Increased Expression of Prolactin Receptor Gene Assessed by Quantitative Polymerase Chain Reaction in Human Breast Tumors Versus Normal Breast Tissues

The role of PRL in human breast tumorigenesis is not well understood. One of the limitations is the difficulty of accurately measuring PRL receptors (PRLR) in human tissues. We established a quantitative PCR method (Q-PCR) in T-47D human breast cancer cells and applied it to 29 patients, 25 of whom presented with either cancer or fibroadenoma. Four patients underwent a mammoplasty, and normal epithelial cells were cultured before Q-PCR. In T-47D cells, 31 × 106 messenger RNA molecules were detected per microgram of total RNA. In all patients, expression of the PRLR gene was detected, varying from 1500 to 1 × 106 molecules/μg of RNA in normal tissues and from 4500 to 34.7 × 106 molecules/μg of RNA in tumors. PRLR expression was always greater in tumor than in normal contiguous tissue and similar in cultured mammary epithelial cells and normal breast tissues. Estradiol and progesterone receptor-negative tumors expressed low levels of PRLR transcripts, similar to normal breast tissue from menopausal women. I...