title: Elevation of receptor tyrosine kinases by small molecule AKT inhibitors in prostate cancer is mediated by Pim-1.
abstract: The PI3K/AKT pathway is hyperactivated in prostate cancer but its effective therapeutic targeting has proven difficult. In particular, the antitumor activity of AKT inhibitors is attenuated by upregulation of receptor tyrosine kinases (RTK) through an uncharacterized feedback mechanism. In this report, we show that RNA interference-mediated silencing or pharmacologic inhibition of Pim-1 activity curtails AKT inhibitor-induced upregulation of RTKs in prostate cancer cells. Although Pim kinases have been implicated in cap-dependent translational control, we find that in the context of AKT inhibition, the expression of RTKs is controlled by Pim-1 in a cap-independent manner by controlling internal ribosome entry. Combination of Pim and AKT inhibitors resulted in synergistic inhibition of prostate tumor growth in vitro and in vivo. Together, our results show that Pim-1 mediates resistance to AKT inhibition and suggest its targeting to improve the efficacy of AKT inhibitors in anticancer therapy.
authors.affiliation: Department of Medicine, and The Hollings Cancer Center, Medical University of South Carolina, Charleston, SC29425, USA. cen@musc.edu
authors.forename: Bo
authors.initials: B
authors.lastname: Cen
authors.forename: Sandeep
authors.initials: S
authors.lastname: Mahajan
authors.forename: Wenxue
authors.initials: W
authors.lastname: Wang
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Kraft
mesh_terms: D000818:Animals; D048708:Cell Growth Processes / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D006367:HeLa Cells; D064593:Heterografts; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D051573:Proto-Oncogene Proteins c-pim-1 / Q000235:genetics / Q000378:metabolism*; D011897:Random Allocation; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection
chemical_list: D047428:Protein Kinase Inhibitors; D019869:Phosphatidylinositol 3-Kinases; D020794:Receptor Protein-Tyrosine Kinases; D051057:Proto-Oncogene Proteins c-akt; D051573:Proto-Oncogene Proteins c-pim-1