title: Pro-survival responses to the dual inhibition of anti-apoptotic Bcl-2 family proteins and mTOR-mediated signaling in hypoxic colorectal carcinoma cells.
abstract: The use of targeted agents to impel dual inhibition of anti-apoptotic mechanisms and mTOR-mediated pro-survival signaling in colorectal carcinoma (CRC) cell lines with KRAS or BRAF mutation has been shown to induce apoptosis, a timely result given CRC entities harboring such mutations are in need of new therapies. Since CRC comprises heterogeneous tumors with predominant hypoxic components, we investigated effects of an inhibitor of anti-apoptotic Bcl-2 family proteins (ABT-737) in combination with an mTOR inhibitor (AZD8055)-collectively referred to as combo-Rx, in hypoxic CRC cell lines.
  
  
  
  Cell viability measures, expression of proteins implicated in apoptosis and MAPK/PI3K-AKT/mTOR pathway signaling, and profiling of composite kinase activities were undertaken in a panel of 14 cell lines.
  
  
  
  In hypoxic conditions, combo-Rx suppressed viability of 13 of the cell lines, albeit ABT-737 did not significantly potentiate the inhibitory effect of single-agent AZD8055 in six of the models. Hypoxic KRAS/PIK3CA-mutant HCT-116 and HCT-15 cell lines (both with low endogenous expression of the anti-apoptotic Mcl-1 protein and showing augmented inhibition of viability following the addition of ABT-737 to AZD8055) responded to combo-Rx by induction of apoptosis but with the simultaneous strong Mcl-1 up-regulation and activation of MAPK/PI3K-conducted signaling. In contrast, in hypoxic KRAS-mutant LoVo (devoid of PIK3CA mutation), BRAF/PIK3CA-mutant RKO, and wild-type Colo320DM cell lines (all with high endogenous Mcl-1 expression and being resistant to the additional effect of ABT-737 to AZD8055), combo-Rx did not elicit apoptotic or pro-survival responses.
  
  
  
  The concurrent inhibition of anti-apoptotic proteins and mTOR-mediated signaling in hypoxic KRAS/PIK3CA-mutant CRC cell lines resulted in pro-survival responses in parallel with the intended anti-proliferative effects, a finding that should be of note if considering combinatory targeting of multiple pathways in this CRC entity.
authors.affiliation: Department of Oncology, Akershus University Hospital, 1478, Lørenskog, Norway.|Institute of Clinical Molecular Biology, Akershus University Hospital, 1478, Lørenskog, Norway.
authors.forename: Karianne
authors.initials: K
authors.lastname: Risberg
authors.affiliation: Department of Oncology, Akershus University Hospital, 1478, Lørenskog, Norway.
authors.forename: Kathrine Røe
authors.initials: KR
authors.lastname: Redalen
authors.affiliation: Department of Oncology, Akershus University Hospital, 1478, Lørenskog, Norway.
authors.forename: Linda
authors.initials: L
authors.lastname: Sønstevold
authors.affiliation: Department of Oncology, Akershus University Hospital, 1478, Lørenskog, Norway.|Institute of Clinical Medicine, University of Oslo, 0318, Oslo, Norway.
authors.forename: Tonje
authors.initials: T
authors.lastname: Bjørnetrø
authors.affiliation: Department of Oncology, Akershus University Hospital, 1478, Lørenskog, Norway.
authors.forename: Janne
authors.initials: J
authors.lastname: Sølvernes
authors.affiliation: Department of Oncology, Akershus University Hospital, 1478, Lørenskog, Norway. a.h.ree@medisin.uio.no.|Institute of Clinical Medicine, University of Oslo, 0318, Oslo, Norway. a.h.ree@medisin.uio.no.
authors.forename: Anne Hansen
authors.initials: AH
authors.lastname: Ree
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001713:Biphenyl Compounds / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D058534:Class I Phosphatidylinositol 3-Kinases / Q000235:genetics; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology*; D009154:Mutation; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000378:metabolism; D009596:Nitrophenols / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors*; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013449:Sulfonamides / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000072258:Tumor Hypoxia; D015854:Up-Regulation
chemical_list: C501332:ABT-737; D000970:Antineoplastic Agents; D001713:Biphenyl Compounds; D004791:Enzyme Inhibitors; C117307:KRAS protein, human; C579095:MCL1 protein, human; D009025:Morpholines; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009596:Nitrophenols; D010879:Piperazines; D019253:Proto-Oncogene Proteins c-bcl-2; D013449:Sulfonamides; C546624:(5-(2,4-bis((3S)-3-methylmorpholin-4-yl)pyrido(2,3-d)pyrimidin-7-yl)-2-methoxyphenyl)methanol; C546842:MTOR protein, human; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases; D016283:Proto-Oncogene Proteins p21(ras)
keywords: ABT-737; AZD8055; Apoptosis; Colorectal cancer; Hypoxia; KRAS; Kinase activity; Mcl-1; PIK3CA