Aberrant phosphorylation of human LRH1 at serine 510 is predictable of hepatocellular carcinoma recurrence.

We previously identified the AKT-phosphorylation sites in nuclear receptors and showed that phosphorylation of S379 in mouse retinoic acid γ and S518 in human estrogen receptor α regulate their activity independently of the ligands. Since this site is conserved at S510 in human liver receptor homolog 1 (hLRH1), we developed a monoclonal antibody (mAb) that recognized the phosphorylation form of hLRH1S510 (hLRH1 ^pS510 ) and verified its clinicopathological significance in hepatocellular carcinoma (HCC). We generated the anti-hLRH1 ^pS510 mAb and assessed its selectivity. We then evaluated the hLRH1 ^pS510 signals in 157 cases of HCC tissues by immunohistochemistry because LRH1 contributes to the pathogenesis of diverse cancers. The developed mAb specifically recognized hLRH1 ^pS510 and worked for immunohistochemistry of formalin-fixed paraffin-embedded tissues. hLRH1 ^pS510 was exclusively localized in the nucleus of HCC cells, but the signal intensity and positive rates varied among the subjects. According to the semi-quantification, 45 cases (34.9%) showed hLRH1 ^pS510 -high, and the remaining 112 cases (65.1%) exhibited hLRH1 ^pS510 -low. There were significant differences in the recurrence-free survival (RFS) between the two groups, and the 5-year RFS rates in the hLRH1 ^pS510 -high and hLRH1 ^pS510 -low groups were 26.5% and 46.1%, respectively. In addition, high hLRH1 ^pS510 was significantly correlated with portal vein invasion, hepatic vein invasion, and high levels of serum alpha-fetoprotein (AFP). Furthermore, multivariable analysis revealed that hLRH1 ^pS510 -high was an independent biomarker for HCC recurrence. We conclude that aberrant phosphorylation of hLRH1S510 is a predictor of poor prognosis for HCC. The anti-hLRH1 ^pS510 mAb could provide a powerful tool to validate the relevance of hLRH1 ^pS510 in pathological processes such as tumor development and progression.
(© 2023. The Author(s).)