Transforming Growth Factor-β1 Produced by Ovarian Cancer Cell Line HRA Stimulates Attachment and Invasion through an Up-regulation of Plasminogen Activator Inhibitor Type-1 in Human Peritoneal Mesothelial Cells

Abstract

The processes of ovarian cancer dissemination are characterized by altered local proteolysis, cellular proliferation, cell attachment, and invasion, suggesting that the urokinase-type plasminogen activator (uPA) and its specific inhibitor (plasminogen activator inhibitor type-1 (PAI-1)) could be involved in the pathogenesis of peritoneal dissemination. We showed previously that expression of uPA and PAI-1 in the human ovarian cancer cell line HRA can be down-regulated by exogenous bikunin (bik), a Kunitz-type protease inhibitor, via suppression of transforming growth factor-␤1 (TGF-␤1) up-regulation and that overexpression of the bik gene can specifically suppress the in vivo growth and peritoneal dissemination of HRA cells in an animal model. We hypothesize that the plasminogen activator system in mesothelial cells can be modulated by HRA cells. To test this hypothesis, we used complementary techniques in mesothelial cells to determine whether uPA and PAI-1 expression are altered by exposure to culture media conditioned by HRA cells. Here we show the following: 1) that expression of PAI-1, but not uPA, was markedly induced by culture media conditioned by wild-type HRA cells but not by bik transfected clones; 2) that by antibody neutralization the effect appeared to be mediated by HRA cell-derived TGF-␤1; 3) that exogenous TGF-␤1 specifically enhanced PAI-1 up-regulation at the mRNA and protein level in mesothelial cells in a timeand concentration-dependent manner, mainly through MAPK-dependent activation mechanism; and 4) that mesothelial cell-derived PAI-1 may promote tumor invasion possibly by enhancing cell-cell interaction. This represents a novel pathway by which tumor cells can regulate the plasminogen activator system-dependent cellular responses in mesothelial cells that may contribute to formation of peritoneal dissemination of ovarian cancer.

TGF-β and HGF transmit the signals through JNK-dependent Smad2/3 phosphorylation at the linker regions

“…Plasminogen activator inhibitor type 1 (PAI-1), the main inhibitor of the urokinase-type plasminogen activator system, conducts the cells to migration and invasion by blocking cellular adhesion and by promoting basement membrane degradation (Gutierrez et al, 2000). Moreover, PAI-1-induced TGF-b signal stimulates attachment and invasion in primary ovarian cancer cells (Hirashima et al, 2003). Therefore, we investigated whether HGF and TGF-b regulated PAI-1 expression in RGM-1 cells.…”

Transforming Growth Factor-β1-dependent Urokinase Up-regulation and Promotion of Invasion Are Involved in Src-MAPK-dependent Signaling in Human Ovarian Cancer Cells

“…The processes of ovarian cancer dissemination are characterized by altered local proteolysis, cellular proliferation, cell attachment, and invasion, suggesting that the urokinase-type plasminogen activator (uPA) 1 could be involved in the pathogenesis of peritoneal dissemination (1). uPA is a serine protease associated with various pathological conditions including tumor invasion and metastasis (2).…”

“…uPA is a serine protease associated with various pathological conditions including tumor invasion and metastasis (2). One of the factors regulating the metastatic process is considered to be transforming growth factor-␤ (TGF-␤), which is a multifunctional cytokine that elicits numerous cellular effects pertinent to the metastatic process (1). TGF-␤ regulates a wide range of physiological and pathological cellular processes, including cell growth, differentiation, invasion, migration, mesenchymal transition, extracellular matrix synthesis, and cell death in many cell types including ovarian cancer cells (3).…”

“…TGF-␤ regulates a wide range of physiological and pathological cellular processes, including cell growth, differentiation, invasion, migration, mesenchymal transition, extracellular matrix synthesis, and cell death in many cell types including ovarian cancer cells (3). Recent data demonstrated that TGF-␤ specifically stimulates up-regulation of uPA mRNA and protein in certain types of neoplastic cells (1). The cellular mechanism(s) of the TGF-␤-induced uPA-dependent tumor invasion and metastasis has been extensively studied.…”

“…: 81-53-435-2309; Fax: 81-53-435-2308; E-mail: hirokoba@hama-med.ac.jp. 1 The abbreviations used are: uPA, urokinase-type plasminogen activator; AS, antisense; iAS, inverted antisense; S, sense; ERK, extracellular signal-regulated kinase; MAPK, mitogen-activated protein kinase; ODN, oligodeoxynucleotide; PDTC, pyrrolidinedithiocarbamate; PI3K, phosphoinositide-3-kinase; TGF-␤, transforming growth factor-␤; STAT, signal transducers and activators of transcription.…”