Figure S8: Acquired resistance to the combination of LB-100 and adavosertib suppressed malignant traits in CRC models (A) IncuCyte-based proliferation assays from HT-29 and SW-480 parental and resistant cells in the absence or presence of the combination (LB-100 4 µM + adavosertib 400 nM). (B) Chromosome counting and representative chromosome spreads from HT-29 and SW-480 parental and resistant cells. Nocodazole was added for 3h to block cells in mitosis. Cells were harvested by mitotic shake-off for spreading. Over 40 (HT-29 and HT-29-R) or 50 (SW-480 and SW-480-R) spreads were counted per cell line. Asterisks indicate significance level (**** p-value <0.0001) by two-tailed Mann-Whitney test. (C) Heatmaps showing the marker genes of each cluster from the scRNAseq analyses of HT-29 and SW-480 cells
Funding
Sao Paolo Research Foundation
Shanghai Academic/Technology Research Leader
Instituto de Salud Carlos III
CERCA Program/Generalitat de Catalunya
São Paulo State Foundation-FAPESP: CeTICS-Grant
European Research Council (ERC)
Instituto de Salud Carlos III (ISCIII)
National Natural Science Foundation of China (NSFC)
ARTICLE ABSTRACT
Cancer homeostasis depends on a balance between activated oncogenic pathways driving tumorigenesis and engagement of stress response programs that counteract the inherent toxicity of such aberrant signaling. Although inhibition of oncogenic signaling pathways has been explored extensively, there is increasing evidence that overactivation of the same pathways can also disrupt cancer homeostasis and cause lethality. We show here that inhibition of protein phosphatase 2A (PP2A) hyperactivates multiple oncogenic pathways and engages stress responses in colon cancer cells. Genetic and compound screens identify combined inhibition of PP2A and WEE1 as synergistic in multiple cancer models by collapsing DNA replication and triggering premature mitosis followed by cell death. This combination also suppressed the growth of patient-derived tumors in vivo. Remarkably, acquired resistance to this drug combination suppressed the ability of colon cancer cells to form tumors in vivo. Our data suggest that paradoxical activation of oncogenic signaling can result in tumor-suppressive resistance.Significance: A therapy consisting of deliberate hyperactivation of oncogenic signaling combined with perturbation of the stress responses that result from this is very effective in animal models of colon cancer. Resistance to this therapy is associated with loss of oncogenic signaling and reduced oncogenic capacity, indicative of tumor-suppressive drug resistance.
