title: Pharmacologic inhibition of Pim kinases alters prostate cancer cell growth and resensitizes chemoresistant cells to taxanes.
abstract: The serine/threonine family of Pim kinases function as oncogenes and have been implicated in prostate cancer progression, particularly in hormone-refractory prostate disease, as a result of their antiapoptotic function. In this study, we used a pharmacologic inhibitor targeting the Pim family members, SGI-1776, to determine whether modulation of Pim kinase activity could alter prostate cancer cell survival and modulate chemotherapy resistance. Extensive biochemical characterization of SGI-1776 confirmed its specificity for the three isoforms of the Pim family. Treatment of prostate cancer cells with SGI-1776 resulted in a dose-dependent reduction in phosphorylation of known Pim kinase substrates that are involved in cell cycle progression and apoptosis (p21(Cip1/WAF1) and Bad). Consequently, SGI-1776 compromised overall cell viability by inducing G(1) cell cycle arrest and triggering apoptosis. Overexpression of recombinant Pim-1 markedly increased sensitivity of SGI-1776-mediated prostate cancer cell apoptosis and p21(Cip1/WAF1) phosphorylation inhibition, reinforcing the specificity of SGI-1776. An additional cytotoxic effect was observed when SGI-1776 was combined with taxane-based chemotherapy agents. SGI-1776 was able to reduce cell viability in a multidrug resistance 1 protein-based taxane-refractory prostate cancer cell line. In addition, SGI-1776 treatment was able to resensitize chemoresistant cells to taxane-based therapies by inhibiting multidrug resistance 1 activity and inducing apoptosis. These findings support the idea that inhibiting Pim kinases, in combination with a chemotherapeutic agent, could play an important role in prostate cancer treatment by targeting the clinical problem of chemoresistance.
authors.affiliation: Sumner M. Redstone Prostate Cancer Research Program, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Mumenthaler
authors.forename: Patricia Y B
authors.initials: PY
authors.lastname: Ng
authors.forename: Amanda
authors.initials: A
authors.lastname: Hodge
authors.forename: David
authors.initials: D
authors.lastname: Bearss
authors.forename: Gregory
authors.initials: G
authors.lastname: Berk
authors.forename: Sarath
authors.initials: S
authors.lastname: Kanekal
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Redkar
authors.forename: Pietro
authors.initials: P
authors.lastname: Taverna
authors.forename: David B
authors.initials: DB
authors.lastname: Agus
authors.forename: Anjali
authors.initials: A
authors.lastname: Jain
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D020169:Caspases / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D006801:Humans; D008297:Male; D017239:Paclitaxel / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology*; D047428:Protein Kinase Inhibitors / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use; D051573:Proto-Oncogene Proteins c-pim-1 / Q000037:antagonists & inhibitors*; D011994:Recombinant Proteins / Q000378:metabolism; D043823:Taxoids / Q000494:pharmacology*
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D047428:Protein Kinase Inhibitors; D011994:Recombinant Proteins; D043823:Taxoids; D051573:Proto-Oncogene Proteins c-pim-1; C406031:proto-oncogene proteins pim; D020169:Caspases; D017239:Paclitaxel