Stromal cells in the tumor microenvironment promote the progression of oral squamous cell carcinoma

Areca nut-induced metabolic reprogramming and M2 differentiation promote OPMD malignant transformation

BACKGROUND

Betel quid and its major ingredient, areca nut, are recognized by IARC as major risk factors in oral cancer development. Areca nut extract (ANE) exposure has been linked to OPMD progression and malignant transformation to OSCC. However, the detailed mechanism through which ANE acts on other cell types in the oral microenvironment to promote oral carcinogenesis remains elusive.

METHODS

Immunoprofiling of macrophages associated with OPMD and OSCC was carried out by immunohistochemical and immunofluorescence staining. Phosphokinase and cytokine arrays and western blotting were performed to determine the underlying mechanisms. Transwell assays were used to evaluate the migration-promoting effect of ANE. Hamster model was finally applied to confirm the in vivo effect of ANE.

RESULTS

We reported that M2 macrophages positively correlated with oral cancer progression. ANE induced M2 macrophage differentiation, CREB phosphorylation and VCAM-1 secretion and increased mitochondrial metabolism. Conditioned medium and VCAM-1 from ANE-treated macrophages promoted migration and mesenchymal phenotypes in oral precancer cells. In vivo studies showed that ANE enhanced M2 polarization and related signaling pathways in the oral buccal tissues of hamsters.

CONCLUSION

Our study provides novel mechanisms for areca nut-induced oral carcinogenesis, demonstrating that areca nut promotes M2 macrophage differentiation and secretion of oncogenic cytokines that critically activate malignant transformation of oral premalignant cells.

Biomolecular alterations temporally anticipate microarchitectural modifications of collagen in oral tongue squamous cell carcinoma

High resolution analysis of collagen bundles could provide information on tumor onset and evolution. This study was focused on the microarchitecture and biomolecular organization of collagen bundles in oral tongue squamous cell carcinoma (OTSCC). Thirty-five OTSCC biopsy samples were analyzed by synchrotron-based phase-contrast microcomputed tomography and Fourier transform infrared imaging (FTIRI) spectroscopy. PhC-microCT evidenced the presence of reduced and disorganized collagen in the tumor area compared to the extratumoral (ExtraT) one. FTIRI also revealed a reduction of folded secondary structures in the tumor area, and highlighted differences in the peritumoral (PeriT) areas in relation with the OTSCC stage, whereby a significantly lower amount of collagen with less organized fibers was found in the PeriT stroma of advanced-OTSCC stages. Interestingly, no significant morphometrical mismatches were detected in the same region by PhC-microCT analysis. These results suggest that biomolecular alterations in the OTSCC stroma temporally anticipate structural modifications of collagen bundle microarchitecture.

Impact of histopathological parameters in prognosis of oral squamous cell carcinoma

OBJECTIVE

Squamous cell carcinomas comprise approximately 90% of all oral malignancies. There is a wide geographical variation in the incidence of oral cancer, with South and South East Asia (SSEA) accounting for almost two third of new cases. The prognosis of oral cancer is influenced by a vast array of factors including demographic, clinical, histopathological and molecular factors. The objective this review is to analyse the impact of histopathological features assessed in hematoxylin and eosin stained sections on the prognosis of OSCC.

MATERIALS AND METHODS

Medline and Scopus data base search was performed in order to identify related articles on histopathological parameters in predicting prognosis of oral squamous cell carcinoma. The primary emphasis is on the studies conducted in SSEA, with an accompanying comparison of their findings with those from research conducted in other parts of the world.

RESULTS

It has been shown that the number of studies conducted in SSEA is not proportionate to the high prevalence of Oral Cancer in the region. There is no significant difference between the findings from SSEA compared to the rest of the world. It is clearly shown that most histopathological parameters can be accurately used to predict nodal metastasis and prognosis.

CONCLUSIONS

Histopathological parameters can be used reliably in planning treatment of Oral cancer. Clinicians should combine clinical and histopathological parameters in drawing treatment plan for Oral Cancer.

Crosstalk between cancer cells and macrophages promotes OSCC cell migration and invasion through a CXCL1/EGF positive feedback loop

BACKGROUND

C-X-C motif chemokine ligand 1 (CXCL1) and epithelial growth factor (EGF) are highly secreted by oral squamous cell carcinoma (OSCC) cells and tumor-associated macrophages, respectively. Recent studies have shown that there is intricate "cross-talk" between OSCC cells and macrophages. However, the underlying mechanisms are still poorly elucidated.

METHODS

The expression of CXCL1 was detected by immunohistochemistry in OSCC clinical samples. CXCL1 levels were evaluated by RT‒PCR and ELISA in an OSCC cell line and a normal epithelial cell line. The expression of EGF was determined by RT‒PCR and ELISA. The effect of EGF on the proliferation of OSCC cells was evaluated by CCK-8 and colony formation assays. The effect of EGF on the migration and invasion ability and epithelial-mesenchymal transition (EMT) of OSCC cells was determined by wound healing, Transwell, RT‒PCR, Western blot and immunofluorescence assays. The polarization of macrophages was evaluated by RT‒PCR and flow cytometry. Western blotting was used to study the molecular mechanism in OSCC.

RESULTS

The expression of C-X-C motif chemokine ligand 1 (CXCL1) was higher in the OSCC cell line (Cal27) than in immortalized human keratinocytes (Hacat cells). CXCL1 derived from Cal27 cells upregulates the expression of epithelial growth factor (EGF) in macrophages. Paracrine stimulation mediated by EGF further facilitates the epithelial-mesenchymal transition (EMT) of Cal27 cells and initiates the upregulation of CXCL1 in a positive feedback-manner. Mechanistically, EGF signaling-induced OSCC cell invasion and migration can be ascribed to the activation of NF-κB signaling mediated by the epithelial growth factor receptor (EGFR), as determined by western blotting.

CONCLUSIONS

OSCC cell-derived CXCL1 can stimulate the M2 polarization of macrophages and the secretion of EGF. Moreover, EGF significantly activates NF-κB signaling and promotes the migration and invasion of OSCC cells in a paracrine manner. A positive feedback loop between OSCC cells and macrophages was formed, contributing to the promotion of OSCC progression.

BRG1 mediates epigenetic regulation of TNFα-induced CCL2 expression in oral tongue squamous cell carcinoma cells

Strong evidence has indicated that upregulation of chemokine (CC motif) ligand-2 (CCL2) expression and the presence of an inflammatory tumor microenvironment significantly contribute to the migratory and invasive properties of oral squamous cell carcinoma, specifically oral tongue squamous cell carcinoma (OTSCC). However, the precise epigenetic mechanism responsible for enhanced CCL2 expression in response to the inflammatory mediator tumor necrosis factor alpha (TNF-α) in OTSCC remains inadequately elucidated. We have demonstrated that the production of CCL2 can be induced by TNF-α, and this induction is mediated by the chromatin remodel protein BRG1. Through the use of a chromatin immunoprecipitation (ChIP) assay, we have found that BRG1 was involved in the recruitment of acetylated histones H3 and H4 at the CCL2 promoter, thereby activating TNF-α-induced CCL2 transcription. Furthermore, we have observed that recruitment of NF-κB p65 to the CCL2 promoter was increased following BRG1 overexpression and decreased after BRG1 knockdown in OTSCC cells. Our Re-ChIP assay has shown that BRG1 knockdown completely inhibits the recruitment of both acetylated histone H3 or H4 and NF-κB to the CCL2 promoter. In summary, the findings of our study demonstrate that BRG1 plays a significant role in mediating the production of CCL2 in OTSCC cells in response to TNF-α stimulation. This process involves the cooperative action of acetylated histone and NF-κB recruitment to the CCL2 promoter site. Our data suggest that BRG1 serves as a critical epigenetic mediator in the regulation of TNF-α-induced CCL2 transcription in OTSCC cells.

HMGB1-activated tumor-associated macrophages promote migration and invasion via NF-κB/IL-6 signaling in oral squamous cell carcinoma

Tumor-associated macrophages (TAMs) are a highly abundant cell population within the tumor microenvironment of oral squamous cell carcinomas (OSCC). Recent studies have identified an intricate cross-talk between cancer cells and macrophages in the tumor microenvironment. However, the underlying mechanism remains unclear. High-mobility group box 1 (HMGB1) was linked to metastasis and an unfavorable prognosis in head and neck squamous cell carcinoma. Furthermore, it was significantly upregulated in moderately differentiated OSCC tissues and the OSCC cell lines CAL27 and SCC9. HMGB1 knockdown impedes the ability of TAMs to induce invasion and migration of OSCC cells. Phenotypic changes in macrophages were measured after incubation of supernatant from OSCC cells transfected with HMGB1 siRNA or supplemented with recombinant HMGB1. HMGB1 induced M1 polarization of macrophages and the secretion of IL-6 via the NF-κB pathway, contributing to the OSCC malignant migration. HMGB1 originating from OSCC cells, along with its downstream signaling pathways, holds promise as a potential therapeutic target for mitigating metastasis and improving the survival rate of OSCC.

Oral tumor heterogeneity, its implications for patient monitoring and designing anti-cancer strategies

Oral cancer tumors occur in the mouth and are mainly derived from oral mucosa linings. It is one of the most common and fatal malignant diseases worldwide. The intratumor heterogeneity (ITH) of oral cancerous tumor is vast, so it is challenging to study and interpret. Due to environmental selection pressures, ITH arises through diverse genetic, epigenetic, and metabolic alterations. The ITH also talks about peri-tumoral vascular/ lymphatic growth, perineural permeation, tumor necrosis, invasion, and clonal expansion/ the coexistence of multiple subclones in a single tumor. The heterogeneity offers tumors the adaptability to survive, induce growth/ metastasis, and, most importantly, escape antitumor therapy. Unfortunately, the ITH is prioritized less in determining disease pathology than the traditional TNM classifications or tumor grade. Understanding ITH is challenging, but with the advancement of technology, this ITH can be decoded. Tumor genomics, proteomics, metabolomics, and other modern analyses can provide vast information. This information in clinics can assist in understanding a tumor's severity and be used for diagnostic, prognostic, and therapeutic decision-making. Lastly, the oral tumor ITH can lead to individualized, targeted therapy strategies fighting against OC.

SOD3 Expression in Tumor Stroma Provides the Tumor Vessel Maturity in Oral Squamous Cell Carcinoma

Tumor angiogenesis is one of the hallmarks of solid tumor development. The progressive tumor cells produce the angiogenic factors and promote tumor angiogenesis. However, how the tumor stromal cells influence tumor vascularization is still unclear. In the present study, we evaluated the effects of oral squamous cell carcinoma (OSCC) stromal cells on tumor vascularization. The tumor stromal cells were isolated from two OSCC patients with different subtypes: low invasive verrucous squamous carcinoma (VSCC) and highly invasive squamous cell carcinoma (SCC) and co-xenografted with the human OSCC cell line (HSC-2) on nude mice. In comparison, the CD34+ vessels in HSC-2+VSCC were larger than in HSC-2+SCC. Interestingly, the vessels in the HSC-2+VSCC expressed vascular endothelial cadherin (VE-cadherin), indicating well-formed vascularization. Our microarray data revealed that the expression of extracellular superoxide dismutase, SOD3 mRNA is higher in VSCC stromal cells than in SCC stromal cells. Moreover, we observed that SOD3 colocalized with VE-cadherin on endothelial cells of low invasive stroma xenograft. These data suggested that SOD3 expression in stromal cells may potentially regulate tumor vascularization in OSCC. Thus, our study suggests the potential interest in SOD3-related vascular integrity for a better OSCC therapeutic strategy.

Phenformin suppresses angiogenesis through the regulation of exosomal microRNA-1246 and microRNA-205 levels derived from oral squamous cell carcinoma cells

Exosomes secreted by cancer cells are important components in the tumor microenvironment, enabling cancer cells to communicate with each other and with noncancerous cells to play important roles in tumor progression and metastasis. Phenformin, a biguanide antidiabetic drug, has been reported to have a strong antitumor function in multiple types of cancer cells, however little research has been reported about whether phenformin can regulate the secretion of exosomes by cancer cells to regulate the tumor microenvironment and contribute to its antitumor function. Here we found that exosomes (Phen-Exo) derived from phenformin-treated oral squamous cell carcinoma (OSCC) cells significantly suppress the proliferation, migration and tube formation of human umbilical vein endothelial cells (HUVECs) in vitro. The inhibition of angiogenesis by Phen-Exo was verified in vivo by matrigel plug angiogenesis assays and by chick chorioallantoic membrane assays. Mechanistically, we discovered that the expression of microRNA-1246 (miR-1246) and microRNA-205 (miR-205) was significantly increased in exosomes secreted by OSCC cells treated with phenformin, while high expression levels of miR-1246 or miR-205 in vascular endothelial cells inhibited their angiogenic effects and decreased expression of the angiogenic factor VEGFA. In conclusion, these results reveal that phenformin can inhibit angiogenesis by regulating the levels of miR-1246 and miR-205 in exosomes secreted by OSCC cells, suggesting that phenformin has the potential to alter the tumor microenvironment to antagonize the growth of OSCCs, which provides a theoretical basis for developing new strategies to treat OSCCs in the future.

Investigation into Chronic Low-Dose Ionizing Radiation Effect on Gene Expression Profile of Human HUVECs Cells

Introduction: Understanding the molecular mechanism of chronic low-dose ionizing radiation (LDIR) effects on the human body is the subject of many research studies. Several aspects of cell function such as cell proliferation, apoptosis, inflammation, and tumorigenesis are affected by LDIR. Detection of the main biological process that is targeted by LIDR via network analysis is the main aim of this study. Methods: GSE66720 consisting of gene expression profiles of human umbilical vein endothelial cells (HUVECs) (a suitable cell line to be investigated), including irradiated and control cells, was downloaded from Gene Expression Omnibus (GEO). The significant differentially expressed genes (DEGs) were determined and analyzed via protein-protein interaction (PPI) network analysis to find the central individuals. The main cell function which was related to the central nodes was introduced. Results: Among 64 queried DEGs, 48 genes were recognized by the STRING database. C-X-C motif chemokine ligand 8 (CXCL8), intercellular adhesion molecule 1 (ICAM1), Melanoma growth-stimulatory activity/growth-regulated protein α (CXCL1), vascular cell adhesion molecule 1 (VCAM-1), and nerve growth factor (NGF) were introduced as hub nodes. Conclusion: Findings indicate that inflammation is the main initial target of LDIR at the cellular level which is associated with alteration in the other essential functions of the irradiated cells.

The 'Danse Macabre'-Neutrophils the Interactive Partner Affecting Oral Cancer Outcomes

Over the past few decades, tremendous advances in the prevention, diagnosis, and treatment of cancer have taken place. However for head and neck cancers, including oral cancer, the overall survival rate is below 50% and they remain the seventh most common malignancy worldwide. These cancers are, commonly, aggressive, genetically complex, and difficult to treat and the delay, which often occurs between early recognition of symptoms and diagnosis, and the start of treatment of these cancers, is associated with poor prognosis. Cancer development and progression occurs in concert with alterations in the surrounding stroma, with the immune system being an essential element in this process. Despite neutrophils having major roles in the pathology of many diseases, they were thought to have little impact on cancer development and progression. Recent studies are now challenging this notion and placing neutrophils as central interactive players with other immune and tumor cells in affecting cancer pathology. This review focuses on how neutrophils and their sub-phenotypes, N1, N2, and myeloid-derived suppressor cells, both directly and indirectly affect the anti-tumor and pro-tumor immune responses. Emphasis is placed on what is currently known about the interaction of neutrophils with myeloid innate immune cells (such as dendritic cells and macrophages), innate lymphoid cells, natural killer cells, and fibroblasts to affect the tumor microenvironment and progression of oral cancer. A better understanding of this dialog will allow for improved therapeutics that concurrently target several components of the tumor microenvironment, increasing the possibility of constructive and positive outcomes for oral cancer patients. For this review, PubMed, Web of Science, and Google Scholar were searched for manuscripts using keywords and combinations thereof of "oral cancer, OSCC, neutrophils, TANs, MDSC, immune cells, head and neck cancer, and tumor microenvironment" with a focus on publications from 2018 to 2021.

Significance of cancer stroma for bone destruction in oral squamous cell carcinoma using different cancer stroma subtypes

Stromal cells in the tumor microenvironment (TME) can regulate the progression of numerous types of cancer; however, the bone invasion of oral squamous cell carcinoma (OSCC) has been poorly investigated. In the present study, the effect of verrucous SCC-associated stromal cells (VSCC-SCs), SCC-associated stromal cells (SCC-SCs) and human dermal fibroblasts on bone resorption and the activation of HSC-3 osteoclasts in vivo were examined by hematoxylin and eosin, AE1/3 (pan-cytokeratin) and tartrate-resistant acid phosphatase staining. In addition, the expression levels of matrix metalloproteinase (MMP)9, membrane-type 1 MMP (MT1-MMP), Snail, receptor activator of NF-κB ligand (RANKL) and parathyroid hormone-related peptide (PTHrP) in the bone invasion regions of HSC-3 cells were examined by immunohistochemistry. The results suggested that both SCC-SCs and VSCC-SCs promoted bone resorption, the activation of osteoclasts, and the expression levels of MMP9, MT1-MMP, Snail, RANKL and PTHrP. However, SCC-SCs had a more prominent effect compared with VSCC-SCs. Finally, microarray data were used to predict potential genes underlying the differential effects of VSCC-SCs and SCC-SCs on bone invasion in OSCC. The results revealed that IL1B, ICAM1, FOS, CXCL12, INS and NGF may underlie these differential effects. In conclusion, both VSCC-SCs and SCC-SCs may promote bone invasion in OSCC by enhancing the expression levels of RANKL in cancer and stromal cells mediated by PTHrP; however, SCC-SCs had a more prominent effect. These findings may represent a potential regulatory mechanism underlying the bone invasion of OSCC.

Role of the Tumor Microenvironment and the Influence of Epigenetics on the Tumor Microenvironment in Oral Carcinogenesis: Potential Implications

Oral cancer has become a significant problem throughout the world, particularly in countries that are still developing. Recent literature supports the contribution of components of the tumor microenvironment (TME) and the effect of epigenetic changes happening in the cells of the TME on oral cancer development and progression. In this review, we comprehensively examine the significance of TME in the development of OC along with the current understanding of the epigenetic modifications that regulate the TME and their cohesive impact on tumor traits and their potential as therapeutic targets.

Cancer-Associated Stromal Cells Promote the Contribution of MMP2-Positive Bone Marrow-Derived Cells to Oral Squamous Cell Carcinoma Invasion

Simple Summary

Based on its invasiveness, oral squamous cell carcinoma (OSCC) shows two different subtypes: less-invasive verrucous squamous carcinoma (VSCC) or highly invasive squamous cell carcinoma (SCC). The stromal component influences OSCC progression and invasion. On the other hand, bone marrow-derived cells (BMDCs) are recruited into tumors and involved in tumor development. We hypothesized that stromal factors might also affect the relation of BMDCs and tumor invasion. We established the OSCC models transplanted with stromal cells from VSCC and SCC, and we compared the potential stromal factors of VSCC and SCC for the involvement of BMDCs in tumor invasion. Our study showed that stromal factors IL6 and IL1B might promote the contribution of MMP-2 positive BMDCs to OSCC invasion.

Abstract

Tumor stromal components contribute to tumor development and invasion. However, the role of stromal cells in the contribution of bone marrow-derived cells (BMDCs) in oral squamous cell carcinoma (OSCC) invasion is unclear. In the present study, we created two different invasive OSCC patient-derived stroma xenografts (PDSXs) and analyzed and compared the effects of stromal cells on the relation of BMDCs and tumor invasion. We isolated stromal cells from two OSCC patients: less invasive verrucous OSCC (VSCC) and highly invasive conventional OSCC (SCC) and co-xenografted with the OSCC cell line (HSC-2) on green fluorescent protein (GFP)-positive bone marrow (BM) cells transplanted mice. We traced the GFP-positive BM cells by immunohistochemistry (IHC) and detected matrix metalloproteinase 2 (MMP2) expression on BM cells by double fluorescent IHC. The results indicated that the SCC-PDSX promotes MMP2-positive BMDCs recruitment to the invasive front line of the tumor. Furthermore, microarray analysis revealed that the expressions of interleukin 6; IL-6 mRNA and interleukin 1 beta; IL1B mRNA were higher in SCC stromal cells than in VSCC stromal cells. Thus, our study first reports that IL-6 and IL1B might be the potential stromal factors promoting the contribution of MMP2-positive BMDCs to OSCC invasion.