title: RNA-directed DNA polymerase activity in human breast cancer biopsy specimens. Relation to estrogen receptor protein.
abstract: The expression of a mouse mammary tumor virus is inducible by hormones, and the virus contains a hormone-responsive element. Viral particles and RNA-directed DNA polymerase (RDDP, EC 2.7.7.7; reverse transcriptase) are both detectable in human breast tumors but the frequency and significance of these findings are unknown. Breast tumor biopsy specimens (from either the primary site or a metastasis), frozen in liquid nitrogen at the time of surgery, were routinely obtained to determine estrogen receptor (ERP) concentration. A sample of the tissue was pulverized, homogenized and centrifuged at low speed to remove nuclei and mitochondria. The supernate was then centrifuged at 225,000 g to obtain the cytosol fraction for estrogen and progestin receptor (PgR) assays. Partially purified membranes for the RDDP assays were prepared from the high-speed pellet by discontinuous sucrose density gradient centrifugation. The RDDP assay involved measuring primer-dependent poly(dT) synthesis in the presence of poly(A) as template and oligo-(dT)12-18 as primer. To date, we have studied biopsy specimens from 46 patients with breast cancer. 27 (59%) had ERP and 23 (50%) were RDDP-positive. There was no significant correlation between ERP concentration and RDDP activity. PgR data were available on 36 of the patients; 17 (47%) were positive. No correlation between RDDP and PgR was apparent. Similarly, there was no correlation between RDDP and clinical stage of the disease.
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D001943:Breast Neoplasms / Q000032:analysis* / Q000209:etiology; D002458:Cell Fractionation; D002462:Cell Membrane / Q000032:analysis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D009367:Neoplasm Staging; D010298:Parity; D012194:RNA-Directed DNA Polymerase / Q000032:analysis*; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis; D012042:Registries
chemical_list: D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D012194:RNA-Directed DNA Polymerase