Cancer-associated splicing variants of the CDCA1 and MSMB genes expressed in cancer cell lines and surgically resected gastric cancer tissues

Background. Alternative splicing is a molecular mechanism by which different combinations of exons can be alternatively spliced to produce different mRNA isoforms. Recently, several databases have been published to predict the alto-native splicing of mRNA; cancer-specific alternative splicing has also been predicted with these databases. Those variants may be potentially useful targets for cancer therapy, however, the accuracy and veracity of these databases have yet to be confirmed. Methods. In this study, we analyzed 17 genes by reverse transcriptase-polymerase chain reaction (RT-PCR) that were predicted to have cancer-specific alternative splicing by using the splicing database, the Alternative Splicing Annotation Project (ASAP) by Lee et al, between 38 cancer cell lines from various organs and 9 corresponding normal tissues. By designing 2 types of prime sets for RT-PCR including (1) primers flanking the alternatively spliced exons and (2) primers spanning the exon/exon. junctions, cancer-associated splicing variants were investigated. Results. The alternatively splicing events were detected in 15 of 17 genes (88%); 35 of 43 variants (81%) were detected successfully with RT-PCR. Among these variants, M-RIP, HYAL2, CDCA1, and MSMB genes showed differential expressions between cancer cell lines and corresponding normal tissues. Furthermore, RTPCR with surgically resected gastric cancer tissues (diffuse type, 6; intestinal type, 4) confirmed that 2 variants of CDCA1 were upregulated in cancer tissues, whereas both variants of MSMB were expressed predominantly in normal tissues. Conclusion. Alternative splicing variants, especially in CDCA1, were detected in this study and may be potentially useful as diagnostic markers and/or novel targets for anticancer therapy. (Surgery 2009;145:57-68.)