title: Overexpression of transforming growth factor (TGF) beta1 type II receptor restores TGF-beta1 sensitivity and signaling in human prostate cancer cells.
abstract: TGF-beta1 is a potent negative regulator of cell growth that transduces signals through interaction with type I and type II receptors that form a heteroduplex. Abnormal expression and mutational alterations of these receptors have recently been shown in several human malignancies. In previous studies, we have demonstrated reduced expression of both types of transforming growth factor (TGF) beta1 receptors in human prostate tumors. In this study, using the human prostate cancer cell line, LNCaP, which is refractory to TGF-beta1 and lacks type II receptor (R-II), we investigated whether overexpression of the R-II receptor can restore sensitivity to the negative growth effects of TGF-beta1. LNCaP cells were transfected with plasmid containing the full length of human TGF-beta R-II receptor cDNA sequence. Stable transfectant clones were selected for R-II mRNA and protein expression by Northern and Western analyses, respectively. The effect of TGF-beta on LNCaP R-II overexpressing clones was examined on the basis of: (a) growth inhibition (cell number); (b) DNA synthesis using the [3H]thymidine incorporation assay; (c) induction of cyclin-dependent-kinase inhibitors, p21WAF-1/Cip1, p27Kip1, and p15; and (d) colony-forming ability in soft agar. Both the cell number and the rate of DNA synthesis of R-II-overexpressing clones were significantly suppressed by exogenous TGF-beta1 in a dose-dependent manner, compared with control cell lines. Treatment of R-II cloned transfectants with TGF-beta1 induced a G1 arrest, which was accompanied by a transient increase in p21WAF-1/Cip1 and p27Kip1 expression at the mRNA and protein level. Furthermore, the LNCaP R-II transfectants analyzed exhibited a markedly reduced colony-forming ability. Our results indicate that overexpression of TGF-beta1 R-II receptor in LNCaP prostate cancer cells caused tumor growth inhibition by restoring the TGF-beta signaling mechanism and TGF-beta1 sensitivity.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore 21201, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Guo
authors.forename: N
authors.initials: N
authors.lastname: Kyprianou
mesh_terms: D002352:Carrier Proteins / Q000096:biosynthesis; D018797:Cell Cycle Proteins; D002455:Cell Division; D003114:Colony-Forming Units Assay; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D016213:Cyclins / Q000096:biosynthesis; D015870:Gene Expression; D006801:Humans; D008297:Male; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis; D017430:Prostate-Specific Antigen / Q000096:biosynthesis; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism* / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
chemical_list: C493956:CDKN1A protein, human; C493966:CDKN2B protein, human; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D008869:Microtubule-Associated Proteins; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D017346:Protein Serine-Threonine Kinases; D018844:Cyclin-Dependent Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II; D017430:Prostate-Specific Antigen