OBJECTIVETo elucidate the effect of FasL gene expression on the proliferation and apoptosis of hypoxic rectal carcinoma cells.

METHODSThe normoxic expression level of FasL in HR-8348 subtype cells (HR-8348(B), HR-8348(L), HR-8348(F) and HR-8348(As)) with different invasive power were verified by Western blot. Hypoxia models for HR-8348(B), HR-8348(L), HR-8348(F) and HR-8348(As) were constructed with chemical modeling, then the FasL levels in all groups at 12 h after hypoxia were quantitated by Western blot. Distribution of different cell life cycles was determined with flow cytometry. Cell reproductive activities were detected with MTT method, and cell apoptosis was assessed with TUNEL.

RESULTSFasL protein was pigmentized at the position of 40,000 by Western blot, and the expression level of FasL was significantly higher in HR-8348(F) cells than those in HR-8348(B), HR-8348(L) and HR-8348(As) cells(F=361.149, P<0.01) in normoxia. At 12 h after hypoxia, the FasL level was also significantly higher in HR-8348(F) cells than those in other groups(F=278.766, P<0.01), but was not markedly different as compared to themselves in normoxia(t=1.762, P>0.05). The proliferation index was significantly higher in HR-8348(F)(60.43+/-3.72) than those in HR-8348(B)(40.01+/-3.30), HR-8348(L)(41.30+/-4.06) and HR-8348(As) cells(35.87+/-4.39), respectively (F=39.477,P<0.01). However, both inhibition rate of proliferation and apoptotic index were remarkably lower in HR-8348(F)(17.30+/-1.98 and 13.10+/-1.04) than those in HR-8348(B)(33.70+/-4.33 and 21.60+/-1.31), HR-8348(L)(34.20+/-3.92 and 20.10+/-1.15), and HR-8348(As)(38.00+/-4.55 and 23.90+/-1.23), respectively(F=28.811 and 76.462, respectively, P<0.01).

CONCLUSIONThe expression enhancement of intracellular FasL in rectal carcinoma in hypoxia can lead to accelerated proliferation and reduced apoptosis of cells, which will promote tumor cells to adapt microenvironmental hypoxia.