PIK3CA gene mutations and amplifications in uterine cancers, identified by methods that avoid confounding by PIK3CA pseudogene sequences

Abstract

PIK3CA codes for a Class IA p110-alpha catalytic subunit of the PI3Ks (phosphatidylinositol 3-kinases) that regulate various signaling pathways important for neoplasia, including cell proliferation, motility, adhesion, and survival. Pro-oncogenic mutations in exons 9 and 20 of the PIK3CA gene have been frequently observed in numerous types of human malignancies. Amplification of the PIK3CA gene has been reported in uterine cervical cancers. In this study, we have done in depth analysis of uterine cervical and endometrial cancers for PIK3CA gene mutations and amplifications. In uterine cervical cancers, PIK3CA mutations were found in 3 of 22 cases (14%), all of them in exon 9. In endometrial cancers, a similar incidence of mutations was found, in 3 of 29 cases (10%), however they were all within exon 20. Amplification of the PIK3CA gene was also detected in 2 out of 22 (9%) cervical cancers and 3 out of 29 (10%) endometrial cancers. In this study, we were unable to find a clear association between PIK3CA mutations and gene amplifications, nor with tumor histological subtypes or staging. Mutations and amplifications of the PIK3CA gene are relatively infrequent in human cervical and endometrial cancers; however, PIK3CA gene alteration may still play a role in some subset of uterine cancers.