Deregulation of Sulfatide Synthesis in the Development and Progression of Pancreatic Cancer Precursor Lesions

Project Summary The existence of asymptomatic precursor lesions that are known to predate invasive pancreatic ductal adenocarcinoma (PDAC) by years provides a compelling “window of opportunity” for cancer interception efforts. One such precursor is intraductal papillary mucinous neoplasm (IPMN). Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS) imaging of metabolites in tissue sections from resected patient IPMN cases and from a KrasG12D/GnasR201C mouse model of IPMN, we have made a discovery in identifying long chain hydroxylated sulfatide species that are selectively enriched in IPMN. Targeting of sulfatide metabolism via small molecule inhibition of ceramide galactosyltransferase (UGT8), a key enzyme in the synthesis of the sulfatide precursor galactosylceramide, suppressed sulfatide synthesis and induced ceramide-mediated compensatory mitophagy, and subsequent apoptosis in Kras;Gnas IPMN cells and suppressed tumor growth in an allograft mouse model of IPMN. The primary objectives of this proposal are to 1) define the biological role(s) of sulfatide in the development and progression of pancreatic cancer precursor lesions, 2) test whether small molecule inhibition of sulfatide metabolism is a viable cancer interception strategy, and 3) conduct a ‘proof-of-concept’ study that MALDI-MS imaging-based assessment of sulfatides can identify positive margins and malignant nodules in challenging intraoperative frozen tissues from PDAC surgical resections. In Aim 1A, we will use an unique cohort of patient-derived organoids (PDOs) established from resected IPMN samples as well as murine-derived organoids (MDOs) and cell lines derived from Kras;Gnas mice. Using CRISPR/Cas9 technology, we will establish UGT8-/-, galactose-3-O-sulfotransferase (Gal3St1-/-), and double UGT8-/-/Gal3St1-/- knockouts to define the cell autonomous effects of sulfatide and sulfatide precursors on mitochondria lipid composition, function, dynamics, and quality control. Findings will be further integrated with transcriptomics, proteomics, and metabolomics data. In Aim 1B, we will investigate the role(s) of sulfatide in promoting the initiation and progression of pancreatic precursor lesions and evaluate its impact on the nascent tumor microenvironment and immunophenotype using orthotopic mouse models of parental and isogenic (e.g. UGT8 KO) model systems established in Aim 1A. To assess for clinical potential, in Aim 2, we will test whether targeting of sulfatide metabolism using an selective small molecule inhibitor of UGT8 attenuates the development of precursor lesions and invasive carcinoma in Kras;Gnas mice. Given the observed specificity of sulfatide to pancreatic precursor lesions and carcinomas, in Aim 3, we will collect intraoperative surgical margins and suspicious metastatic nodules from patients undergoing PDAC surgical resections at MD Anderson Cancer Center, and we will test the extent to which MALDI-MS imaging of sulfatides can identify involvement by cancer cells. Potential findings from our studies may lead to cancer interception strategies and imaging-based diagnostic applications for PDAC.