PT Unknown
AU Hamidi, A
TI Enhancing Radiosensitivity of Murine Hepatocytes in Hypoxia through HIF-1α Depletion
PD 10
PY 2023
DI 10.17185/duepublico/79146
LA en
DE hypoxia; HIF-1α; ionizing radiation; DNA damage repair
AB Hepatocellular Carcinoma (HCC) is a prevalent cancer affecting a significant number of individuals worldwide. Enhancing the efficacy of radiotherapy, a treatment modality for HCC which is under development, holds great potential for improving patient outcomes. In this study, we established cultured murine hepatocyte derived cells (mHDC) as an in vitro model and aimed to elucidate the impact of Hypoxia-inducible Factor 1 alpha (HIF-1α) on DNA damage repair, radiation sensitivity, and cellular metabolism in murine hepatocyte-derived cells (mHDC). To better understand the role of HIF-1α, we developed an in vitro model using murine hepatocyte-derived cells (mHDC) that bear a complete knockout for HIF-1α. We assessed the impact of HIF-1α deficiency on DNA damage repair following ionizing radiation (IR) exposure under hypoxic conditions. Our findings revealed that HIF-1α deficiency increased IR-induced apoptosis and significantly reduced the surviving fraction of mHDC as compared to HIF-1α expressing cells in colony formation assays. Moreover, HIF-1α-depleted cells exhibited increased accumulation of IR-induced DNA damage, as evidenced by upregulated γH2AX foci. Furthermore, HIF-1α-deficient cells displayed delayed DNA repair after IR treatment in hypoxia, suggesting a potential effect on non-homologous end joining (NHEJ) repair capacity, as observed in neutral comet assays. Notably, there were no significant differences in reactive oxygen species (ROS) levels among the treatment groups, suggesting that the effects caused by HIF-1α deficiency are unlikely to be mediated by ROS. To further investigate the relationship between HIF-1α and cellular metabolism, we analyzed the respiratory metabolism and mitochondrial morphological changes in HIF-1α knockout cells. Interestingly, HIF-1α-deficient cells exhibited a significant increase in the oxygen consumption rate (OCR) and a reduction in the extracellular acidification rate (ECAR) compared to wildtype cells. Additionally, we observed alterations in mitochondrial morphology, with a decrease in the number of mitochondria following hypoxia, but an increase in knockout cells compared to wildtype cells. Collectively, our results suggest that HIF-1α inactivation enhances radiation sensitivity in mHDC cells, accompanied by an elevation in OCR and reduced glycolysis. These findings contribute to a better understanding of the molecular mechanisms underlying radioresistance and metabolic changes in mHDC.
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