Estrogens play a crucial role in the genesis of the majority of breast cancers, promoting the survival, proliferation and invasiveness of tumor cells. These hormones act by binding to their receptors, which fall into two groups, ER and GPER, whose properties differ.
The team of Didier Picard, professor at the Department of Cell Biology of the Faculty of Sciences of UNIGE, is interested in GPER receptors, whose effects on breast cancer are less well known than those of the ER family. “By analyzing a breast tumor biopsy, our colleagues at the University of Calabria, who participated in this study, discovered GPER receptors in the nucleus of fibroblasts present around the malignant cells, whereas they had always been localized elsewhere before,” says the biologist.
Fibroblasts abound around the tumor
Fibroblasts, constituents of the connective tissue, are part of the microenvironment of the tumors. “Knowing that cancer cells interact with neighboring healthy cells to survive and grow, we wanted to find out whether the GPER receptors observed in the nucleus of these fibroblasts were involved in this process,” explains Marco Pupo, first author of the study.
The researchers have discovered the existence of another version of GPER: “This genetic variant results from a tiny change, a single nucleotide, in the gene that codes for the GPER receptor. This is sufficient to induce its relocation to the nucleus. We detected the presence of this same version of the gene in the fibroblasts of the eight other biopsies we analyzed, from the University Hospital of Geneva,” states Didier Picard.