Cytotoxic chemotherapy for metastatic renal cell carcinoma

Overexpression of COPS3 promotes clear cell renal cell carcinoma progression via regulation of Phospho-AKT(Thr308), Cyclin D1 and Caspase-3

The third subunit of the COP9 signalosome (COPS3) is associated with cell proliferation and tumorigenesis process in cancer. The present study showed that the expression level of COPS3 was upregulated in malignant cell lines and COPS3 overexpression was related with clinical stage, T stage, historical grade. Kaplan-Meier survival curves showed that COPS3 may function as a prognostic factor for overall survival. CCK-8 and colony formation assays revealed that knockdown of COPS3 in ACHN and 786-O significantly impacted proliferation in vitro. In addition, flow cytometry showed that inhibition of COPS3 induced G0/G1 arrest and promoted apoptosis. COPS3 may promote kidney cancer progression by altering Phospho-AKT(Thr308), Cyclin D1 and Caspase-3 expression. Collectively, Our findings suggest that COPS3 may be a new potential target of ccRCC.

VHL deficiency augments anthracycline sensitivity of clear cell renal cell carcinomas by down-regulating ALDH2

The von Hippel-Lindau (VHL) is deficient in ∼70% of clear-cell renal cell carcinomas (ccRCC), which contributes to the carcinogenesis and drug resistance of ccRCC. Here we show that VHL-deficient ccRCC cells present enhanced cytotoxicity of anthracyclines in a hypoxia-inducible factor-independent manner. By subtractive proteomic analysis coupling with RNAi or overexpression verification, aldehyde dehydrogenase 2 (ALDH2) is found to be transcriptionally regulated by VHL and contributes to enhanced anthracyclines cytotoxicity in ccRCC cells. Furthermore, VHL regulates ALDH2 expression by directly binding the promoter of −130 bp to −160 bp to activate the transcription of hepatocyte nuclear factor 4 alpha (HNF-4α). In addition, a positive correlation is found among the protein expressions of VHL, HNF-4α and ALDH2 in ccRCC samples. These findings will deepen our understanding of VHL function and shed light on precise treatment for ccRCC patients.

The VHL tumour suppressor gene is lost in approximately 70% of clear cell renal cell carcinoma (ccRCC). In this study, the authors demonstrate that VHL loss in these tumours augments anthracyclines chemotherapy by down-regulation of ALDH2.

A phase II trial of gemcitabine, capecitabine, and bevacizumab in metastatic renal carcinoma

OBJECTIVES

Renal cancer is resistant to most DNA and DNA repair targeted chemotherapy; although moderate response rates to nucleotide analog based therapy have been reported. Bevacizumab also has activity. We thus performed a phase II trial of gemcitabine, capecitabine, and bevacizumab in patients with metastatic renal cancer.

METHODS

Following significant hematotoxicity, dosing was modified to gemcitabine 1000 mg/m (Days 1, 8), capecitabine 1000 mg twice daily (Days 1-14), and bevacizumab 15 mg/kg (Day 1) on a 21-day cycle with evaluation every 3 cycles. Primary end point was objective response rate.

RESULTS

Twenty-nine patients were enrolled between March 2005 and May 2008. Most patients had been previously treated with a vascular endothelial growth factor receptor tyrosine kinase inhibitor. Seven patients (24%) had a partial response. Median overall and progression-free survival were 9.8 months (95% confidence interval: 6.2, 14.9) and 5.3 months (95% confidence interval: 3.9, 9.9), respectively. The regimen was well tolerated with hematologic toxicity, fatigue, and rash being most common.

CONCLUSION

The trial was terminated early despite not meeting criteria for success or futility because of slow accrual and because the historical response rate became irrelevant with emerging data using sequential vascular endothelial growth factor therapies. Nevertheless, the observed progression-free and overall survival compare favorably to other phase II trials in this heavily pretreated population.

Vascular endothelial growth factor pathway-targeted therapy as initial systemic treatment of patients with renal cancer

Advanced renal cancer is known to be largely refractory to traditional DNA- and DNA repair-targeted chemotherapy. Until recently, immunotherapy had been the mainstay for the treatment; however, it is effective in only a small proportion of patients. Advances in the understanding of the association between the von Hippel-Lindau pathway and angiogenesis and their role in the development of renal cancer has led to the development of highly effective vascular endothelial growth factor (VEGF) pathway-targeted inhibitors. Several such novel agents have demonstrated increased clinical benefit, progression-free survival, and superior quality of life in large, randomized phase III clinical trials, and additional VEGF pathway inhibitors are currently being studied. This review will summarize the major clinical trials and practical recommendations for the most studied VEGF inhibitors, including sunitinib, sorafenib, and bevacizumab; introduce novel VEGF inhibitor agents; outline side effects and toxicities; and discuss sequential and combination therapy with these agents.

Cryoablation of renal cancer: variables involved in freezing-induced cell death

The detection of renal tumors has increased significantly over recent years resulting in a greater demand for novel, minimally invasive techniques. Cryoablation has emerged as a valuable treatment modality for the management of renal cancer. In an effort to detail the effects of freezing in renal cancer, the human renal cancer (RCC) cell line, 786-O, was evaluated in vitro. 786-O cells were exposed to a range of freezing temperatures from -5 to -40 degrees C and compared to non-frozen controls. The data show that freezing to -5 degrees C did not affect 786-O cell viability, while -10 degrees C, -15 degrees C, and -20 degrees C results in a significant loss of viability (23, 70, and 91%, respectively). A complete loss of cell viability was evident at temperatures of -25 degrees C and colder. Following this analysis, variables involved in the success of cryoablation were investigated. For each of the temperatures tested, extended freeze hold times and passive thawing rates resulted in more extensive cell damage. Additionally, a double freeze-thaw cycle significantly increased cell death compared to a single cycle (62% vs. 22% at -10 degrees C; 89% vs. 63% at -15 degrees C, respectively). While these variables play an important part in the effective application of cryoablation, a molecular understanding of the cell death involved is critical to improving efficacy. Apoptotic inhibition afforded 12% (-10 degrees C), 25% (-15 degrees C), and 11% (-20 degrees C) protection following freezing. Using fluorescence microscopy analysis, the results demonstrated that apoptosis peaked at six hours post-thaw. Next, apoptotic initiating agents including 5-FU and resveratrol (RVT) applied prior to freezing exposure resulted in a significant increase in cell death compared to either application alone. Importantly, the combination of RVT and freezing was noticeably less effective when applied to normal renal cells. The results herein demonstrate the efficacy of freezing and describe a novel therapeutic model for the treatment of renal cancer that may distinguish between cancer and normal cells.

Targeted agents for the treatment of advanced renal cell carcinoma

Metastatic renal cell carcinoma (RCC) is currently one of the most treatment-resistant malignancies. However, the elucidation of the molecular mechanisms underlying RCC development has led to the identification of promising targets for novel therapeutic agents. The involvement of the Von Hippel-Lindau protein pathway in clear cell RCC suggests that downstream targets of this pathway, namely, signaling through vascular endothelial growth factor (VEGF) in endothelial cells, platelet-derived growth factor (PDGF) in endothelial cells and pericytes, and the epidermal growth factor receptor (EGFR) pathway in tumor cells are all reasonable and rational therapeutic targets. A number of agents are in development that target VEGF (bevacizumab, a recombinant, humanized monoclonal antibody) or its receptor, VEGFR (PTK787, SU011248, and BAY 43-9006, all of which are small molecule inhibitors). Agents targeting EGFR also are being investigated clinically (gefitinib, cetuximab, erlotinib, and ABX-EGF). The Raf/MEK/ERK pathway is an important downstream convergence point for signaling through VEGFR, platelet-derived growth factor receptor (PDGFR), and EGFR (all have receptor tyrosine kinase activity) and also has important antiapoptotic effects, thereby providing an attractive target for intervention. In addition to inhibiting VEGFR and PDGFR-mediated angiogenic pathways, BAY 43-9006 has been shown to inhibit the Raf/MEK/ERK pathway at the level of Raf kinase. MEK-directed therapeutic approaches are also in development. Given that multiple molecular pathways are implicated in tumor cell growth, antitumor activity may be increased by using individual agents that target multiple pathways, or by combining different agents to allow vertical or horizontal inhibition of relevant pathways.