Mutations in G protein beta subunits promote transformation and kinase inhibitor resistance.

Activating mutations of G protein alpha subunits (Ga) occur in 4-5% of all human cancers1 but oncogenic alterations in beta subunits (Gb) have not been defined. Here we demonstrate that recurrent mutations in the Gb proteins GNB1 and GNB2 confer cytokine-independent growth and activate canonical G protein signaling. Multiple mutations in GNB1 affect the protein interface that binds Ga subunits as well as downstream effectors, and disrupt Ga-Gbg interactions. Different mutations in Gb proteins clustered to some extent based on lineage; for example, all eleven GNB1 K57 mutations were in myeloid neoplasms while 6 of 7 GNB1 I80 mutations were in B cell neoplasms. Expression of patient-derived GNB1 alleles in Cdkn2a-deficient bone marrow followed by transplantation resulted in either myeloid or B cell malignancies. In vivo treatment with the dual PI3K/mTOR inhibitor BEZ235 suppressed GNB1-induced signaling and markedly increased survival. In several human tumors, GNB1 mutations co-occurred with oncogenic kinase alterations, including BCR/ABL, JAK2 V617F and BRAF V600K. Co-expression of patient-derived GNB1 alleles with these mutant kinases resulted in inhibitor resistance in each context. Thus, GNB1 and GNB2 mutations confer transformed and resistance phenotypes across a range of human tumors and may be targetable with inhibitors of G protein signaling.

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Yoda A, Adelmant G, Tamburini J, Chapuy B, Shindoh N, Yoda Y, Weigert O, Kopp N, Wu SC, Kim SS, Liu H, Tivey T, Christie AL, Elpek KG, Card J, Gritsman K, Gotlib J, Deininger MW, Makishima H, Turley SJ, Javidi-Sharifi N, Maciejewski JP, Jaiswal S, Ebert BL, Rodig SJ, Tyner JW, Marto JA, Weinstock DM, Lane AA