Prolonged recombinant pregnancy hormone use in BRCA1 and BRCA2 mutation carriers

Treatment of women with BRCA mutation

The cumulative risk for breast and ovarian cancer is high in BRCA1 or BRCA2 mutation carriers. The lifetime risk of breast cancer by the age of 80 years is respectively up to 72% and 69% in BRCA1 and BRCA2 mutation carriers. The risk of ovarian cancer is higher (44%) in BRCA1 than in BRCA2 (17%) mutation carriers. Breast and ovarian cancers tend to arise earlier in BRCA1 mutation carriers. Breast cancers in BRCA1 mutation carriers are more frequently (up to 70%) triple negative while the majority (up to 80%) of breast cancers in BRCA2 mutation carriers are hormone sensitive. Many issues remain to be resolved. In daily practice we are often confronted with patients having BRCA mutations classified as variants of unknown significance, who do have breast cancer personally or have a strong family history of breast cancer. On the other hand, 30-40% of mutation carriers will not develop breast cancer. Moreover, it is very difficult to predict the age at which cancer will arise. In a multidisciplinary setting we need to offer BRCA and other mutation carriers a wide range of information, advice and support.

Recombinant human chorionic gonadotropin induces signaling pathways towards cancer prevention in the breast of BRCA1/2 mutation carriers

BACKGROUND

Strategies for breast cancer prevention in women with germline BRCA1/2 mutations are limited. We previously showed that recombinant human chorionic gonadotropin (r-hCG) induces mammary gland differentiation and inhibits mammary tumorigenesis in rats. The present study investigated hCG-induced signaling pathways in the breast of young nulliparous women carrying germline BRCA1/2 mutations.

METHODS

We performed RNA-sequencing on breast tissues from 25 BRCA1/2 mutation carriers who received r-hCG treatment for 3 months in a phase II clinical trial, we analyzed the biological processes, reactome pathways, canonical pathways, and upstream regulators associated with genes differentially expressed after r-hCG treatment, and validated genes of interest.

RESULTS

We observed that r-hCG induces remarkable transcriptomic changes in the breast of BRCA1/2 carriers, especially in genes related to cell development, cell differentiation, cell cycle, apoptosis, DNA repair, chromatin remodeling, and G protein-coupled receptor signaling. We revealed that r-hCG inhibits Wnt/β-catenin signaling, MYC, HMGA1 , and HOTAIR , whereas activates TGFB/TGFBR-SMAD2/3/4, BRCA1, TP53, and upregulates BRCA1 protein.

CONCLUSION

Our data suggest that the use of r-hCG at young age may reduce the risk of breast cancer in BRCA1/2 carriers by inhibiting pathways associated with stem/progenitor cell maintenance and neoplastic transformation, whereas activating genes crucial for breast epithelial differentiation and lineage commitment, and DNA repair.