Effect of transforming growth factor-alpha on enterocyte apoptosis is correlated with EGF receptor expression along the villus-crypt axis during methotrexate-induced intestinal mucositis in a rat

The purpose of the present study was to evaluate the effect of transforming-growth factor-alpha (TGF-α) on enterocyte apoptosis following methotrexate (MTX) induced intestinal mucositis in a rat and in Caco-2 cells. Non-pretreated and pretreated with MTX Caco-2 cells were incubated with increasing concentrations of TGF-α. Cell apoptosis was determined by FACS cytometry. Adult rats were divided into four groups: Control, Control-TGF-α, MTX, and MTX- TGF-α rats. Three days later rats were sacrificed. Enterocyte apoptosis were measured at sacrifice. RT-PCR and Western Blotting was used to determine the level of Bax and Bcl-2 mRNA and protein. Real time PCR was used to measure epidermal growth factor receptor (EGFr) expression along the villus-crypt axis. The in vitro experiment has shown that treatment with TGF-α of Caco-2 cells results in a significant inhibition of cell apoptosis in a dose-dependent manner. In vivo experiment, a decreased levels of apoptosis in MTX- TGF-α rats corresponded with the decrease in Bax and with the increase in Bcl-2 at both mRNA and protein levels. The inhibiting effect of TGF-α on enterocyte apoptosis was strongly correlated with EGFr expression along the villus-crypt axis. In conclusion, treatment with TGF-α inhibits enterocyte apoptosis following MTX- injury in the rat.