p53β: a new prognostic marker for patients with clear-cell renal cell carcinoma from 5.3 years of median follow-up.

We previously reported six different p53 isoforms in renal cell carcinoma (RCC). In the present study, influences of p53β on recurrence-free survival (RFS) and overall survival (OS) were evaluated. Patients diagnosed with RCC in our center were into this study. mRNA expressions of p53 isoforms (p53α, p53β, p53γ) in tumors were determined by RT-PCR and real-time PCR. Functional yeast-based assay was performed to analyze p53 mutational status. p53β transfected 786-O and CAKi-1 cells were cultured to examine expressions of B-cell lymphoma 2-associated X protein (bax) and caspase-3, and ratios of apoptosis. After surgeries, all patients were followed up at programmed intervals. 266 patients were analyzed in this study. Median follow-up time was 5.3 years. RT-PCR (r = -0.72, P = 0.016) and real-time PCR (r = -0.65, P = 0.033) both showed only p53β expressed higher level in lower tumor stage versus higher stage. p53 wild-type and p53 mutation had comparable RFS (P = 0.361) and OS (P = 0.218), respectively. Kaplan-Meier analysis showed high p53β expression was associated with significantly improved RFS and OS, regardless of p53 mutational status. High p53β expression indicated better RFS [hazard ratio (HR) 2.599, 95% confidence interval (CI) 1.472-4.551, P = 0.038] and OS (HR 2.604, 95% CI 1.453-4.824, P = 0.031). p53β transfected 786-O and CAKi-1 cells expressed significantly higher level of bax and caspase-3, and had higher ratios of apoptosis than untransfected cells. Taken together, higher level of p53β predict better prognosis in patients with RCC through enhancing apoptosis in tumors.