To gain insight into the molecular mechanisms involved in human prolactin receptor antagonist (hPRL-G129R)-induced apoptosis, we used real-time reverse transcription-polymerase chain reaction to measure bax and bcl-2 gene expression in 11 human breast cancer cell lines following treatment with hPRL and hPRL-G129R. We also measured bax and bcl-2 gene expression in the mammary glands of transgenic mice expressing hPRL or hPRL-G129R. A time-course study of hPRL and antagonist treatment in T-47D cells indicated changing bax/bcl-2 mRNA ratios beginning at 24 h. We found that bax/bcl-2 mRNA ratios were significantly elevated in seven of the 11 hPRL-G129R-treated cell lines, as well as in the hPRL-G129R transgenic mice. To confirm these results, Bax and Bcl-2 proteins were analysed by Western blot methods in mammary gland tissue homogenates of transgenic mice. Bax/Bcl-2 ratios were highest in the 6-month group of hPRL-G129R transgenics, and lowest in the 6-month group of hPRL transgenics. We expanded our findings by examining the release of a downstream Bax-induced protein, cytochrome c, a hallmark protein of apoptosis, in transgenic mice. Again, cytochrome c levels were highest in the 6-month hPRL-G129R transgenic group. Thus, hPRL-G129R-induced breast cancer cell and/or mammary gland apoptosis is mediated, at least in part, through the regulation of Bax and Bcl-2 gene expression.

1999-11-01·Clinical cancer research : an official journal of the American Association for Cancer Research

A human prolactin antagonist, hPRL-G129R, inhibits breast cancer cell proliferation through induction of apoptosis.

Article

作者: Chen, N ; Ramamoorthy, P ; Sticca, R ; Chen, W Y ; Wagner, T E

Human breast cancer is the predominant malignancy and the leading cause of cancer death in women from Western societies. The cause of breast cancer is still unknown. Recently, the association between human prolactin (hPRL) activity and breast cancer has been reemphasized. Biologically active hPRL has been found to be produced locally by breast cancer cells that contain high levels of PRL receptor. A high incidence of mammary tumor growth has also been found in transgenic mice overexpressing lactogenic hormones. More importantly, it has been demonstrated that the receptors for sex steroids and PRL are coexpressed and cross-regulated. In this study, we report that we have designed and produced a hPRL antagonist, hPRL-G129R. By using cell proliferation assays, we have demonstrated that: (a) hPRL and E2 exhibited an additive stimulatory effect on human breast cancer cell (T-47D) proliferation; (b) hPRL-G129R possessed an inhibitory effect on T-47D cell proliferation; and (c) when antiestrogen (4-OH-tamoxifen) and anti-PRL (hPRL-G129R) agents were added together, an additive inhibitory effect was observed. We further investigated the mechanism of the inhibitory effects of hPRL-G129R in four hPRLR positive breast cancer cell lines. We report that hPRL-G129R is able to induce apoptosis in all four cell lines in a dose-dependent manner as determined by the Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. The apoptosis is induced within 2 h of treatment at a dose as low as 50 ng/ml. We hope that the hPRL antagonist could be used to improve the outcome of human breast cancer therapy in the near future.

International Journal of Oncology2区 · 医学

In vivo studies of the anti-tumor effects of a human prolactin antagonist, hPRL-G129R

2区 · 医学

Article

作者: Peirce, S. K. ; Li, W. ; Chen, W. Y. ; Chen, N. Y. ; Holle, L. ; Beck, M. T.

Previously we demonstrated that a mutated human prolactin (hPRL) with a single amino acid substitution at position 129 (hPRL-G129R) was able to inhibit human breast cancer cell proliferation via the induction of apoptosis. In this study, we report the in vivo anti-tumor effects of hPRL-G129R in nude mice bearing human breast cancer xenografts (T-47D and MCF-7). In an effort to prolong the half-life of the proteins, hPRL or hPRL-G129R were formulated with either growth factor reduced Matrigel or into slow-releasing pellets (custom made 5 mg/5 day release). Initially, nude mice inoculated (s.c.) with T-47D human breast cancer cells were treated with either hPRL or hPRL-G129R formulated with Matrigel. At the end of the 7-week study, it was found that hPRL significantly stimulated the in vivo growth of T-47D xenografts (mean tumor volume, 202 +/- 62 mm(3) as compared to 124 +/- 31 mm(3) in control mice), whereas hPRL-G129R inhibited the tumor growth (mean tumor volume, 79+/-32 mm3). The inhibitory effects of hPRL-G129R were further confirmed in a second experiment using nude mice bearing MCF-7 human breast cancer xenografts and treated with slow-releasing pellets containing hPRL-G129R. Based on these results, we believe that hPRL-G129R can be used to improve the outcome of human breast cancer treatment in the near future.

100 项与 hPRL-G129R 相关的药物交易

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