Therapeutic vulnerabilities of mesenchymal subpopulations of pancreatic cancer cells undergoing anabolic reprogramming [set 1]

Malignant neoplasms adapt and evolve in response to changes in oncogenic signaling, tumor microenvironmental stresses,and therapeutic interventions. Cancer cell plasticity in response to these evolutionary pressures is foundational to tumor progression and maintenance and therapeutic resistance. Here, to elucidate the underlying molecular and cellularmechanisms of cancer cell plasticity, integrated system-level, functional and genetic analyses were conducted in a conditional oncogenic Kras model of pancreatic ductal adenocarcinoma (PDAC), amalignancy displaying remarkable phenotypic diversityand morphological heterogeneity. In this model, stochastic extinction of oncogenic Krassignaling and emergence ofKras-independent escaper populationsis associated withde-differentiation and aggressive biological behavior.Transcriptomic and functional analyses ofKras-independent escapers reveal mesenchymal reprogramming driven by aSmarcb1/Mycnetwork and independence from MAPK signaling.A somatic mosaic model of PDAC which can track evolving subpopulations shows that depletion of Smarcb1 activates theMyc network which results in an anabolic switch to increased protein metabolism and the adaptive activation of ERstress-induced survival pathways.Theelevated protein turnover made mesenchymal sub-populationshighly susceptible topharmacological and genetic perturbation of the cellular proteostatic machinery andthe IRE1-/MKK4 arm of the ER stress response pathway. Specifically, combination regimens impairing the unfolded protein responses (UPR) and the ER stress response can block the emergence of aggressive mesenchymal subpopulations in murine andpatient-derived PDACmodels. These molecular and biological insights inform a potential therapeutic strategy fortargeting aggressive mesenchymal features of PDAC.

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Genovese G, Carugo A, Tepper J, Robinson FS, Li L, Svelto M, Nezi L, Corti D, Minelli R, Pettazzoni P, Gutschner T, Wu CC, Seth S, Akdemir KC, Leo E, Amin S, Molin MD, Ying H, Kwong LN, Colla S, Takahashi K, Ghosh P, Giuliani V, Muller F, Dey P, Jiang S, Garvey J, Liu CG, Zhang J, Heffernan TP, Toniatti C, Fleming JB, Goggins MG, Wood LD, Sgambato A, Agaimy A, Maitra A, Roberts CW, Wang H, Viale A, DePinho RA, Draetta GF, Chin L