Purpose: Recently, two alternatively spliced survivin variants, survivin-ΔEx3 and survivin-2B, were identified in a single copy of the survivin gene. It has been reported that the expressions of survivin splice variants significantly correlates with the clinical results in many types of human carcinoma. We investigated the transcription levels of survivin and its splice variants in human colorectal carcinomas, and analyzed correlations between survivin expression levels and clinicopathologic features.
Methods: We used Western blot and real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) to analyze the protein and mRNA expression levels of survivin variants in 51 colorectal carcinomas. The quantitative RT-PCR was performed using primer pairs specific for survivin and each of its splice variants, then normalized for the gene that encodes glyceraldehydes-3-phosphate dehydrogenase.
Results: In Western blotting, the protein levels of survivin were higher in the tumor tissue than in normal tissue. The expression of survivin, survivin-2B and survivin-ΔEx3 mRNA was present in 96%, 64.7%, and 82.4% of the samples, respectively. When the pathologic parameters were compared, colorectal cancers of advanced pT stages showed significant decrease in survivin-2B mRNA expression by the quantitative RT-PCR (P < 0.001).
Conclusion: The decreased expression of survivin-2B might be related to tumor progression in colorectal cancers. This finding indicates that alternatively spliced variants of survivin may be involved in refining the functions of survivin during tumor progression.
Keywords: Colorectal neoplasms; Quantitative RT-PCR; Survivin variant.