RESUMO
<p><b>OBJECTIVE</b>To investigate the effects of X-ray exposure on the release of soluble tumor necrosis factor receptor-p75 (sTNFR-p75) in hepatocellular carcinoma HepG2 cells in vitro.</p><p><b>METHODS</b>Enzyme-linked immunosorbent assay (ELISA) was used to examine the levels of sTNFR-p75 in the supernatants of HepG2 cells before and after X-ray exposure. The cell apoptosis was analyzed by flow cytometry and transmission electron microscope(TEM), and the morphological changes of the cells were examined under optical microscope and transmission electron microscope(TEM).</p><p><b>RESULTS</b>X-ray exposure of the cells resulted in a strong increase of cell apoptosis (P<0.05) and sTNFR-p75 production in the cells as compared with the those before the exposure (P<0.01). Optical microscopy revealed apoptotic changes of HepG2 cell after the exposure, shown as cell shrinkage, spherical cell morphology, cytoplasmic and nuclear condensation. Apoptotic bodies were detected by TEM.</p><p><b>CONCLUSION</b>X-ray exposure induces HepG2 cells apoptosis by inhibiting the release of sTNFR-p75 into the supernatant.</p>