltrating immune cells to obtain a gene-expression "profile" from each primary tumor. Two patterns of gene expression were found within this uniformly staged patient population, which correlated with a significant difference in overall survival between the two patient groups. Subsets of genes most significantly associated with survival were defined, and vascular cell adhesion molecule-1 (VCAM-1) was the gene most predictive for survival. Therefore, despite the complex biological nature of metastatic cancer, basic clinical behavior as defined by survival may be determined by the gene-expression patterns expressed within the compilation of primary gross tumor cells. We conclude that survival in patients with metastatic renal cell cancer can be correlated with the expression of various genes based solely on the expression profile in the primary kidney tumor.