The axon guidance cue SEMA3A promotes the aggressive phenotype of basal-like PDAC

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease with few available therapeutic options. Two transcriptional cancer cell states have been consistently reported in PDAC, with the basal-like/squamous phenotype displaying a more aggressive biological behavior. Genetic and epigenetic dysregulation of the axon guidance pathway are common in PDAC, yet our understanding of its biological relevance is limited. Here, we investigated the functional role of the axon guidance cue SEMA3A in sustaining the progression of PDAC. We integrated available transcriptomic datasets of human PDAC with in situ hybridization analyses of patients' tissues to find that SEMA3A is expressed by stromal cells and selectively enriched in epithelial cells of the basal-like/squamous subtype. We found that both cell-intrinsic and cell extrinsic factors instructing the basal-like/squamous subtype induce expression of SEMA3A in PDAC cells. In vitro, SEMA3A promoted cell migration as well as anoikis resistance. At molecular level, these phenotypes were associated with increased FAK signaling and enrichment of gene programs related to cytoskeleton remodeling. Accordingly, SEMA3A provided mouse PDAC cells with greater metastatic competence. In mouse orthotopic allografts, SEMA3A remodeled the TME by favoring infiltration of tumor-associated macrophages and exclusion of T cells. Mechanistically, SEMA3A functioned as chemoattractant for macrophages and favored their polarization towards an M2-like phenotype. In SEMA3Ahigh tumors, depletion of macrophages resulted in greater intratumor infiltration by CD8+ T cells and increased sensitivity of these tumors to chemotherapy. Overall, we show that SEMA3A contributes to the malignant phenotype of basal-like PDAC.

Differential Activity of MAPK signalling Defines Fibroblast Subtypes in Pancreatic Cancer

“…To gain further insights into this CAF phenotype, we leveraged scRNA-seq data obtained from mouse tumour tissues following short-term perturbation of the MAPK pathway. Our model aligned with the human basallike/squamous PDAC 42 and showed rapid kinetics of pathway rewiring in the stromal compartment following treatment. Short-term perturbations are often used to capture primary transcriptional response to a specific stimulus 49 .…”

“…2a ). First, we generated and characterized a mouse model based on the orthotopic transplantation of a quasi-mesenchymal KPC (Kras G12D/+ ; p53 R172H/+ ; Pdx1-Cre) 41 derived cell line that in vivo produces cancer tissues aligning with the human basal-like PDAC phenotype 42 . Tumour-bearing mice treated daily with 1 mg/kg of MEKi showed reduced activation of MAPK signalling ( Supplementary Fig.…”

“…Isograft models were generated with KPC and CKP-derived cell lines. For the generation of isograft based on KPC-derived cell line (FC1199), 2.5x10 5 cells were transplanted in B6J mice as previously described 42 . For the generation of isograft based on CKP-derived cell lines (60400 and 110299), 5.0x10 5 cells were resuspended in 30 µL of a 1:1 dilution of Matrigel® (Corning) and cold plain medium and injected into the pancreas of B6J mice using insulin syringes (BD micro-fine 30 Gauge) under the guidance of Ultrasonic imaging.…”

Tumor- and Nerve-Derived Axon Guidance Molecule Promotes Pancreatic Ductal Adenocarcinoma Progression and Metastasis through Macrophage Reprogramming

“…For the first time, SEMA3D is also shown to induce lactate production and subsequent macrophage reprogramming in a mutated KRAS-dependent manner. Our study also shows a normal function of axon guidance molecules in the nerves, and not just their atopic expression in cancer cells [13][14][15]19,20,[48][49][50] , can contribute to cancer progression and metastasis through an oncogenic KRAS-ARF6 pathway. Together, our work demonstrates how inflammatory responses in the TME promote PanIN and invasive PDA progression and metastasis driven by an oncogenic process (see proposed model in Figure 8).…”

“…These proteins comprise several families, including semaphorins and their plexin receptors, which have been found to exhibit elevated expression in the TME of several cancer types, including PDA, and to promote disease progression 10,[13][14][15][16] . Axon guidance proteins have also been found to play a critical role in communication between several cell types in the PDA TME through induction of signaling cascades between epithelial cells, neurons, fibroblasts, and macrophages [17][18][19][20] . Our previous analysis of signaling pathways regulated by Annexin A2, a PDA-associated tumor antigen and metastasis-related protein, identifies the secreted protein Semaphorin 3D (SEMA3D) and its co-receptors, Plexin D1 (PLXND1) and neuropilin-1, as being involved in increasing nerve migration and PDA cell invasiveness through both autocrine and paracrine signaling to promote PDA progression and metastasis 10,15,21,22 .…”