Expression of survivin and its spliced variants in bladder tumors as a potential prognostic marker

ABSTRACT

Survivin, a novel inhibitor of apoptosis, is re-expressed in a vast majority of human cancers and is widely considered as a diagnostic marker of cancer. Survivin protein regulates both cell division and apoptosis. There are at least 5 sliced variants of the gene with different subcellular localization and anti-apoptotic property. We examined the expression pattern of survivin and its 2 sliced variants, survivin-delta EX 3 and survivin-2B, and their prognostic values in archival collections of formalin-fixed paraffin-embedded samples of bladder tumors. Total RNA from formalin-fixed paraffin embedded samples [51 samples from 30 patients with bladder cancer and 5-year follow-up] were extracted and analyzed by semiquantitative reverse transcriptase polymerase chain reaction technique. Tissue distribution and subcellular localization of survivin protein in tumor tissues was also examined by immunohistochemistry. The expression of survivin, survivin-delta Ex3, and surviving-2B were detected in 66.6%, 47.8%, and 54.7% of the specimens, respectively. The expression of survivin and survivin-delta Ex3 were preferentially elevated in tumours with higher grades, whereas survivin-2B expression was lower in high-grade tumors [P=.04]. A reverse correlation was observed between survivin-2B expression and high-grade tumors. Immunohistochemistry results also confirmed the nuclear localization of survivin protein within tumoral cells. We were successful in detecting the expression of survivin and its variants in formalin-fixed paraffin-embedded bladder samples. Furthermore, our results showed that overexpression of survivin and survivin-delta Ex3 in bladder tumors correlates with poor prognosis of bladder cancer. We suggest that survivin and its variants are suitable prognostic markers of bladder tumors