Abstract 80P
Background
The Kirsten rat sarcoma viral oncogene homolog (KRAS) belongs to the Ras protein family of small Guanosine-Triphosphate hydrolases (GTPases) that favors the activation of the mitogen-activated protein kinases (MAPK) pathway involved in cell survival and proliferation. KRAS mutations (mutKRAS) can initiate and maintain cancer progression, they are present in solid tumors (lung, colon and pancreas) and treatments remain difficult. The transcriptional co-activator (YAP1) and the transcription factor family Transcriptional enhanced associate domain 1-4 (TEAD1-4) are downstream effectors of the Hippo-YAP1 pathway that regulates cell proliferation, cell survival and cell migration. Several studies highlight the role of the Hippo-YAP1 pathway as bypass mechanism to MAPK pathway inactivation that leads to drug resistance. Here we investigate the effect of the dual inhibition of MAPK and Hippo-YAP1 signaling in cell lines driven by mutant KRAS.
Methods
We have looked at cell viability (CellTiter-Glo (CTG) assay), cell cycle progression (FUCCI system, FACS) and gene transcription (RNA-Seq) before and after the inhibition of either pathway alone or in combination.
Results
We observed that the dual inhibition of both pathways was beneficial for some of the tumor cell line tested. Cell lines responding to the dual inhibition of both pathways generally showed a strong cell growth inhibition effect. Mechanistically, we detected a dual cell cycle arrest at G0/G1 phase while decreasing G2/M phase (FACS analysis). These phenotypes were complemented by downregulated MYC and E2F target gene signatures (RNA-Seq) and reduced the abundance of Spindle Assembly Checkpoint (SAC) components (observed by proteomics and confirmed with capillarity).
Conclusions
In conclusion, the dual inhibition of MAPK and Hippo-YAP1 pathways can be beneficial for a subset of KRAS mutated cell lines. Further analyses will be required to better clarify the genetic and molecular context of this specific phenotypic response. Our data support the potential therapeutical impact of YAP1 inhibition for KRAS cancer patients. Key words: Hippo-YAP1, cancer resistance, mutKRAS, dual cell cycle arrest.
Legal entity responsible for the study
Sanofi.
Funding
Sanofi.
Disclosure
S.L. Tammaccaro, P. Prigent, J.C. Le Bail, O. Dos Santos, L. Dassencourt, P. Picard-Vernier, M. Eskandar, A. Buzy, J-C. Guillemot, Y. Veeranagouda, M. Didier, E. Spanakis, T. Kanno, M. Cesaroni, S. Mathieu, L. Canard, A.H. Casse, L. Debussche, J. Moll, I. Valtingojer: Financial Interests, Personal, Stocks/Shares, Sanofi's employee and/or shareholder: Sanofi.