Cytotoxicity of Medicinal Mushrooms Oudemansiella canarii and Ganoderma lucidum (Agaricomycetes) Against Hematologic Malignant Cells via Activation of Apoptosis-Related Markers

Cancer is the second leading cause of death worldwide, and despite of the of the availability of the advanced chemical treatments, development of effective and safe alternatives derived from natural resources are still of high interest. Mushroom is one of the important resources of pharmacologically active cytotoxic compounds. In this paper, we report the cytotoxicity of ethanolic extracts of Oudemansiella canarii (Jungh.) Höhn. and Ganoderma lucidum (W. Curt.: Fr.) P. Karst. against nine hematologic malignant cells and describe their molecular mechanisms. Cell lines were exposed to varying concentrations of mushroom extracts for 48 h and the cell proliferation and apoptosis parameters were determined. Western blot analysis was performed to determine the extract-induced changes in the level of apoptosis-related proteins in cancer cell lines and patient-derived mononuclear cells. Results revealed that O. canarii and G. lucidum extracts exhibited cytotoxicity with IC50 values of 26.8-66.0 ppm and 48.1-78.4 ppm, respectively, in all the cancer cell lines used. Mushroom extracts inhibited cell proliferation by 57.3-72.5% (O. canarii) and 44.2-67.4% (G. lucidum), which correlates to the activation of apoptosis as indicated by increased annexin V positivity, cells in sub G0/G1 phase and production of reactive oxygen species, and decreased mitochondrial membrane potential. Western blot analysis showed increase in the level of apoptotic markers (cleaved PARP1, cleaved caspase 3 and phosphorylation of histone 2AX) and activation of the stress-activated protein kinase (SAPK/JNK) signaling pathway. The extract-activated apoptosis was also observed in mononuclear cells isolated from the peripheral blood of leukemia and lymphoma patients. In conclusion, activation of pro-apoptotic markers is one of the major mechanisms of the cytotoxicity of O. canarii and G. lucidum extracts against hematologic malignant cells.