AURORA KINASE A IN CHRONIC LIVER DISEASE AND HEPATOCELLULAR CARCINOMA: DISTINCT MECHANISMS AND ROLES

This study investigated the potentially distinct role of Aurora Kinase A (AURKA) in chronic liver disease (CLD) and hepatocellular carcinoma (HCC), revealing context-dependent regulatory mechanisms that remain poorly investigated in CLD and HCC contexts. Analyses of 56 paired HCC samples revealed a striking mRNA-protein discordance. While AURKA mRNA was significantly elevated in tumors, AURKA protein demonstrated the opposite pattern, with marked upregulation in the adjacent, non-tumoral tissues. Immunohistochemical (IHC) validation confirmed the overexpression of AURKA with predominantly hepatocytic expression within the chronically injured liver tissues across various etiologies. Notably, phospho-AURKA (Thr288), the activated form of the enzyme associated with cell cycle control, was elevated in 61% of the tumors, suggesting that enhanced regulatory activity of the cell cycle, rather than the total expression, is linked to neoplastic transformation. In the adjacent tissues, AURKA protein levels significantly correlated with the expression of Yes-associated protein 1 (YAP1), while no correlation was found in HCC. YAP1 protein was also significantly increased in both adjacent and metabolic dysfunction-associated steatotic liver tissue samples. Functional validation through AURKA silencing in JHH6 cells demonstrated a marked reduction in total YAP1 protein with minimal effect on phospho-YAP1 (Ser397), suggesting AURKA modulates YAP1 stability rather than phosphorylation-dependent activation, potentially affecting liver regeneration, DNA damage response and apoptosis. AURKA has emerged as a positive regulator of PD-L1 expression in HCC cells. Both pharmacological inhibition (AK-01) and knockdown (siRNA) consistently reduced PD-L1 protein levels in HCC cells. With distinction, while silencing primarily affects newly synthesized PD-L1, AK-01 reduces the stability of PD-L1 inducing a proteasome-dependent degradation. Different cell lines exhibit varying PD-L1 stability: JHH6 cells showed the longest PD-L1 half-life, while HLE and Hep3B demonstrated the shortest, which was also associated with very low PD-L1 levels. Contrary to what has been reported in literature, PD-L1 proteasomal degradation appears to be GSK-3β independent. Neither AURKA inhibition nor knockdown altered p-GSK-3β (Ser9) levels. Furthermore, GSK-3β knockdown failed to recapitulate PD-L1 accumulation, suggesting cell-specific effects rather than the predicted GSK-3β-mediated PD-L1 reduction. Comparative gene expression profiling revealed that AURKA and GSK-3β operate through largely independent regulatory networks. In JHH6 cells, AURKA knockdown downregulated proliferation markers (CTNNB1, AXIN2) and glycolytic genes (GLUT1, PKM2), while in HuH7 cells, AURKA demonstrated broader control over metabolism, fibrosis, and inflammatory pathways. GSK-3β showed a more focus, cell-specific effects. Notably, CDKN1A emerged as a convergent target, with its expression positively regulated by both AURKA and GSK-3β, as evidenced by consistent downregulation following knockdown of either kinase across cell lines. These findings establish AURKA as a context-dependent regulator with distinct functions in CLD and HCC. In chronically injured liver, AURKA-YAP1 signaling may coordinate tissue repair responses, while in established tumors, AURKA promotes immune evasion through PD-L1 stablization. The correlation between AURKA and YAP1 in adjacent tissues further suggests potential biomarker utility for CLD progression, while AURKA’s role in PD-L1 regulation positions it as a compelling target for combination immunotherapy strategies in HCC. This work fundamentally reframes AURKA from a simple oncogenic driver to a key hub in a complex network of signaling pathways whose functions adapt to pathophysiological context, offering new therapeutic opportunities across the liver disease spectrum.