Effects of a spiroketal compound Peniciketal A and its molecular mechanisms on growth inhibition in human leukemia.

Peniciketal A (Pe-A), a spiroketal compound, is isolated from the saline soil-derived fungus Penicillium raistrickii. However, the underlying molecular mechanistic basis for the effects of Pe-A on leukemia is poorly understood. Here, we investigated that Pe-A reduced cell proliferation in three leukemia cell lines (THP-1, K562 and HL60). Importantly, Pe-A showed little cytotoxicity in primary mouse embryonic fibroblast (MEF) cells in a long-duration treatment. For the mechanistic research, we identified 3449 differentially expressed Pe-A-induced proteins through liquid chromatography-tandem mass spectrometry (LC-MS/MS) with TMT label in THP-1 cells. Results showed that many identified proteins were involved in apoptosis and/or autophagy. Then, we confirmed that Pe-A induced not only apoptosis via the mitochondrial pathway but also cytoprotective autophagy by activating the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathway indeed. In addition, Pe-A also arrested the cell cycle at the G0-G1 phase by regulating the expressions of checkpoint protein. Collectively, these results provide new insights into the mechanisms that Pe-A may target autophagy-related or apoptosis-related pathways to suppress the development of human leukemia.