Dietlein F, Kalb B, Jokic M, Noll EM, Strong A, Tharun L, Ozretić L, Künstlinger H, Kambartel K, Randerath WJ, Jüngst C, Schmitt A, Torgovnick A, Richters A, Rauh D, Siedek F, Persigehl T, Mauch C, Bartkova J, Bradley A, Sprick MR, Trumpp A, Rad R, Saur D, Bartek J, Wolf J, Büttner R, Thomas RK, Reinhardt HC
Cell 162 (1) 146-159 [2015-07-02; online 2015-07-04]
KRAS is one of the most frequently mutated oncogenes in human cancer. Despite substantial efforts, no clinically applicable strategy has yet been developed to effectively treat KRAS-mutant tumors. Here, we perform a cell-line-based screen and identify strong synergistic interactions between cell-cycle checkpoint-abrogating Chk1- and MK2 inhibitors, specifically in KRAS- and BRAF-driven cells. Mechanistically, we show that KRAS-mutant cancer displays intrinsic genotoxic stress, leading to tonic Chk1- and MK2 activity. We demonstrate that simultaneous Chk1- and MK2 inhibition leads to mitotic catastrophe in KRAS-mutant cells. This actionable synergistic interaction is validated using xenograft models, as well as distinct Kras- or Braf-driven autochthonous murine cancer models. Lastly, we show that combined checkpoint inhibition induces apoptotic cell death in KRAS- or BRAF-mutant tumor cells directly isolated from patients. These results strongly recommend simultaneous Chk1- and MK2 inhibition as a therapeutic strategy for the treatment of KRAS- or BRAF-driven cancers.