title: Novel roles of prolactin and estrogens in breast cancer: resistance to chemotherapy.
abstract: Resistance to chemotherapy is a major complication in the treatment of advanced breast cancer. Estrogens and prolactin (PRL) are implicated in the pathogenesis of breast cancer but their roles in chemoresistance have been overlooked. A common feature to the two hormones is activation of their receptors by diverse compounds, which mimic or antagonize their actions. The PRL receptor is activated by lactogens (PRL, GH, or placental lactogen) originating from the pituitary, breast, adipose tissue, or the placenta. Estrogen receptors exist in multiple membrane-associated and cytoplasmic forms that can be activated by endogenous estrogens, man-made chemicals, and phytoestrogens. Here, we review evidence that low doses of PRL, estradiol (E(2)), and bisphenol A (BPA) antagonize multiple anticancer drugs that induce cell death by different mechanisms. Focusing on cisplatin, a DNA-damaging drug which is effective in the treatment of many cancer types but not breast cancer, we compare the abilities of PRL, E(2), and BPA to antagonize its cytotoxicity. Whereas PRL acts by activating the glutathione-S-transferase detoxification enzyme, E(2) and BPA act by inducing the antiapoptotic protein Bcl-2. The implications of these findings to patients undergoing chemotherapy are discussed.
authors.affiliation: Department of Cancer and Cell Biology, University of Cincinnati, Ohio 45267-0521, USA.
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: LaPensee
authors.forename: Nira
authors.initials: N
authors.lastname: Ben-Jonathan
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D001559:Benzhydryl Compounds; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm; D004958:Estradiol / Q000378:metabolism* / Q000494:pharmacology; D005260:Female; D019254:Genes, bcl-2 / Q000187:drug effects; D005982:Glutathione Transferase / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D010636:Phenols / Q000494:pharmacology / Q000627:therapeutic use; D011388:Prolactin / Q000378:metabolism* / Q000494:pharmacology; D011960:Receptors, Estrogen / Q000378:metabolism; D011981:Receptors, Prolactin / Q000378:metabolism; D000098826:Bisphenol A Compounds
chemical_list: D000970:Antineoplastic Agents; D001559:Benzhydryl Compounds; D002945:Cisplatin; D004958:Estradiol; D005982:Glutathione Transferase; D010636:Phenols; D011388:Prolactin; D011960:Receptors, Estrogen; D011981:Receptors, Prolactin; C006780:bisphenol A; D000098826:Bisphenol A Compounds