title: TSC1/2mutations define a molecular subset of HCC with aggressive behaviour and treatment implication.
abstract: We investigated the mutational landscape of mammalian target of rapamycin (mTOR) signalling cascade in hepatocellular carcinomas (HCCs) with chronic HBV background, aiming to evaluate and delineate mutation-dependent mechanism of mTOR hyperactivation in hepatocarcinogenesis.
  
  
  
  We performed next-generation sequencing on human HCC samples and cell line panel. Systematic mutational screening of mTOR pathway-related genes was undertaken and mutant genes were evaluated based on their recurrence. Protein expressions of tuberous sclerosis complex (TSC)1, TSC2 and pRPS6 were assessed by immunohistochemistry in human HCC samples. Rapamycin sensitivity was estimated by colony-formation assay in HCC cell lines and the treatment was further tested using our patient-derived tumour xenograft (PDTX) models.
  
  
  
  We identified and confirmed multiple mTOR components as recurrently mutated in HBV-associated HCCs. Of significance, we detected frequent (16.2%, n=18/111) mutations ofTSC1andTSC2genes in the HCC samples. The spectrum ofTSC1/2mutations likely disrupts the endogenous gene functions in suppressing the downstream mTOR activity through different mechanisms and leads to more aggressive tumour behaviour. Mutational disruption ofTSC1andTSC2was also observed in HCC cell lines and our PDTX models.TSC-mutant cells exhibited reduced colony-forming ability on rapamycin treatment. With the use of biologically relevantTSC2-mutant PDTXs, we demonstrated the therapeutic benefits of the hypersensitivity towards rapamycin treatment.
  
  
  
  Taken together, our findings suggest the significance of previously undocumented mutation-dependent mTOR hyperactivation and frequentTSC1/2mutations in HBV-associated HCCs. They define a molecular subset of HCC having genetic aberrations in mTOR signalling, with potential significance of effective specific drug therapy.
authors.affiliation: Department of Pathology, The University of Hong Kong, Hong Kong, Hong Kong.|State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong, Hong Kong.
authors.forename: Daniel W H
authors.identifier: 0000-0003-3884-296X
authors.initials: DWH
authors.lastname: Ho
authors.affiliation: Department of Pathology, The University of Hong Kong, Hong Kong, Hong Kong.|State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong, Hong Kong.
authors.forename: Lo K
authors.initials: LK
authors.lastname: Chan
authors.affiliation: Department of Pathology, The University of Hong Kong, Hong Kong, Hong Kong.|State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong, Hong Kong.
authors.forename: Yung T
authors.initials: YT
authors.lastname: Chiu
authors.affiliation: Department of Pathology, The University of Hong Kong, Hong Kong, Hong Kong.|State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong, Hong Kong.
authors.forename: Iris M J
authors.initials: IMJ
authors.lastname: Xu
authors.affiliation: State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong, Hong Kong.|Department of Surgery, The University of Hong Kong, Hong Kong, Hong Kong.
authors.forename: Ronnie T P
authors.initials: RTP
authors.lastname: Poon
authors.affiliation: Department of Surgery, The University of Hong Kong, Hong Kong, Hong Kong.
authors.forename: Tan T
authors.initials: TT
authors.lastname: Cheung
authors.affiliation: Department of Surgery, Pamela Youde Hospital, Hong Kong, Hong Kong.
authors.forename: Chung N
authors.initials: CN
authors.lastname: Tang
authors.affiliation: Department of Pathology, Pamela Youde Hospital, Hong Kong, Hong Kong.
authors.forename: Victor W L
authors.initials: VWL
authors.lastname: Tang
authors.affiliation: Department of Surgery, Queen Elizabeth Hospital, Hong Kong, Hong Kong.
authors.forename: Irene L O
authors.initials: ILO
authors.lastname: Lo
authors.affiliation: Department of Pathology, Queen Elizabeth Hospital, Hong Kong, Hong Kong.
authors.forename: Polly W Y
authors.initials: PWY
authors.lastname: Lam
authors.affiliation: Department of Pathology, Queen Elizabeth Hospital, Hong Kong, Hong Kong.
authors.forename: Derek T W
authors.initials: DTW
authors.lastname: Yau
authors.affiliation: Department of Psychiatry and Center for Genomics Science, The University of Hong Kong, Hong Kong, Hong Kong.
authors.forename: Miao X
authors.initials: MX
authors.lastname: Li
authors.affiliation: Department of Pathology, The University of Hong Kong, Hong Kong, Hong Kong.|State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong, Hong Kong.
authors.forename: Chun M
authors.initials: CM
authors.lastname: Wong
authors.affiliation: Department of Pathology, The University of Hong Kong, Hong Kong, Hong Kong.|State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong, Hong Kong.
authors.forename: Irene O L
authors.initials: IOL
authors.lastname: Ng
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology / Q000627:therapeutic use*; D060466:Axin Protein / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D008875:Middle Aged; D059645:Mutation Rate; D009368:Neoplasm Transplantation; D009687:Nuclear Proteins / Q000235:genetics; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology / Q000627:therapeutic use*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics; D000077004:Tuberous Sclerosis Complex 1 Protein; D000077005:Tuberous Sclerosis Complex 2 Protein; D014410:Tumor Stem Cell Assay; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000032:analysis / Q000235:genetics*; D055815:Young Adult; D051176:beta Catenin / Q000235:genetics
chemical_list: C112476:ARID1A protein, human; C555451:AXIN1 protein, human; D000903:Antibiotics, Antineoplastic; D060466:Axin Protein; C495270:CTNNB1 protein, human; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C000624650:TSC1 protein, human; C000624653:TSC2 protein, human; D014157:Transcription Factors; C000624651:Tsc1 protein, mouse; C000624654:Tsc2 protein, mouse; D000077004:Tuberous Sclerosis Complex 1 Protein; D000077005:Tuberous Sclerosis Complex 2 Protein; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D051176:beta Catenin; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus
keywords: GENE MUTATION; HEPATITIS B; HEPATOCELLULAR CARCINOMA; MUTATION SCREENING