Protein kinase CK2 is important for the function of glioblastoma brain tumor initiating cells
- 776 Downloads
Protein kinase CK2 is a ubiquitously expressed serine/threonine kinase composed of two catalytic subunits (α) and/or (α′) and two regulatory (β) subunits. The expression and kinase activity of CK2 is elevated in many different cancers, including glioblastoma (GBM). Brain tumor initiating cells (BTICs) are a subset of cells that are highly tumorigenic and promote the resistance of GBM to current therapies. We previously reported that CK2 activity promotes prosurvival signaling in GBM. In this study, the role of CK2 signaling in BTIC function was examined. We found that expression of CK2α was increased in CD133+ BTICs compared to CD133− cells within the same GBM xenolines. Treatment with CX-4945, an ATP-competitive inhibitor of CK2, led to reduced expression of Sox2 and Nestin, transcription factors important for the maintenance of stem cells. Similarly, inhibition of CK2 also reduced the frequency of CD133+ BTICs over the course of 7 days, indicating a role for CK2 in BTIC persistence and survival. Importantly, using an in vitro limiting dilution assay, we found that inhibition of CK2 kinase activity with CX-4945 or siRNA knockdown of the CK2 catalytic subunits reduced neurosphere formation in GBM xenolines of different molecular subtypes. Lastly, we found that inhibition of CK2 led to decreased EGFR levels in some xenolines, and combination treatment with CX-4945 and Gefitinib to inhibit CK2 and EGFR, respectively, provided optimal inhibition of viability of cells. Therefore, due to the integration of CK2 in multiple signaling pathways important for BTIC survival, CK2 is a promising target in GBM.
KeywordsGlioblastoma CK2 BTIC CD133 EGFR
We thank Dr. G. Yancey Gillespie and Catherine Langford of the UAB Brain Tumor Animal Models Core Facility (NIH P20CA151129) for assistance, and acknowledge the use of the UAB Rheumatic Diseases Core Center-Comprehensive Flow Cytometry Core (P30 AR048311 and P30 A127667). This work was supported by NIH grants R01CA194414 and R01CA1585340 (E.N.B.), T32NS048039 (A.L.R.), T32AI007051 (S.A.G.), R01CA138517 (S.E.N.) and R01CA1515122 (A.B.H.). Additional funding is from American Brain Tumor Association Discovery Grant (B.C.M.), William E. Cash Jr. Memorial Fund in Neuro-Oncology Research (B.C.M. and S.E.N.), Career Transition Award from the National Multiple Sclerosis Society TA3050-A-1 (G.P.M.), UAB Comprehensive Cancer Center (S.E.N.) and the UAB Brain Tumor SPORE Career Development Award Program via P20CA151129 (A.B.H.).
- 3.Verhaak RG, Hoadley KA, Purdom E, Wang V, Qi Y, Wilkerson MD, Miller CR, Ding L, Golub T, Mesirov JP, Alexe G, Lawrence M, O′Kelly M, Tamayo P, Weir BA, Gabriel S, Winckler W, Gupta S, Jakkula L, Feiler HS, Hodgson JG, James CD, Sarkaria JN, Brennan C, Kahn A, Spellman PT, Wilson RK, Speed TP, Gray JW, Meyerson M, Getz G, Perou CM, Hayes DN, Cancer Genome Atlas Research N (2010) Integrated genomic analysis identifies clinically relevant subtypes of glioblastoma characterized by abnormalities in PDGFRA, IDH1, EGFR, and NF1. Cancer Cell 17(1):98–110CrossRefPubMedPubMedCentralGoogle Scholar
- 4.Ceccarelli M, Barthel FP, Malta TM, Sabedot TS, Salama SR, Murray BA, Morozova O, Newton Y, Radenbaugh A, Pagnotta SM, Anjum S, Wang J, Manyam G, Zoppoli P, Ling S, Rao AA, Grifford M, Cherniack AD, Zhang H, Poisson L, Carlotti CG Jr, Tirapelli DP, Rao A, Mikkelsen T, Lau CC, Yung WK, Rabadan R, Huse J, Brat DJ, Lehman NL, Barnholtz-Sloan JS, Zheng S, Hess K, Rao G, Meyerson M, Beroukhim R, Cooper L, Akbani R, Wrensch M, Haussler D, Aldape KD, Laird PW, Gutmann DH, Noushmehr H, Iavarone A, Verhaak RG (2016) Molecular profiling reveals biologically discrete subsets and pathways of progression in diffuse glioma. Cell 164(3):550–563CrossRefPubMedPubMedCentralGoogle Scholar
- 13.Buchou T, Vernet M, Blond O, Jensen HH, Pointu H, Olsen BB, Cochet C, Issinger OG, Boldyreff B (2003) Disruption of the regulatory beta subunit of protein kinase CK2 in mice leads to a cell-autonomous defect and early embryonic lethality. Mol Cell Biol 23(3):908–915CrossRefPubMedPubMedCentralGoogle Scholar
- 19.Siddiqui-Jain A, Drygin D, Streiner N, Chua P, Pierre F, O′Brien SE, Bliesath J, Omori M, Huser N, Ho C, Proffitt C, Schwaebe MK, Ryckman DM, Rice WG, Anderes K (2010) CX-4945, an orally bioavailable selective inhibitor of protein kinase CK2, inhibits prosurvival and angiogenic signaling and exhibits antitumor efficacy. Cancer Res 70(24):10288–10298CrossRefPubMedGoogle Scholar
- 24.Flavahan WA, Wu Q, Hitomi M, Rahim N, Kim Y, Sloan AE, Weil RJ, Nakano I, Sarkaria JN, Stringer BW, Day BW, Li M, Lathia JD, Rich JN, Hjelmeland AB (2013) Brain tumor initiating cells adapt to restricted nutrition through preferential glucose uptake. Nat Neurosci 16(10):1373–1382CrossRefPubMedPubMedCentralGoogle Scholar
- 29.So KS, Kim CH, Rho JK, Kim SY, Choi YJ, Song JS, Kim WS, Choi CM, Chun YJ, Lee JC (2014) Autophagosome-mediated EGFR down-regulation induced by the CK2 inhibitor enhances the efficacy of EGFR-TKI on EGFR-mutant lung cancer cells with resistance by T790M. PLoS ONE 9(12):e114000CrossRefPubMedPubMedCentralGoogle Scholar
- 31.Mellinghoff IK, Wang MY, Vivanco I, Haas-Kogan DA, Zhu S, Dia EQ, Lu KV, Yoshimoto K, Huang JH, Chute DJ, Riggs BL, Horvath S, Liau LM, Cavenee WK, Rao PN, Beroukhim R, Peck TC, Lee JC, Sellers WR, Stokoe D, Prados M, Cloughesy TF, Sawyers CL, Mischel PS (2005) Molecular determinants of the response of glioblastomas to EGFR kinase inhibitors. N Engl J Med 353(19):2012–2024CrossRefPubMedGoogle Scholar
- 32.Petras M, Lajtos T, Friedlander E, Klekner A, Pintye E, Feuerstein BG, Szollosi J, Vereb G (2013) Molecular interactions of ErbB1 (EGFR) and integrin-beta1 in astrocytoma frozen sections predict clinical outcome and correlate with Akt-mediated in vitro radioresistance. Neuro Oncol 15(8):1027–1040CrossRefPubMedPubMedCentralGoogle Scholar
- 33.Bliesath J, Huser N, Omori M, Bunag D, Proffitt C, Streiner N, Ho C, Siddiqui-Jain A, O′Brien SE, Lim JK, Ryckman DM, Anderes K, Rice WG, Drygin D (2012) Combined inhibition of EGFR and CK2 augments the attenuation of PI3K-Akt-mTOR signaling and the killing of cancer cells. Cancer Lett 322(1):113–118CrossRefPubMedGoogle Scholar
- 34.Zhang S, Yang YL, Wang Y, You B, Dai Y, Chan G, Hsieh D, Kim IJ, Fang L, Au A, Stoppler HJ, Xu Z, Jablons DM, You L (2014) CK2a, over-expressed in human malignant pleural mesothelioma, regulates the Hedgehog signaling pathway in mesothelioma cells. J Exp Clin Cancer Res 33(1):93PubMedPubMedCentralGoogle Scholar