Hepatocellular carcinoma (HCC) accounts for approximately 90% of liver cancer cases. Few therapeutic options are available for HCC patients due to intrinsic drug resistance or the low efficacy of conventional chemotherapeutic drugs, including genotoxic agents. We previously demonstrated that adipose triglyceride lipase (ATGL) is downregulated in HCC and shows anti-neoplastic activity by affecting sensitivity to different therapeutic approaches. On the basis of this evidence, we assessed the contribution of ATGL activity to the modulation of the DNA damage response induced by genotoxic drugs. We modulated ATGL expression via overexpression and silencing in the presence of etoposide and doxorubicin, which are genotoxic drugs. The catalytic activity of ATGL was abrogated by a selective inhibitor (ATGListatin) or the overexpression of the ATGL catalytic mutant. To assess the DNA damage response, we evaluated the phosphorylation of H2AX histones and the post-translational modifications of p53. The sensitivity to genotoxic drugs was assessed by analyzing cell viability and molecular markers associated with cell cycle arrest and cell death. Our results demonstrate that ATGL enhances DNA damage in HCC cells in response to genotoxic stimuli. The underlying molecular mechanism involves ATGL-mediated activation of PPARα/p300 signaling. As a result, we observed an imbalance in p53 acetylation/phosphorylation status that restrains cell cycle arrest and DNA damage repair while promoting apoptotic cell death. In line with the in vitro findings, bioinformatic analyses revealed a strong correlation between ATGL and the PPARα/p300 axis and further demonstrated an enrichment of gene sets associated with cell cycle regulation and DNA damage response in ATGL-high HCC. In conclusion, ATGL levels can be used as a predictive marker of HCC sensitivity to genotoxic insults. The activation of this lipase, or downstream molecular signaling, may thus be exploited to increase the efficacy of chemotherapeutic treatments in HCC.

Huntington’s disease (HD) is a neurodegenerative disorder caused by the expansion of the CAG trinucleotide in the exon 1 of the huntingtin gmodellerene. This abnormal expansion produces a mutant huntingtin (mHTT) protein with extended polyglutamine (polyQ) tracts. Although the molecular mechanisms underlying HD onset and progression remain poorly understood, aberrant folding, aggregation, and membrane interactions of mHTT are considered central to disease pathogenesis. In this study, we used molecular dynamics (MD) simulations to investigate the structural properties, dimerization propensity, and membrane lipid interaction of mHTT carrying 70 polyQ repeats (mHTT-Q70). Our analyses revealed that mHTT-Q70 retains partially structured α-helical conformations with increased flexibility within the polyQ domain, thus being predisposed to misfolding. Coarse-grained MD simulations further revealed a strong tendency of mHTT-Q70 to dimerize, indicating that early oligomerization may represent a critical step in protein aggregation. Interestingly, we show that membrane cholesterol content dose-dependently promotes dimeric mHTT-Q70—but not monomeric mHTT-Q70—association with neuronal membrane models, which was observed for 70% of simulation time at 40% cholesterol content. Such a cholesterol-dependent membrane binding of dimeric mHTT-Q70 suggests that membrane lipid composition may represent a critical checkpoint in the early stages of mHTT-Q70 aggregation, and of cytotoxicity thereof. Moreover, distinct neuronal membrane lipids like phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine differently contributed to mHTT-Q70 binding, highlighting the complexity of such a lipid-dependent modulation. Taken together, these findings underscore the dynamic interplay between polyQ-driven misfolding, dimerization, and membrane lipids in HD pathogenesis, suggesting that modulation of membrane composition, and in particular of cholesterol levels, may be a novel action point to design therapeutic drugs for HD.