BRCA1 promoter hypermethylation in human placenta: a hidden link with β-hCG expression

Carcinogenesis. 2020 Jul 10;41(5):611-624. doi: 10.1093/carcin/bgz117.

Abstract

Gestational trophoblastic diseases (GTD) are group of pregnancy-related tumors characterized by abnormal levels of 'β-hCG' with higher incidence in South-East Asia, especially India. Our laboratory has reported that wild-type BRCA1 transcriptionally regulates β-hCG in triple negative breast cancers (TNBCs). These factors culminated into analysis of BRCA1 status in GTD, which would emanate into elucidation of BRCA1- β-hCG relationship and unraveling etio-pathology of GTD. BRCA1 level in GTD is down-regulated due to the over-expression of DNMT3b and subsequent promoter hypermethylation, when compared to the normal placentae accompanied with its shift in localization. There is an inverse correlation of serum β-hCG levels with BRCA1 mRNA expression. The effects of methotrexate (MTX), which is the first-line chemotherapeutic used for GTD treatment, when analyzed in comparison with plumbagin (PB) revealed that PB alone is efficient than MTX alone or MTX-PB in combination, in showing selective cytotoxicity against GTD. Interestingly, PB increases BRCA1 levels post-treatment, altering DNMT3b levels and resultant BRCA1 promoter methylation. Also, cohort study analyzed the incidence of GTD at Sree Avittom Thirunal (SAT) Hospital, Thiruvananthapuram, which points out that 11.5% of gestational trophoblastic neoplasia (GTN) cases were referred to Regional Cancer Centre, Thiruvananthapuram, for examination of breast lumps. This has lend clues to supervene the risk of GTD patients towards BRCA1-associated diseases and unveil novel therapeutic for GTD, a plant-derived naphthoquinone, PB, already reported as selectively cytotoxic against BRCA1 defective tumors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antineoplastic Agents / pharmacology
  • Apoptosis
  • BRCA1 Protein / genetics*
  • BRCA2 Protein / genetics
  • Biomarkers, Tumor / genetics
  • Biomarkers, Tumor / metabolism
  • Cell Proliferation
  • Chorionic Gonadotropin, beta Subunit, Human / genetics
  • Chorionic Gonadotropin, beta Subunit, Human / metabolism*
  • Cohort Studies
  • DNA Methylation*
  • Female
  • Gene Expression Regulation, Neoplastic
  • Gestational Trophoblastic Disease / drug therapy
  • Gestational Trophoblastic Disease / genetics
  • Gestational Trophoblastic Disease / metabolism
  • Gestational Trophoblastic Disease / pathology*
  • Humans
  • Mutation*
  • Placenta / drug effects
  • Placenta / metabolism*
  • Placenta / pathology
  • Pregnancy
  • Pregnancy Complications / drug therapy
  • Pregnancy Complications / genetics
  • Pregnancy Complications / metabolism
  • Pregnancy Complications / pathology
  • Prognosis
  • Promoter Regions, Genetic*
  • Trophoblastic Neoplasms / drug therapy
  • Trophoblastic Neoplasms / genetics
  • Trophoblastic Neoplasms / metabolism
  • Trophoblastic Neoplasms / pathology
  • Tumor Cells, Cultured

Substances

  • Antineoplastic Agents
  • BRCA1 Protein
  • BRCA1 protein, human
  • BRCA2 Protein
  • BRCA2 protein, human
  • Biomarkers, Tumor
  • Chorionic Gonadotropin, beta Subunit, Human