The Endocrine Approach of Melanoma: The Puzzle of Estrogen Receptors Expression

Melanoma outcome seems different between females and males, with a potential protective role of estrogen (E) through estrogen receptors (ER) expression into the tumor. In the study of ERs, both alfa (ERα) and beta (ERβ) is a well-known endocrine elements in non-melanoma tumors, like mammary and endometrial cancer. Immunohistochemistry (IHC) assessment of melanoma concerning ERs represents a path to explore the tumor profile to provide useful information concerning the prognostic and potential adjuvant treatment. Currently, this is not a routine practice, nor a mandatory step for deciding the medical therapy. Typically, IHCs are based on usual kits for mammary tumors regarding ERs configuration. Prior/concomitant use of oral contraceptives and hormonal replacement therapy is not correlated with a better prognostic in melanoma; neither have they represented a contraindication for survivors of melanoma; a subset of tumors might present a higher ER expression which is potentially targeted by the hormone-based treatment as SERMs (Selective Estrogen Receptors Modulator), for instance, tamoxifen. Experimental studies on melanoma cell lines confirmed the anti-tumor activity of ERβ which might function as a prognostic marker. G-protein-coupled estrogen receptors in melanocytes and keratinocytes might be involved, too. Additional crosstalk of TGF-β (Transforming Growth Factor β), respective IGF1 (Insulin-like Growth Factor), and ERα expression are involved in tumorigenic pathways. Recent preclinical studies showed the potential benefits of diarylpropionitrile, a selective agonist of ERβ; pyrazole derivates 21-23 can block ERs. Murine melanoma models showed the interference of anti-estrogenic medication (like molecule fulvestrant) to enhance immune checkpoint blockade, a modern approach to solid cancers. The proliferation of melanoma might be partially explained by ERs; whether this is generally applicable or there is a subgroup of tumors particularly related to E status is still debatable. The subject of E status in melanoma is far from clear at this point and further studies are necessary concerning this particular issue to implement it as a practical approach in the daily management of a disease that still has a very severe prognostic nowadays.