Up-regulation of thrombospondin-1 gene by epidermal growth factor and transforming growth factor beta in human cancer cells--transcriptional activation and messenger RNA stabilization.
Thrombospondin-1 (TSP-1), a multifunctional matrix protein, affects tumor growth through modulation of angiogenesis and other stromal biological functions. In several of nine human cancer cell lines derived from liver, brain, pancreas, and bone, expression of TSP-1 was up-regulated in response to the two most representative growth factors, epidermal growth factor (EGF) and transforming growth factor beta1 (TGFbeta1). Expression of TSP-1 was markedly enhanced in hepatic HuH-7 cells by EGF but not by TGFbeta1. In contrast, expression of TSP-1 was markedly enhanced by TGFbeta1, but not by EGF, in osteosarcoma MG63 cells. EGF induced activation of TSP-1 promoter-driven luciferase activity in HuH-7 cells, and the elements between -267 and -71 on the 5' region of TSP-1 gene containing two GC boxes to which Sp1 bound, were found to be responsible for the promoter activation by EGF. However, EGF did not alter TSP-1 mRNA stability in hepatic cells. On the other hand, no such enhancement of the TSP-1 promoter activity by TGFbeta1 appeared in MG63 cells. Enhanced expression of TSP-1 by TGFbeta1 in MG63 cells was partially blocked by exogenous addition of SB203580, an inhibitor of p38 mitogen-activated protein kinase. TGFbeta was found to induce marked elongation of TSP-1 mRNA longevity in osteosarcoma cells when mRNA degradation was assayed in the presence of alpha-amanitin. The up-regulation of TSP-1 by EGF and TGFbeta might play a critical role in modulation of angiogenesis and formation of matrices in tumor stroma.
Okamoto
Masahiro
M
Department of Medical Biochemistry, Kyushu University, Fukuoka, Japan. mokamoto@biochem1.med.kyushu-ac.jp
Ono
Mayumi
M
Uchiumi
Takeshi
T
Ueno
Hikaru
H
Kohno
Kimitoshi
K
Sugimachi
Keizo
K
Kuwano
Michihiko
M
D001859:Bone Neoplasms; D006528:Carcinoma, Hepatocellular; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms; D012516:Osteosarcoma; D020871:RNA Stability / Q000187:drug effects*; D019700:Thrombospondin 1 / Q000235:genetics*; D015533:Transcriptional Activation / Q000187:drug effects*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
D019700:Thrombospondin 1; D016212:Transforming Growth Factor beta; D004815:Epidermal Growth Factor