ERα inhibits the progression of hepatocellular carcinoma by regulating the circRNA/miRNA/SMADs network

Hepatocellular carcinoma (HCC) shows significant differences in incidence and mortality between genders.

This study investigates the mechanisms by which estrogen receptors (ER), specifically ERα, influence HCC outcomes.

Bioinformatics approaches were used to study estrogen and its related pathways in relation to HCC. Estrogen receptor expression levels, along with downstream circular RNAs (circRNAs) and microRNAs (miRNAs), were measured in MHCC97H cells via quantitative reverse transcription polymerase chain reaction (RT-qPCR). Western blot was used to assess estrogen receptor 1 (ESR1) and SMAD family member 7 (SMAD7) protein expression. Cell proliferation, migration and cell cycle status of MHCC97H cells were measured using Cell Counting Kit-8 (CCK-8), Transwell assays and flow cytometry for cell cycle analysis.

Bioinformatics analysis revealed that ERα acts as a transcription factor (TF) for 9 circRNAs with differential expression in HCC. We constructed the ERα/circRNA/miRNA/SMADs network based on the downstream targets of circRNAs, which were associated with the SMADs family. Survival studies revealed that ESR1 is correlated with favorable patient survival in liver cancer. In MHCC97H cells, qRT-PCR findings showed low expression of ESR1, hsa_circ_0004913 and SMAD7, but significant expression of hsa-miR-96-5p. Overexpression of ESR1 significantly increased the expression of hsa_circ_0004913 and SMAD7 while suppressing hsa-miR-96-5p. Western blot analysis confirmed these findings. Furthermore, ESR1 overexpression reduced MHCC97H cell proliferation and migration while inhibiting growth through G1 phase arrest. ESR1 acts as a TF that binds to the promoter of hsa_circ_0004913, as demonstrated using chromatin Immunoprecipitation followed by chromatin immunoprecipitation-quantitative real-time PCR (ChIP-qPCR). A dual-luciferase reporter experiment confirmed that hsa_circ_0004913 targets and regulates hsa-miR-96-5p.

ERα can function as aTF, modulating the expression of various circRNAs with differential expression in HCC. Through this regulation, it modulates the circRNA/miRNA/SMADs network, thereby inhibiting the progression of HCC.