Influence of FasL gene expression on hepatic metastasis of colorectal carcinoma

BACKGROUND: FasL expression was reported to be asso- ciated with hepatic metastasis of colorectal cancer. The aim of this study was to study FasL gene expression in colorectal carcinoma and its influences on biological behavior and he- patic metastasis of colorectal carcinoma. METHODS: FasL gene expressions were examined with re- verse transcriptase-polymerase chain reaction (RT-PCR) in the primary focus of colorectal carcinoma, adjacent can- cerous mucosae, and metastasized liver focus from colorec- tal cancer. HR-8348 cells of human rectal cancer cell line were transfected with FasL cDNA. Cell growth suppression rate and response to 5-FU and carboplatin were observed and analyzed with the MTT method. RESULTS: FasL gene expression was detected in the prima- ry focus of colorectal cancer ( n = 58), adjacent cancerous mucosae ( n = 58), and metastasized hepatic tumor tissues (n =28). The positive rate of FasL expression was 24% (14/ 58), 8% (5/58), and 100% (58/58) in the primary focus, adjacent cancerous mucosae and metastasized hepatic tumor tissues respectively. FasL expression rate in the me- tastasized hepatic tumor tissues was higher than that in the primary focus (χ2 = 43.49, P<0. 01) and adjacent cance- rous mucosae (χ2=57.66, P<0.01). In a group of patients with hepatic metastasis, the FasL expression rate in primary focus was higher than that in patients without hepatic me- tastasis (χ2=3.96, P <0.05). In vitro study positive expres- sion of FasL was shown in transfected HR-8348 cells. When 5-FU or carboplatin was added, there was a significant difference in growth suppression rate between FasL positive and controlled cancer cells (t=9.02, t = 11.93, P<0.01). Under the same concentration of chemotherapeutic agents, the survival rate of FasL positive HR-8348 cells was higher than that of controlled cells. CONCLUSIONS: FasL positive cancer cells are powerfullyresistant to chemotherapeutic agents. The expression of the FasL gene in colorectal cancer cells is related to immune evasion to escape from being killed by immune cells, show- ing stronger drug-resistance, and it facilitates hepatic me- tastasis.