Abstract PO-088: TRPV1+ sensory neurons provide a tumor supportive environment through recruitment of MDSCs
Authors: Restaino Anthony C. , Ahmadi Maryam , Talbot Sebastien , Vermeer Paola D. 
Published: September 2023

Abstract
Cancer neuroscience has become an increasing area of focus in cancer research as our understanding of the presence and function of intra-tumoral neurons continues to emerge, with studies indicating that tumor infiltrating neurons impact components of the tumor microenvironment promoting cancer initiation and progression. We have previously published that head and neck squamous cell carcinomas are innervated. We now focus on defining the contributions of intra-tumoral neurons to disease progression in HNSCC. Tumor implantation in a double transgenic mouse (TRPV1cre::DTAfl/wt) lacking the cancer-recruited TRPV1-expressing sensory neurons allows us to study the consequences of this neuronal loss on the local immune response. Importantly, comparison between wild type and TRPV1cre::DTAfl/wt mice demonstrated no significant immune population differences at baseline. Thus, wildtype and TRPV1cre::DTAfl/wt mice were orthotopically implanted with tumor and tumoral immune cell populations identified by flow cytometry. Cytokine and peptide concentrations were measured by ELISA. In vitro assays were preformed to molecularly define the neuronal signals and immune responses. Here, co-culture experiments of immortalized head and neck cancer cell lines and dorsal root ganglia (DRG) from wildtype mice were used to model tumor innervation in vitro. The media generated was applied to bone marrow derived (BMD) immune cells and the impact on immune cell phenotypes assayed by flow cytometry. Our orthotopic model demonstrates that the presence of HNSCC promotes a nerve-injury phenotype in ipsilateral trigeminal ganglion, demonstrated by increased expression of activating transcription factor 3 (ATF3). Utilizing a 12-color flow cytometry panel we show that tumors from TRPV1cre::DTAfl/wt mice harbor a significantly smaller population of myeloid derived suppressor cells (MDSCs) compared to those from wildtype animals. Further analysis demonstrates this population shift occurs primarily due to a decrease in the CD11b+ Ly6G+/Ly6Clo population. In vitro studies using BMD immune cells show that tumor cell-DRG co-culture conditioned media induces an expansion of the MDSC population compared to condition media from DRG or tumor cells alone. Additionally, transwell migration assays show that co-culture condition media also increases cellular migration compared to condition media from DRG or tumor cells alone. Moreover, ELISA analysis indicates that co-culture of tumor cells and DRG increases neuronal release of the neuropeptide, Substance P (SP), potentiating IL-6 release from tumor cells. In summary, we identified several mechanisms by which TRPV1-expressing intra-tumoral neurons promote MDSC infiltration at the tumor bed and promote disease progression. These mechanisms define targets for therapeutic intervention including SP and IL-6 signaling. Future studies will test the clinical utility of these targets. Together, our data suggests that intra-tumoral neurons contribute to cancer progression through generation of a tumor supportive microenvironment.
Citation Format: Anthony C. Restaino, Maryam Ahmadi, Sebastien Talbot, Paola D. Vermeer. TRPV1+ sensory neurons provide a tumor supportive environment through recruitment of MDSCs [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Innovating through Basic, Clinical, and Translational Research; 2023 Jul 7-8; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2023;29(18_Suppl):Abstract nr PO-088.