The HMGA2/MPC1 Axis Plays An Important Role In Cr(Ⅵ)-induced Glycolysis And Lung Cancer Proliferation

Objective: Hexavalent chromium [Cr(VI)] poses a significant environmental hazard due to its toxicity,solubility and mobility,and is a Class I carcinogen identified by IARC,however,its carcinogenesis is unclear.Previous studies have shown that potassium dichromate induces glycolysis by activating endoplasmic reticulum stress.Mitochondrial pyruvate carrier 1(MPC1),a structure that controls the entry of pyruvate from cytoplasm to mitochondria,plays an important role in glycolysis and oxidative phosphorylation and is involved in many diseases,such as cancer and metabolic diseases.Numerous studies have shown low expression of MPC1 in colorectal,esophageal,and lung cancers,but the mechanism is unclear.In our previous study,we found that in lung adenocarcinoma cells,the highly migratory group A2(HMGA2)plays an important role in the metabolic reprogramming of potassium dichromate from oxidative phosphorylation to glycolysis by accumulating in mitochondria and binding directly to the D-loop region of mt DNA.At present,no specific mechanism of action of potassium dichromate on MPC1 has been reported,and the specific regulatory mechanism of MPC1 is under exploration.Therefore,we investigated the role of HMGA2 and MPC1 in Cr(VI)-induced glycolysis by targeting low doses in A594,HELF and BALB/c lung tissue.Methods: We used human embryonic pulmonary fibroblasts(HELF cells)and adenocarcinoma human alveolar basal epithelial cells(A549 cells)as in vitro models and BALB/c mice as in vivo models.MPC1 protein expression in BALB/c mice was measured at 0,6,12,24 hours of treatment with potassium dichromate at 0.2μM concentration,and MPC1 protein expression in lung tissue of BALB/c mice was observed by protein imprinting.Wound healing assays were performed to observe changes in cell proliferation and migration induced by potassium dichromate treatment with transfected plasmid MPC1.The effect of transfected plasmid MPC1 on apoptosis was observed by Hochest 33258 staining.The expression of glycolysis-related proteins induced by potassium dichromate was significantly reduced after plasmid transfection and expression of MPC1.HMGA2 expression was downregulated in A549 cells using small interfering RNA,and si HMGA2 treatment restored expression of MPC1 inhibited by potassium dichromate.HMGA2 binding to the promoter of the MPC1 gene was observed using the Ch IP assay.The expression of glycolysis-related proteins following transfection of HMGA2 / transfected plasmid MPC1 was determined by Western blots.Western blots were performed to detect changes in MPC1 inhibition following pretreatment with the endoplasmic reticulum stress inhibitor 4-phenylbutyric acid(4PBA).Secondly,the effect of endoplasmic reticulum stress on MPC1 was observed using Tunicamycin(Tm)as an endoplasmic reticulum stress activator.We established a xenograft model in BALB / c mice to observe the effect of MPC1 on xenograft formation.Results: Intracellular MPC1 expression was significantly reduced in A549 and HELF cells treated with 0.2μM for 0,6,12,24 hours and in lung tissue of BALB / c mice treated with potassium dichromate.Wound healing and Hochest 33258 staining assays showed that plasmid transfection and expression of MPC1 inhibited A549 cell growth and migration induced by potassium dichromate.The expression of glycolysis-related proteins induced by potassium dichromate was significantly reduced after plasmid transfection and expression of MPC1.HMGA2 expression was downregulated in A549 cells using small interfering RNA,and si HMGA2 treatment restored expression of MPC1 inhibited by potassium dichromate Ch IP assays showed that HMGA2 binds to the promoter of the MPC1 gene.HMGA2 induced significantly reduced glycolysis-related protein expression and inhibited cell proliferation and migration after transfection with plasmid MPC1.After inhibition of endoplasmic reticulum stress with4 PBA,MPC1 expression was upregulated by potassium dichromate inhibition.Treatment of A549 cells with different concentrations of the endoplasmic reticulum stress inducer Tm(0.1μg/ml and 2μg/ml)inhibited the expression of MPC1 in A549 cells.In xenograft tumor assays,subcutaneous injection of transfected plasmid MPC1-treated A549 cells significantly inhibited the weight and volume of BALB/c mouse xenografts.Conclusion: MPC1 expression is inhibited by potassium dichromate through endoplasmic reticulum stress(ER)and HMGA2 in A594,HELF and BALB/c lung tissue.The main molecular mechanism is HMGA2 transcriptional regulation of MPC1 induced by ER stress,while MPC1 plays a significant role in inhibition of glycolysis and cell proliferation.