Valproic acid sensitizes metformin-resistant human renal cell carcinoma cells by upregulating H3 acetylation and EMT reversal

Abstract

BackgroundMetformin (Met) is a widely available diabetic drug and shows suppressed effects on renal cell carcinoma (RCC) metabolism and proliferation. Laboratory studies in RCC suggested that metformin has remarkable antitumor activities and seems to be a potential antitumor drug. But the facts that metformin may be not effective in reducing the risk of RCC in cancer clinical trials made it difficult to determine the benefits of metformin in RCC prevention and treatment. The mechanisms underlying the different conclusions between laboratory experiments and clinical analysis remains unclear. The goal of the present study was to determine whether long-term metformin use can induce resistance in RCC, whether metformin resistance could be used to explain the disaccord in laboratory and clinical studies, and whether the drug valproic acid (VPA), which inhibits histone deacetylase, exhibits synergistic cytotoxicity with metformin and can counteract the resistance of metformin in RCC.MethodsWe performed CCK8, transwell, wound healing assay, flow cytometry and western blotting to detect the regulations of proliferation, migration, cell cycle and apoptosis in 786-O, ACHN and metformin resistance 786-O (786-M-R) cells treated with VPA, metformin or a combination of two drugs. We used TGF-β, SC79, LY294002, Rapamycin, protein kinase B (AKT) inhibitor to treat the 786-O or 786-M-R cells and detected the regulations in TGF-β /pSMAD3 and AMPK/AKT pathways.Results786-M-R was refractory to metformin-induced antitumor effects on proliferation, migration, cell cycle and cell apoptosis. AMPK/AKT pathways and TGF-β/SMAD3 pathways showed low sensibilities in 786-M-R. The histone H3 acetylation diminished in the 786-M-R cells. However, the addition of VPA dramatically upregulated histone H3 acetylation, increased the sensibility of AKT and inhibited pSMAD3/SMAD4, letting the combination of VPA and metformin remarkably reappear the anti-tumour effects of metformin in 786-M-R cells.ConclusionsVPA not only exhibits synergistic cytotoxicity with metformin but also counteracts resistance to metformin in renal cell carcinoma cell. The re-sensitization to metformin induced by VPA in metformin-resistant cells may help treat renal cell carcinoma patients.

Histone deacetylase inhibitors dysregulate DNA repair proteins and antagonize metastasis-associated processes

“…These data are coherent with previous reports that show beneficial effects of HDACi against RCC cells and EMT (Chun 2018;Jones et al 2009a, b;Juengel et al 2014;Mao et al 2017). Furthermore, HDACi counteracted the acquired resistance of RCC cells against the mammalian target of rapamycin-inhibitor everolimus and the glucose-regulating biguanide metformin (Juengel et al 2014;Wei et al 2018). In light of the chemoresistance and the poor prognosis of metastatic RCC (Barbieri et al 2017;Chang et al 2019), these findings suggest that HDACi pose an interesting therapeutic option for this cancer type.…”

Resveratrol inhibits ACHN cells via regulation of histone acetylation

“…Studies have shown that the degree of histone acetylation in renal cell carcinoma is low . The acetylation of histone H3 is diminished in the RCC 786-M-R cells (Wei et al 2018). The histone H3 in BNIP3 (bcl-2/adenovirus E1B 19 kDa interacting protein 3) promoter of both 786-O and ACHN is deacetylated, while the histone H3 in BNIP3 promoter of A498 is acetylated .…”

Single-cell RNA-seq identifies a reversible mesodermal activation in abnormally specified epithelia of p63 EEC syndrome

“…Heparin can bind to fibroblast growth factors (FGFs) and modulate their signaling pathways (34). VA is a histone deacetylase inhibitor that can up-regulate H3 acetylation and repress EMT (28). Although sumarin is well known for its antiviral and antiparasite effects (35), it was shown to inhibit mesodermal induction and formation in early Xenopus and sea urchin embryos (29,36).…”

“…As differentiated EEC-iPSCs had higher expression of immune response genes and a higher correlation with HSMM, we reasoned that these differentiated EEC-iPSCs exhibited an enhanced mesodermal identity, as both the immune system and skeletal muscles derive from the mesoderm. To directly assess whether the mesodermal activation is associated with the commitment defects of EEC-iPSCs and whether repressing mesodermal activation can enhance epidermal differentiation of EEC-iPSCs, we tested 3 inhibitors that can repress mesodermal induction, heparin, valproic acid (VA), and suramin (27)(28)(29).…”