Down-regulating Effect of a Standardized Extract of Cultured Lentinula edodes mycelia on Cortactin in Prostate Cancer Cells Is Dependent on Malignant Potential

Abstract

Background/Aim: The incidence and mortality rates of prostate cancer have been increasing worldwide. Although prostate cancer cells grow slowly in the local original site, once the cancer cells spread to distant organs they grow rapidly and show very aggressive features. Cortactin is a protein that regulates the actin cytoskeleton and plays crucial roles in cancer metastasis. Up-regulated cortactin is correlated with the metastatic capacity of prostate cancer cells. AHCC^®, a standardized extract of cultured Lentinula edodes mycelia, has been previously reported to have cortactin-down-regulating effects on human pancreatic cancer cells. In the present study, the effects of AHCC^® treatment on cortactin levels in prostate cancer cells was evaluated. Materials and Methods: LNCaP.FGC, DU145, and PC-3 are human prostate cancer cell lines. LNCaP.FGC is well differentiated, androgen-dependent, and poorly metastatic. DU145 is less differentiated, androgen-independent, and moderate metastatic. PC-3 is less differentiated, androgen-independent, and highly metastatic. The effects of AHCC^® treatment on cortactin levels in prostate cancer cells was evaluated by western blot. Results: In vitro AHCC^® treatment decreased cortactin levels in LNCaP.FGC and DU145 cells but did not change those in PC-3 cells. Conclusion: AHCC^® treatment down-regulated cortactin expression in poor and moderate metastatic LNCaP.FGC and DU145 cells but showed no effect on cortactin expression in the highly metastatic PC-3 cells. Further studies are required to elucidate the mechanism of the resistance to AHCC^® treatment in highly metastatic PC-3 cells.