title: Akt inhibitors MK-2206 and nelfinavir overcome mTOR inhibitor resistance in diffuse large B-cell lymphoma.
abstract: OBJECTIVE
  The mTOR pathway is constitutively activated in diffuse large B-cell lymphoma (DLBCL). mTOR inhibitors have activity in DLBCL, although response rates remain low. We evaluated DLBCL cell lines with differential resistance to the mTOR inhibitor rapamycin: (i) to identify gene expression profile(s) (GEP) associated with resistance to rapamycin, (ii) to understand mechanisms of rapamycin resistance, and (iii) to identify compounds likely to synergize with mTOR inhibitor.
  
  
  METHODS
  We sought to identify a GEP of mTOR inhibitor resistance by stratification of eight DLBCL cell lines with respect to response to rapamycin. Then, using pathway analysis and connectivity mapping, we sought targets likely accounting for this resistance and compounds likely to overcome it. We then evaluated two compounds thus identified for their potential to synergize with rapamycin in DLBCL and confirmed mechanisms of activity with standard immunoassays.
  
  
  RESULTS
  We identified a GEP capable of reliably distinguishing rapamycin-resistant from rapamycin-sensitive DLBCL cell lines. Pathway analysis identified Akt as central to the differentially expressed gene network. Connectivity mapping identified compounds targeting Akt as having a high likelihood of reversing the GEP associated with mTOR inhibitor resistance. Nelfinavir and MK-2206, chosen for their Akt-inhibitory properties, yielded synergistic inhibition of cell viability in combination with rapamycin in DLBCL cell lines, and potently inhibited phosphorylation of Akt and downstream targets of activated mTOR.
  
  
  CONCLUSIONS
  GEP identifies DLBCL subsets resistant to mTOR inhibitor therapy. Combined targeting of mTOR and Akt suppresses activation of key components of the Akt/mTOR pathway and results in synergistic cytotoxicity. These findings are readily adaptable to clinical trials.
authors.affiliation: Montefiore Medical Center, Bronx, New York, USA.
authors.forename: Adam M
authors.initials: AM
authors.lastname: Petrich
authors.forename: Violetta
authors.initials: V
authors.lastname: Leshchenko
authors.forename: Pei-Yu
authors.initials: PY
authors.lastname: Kuo
authors.forename: Bing
authors.initials: B
authors.lastname: Xia
authors.forename: Venu K
authors.initials: VK
authors.lastname: Thirukonda
authors.forename: Netha
authors.initials: N
authors.lastname: Ulahannan
authors.forename: Shanisha
authors.initials: S
authors.lastname: Gordon
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Fazzari
authors.forename: B Hilda
authors.initials: BH
authors.lastname: Ye
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Sparano
authors.forename: Samir
authors.initials: S
authors.lastname: Parekh
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D017320:HIV Protease Inhibitors / Q000494:pharmacology; D006575:Heterocyclic Compounds, 3-Ring / Q000494:pharmacology*; D006801:Humans; D007124:Immunoenzyme Techniques; D016403:Lymphoma, Large B-Cell, Diffuse / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D019888:Nelfinavir / Q000494:pharmacology*; D020411:Oligonucleotide Array Sequence Analysis; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D017320:HIV Protease Inhibitors; D006575:Heterocyclic Compounds, 3-Ring; D019888:Nelfinavir; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D020123:Sirolimus; D058570:TOR Serine-Threonine Kinases; C548887:MK 2206; C546842:MTOR protein, human