Ramamoorthy P, Sticca R, Wagner T E, Chen W Y
Department of Microbiology and Molecular Medicine, Clemson University, Clemson, SC 29681, USA.
Int J Oncol. 2001 Jan;18(1):25-32. doi: 10.3892/ijo.18.1.25.
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.
人催乳素（hPRL）已被证明是重要的存活/生长因子之一，它以自分泌/旁分泌方式促进乳腺癌细胞的增殖。在我们最近的研究中，我们证明了一种具有单个氨基酸替代突变的hPRL拮抗剂（hPRL-G129R）能够通过诱导凋亡来抑制乳腺癌细胞增殖（1）。在本研究中，针对hPRL-G129R对乳腺癌细胞的作用进行了三个独立但相关的实验。我们研究了hPRL-G129R诱导乳腺癌细胞凋亡的可能机制。充分的文献记载表明，转化生长因子（TGF）与雌激素和PRL等激素共同作用，在调节乳腺细胞的增殖和凋亡中起主要作用。我们首先研究了hPRL/hPRL-G129R与TGF之间的关系。我们发现，hPRL能够在T-47D细胞中以剂量依赖的方式下调TGFβ1（凋亡因子）的分泌，并上调TGFα（存活因子）的分泌。更重要的是，hPRL拮抗剂上调TGFβ1并下调TGFα的分泌。当hPRL-Gl29R与hPRL一起应用时，它阻断了hPRL的作用。其次，我们测试了半胱天冬酶在hPRL-G129R诱导的凋亡中可能的参与情况。我们已经表明，在T-47D乳腺癌细胞中，浓度为250 ng/ml的hPRL-G129R可激活半胱天冬酶-3。第三，我们探讨了抗肿瘤药物顺铂与hPRL-G129R在T47D乳腺癌细胞中的相加作用。我们发现，顺铂和hPRL-G129R一起应用时，可导致T-47D细胞生长抑制约40%。
