Treatment strategies targeting tumor-associated macrophages (TAMs) have been proposed in cancer areas. The functional alterations of macrophages in the microenvironment during the tumorigenesis of human epithelial cancer remain poorly understood. Here, we explored phenotypic alteration of macrophages during the development of oral squamous cell carcinoma (OSCC). Conditioned media (CM) and exosome supernatants were harvested from normal oral epithelium, oral leukoplakia cells and OSCC cells. We measured phenotypic alteration of macrophages using flow cytometry, luminex assays, and quantitative real-time PCR assay. Intracellular signaling pathway analysis, mass spectrometry proteomics, western blotting, enzyme-linked immunosorbent assay, immunohistochemical staining, and bioinformatics analysis were performed to uncover the underlying mechanisms. THP-1-derived and PBMCs derived macrophages exhibited an M1-like phenotype but not M2-like phenotype, when treated with CM from OSCC cells but not with the CM from normal epithelium or leukoplakia cells. Further investigations revealed that macrophages were activated by taking up exosomes released from OSCC cells through p38, Akt, and SAPK/JNK signaling at the early phase. We further provided evidences that THBS1 derived from OSCC exosomes participated in the polarization of macrophages to an M1-like phenotype. Reciprocally, CM from exosomes induced M1-like TAMs and significantly promoted migration of OSCC cells. We proposed a novel paracrine loop between cancer cells and macrophages based on exosomes from OSCC. Therefore, target management of M1-like TAMs polarized by exosomes shows great potential as a therapeutic target for the control of cancerous migration in OSCC.

Background: Tumor-associated macrophages (TAMs) have a leading position in the tumor microenvironment. Previously, we have demonstrated that M1-like TAMs activated by exosome-transferred THBS1 promote malignant migration in oral squamous cell carcinoma (OSCC). However, the functional roles and associated molecular mechanisms of the activated M1-like TAMs need to be further clarified in OSCC. Methods: Conditioned Media (CM) were harvested from the exosome activated M1-like TAMs. We measured the malignant behaviors of OSCC under the treatment of CM from M1-like TAMs by performing colony forming assays, invasion assays, wound-healing assays, spheroid forming assays and in vivo xenograft experiments. The underlying mechanisms were investigated by RNA-seq, cytokines analysis, intracellular signaling pathway analysis, ChIP assays, bioinformatics analysis and validation. Results: M1-like TAMs significantly promoted the epithelial-mesenchymal transition (EMT) process, and induced the cancer-stem like cells (CSCs) by upregulating the expression of MME and MMP14 in OSCC cells. Cytokine analysis revealed a shark increase of IL6 secretion from M1-like TAMs. Blocking IL6 in the CM from M1-like TAMs could significantly weaken its effects on the colony forming, invasion, migration, microsphere forming and xenograft forming abilities of OSCC cells. Cellular signaling assays indicated the activation of Jak/Stat3 pathway in the OSCC cells treated by the CM from M1-like TAMs. Blocking the activation of the Jak/Stat3 pathway could significantly weaken the effects of M1-like TAMs on the colony forming, invasion, migration, microsphere forming and xenograft forming abilities of OSCC cells. Further RNA-seq analysis and bioinformatics analysis revealed an increased expression of THBS1 in the OSCC cells treated by M1-like TAMs. Bioinformatics prediction and ChIP assays revealed the activation of Stat3 by CM from M1-like TAMs could directly promote the transcription of THBS1 in OSCC cells. Conclusions: We proposed that M1-like TAMs could cascade a mesenchymal/stem-like phenotype of OSCC via the IL6/Stat3/THBS1 feedback loop. A better understanding on the functional roles and associated molecular mechanisms of M1-like TAMs might facilitate the development of novel therapies for supplementing the current treatment strategies for OSCC patients.

Induction chemotherapy in oral squamous cell carcinoma is a controversial issue in clinical practice. To investigate the evolution of cancer cells and tumor microenvironment (TME) response to chemotherapy in oral squamous cell carcinoma, single-cell transcriptome analysis was performed in a post-chemotherapy squamous cell carcinoma located in oral cavity. The main cell types were identified based on gene expression patterns determined using dimensionality reduction and unsupervised cell clustering. Non-negative matrix factorization clustering of the gene expression of Cancer-associated fibroblasts (CAFs) and macrophages was performed. Kyoto Encyclopedia of Genes and Genomes pathway analyses and gene set enrichment analysis were performed to explore significant functional pathways. CellPhoneDB and NicheNet were used to detect the intercellular communication between cell types. CAFs were divided into “inflammatory CAFs,” “antigen-presenting CAFs” and “myofibroblastic CAFs.” Three classic subgroups of tumor-associated macrophages (TAMs) were detected, namely C1Q (+), FCN1 (+) and SPP1(+) TAMs. The inflammatory cytokine expression is elevated, and several molecular pathways, such as PI3K/Akt/mTORC1, TNF-α via NFκB, TGF-β, IL-6/JAK2/STAT3 and CXCL12/CXCR4 axis associated with epithelial-mesenchymal transition were enriched in TME. Also, CD74-MIF/COPA/APP interactions were expressed in TME of oral squamous cell carcinoma after chemotherapy. The results revealed the characteristics of TME in post-chemotherapy oral squamous cell carcinoma at single-cell transcriptome level, providing new insights and clues for further investigation.

Tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) widely participate in the malignant progression in cancer. Previously, we have demonstrated that M1-like TAMs cascaded a stem-like phenotype of oral squamous cell carcinoma (OSCC). Yet, the underlying mechanisms still need to be demonstrated for the regulation of TAMs on cancer stem cells (CSCs) in OSCC. In this study, we investigated a group of CSCs with increased expression of cluster differentiation 10 (CD10), which acted as a mediator in the interaction network between TAMs and tumor-associated neutrophils (TANs) in OSCC. The results showed a significant association between TAMs infiltrations and increased expression of CD10 among all the CSCs-related molecules in OSCC. Then, we validated that OSCC cells with high CD10 expression possessed increased CSCs characteristics. TAMs could drive the heterogenetic CD10^High CSCs by activating the IL6/STAT3/CD10 pathway. Furthermore, CD10^High CSCs could recruit and reprogram tumor-associated neutrophils (TANs) in an immunosuppressive state by secreting S100A8/A9 in OSCC. These finding indicated that CD10^High CSCs played great roles in signaling crosstalk between TAMs and TANs in OSCC, by which infiltrated TAMs drive CD 10^High CSCs to recruit and reprogram TANs in an immunosuppressive state. Herein, we managed to demonstrate that TAMs could directly regulate a heterogenetic cluster of CSCs with high CD10 expression, and CD10^High CSCs could recruit and reprogram TANs in OSCC. The novel crosstalk among OSCC-TAMs-CD10^High CSCs-TANs might bring new prospects for improving the treatment strategies for OSCC patients.

Background: Immunotherapy strategies are successful in only a subset of patients with advanced head and neck squamous cell carcinoma (HNSCC). The roles of tumor-infiltrating lymphocytes (TILs) in HNSCC are less clear. Herein, we present a preliminary study to identify the underlying heterogeneity and correlations among TILs in HNSCC by bioinformatics analysis of TIL-related biomarkers. Methods: The expression patterns, clinicopathological values and underlying correlations for the TILs related genes were analyzed based on the TCGA primary HNSCC cohort. The prognostic significance for the involved genes in the HNSCC patients was evaluated by using an online tool, Kaplan-Meier Plotter. Bioinformatics prediction for the co-expression, physical interactions, pathway, and genetic interactions of the involved genes was performed by using GeneMANIA. Results: The expression of programmed death-ligand 1 (PD-L1) was significantly correlated with the expression of CD4 (P<0.01), CD8 (P<0.01), and CD20 (P=0.011), but not CD56 (P=0.065) based on the TCGA primary HNSCC cohort. For the expression of programmed cell death 1 (PD-1), a significant correlation was also observed with the expression of CD4 (P<0.01), CD8 (P<0.01), and CD20 (P<0.01), but not CD56 (P=0.861). For the clinically significant evaluation, variable roles for the biomarkers were compared and demonstrated. Increased expression of CD8 (P=0.029), CD20 (P<0.01), or PD-1 (P=0.0084) significantly correlated with improved overall survival (OS), and increased CD56 expression indicated obviously decreased OS for HNSCC patients (P=0.0033). Significantly positive correlations between human papilloma virus (HPV) status and the expression of CD8 (P<0.01), CD20 (P<0.01) and PD-1 (P<0.01) were demonstrated and a significantly negative correlation between HPV status and CD56 expression was also demonstrated (P<0.01). In addition, IL2RB was determined to be a hub factor that regulates the infiltration of TILs and the expression of PD-1/PD-L1 in HNSCC. Conclusions: A systematic evaluation for the TILs status can be informative to predict prognosis and direct the immunotherapy for HNSCC patients, but further investigations are still needed.