In vitro studies of a prolactin antagonist, hPRL-G129R in human breast cancer cells.
Human prolactin (hPRL) has been shown to be one of the important survival/growth factors that promotes the proliferation of breast cancer cells in an autocrine/paracrine manner. In our recent studies, we demonstrated that a hPRL antagonist with a single amino acid substitution mutation (hPRL-G129R) was able to inhibit breast cancer cell proliferation via induction of apoptosis (1). In this study three independent yet related experiments were carried out regarding the effects of hPRL-G129R in breast cancer cells. We investigated the possible mechanism(s) of hPRL-G129R induced apoptosis in breast cancer cells. It is well documented that transforming growth factors (TGF) in conjunction with hormones such as estrogen and PRL play a major role in modulating the proliferation and apoptosis of mammary cells. We first investigated the relationships between hPRL/hPRL-G129R and TGFs. We show that hPRL is able to down-regulate TGF beta 1 (apoptotic factor) secretion and up-regulate TGF alpha (survival factor) secretion in a dose-dependent manner in T-47D cells. More importantly the hPRL antagonist up-regulates TGF beta 1 and down-regulates TGF alpha secretion. When hPRL-G129R was applied together with hPRL, it blocked the effects of hPRL. Secondly, we tested the possible involvement of caspases in hPRL-G129R induced apoptosis. We have shown that caspase-3 is activated by hPRL-G129R at a concentration of 250 ng/ml in T-47D breast cancer cells. Thirdly, we explored the additive effects of an anti-neoplastic drug, cisplatin, with the hPRL-G129R in T47D breast cancer cells. We show that cisplatin and hPRL-G129R when applied together resulted in about 40% growth inhibition in T-47D cells.
Ramamoorthy
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Department of Microbiology and Molecular Medicine, Clemson University, Clemson, SC 29681, USA.
Sticca
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R
Wagner
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Chen
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WY
D019943:Amino Acid Substitution; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001120:Arginine / Q000235:genetics; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004789:Enzyme Activation; D005260:Female; D005998:Glycine / Q000235:genetics; D006801:Humans; D017354:Point Mutation; D011388:Prolactin / Q000037:antagonists & inhibitors / Q000235:genetics / Q000494:pharmacology*; D016211:Transforming Growth Factor alpha / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism; D053773:Transforming Growth Factor beta1; D014407:Tumor Cells, Cultured
C508960:TGFB1 protein, human; D016211:Transforming Growth Factor alpha; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D011388:Prolactin; D001120:Arginine; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D002945:Cisplatin; D005998:Glycine