Abstract: Abstract： Objective To detect the expression of stem cell marker Sox2 in gastric cancer (GC). Methods The mRNA and protein expressions of Sox2 in paired primary tumor tissues and their matching, adjacent non-cancerous tissues in a series of 60 cases of human GC were examined by reverse transcription-PCR (RT-PCR) and immunohistochemistry (IHC). χ2 test was used to analyze the correlation of Sox2 expression with clinicopathological parameters of GC tissues including age, gender, tumor size, histological type, TNM stage, differentiation degree, depth of invasion and lymph node metastasis. Results RT-PCR results showed that the positive rate of Sox2 expression was significantly increased in gastric tumor tissues (53.3%, 32/60) compared with that of matching, adjacent non-cancerous tissues (20.0%, 12/60, P＜0.01). Semi-quantitative analysis showed that the relative intensity of Sox2 mRNA expression was significantly higher in gastric cancer tissues (0.724±0.209) than that in tissues adjacent to carcinoma (0.256±0.065， P＜0.01). The positive expression of Sox2 was significantly higher in gastric tumor tissues (50.0%, 30/60) than that of matching, adjacent non-cancerous tissues (16.7%, 10/60， P＜0.01). The positive expression of Sox2 was significantly higher in gastric tumor patients with TNM stage (Ⅲ＋Ⅳ) than that of TNM stage (Ⅰ＋Ⅱ). The positive expression of Sox2 was significantly higher in gastric tumor patients with low differentiation and undifferentiated tumor cells than that of patients with middle and high differented cells. The positive expression of Sox2 was also significantly higher in gastric tumor patients with the depth of invasion T3-T4 than that of patients with T1- T2. The positive expression of Sox2 was significantly higher in gastric tumor patients with lymph node metastasis than that of patients without lymph node metastasis (P＜0.05 or P＜0.01). Conclusion The elevated expression of Sox2 is associated with the initiation, invasion, progression, and metastasis of GC. Sox2 may serve as a novel diagnostic and therapeutic marker for human GC.

Key words: stomach neoplasms, neoplastic stem cells, genes, tumor suppressor, immunohistochemistry, reverse tran? scriptase polymerase chain reaction, SRY-related HMG-box gene 2