HIF1α Contribution to the NHEJ DNA Repair Pathway Through Decreased Expression of XRCC4

Abstract

Background: Hypoxia-inducible factor 1α (HIF1α), a key transcription factor activated during low oxygen levels, influences cell cycle and metastasis. Hypoxia induces double-strand breaks (DSBs), a highly carcinogenic process. Objectives: This study aimed to elucidate the impact of HIF1α down-regulation on the expression of XRCC4 and XRCC7, key components of the non-homologous end joining (NHEJ) pathway crucial for DSB repair. Methods: HeLa and [human embryonic kidney (HEK)293] cells underwent culture, transfection with HIF1α small interfering ribonucleic acid (siRNA), and viability assessment after 48 hours. Subsequent examination included cell cycle alterations. Ribonucleic acid extraction, complementary deoxyribonucleic acid (cDNA) synthesis, and RT-qPCR were performed to compare the fold-change in HIF1α, XRCC4, and XRCC7 gene expression, followed by statistical analyses. Results: Downregulating HIF1α using siRNA resulted in reduced viability and increased apoptosis in both HeLa and HEK293 cells 48 hours after transfection. The findings also indicated a significant decrease in XRCC4 expression; nevertheless, XRCC7 expression remained unchanged in both cell lines. Conclusions: This study underscores that HIF1α potentially modulates the NHEJ pathway through XRCC4, presenting itself as a plausible target for cancer therapy.