title: RASSF1A-mediated regulation of AREG via the Hippo pathway in hepatocellular carcinoma.
abstract: Ras association domain family 1 isoform A (RASSF1A) is a tumor suppressor that is methylated in many human cancers, including hepatocellular carcinoma (HCC). RASSF1A has been shown to suppress tumors via activation of the Hippo tumor suppressor pathway, including mammalian STE20-like kinase (MST). Amphiregulin (AREG), a target gene for Yes-associated protein (YAP), is a known oncogenic component of the Hippo pathway; however, the tumor-suppressive effect of RASSF1A on AREG in regard to regulation of the Hippo pathway remains unclear in HCC. Overexpression of RASSF1A in HCC cells, which lack functional RASSF1A, significantly inhibited cell proliferation and induced apoptosis by activating the Hippo pathway. Consequently, overexpression of RASSF1A inhibited the oncogenic functions of YAP, leading to a significant reduction in AREG secretion via regulation of the Hippo pathway. In human specimens, greater expression of RASSF1A was observed in chronic hepatitis/cirrhosis than in HCC, whereas expression of YAP and AREG was higher in 81% and 86% of HCC than in corresponding chronic hepatitis/cirrhosis, respectively. Furthermore, RASSF1A protein gradually decreased as multistep hepatocarcinogenesis progressed from chronic hepatitis/cirrhosis dysplastic nodules toward HCC, whereas the protein expression of YAP and AREG gradually increased. These findings provide mechanistic insight into the regulation of YAP and AREG by RASSF1A in human multistep hepatocarcinogenesis.
authors.affiliation: Department of Pathology, Yonsei University College of Medicine, 250 Seongsan-ro, Seodaemun-gu, Seoul, South Korea.
authors.forename: Ei Yong
authors.initials: EY
authors.lastname: Ahn
authors.forename: Ji Su
authors.initials: JS
authors.lastname: Kim
authors.forename: Gi Jeong
authors.initials: GJ
authors.lastname: Kim
authors.forename: Young Nyun
authors.initials: YN
authors.lastname: Park
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000328:Adult; D000368:Aged; D066258:Amphiregulin; D017209:Apoptosis / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019175:DNA Methylation / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics; D066255:EGF Family of Proteins; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D000090683:Hippo Signaling Pathway; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010750:Phosphoproteins / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D015854:Up-Regulation / Q000235:genetics; D000091102:YAP-Signaling Proteins
chemical_list: C587848:AREG protein, human; D048868:Adaptor Proteins, Signal Transducing; D066258:Amphiregulin; D066255:EGF Family of Proteins; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; D010750:Phosphoproteins; C411762:RASSF1 protein, human; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D000091102:YAP-Signaling Proteins; C088374:YAP1 protein, human; D017346:Protein Serine-Threonine Kinases