LONP1 Promotes Hepatocarcinogenesis by Degrading ACO2 to Alleviate Ferroptosis.

Background: Lon protease 1 (LONP1), an adenosine triphosphate (ATP)-dependent protease encoded by nuclear DNA that is highly conserved, maintains the mitochondrial protein balance and regulates adaptive responses to cellular stress. LONP1 dysfunction ultimately results in various forms of cellular and tissue damage. The function of LONP1 in hepatocellular carcinoma (HCC) and how it affects HCC growth were investigated in this work.

Methods: The RNA and protein expression levels of LONP1 were determined in paired HCC and adjacent tissue samples through real-time quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry (IHC) staining. The correlation between LONP1 expression and clinical features was evaluated via statistical analysis. Overexpression (OE) and knockdown (KD) experiments, small RNA interference, Cell Counting Kit-8 (CCK8) and wound-healing assays, and animal experiments were employed to assess the potential mechanism by which LONP1 promotes the proliferation and migration of HCC cells both in vitro and in vivo.

Results: In HCC samples, LONP1 expression was higher than in the equivalent surrounding tissues. Compared to patients with low LONP1 expression, individuals with high LONP1 expression had shorter disease-free survival and overall survival periods. Functionally, LONP1 facilitated the proliferation and migration of HCC cells, whereas LONP1 knockdown mitigated the growth of HCC subcutaneous tumors. Mechanistically, LONP1 affects the processes of ferroptosis and cuproptosis processes by regulating the stability of aconitase 2 (ACO2). Histological analysis showed that the expression of LONP1 in liver cancer tissues was significantly upregulated, accompanied by a decrease in the level of ACO2 protein (Hematoxylin-Eosin (HE) staining and IHC verification). Mitochondrial function experiments indicated that overexpression of LONP1 led to a significant decrease in mitochondrial membrane potential suggesting mitochondrial dysfunction and reduced susceptibility to ferroptosis.

Conclusions: Our results suggest that LONP1 promotes HCC proliferation and migration by inhibiting ferroptosis and cuproptosis through the degradation of ACO2. Therefore, targeting LONP1 might be an effective therapeutic strategy to inhibit HCC growth.