title: Lysophosphatidic acid-induced p21Waf1 expression mediates the cytostatic response of breast and ovarian cancer cells to TGFβ.
abstract: Lysophosphatidic acid (LPA) is a multifunctional intercellular phospholipid mediator present in blood and other biological fluids. In cancer cells, LPA stimulates expression or activity of inflammatory cytokines, angiogenic factors, matrix metalloproteinases, and other oncogenic proteins. In this study, we showed that LPA upregulated expression of the cyclin-dependent kinase inhibitor p21(Waf1) in TGFβ-sensitive breast and ovarian cancer cells, but not in TGFβ-resistant ones. We examined the possibility that LPA-induced p21 might contribute to the cytostatic response to TGFβ. In serum-free conditions, TGFβ alone induced p21 expression weakly in TGFβ-sensitive cells. Serum or serum-borne LPA cooperated with TGFβ to elicit the maximal p21 induction. LPA stimulated p21 via LPA(1) and LPA(2) receptors and Erk-dependent activation of the CCAAT/enhancer binding protein beta transcription factor independent of p53. Loss or gain of p21 expression led to a shift between TGFβ-sensitive and -resistant phenotypes in breast and ovarian cancer cells, indicating that p21 is a key determinant of the growth inhibitory activity of TGFβ. Our results reveal a novel cross-talk between LPA and TGFβ that underlies TGFβ-sensitive and -resistant phenotypes of breast and ovarian cancer cells.
authors: Virginia Commonwealth University School of Medicine, Department of Biochemistry and Molecular Biology, Richmond, VA 23298, USA.
authors: Jinhua
authors: J
authors: Wu
authors: Abir
authors: A
authors: Mukherjee
authors: Deborah A
authors: DA
authors: Lebman
authors: Xianjun
authors: X
authors: Fang
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D045744:Cell Line, Tumor; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis*; D004357:Drug Synergism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008246:Lysophospholipids / Q000494:pharmacology*; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D010766:Phosphorylation; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology*
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D008246:Lysophospholipids; D016212:Transforming Growth Factor beta; C032881:lysophosphatidic acid