Exploring the role of DYRK1A in the pancreatic ductal adenocarcinoma tumour microenvironment and its potential as a therapeutic target

Abstract

[eng] Pancreatic ductal adenocarcinoma (PDAC) is known for its poor prognosis, with mortality rates that almost equal its incidence. Surgery is currently the only potentially curative option, but less than 20% of patients are eligible for resection at diagnosis, with systemic chemotherapy being the standard treatment for both resectable and metastatic disease. Despite modest improvements in survival with newer drug combinations, the aggressive nature of PDAC demands more effective therapies. One of the most challenging features of PDAC is its tumour microenvironment (TME), which can constitute up to 90% of the tumour volume. This TME is abundant in extracellular matrix (ECM) and includes cancer-associated fibroblasts (CAFs), which contribute to tumour progression by releasing growth factors, inflammatory ligands and ECM proteins that promote cancer cell proliferation, invasion, therapy resistance, and immune exclusion. However, therapeutic targeting of CAFs has been controversial, as their total depletion or inhibition can accelerate cancer progression. Recent research has revealed significant CAF heterogeneity, emphasising the need to consider their functional diversity in developing new therapeutic strategies. The dual-specificity tyrosine-regulated kinase 1A (DYRK1A) plays critical roles in several cellular processes and signal transduction pathways relevant to cancer via multiple interactors and substrates. Recently, it has emerged as a key player in PDAC, where it exerts a protumourigenic role by stabilising c-MET and EGFR receptors in cancer cells. Histological evidence showing abundant DYRK1A expression in primary tumours from a cohort of PDAC patients prompted us to investigate the role of this kinase in PDAC CAFs to evaluate its potential as a therapeutic target for remodelling the tumour-promoting, immunosuppressive PDAC stroma. To identify DYRK1A-mediated functions of PDAC CAFs, we used short hairpin (shRNA)-based knockdown or small-molecule inhibitors to reduce its expression or activity and assessed changes in cell-intrinsic properties and paracrine communication. Our findings revealed that both aspects were altered by reduced DYRK1A function, leading to reduced migratory and contractile capabilities in these cells. Transcriptome profiling of shDYRK1A PDAC CAFs showed an enrichment in pathways associated with cytoskeletal regulation, suggesting a putative regulatory mechanism for those changes. Moreover, shDYRK1A CAFs presented altered paracrine communication with cancer cells, inducing less migration of PANC-1 cells and reducing organoid growth. Secretome analysis by mass spectrometry revealed several DYRK1A-dependent downregulated factors, among which CXCL12 appeared as an interesting candidate due to their described roles in immunosuppression and PDAC progression. With the aim to evaluate potential synergies between DYRK1A inhibition with chemotherapy and/or immunotherapy, we used patient-derived organoid (PDO) cultures and immunocompetent syngeneic xenograft KPC mouse models. Combining DYRK1A inhibitors and oxaliplatin led to modest synergistic effects in PDAC PDOs that were stronger in vivo. On the other hand, combination with α-PD-1 antibodies reduced immunosuppressive infiltration in the KPC xenograft model, but increased antitumour efficacy required the addition of oxaliplatin to the treatment regime.