The medicinal fungus regulates DNA repair and enhances the radiosensitivity of human esophageal cancer cells.

This study investigated the adjunctive effects of mycelial fermentation broth (-MFB), a Taiwanese medicinal fungus, in enhancing the radiosensitivity of esophageal cancer cells. Human CE81T/VGH squamous and BE3 adenocarcinoma esophageal cancer cells were used in this study. A colony formation assay showed that pretreatment with -MFB decreased the survival of irradiated esophageal cancer cells, with a maximum sensitizer enhancement ratio of 1.91% and 37% survival. A DNA histogram study showed that -MFB pretreatment enhanced cell cycle arrest at the G2/M phase, the most radiosensitive phase. An immunofluorescence assay and a Western blotting assay showed that -MFB delayed the abrogation of γ-H2AX, upregulated p21 expression, and attenuated the radiation-induced phosphorylation of ataxia telangiectasia-mutated kinase and checkpoint kinase 2. An in vivo validation study showed that -MFB treatment tended to have a synergistic effect with radiation on the tumor growth delay of CE81T/VGH cells in BALB/c mice. These data suggest that this edible fungus product could enhance the effect of radiotherapy against esophageal cancer.