Synergistic roles of p53 and HIF1α in human renal cell carcinoma-cell apoptosis responding to the inhibition of mTOR and MDM2 signaling pathways.

INTRODUCTION: mTOR and MDM2 signaling pathways are frequently deregulated in cancer development, and inhibition of mTOR or MDM2 independently enhances carcinoma-cell apoptosis. However, responses to mTOR and MDM2 antagonists in renal cell carcinoma (RCC) remain unknown. MATERIALS AND METHODS: A498 cells treated with MDM2 antagonist MI-319 and/or mTOR inhibitor rapamycin were employed in the present study. Cell apoptosis and Western blot analysis were performed. RESULTS AND CONCLUSION: We found that the MDM2 inhibitor MI-319 induced RCC cell apoptosis mainly dependent on p53 overexpression, while the mTOR antagonist rapamycin promoted RCC cell apoptosis primarily through upregulation of HIF1α expression. Importantly, strong synergistic effects of MI-319 and rapamycin combinations at relatively low concentrations on RCC cell apoptosis were observed. Depletion of p53 or HIF1α impaired both antagonist-elicited apoptoses to differential extents, corresponding to their expression changes responding to chemical treatments, and double knockdown of p53 and HIF1α remarkably hindered MI-319- or rapamycin-induced apoptosis, suggesting that both p53 and HIF1α are involved in MDM2 or mTOR antagonist-induced apoptosis. Collectively, we propose that concurrent activation of p53 and HIF1α may effectively result in cancer-cell apoptosis, and that combined MDM2 antagonists and mTOR inhibitors may be useful in RCC therapy.

Protein interactions of cortactin in relation to invadopodia formation in metastatic renal clear cell carcinoma.

In the present study, we wanted to examine the predominant factor/s in the initiation of metastasis. We used samples of advanced grades of renal clear cell carcinoma with documented clinical history of vena caval spread as the experimental group. The major rationale for this selection is the fact that renal cell carcinoma metastasize extensively through the inferior vena cava up to the pulmonary bed and often exist as a continuous mass of metastatic tissue. As cortactin plays a significant role in invadopodia formation during initiation of metastasis, in the present study, we tested expression of cortactin and phospho(tyr421)-cortactin in different grades of renal cell clear carcinoma and examined its property to bind to actin. The findings of the present study suggest that the variations of the local physiological milieu are the driving forces for metastasis by enhancing molecular mechanisms for lamellipodia formation. We conclude that localization of cortactin in cancer cells and interaction between actin and its nucleators are crucial for cancer progression.

Horseshoe kidney with retrocaval ureter: one case report.

Horseshoe kidney and retrocaval ureter are uncommon congenital anomalies of the genitourinary system that are easily diagnosed by typical imaging features. Both anomalies presenting in one patient is a rare disease characterized by isthmus of horseshoe kidney between the abdominal aorta and inferior vena cava. The clinical diagnosis and treatment of horseshoe kidney with retrocaval ureter remain a challenge. Here, we reported a case of a 44-year-old man with the two anomalies who was preoperatively diagnosed by unenhanced computed tomography scanning immediately after retrograde pyelography. The literatures on such combined anomalies are reviewed and the diagnostic evaluation and surgical management of this rare entity are discussed.