OBJECTIVETo study FasL gene expression in colorectal carcinoma and its influences on biological behaviour of colorectal cancer and hepatic metastasis.

METHODSFasL gene expressions were examined with RT-PCR technique in the primary locus of colorectal cancer, mucosa adjacent to cancer, and hepatic metastasis. HR-8348 cells of human rectal cancer cell line were transfected with FasL cDNA. Cell growth suppression rates and cell response to 5-FU and carboplatin were observed and analysed with MTT method.

RESULTSFasL gene expressions were detected in the primary site of colorectal cancer (n = 58), cancer adjacent mucosa (n = 58), and hepatic metastasis (n = 28). The positive rate of FasL expression was 24% (14/58), 14% (8/58), 100% (28/28), respectively, in primary site, tumor adjacent mucoca and hepatic metastasis. FasL expression rate in hepatic metastasis was higher than that in the primary site (chi2 = 43.49, P < 0.01) and tumor adjacent mucosa (chi2 = 57.66, P < 0.01). In a group of patients with hepatic metastasis, FasL expression rate in primary site was higher than that in patients without hepatic metastasis (chi2 = 3.96, P < 0.05). In vitro experiment, positive expression of FasL was found 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 control cancer cells (t = 9.02, t = 11.93, P < 0.01). Under same concentration of chemotheraputic agent, survival rate of FasL positive HR-8348 cells was higher than that of control cells.

CONCLUSIONSFasL positive cancer cells have more powerful resistance to chemotheraputic drugs. Expression of FasL gene in colorectal cancer cells is related with immune evasion to escape killing by immune cells, showing stronger drug-resistance, and it facilitates hepatic metastasis.