Expression and clinical significance of thymidylate synthase and adenosine triphosphate-binding cassette superfamily G member protein in advanced gastric carcinoma

Abstract

Objective To investigate the expressions of thymidylate synthase （TS） and adenosine triphosphate （ATP）-binding cassette superfamily G member 2 （ABCG2） in advanced gastric cancer （GC） and to explore their correlation with clinical pathological features. Methods A total of 80 surgical specimens of advanced gastric cancer patients were collected. The expressions of TS and ABCG2 in gastric cancer tissues and adjacent normal gastric tissues were detected by immunohistochemical method. The expression of P-glycoprotein in gastric cancer tissues was also examined. The correlations between TS, ABCG2 and clinical pathological features and P-glycoprotein were analyzed. Chi-square test was performed for two groups comparison and Kruskal-Wallis H test were used for multi-groups comparison. Results The positive rates of both TS and ABCG2 in gastric cancer tissues [85.0% （68/80） and 90.0% （72/80）] were higher than those of adjacent normal gastric tissues [62.5% （50/80） and 78.7 ~ （63/80）], the differences were statistically significant （X^2= 11. 466 and 16. 463,P= 0. 009 and 0. 001）. There were close correlation between the expression of TS, ABCG2 andtumor TNM stage,differentiation status,invasion depth （TS：X^2 = 30. 686, 61. 470 and 40. 545; ABCG2 ：X^2=48. 192, 63. 150 and 47. 512% all P%0. 01）. The later the tumor staged, the worse the cells differentiated and the deeper the tumor invaded, the higher level they expressed. Both TS and ABCG2 expressions in gastric cancer tissues were correlated with the expression level of P-glyeoprotein （X^2 =43.977 and 29. 509, both P〈0. 01）. Conclusion TS and ABCG2 may be potential indexes to predict the degree of malignancy, progression, drug resistance and prognosis in gastric cancer. Key words: Stomach neoplasms; Telomerase; ATP-binding cassette transporters; Drugtolerance; Prognosis