MELK promotes HCC carcinogenesis through modulating cuproptosis-related gene DLAT-mediated mitochondrial function.

ABSTRACT

Cuproptosis caused by copper overload is mediated by a novel regulatory mechanism that differs from previously documented mechanisms regulating cell death. Cells dependent on mitochondrial respiration showed increased sensitivity to a copper ionophore elesclomol that induced cuproptosis. Maternal embryonic leucine zipper kinase(MELK) promotes tumorigenesis and tumor progression through the PI3K/mTOR pathway, which exerts its effects partly by targeting the pyruvate dehydrogenase complex(PDHc) and reprogramming the morphology and function of mitochondria. However, the role of MELK in cuproptosis remains unclear. Here, we validated that elevated MELK expression enhanced the activity of PI3K/mTOR signaling and subsequently promoted Dihydrolipoamide S-Acetyltransferase (DLAT) expression and stabilized mitochondrial function. This regulatory effect helped to improve mitochondrial respiration, eliminate excessive intracellular reactive oxygen species (ROS), reduce intracellular oxidative stress/damage and the possibility of mitochondria-induced cell fate alternations, and ultimately promote the progression of HCC. Meanwhile, elesclomol reduced translocase of outer mitochondrial membrane 20(TOM 20) expression and increased DLAT oligomers. Moreover, the above changes of MELK to HCC were abolished by elesclomol. In conclusion, MELK enhanced the levels of the cuproptosis-related signature(CRS) gene DLAT (especially the proportion of DLAT monomer) by activating the PI3K/mTOR pathway, thereby promoting elesclomol drug resistance, altering mitochondrial function, and ultimately promoting HCC progression.