RESUMEN
One of the distinct hallmarks of cancer cells is aerobic glycolysis (Warburg effect). Lactate dehydrogenase A (LDHA) is thought to play a key role in aerobic glycolysis and has been extensively studied, while lactate dehydrogenase C (LDHC), an isoform of LDHA, has received much less attention. Here we showed that human LDHC was significantly expressed in lung cancer tissues, overexpression of Ldhc in mice could promote tumor growth, and knock-down of LDHC could inhibit the proliferation of lung cancer A549 cells. We solved the first crystal structure of human LDHC4 and found that the active-site loop of LDHC4 adopted a distinct conformation compared to LDHA4 and lactate dehydrogenase B4 (LDHB4). Moreover, we found that (ethylamino) (oxo)acetic acid shows about 10 times selective inhibition against LDHC4 over LDHA4 and LDHB4. Our studies suggest that LDHC4 is a potential target for anticancer drug discovery and (ethylamino) (oxo)acetic acid provides a good start to develop lead compounds for selective drugs targeting LDHC4.
RESUMEN
Lipotoxicity,caused by intracellular lipid accumulation,accelerates the degenerative process of cellular senescence,which has implications in cancer development and therapy.Previously,camitine palmi-toyltransferase 1C (CPT1C),a mitochondrial enzyme that catalyzes carnitinylation of fatty acids,was found to be a critical regulator of cancer cell senescence.However,whether loss of CPT1C could induce senescence as a result of lipotoxicity remains unknown.An LC/MS-based lipidomic analysis of PANC-1,MDA-MB-231,HCT-116 and A549 cancer cells was conducted after siRNA depletion of CPT1C.Cellular lipotoxicity was further confirmed by lipotoxicity assays.Significant changes were found in the lipidome of CPT1 C-depleted cells,including major alterations in fatty acid,diacylglycerol,triacylglycerol,oxidative lipids,cardiolipin,phosphatidylglycerol,phosphatidylcholine/phosphatidylethanolamine ratio and sphingomyelin.This was coincident with changes in expressions of mRNAs involved in lipogenesis.Histological and biochemical analyses revealed higher lipid accumulation and increased malondialde-hyde and reactive oxygen species,signatures of lipid peroxidation and oxidative stress.Reduction of ATP synthesis,loss of mitochondrial transmembrane potential and down-regulation of expression of mito-chondriogenesis gene mRNAs indicated mitochondrial dysfunction induced by lipotoxicity,which could further result in cellular senescence.Taken together,this study demonstrated CPT1C plays a critical role in the regulation of cancer cell lipotoxicity and cell senescence,suggesting that inhibition of CPT1C may serve as a new therapeutic strategy through induction of tumor lipotoxicity and senescence.
RESUMEN
MTH1 enzyme belongs to the family of Nudix hydro-lases, which can prevent the oxidative damage of nucleic acid by cleaning up oxidized purine nucleotides .Close relationships were found between the activity of MTH 1 and neurodegenerative dis-eases, anti-aging et al.In recent years, MTH1 has been regar-ded as a new promising target for cancer treatment , because it plays an essential role in tumor growth , survival , invasion and metastasis.The transcription and translation , structure, catalyt-ic mechanism, detection and application of MTH1 were de-scribed, as well as various MTH1 inhibitors.