Dihydrotanshinone I targets ESR1 to induce DNA double-strand breaks and proliferation inhibition in hepatocellular carcinoma

Background: Due to its high incidence and elevated mortality, hepatocellular carcinoma (HCC) has emerged as a formidable global healthcare challenge. The intricate interplay between gender-specific disparities in both incidence and clinical outcomes has prompted a progressive recognition of the substantial influence exerted by estrogen and its corresponding receptors (ERs) upon HCC pathogenesis. Estrogen replacement therapy (ERT) emerged for the treatment of HCC by administering exogenous estrogen. However, the powerful side effects of estrogen, including the promotion of breast Cancer and infertility, hinder the further application of ERT. Identifying effective therapeutic targets for estrogen and screening bioactive ingredients without E2-like side effects is of great significance for optimizing HCC ERT.

Methods: In this study, we employed an integrative approach, harnessing data from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, clinical paraffin sections, adenoviral constructs as well as in vivo studies, to unveil the association between estrogen, Estrogen Receptor α (ESR1) and HCC. Leveraging methodologies encompassing molecular dynamics simulation and cellular thermal shift assay (CETSA) were used to confirm whether ESR1 is a molecular target of DHT. Multiple in vitro and in vivo experiments were used to identify whether i) ESR1 is a crucial gene that promotes DNA double-strand breaks (DSBs) and proliferation inhibition in HCC, ii) Dihydrotanshinone I (DHT), a quinonoid monomeric constituent derived from Salvia miltiorrhiza (Dan shen) exerts anti-HCC effects by regulating ESR1 and subsequent DSBs, iii) DHT has the potential to replace E2.

Results: DHT could target ESR1 and upregulate its expression in a concentration-dependent manner. This, in turn, leads to the downregulation of breast Cancer type 1 susceptibility protein (BRCA1), a pivotal protein involved in the homologous recombination repair (HRR) process. The consequence of this downregulation is manifested through the induction of DSBs in HCC, subsequently precipitating a cascade of downstream events, including Apoptosis and cell cycle arrest. Of particular significance is the comparative assessment of DHT and isodose estradiol treatments, which underscores DHT's excellent HCC-suppressive efficacy without concomitant perturbation of endogenous sex hormone homeostasis.

Conclusion: Our findings not only confirm ESR1 as a therapeutic target in HCC management but also underscores DHT's role in upregulating ESR1 expression, thereby impeding the proliferation and invasive tendencies of HCC. In addition, we preliminarily identified DHT has the potential to emerge as an agent in optimizing HCC ERT through the substitution of E2.

DNA double-strand breaks; Dihydrotanshinone I; Estrogen receptor α; Estrogen replacement therapy; Gender difference; Hepatocellular carcinoma.