Overexpression of 3-phosphoinositide-dependent protein kinase-1 is associated with prognosis of gastric carcinoma.

This study investigated the correlation between the expression of 3-phosphoinositide-dependent protein kinase-1 (PDK1) and the prognosis of gastric carcinoma patients. A total of 156 paired tumor and matched normal samples were collected from patients of gastric carcinoma who underwent surgical resection. The expression of PDK1 was analyzed by real-time quantitative PCR and immunohistochemistry method. Potential correlation between PDK1 protein expression and the clinicopathological characteristics was determined by chi-square test and Spearman correlation analysis. The influence of PDK1 expression on 5-year survival rate and survival length was determined by Kaplan-Meier analysis. The expression of PDK1 mRNA and protein were significantly higher in tumor samples comparing to those in adjacent normal samples (paired t test, P = 0.007). Immunohistochemical staining results indicated that PDK1 protein level was positively correlated with infiltration (P = 0.006). However, no associations with age, sex, clinical stage, lymph node metastasis, and distant metastasis were observed (P > 0.05). The 5-year survival rate was 20.1 and 63.4 % of the patients with high and low expression level of PDK1, respectively (P < 0.05). The median survival length was 32.5 months (95 % CI 22.8-37.6) for patients with high level of PDK1 and 63.1 months (95 % CI 52.3-64.7) for patients with low level of PDK1 (×2 = 20.153, P < 0.05). Kaplan-Meier survival curves demonstrated that elevated expression of PDK1 was an independent negative prognostic factor of gastric carcinoma (P<0.05). Our study indicated that PDK1 might serve as a candidate pro-oncogene and a potential prognostic biomarker for gastric carcinoma.