苯并[a]芘通过PDX-1/TFAM通路诱导线粒体DNA损伤的机制研究OA

[Background]Previous studies have found that exposure to benzo[a]pyrene(BaP)can lead to functional impairment of the human pancreas.Pancreatic and duodenal homeobox factor 1(PDX-1)may play a role in regulating mitochondrial function.It is hypothesized that BaP exposure may interfere with PDX-1 expression in human pancreatic ductal epithelial cells(H6C7),thereby affecting mitochondrial transcription factor A(TFAM).This process could induce mitochondrial DNA(mtDNA)damage,disrupt pancreatic development and function,and elevate the risk of dia-betes onset. [Objective]To investigate the mechanism of BaP-induced mtDNA damage through disruption of the PDX-1/TFAM pathway in a H6C7 cell model. [Methods]A H6C7 cell injury model was established using different concentrations of BaP.Cell viability was determined using cell counting kit-8(CCK-8).After 24 h of BaP exposure(5,10,and 20 μmol·L-1),cell morphological and mitochondrial membrane potential(MMP)changes were observed via confocalmicroscopy,and PDX-1/TFAM protein expression levels were assessed.Bioinformatics analysis com-bined with dual-luciferase reporter assays was used to confirm PDX-1 directly targeting the TFAM promoter.Following PDX-1 overexpres-sion or silencing in BaP treated cells,flow cytometry was used to evaluate viability and apoptosis,while Western blot and quantitative re-al-time reverse transcription polymerase chain reaction(qRT-PCR)measured PDX-1/TFAM expression and mitochondrial DNA copy number(mtDNA-cn). [Results]The cell injury model demonstrated that,compared with the control group,BaP exposure reduced cell viability,disrupted membrane integrity,induced nuclear fragmentation,and decreased MMP.Protein expression levels of PDX-1 and TFAM were significantly downregulated in the 10 and 20 μmol·L-1 groups(P<0.05).Dual-luciferase reporter assays confirmed that PDX-1 overexpression upregulated TFAM levels.Flow cytometry revealed that PDX-1 overexpression significantly reduced apoptosis rate(P<0.001),whereas PDX-1 silencing increased apoptosis rate(P<0.001).Compared with the BaP-only group,BaP+PDX-1 overexpression elevated TFAM protein and mRNA ex-pression as well as mtDNA-cn(P<0.01),while BaP+siRNA-PDX-1 suppressed these parameters(P<0.001). [Conclusion]BaP exposure promotes apoptosis in human pancreatic cells.PDX-1,a key gene in pancreatic development,regulates the expression of TFAM,a core regulator of mitochondrial function.This interaction triggers changes in MMP and mtDNA-cn,activates the PDX-1/TFAM/mtDNA axis,and ultimately leads to pancreatic cell injury.