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 diabetes 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 combined with dual-luciferase reporter assays was used to confirm PDX-1 directly targeting the TFAM promoter. Following PDX-1 overexpression or silencing in BaP treated cells, flow cytometry was used to evaluate viability and apoptosis, while Western blot and quantitative real-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 expression 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.

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 diabetes 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 combined with dual-luciferase reporter assays was used to confirm PDX-1 directly targeting the TFAM promoter. Following PDX-1 overexpression or silencing in BaP treated cells, flow cytometry was used to evaluate viability and apoptosis, while Western blot and quantitative real-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 expression 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.