Association of prevalent driver mutations with regulation of sEV-release and cargo content to modulate tumor progression, metastasis and treatment resistance of pancreatic cancer.

• Applicant: Dr. Tim Eiseler
• Subject Area: Gastroenterology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 547355601

Pancreatic ductal adenocarcinomas (PDACs) have a dismal prognosis and are characterized by early metastasis. Thus, mechanisms of metastasis need to be elucidated in detail to identify putative angles of attack for future treatment alternatives. Tumor progression and metastasis is mediated by prevalent driver mutations in KRAS, SMAD4, p16INK4 or TP53, but also by tumor cells communicating with matrix cells or distant pre-metastatic niches. A major part of this intercellular communication is facilitated by secretion of small extracellular nanovesicles (sEVs, exosomes), which transfer bioactive cargos, such as proteins, RNAs, or miRNAs to recipient cells, modifying their behavior. We have recently identified a driver of organotropic lung metastasis in PDAC. Organ-specific metastasis is regulated by distinct integrin (ITG) patterns on the surface of sEVs. Our preliminary data now suggest that TP53 gain-of-function alleles, like TP53R175H mediate changes in sEV cargo associated with liver metastasis, a major site of PDAC dissemination. Thus, we hypothesize that prevalent PDAC driver mutations can substantially impact on the secretion or sEV cargo profile to alter tumor progression and metastasis, which may pinpoint putative novel targets for therapeutic intervention. The objective of this proposal is to systematically identify quantitative and qualitative changes in sEVs secretion caused by prevalent PDAC driver mutations and evaluate their impact on PDAC growth, tumor progression, metastasis, immune suppression or chemoresistance. We propose the following specific aims: Aim1: Identify quantitative and qualitative changes in sEV secretion downstream of the most abundant PDAC mutational drivers. Altered sEV secretion will be evaluated using MISEV criteria. We will use engineered PDAC cell lines, mass spectrometry and miRNA microarrays to determine changes in major sEV cargos by KRAS, SMAD4, p16INK4 and TP53 variants. Aim2: Investigate if the respective altered sEV cargos are implicated in the regulation of PDAC progression and metastasis. After modulating expression of specific cargos, we will isolate sEVs from the engineered cells with driver mutations and investigate their role in proliferation, stemness, EMT, fibrosis as well as formation of pre-metastatic niches. Aim3: Determine the role of altered sEV cargos in regulating the PDAC immune-suppressive TME and chemotherapy resistance. We will use PDOs and PDO (co)-cultures to investigate regulation of PDAC immunosuppressive features, e.g., for T-cells, by altered sEV cargos as well as investigate regulation of chemotherapy resistance by pharmakotyping.

• DFG Programme: Research Grants