title: Ras pathway activation in hepatocellular carcinoma and anti-tumoral effect of combined sorafenib and rapamycin in vivo.
abstract: OBJECTIVE
  The success of sorafenib in the treatment of advanced hepatocellular carcinoma (HCC) has focused interest on the role of Ras signaling in this malignancy. We investigated the molecular alterations of the Ras pathway in HCC and the antineoplastic effects of sorafenib in combination with rapamycin, an inhibitor of mTOR pathway, in experimental models.
  
  
  METHODS
  Gene expression (qRT-PCR, oligonucleotide microarray), DNA copy number changes (SNP-array), methylation of tumor suppressor genes (methylation-specific PCR) and protein activation (immunohistochemistry) were analysed in 351 samples. Anti-tumoral effects of combined therapy targeting the Ras and mTOR pathways were evaluated in cell lines and HCC xenografts.
  
  
  RESULTS
  Different mechanisms accounted for Ras pathway activation in HCC. H-ras was up-regulated during different steps of hepatocarcinogenesis. B-raf was overexpressed in advanced tumors and its expression was associated with genomic amplification. Partial methylation of RASSF1A and NORE1A was detected in 89% and 44% of tumors respectively, and complete methylation was found in 11 and 4% of HCCs. Activation of the pathway (pERK immunostaining) was identified in 10.3% of HCC. Blockade of Ras and mTOR pathways with sorafenib and rapamycin reduced cell proliferation and induced apoptosis in cell lines. In vivo, the combination of both compounds enhanced tumor necrosis and ulceration when compared with sorafenib alone.
  
  
  CONCLUSIONS
  Ras activation results from several molecular alterations, such as methylation of tumor suppressors and amplification of oncogenes (B-raf). Sorafenib blocks signaling and synergizes with rapamycin in vivo, preventing tumor progression. These data provide the rationale for testing this combination in clinical studies.
authors: Mount Sinai Liver Cancer Program, Mount Sinai School of Medicine, 1425 Madison Avenue, New York, NY 10029, USA.
authors: Pippa
authors: P
authors: Newell
authors: Sara
authors: S
authors: Toffanin
authors: Augusto
authors: A
authors: Villanueva
authors: Derek Y
authors: DY
authors: Chiang
authors: Beatriz
authors: B
authors: Minguez
authors: Laia
authors: L
authors: Cabellos
authors: Radoslav
authors: R
authors: Savic
authors: Yujin
authors: Y
authors: Hoshida
authors: Kiat Hon
authors: KH
authors: Lim
authors: Pedro
authors: P
authors: Melgar-Lesmes
authors: Steven
authors: S
authors: Yea
authors: Judit
authors: J
authors: Peix
authors: Kemal
authors: K
authors: Deniz
authors: M Isabel
authors: MI
authors: Fiel
authors: Swan
authors: S
authors: Thung
authors: Clara
authors: C
authors: Alsinet
authors: Victoria
authors: V
authors: Tovar
authors: Vincenzo
authors: V
authors: Mazzaferro
authors: Jordi
authors: J
authors: Bruix
authors: Sasan
authors: S
authors: Roayaie
authors: Myron
authors: M
authors: Schwartz
authors: Scott L
authors: SL
authors: Friedman
authors: Josep M
authors: JM
authors: Llovet
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage*; D001557:Benzenesulfonates / Q000008:administration & dosage*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019175:DNA Methylation / Q000187:drug effects; D004357:Drug Synergism; D005260:Female; D018628:Gene Dosage / Q000187:drug effects; D011905:Genes, ras / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009536:Niacinamide / Q000031:analogs & derivatives; D010671:Phenylurea Compounds; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011494:Protein Kinases / Q000187:drug effects; D011725:Pyridines / Q000008:administration & dosage*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000008:administration & dosage*; D000077157:Sorafenib; D058570:TOR Serine-Threonine Kinases; D014183:Transplantation, Heterologous; D018631:ras Proteins / Q000378:metabolism*
chemical_list: D001557:Benzenesulfonates; D010671:Phenylurea Compounds; D011725:Pyridines; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D009536:Niacinamide; D000077157:Sorafenib; D011494:Protein Kinases; C546842:MTOR protein, human; C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases; D018631:ras Proteins; D020123:Sirolimus