Expression Of CFLIP In Colorectal Cancer And Its Modulation Effect On The Apoptosis Of Colon Cancer Cells

Objective1. To investigate the expression of cFLIP_L in colorectal cancer cells both in mRNA and protein levels and its roles in the pathogenesis of colorectal cancer.2. To find the modulation effect of Actinomycin D(Act D) on the expression of cFLIP_L in colorectal cancer and subsequent effect on the apoptosis in cancer cells. Methods1. RT-PCR and Western blot were employed to detect the expression of cFLIP_L in 3 colorectal cancer cell lines and 43 specimen of colorectal cancer and matched normal mucosa.2. The immunohitochemistry technique was applied to examine the expression of cFLIP_L protein in 43 specimen of colorectal cancer and paired normal mucosa. 3. Western blot, Flow cytometry and MTT assay were employed to detect the expression of cFLIP_L and its effect on apoptosis in SW620 cell line pretreated with Act D in lower concentration.Results1. cFLIP_L mRNA and protein was positively expressed in SW1116 and SW620 cell lines and negative in LoVo cell line. All specimen of colorectal cancer and paired normal mucosa expressed cFLIP_L transcripts.2. cFLIP_L protein expression of variable intensity and extent was detected in the normal colorectal mucosa and adenocarcinomas. The mean expression scores in normal mucosa ranged from 0 to 2.95(1.55±0.86); 4.7%(2/43) of all cases were unstained and 20.9%(9/43)showed a weakly stained pattern(0significant(p<0.01). The extent of cFLIP_L expression in tumors was independent of Duke's stage, degree of differentiation, lymph and hepatic metastasis.3. The cFLIP_L expression was decreased by Act D in SW620 cell lines. After incubated with Act D(10ng/ml) for 24h, the intracellular concentration of cFLIP_L was decreased from 94.4% to 71.8% and in the mean time, the anti-Fas(1ug/ml) can induce 30% apoptosis of SW620 cells.Conclusion1. cFLIP_L was expressed in SW1116 and SW620 cell lines and the specimen of colorectal adenocarcinomas and matched normal mucosa. The expression level of cFLIP_L in adenocarcinomas was much higher than that in paired normal mucosa. Overexpression of cFLIP_L was a tumor-specific phenomenon, which can provide a selective growth advantage for colorectal cancer cells to escape death receptor-mediated apoptosis.2. Act D treatment can decrease the expression level of cFLIP_L in vitro and restore the susceptibility to Fas-induced apoptosis in colorectal cancer cells. cFLIP_L may become a new target in colorectal cancer management.