Radioprotective effects of Antrodia cinnamomea are enhanced on immune cells and inhibited on cancer cells.

UNLABELLED

Abstract Purpose: The radioprotective effects of Antrodia cinnamomea (AC) were investigated for understanding the potential usefulness of AC as an adjunct treatment for reducing radiation side-effects.

MATERIALS AND METHODS

In this study, we determined the ability of AC extracts (AC539) to reduce radiation side-effects by analyzing cellular viability in normal mouse spleen immune cells and human cancer cells with different radiosensitivity. We further detected the effect of AC on radiation-induced changes in cytokine- and inflammatory-related gene expressions. Furthermore, apoptosis assay was performed to determine whether AC could inhibit radiation-induced cytotoxicity.

RESULTS

We found that an AC dose of 100-150 μg/ml in a time-dependent manner was the most effective in blocking radiation-induced cytotoxicity, in vitro. Radiation-induced cytotoxicity was inhibited in spleen immune cells by 37-56%; however, pretreatment of human colorectal cancer cell line HT-29 with AC did not have any effect on radiation-induced cytotoxicity, while pretreatment of radiosensitive human breast cancer cell lines BT-474 with AC caused a moderate enhancement of radiation-induced damage. Furthermore, AC pretreatment differentially regulated the mRNA expression of several important immunomodulatory genes in response to irradiation in normal and cancer cells.

CONCLUSIONS

Our data indicate that AC may inhibit important immunoregulatory signaling which could be vital in the avoidance of an over-activated cytotoxic and inflammatory response of the immune system caused by radiation-induced tissue damage. Additionally, AC does not provide a radioprotective effect to tumor cells but instead enhances radiation-induced inflammation and cytotoxicity in cancer.