Survivin-3B gene decreases the invasion-inhibitory effect of colon cancer cells with 5-fluorouracil.

The expression of survivin molecules has been confirmed in many types of cancer cells, including colon cancer cells, and they are considered important antiapoptotic molecules. Recent studies have revealed the existence of different splicing forms of survivin molecules; however, no studies have examined their expression in gastrointestinal cancers. In 2004, we reported the existence of the survivin-3B gene, a novel splice variant of survivin. In this study, we investigated the relationship between human colon cancer and our recently cloned survivin-3B gene with a coding region of 594 bp. In the first examination, survivin-3B expression was analyzed by RT-PCR in human colon cancer and adjacent normal mucosal tissues. The associations of its expression status with clinicopathological parameters and the prognosis were also examined. Survivin-3B mRNA expression was observed in 37 (46.3%) of 80 primary colon cancers, but not in the adjacent normal colonic mucosal tissue. The rate of survivin-3B gene expression was significantly higher in colon cancer with serosal invasion. The 5-year survival rate of patients with survivin-3B gene-positive primary colon cancer was significantly poorer, at 48.7%, than that (75.4%) of survivin-3B gene-negative patients. In the second examination, after the introduction of the survivin-3B gene into cells of the colon cancer cell line DLD-1, 5-fluorouracil-induced changes in their invasive capacity was examined. The invasion-inhibitory effect of 5-fluorouracil on survivin-3B gene-transfected DLD-1 cells was significantly lower than their empty vector gene-transfected counterparts. We speculate that survivin-3B expression in colon cancer is an important factor involved in the invasive capacity of cancer cells in the presence of anticancer drug.