PIK3CA at 3q26, which encodes the p110α catalytic subunit of phosphatidylinositol (PI) 3-kinasePI3-kinase, is a unique intracellular signal transducer characterized by its lipid substrate specificity. A recent study has provided convincing evidence that PIK3CA is an oncogene in ovarian cancer and cervical cancer and is associated with progression of dysplasia into invasive squamous cell carcinoma in the head and neck. Although it has been reported that PIK3CA plays a critical role in several cancers, it remains unclear whether PIK3CA affects esophageal squamous cell carcinoma (ESCC). The purpose of this study is to clarify the expression of PIK3CA in esophageal squamous cell carcinoma. The PIK3CA mRNAs were examined in 37 surgical specimens of ESCC as determined by quantitative RT-PCR, and the mean mRNA of PIK3CA was 2.61 fold higher compared with non-tumor human esophageal surface epithelial cells (P<0.001). Immunohistochemically, 29 resected specimens of ESCC were analyzed, and 26 of 29 specimens (89.7%) were detected with weak (13cases) and strong (13 cases) staining localized to tumor cells of islets. Comparing weak and strong staining for PIK3CA, the presence of node metastasis and advanced stage were significantly correlated with strong staining for PIK3CA (P < 0.05). These findings suggest that PIK3CA may play an important role on the development of ESCC and that it may be also related to nodal metastasis.

98th AACR Annual Meeting-- Apr 14-18, 2007; Los Angeles, CA