Role of Mammary Prolactin in Carcinogenesis
Annual rept. 15 Sep 1994-14 Sep 1995
CINCINNATI UNIV OH
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Prolactin Prl is a mitogenic hormone that shares characteristics with growth factors. Recent reports that rat mammary tissue expresses PRL mRNA led us to hypothesize that PRL acts as an autocrineparacrine growth factor in the mammary gland, and may be a determinant in mammary carcinogenesis. To examine this, mammary tumors were induced in rats by injecting the carcinogen nitrosomethylurea NMU. In vitro studies utilized an NMU-derived mammary tumor cell line. The mammary tumors and the cell line express niRNA for both PRL and PRL receptor, as assessed by reverse transcriptase RT-PCR. Immunoreactive PRL was detected in the NMU-induced tumors. NMU cells were cultured with PRL antiserum. The PRL antiserum inhibited cell proliferation 40-50 as compared to normal rabbit serum NRS or GM antiserum. In summary, we have shown that NMU-induced mammary tumors express rnRNA for PRL and PRL receptor. The addition of PRL antiserum to cultured NMU cells inhibited their growth. We propose that PRL may be acting as a local growth factor that stimulates proliferation of mammary tumors.
- Medicine and Medical Research
- Anatomy and Physiology