Enhanced dependency of KRAS-mutant colorectal cancer cells on RAD51-dependent homologous recombination repair identified from genetic interactions in Saccharomyces cerevisiae.
Activating KRAS mutations drive colorectal cancer tumorigenesis and influence response to anti-EGFR-targeted therapy. Despite recent advances in understanding Ras signaling biology and the revolution in therapies for melanoma using BRAF inhibitors, no targeted agents have been effective in KRAS-mutant cancers, mainly due to activation of compensatory pathways. Here, by leveraging the largest synthetic lethal genetic interactome in yeast, we identify that KRAS-mutated colorectal cancer cells have augmented homologous recombination repair (HRR) signaling. We found that KRAS mutation resulted in slowing and stalling of the replication fork and accumulation of DNA damage. Moreover, we found that KRAS-mutant HCT116 cells have an increase in MYC-mediated RAD51 expression with a corresponding increase in RAD51 recruitment to irradiation-induced DNA double-strand breaks (DSBs) compared to genetically complemented isogenic cells. MYC depletion using RNA interference significantly reduced IR-induced RAD51 foci formation and HRR. On the contrary, overexpression of either HA-tagged wild-type (WT) MYC or phospho-mutant S62A increased RAD51 protein levels and hence IR-induced RAD51 foci. Likewise, depletion of RAD51 selectively induced apoptosis in HCT116-mutant cells by increasing DSBs. Pharmacological inhibition targeting HRR signaling combined with PARP inhibition selectivity killed KRAS-mutant cells. Interestingly, these differences were not seen in a second isogenic pair of KRAS WT and mutant cells (DLD-1), likely due to their nondependency on the KRAS mutation for survival. Our data thus highlight a possible mechanism by which KRAS-mutant-dependent cells drive HRR in vitro by upregulating MYC-RAD51 expression. These data may offer a promising therapeutic vulnerability in colorectal cancer cells harboring otherwise nondruggable KRAS mutations, which warrants further investigation in vivo.
Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia.|School of Natural Sciences, Griffith University, Nathan, Australia.
Murugan
M
Kalimutho
Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia.
Amanda L
AL
Bain
Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
Bipasha
B
Mukherjee
Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia.|School of Natural Sciences, Griffith University, Nathan, Australia.
Purba
P
Nag
Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia.
Devathri M
DM
Nanayakkara
Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia.
Sarah K
SK
Harten
Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia.
Janelle L
JL
Harris
Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia.
Goutham N
GN
Subramanian
Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia.|School of Natural Sciences, Griffith University, Nathan, Australia.
Debottam
D
Sinha
Department of Cell Biology, Faculty of Medicine, Fukuoka University, Japan.
Senji
S
Shirasawa
Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Australia.
Sriganesh
S
Srihari
Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
Sandeep
S
Burma
Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia.
Kum Kum
KK
Khanna
D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology / Q000627:therapeutic use; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics*; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D066246:ErbB Receptors / Q000235:genetics; D045325:HCT116 Cells; D059765:Homologous Recombination; D006801:Humans; D009154:Mutation; D000067856:Poly(ADP-ribose) Polymerase Inhibitors / Q000494:pharmacology; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics*; D034741:RNA, Small Interfering / Q000235:genetics; D051135:Rad51 Recombinase / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics
D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; C117307:KRAS protein, human; C116115:MYCBP protein, human; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D034741:RNA, Small Interfering; D014157:Transcription Factors; C512478:EGFR protein, human; D066246:ErbB Receptors; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D016283:Proto-Oncogene Proteins p21(ras)


KRAS

; 
RAD51
; DNA damage response; colorectal cancer; homologous recombination repair; therapeutic vulnerability