Abstract 4460: Investigating a non-canonical role for SHP2 in pancreatic ductal adenocarcinoma metabolism and response to dietary modifications
Authors: Walsh R. McKinnon , Jack Jarrid L. , Eades Austin E. , Bye Bailey A. , Ruckert Mariana T. , Ambrose Joseph , VanSaun Michael N. 
Published: March 2024

Abstract
Pancreatic ductal adenocarcinoma (PDAC) is predicted to be the second leading cause of cancer death in the US by 2025, with rising incidence. Mutant KRAS in &gt;90% of PDAC cases promotes activation of the MAPK pathway, yet targeting the MAPK pathway clinically has failed to improve patient outcomes. SHP2 canonically promotes KRAS activation and is essential for PDAC development in mouse models. Because targeting MAPK is insufficient, yet SHP2 loss blocks PDAC development, we hypothesized SHP2 has both MAPK dependent and independent functions. Initial studies revealed that SHP2 inhibition with SHP099 in murine KPC [K8484: KRASG12D/+, p53R172H/+, Pdx1Cre/+] cells required concentrations exceeding 50 μM to elicit a minimal ERK inhibition. This led us to predict that there may be a tumor suppressive mechanism of SHP2 inhibition that is KRAS/MAPK independent. We utilized available RNAseq data (NCBI GEO: PRJNA558508) of PDAC MiaPaCa2 cells treated with the MEK inhibitor, Trametinib, or SHP099 to compare the direct effects of inhibition on transcriptional outcomes. We identified inositol phosphate signaling as a candidate target, whose downstream consequence is Ca2+ flux. We measured IL-1β induced Ca2+ flux in a panel of human PDAC cells exposed to MEK or SHP2 inhibition. Trametinib treated cells showed no effect on Ca2+ flux, however, SHP099 led to a drastic depletion of free Ca2+ and response to stimulus. We then validated the Ca2+ response to IL-1β stimulus in Crispr-Cas9 SHP2-knockout K8484 cells. While we did not observe a difference in basal free calcium, we still found a reduction in response to IL-1β stimulus. Because Ca2+ is an important co-factor for mitochondrial metabolism, we then interrogated metabolic effects. We tested mitochondrial function using a Seahorse Mito-Stress test and found that while MEK inhibition failed to affect mitochondrial metabolism, SHP2 inhibition ablated it. A Glycolysis-Stress Test revealed that SHP2 inhibition led to glucose consumption primarily through anaerobic respiration. TMT-labeled phospho-proteomic analysis comparing SHP2KO and MEK inhibited K8484s revealed SHP2 dependent deficiencies in mitochondrial proteins, among others, involved in mitochondrial fission and lipid metabolism. Western diets have been shown to promote tumor progression in GEM models of PDAC, so we used KRASG12D/+, SHP2fl/fl or wt./wt, Ptf1aCre/+ (SKC and KC) mice to demonstrate that while diet-induced obesity affects KC tumor burden, the lack of SHP2 in SKCs prevents the diet associated discrepancy in tumor progression. Collectively, these data led us to conclude that while SHP2 has been studied as a contributor to KRAS signaling in PDAC, the outcomes of its role specifically on mitochondrial metabolism have yet to be appreciated or thoroughly investigated, opening the path for a new approach to its contribution to tumor progression.
Citation Format: R. McKinnon Walsh, Jarrid L. Jack, Austin E. Eades, Bailey A. Bye, Mariana T. Ruckert, Joseph Ambrose, Michael N. VanSaun. Investigating a non-canonical role for SHP2 in pancreatic ductal adenocarcinoma metabolism and response to dietary modifications [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4460.