nutlin-3a and Carcinoma--Renal-Cell

Sunitinib continues to be administered as a first-line therapeutic agent in metastatic renal cell carcinoma (mRCC). This study examined the potential role of p53 in sunitinib resistance and as a predictive marker in mRCC.. We analysed the effects of p53 knockout on sunitinib resistance. p53 expression in 53 mRCC patients receiving first-line sunitinib was determined immunohistochemically. We performed in silico analysis to examine the predictive value of p53 in mRCC.. WST-1 assays showed that p53 knockout decreased sensitivity to sunitinib. Sunitinib and nutlin-3 together suppressed cell growth. Immunohistochemistry revealed 11 p53-positive cases among 53 patients with mRCC. Kaplan-Meier analysis showed that p53-positive cases tended to be associated with poor progression-free survival (PFS) after first-line sunitinib treatment. In the JAVELIN 101 study, TP53 mutation was significantly associated with poor PFS after sunitinib treatment.. p53 may be involved in sunitinib resistance and represent a valuable marker for sunitinib treatment in mRCC.

Topics: Adult; Aged; Aged, 80 and over; Carcinoma, Renal Cell; Cell Proliferation; Computer Simulation; Drug Resistance, Neoplasm; Drug Synergism; Female; Gene Knockout Techniques; Humans; Imidazoles; Kaplan-Meier Estimate; Kidney Neoplasms; Male; Middle Aged; Piperazines; Progression-Free Survival; Retrospective Studies; Sunitinib; Treatment Outcome; Tumor Suppressor Protein p53; Up-Regulation

Although the role of p53 as a tumour suppressor in renal cell carcinoma (RCC) is unclear, our recent analysis suggests that increased wild-type p53 protein expression is associated with poor outcome. A growing body of evidence also suggests that p53 expression and increased co-expression of MDM2 are linked with poor prognosis in RCC. We have therefore examined whether an MDM2 antagonist; Nutlin-3, might rescue/increase p53 expression and induce growth inhibition or apoptosis in RCC cells that retain wild-type p53. We show that inhibition of p53 suppression by MDM2 in RCC cells promotes growth arrest and p53-dependent senescence - phenotypes known to mediate p53 tumour suppression in vivo. We propose that future investigations of therapeutic strategies for RCC should incorporate MDM2 antagonism as part of strategies aimed at rescuing/augmenting p53 tumour suppressor function.

Topics: Antineoplastic Agents; Carcinoma, Renal Cell; Cell Line, Tumor; Cell Proliferation; Cellular Senescence; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Kidney Neoplasms; Piperazines; Proto-Oncogene Proteins c-mdm2; RNA, Messenger; Tumor Suppressor Protein p53

The renal cell carcinoma (RCC) is one of the top 10 cancers in USA. The renal tumors are highly angiogenic and are resistant to conventional interventions, particularly radiotherapy. The advent of multi-specific tyrosine kinase inhibitor sorafenib has improved the progression-free survival in RCC, but overall survival in recurrent and metastatic RCC is still a concern that has lead to characterization of combinatorial regimens. Hence, we studied the effect of combination of nutlin-3, an MDM2 inhibitor, which increases p53 levels, and sorafenib in RCC. Sorafenib along with nutlin-3 synergistically inhibited the cell survival and enhanced caspase-3 cleavage leading to apoptosis in RCC. Nutlin-3 and sorafenib were more effective in reducing the migration of RCC, in combination than as single agents. Sorafenib and nutlin-3 decreased the phosphorylation of vascular endothelial growth factor receptor-2 (VEGFR-2) and ERK along with inducing p53 activity. The sorafenib and nutlin-3 co-treatment lead to enhanced levels of p53, p-p53, and increase in the levels of p53 pro-apoptotic effector PUMA, Bax, and decrease in the anti-apoptotic Bcl-2 levels. Importantly, our studies revealed that sorafenib alone can activate p53 in a concentration dependent manner. Thus, co-treatment of nutlin-3 with sorafenib leads to increased half-life of p53, which in turn can be activated by sorafenib, to induce downstream pro-apoptotic and anti-proliferative effects. This is the first report showing the synergistic effect of sorafenib and nutlin-3 while providing a strong clinical-translational rationale for further testing of sorafenib and nutlin-3 combinatorial regimen in human RCC.

Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; bcl-2-Associated X Protein; Benzenesulfonates; Carcinoma, Renal Cell; Caspase 3; Cell Line, Tumor; Cell Movement; Humans; Imidazoles; Kidney Neoplasms; MAP Kinase Signaling System; Niacinamide; Phenylurea Compounds; Phosphorylation; Piperazines; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-mdm2; Pyridines; Sorafenib; Tumor Suppressor Protein p53; Vascular Endothelial Growth Factor Receptor-2

Renal cell cancers (RCC) are notoriously resistant to chemotherapy and radiotherapy. While mutations of the p53 tumor suppressor gene frequently contribute to therapy resistance in other epithelial cancers, p53 mutations are relatively rare in RCC. To date, there is conflicting evidence as to whether p53 signaling and function are otherwise proficient or defective in tumors with wild-type p53. In this study, we assayed p53 function in a series of RCC cell lines and normal proximal epithelial tubule cells using two different MDM-2 antagonists, Nutlin-3a and MI-219. Most cell lines with wild-type p53 responded to MDM-2 antagonists as evidenced by induction of p53 and its target gene p21. RCC cell lines treated with MDM-2 antagonists consistently accumulated in the G2/M phase of the cell cycle and this event was associated with inhibition of proliferation in RCC cell lines but not in normal proximal epithelial tubule cells. MDM-2 antagonists did not induce significant cell death in RCC cell lines, even with induction of p53-dependent pro-apoptotic genes. In contrast, MDM-2 antagonists caused significant cell death in LNCaP prostate adenocarcinoma cells. RCC cell lines with reduced p53, either by mutation or through ectopic expression of p53 shRNA, demonstrated enhanced sensitivity to cell death following sequential treatment with DNA damage and G2/M checkpoint abrogation. Our results suggest that wild-type p53 RCC cell lines are proficient in p53-dependent cell cycle arrest but defective in p53-dependent cell death.

Topics: Apoptosis; Carcinoma, Renal Cell; Cell Cycle; Cell Death; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinase Inhibitor p21; Doxorubicin; Gene Expression Regulation, Neoplastic; Genes, p53; Humans; Imidazoles; Kidney Tubules, Proximal; Male; Mutation; Phosphorylation; Piperazines; Polymerase Chain Reaction; Prostatic Neoplasms; Proto-Oncogene Proteins c-mdm2; RNA, Small Interfering; Signal Transduction; Tumor Suppressor Protein p53