title: Kinome-Wide RNA Interference Screen Reveals a Role for PDK1 in Acquired Resistance to CDK4/6 Inhibition in ER-Positive Breast Cancer.
abstract: Acquired resistance to cyclin-dependent kinases 4 and 6 (CDK4/6) small-molecule inhibitors in breast cancer arises through mechanisms that are yet uncharacterized. In this study, we used a kinome-wide siRNA screen to identify kinases that, when downregulated, yield sensitivity to the CDK4/6 inhibitor ribociclib. In this manner, we identified 3-phosphoinositide-dependent protein kinase 1 (PDK1) as a key modifier of ribociclib sensitivity in estrogen receptor-positive MCF-7 breast cancer cells. Pharmacologic inhibition of PDK1 with GSK2334470 in combination with ribociclib or palbociclib, another CDK4/6 inhibitor, synergistically inhibited proliferation and increased apoptosis in a panel of ER-positive breast cancer cell lines. Ribociclib-resistant breast cancer cells selected by chronic drug exposure displayed a relative increase in the levels of PDK1 and activation of the AKT pathway. Analysis of these cells revealed that CDK4/6 inhibition failed to induce cell-cycle arrest or senescence. Mechanistic investigations showed that resistant cells coordinately upregulated expression of cyclins A, E, and D1, activated phospho-CDK2, and phospho-S477/T479 AKT. Treatment with GSK2334470 or the CDK2 inhibitor dinaciclib was sufficient to reverse these events and to restore the sensitivity of ribociclib-resistant cells to CDK4/6 inhibitors. Ribociclib, in combination with GSK2334470 or the PI3Kα inhibitor alpelisib, decreased xenograft tumor growth more potently than each drug alone. Taken together, our results highlight a role for the PI3K-PDK1 signaling pathway in mediating acquired resistance to CDK4/6 inhibitors.Cancer Res; 77(9); 2488-99. ©2017 AACR.
authors.affiliation: Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Valerie M
authors.initials: VM
authors.lastname: Jansen
authors.affiliation: Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Neil E
authors.initials: NE
authors.lastname: Bhola
authors.affiliation: Department of Biochemistry, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.|Vanderbilt Institute of Chemical Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Bauer
authors.affiliation: Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Luigi
authors.initials: L
authors.lastname: Formisano
authors.affiliation: Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Kyung-Min
authors.initials: KM
authors.lastname: Lee
authors.affiliation: Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Hutchinson
authors.affiliation: Department of Pathology, University of Arizona, Tucson, Arizona.
authors.forename: Agnieszka K
authors.initials: AK
authors.lastname: Witkiewicz
authors.affiliation: Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Preston D
authors.initials: PD
authors.lastname: Moore
authors.affiliation: Breast Cancer Program, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Mónica Valéria
authors.initials: MV
authors.lastname: Estrada
authors.affiliation: Breast Cancer Program, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Violeta
authors.initials: V
authors.lastname: Sánchez
authors.affiliation: Breast Cancer Program, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Paula G
authors.initials: PG
authors.lastname: Ericsson
authors.affiliation: Department of Pathology, Microbiology and Immunology, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Melinda E
authors.initials: ME
authors.lastname: Sanders
authors.affiliation: Department of Medicine, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC.
authors.forename: Paula R
authors.initials: PR
authors.lastname: Pohlmann
authors.affiliation: Department of Medicine, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pishvaian
authors.affiliation: Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: David A
authors.initials: DA
authors.lastname: Riddle
authors.affiliation: Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Teresa C
authors.initials: TC
authors.lastname: Dugger
authors.affiliation: Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
authors.forename: Wenyi
authors.initials: W
authors.lastname: Wei
authors.affiliation: Department of Medicine, University of Arizona, Tucson, Arizona.
authors.forename: Erik S
authors.initials: ES
authors.lastname: Knudsen
authors.affiliation: Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee. carlos.arteaga@vanderbilt.edu.|Breast Cancer Program, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.|Department of Cancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Carlos L
authors.initials: CL
authors.lastname: Arteaga
mesh_terms: D000631:Aminopyridines / Q000008:administration & dosage*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D051358:Cyclin-Dependent Kinase 4 / Q000037:antagonists & inhibitors / Q000235:genetics; D051361:Cyclin-Dependent Kinase 6 / Q000037:antagonists & inhibitors / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics*; D004357:Drug Synergism; D005260:Female; D006801:Humans; D007191:Indazoles / Q000008:administration & dosage; D061986:MCF-7 Cells; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics; D010879:Piperazines / Q000008:administration & dosage; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics*; D011687:Purines / Q000008:administration & dosage*; D011725:Pyridines / Q000008:administration & dosage; D011743:Pyrimidines / Q000008:administration & dosage; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D011960:Receptors, Estrogen / Q000037:antagonists & inhibitors / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D000631:Aminopyridines; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D007191:Indazoles; D019869:Phosphatidylinositol 3-Kinases; D010879:Piperazines; D017346:Protein Serine-Threonine Kinases; D011687:Purines; D011725:Pyridines; D011743:Pyrimidines; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D011960:Receptors, Estrogen; C555257:GSK 2334470; C000631429:PDK1 protein, human; C000631433:Pdk1 protein, mouse; C495900:CDK4 protein, human; C500026:palbociclib; C000589651:ribociclib