Expression of prolactin receptor mRNA in oestrogen receptor positive breast cancers pre- and post-tamoxifen therapy.
OBJECTIVE
Previous in vitro studies have shown that tamoxifen down-regulates prolactin receptors in breast cancer cells. The aim of this study was to determine whether similar changes might provide the basis for a predictive test in patients.


METHODS
Biopsy specimens were obtained from 28 post-menopausal women immediately before initiation of treatment with tamoxifen (20 mg daily) and after treatment for 7 days. Prolactin receptor mRNA, determined by reverse-transcription polymerase chain reaction, was then expressed relative to 18S ribosomal RNA.


RESULTS
There was good evidence for a decline in receptor expression in response to treatment with tamoxifen in the whole group (p = 0.036) but with a particularly marked decrease (>60%) in a sub-group of 11 patients. No clear correlation with tumour type or grade, or with several other markers (progesterone receptor, c-erb B-2, pS2, or Bcl-2) was apparent.


CONCLUSIONS
Tamoxifen reduces expression of mRNA encoding the prolactin receptor in a sub-group of breast tumours and might provide the basis for a predictive test for tamoxifen therapy.
de Castillo
B
B
Breast Care Centre, North Bristol NHS Trust, Bristol BS16 1LE, UK.
Cawthorn
S
S
Moppett
J
J
Shere
M
M
Norman
M
M
D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000096:biosynthesis; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009367:Neoplasm Staging; D017698:Postmenopause / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012334:RNA, Neoplasm / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism; D011981:Receptors, Prolactin / Q000235:genetics*; D020845:Selective Estrogen Receptor Modulators / Q000627:therapeutic use*; D013629:Tamoxifen / Q000627:therapeutic use*; D016387:Women's Health
D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D011981:Receptors, Prolactin; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen