Myeloid-derived suppressive cells (MDSCs) inhibit antitumor immunity and confer a survival advantage for tumor evasion. Tumor cells also support MDSC expansion and recruitment by secreting multiple growth factors and cytokines, but the mechanisms by which tumors affect MDSC function are not completely understood. Here, we found that the neuronal guidance protein netrin-1 was selectively secreted by MC38 murine colon cancer cells, which could enhance the immunosuppressive activity of MDSCs. MDSCs predominantly expressed one type of netrin-1 receptor, adenosine receptor 2B (A2BR). Netrin-1 interacted with A2BR on MDSCs to activate the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling pathway, which ultimately increased CREB phosphorylation in MDSCs. Furthermore, netrin-1 knockdown in tumor cells inhibited the immunosuppressive activity of MDSCs and restored antitumor immunity in MC38 tumor xenograft mice. Intriguingly, high netrin-1 in the plasma correlated with MDSCs in CRC patients. In conclusion, netrin-1 significantly enhanced the immunosuppressive function of MDSCs through A2BR on MDSCs, thus promoting the development of tumors. These findings highlight that netrin-1 may regulate the abnormal immune response in colorectal cancer and may become a potential target for immunotherapy.

Chronic inflammation of the alveolar bones and connective tissues supporting teeth causes periodontal disease, one of the most prevalent infectious diseases in humans. It was previously reported that oral cancer was the sixth most common cancer in the world, followed by squamous cell carcinoma. Periodontal disease has been linked to an increased risk for oral cancer in some studies, and these studies have found a positive relationship between oral cancer and periodontal disease. In this work, we aimed to explore the potential correlation between oral squamous cell carcinoma (OSCC) and Periodontal disease. The single-cell RNA sequence analysis was applied to explore the genes that were closely associated with cancer-associated fibroblasts (CAFs). the head and neck squamous cell carcinoma. The Single sample Gene Set Enrichment Analysis (ssGSEA) algorithm was applied to explore the scores of CAFs. Subsequently, the differentially expressed analysis was applied to explore the CAFs-related genes that play a key role in the OSCC cohort. The LASSO regression analysis and the COX regression analysis were applied to construct the CAFs-based periodontal disease-related risk model. In addition, the correlation analysis was used to explore the correlation between the risk model and clinical features, immune-related cells, and immune-related genes. By using the single-cell RNA sequence analysis, we successfully obtained the biomarkers for the CAFs. Finally, we successfully obtained a six-CAFs-related genes risk model. The ROC curve and survival analysis revealed that the risk model showed good predictive value in OSCC patients. Our analysis successfully provided a new direction for the treatment and prognosis of OSCC patients.

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<div>Abstract<p>Myeloid-derived suppressive cells (MDSC) inhibit antitumor immunity and confer a survival advantage for tumor evasion. Tumor cells also support MDSC expansion and recruitment by secreting multiple growth factors and cytokines, but the mechanisms by which tumors affect MDSC function are not completely understood. Here, we found that the neuronal guidance protein netrin-1 was selectively secreted by MC38 murine colon cancer cells, which could enhance the immunosuppressive activity of MDSCs. MDSCs predominantly expressed one type of netrin-1 receptor, adenosine receptor 2B (A2BR). Netrin-1 interacted with A2BR on MDSCs to activate the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling pathway, which ultimately increased CREB phosphorylation in MDSCs. Furthermore, netrin-1 knockdown in tumor cells inhibited the immunosuppressive activity of MDSCs and restored antitumor immunity in MC38 tumor xenograft mice. Intriguingly, high netrin-1 in the plasma correlated with MDSCs in patients with colorectal cancer. In conclusion, netrin-1 significantly enhanced the immunosuppressive function of MDSCs through A2BR on MDSCs, thus promoting the development of tumors. These findings highlight that netrin-1 may regulate the abnormal immune response in colorectal cancer and may become a potential target for immunotherapy.</p></div>