Epigenetic regulators governing cancer stem cells and epithelial-mesenchymal transition in oral squamous cell carcinoma

About a Possible Impact of Endodontic Infections by Fusobacterium nucleatum or Porphyromonas gingivalis on Oral Carcinogenesis: A Literature Overview

Periodontitis is linked to the onset and progression of oral squamous cell carcinoma (OSCC), an epidemiologically frequent and clinically aggressive malignancy. In this context, Fusobacterium (F.) nucleatum and Porphyromonas (P.) gingivalis, two bacteria that cause periodontitis, are found in OSCC tissues as well as in oral premalignant lesions, where they exert pro-tumorigenic activities. Since the two bacteria are present also in endodontic diseases, playing a role in their pathogenesis, here we analyze the literature searching for information on the impact that endodontic infection by P. gingivalis or F. nucleatum could have on cellular and molecular events involved in oral carcinogenesis. Results from the reviewed papers indicate that infection by P. gingivalis and/or F. nucleatum triggers the production of inflammatory cytokines and growth factors in dental pulp cells or periodontal cells, affecting the survival, proliferation, invasion, and differentiation of OSCC cells. In addition, the two bacteria and the cytokines they induce halt the differentiation and stimulate the proliferation and invasion of stem cells populating the dental pulp or the periodontium. Although most of the literature confutes the possibility that bacteria-induced endodontic inflammatory diseases could impact on oral carcinogenesis, the papers we have analyzed and discussed herein recommend further investigations on this topic.

The Therapeutic Effects of Mesenchymal Stem Cells and their Secretome on Oral Squamous Cell Carcinoma

Oral cancers are prevalent in the human population, particularly in unindustrialized countries. In 90 % of oral cancers, the tumors arise from squamous cells, which is called oral squamous cell carcinoma (OSCC). Despite new treatment strategies, the morbidity and mortality rates are still high. Current treatment options including surgery, chemotherapy, and radiotherapy are not effective in the treatment of the tumor. Cell therapy with mesenchymal stem cells (MSCs) is considered one of the leading strategies in cancer treatment. However, the field of MSC therapy in OSCC is immature and ongoing studies are being conducted in experimental and pre-clinical studies. Here, we reviewed these studies to figure out whether the use of MSCs could be worthwhile in OSCC therapy or not. Both native and engineered MSCs as well as their secretome have been used in the treatment of OSCC. It seems that genetically modified MSCs or their secretome could inhibit the tumorigenesis of OSCC. However, further pre-clinical studies are required to come to a conclusion.

TAB2 Promotes the Biological Functions of Head and Neck Squamous Cell Carcinoma Cells via EMT and PI3K Pathway

Background

Transforming growth factor β₁-activated kinase 1 binding protein 2 (TAB2) mediates a variety of biological processes through activated nuclear factor κ-light-chain-enhancer of activated B cell (NF-κB) signaling pathways. TAB2 has been reported to be upregulated in a variety of tumors. However, little is known about its potential role in oral squamous cell carcinoma (OSCC). Material and Methods. Patients' clinicopathological and transcription data were obtained from The Cancer Genome Atlas (TCGA) database. Immunohistochemistry staining was used to determine TAB2 expression in OSCC tissues (IHC). The expression of TAB2 in OSCC cell lines was detected by western blotting. The CCK-8 test and flow cytometry assay were utilized to evaluate cell proliferation, apoptosis, and cell cycle in OSCC cell lines. Enrichment analysis and identification of predicted signaling pathways were performed by Gene Ontology and KEGG analysis. Finally, the expression of downstream signal molecules was performed using western blotting to validate the mechanism investigations.

Results

TAB2 expression level was aberrantly upregulated in OSCC patients. TAB2 expression was shown to be inversely associated to prognosis. The phenotypic of OSCC cells was considerably impacted by TAB2. OSCC cells with deleted TAB2 exhibit decreased proliferation and increased apoptosis. Additionally, OSCC progression is aided by TAB2 overexpression. Further mechanism studies showed that TAB2 could regulate the progression of OSCC by mediating the upregulation of EMT and PI3K-AKT signaling pathways.

Conclusion

This study sheds light on the carcinogenic role of TAB2 in OSCC and provides a potential therapeutic strategy.

Ubiquitin D Promotes Progression of Oral Squamous Cell Carcinoma via NF-Kappa B Signaling

Ubiquitin D (UBD) is highly upregulated in many cancers, and plays a pivotal role in the pathophysiological processes of cancers. However, its roles and underlying mechanisms in oral squamous cell carcinoma (OSCC) are still unclear. In the present study, we investigated the role of UBD in patients with OSCC. Quantitative real-time polymerase chain reaction and Western blot were used to measure the expression of UBD in OSCC tissues. Immunohistochemistry assay was used to detect the differential expressions of UBD in 244 OSCC patients and 32 cases of normal oral mucosae. In addition, CCK-8, colony formation, wound healing and Transwell assays were performed to evaluate the effect of UBD on the cell proliferation, migration, and invasion in OSCC. Furthermore, a xenograft tumor model was established to verify the role of UBD on tumor formation in vivo. We found that UBD was upregulated in human OSCC tissues and cell lines and was associated with clinical and pathological features of patients. Moreover, the overexpression of UBD promoted the proliferation, migration and invasion of OSCC cells; however, the knockdown of UBD exerted the opposite effects. In this study, our results also suggested that UBD promoted OSCC progression through NF-κB signaling. Our findings indicated that UBD played a critical role in OSCC and may serve as a prognostic biomarker and potential therapeutic target for OSCC treatment.

Extracellular matrix metalloproteinase inducer expression in histological grades of oral squamous cell carcinoma - An immunohistochemical study

Background:

Oral squamous cell carcinoma (OSCC) is the most common type of head-and-neck cancer. It is a complex and relentless malignancy prone to local invasion and dissemination. An insight into the molecular alterations associated with metastasis will provide critical insights into the fundamental mechanisms underlying its progression and further contribute to improvements in the clinical management of H and N cancer patients. Hence, identifying specific biomarkers would pave the way for early detection and prognosis of OSCC. Extracellular matrix metalloproteinase inducer (EMMPRIN) is a membrane-bound glycoprotein found on the surface of tumor cells. It plays a central role in the promotion of tumor invasion, progression and metastasis as it upregulates matrix metalloproteinases secreted from adjacent fibroblasts. There is a paucity of studies on the expression of EMMPRIN in OSCC.

Objectives:

The aim is to assess the immunohistochemical expression of EMMPRIN in OSCC and to compare it with the clinicopathological parameters and histological grades of OSCC.

Materials and Methods:

Thirty histopathologically diagnosed cases of OSCC were included in the study. The slides were immunohistochemically analyzed for EMMPRIN expression and correlated with the clinicopathological parameters and histological grades of OSCC.

Results:

EMMPRIN expression was noted in all 30 cases of OSCC. Strong EMMPRIN expression was noted in the advanced clinical stages of OSCC. Higher histological grades of OSCC exhibited strong EMMPRIN expression.

Conclusion:

EMMPRIN overexpression indicates that this protein could be used as an important biological prognostic marker to identify high-risk OSCC patients.

TGF-β induced EMT and stemness characteristics are associated with epigenetic regulation in lung cancer

Transforming growth factor-β (TGF-β) promotes tumor invasion and metastasis by inducing epithelial-mesenchymal transition (EMT). EMT is often related with acquisition of stemness characteristics. The objective of this study was to determine whether EMT and stemness characteristics induced by TGF-β might be associated with epigenetic regulation in lung cancer. A human normal lung epithelial cell line and four lung cancer cell lines were treated with TGF-β. Transcriptome analysis of BEAS-2B and A549 cells incubated with TGF-β were analyzed through next-generation sequencing (NGS). Western blotting was carried out to investigate expression levels of epithelial and mesenchymal markers. Wound healing and Matrigel invasion assay, sphere formation assay, and in vivo mice tumor model were performed to evaluate functional characteristics of EMT and stemness acquisition. To investigate whether activation of EMT and stem cell markers might be involved in epigenetic regulation of lung cancer, experiment using a DNA methyltransferase inhibitor (5-azacytidine, AZA), methylation-specific PCR (MSP) and bisulfite sequencing were performed. NGS revealed changes in expression levels of EMT markers (E-cadherin, N-cadherin, fibronectin, vimentin, slug and snail) and stem cell markers (CD44 and CD87) in both BEAS-2B and A549 cells. Functional analysis revealed increased migration, invasion, sphere formation, and tumor development in mice after TGF-β treatment. Expression of slug and CD87 genes was activated following treatment with AZA and TGF-β. MSP and bisulfite sequencing indicated DNA demethylation of slug and CD87 genes. These results suggest that TGF-β induced EMT and cancer stemness acquisition could be associated with activation of slug and CD87 gene by their promoter demethylation.

Carbonic Anhydrase III Promotes Cell Migration and Epithelial-Mesenchymal Transition in Oral Squamous Cell Carcinoma

Epithelial–mesenchymal transition (EMT) is strongly correlated with tumor metastasis and contains several protein markers, such as E-cadherin. Carbonic anhydrase III (CA III) exhibits low carbon dioxide hydratase activity in cancer. However, the detailed mechanisms of CA III and their roles in oral cancer are still unknown. This study established a CA III-overexpressed stable clone and observed the expression of CA III protein in human SCC-9 and SAS oral cancer cell lines. The migration and invasion abilities were determined using a Boyden chamber assay. Our results showed that the overexpression of CA III protein significantly increased the migration and invasion abilities in oral cancer cells. Moreover, a whole genome array analysis revealed that CA III regulated epithelial–mesenchymal transition by reducing the expression of epithelial markers. Data from the GEO database also demonstrated that CA III mRNA is negatively correlated with CDH1 mRNA. Mechanistically, CA III increased the cell motility of oral cancer cells through the FAK/Src signaling pathway. In conclusion, this suggests that CA III promotes EMT and cell migration and is potentially related to the FAK/Src signaling pathway in oral cancer.

Down-regulation of miR-200c associates with poor prognosis of oral squamous cell carcinoma

BACKGROUND

MicroRNAs (miRNAs) are considered as promising cancer biomarkers. The aim of the present study is to investigate the prognostic significance of miR-200c in patients with oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

Quantitative real-time PCR (qRT-PCR) was used to determine the expression levels of miR-200c in 204 pairs of OSCC and adjacent noncancerous. Correlations between miR-200c expression levels and clinicopathological characteristics were investigated. Survival analysis was performed using the Kaplan-Meier method and log-rank test. Multivariate analysis of the prognostic factors was performed with a Cox proportional hazards regression model.

RESULTS

The expression of miR-200c was significantly down-regulated in OSCC tissues compared with adjacent non-tumor tissues (p < 0.0001). Low expression of miR-200c in tumor tissues was significantly correlated with the positive N classification (p = 0.013), advanced TNM stage (p = 0.007) and poor differentiation grade (p = 0.026). Lower miR-200c expression in patients was significantly associated with poor recurrence-free survival (RFS, p = 0.0003) and overall survival (OS, p = 0.0026). Multivariate analysis confirmed that low miR-200c expression was an independent predictor for poor RFS (hazard ratio (HR) 1.705, 95% CI 1.136-2.56, p = 0.01) and OS (HR 1.669, 95% CI 1.03-2.703, p = 0.037) in patients with OSCC.

CONCLUSION

Our results suggest that the miR-200c might be a potential prognostic biomarker for OSCC.

LINC00152 promotes the growth and invasion of oral squamous cell carcinoma by regulating miR-139-5p

Background

LINC00152 plays a crucial role in tumorigenesis and progression of multiple types of cancer. However, the biological significance of LINC00152 and its potential role in oral squamous cell carcinoma (OSCC) remain to be determined. In the present study, we investigated the role of LINC00152 and the underlying mechanism of its oncogenic activity in OSCC.

Materials and methods

The expression of LINC00152 in OSCC tissues and cell lines was detected using qRT-PCR. Cell proliferation, colony formation, migration, and invasion were measured using a cell counting kit, colony formation assay, wound healing, and transwell invasion assays, respectively. The target gene of LINC00152 was confirmed using a dual-luciferase reporter assay and qRT-PCR. A nude mouse model was established to analyze the function of LINC00152 in vivo.

Results

LINC00152 expression was significantly upregulated in OSCC tissues and cell lines compared with that in normal counterparts. Upregulated LINC00152 served as an independent prognostic predictor in patients with OSCC. Moreover, knockdown of LINC00152 inhibited cell proliferation, colony formation, migration, and invasion, and suppressed the epithelial to mesenchymal transition in vitro, as well as impairing tumor growth in vivo. A mechanistic investigation indicated that LINC00152 could directly bind to miR-139-5p in OSCC. LINC00152 expression was inversely correlated with miR-139 expression in OSCC tissues.

Conclusion

Taken together, these results suggested that LINC00152 may function as oncogene in OSCC and could be a potential therapeutic target in patients with OSCC.

MicroRNA-433 inhibits oral squamous cell carcinoma cells by targeting FAK

We investigated the involvement of microRNA-433 (miR-433) in the proliferation, migration, and invasiveness of oral squamous cell carcinoma (OSCC). Totally 108 OSCC tissues and adjacent normal tissues from patients with OSCC were collected. Also, transplanted tumor formation experiment in nude mice was conducted to verify the effect of miR-433 and FAK on subcutaneous transplanted tumor. The CD44⁺ stem cell from SCC-9 were collected and assigned into the blank, miR-433 mimics, mimics control, miR-433 inhibitors, inhibitors control, siFAK and miR-433 inhibitors + siFAK groups. The qRT-PCR and western blotting were used to detect miR-433, FAK, ERK, MEK, pERK and pMEK after transfection. Flow cytometry, MTT assay, scratch test and Transwell assay were performed to determine the cell proportion, growth, migration and invasion of SCC-9 cells. In cell line SCC-9, expression of CD133, Oct-4, and BIM-1 was greater in CD44⁺ cells than CD44^- cells, indicating that CD44⁺ cells had characteristics of tumor stem cells. Expression of FAK, ERK, MEK, p-ERK and p-MEK was decreased in tumor tissues from the CD44^-, miR-433, and siFAK groups. Expression of MiR-433 mRNA was elevated, while levels of FAK, ERK, MEK, p-ERK, and p-MEK mRNA were all decreased in the miR-433 mimics group. In the miR-433 mimics and siFAK groups, cell proliferation, migration, and invasion were all decreased, while the opposite trends were seen in the miR-433 inhibitor group. These results indicate that miR-433 downregulates FAK through the ERK/MAPK signaling pathway to inhibit the proliferation, migration, and invasiveness of SCC-9 OSCC cells.

MicroRNA-27a-3p Modulates the Wnt/β-Catenin Signaling Pathway to Promote Epithelial-Mesenchymal Transition in Oral Squamous Carcinoma Stem Cells by Targeting SFRP1

This study aimed to elucidate how microRNA27a-3p (miR-27a-3p) modulates the Wnt/β-catenin signaling pathway to promote the epithelial-mesenchymal transition (EMT) in oral squamous carcinoma stem cells (OSCSCs) by targeting secreted frizzled-related protein 1 (SFRP1). Flow cytometry was used to sort OSCSCs from the SCC-9 and Tca8113 cell lines. The OSCSCs were randomly assigned into the miR-27a-3p inhibitors group, the miR-27a-3p inhibitors-NC group, the si-SFRP1 group, the si-SFRP1 + miR-27a-3p inhibitors group and the blank group. A luciferase reporter, immunofluorescence and Transwell assays were performed to detect luciferase activity, SFRP1, and cell migration and invasion, respectively. The mRNA expression of miR-27a-3p, SFRP1 and EMT markers (E-cadherin, N-cadherin, vimentin and ZEB1) were detected using qRT-PCR. The protein expression of SFRP1, EMT markers and the proteins of the Wnt/β-catenin signaling pathway was detected by Western blotting. OSCSCs showed up-regulated miR-27a-3p, Wnt/β-catenin signaling pathway-related proteins, vimentin, N-cadherin and ZEB1 and down-regulated SFRP1 and E-cadherin. MiR-27a-3p targeted SFRP1. Down-regulated miR-27a-3p resulted in increased E-cadherin and SFRP1 but decreased vimentin, N-cadherin, ZEB1, the Wnt/β-catenin signaling pathway-related proteins, and invasive and migratory cells. Silenced SFRP1 reversed this effect. We found that miR-27a-3p modulated the Wnt/β-catenin signaling pathway to promote EMT in OSCSCs by down-regulating SFRP1.

Evidence for circulating cancer stem-like cells and epithelial-mesenchymal transition phenotype in the pleurospheres derived from lung adenocarcinoma using liquid biopsy

Lung cancer stem cells are supposed to be the main drivers of tumor initiation, maintenance, drug resistance, and relapse of the disease. Hence, identification of the cellular and molecular aspects of these cells is a prerequisite for targeted therapy of lung cancer. Currently, analysis of circulating tumor cells has the potential to become the main diagnostic technique to monitor disease progression or therapeutic response as it is non-invasive. However, accurate detection of circulating tumor cells has remained a challenge, as epithelial cell markers used so far are not always trustworthy for detecting circulating tumor cells, especially during epithelial-mesenchymal transition. As cancer stem cells are the only culprit to initiate metastatic tumors, our aim was to isolate and characterize circulating tumor stem cells rather than circulating tumor cells from the peripheral blood of NSCLC adenocarcinoma as limited data are available addressing the gene expression profiling of lung cancer stem cells. Here, we reveal that CD44(+)/CD24(-) population in circulation not only exhibit stem cell-related genes but also possess epithelial-mesenchymal transition characteristics. In conclusion, the use of one or more cancer stem cell markers along with epithelial, mesenchymal and epithelial mesenchymal transition markers will prospectively provide the most precise assessment of the threat for recurrence and metastatic disease and has a great potential for forthcoming applications in harvesting circulating tumor stem cells and their downstream applications. Our results will aid in developing diagnostic and prognostic modalities and personalized treatment regimens like dendritic cell-based immunotherapy that can be utilized for targeting and eliminating circulating tumor stem cells, to significantly reduce the possibility of relapse and improve clinical outcomes.

Circulating tumor stem like cells in oral squamous cell carcinoma: An unresolved paradox

OBJECTIVE

Circulating tumor cells (CTCs) are increasingly gaining importance due to their immense potential in enhancing diagnosis, prognosis and response to therapy in solid malignancies. Therefore, we aimed to comprehend the molecular diversity and critical role of this disseminated tumor population in OSCC.

METHODOLOGY

CD44+ subpopulation was isolated using immuno-magnetic cell separation and their purity was validated using flow cytometry. Characterisation of self renewal potential and resistance to chemotherapy was assessed using tumor sphere forming and cytotoxicity assay. Gene expression profile of pertinent CSC (CD44s, CD44v3, CD44v6) and stemness markers (Bmi1 and Nanog) was carried out in CD44+ cells using Real Time PCR. Predominantly expressed markers and their association with clinico-pathological conditions were substantiated in 30 OSCC patients.

RESULT

Flow cytometry analysis depicted a predominant population of CD44+CD24-CD45- cells suggesting that circulating tumor cells had a subpopulation of CSC like cells in the circulation. These cells demonstrated increased sphere forming capability and intrinsic chemo-resistance compared to non-CSC, thus indicating the CSC features of self-renewal and chemo-resistance. Additionally, CD44+ cells showed significantly increased expression levels of CD44v6 and Nanog compared to CD44- cells. Clinically, expression pattern of CD44v6 and Nanog correlated with different anatomical subsites, loco-regional aggressiveness of the disease and recurrence, thus opening newer avenues that can be explored for better prognostic and therapeutic implications.

CONCLUSION

This study explored the inevitable role of CD44v6 and Nanog as circulating stem like cell markers in assessment of loco-regional aggressiveness, detection of relapse and therapeutic response and resistance.

Role of miRNA dynamics and cytokine profile in governing CD44v6/Nanog/PTEN axis in oral cancer: modulating the master regulators

Late diagnosis, low therapeutic response, and metastasis are accountable for poor 5-year survival rate of OSCC. These failures are attributed to the existence of "cancer stem cell (CSC)" subpopulation. Hence, it is necessary to identify and understand the mechanism of CSCs in tumor development, metastasis, and chemotherapeutic response. Propelling evidences suggest that microRNA (miRNA)-mediated regulation and cytokines of tumor microenvironment have the ability to modulate CSC signalling pathway; however, their exact mechanism needs to be elucidated. Thus, in this study, we characterized CSC markers and highlighted the miRNA dynamics and cytokine profile regulating these CSCs in a pathway-dependent manner. Our results demonstrated CD44+ subpopulation as tumor-initiating cells with self-renewal capability, tumorigenic growth potential and intrinsic chemoresistance. These tumors exhibited increased expression of CSC markers (CD44v3, CD44v6, Nanog, and Bmi1) and significantly reduced expression of PTEN and ATM in OSCC patients. Pathway analysis of these CSC markers demonstrated a prospective pathway regulated by miRNA and cytokine network. On analyzing these modulators, we observed decreased expression of miRNA542-3p, miRNA34a and miRNA9, and significant upregulation of miRNA21, thus forming an unexplored axis. Cytokine profiling revealed significantly increased levels of IL-6 and IL-8 compared to normals and demonstrated their strong association with CD44v6. Collectively, this study indicates that miR5423p and miR34a targets the CD44v6-Nanog-PTEN axis, thus playing a vital role in regulating the CSC properties. Furthermore, we speculate an impinging role of cytokines IL-6 and IL-8 in regulating this CSC-mediated pathway which can have prognostic and therapeutic implications.

A novel method to limit breast cancer stem cells in states of quiescence, proliferation or differentiation: Use of gel stress in combination with stem cell growth factors

The majority of cancer stem cells exist in the G0, or quiescent phase of the cell cycle. However, the cells can escape quiescence following routine radiotherapy and chemotherapy, resulting in tumor recurrence. Presently, achieving the accurate regulation of cancer stem cell growth in order to study a specific state, including the quiescent (mostly G0 or G1 phase), proliferative (mostly S phase) or differential (mostly G2/M phase) states, can be challenging. This makes the determination of cell cycle state-specific characteristics and analysis of potential intervention treatments difficult, particularly for quiescent cells. Breast cancer stem cells were cultured on a soft or hard agar matrix surface in the presence or absence of stem cell growth factors. Cells could be successfully limited in either the quiescent, proliferative or differentiated states. These findings provide a foundation for further study of the cell cycle in breast cancer stem cells.

Mechanisms of growth-promoting and tumor-protecting effects of epithelial nicotinic acetylcholine receptors

Although the role of nicotine as a carcinogen is debatable, it is widely accepted that it contributes to cancer by promoting growth and survival of mutated cell clones and protecting them from the chemo- and radiotherapy-induced apoptosis. On the cell membrane (cm), the nicotinic acetylcholine (ACh) receptors (nAChRs) implement upregulation of proliferative and survival genes. Nicotine also can permeate cells and activate mitochondrial (mt)-nAChRs coupled to inhibition of the mitochondrial permeability transition pore (mPTP) opening, thus preventing apoptosis. In this study, we sought to pin down principal mechanisms mediating the tumor-promoting activities of nicotine resulting from activation of cm- and mt-nAChRs in oral and lung cancer cells, SCC25 and SW900, respectively. Activated cm-nAChRs were found to form complexes with receptors for EGF and VEGEF via the α7 and β2 nAChR subunits, respectively, whereas activated mt-nAChRs physically associated with the intramitochondrial protein kinases PI3K and Src via the α7 and β4 subunits. This was associated with upregulated expression of cyclin D1/activation of ERK1/2 and inhibition of mPTP opening, respectively, as well as upregulated proliferation and resistance to H(2)O(2)-induced apoptosis. The molecular synergy between cm-nAChRs and growth factor receptors helps explain how one biological mediator, such as ACh, can modulate activity of the other, such as a growth factor, and vice versa. Establishment of functional coupling of mt-nAChRs to regulation of mPTP opening provides a novel mechanism of nicotine-dependent protection from cell death. Further elucidation of this novel mechanism of tumor-promoting activities of nicotine should have a strong translational impact, because extraneuronal nAChRs may provide a novel molecular target to prevent, reverse, or retard progression of both nicotine-related and unrelated cancers.