Copy number loss of variation_91720 in PIK3CA predicts risk of esophageal squamous cell carcinoma.

PURPOSE Esophageal squamous cell carcinoma (ESCC) is one of the most fatal cancers worldwide. However, the etiology is complex and unclear. 3q26 harboring abundant oncogenes have been identified as the loci of ESCC susceptibility. In the present study, we examined whether CNVs on 3q26 would be associated with the risk, TNM stage and prognosis of ESCC. METHODS Variation_91720 in phosphatidylinositol 3-kinase catalytic subunit (PIK3CA) and Variation_91733 in sex-determining region Y-box 2 overlapping transcript (SOX2OT) were selected for investigation. The study included 204 ESCC patients and 208 healthy controls. The copy number of the selected sites and mRNA was detected by real-time fluorescence quantitative polymerase chain reaction and calculated using the CopyCaller v2.0 software program. RESULTS The copy number distribution of Variation_91720 was significantly different in ESCC cases and matched controls (p<0.001). Copy number loss of Variation_91720 may increase the risk of ESCC (OR=6.217, 95% CI=3.117-12.400; adjusted OR =6.251, 95% CI=3.130-12.428). PIK3CA mRNA expression was higher in tumor tissue (P=0.0003) and increased with the copy number gain of Variation_91720. CONCLUSION Our findings suggest that copy number loss of Variation_91720 in PIK3CA predicts risk of ESCC, which might serve as a biomarker that for early diagnosis of ESCC.