RSK2 protects human breast cancer cells under endoplasmic reticulum stress through activating AMPKα2-mediated autophagy


Autophagy can protect stressed cancer cell by degradation of damaged proteins and organelles. However, the regulatory mechanisms behind this cellular process remain incompletely understood. Here, we demonstrate that RSK2 (p90 ribosomal S6 kinase 2) plays a critical role in ER stress-induced autophagy in breast cancer cells. We demonstrated that the promotive effect of RSK2 on autophagy resulted from directly binding of AMPKα2 in nucleus and phosphorylating it at Thr172 residue. IRE1α, an ER membrane-associated protein mediating unfolded protein response (UPR), is required for transducing the signal for activation of ERK1/2-RSK2 under ER stress. Suppression of autophagy by knockdown of RSK2 enhanced the sensitivity of breast cancer cells to ER stress both in vitro and in vivo. Furthermore, we demonstrated that inhibition of RSK2-mediated autophagy rendered breast cancer cells more sensitive to paclitaxel, a chemotherapeutic agent that induces ER stress-mediated cell death. This study identifies RSK2 as a novel controller of autophagy in tumor cells and suggests that targeting RSK2 can be exploited as an approach to reinforce the efficacy of ER stress-inducing agents against cancer.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: RSK2 promotes autophagy under ER stress in breast cancer cells.
Fig. 2: AMPKα2 is necessary for RSK2-mediated autophagy in breast cancer cells upon ER stress.
Fig. 3: RSK2 directly associates with AMPKα2 and phosphorylates AMPKα2.
Fig. 4: IRE1α/ERK1/2 contributes to RSK2-mediated autophagy upon ER stress.
Fig. 5: Inhibition of RSK2 decreases proliferation and induces apoptosis in breast cancer cells under ER stress.
Fig. 6: Silencing of RSK2 inhibits xenograft tumor growth in vivo.
Fig. 7: Knockdown of RSK2 decreases autophagy, but increases apoptosis and decreases proliferation in human breast cancer cells subjected to paclitaxel.


  1. 1.

    Cheng Y, Ren X, Hait WN, Yang JM. Therapeutic targeting of autophagy in disease: biology and pharmacology. Pharmacol Rev. 2013;65:1162–97.

    CAS  PubMed  PubMed Central  Google Scholar 

  2. 2.

    Nam HY, Han MW, Chang HW, Kim SY, Kim SW. Prolonged autophagy by MTOR inhibitor leads radioresistant cancer cells into senescence. Autophagy. 2013;9:1631–2.

    CAS  PubMed  Google Scholar 

  3. 3.

    He J, Yu JJ, Xu Q, Wang L, Zheng JZ, Liu LZ, et al. Downregulation of ATG14 by EGR1-MIR152 sensitizes ovarian cancer cells to cisplatin-induced apoptosis by inhibiting cyto-protective autophagy. Autophagy. 2015;11:373–84.

    PubMed  PubMed Central  Google Scholar 

  4. 4.

    Lozy F, Cai-McRae X, Teplova I, Price S, Reddy A, Bhanot G, et al. ERBB2 overexpression suppresses stress-induced autophagy and renders ERBB2-induced mammary tumorigenesis independent of monoallelic Becn1 loss. Autophagy. 2014;10:662–76.

    CAS  PubMed  PubMed Central  Google Scholar 

  5. 5.

    Levy JMM, Towers CG, Thorburn A. Targeting autophagy in cancer. Nat Rev Cancer. 2017;17:528–42.

    CAS  PubMed  Google Scholar 

  6. 6.

    Wang M, Kaufman RJ. The impact of the endoplasmic reticulum protein-folding environment on cancer development. Nat Rev Cancer. 2014;14:581–97.

    CAS  PubMed  Google Scholar 

  7. 7.

    Cubillos-Ruiz JR, Bettigole SE, Glimcher LH. Tumorigenic and Immunosuppressive Effects of Endoplasmic Reticulum Stress in. Cancer Cell. 2017;168:692–706.

    CAS  Google Scholar 

  8. 8.

    Shi YH, Ding ZB, Zhou J, Hui B, Shi GM, Ke AW, et al. Targeting autophagy enhances sorafenib lethality for hepatocellular carcinoma via ER stress-related apoptosis. Autophagy. 2011;7:1159–72.

    CAS  PubMed  Google Scholar 

  9. 9.

    Nawrocki ST, Carew JS, Dunner K Jr., Boise LH, Chiao PJ, Huang P, et al. Bortezomib inhibits PKR-like endoplasmic reticulum (ER) kinase and induces apoptosis via ER stress in human pancreatic cancer cells. Cancer Res. 2005;65:11510–9.

    CAS  PubMed  Google Scholar 

  10. 10.

    Lei Y, Henderson BR, Emmanuel C, Harnett PR, deFazio A. Inhibition of ANKRD1 sensitizes human ovarian cancer cells to endoplasmic reticulum stress-induced apoptosis. Oncogene. 2015;34:485–95.

    CAS  PubMed  Google Scholar 

  11. 11.

    Li N, Zoubeidi A, Beraldi E, Gleave ME. GRP78 regulates clusterin stability, retrotranslocation and mitochondrial localization under ER stress in prostate cancer. Oncogene. 2013;32:1933–42.

    CAS  PubMed  Google Scholar 

  12. 12.

    Luan Q, Jin L, Jiang CC, Tay KH, Lai F, Liu XY, et al. RIPK1 regulates survival of human melanoma cells upon endoplasmic reticulum stress through autophagy. Autophagy. 2015;11:975–94.

    CAS  PubMed  PubMed Central  Google Scholar 

  13. 13.

    Li X, Zhu F, Jiang J, Sun C, Zhong Q, Shen M, et al. Simultaneous inhibition of the ubiquitin-proteasome system and autophagy enhances apoptosis induced by ER stress aggravators in human pancreatic cancer cells. Autophagy. 2016;12:1521–37.

    CAS  PubMed  PubMed Central  Google Scholar 

  14. 14.

    Zhao C, Yin S, Dong Y, Guo X, Fan L, Ye M, et al. Autophagy-dependent EIF2AK3 activation compromises ursolic acid-induced apoptosis through upregulation of MCL1 in MCF-7 human breast cancer cells. Autophagy. 2013;9:196–207.

    CAS  PubMed  PubMed Central  Google Scholar 

  15. 15.

    Ciechomska IA, Gabrusiewicz K, Szczepankiewicz AA, Kaminska B. Endoplasmic reticulum stress triggers autophagy in malignant glioma cells undergoing cyclosporine a-induced cell death. Oncogene. 2013;32:1518–29.

    CAS  PubMed  Google Scholar 

  16. 16.

    Cheng Y, Ren X, Zhang Y, Shan Y, Huber-Keener KJ, Zhang L, et al. Integrated regulation of autophagy and apoptosis by EEF2K controls cellular fate and modulates the efficacy of curcumin and velcade against tumor cells. Autophagy. 2013;9:208–19.

    CAS  PubMed  PubMed Central  Google Scholar 

  17. 17.

    Gawecka JE, Young-Robbins SS, Sulzmaier FJ, Caliva MJ, Heikkila MM, Matter ML, et al. RSK2 protein suppresses integrin activation and fibronectin matrix assembly and promotes cell migration. J Biol Chem. 2012;287:43424–37.

    CAS  PubMed  PubMed Central  Google Scholar 

  18. 18.

    Lara R, Seckl MJ, Pardo OE. The p90 RSK family members: common functions and isoform specificity. Cancer Res. 2013;73:5301–8.

    CAS  PubMed  Google Scholar 

  19. 19.

    Houles T, Roux PP. Defining the role of the RSK isoforms in cancer. Semin Cancer Biol. 2018;48:53–61.

    CAS  PubMed  Google Scholar 

  20. 20.

    Cho YY, Yao K, Pugliese A, Malakhova ML, Bode AM, Dong Z. A regulatory mechanism for RSK2 NH(2)-terminal kinase activity. Cancer Res. 2009;69:4398–406.

    CAS  PubMed  PubMed Central  Google Scholar 

  21. 21.

    Piasecka D, Kitowska K, Czaplinska D, Mieczkowski K, Mieszkowska M, Turczyk L, et al. Fibroblast growth factor signalling induces loss of progesterone receptor in breast cancer cells. Oncotarget. 2016;7:86011–25.

    PubMed  PubMed Central  Google Scholar 

  22. 22.

    Stratford AL, Reipas K, Hu K, Fotovati A, Brough R, Frankum J, et al. Targeting p90 ribosomal S6 kinase eliminates tumor-initiating cells by inactivating Y-box binding protein-1 in triple-negative breast cancers. Stem Cells. 2012;30:1338–48.

    CAS  PubMed  Google Scholar 

  23. 23.

    Cho YY, Lee MH, Lee CJ, Yao K, Lee HS, Bode AM, et al. RSK2 as a key regulator in human skin cancer. Carcinogenesis. 2012;33:2529–37.

    CAS  PubMed  PubMed Central  Google Scholar 

  24. 24.

    Eisinger-Mathason TS, Andrade J, Groehler AL, Clark DE, Muratore-Schroeder TL, Pasic L, et al. Codependent functions of RSK2 and the apoptosis-promoting factor TIA-1 in stress granule assembly and cell survival. Mol Cell. 2008;31:722–36.

    CAS  PubMed  PubMed Central  Google Scholar 

  25. 25.

    She QB, Ma WY, Zhong S, Dong Z. Activation of JNK1, RSK2, and MSK1 is involved in serine 112 phosphorylation of Bad by ultraviolet B radiation. J Biol Chem. 2002;277:24039–48.

    CAS  PubMed  Google Scholar 

  26. 26.

    Bonni A, Brunet A, West AE, Datta SR, Takasu MA, Greenberg ME. Cell survival promoted by the Ras-MAPK signaling pathway by transcription-dependent and -independent mechanisms. Science. 1999;286:1358–62.

    CAS  PubMed  Google Scholar 

  27. 27.

    Zhu YX, Yin H, Bruins LA, Shi CX, Jedlowski P, Aziz M, et al. RNA interference screening identifies lenalidomide sensitizers in multiple myeloma, including RSK2. Blood. 2015;125:483–91.

    CAS  PubMed  PubMed Central  Google Scholar 

  28. 28.

    Sulzmaier FJ, Young-Robbins S, Jiang P, Geerts D, Prechtl AM, Matter ML, et al. RSK2 activity mediates glioblastoma invasiveness and is a potential target for new therapeutics. Oncotarget. 2016;7:79869–84.

    PubMed  PubMed Central  Google Scholar 

  29. 29.

    van Jaarsveld MT, Blijdorp IC, Boersma AW, Pothof J, Mathijssen RH, Verweij J, et al. The kinase RSK2 modulates the sensitivity of ovarian cancer cells to cisplatin. Eur J Cancer. 2013;49:345–51.

    PubMed  Google Scholar 

  30. 30.

    Xu L, Su L, Liu X. PKCdelta regulates death receptor 5 expression induced by PS-341 through ATF4-ATF3/CHOP axis in human lung cancer cells. Mol Cancer Ther. 2012;11:2174–82.

    CAS  PubMed  Google Scholar 

  31. 31.

    Fujiki K, Inamura H, Matsuoka M. PI3K signaling mediates diverse regulation of ATF4 expression for the survival of HK-2 cells exposed to cadmium. Arch Toxicol. 2014;88:403–14.

    CAS  PubMed  Google Scholar 

  32. 32.

    Kang S, Chen J. Targeting RSK2 in human malignancies. Expert Opin Ther Targets. 2011;15:11–20.

    CAS  PubMed  Google Scholar 

  33. 33.

    Anjum R, Blenis J. The RSK family of kinases: emerging roles in cellular signalling. Nat Rev Mol Cell Biol. 2008;9:747–58.

    CAS  PubMed  Google Scholar 

  34. 34.

    Wang Q, Wu S, Zhu H, Ding Y, Dai X, Ouyang C, et al. Deletion of PRKAA triggers mitochondrial fission by inhibiting the autophagy-dependent degradation of DNM1L. Autophagy. 2017;13:404–22.

    CAS  PubMed  PubMed Central  Google Scholar 

  35. 35.

    Rao SV, Solum G, Niederdorfer B, Norsett KG, Bjorkoy G, Thommesen L. Gastrin activates autophagy and increases migration and survival of gastric adenocarcinoma cells. BMC Cancer. 2017;17:68.

    PubMed  PubMed Central  Google Scholar 

  36. 36.

    Shin HJ, Kim H, Oh S, Lee JG, Kee M, Ko HJ, et al. AMPK-SKP2-CARM1 signalling cascade in transcriptional regulation of autophagy. Nature. 2016;534:553–7.

    CAS  PubMed  PubMed Central  Google Scholar 

  37. 37.

    Zaouali MA, Boncompagni E, Reiter RJ, Bejaoui M, Freitas I, Pantazi E, et al. AMPK involvement in endoplasmic reticulum stress and autophagy modulation after fatty liver graft preservation: a role for melatonin and trimetazidine cocktail. J Pineal Res. 2013;55:65–78.

    CAS  PubMed  Google Scholar 

  38. 38.

    Qiang L, Sample A, Shea CR, Soltani K, Macleod KF, He YY. Autophagy gene ATG7 regulates ultraviolet radiation-induced inflammation and skin tumorigenesis. Autophagy. 2017;13:2086–103.

    CAS  PubMed  PubMed Central  Google Scholar 

  39. 39.

    Gao J, Fan M, Peng S, Zhang M, Xiang G, Li X, et al. Small-molecule RL71-triggered excessive autophagic cell death as a potential therapeutic strategy in triple-negative breast cancer. Cell Death Dis. 2017;8:e3049.

    CAS  PubMed  PubMed Central  Google Scholar 

  40. 40.

    Maddalena F, Sisinni L, Lettini G, Condelli V, Matassa DS, Piscazzi A, et al. Resistance to paclitxel in breast carcinoma cells requires a quality control of mitochondrial antiapoptotic proteins by TRAP1. Mol Oncol. 2013;7:895–906.

    CAS  PubMed  PubMed Central  Google Scholar 

  41. 41.

    Janczar S, Nautiyal J, Xiao Y, Curry E, Sun M, Zanini E, et al. WWOX sensitises ovarian cancer cells to paclitaxel via modulation of the ER stress response. Cell Death Dis. 2017;8:e2955.

    CAS  PubMed  PubMed Central  Google Scholar 

  42. 42.

    Jeon YJ, Khelifa S, Ratnikov B, Scott DA, Feng Y, Parisi F, et al. Regulation of glutamine carrier proteins by RNF5 determines breast cancer response to ER stress-inducing chemotherapies. Cancer Cell. 2015;27:354–69.

    CAS  PubMed  PubMed Central  Google Scholar 

  43. 43.

    Xu L, Liu JH, Zhang J, Zhang N, Wang ZH. Blockade of autophagy aggravates endoplasmic reticulum stress and improves Paclitaxel cytotoxicity in human cervical cancer cells. Cancer Res Treat. 2015;47:313–21.

    CAS  PubMed  Google Scholar 

  44. 44.

    Wen J, Yeo S, Wang C, Chen S, Sun S, Haas MA, et al. Autophagy inhibition re-sensitizes pulse stimulation-selected paclitaxel-resistant triple negative breast cancer cells to chemotherapy-induced apoptosis. Breast Cancer Res Treat. 2015;149:619–29.

    CAS  PubMed  PubMed Central  Google Scholar 

  45. 45.

    Zhang SF, Wang XY, Fu ZQ, Peng QH, Zhang JY, Ye F, et al. TXNDC17 promotes paclitaxel resistance via inducing autophagy in ovarian cancer. Autophagy. 2015;11:225–38.

    PubMed  PubMed Central  Google Scholar 

  46. 46.

    Liu S, Li X. Autophagy inhibition enhances sensitivity of endometrial carcinoma cells to paclitaxel. Int J Oncol. 2015;46:2399–408.

    CAS  PubMed  Google Scholar 

  47. 47.

    Hospital MA, Jacquel A, Mazed F, Saland E, Larrue C, Mondesir J, et al. RSK2 is a new Pim2 target with pro-survival functions in FLT3-ITD-positive acute myeloid leukemia. Leukemia. 2018;32:597–605.

    CAS  PubMed  Google Scholar 

  48. 48.

    Im JY, Kim BK, Lee JY, Park SH, Ban HS, Jung KE, et al. DDIAS suppresses TRAIL-mediated apoptosis by inhibiting DISC formation and destabilizing caspase-8 in cancer cells. Oncogene. 2018;37:1251–62.

    CAS  PubMed  Google Scholar 

  49. 49.

    Hart LS, Cunningham JT, Datta T, Dey S, Tameire F, Lehman SL, et al. ER stress-mediated autophagy promotes Myc-dependent transformation and tumor growth. J Clin Investig. 2012;122:4621–34.

    CAS  PubMed  Google Scholar 

  50. 50.

    Bhardwaj M, Leli NM, Koumenis C, Amaravadi RK. Regulation of autophagy by canonical and non-canonical ER stress responses. Semin Cancer Biol. 2019. online ahead of print.

  51. 51.

    Spaan CN, Smit WL, van Lidth de Jeude JF, Meijer BJ, Muncan V, van den Brink GR, et al. Expression of UPR effector proteins ATF6 and XBP1 reduce colorectal cancer cell proliferation and stemness by activating PERK signaling. Cell Death Dis. 2019;10:490.

    PubMed  PubMed Central  Google Scholar 

  52. 52.

    Dey S, Tameire F, Koumenis C. PERK-ing up autophagy during MYC-induced tumorigenesis. Autophagy. 2013;9:612–4.

    CAS  PubMed  PubMed Central  Google Scholar 

  53. 53.

    Xiang XY, Yang XC, Su J, Kang JS, Wu Y, Xue YN, et al. Inhibition of autophagic flux by ROS promotes apoptosis during DTT-induced ER/oxidative stress in HeLa cells. Oncol Rep. 2016;35:3471–9.

    CAS  PubMed  Google Scholar 

  54. 54.

    Goncalves RLS, Hotamisligil GS. TMEM2 mdulates ER stress in a non-canonical manner. Cell Metab. 2019;30:999–1001.

    CAS  PubMed  Google Scholar 

  55. 55.

    Tameire F, Verginadis II, Leli NM, Polte C, Conn CS, Ojha R, et al. ATF4 couples MYC-dependent translational activity to bioenergetic demands during tumour progression. Nat Cell Biol. 2019;21:889–99.

    CAS  PubMed  PubMed Central  Google Scholar 

  56. 56.

    Smith MD, Harley ME, Kemp AJ, Wills J, Lee M, Arends M, et al. CCPG1 is a non-canonical autophagy cargo receptor essential for ER-phagy and pancreatic ER proteostasis. Dev Cell. 2018;44:217–32.e11.

    CAS  PubMed  PubMed Central  Google Scholar 

  57. 57.

    Garcia D, Shaw RJ. AMPK: mechanisms of cellular energy sensing and restoration of metabolic balance. Mol Cell. 2017;66:789–800.

    CAS  PubMed  PubMed Central  Google Scholar 

  58. 58.

    Russell RC, Yuan HX, Guan KL. Autophagy regulation by nutrient signaling. Cell Res. 2014;24:42–57.

    CAS  PubMed  Google Scholar 

  59. 59.

    Schaffer BE, Levin RS, Hertz NT, Maures TJ, Schoof ML, Hollstein PE, et al. Identification of AMPK phosphorylation sites reveals a network of proteins involved in cell invasion and facilitates large-scale substrate prediction. Cell Metab. 2015;22:907–21.

    CAS  PubMed  PubMed Central  Google Scholar 

  60. 60.

    Salt IP, Hardie DG. AMP-activated protein kinase: an ubiquitous signaling pathway with key roles in the cardiovascular system. Circ Res. 2017;120:1825–41.

    CAS  PubMed  PubMed Central  Google Scholar 

  61. 61.

    Shang L, Chen S, Du F, Li S, Zhao L, Wang X. Nutrient starvation elicits an acute autophagic response mediated by Ulk1 dephosphorylation and its subsequent dissociation from AMPK. Proc Natl Acad Sci USA. 2011;108:4788–93.

    CAS  PubMed  Google Scholar 

  62. 62.

    Hong-Brown LQ, Brown CR, Navaratnarajah M, Lang CH. FoxO1-AMPK-ULK1 regulates ethanol-induced autophagy in muscle by enhanced ATG14 association with the BECN1-PIK3C3 complex. Alcohol Clin Exp Res. 2017;41:895–910.

    CAS  PubMed  PubMed Central  Google Scholar 

  63. 63.

    Zhang D, Wang W, Sun X, Xu D, Wang C, Zhang Q, et al. AMPK regulates autophagy by phosphorylating BECN1 at threonine 388. Autophagy. 2016;12:1447–59.

    CAS  PubMed  PubMed Central  Google Scholar 

  64. 64.

    Cho YY, He Z, Zhang Y, Choi HS, Zhu F, Choi BY, et al. The p53 protein is a novel substrate of ribosomal S6 kinase 2 and a critical intermediary for ribosomal S6 kinase 2 and histone H3 interaction. Cancer Res. 2005;65:3596–603.

    CAS  PubMed  Google Scholar 

  65. 65.

    Lim HC, Xie L, Zhang W, Li R, Chen ZC, Wu GZ, et al. Ribosomal S6 kinase 2 (RSK2) maintains genomic stability by activating the Atm/p53-dependent DNA damage pathway. PLoS ONE. 2013;8:e74334.

    CAS  PubMed  PubMed Central  Google Scholar 

  66. 66.

    Liu K, Cho YY, Yao K, Nadas J, Kim DJ, Cho EJ, et al. Eriodictyol inhibits RSK2-ATF1 signaling and suppresses EGF-induced neoplastic cell transformation. J Biol Chem. 2011;286:2057–66.

    CAS  PubMed  Google Scholar 

Download references


This work was supported by the National Natural Science Foundation of China under Grant Nos. 81472593 and 81972480; the Postgraduate Research and Innovation Project of Central South University under Grant No. 1053320183910.

Author information



Corresponding author

Correspondence to Yan Cheng.

Ethics declarations

Conflict of interest

The authors declare that they have no conflict of interest.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Li, L., Chen, X., Wang, K. et al. RSK2 protects human breast cancer cells under endoplasmic reticulum stress through activating AMPKα2-mediated autophagy. Oncogene 39, 6704–6718 (2020).

Download citation