title: A human B-lymphoblastoid cell line produces prolactin.
abstract: A variety of cell lines were examined by Northern blot hybridization for the expression of PRL or PRL-related mRNAs. We found that a human B-lymphoblast cell line transcribed a mRNA which hybridized to human PRL cDNA under high stringency conditions. The human lymphoblast cell line of interest is a variant subline of the IM-9 line that we have designated IM-9-P. The lymphoblast-derived PRL mRNA is approximately 150 bases longer than that produced by the human pituitary as determined by Northern blot analysis. IM-9-P PRL was immunoaffinity purified from conditioned medium and found to be identical in mol wt by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to human pituitary PRL. Moreover, IM-9-P PRL is biologically active in the rat Nb2 lymphoma mitogenic assay. Ribonuclease-H digestion of mRNA poly(A) tracts indicated that the size difference between pituitary and IM-9-P PRL transcripts was not due to an elongated poly(A) tail on the lymphoid PRL mRNA. Genomic Southern blot analysis showed no major rearrangements of the PRL gene in IM-9-P cells compared to the parent IM-9 line and human placenta DNA. Thus, it is highly likely that an elongation of the 5' and/or 3' untranslated regions of IM-9-P PRL mRNA account for the size difference with pituitary PRL mRNA. The PRL-producing IM-9-P line was cloned by limiting dilution, and a high PRL-producing clone IM-9-P3 and a non-PRL producer IM-9-P6 were isolated for further analysis. IM-9-P3 cells were found to secrete 40-50 ng PRL/10(6) cells.24 h regardless of cell density. The level of PRL mRNA also remained constant during exponential growth of IM-9-P3 cells. The existence of the PRL-producing IM-9-P3 clone and the IM-9-P6 clone which does not produce PRL as well as the IM-9 progenitor line provides a unique system with which to analyze the molecular mechanism of ectopic human PRL expression.
authors.affiliation: Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
authors.forename: G E
authors.initials: GE
authors.lastname: DiMattia
authors.forename: B
authors.initials: B
authors.lastname: Gellersen
authors.forename: H G
authors.initials: HG
authors.lastname: Bohnet
authors.forename: H G
authors.initials: HG
authors.lastname: Friesen
mesh_terms: D000911:Antibodies, Monoclonal; D001402:B-Lymphocytes / Q000378:metabolism*; D002460:Cell Line; D004247:DNA; D004591:Electrophoresis, Polyacrylamide Gel; D004722:Endoribonucleases / Q000378:metabolism; D005260:Female; D005803:Genes, Immunoglobulin; D006801:Humans; D007118:Immunoassay; D007074:Immunoglobulin G / Q000378:metabolism; D009101:Multiple Myeloma; D009693:Nucleic Acid Hybridization; D011388:Prolactin / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D011863:Radioimmunoassay; D016914:Ribonuclease H; D014158:Transcription, Genetic
chemical_list: D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D012333:RNA, Messenger; D011388:Prolactin; D004247:DNA; D004722:Endoribonucleases; D016914:Ribonuclease H