Expression of TROP2 mRNA in left-sided and right-sided colon cancer and its clinical significance

Abstract

To investigate the expression of TROP2 in the left-sided and right-sided colon cancer and its clinical significance. A total of eighty patients, who received radical resection of colon cancer between June 2001 and April 2005 and were staged as II( and III(, were identified, including forty with left-sided colon cancer(LSCC) and forty with right-sided colon cancer (RSCC). The expression of TROP2 was detected by real-time quantitative RT-PCR in paired cancer and normal tissue. Subsequently, the relationship between TROP2 expression and clinicopathological variables as well as the effect on the patients' prognosis were analyzed. The expression of TROP2 mRNA in the cancer tissue was significantly higher than that in normal tissue(P<0.01, paired Wilcoxon test). However, its expression in LSCC was markedly higher than that in RSCC with significant difference (P=0.009, Mann-Whitney U test). The patients with TROP2 high expression were found more frequently in LSCC than in RSCC(67.5% vs 32.5%, P=0.002, chi(2) test). Cancer-related mortality of the patients with TROP2 high expression was four times as high as low expression(40% vs 10%, P=0.002, chi(2) test). From the stratified survival analysis through Kaplan-Meier curve, the TROP2 high expression group had a significantly poorer median survival time than the low expression group for the patients with LSCC(45.9:63.1 months, P=0.032, log-rank test). By contrast, for the patients with RSCC, TROP2 expression had no marked effect on the survival time(P=0.235, log-rank test). In multivariable analysis, for the cohort of the present study, serosal invasion and lymphatic/vascular invasion were the independent prognostic factors of RSCC. Serosal invasion, lymph node metastasis and lymphatic/vascular invasion were the independent prognostic factors of LSCC. TROP2 high expression showed marginal significance(RR:6.244, 95% CI:0.755-51.636, P=0.089). (1)TROP2 is a differentially expressed gene between RSCC and LSCC. (2)TROP2 high expression is closely related to the factors indicating poor prognosis. (3)TROP2 has distinct clinical significance to the patients with different tumor sites. TROP2 high expression is potentially an independent prognostic factor of LSCC. (4)LSCC and RSCC seem to be two distinct diseases with significant molecular heterogeneity.