Project Details
Projekt
Epigenetic regulation and therapeutic targeting of PDAC subtypes with aberrant drug metabolism
Applicant
Professor Dr. Albrecht Neesse
Subject Area
Gastroenterology
Term
since 2020
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 426671079
Chemoresistance constitutes a major cause for the dismal prognosis of PDAC patients. The antimetabolite gemcitabine is integral part of several currently used chemotherapeutic regimen for the treatment of PDAC patients. However, despite reasonable efficacy in vitro, gemcitabine is hardly effective in vivo and fails to prolong survival of patients as monotherapy. Increasing evidence suggests that gemcitabine inactivating enzymes rather than transport proteins determine therapeutic efficacy. Indeed, we have recently discovered upregulation of gemcitabine inactivating cytosolic 5'-nucleotidase 1A (NT5C1A) and cytidine deaminase (CDA) in PDAC tissues of about 20% of patients. Upregulation was associated with increased resistance towards gemcitabine in vitro. Thus, tumors with high expression of drug metabolizing enzymes (DME) such as NT5C1A and CDA may represent a clinically highly relevant molecular subtype of PDAC patients that could be exploited for tailored treatment approaches. Preliminary results suggest epigenetic regulation of DMEs in PDAC that might constitute a vantage point for future therapeutic approaches. Here, we aim to investigate the expression, epigenetic regulation, and therapeutic potential of drug metabolizing enzymes (DME) to tackle metabolic vulnerabilities of drug resistance in PDAC. DMEhigh and DMElow PDAC subtypes will be determined by combined detection of strong CDA and NT5C1A expression by immunohistochemistry and analyzed with regard to clinical outcome, and established higher order molecular subgroups such as the classical or quasi-mesenchymal subtype. In addition, we will determine whether activation of DMEs interferes with DNA replication by DNA fiber assays, incorporation of DNA labels and detection of single DNA tracks. Using a set of highly resistant PDX-derived primary PDAC cells we aim to identify chromatin regulatory proteins on subtype-specific DME transcription using various approaches such as siRNA libraries featuring epigenetic regulators, single ChIP assays and genetic knock-out strategies. Relevant chromatin regulatory proteins will we targeted by selected pharmacological inhibitors in combination with gemcitabine using an established preclinical in vitro platform. Furthermore, orthotopic transplantation of highly resistant PDX-derived primary PDAC cells as well as DMEhigh and DMElow PDX tumors will be employed to test therapeutic strategies using novel combinations of epigenetic inhibitors and gemcitabine + nab-paclitaxel in a standardized preclinical trial design including small animal imaging approaches such as high-resolution ultrasound. In summary, we aim to identify a novel molecular subgroup of PDAC patients that is characterized by highly dysregulated DME that are transcriptionally regulated and could be potentially targeted by epigenetic approaches to sensitize PDAC cells to standard of care chemotherapies.
DFG Programme
Clinical Research Units
