Bobcat339

Vascular calcification is prevalent in chronic kidney disease (CKD), but existing medical treatments fail to achieve satisfactory therapeutic effects. Vascular calcification is now recognized as an active multifactorial process involving diverse mechanisms. Alpha-ketoglutarate (AKG), an intermediate in tricarboxylic acid cycle, has been demonstrated to extend lifespan and ameliorate age-related osteoporosis. However, whether AKG inhibits vascular calcification remains unknown.

Here, mineral deposition was studied with AKG treatment in rodent and human vascular smooth muscle cells (VSMCs) under osteogenic conditions in vivo and in vitro.

AKG treatment remarkably ameliorated calcification of rat and human arterial rings ex vivo and aortic calcification in CKD rats and mice. Mechanistically, AKG treatment upregulated DNA demethylase ten-eleven translocation 2 (TET2) expression during vascular calcification. Knockdown of TET2 by siRNA and pharmacological inhibition of TET2 by Bobcat339 promoted vascular calcification in rat VSMCs. Bobcat339 also enhanced rat aortic ring calcification. Conversely, TET2 overexpression ameliorated vascular calcification in rat VSMCs, rat aortic rings and CKD rats. Furthermore, VSMC-specific TET2 deficiency promoted aortic calcification in CKD mice. Both TET2 siRNA and Bobcat339 independently counteracted the inhibitory effect of AKG on vascular calcification of rat VSMCs. Inhibitory effect of AKG administration on vascular calcification was reduced in TET2 knockout mice. TET2 overexpression reduced the levels of the NLRP3 inflammasome pathway, cleaved Caspase-1 and IL-1β protein expression in VSMCs and NLRP3 agonist Nigericin-induced cell calcification.

Our study demonstrate that AKG attenuates vascular calcification partially via upregulation of TET2 and inhibition of NLRP3 inflammasome, indicating the critical role of epigenetic modifier in vascular calcification. Modulation of TET2 may become a promising strategy for the treatment of vascular calcification.

Hepatocellular carcinoma (HCC) is a malignancy that occurs worldwide and is generally associated with poor prognosis. The development of resistance to targeted therapies such as sorafenib is a major challenge in clinical cancer treatment. In the present study, Ten-eleven translocation protein 1 (TET1) was found to be highly expressed in sorafenib-resistant HCC cells and knockdown of TET1 can substantially improve the therapeutic effect of sorafenib on HCC, indicating the potential important roles of TET1 in sorafenib resistance in HCC. Mechanistic studies determined that TET1 and Yes-associated protein 1 (YAP1) synergistically regulate the promoter methylation and gene expression of DNA repair-related genes in sorafenib-resistant HCC cells. RNA sequencing indicated the activation of DNA damage repair signaling was extensively suppressed by the TET1 inhibitor Bobcat339. We also identified TET1 as a direct transcriptional target of YAP1 by promoter analysis and chromatin-immunoprecipitation assays in sorafenib-resistant HCC cells. Furthermore, we showed that Bobcat339 can overcome sorafenib resistance and synergized with sorafenib to induce tumor eradication in HCC cells and mouse models. Finally, immunostaining showed a positive correlation between TET1 and YAP1 in clinical samples. Our findings have identified a previously unrecognized molecular pathway underlying HCC sorafenib resistance, thus revealing a promising strategy for cancer therapy.Graphical Abstract