Article

BRAF inhibition upregulates a variety of receptor tyrosine kinases and their downstream effector Gab2 in colorectal cancer cell lines

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Abstract

BRAF mutations occur in ~10% of colorectal cancer (CRC) and are associated with poor prognosis. Inhibitors selective for the BRAFV600E oncoprotein, the most common BRAF mutant, elicit only poor response rates in BRAF-mutant CRC as single agents. This unresponsiveness was mechanistically attributed to the loss of negative feedbacks on the epidermal growth factor receptor (EGFR) and initiated clinical trials that combine BRAF (and MEK) inhibitors, either singly or in combination, with the anti-EGFR antibodies cetuximab or panitumumab. First results of these combinatorial studies demonstrated improved efficacy, however, the response rates still were heterogeneous. Here, we show that BRAF inhibition leads to the upregulation of a variety of receptor tyrosine kinases (RTKs) in CRC cell lines, including not only the EGFR, but also human epidermal growth factor receptor (HER) 2 and HER3. Importantly, combination of the BRAF inhibitors (BRAFi) vemurafenib (PLX4032), dabrafenib, or encorafenib with inhibitors dually targeting the EGFR and HER2 (such as lapatinib, canertinib, and afatinib) significantly reduced the metabolic activity and proliferative potential of CRC cells. This re-sensitization was also observed after genetic depletion of HER2 or HER3. Interestingly, BRAF inhibitors did not only upregulate RTKs, but also increased the abundance of the GRB2-associated binders (Gab) 1 and Gab2, two important amplifiers of RTK signaling. An allele-specific shRNA-mediated knockdown of BRAFV600E revealed that Gab2 upregulation was directly dependent on the loss of the oncoprotein and was not caused by an “off-target” effect of these kinase inhibitors. Furthermore, Gab2 and Gab2-mediated Shp2 signaling were shown to be functionally important in BRAFi resistance. These findings highlight potential new escape mechanisms to these targeted therapies and indicate that a broad suppression of RTK signaling might be beneficial and should be taken into account in future research addressing targeted therapy in BRAF-mutant CRC.

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References

  1. 1.

    Fleuren ED, Zhang L, Wu J, Daly RJ. The kinome ‘at large’ in cancer. Nat Rev Cancer. 2016;16:83–98.

  2. 2.

    Little AS, Smith PD, Cook SJ. Mechanisms of acquired resistance to ERK1/2 pathway inhibitors. Oncogene. 2013;32:1207–15.

  3. 3.

    Smith MP, Wellbrock C. Molecular pathways: maintaining MAPK inhibitor sensitivity by targeting non-mutational tolerance. Clin Cancer Res. 2016;22:5966–70.

  4. 4.

    Chapman PB, Hauschild A, Robert C, Haanen JB, Ascierto P, Larkin J, et al. Improved survival with vemurafenib in melanoma with BRAF V600E mutation. N Engl J Med. 2011;364:2507–16.

  5. 5.

    Clarke CN, Kopetz ES. BRAF mutant colorectal cancer as a distinct subset of colorectal cancer: clinical characteristics, clinical behavior, and response to targeted therapies. J Gastrointest Oncol. 2015;6:660–7.

  6. 6.

    Tran B, Kopetz S, Tie J, Gibbs P, Jiang ZQ, Lieu CH, et al. Impact of BRAF mutation and microsatellite instability on the pattern of metastatic spread and prognosis in metastatic colorectal cancer. Cancer. 2011;117:4623–32.

  7. 7.

    Yaeger R, Cercek A, Chou JF, Sylvester BE, Kemeny NE, Hechtman JF, et al. BRAF mutation predicts for poor outcomes after metastasectomy in patients with metastatic colorectal cancer. Cancer. 2014;120:2316–24.

  8. 8.

    Kopetz S, Desai J, Chan E, Hecht JR, O’Dwyer PJ, Maru D, et al. Phase II pilot study of vemurafenib in patients with metastatic BRAF-mutated colorectal cancer. J Clin Oncol. 2015;33:4032–8.

  9. 9.

    Prahallad A, Sun C, Huang S, Di Nicolantonio F, Salazar R, Zecchin D, et al. Unresponsiveness of colon cancer to BRAF(V600E) inhibition through feedback activation of EGFR. Nature. 2012;483:100–3.

  10. 10.

    Corcoran RB, Ebi H, Turke AB, Coffee EM, Nishino M, Cogdill AP, et al. EGFR-mediated reactivation of MAPK signaling contributes to insensitivity of BRAF mutant colorectal cancers to RAF inhibition with vemurafenib. Cancer Discov. 2012;2:227–35.

  11. 11.

    Kolch W, Halasz M, Granovskaya M, Kholodenko BN. The dynamic control of signal transduction networks in cancer cells. Nat Rev Cancer. 2015;15:515–27.

  12. 12.

    Di Nicolantonio F, Martini M, Molinari F, Sartore-Bianchi A, Arena S, Saletti P, et al. Wild-type BRAF is required for response to panitumumab or cetuximab in metastatic colorectal cancer. J Clin Oncol. 2008;26:5705–12.

  13. 13.

    Montero-Conde C, Ruiz-Llorente S, Dominguez JM, Knauf JA, Viale A, Sherman EJ, et al. Relief of feedback inhibition of HER3 transcription by RAF and MEK inhibitors attenuates their anti-tumor effects in BRAF-mutant thyroid carcinomas. Cancer Discov. 2013;3:520–33.

  14. 14.

    Wilson TR, Fridlyand J, Yan Y, Penuel E, Burton L, Chan E, et al. Widespread potential for growth-factor-driven resistance to anticancer kinase inhibitors. Nature. 2012;487:505–9.

  15. 15.

    Straussman R, Morikawa T, Shee K, Barzily-Rokni M, Qian ZR, Du J, et al. Tumour micro-environment elicits innate resistance to RAF inhibitors through HGF secretion. Nature. 2012;487:500–4.

  16. 16.

    Nazarian R, Shi H, Wang Q, Kong X, Koya RC, Lee H, et al. Melanomas acquire resistance to B-RAF(V600E) inhibition by RTK or N-RAS upregulation. Nature. 2010;468:973–7.

  17. 17.

    Abel EV, Basile KJ, Kugel CH, Witkiewicz AK, Le K, Amaravadi RK, et al. Melanoma adapts to RAF/MEK inhibitors through FOXD3-mediated upregulation of ERBB3. J Clin Invest. 2013;123:2155–68.

  18. 18.

    Ahronian LG, Sennott EM, Van Allen EM, Wagle N, Kwak EL, Faris JE, et al. Clinical acquired resistance to RAF inhibitor combinations in BRAF-mutant colorectal cancer through MAPK pathway alterations. Cancer Discov. 2015;5:358–67.

  19. 19.

    Williams CB, McMahon C, Ali SM, Abramovitz M, Williams KA, Klein J, et al. A metastatic colon adenocarcinoma harboring BRAF V600E has a durable major response to dabrafenib/trametinib and chemotherapy. OncoTargets Ther. 2015;8:3561–4.

  20. 20.

    Corcoran RB, Atreya CE, Falchook GS, Kwak EL, Ryan DP, Bendell JC, et al. Combined BRAF and MEK inhibition with dabrafenib and trametinib in BRAF V600-mutant colorectal cancer. J Clin Oncol. 2015;33:4023–31.

  21. 21.

    Yaeger R, Cercek A, O’Reilly EM, Reidy DL, Kemeny N, Wolinsky T, et al. Pilot trial of combined BRAF and EGFR inhibition in BRAF-mutant metastatic colorectal cancer patients. Clin Cancer Res. 2015;21:1313–20.

  22. 22.

    Hong DS, Morris VK, El Osta B, Sorokin AV, Janku F, Fu S, et al. Phase 1B study of vemurafenib in combination with irinotecan and cetuximab in patients with metastatic colorectal cancer with BRAF V600E mutation. Cancer Discov. 2016;6:1352–65.

  23. 23.

    Connolly K, Brungs D, Szeto E, Epstein RJ. Anticancer activity of combination targeted therapy using cetuximab plus vemurafenib for refractory BRAF (V600E)-mutant metastatic colorectal carcinoma. Curr Oncol. 2014;21:e151–154.

  24. 24.

    Sundar R, Hong DS, Kopetz S, Yap TA. Targeting BRAF-mutant colorectal cancer: progress in combination strategies. Cancer Discov. 2017;7:558–60.

  25. 25.

    Wohrle FU, Daly RJ, Brummer T. Function, regulation and pathological roles of the Gab/DOS docking proteins. Cell Commun Signal. 2009;7:22.

  26. 26.

    Wöhrle FU, Daly RJ, Brummer T. How to Grb2 a Gab. Structure. 2009;17:779–81.

  27. 27.

    Wöhrle FU, Halbach S, Aumann K, Schwemmers S, Braun S, Auberger P, et al. Gab2 signaling in chronic myeloid leukemia cells confers resistance to multiple Bcr-Abl inhibitors. Leukemia. 2013;27:118–29.

  28. 28.

    Halbach S, Hu Z, Gretzmeier C, Ellermann J, Wöhrle FU, Dengjel J, et al. Axitinib and sorafenib are potent in tyrosine kinase inhibitor resistant chronic myeloid leukemia cells. Cell Commun Signal. 2016;14:6.

  29. 29.

    Hoeben A, Martin D, Clement PM, Cools J, Gutkind JS. Role of GRB2-associated binder 1 in epidermal growth factor receptor-induced signaling in head and neck squamous cell carcinoma. Int J Cancer. 2013;132:1042–50.

  30. 30.

    Halbach S, Kohler M, Uhl FM, Huber J, Zeiser R, Koschmieder S, et al. Gab2 is essential for Bcr-Abl-mediated leukemic transformation and hydronephrosis in a chronic myeloid leukemia mouse model. Leukemia. 2016;30:1942–5.

  31. 31.

    Liu W, Yu WM, Zhang J, Chan RJ, Loh ML, Zhang Z, et al. Inhibition of the Gab2/PI3K/mTOR signaling ameliorates myeloid malignancy caused by Ptpn11 (Shp2) gain-of-function mutations. Leukemia. 2017;31:1415–22.

  32. 32.

    Bentires-Alj M, Gil SG, Chan R, Wang ZC, Wang Y, Imanaka N, et al. A role for the scaffolding adapter GAB2 in breast cancer. Nat Med. 2006;12:114–21.

  33. 33.

    Klinger B, Sieber A, Fritsche-Guenther R, Witzel F, Berry L, Schumacher D, et al. Network quantification of EGFR signaling unveils potential for targeted combination therapy. Mol Syst Biol. 2013;9:673.

  34. 34.

    Herr R, Kohler M, Andrlova H, Weinberg F, Moller Y, Halbach S, et al. B-Raf inhibitors induce epithelial differentiation in BRAF-mutant colorectal cancer cells. Cancer Res. 2015;75:216–29.

  35. 35.

    Bollag G, Hirth P, Tsai J, Zhang J, Ibrahim PN, Cho H, et al. Clinical efficacy of a RAF inhibitor needs broad target blockade in BRAF-mutant melanoma. Nature. 2010;467:596–9.

  36. 36.

    King AJ, Arnone MR, Bleam MR, Moss KG, Yang J, Fedorowicz KE, et al. Dabrafenib; preclinical characterization, increased efficacy when combined with trametinib, while BRAF/MEK tool combination reduced skin lesions. PLoS ONE. 2013;8:e67583.

  37. 37.

    Peng SB, Henry JR, Kaufman MD, Lu WP, Smith BD, Vogeti S, et al. Inhibition of RAF isoforms and active dimers by LY3009120 leads to anti-tumor activities in RAS or BRAF mutant cancers. Cancer Cell. 2015;28:384–98.

  38. 38.

    Cagnol S, Rivard N. Oncogenic KRAS and BRAF activation of the MEK/ERK signaling pathway promotes expression of dual-specificity phosphatase 4 (DUSP4/MKP2) resulting in nuclear ERK1/2 inhibition. Oncogene. 2013;32:564–76.

  39. 39.

    Pratilas CA, Taylor BS, Ye Q, Viale A, Sander C, Solit DB, et al. V600E)BRAF is associated with disabled feedback inhibition of RAF-MEK signaling and elevated transcriptional output of the pathway. Proc Natl Acad Sci USA. 2009;106:4519–24.

  40. 40.

    Kidger AM, Keyse SM. The regulation of oncogenic Ras/ERK signalling by dual-specificity mitogen activated protein kinase phosphatases (MKPs). Semin Cell Dev Biol. 2016;50:125–32.

  41. 41.

    Zhang Z, Kobayashi S, Borczuk AC, Leidner RS, Laframboise T, Levine AD, et al. Dual specificity phosphatase 6 (DUSP6) is an ETS-regulated negative feedback mediator of oncogenic ERK signaling in lung cancer cells. Carcinogenesis. 2010;31:577–86.

  42. 42.

    Batlle E, Bacani J, Begthel H, Jonkheer S, Jonkeer S, Gregorieff A, et al. EphB receptor activity suppresses colorectal cancer progression. Nature. 2005;435:1126–30.

  43. 43.

    Jubb AM, Zhong F, Bheddah S, Grabsch HI, Frantz GD, Mueller W, et al. EphB2 is a prognostic factor in colorectal cancer. Clin Cancer Res. 2005;11:5181–7.

  44. 44.

    Hafner C, Schmitz G, Meyer S, Bataille F, Hau P, Langmann T, et al. Differential gene expression of Eph receptors and ephrins in benign human tissues and cancers. Clin Chem. 2004;50:490–9.

  45. 45.

    Cortina C, Palomo-Ponce S, Iglesias M, Fernandez-Masip JL, Vivancos A, Whissell G, et al. EphB-ephrin-B interactions suppress colorectal cancer progression by compartmentalizing tumor cells. Nat Genet. 2007;39:1376–83.

  46. 46.

    Yarden Y, Sliwkowski MX. Untangling the ErbB signalling network. Nat Rev Mol Cell Biol. 2001;2:127–37.

  47. 47.

    Olayioye MA, Neve RM, Lane HA, Hynes NE. The ErbB signaling network: receptor heterodimerization in development and cancer. EMBO J. 2000;19:3159–67.

  48. 48.

    Gala K, Chandarlapaty S. Molecular pathways: HER3 targeted therapy. Clin Cancer Res. 2014;20:1410–6.

  49. 49.

    Medico E, Russo M, Picco G, Cancelliere C, Valtorta E, Corti G, et al. The molecular landscape of colorectal cancer cell lines unveils clinically actionable kinase targets. Nat Commun. 2015;6:7002.

  50. 50.

    Vincent KM, Postovit LM. Investigating the utility of human melanoma cell lines as tumour models. Oncotarget. 2017;8:10498–509.

  51. 51.

    Rad R, Cadinanos J, Rad L, Varela I, Strong A, Kriegl L, et al. A genetic progression model of braf-induced intestinal tumorigenesis reveals targets for therapeutic intervention. Cancer Cell. 2013;24:15–29.

  52. 52.

    Karaman MW, Herrgard S, Treiber DK, Gallant P, Atteridge CE, Campbell BT, et al. A quantitative analysis of kinase inhibitor selectivity. Nat Biotechnol. 2008;26:127–32.

  53. 53.

    Radic-Sarikas B, Halasz M, Huber KVM, Winter GE, Tsafou KP, Papamarkou T, et al. Lapatinib potentiates cytotoxicity of YM155 in neuroblastoma via inhibition of the ABCB1 efflux transporter. Sci Rep. 2017;7:3091.

  54. 54.

    Carraway KL. E3 ubiquitin ligases in ErbB receptor quantity control. Semin Cell Dev Biol. 2010;21:936–43.

  55. 55.

    Das Thakur M, Salangsang F, Landman AS, Sellers WR, Pryer NK, Levesque MP, et al. Modelling vemurafenib resistance in melanoma reveals a strategy to forestall drug resistance. Nature. 2013;494:251–5.

  56. 56.

    Nörz D, Grottke A, Bach J, Herzberger C, Hofmann BT, Nashan B, et al. Discontinuing MEK inhibitors in tumor cells with an acquired resistance increases migration and invasion. Cell Signal. 2015;27:2191–2200.

  57. 57.

    Boerries M, Herr R, Brummer T, Busch H. Global gene expression profiling analysis reveals reduction of stemness after B-RAF inhibition in colorectal cancer cell lines. Genom Data. 2015;4:158–61.

  58. 58.

    Mao M, Tian F, Mariadason JM, Tsao CC, Lemos R, Dayyani F, et al. Resistance to BRAF inhibition in BRAF-mutant colon cancer can be overcome with PI3K inhibition or demethylating agents. Clin Cancer Res. 2013;19:657–67.

  59. 59.

    Xiang S, Wang N, Hui P, Ma J. Gab3 is required for human colorectal cancer cell proliferation. Biochem Biophys Res Commun. 2017;484:719–25.

  60. 60.

    Klijn C, Durinck S, Stawiski EW, Haverty PM, Jiang Z, Liu H, et al. A comprehensive transcriptional portrait of human cancer cell lines. Nat Biotechnol. 2015;33:306–12.

  61. 61.

    Chernoff KA, Bordone L, Horst B, Simon K, Twadell W, Lee K, et al. GAB2 amplifications refine molecular classification of melanoma. Clin Cancer Res. 2009;15:4288–91.

  62. 62.

    Daly RJ, Gu H, Parmar J, Malaney S, Lyons RJ, Kairouz R, et al. The docking protein Gab2 is overexpressed and estrogen regulated in human breast cancer. Oncogene. 2002;21:5175–81.

  63. 63.

    Lynch DK, Daly RJ. PKB-mediated negative feedback tightly regulates mitogenic signalling via Gab2. EMBO J. 2002;21:72–82.

  64. 64.

    Brummer T, Schramek D, Hayes VM, Bennett HL, Caldon CE, Musgrove EA, et al. Increased proliferation and altered growth factor dependence of human mammary epithelial cells overexpressing the Gab2 docking protein. J Biol Chem. 2006;281:626–37.

  65. 65.

    Castellano E, Sheridan C, Thin MZ, Nye E, Spencer-Dene B, Diefenbacher ME, et al. Requirement for interaction of PI3-kinasep110α with RAS in lung tumor maintenance. Cancer Cell. 2013;24:617–30.

  66. 66.

    Gu H, Pratt JC, Burakoff SJ, Neel BG. Cloning of p97/Gab2, the major SHP2-binding protein in hematopoietic cells, reveals a novel pathway for cytokine-induced gene activation. Mol Cell. 1998;2:729–40.

  67. 67.

    Prahallad A, Heynen GJ, Germano G, Willems SM, Evers B, Vecchione L, et al. PTPN11 is a central node in intrinsic and acquired resistance to targeted cancer drugs. Cell Rep. 2015;12:1978–85.

  68. 68.

    Schwarz LJ, Hutchinson KE, Rexer BN, Estrada MV, Gonzalez Ericsson PI, Sanders ME, et al. An ERBB1-3 neutralizing antibody mixture with high activity against drug-resistant HER2+ breast cancers with ERBB ligand overexpression. J Natl Cancer Inst. 2017;109:djx065.

  69. 69.

    Ellebaek S, Brix S, Grandal M, Lantto J, Horak ID, Kragh M, et al. Pan-HER-An antibody mixture targeting EGFR, HER2 and HER3 abrogates preformed and ligand-induced EGFR homo- and heterodimers. Int J Cancer. 2016;139:2095–105.

  70. 70.

    Oddo D, Sennott EM, Barault L, Valtorta E, Arena S, Cassingena A, et al. Molecular landscape of acquired resistance to targeted therapy combinations in BRAF-mutant colorectal cancer. Cancer Res. 2016;76:4504–15.

  71. 71.

    Caenepeel S, Cooke K, Wadsworth S, Huang G, Robert L, Moreno BH, et al. MAPK pathway inhibition induces MET and GAB1 levels, priming BRAF mutant melanoma for rescue by hepatocyte growth factor. Oncotarget. 2017;8:17795–809.

  72. 72.

    Hugo W, Shi H, Sun L, Piva M, Song C, Kong X, et al. Non-genomic and immune evolution of melanoma acquiring MAPKi resistance. Cell. 2015;162:1271–85.

  73. 73.

    Fattore L, Malpicci D, Marra E, Belleudi F, Noto A, De Vitis C, et al. Combination of antibodies directed against different ErbB3 surface epitopes prevents the establishment of resistance to BRAF/MEK inhibitors in melanoma. Oncotarget. 2015;6:24823–41.

  74. 74.

    Kugel CH, Hartsough EJ, Davies MA, Setiady YY, Aplin AE. Function-blocking ERBB3 antibody inhibits the adaptive response to RAF inhibitor. Cancer Res. 2014;74:4122–32.

  75. 75.

    Chaussepied M, Ginsberg D. Transcriptional regulation of AKT activation by E2F. Mol Cell. 2004;16:831–7.

  76. 76.

    Yang L, Ma Y, Han W, Li W, Cui L, Zhao X, et al. Proteinase-activated receptor 2 promotes cancer cell migration through RNA methylation-mediated repression of miR-125b. J Biol Chem. 2015;290:26627–37.

  77. 77.

    Bai R, Weng C, Dong H, Li S, Chen G, Xu Z. MicroRNA-409-3p suppresses colorectal cancer invasion and metastasis partly by targeting GAB1 expression. Int J Cancer. 2015;137:2310–22.

  78. 78.

    Halbach S, Rigbolt KT, Wöhrle FU, Diedrich B, Gretzmeier C, Brummer T, et al. Alterations of Gab2 signalling complexes in imatinib and dasatinib treated chronic myeloid leukaemia cells. Cell Commun Signal. 2013;11:30.

  79. 79.

    Ortiz-Padilla C, Gallego-Ortega D, Browne BC, Hochgräfe F, Caldon CE, Lyons RJ, et al. Functional characterization of cancer-associated Gab1 mutations. Oncogene. 2013;32:2696–702.

  80. 80.

    Duckworth C, Zhang L, Carroll SL, Ethier SP, Cheung HW. Overexpression of GAB2 in ovarian cancer cells promotes tumor growth and angiogenesis by upregulating chemokine expression. Oncogene. 2016;35:4036–47.

  81. 81.

    Wang Y, Sheng Q, Spillman MA, Behbakht K, Gu H. Gab2 regulates the migratory behaviors and E-cadherin expression via activation of the PI3K pathway in ovarian cancer cells. Oncogene. 2012;31:2512–20.

  82. 82.

    Fleuren ED, O’Toole S, Millar EK, McNeil C, Lopez-Knowles E, Boulghourjian A, et al. Overexpression of the oncogenic signal transducer Gab2 occurs early in breast cancer development. Int J Cancer. 2010;127:1486–92.

  83. 83.

    Matsumura T, Sugimachi K, Takahashi Y, Uchi R, Sawada G, Ueda M, et al. Clinical significance of GAB2, a scaffolding/docking protein acting downstream of EGFR in human colorectal cancer. Ann Surg Oncol. 2014;21:S743–749.

  84. 84.

    Ding C, Luo J, Yu W, Gao S, Yang L, Chen C, et al. Gab2 is a novel prognostic factor for colorectal cancer patients. Int J Clin Exp Pathol. 2015;8:2779–86.

  85. 85.

    Ding C, Luo J, Fan X, Li L, Li S, Wen K, et al. Elevated Gab2 induces tumor growth and angiogenesis in colorectal cancer through upregulating VEGF levels. J Exp Clin Cancer Res. 2017;36:56.

  86. 86.

    Bier D, Bartel M, Sies K, Halbach S, Higuchi Y, Haranosono Y, et al. Small-molecule stabilization of the 14-3-3/Gab2 protein-protein interaction (PPI) interface. ChemMedChem. 2016;11:911–8.

  87. 87.

    Herrera Abreu MT, Hughes WE, Mele K, Lyons RJ, Rickwood D, Browne BC, et al. Gab2 regulates cytoskeletal organization and migration of mammary epithelial cells by modulating RhoA activation. Mol Biol Cell. 2011;22:105–16.

  88. 88.

    Bennett HL, Brummer T, Jeanes A, Yap AS, Daly RJ. Gab2 and Src co-operate in human mammary epithelial cells to promote growth factor independence and disruption of acinar morphogenesis. Oncogene. 2008;27:2693–704.

  89. 89.

    Horst B, Gruvberger-Saal SK, Hopkins BD, Bordone L, Yang Y, Chernoff KA, et al. Gab2-mediated signaling promotes melanoma metastasis. Am J Pathol. 2009;174:1524–33.

  90. 90.

    Röring M, Herr R, Fiala GJ, Heilmann K, Braun S, Eisenhardt AE, et al. Distinct requirement for an intact dimer interface in wild-type, V600E and kinase-dead B-Raf signalling. EMBO J. 2012;31:2629–47.

  91. 91.

    Li X, Lin Z, Zhang B, Guo L, Liu S, Li H, et al. β-elemene sensitizes hepatocellular carcinoma cells to oxaliplatin by preventing oxaliplatin-induced degradation of copper transporter 1. Sci Rep. 2016;6:21010.

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Acknowledgements

We thank Martin Köhler for valuable discussions, Roland Rad for sharing MouseT1 cells, and Silke Kowar for expert technical assistance. This work was supported by the German Research Foundation (DFG) through SFB 850, projects B4 (TB) and Z1 (HB and MB), a Heisenberg professorship to TB, EXC 294 BIOSS and the BMBF through e:Bio 0316184D, and MB within the framework of the e:Med research and funding concept, DeCaRe (FKZ 01ZX1409B).

Author contributions

RH, SH, and TB designed the research and performed data analysis. RH, SH, and MH performed the experiments. HB and MB analyzed the microarray data. RH wrote the manuscript together with TB.

Author information

Affiliations

  1. Signal Transduction in Tumour Development and Drug Resistance Group, Institute of Molecular Medicine and Cell Research (IMMZ), Faculty of Medicine, University of Freiburg, Freiburg, Germany

    • Ricarda Herr
    • , Sebastian Halbach
    • , Miriam Heizmann
    •  & Tilman Brummer
  2. Faculty of Biology, University of Freiburg, Freiburg, Germany

    • Miriam Heizmann
  3. Systems Biology of the Cellular Microenvironment, IMMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany

    • Hauke Busch
    •  & Melanie Boerries
  4. Institute of Experimental Dermatology and Institute of Cardiogenetics, University of Lübeck, Lübeck, Germany

    • Hauke Busch
  5. German Cancer Consortium (DKTK) Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany

    • Melanie Boerries
    •  & Tilman Brummer
  6. Comprehensive Cancer Centre Freiburg (CCCF), University of Freiburg, Freiburg, Germany

    • Melanie Boerries
    •  & Tilman Brummer
  7. Centre for Biological Signalling Studies (BIOSS), University of Freiburg, Freiburg, Germany

    • Tilman Brummer

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Conflict of interest

The authors declare that they have no competing interests.

Corresponding authors

Correspondence to Ricarda Herr or Tilman Brummer.

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