TGF-beta inactivation and TGF-alpha overexpression cooperate in an in vivo mouse model to induce hepatocellular carcinoma that recapitulates molecular features of human liver cancer.
Hepatocellular carcinoma (HCC) results from the cumulative effects of deregulated tumor suppressor genes and oncogenes. The tumor suppressor and oncogenes commonly affected include growth factors, receptors and their downstream signaling pathway components. The overexpression of transforming growth factor alpha (TGF-alpha) and the inhibition of TGF-beta signaling are especially common in human liver cancer. Thus, we assessed whether TGF-alpha overexpression and TGF-beta signaling inactivation cooperate in hepatocarcinogenesis using an in vivo mouse model, MT1/TGFa;AlbCre/Tgfbr2(flx/flx) mice ("TGFa;Tgfbr2(hepko)"), which overexpresses TGF-alpha and lacks a TGF-beta receptor in the liver. TGF-beta signaling inactivation did not alter the frequency or number of cancers in mice with overexpression of TGF-alpha. However, the tumors in the TGFa;Tgfbr2(hepko) mice displayed increased proliferation and increased cdk2, cyclin E and cyclin A expression as well as decreased Cdkn1a/p21 expression compared to normal liver and compared to the cancers arising in the TGF-alpha overexpressing mice with intact TGF-beta receptors. Increased phosphorylated ERK1/2 expression was also present in the tumors from the TGFa;Tgfbr2(hepko) mice and correlated with downregulated Raf kinase inhibitor protein expression, which is a common molecular event in human HCC. Thus, TGF-beta signaling inactivation appears to cooperate with TGF-alpha in vivo to promote the formation of liver cancer that recapitulates molecular features of human HCC.
Baek
Ji Yeon
JY
Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Republic of Korea.
Morris
Shelli M
SM
Campbell
Jean
J
Fausto
Nelson
N
Yeh
Matthew M
MM
Grady
William M
WM
D000818:Animals; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007124:Immunoenzyme Techniques; D019426:Integrases / Q000378:metabolism; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D016211:Transforming Growth Factor alpha / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000502:physiology*
D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D016211:Transforming Growth Factor alpha; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II; C045073:Cre recombinase; D019426:Integrases