Cytotoxicity of Gymnopilus purpureosquamulosus extracts on hematologic malignant cells through activation of the SAPK/JNK signaling pathway

Treatment of hematologic malignancies is a formidable challenge for hematologists and there is an urgent need to identify safe and efficacious agents either via synthesis in the laboratory or isolation from natural products. Here, we report the cytotoxicity of extracts from mushroom Gymnopilus purpureosquamulosus HOil (G. pps) and describe its molecular mechanisms. Using leukemia, lymphoma and multiple myeloma cell lines, 28-35 ppm G. pps extract inhibited cell proliferation by similar to 46-79%, which correlates with activation of apoptosis as indicated by increase in annexin V-positive cells (similar to 5-8-fold), production of reactive oxygen species (similar to 2-3-fold), cells in sub G0/G1 phase (similar to 3-13-fold), caspase 3 enzymatic activity (similar to 1.6-2.9-fold), DNA fragmentation, PARP1 cleavage and down-regulation of prosurvival proteins. Mitochondrial membrane potential decreased and leakage of pro-apoptotic factors to cytoplasm was observed, consistent with the activation of intrinsic apoptosis. Western blot analysis showed activation of the ASK1-MEK-SAPK/JNK and ASK1-P38 MAPK pathways possibly due to changes in the cellular redox status as suggested by decreased protein levels of peroxiredoxin, thioredoxin and thioredoxin reductase. Moreover, antioxidant N-acetylcysteine alleviated the cytotoxicity of G. pps. Pharmacological inhibition of SAPK/JNK and P38 alleviated the G. pps-mediated cytotoxicity. The extract activated apoptosis in leukemia and lymphoma patient cell samples but not in mononuclear cells from healthy donors further supporting the therapeutic values of G. pps for hematologic malignancies.

Automated summary

The extract from mushroom Gymnopilus purpureosquamulosus HOil (G. pps) showed cytotoxic effects on leukemia, lymphoma, and multiple myeloma cell lines by inducing apoptosis. The mechanisms involve changes in cellular redox status, activation of ASK1-MEK-SAPK/JNK and ASK1-P38 MAPK pathways, and inhibition of prosurvival proteins. Antioxidants alleviated the cytotoxicity of G. pps, highlighting its potential therapeutic value for hematologic malignancies.