Update of molecular pathobiology in oral cancer: a review

LncRNA FOXD2-AS1 promotes the growth, invasion and migration of OSCC cells by regulating the MiR-185-5p/PLOD1/Akt/mTOR pathway

Although lncRNAs are recognized to contribute to the development of oral squamous-cell carcinoma (OSCC), their exact function in invasion and cell migration is not clear. In this research, we explored the molecular and cellular mechanisms of FOXD2-AS1 in OSCC. Prognostic and bioinformatics analyses were used to test for the differential expression of FOXD2-AS1-PLOD1. Following FOXD2-AS1 suppression or overexpression, changes in cell viability were measured using the CCK-8 test; changes in cell migration and invasion abilities were measured using the migration and the Transwell assay. The expression of associated genes and proteins was found using Western blot and RT-qPCR. Analysis of luciferase reporter genes was done to look for regulatory connections between various molecules. The FOXD2-AS1-PLOD1 pair, which was highly expressed in OSCC, was analyzed and experimentally verified to be closely related to the prognosis of OSCC, and a nomogram model and correction curve were constructed. The inhibition of FOXD2-AS1 resulted in the reduction of cell activity, migration, invasion ability and changes in genes related to invasion and migration. In vivo validation showed that inhibition of FOXD2-AS1 expression slowed tumor growth, and related proteins changed accordingly. The experiments verified that FOXD2-AS1 negatively regulated miR-185-5 p and that miR-185-5 p negatively regulated PLOD1. In addition, it was found that the expression of PLOD1, p-Akt and p-mTOR proteins in OSCC cells was reduced by the inhibition of FOXD2-AS1, and FOXD2-AS1 and PLOD1 were closely related to the Akt/mTOR pathway. Increased expression of FOXD2-AS1 promotes OSCC growth, invasion and migration, which is important in part by targeting miR-185-5 p/PLOD1/Akt/mTOR pathway activity.

Role of innate host defense proteins in oral cancerogenesis

It is nowadays well accepted that chronic inflammation plays a pivotal role in tumor initiation and progression. Under this aspect, the oral cavity is predestined to examine this connection because periodontitis is a highly prevalent chronic inflammatory disease and oral squamous cell carcinomas are the most common oral malignant lesions. In this review, we describe how particular molecules of the human innate host defense system may participate as molecular links between these two important chronic noncommunicable diseases (NCDs). Specific focus is directed toward antimicrobial polypeptides, such as the cathelicidin LL-37 and human defensins, as well as S100 proteins and alarmins. We report in which way these peptides and proteins are able to initiate and support oral tumorigenesis, showing direct mechanisms by binding to growth-stimulating cell surface receptors and/or indirect effects, for example, inducing tumor-promoting genes. Finally, bacterial challenges with impact on oral cancerogenesis are briefly addressed.

Circ-ILF2 in oral squamous cell carcinoma promotes cisplatin resistance and induces M2 polarization of macrophages

Cisplatin (CDDP) chemoresistance is one of the predominant factors in oral squamous cell carcinoma (OSCC) treatment failure. Uncovering the mechanisms underlying CDDP resistance is of great importance in OSCC therapy. Circular RNAs (circRNAs) are a newly discovered class of noncoding RNAs, which are reported to participate in the progression of various diseases, including cancer. However, the function of circRNAs in CDDP resistance in OSCC remains unclear. Quantitative reverse transcription PCR was used to search for different circRNAs between OSCC cell lines and CDDP-resistant cell lines. The results showed that circ-ILF2 expression was higher in CDDP-resistant OSCC cell lines. The stability of circ-ILF2 was also confirmed using RNase R and actinomycin D assays. Functional experiments, including cytotoxicity, apoptosis and growth rate assays, showed that upregulation of circ-ILF2 contributes to CDDP resistance. Luciferase reporter-gene, RNA pull-down and quantitative real-time PCR (RT-qPCR) assays showed that circ-ILF2 functions as a microRNA sponge for miR-1252. Luciferase reporter assays, RNA pull-down, RT-qPCR and Western blotting showed that miR-1252 directly targeted and regulated the expression of KLF8. Circ-ILF2 plays an important role in CDDP resistance in OSCC. Circ-ILF2 exerts its function through the miR-1252/KLF8 pathway. In addition, tumour-associated macrophages (TAM) play important roles in cancer progressions, our results showed that circ-ILF2 in OSCC cells induced the M2 polarization of macrophages which provided new thoughts on immunotherapy. Our results suggest that circ-ILF2 may represent a potential therapeutic target in CDDP-resistant OSCC.

The role and mechanism of circ-BNC2 on the malignant progression of oral squamous cell carcinoma

BACKGROUND

Circular RNAs (circRNAs) play a key part in the progression of oral squamous cell carcinoma (OSCC). However, the role of circ-BNC2 (circRNA ID hsa_circ_0086414) in OSCC progression is still unclear.

METHODS

Plasmid transfection was used to induce overexpression of circ-BNC2. RNA expression of circ-BNC2, microRNA-142-3p (miR-142-3p) and GNAS complex locus (GNAS) was detected by quantitative real-time polymerase chain reaction. Protein expression was assessed by western blot assay or immunohistochemistry assay. Cell proliferation was investigated by 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, colony formation assay and flow cytometry analysis. Cell migratory and invasive abilities and cell apoptosis were assessed by transwell assay and flow cytometry analysis, respectively. Oxidative stress was evaluated by superoxide dismutase activity detection assay, lipid peroxidation malondialdehyde assay and cellular reactive oxygen species assay. The binding relationship between miR-142-3p and circ-BNC2 or GNAS was proved by dual-luciferase reporter assay and RNA immunoprecipitation assay. The impacts of circ-BNC2 overexpression on tumor growth in vivo were unveiled by a xenograft mouse model assay.

RESULTS

Circ-BNC2 expression was downregulated in OSCC tissues and cells when compared with adjacent healthy tissues and normal human oral keratinocytes. Circ-BNC2 overexpression repressed the proliferation, migration and invasion of OSCC cells but induced cell apoptosis and oxidative stress. Additionally, circ-BNC2 overexpression inhibited tumor growth in vivo. Furthermore, circ-BNC2 bound to miR-142-3p, and miR-142-3p targeted GNAS. MiR-142-3p mimic attenuated circ-BNC2 overexpression-mediated effects on the proliferation, migration, invasion, apoptosis and oxidative stress of OSCC cells. The regulation of miR-142-3p in OSCC cell tumor properties involved GNAS. Further, circ-BNC2 introduction promoted GNAS expression by inhibiting miR-142-3p.

CONCLUSION

Circ-BNC2 suppressed OSCC malignant progression by upregulating GNAS expression in a miR-142-3p-dependent manner, which suggested that circ-BNC2 might be a novel target for OSCC therapy.

Therapeutic potential of curcumin and its nanoformulations for treating oral cancer

The global incidence of oral cancer has steadily increased in recent years and is associated with high morbidity and mortality. Oral cancer is the most common cancer in the head and neck region, and is predominantly of epithelial origin (i.e. squamous cell carcinoma). Oral cancer treatment modalities mainly include surgery with or without radiotherapy and chemotherapy. Though proven effective, chemotherapy has significant adverse effects with possibilities of tumor resistance to anticancer drugs and recurrence. Thus, there is an imperative need to identify suitable anticancer therapies that are highly precise with minimal side effects and to make oral cancer treatment effective and safer. Among the available adjuvant therapies is curcumin, a plant polyphenol isolated from the rhizome of the turmeric plant Curcuma longa. Curcumin has been demonstrated to have anti-infectious, antioxidant, anti-inflammatory, and anticarcinogenic properties. Curcumin has poor bioavailability, which has been overcome by its various analogues and nanoformulations, such as nanoparticles, liposome complexes, micelles, and phospholipid complexes. Studies have shown that the anticancer effects of curcumin are mediated by its action on multiple molecular targets, including activator protein 1, protein kinase B (Akt), nuclear factor κ-light-chain-enhancer of activated B cells, mitogen-activated protein kinase, epidermal growth factor receptor (EGFR) expression, and EGFR downstream signaling pathways. These targets play important roles in oral cancer pathogenesis, thereby making curcumin a promising adjuvant treatment modality. This review aims to summarize the different novel formulations of curcumin and their role in the treatment of oral cancer.

Overexpression of circCDR1as drives oral squamous cell carcinoma progression

BACKGROUND

Circular RNAs (circRNAs) mediate the progression of human cancers, including oral squamous cell carcinoma (OSCC). The aim of this study was to investigate the functions of circRNA CDR1 Antisense RNA (circCDR1as) in OSCC. Moreover, the relationships among circCDR1as, microRNA-876-5p (miR-876-5p) and Solute Carrier Family 7 Member 11 (SLC7A11) in OSCC development were explored.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to determine the expression of circCDR1as, miR-876-5p, and SLC7A11. Cell Counting kit-8 assay, cell colony formation assay, and 5-ethynyl-2'-deoxyuridine (EDU) assay were used to assess cell proliferation. Transwell assay was adopted for cell migration and invasion.

RESULTS

CircCDR1as level was aberrantly elevated in OSCC tissues and cells. Overexpression of circCDR1as promoted autophagy, cell cycle, proliferation, and metastasis and repressed apoptosis in OSCC cells. CircCDR1as directly targeted miR-876-5p and miR-876-5p interacted with SLC7A11. MiR-876-5p overexpression reversed the effects of circCDR1as elevation on OSCC cell autophagy, cell cycle, growth, motility, and apoptosis. Inhibition of miR-876-5p aggravated the malignant behaviors of OSCC cells, while SLC7A11 silencing ameliorated the impacts. In addition, circCDR1as knockdown blocked tumor growth in vivo.

CONCLUSION

CircCDR1as acted as an oncogene in OSCC progression through elevating SLC7A11 by targeting miR-876-5p.

Serum Response Factor-Regulated IDO1/Kyn-Ahr Pathway Promotes Tumorigenesis of Oral Squamous Cell Carcinoma

Serum response factor (SRF) regulates pro-carcinogenic genes in various cancers, but its role in oral squamous cell carcinoma (OSCC) remains unclear. SRF expression in 70 OSCC samples was detected via immunohistochemistry. Abundant SRF expressed in OSCC tissues was closely associated with tumor metastasis. SRF-overexpressing OSCC cells were constructed to evaluate how SRF affects OSCC cell tumorigenesis and epithelial-to-mesenchymal transition (EMT) in vitro and in vivo. Overexpressed SRF increased OSCC cell migration and invasion in vitro and tumor growth and invasion in vivo. This promoted EMT, characterized by decreased and increased expression of E- and N-cadherin, respectively. Furthermore, an analysis of RNA sequences of transcriptional targets of SRF showed that SRF transactivated the indoleamine 2, 3-dioxygenase 1 (IDO1)/kynurenine-aryl hydrocarbon receptor (Kyn-AhR) signaling pathway in OSCC cell lines. Direct SRF binding to the IDO1 gene promoter upregulated transcription, which was detected through chromatin immunoprecipitation and dual luciferase reporter assays. Inhibiting IDO1 or AhR impaired SRF-induced migration and invasion and prevented EMT in OSCC cells. Our results demonstrated that SRF is a critical regulator of the IDO1/Kyn-AhR signaling pathway. This in turn increases OSCC cell migration and invasion by modulating EMT, which, consequently, favors OSCC cell growth and metastasis. We revealed a novel molecular mechanism through which SRF modulates OSCC metastasis. This should provide potential targets or biomarkers for OSCC diagnosis and treatment.

MicroRNA-382-5p Promotes Oral Squamous Cell Carcinoma Development and Progression by Negatively Regulating PTEN Expression

PURPOSE

Oral squamous cell carcinoma (OSCC) local recurrence and distant metastasis remain a poorly understood clinical challenge. The objective of this study was to investigate how dysregulation of miR-382-5p impacts invasion and dissemination of OSCC.

METHODS

Tissue samples were collected from 20 subjects with OSCC. Expression levels of miR-382-5p were determined by quantitative real-time polymerase chain reaction (qRT-PCR), and correlations with clinical characteristics were investigated. qRT-PCR was used to determine the miR-382-5p and peptidyl-prolyl cis/trans isomerase (PTEN) expression in tumor tissues, adjacent normal tissues, normal human oral keratinocyte line, and OSCC line (SCC-9). Cell proliferation, invasion, and migration of knock-in and knock-down miR-382-5p transfectants were assessed using cell counting kit-8 and Transwell assays. PTEN was confirmed to be a downstream target using a TargetScan prediction, dual-luciferase reporter assays, and western blot analysis. Statistical analysis of experimental data was performed with SPSS 22.0 software.

RESULTS

We found high expression of miR-382-5p and significant downregulation of PTEN in tumor tissues and SCC-9 cells from OSCC patients (P < .05). miR-382-5p expression was lower in early stage (I + II) than in late stage (III + IV), while PTEN exhibited higher expression in early stage (I + II) instead of in late stage (III + IV) (P < .05). In addition, overexpression of miR-382-5p promoted the proliferation, invasion, and migration of OSCC cells. However, the proliferation, invasion, and migration of OSCC cells were inhibited after suppression of miR-382-5p. Finally, PTEN is downregulated by miR-382-5p.

CONCLUSION

MiR-382-5p supports proliferation, invasion, and migration of OSCC cells through the PTEN pathway. Further investigation may improve our understanding of OSCC local recurrence and distant metastasis.

Long noncoding RNA TFAP2A-AS1 promotes oral squamous cell carcinoma cell growth and movement via competitively binding miR-1297 and regulating TFAP2A expression

Oral squamous cell carcinoma (OSCC) is an aggressive and common malignancy in the head and neck, characterized by poor prognosis and high incidence. This study aimed to investigate the role of long noncoding RNA TFAP2A-AS1 in OSCC. The competing endogenous RNA network of TFAP2A-AS1 was constructed by bioinformatics analysis. The expressions of miR-1297, TFAP2A-AS1, and TFAP2A were measured by quantitative reverse transcription-polymerase chain reaction. The correlations of TFAP2A-AS1, miR-1297, and TFAP2A with clinicopathological characteristics of OSCC were assessed. RNA immunoprecipitation and dual-luciferase reporter assay were used to identify the target of miR-1297. Cell proliferation was measured by colony formation assay and [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay. Transwell assay and wound healing assay were performed to assess cell movement. TFAP2A-AS1 and TFAP2A were upregulated in OSCC and their expression levels were positively correlated. The levels of TFAP2A-AS1, miR-1297, and TFAP2A were also associated with lymphatic metastasis and the tumor-node-metastasis (TNM) stage of OSCC patients. TFAP2A-AS1 acted as a miR-1297 sponge. OSCC cell growth and movement were inhibited by miR-1297. Changes in the miR-1297 expression abolished the effects of TFAP2A-AS1 on OSCC cells. Additionally, TFAP2A was a target of miR-1297. TFAP2A promoted OSCC cell growth and migration/invasion, indicating that TFAP2A mediated the effects of TFAP2A-AS1 and miR-1297. TFAP2A-AS1 exerts an oncogenic effect in OSCC via the TFAP2A-AS1/miR-1297/TFAP2A axis, which may provide new targets and strategies for OSCC treatments.

circ_0004872 inhibits proliferation, invasion, and glycolysis of oral squamous cell carcinoma by sponged miR-424-5p

Objective

Oral squamous cell carcinoma (OSCC) is one of the most common oral malignant tumors. circ_0004872 can inhibit the progression of gastric cancer, but its effect on the growth and metastasis of OSCC is still unclear.

Methods

qRT‐PCR was used to detect the expression levels of circ_0004872 and miR‐424‐5p in cancer tissues of OSCC patients and adjacent normal tissues, OSCC cell lines, and human normal oral keratinocytes (HOK). CCK‐8, cell colony formation, flow cytometry, and transwell assay were used to detect cell proliferation rate, viability, apoptosis rate, and invasion ability. Use glucose/lactic acid kit to assay cell glycolysis ability. The dual‐luciferase reporter gene experiment and RIP experiment verified the relationship between circ_0004872 and miR‐424‐5p. The protein levels were examined by Western blot.

Results

The expression of circ_0004872 was significantly downregulated in OSCC tissues and cells, and the overexpression of circ_0004872 inhibited the proliferation, vitality, invasion, and glycolysis of OSCC cells, and promoted apoptosis. The expression of miR‐424‐5p was greatly upregulated in OSCC tissues and OSCC cells. circ_0004872 can adsorb miR‐424‐5p in OSCC cells, and circ_0004872 can reverse the promoting effect of miR‐424‐5p overexpression on the process of OSCC cells.

Conclusion

circ_0004872 suppresses the proliferation, invasion, and glycolysis of OSCC cells by sponged miR‐424‐5p, and promotes apoptosis, which can be used as a potential target for early diagnosis and targeted therapy of OSCC.

Clinicopathological and Prognostic Significance of Stromal Patterns in Oral Squamous Cell Carcinoma

Background

Stromal patterns (SP), especially desmoplastic reactions, have recently gained attention as indicators of malignant potential in cancer. In this study, we explored the clinicopathological and prognostic significance of the SP in oral squamous cell carcinoma (OSCC).

Materials and Methods

We reviewed 232 cases of surgically resected OSCC that were not treated with neoadjuvant chemoradiotherapy. We categorized the SP of the OSCC into four groups: immune/inflammatory (84 cases), mature (14 cases), intermediate (78 cases), or immature (56 cases).

Results

The SP category was significantly associated with various clinicopathological factors, such as the histological grade, lymphovascular invasion, neural invasion, and a diffuse invasion pattern. For each of the factors, the immune/inflammatory type was associated with favorable categories, while the immature type was associated with unfavorable categories (p ≤ 0.001). The SP category was also shown to be a prognostic predictor: the 5-year relapse-free survival (RFS) rate was 72.0% for the immune/inflammatory type, 66.7% for the intermediate/mature type, and 31.2% for the immature type (p < 0.0001), and the 5-year overall survival (OS) rate was 85.1% for the immune/inflammatory type, 76.4% for the intermediate/mature type, and 50.0% for the immature type (p < 0.0001). In multivariate analyses, the SP category was identified as an independent prognostic factor for RFS and OS.

Conclusion

Our SP categorization method provides valuable prognostic information in OSCC.

Serine hydroxymethyltransferase 2 (SHMT2) potentiates the aggressive process of oral squamous cell carcinoma by binding to interleukin enhancer-binding factor 2 (ILF2)

Oral squamous cell carcinoma (OSCC) is a frequent threatening head and neck malignancy. Serine hydroxymethyltransferase 2 (SHMT2) was identified to be upregulated in OSCC and its high expression was associated with poor patient prognosis. This paper set out to assess the influence of SHMT2 on OSCC progression and the potential mechanisms related to interleukin enhancer-binding factor 2 (ILF2). First of all, reverse transcription-quantitative PCR (RT-qPCR) and western blot examined the expression of SHMT2 and ILF2 in OSCC cells. Cell Counting Kit-8 (CCK-8) and colony formation assays appraised cell proliferation. Terminal-deoxynucleotidyl Transferase Mediated Nick End Labeling (TUNEL) staining was to estimate the apoptotic rate of cells. Further, wound healing and transwell assays verified the migration and invasion of cells. Western blot was adopted to detect the expression of factors related to apoptosis, migration, and epithelial–mesenchymal transition (EMT). The possible interaction of SHMT2 and ILF2 was predicted by a Molecular INTeraction (MINT) and BioGRID databases and determined using co-immunoprecipitation (IP) assay. Subsequently, ILF2 was overexpressed to investigate whether SHMT2 regulated OSCC progression by binding to ILF2. Results implied that SHMT2 possessed increased expression in OSCC cells, and OSCC cell viability, migration, invasion, EMT were inhibited and apoptosis was potentiated after its silencing. ILF2 bound to SHMT2 and ILF2 expression was downregulated after SHMT2 silencing in OSCC cells. Importantly, ILF2 overexpression abolished the suppressive role of SHMT2 interference in the progression of OSCC. Collectively, SHMT2 could promote the progression of OSCC by binding to ILF2.

Long Noncoding RNA LINC00941 Promotes Cell Proliferation and Invasion by Interacting with hnRNPK in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a prevalent carcinoma of the head, neck and mouth. Recently studies involving the role of long noncoding RNAs (lncRNAs) that play key regulatory roles in altering gene expression has been reported in the context of promoting tumorigenesis. However, the functions of lncRNAs in the context of oral squamous cell carcinoma have not been extensively described. In this study, we report a never identified before lncRNA, LINC00941, which was highly expressed in OSCC tissues and cells. Expression of LINC00941 promoted cell proliferation, migration, invasion, and metastasis of OSCC cells In Vitro by inducing epithelial-mesenchymal transition (EMT) and activating the Wnt/β-catenin signaling cascade. In silico analyses revealed heterogeneous nuclear ribonucleoprotein K (hnRNPK) to be a strong positive regulator of LINC00941 activity. Experimental verification of this association revealed a direct interaction of LINC00941 and hnRNPK to induce cell growth and invasion by activating EMT in OSCC cells. Therefore, our study reports that LINC00941 promotes progression of OSCC by its interaction with hnRNPK, and it may present a promising strategy for diagnosis and treatment of OSCC.

MicroRNA-141-3p inhibits the progression of oral squamous cell carcinoma via targeting PBX1 through the JAK2/STAT3 pathway

Oral squamous cell carcinoma (OSCC), which is the most common epithelial malignant neoplasm in the head and neck, is characterized by local infiltration and metastasis of lymph nodes. The five-year survival rate of OSCC remains low despite the advances in clinical methods. miR-141-3p has been shown to activate or inhibit tumorigenesis. However, the effects of miR-141-3p on invasion and migration of OSCC remain unclear. The present study aimed to evaluate the effects of miR-141-3p on invasion, proliferation, and migration in oral squamous cell carcinoma (OSCC). Reverse transcription quantitative PCR, western blotting and immunohistochemistry were used to detect microRNA(miR)-141-3p and pre-B-cell leukaemia homeobox-1 (PBX1) expression in OSCC tissues and cell lines. The luciferase reporter assay was used to detect targets of miR-141-3p in OSCC. MTT, Transwell and wound healing assays were used to determine the cell proliferation and invasive and migratory abilities, respectively. Expression of constitutive phosphorylated (p)-Janus kinase 2 (JAK2) and p-signal transducer and activator of transcription 3 (STAT3) was detected using western blotting in tissues and cells. miR-141-3p expression was decreased in OSCC tissues and cells, while PBX1 protein expression was increased compared with non-cancerous controls. The result from the dual-luciferase reporter assay revealed that PBX1 was the direct target of miR-141-3p in OSCC tissues. Furthermore, miR-141-3p overexpression and PBX1 knockdown could reduce cell invasion, proliferation and migration, and inhibit the JAK2/STAT3 pathway; however, miR-141-3p downregulation had the opposite effects. In addition, silencing of PBX1 using small interfering RNA could weaken the effects of miR-141-3p inhibitor on JAK2/STAT3 pathway and cell progression in CAL27 cells. In summary, the findings from this study indicated that miR-141-3p upregulation could inhibit OSCC cell invasion, proliferation and migration, by targeting PBX1 via the JAK2/STAT3 pathway.

LINC00472 suppresses oral squamous cell carcinoma growth by targeting miR-455-3p/ELF3 axis

LINC00472 is reported to play a role in suppressing tumors in cancers such as lung cancer and hepatocellular carcinoma, among others. We made investigations into the effects of LINC00472 in oral squamous cell carcinoma (OSCC) progression to explore the underlying molecular mechanisms. By qRT-PCR, we assessed the LINC00472 expression in OSCC tissues and cells and performed functional analysis to investigate how LINC00472/miR-455-3p/ELF3 impacts OSCC cell proliferation, apoptosis, and cell cycle. The role that LINC00472 plays in OSCC tumor growth was examined by establishing a xenograft model. Down-regulation of LINC00472 occurred in tissues and cells of an OSCC tumor. LINC00472 overexpression caused OSCC cell proliferation to be inhibited, cell apoptosis to be promoted, and cell cycle arrest to be induced. As a competing endogenous RNA (ceRNA), LINC00472 can block miR-455-3p function and further promote ELF3 expression. The overexpression of miR-455-3p or ELF3 knockdown was shown to be capable of reversing the anti-tumor effects of LINC00472 in OSCC. In vivo experiments confirmed the tumor-suppressing role of LINC00472 in the progression of OSCC. In short, we found that the novel LINC00472 inhibits OSCC growth via the miR-455-3p/ELF3 axis. LINC00472 and its targeted miR-455-3p/ELF3 axis may represent valuable targets for treating OSCC.

Circular RNAs as a Diagnostic Biomarker in Oral Squamous Cell Carcinoma: A Meta-Analysis

PURPOSE

Studies have found a positive correlation between various cancers and circular RNAs (circRNAs), which are newly discovered noncoding RNAs. However, limited scientific evidence is available to prove the clinical value of circRNAs in the presentation of oral squamous cell carcinoma (OSCC). This study aimed to comprehensively explore the potential of circRNAs as diagnostic indexes of OSCC.

METHODS

Online databases were systematically searched to identify published literature on the discovery of circRNAs in OSCC. Data were acquired from each reviewed study and collated to create a 2 × 2 eventuality table. Hierarchical analysis of the literature was conducted for the type of cancer, year of publication, and the sample size of each study. The diagnostic accuracy was calculated using indexes such as the pooled sensitivity and specificity and critically assessed using the Quality Assessment for Studies of Diagnostic Accuracy 2.

RESULTS

This meta-analysis included findings of 6 studies on 335 patients diagnosed with OSCC. These 6 studies examined 7 circRNAs, 5 in tissues and 2 in the saliva of patients with OSCC. When used as a diagnostic tool for OSCC, circRNAs manifested a sensitivity level of 0.72 (95% confidence interval: 0.67 to 0.76) and a degree of specificity of 0.81 (95% confidence interval: 0.76 to 0.85), with a general projected probability rate of 3.82 (95% confidence interval: 2.98 to 4.91) being positive and 0.35 (95% confidence interval: 0.29 to 0.41) being negative. The combined probability rate was 11.07 (95% confidence interval: 7.64 to 16.04), comprising a total of 0.76 (95% confidence interval: 0.72 to 0.79) of the region under the curve. A higher diagnostic value was found for salivary circRNAs (diagnostic odds ratio = 17.52; 95% CI: 10.11 to 30.35) than for tissue circRNAs (diagnostic odds ratio = 8.47; 95% CI: 5.6 to 12.83). This indicated that circRNAs showed a good discrimination ability as biomarkers of OSCC.

CONCLUSIONS

circRNAs showed high accuracy in the diagnosis of OSCC and could be used as prospective biomarkers to facilitate the diagnostic process.

Overexpression of methyltransferase-like 3 and 14 in oral squamous cell carcinoma

OBJECTIVES

This study aimed to determine expressions of methyltransferase-like 3 (METTL3) and METTL14, two enzymes essential for mRNA methylation at the adenosine (m⁶ A), in oral squamous cell carcinoma (OSCC) and to investigate in vitro aggressiveness of their aberrant expressions.

METHODS

METTL3 and METTL14 expressions in 50 OSCC and 11 normal oral tissues were examined by immunohistochemistry. METTL3 and METTL14 expressions and m⁶ A amounts were determined in three OSCC cell lines, including HN5, HN6, and HN15. Cell proliferation, migration, and invasion were studied by BrdU, wound healing, and Transwell chamber assays, after silencing of METTL3, METTL14, or both by siRNA transfection.

RESULTS

Immunostaining of METTL3 and METTL14 was localized in cancer cell nuclei. The mean percentages of METTL3- and METTL14-positive cells were significantly increased in OSCC tissues (p < 0.001). The percentages of METTL3- and METTL14-positive cells were correlated with the advanced pTNM stages (p < 0.05) and with the degrees of histopathological differentiation in OSCC (r = 0.564 and r = 0.316, respectively; p < 0.001). By the COX multivariate analysis, both overexpressed METTL3 and METTL14 were significantly associated with short overall survival (p < 0.05). Both METTL3 and METTL14 expressions and the m⁶ A amounts were significantly increased in HN6 (p < 0.05). Silencing of METTL3 and METTL14 in HN6 significantly inhibited cell proliferation (p < 0.01), but it failed to mitigate cell migration or invasion.

CONCLUSIONS

METTL3 and METTL14 are overexpressed in OSCC tissues and in the HN6 OSCC cell line that promotes cell proliferation. Overexpressed METTL3 or METTL14 is found to be an independent prognostic factor for short overall survival in patients with OSCC.

Deregulation of hsa_circ_0001971/miR-186 and hsa_circ_0001874/miR-296 signaling pathways promotes the proliferation of oral squamous carcinoma cells by synergistically activating SHP2/PLK1 signals

It has been demonstrated that circ_0001874 and circ_0001971 are potential biomarkers for the diagnosis of oral squamous carcinoma (OSCC). MiR-186 was reported to serve as a tumor suppressor in OSCC, and the down-regulation of miR-186 was reported to lead to higher expression of oncogenic factor SHP2 and the activation of growth promoting signaling. In this study, we aimed to explore the possible molecular role of circ_0001874 and circ_0001971 signaling in the pathogenesis of OSCC. RT-qPCR, Western blot, online bioinformatics tools and luciferase assay were utilized to study the molecular signaling pathways of circ_0001874 and circ_0001971. MTT assay and FCM assay were performed to investigate the synergistic effect of circ_0001971 and circ_0001874 on cell proliferation and apoptosis. By observing the effect of different miRNAs on the levels of circ_0001847 and circ_0001971, it was identified that circ_0001847 and circ_0001971 respectively sponged the expression of miR-296 and miR-186 via binding to these miRNAs. Also, SHP2 mRNA and PLK1 mRNA were respectively targeted by miR-186 and miR-296-5p. We also established two signaling pathways, i.e., circ_0001971/miR-186/SHP2 and circ_0001874/miR-296-5p/PLK1, and validated the synergistic effect of circ_0001971 and circ_0001874 via observing their positive effect on cell proliferation and negative effect on cell apoptosis. The expression of miR-186 and miR-296-5p was generally lower in saliva of OSCC patients compared with that in OLK patients, while the expression of miR-186 and miR-296-5p was specifically up-regulated in saliva of OSCC patients. In conclusion, the finding of this study demonstrated that the relative level of hsa_circ_0001971 and hsa_circ_0001874 were different in the saliva of OSCC patients and could be used as predictive biomarkers for the development of OSCC. Furthermore, oncogenic effects of hsa_circ_0001971 and hsa_circ_0001874 in the development of OSCC might be, at least partially, mediated by its downstream signaling pathways including hsa_circ_0001971/microRNA-186/SHP2 and hsa_circ_0001874/microRNA-297/PLK1.

Prognostic impact of lingual lymph node metastasis in patients with squamous cell carcinoma of the tongue: a retrospective study

Squamous cell carcinoma (SCC) of the tongue rarely metastasizes to the lingual lymph nodes (LLNs), which are inconstant nodes and often situated outside the areas of basic tongue tumor surgery. The current study evaluated the clinicopathological features and prognostic impact of LLN metastasis (LLNM), compared to that of cervical lymph node metastasis, in patients with tongue SCC. A total of 608 patients underwent radical surgery for tongue SCC at our department between January 2001 and December 2016. During neck dissection, we scrutinized and resected lateral LLNs, when present. Of the 128 patients with lymph node metastasis, 107 had cervical lymph node metastasis and 21 had both cervical lymph node metastasis and LLNM. Univariate analysis demonstrated that LLNM was significantly associated with the adverse features of cervical lymph node metastasis. The 5-year disease-specific survival (5y-DSS) was significantly lower in patients with LLNMs than in those without LLNMs (49.0% vs. 88.4%, P < 0.01). Moreover, Cox proportional hazards model analyses revealed that cervical lymph node metastasis at level IV or V and LLNM were independent prognostic factors for 5y-DSS. LLNM has a strong negative impact on survival in patients with tongue SCC. An advanced status of cervical lymph node metastasis may predict LLNM.

Expression and localisation of methylthioadenosine phosphorylase (MTAP) in oral squamous cell carcinoma and their significance in epithelial-to-mesenchymal transition

Methylthioadenosine phosphorylase (MTAP) is a rate-limiting enzyme in the methionine salvage pathway, which recycles one carbon unit that is lost during polyamine synthesis back into the methionine cycle. Although MTAP deficiency has been reported in various tumours, MTAP is overexpressed and might promote oncogenesis in other cancers, including prostate and colon cancer. Currently, little is known about the MTAP status of oral squamous cell carcinoma (OSCC). In this study, we immunohistochemically examined the expression of MTAP in surgically resected oral epithelial dysplasia (OED, n=7), carcinoma in situ (CIS) (n=16), and OSCC (n=118). In the normal epithelium, MTAP was only weakly expressed in the cytoplasm of the basal layer cells. In OED, CIS, and OSCC, MTAP was uniformly expressed in the cytoplasm of the dysplastic and cancer cells. In addition to cytoplasmic MTAP expression, 45 of 118 cases (38.1%) exhibited increased nuclear expression of MTAP in the cancer cells at the invasive front. Statistical analysis showed that the concomitant nuclear and cytoplasmic expression of MTAP was associated with a high budding score (p=0.0023); poor differentiation (p=0.0044); aggressive invasion patterns (p=0.0001); and features of epithelial-to-mesenchymal transition (EMT), such as loss of E-cadherin expression (p=0.0003) and upregulated expression of vimentin (p=0.0002), slug (p=0.0002), and laminin 5 (p<0.0001). High expression of protein arginine methyltransferase 1 or 5, the functions of which are reported to be inhibited in MTAP-deficient cancer, was associated with the concomitant nuclear and cytoplasmic expression of MTAP (p<0.0001). Concomitant nuclear and cytoplasmic expression of MTAP was marginally significantly associated with worse 5-year relapse-free survival (p=0.045). These findings suggest that MTAP not only plays a role in the oncogenesis of OSCC, but that it might also make it more aggressive by inducing EMT through its activity in the methionine salvage pathway.

Blocking circ-SCMH1 (hsa_circ_0011946) suppresses acquired DDP resistance of oral squamous cell carcinoma (OSCC) cells both in vitro and in vivo by sponging miR-338-3p and regulating LIN28B

Background

Circular RNAs (circRNAs) could participate in cis-dichlorodiammineplatinum (DDP) resistance of human cancers. However, circRNAs role in DDP resistance of oral squamous cell carcinoma (OSCC) progression remains largely undeveloped. Here, we attempted to explore the role of circ-SCMH1 (ID hsa_circ_0011946) in acquired DDP resistance.

Methods

Expression of circ-SCMH1, microRNA (miR)-338-3p and Lin-28 homolog B (LIN28B) was detected by real-time quantitative PCR and western blotting, and their interactions were confirmed by dual-luciferase reporter assay, RNA immunoprecipitation and RNA pull-down assay. DDP resistance was assessed by MTT assay, colony formation assay, flow cytometry, transwell assays, western blotting, and xenograft experiment. Transmission electron microscopic analysis, nanoparticle tracking analysis and western blotting confirmed the characterizations of extracellular vesicles (EVs).

Results

Circ-SCMH1 was upregulated in DDP-resistant OSCC tissues and cells (SCC-15/DDP and CAL-27/DDP). Circ-SCMH1 knockdown suppressed the half-maximal inhibitory concentration of DDP, colony formation, and migration/invasion in SCC-15/DDP and CAL-27/DDP cells, but promoted apoptosis rate and apoptotic proteins (Bax and cleaved-caspase-3) expression. However, silencing miR-338-3p abrogated above effects, and overexpressing miR-338-3p mimicked that. Similarly, miR-338-3p overexpression role could be counteracted by restoring LIN28B. Moreover, interfering circ-SCMH1 retarded tumor growth of SCC-15/DDP cells in vivo with DDP treatment or not. Mechanistically, circ-SCMH1 directly sponged miR-338-3p in regulating LIN28B, a target gene for miR-338-3p. Notably, circ-SCMH1 was an EVs cargo, and DDP-resistant OSCC cells-derived EVs could provoke circ-SCMH1 upregulation in parental cells.

Conclusion

Circ-SCMH1 contributes to chemoresistance of DDP-resistant OSCC cells partially via EVs secretion and circ-SCMH1/miR-338-3p/LIN28B axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02110-8.

Exploring the long noncoding RNAs-based biomarkers and pathogenesis of malignant transformation from dysplasia to oral squamous cell carcinoma by bioinformatics method

Long noncoding RNAs (lncRNAs) play an important role in many biological processes and carcinogenesis. We aimed to explore lncRNA-based pathogenesis, diagnostic biomarkers, and predictive factors of malignant transformation from dysplasia to oral squamous cell carcinoma (OSCC). Microarray data of GSE30784 consisting of 167 OSCC, 17 dysplasia, and 45 normal oral tissues were downloaded from the GEO database. The differentially expressed genes (DEGs) and lncRNAs between the three samples were identified using R, followed by lncRNA-mRNA coexpression and coregulation network analysis for the prediction of lncRNA target genes. Gene Ontology and Kyoto encydopedia of gene and genomes pathway analysis were performed to further characterize potential interactions. A total of 4462 DEGs and 76 differentially expressed lncRNAs were screened between the three groups, and 200 DEGs and only double homeobox A pseudogene 10 (DUXAP10) were screened among the three groups. A total of 1662 interactions of 46 lncRNAs and their coexpressed target genes were predicted, and 38 pairs of lncRNA-lncRNA coregulated 843 target genes. The coregulated target genes significantly enriched in antigen adaptive immune response, activation of phagocytosis receptor signaling, mast granule NF-κB inflammation, etc. Overall, lncRNAs were differentially expressed in OSCC and dysplasia. The target genes might play an important role in the carcinogenesis and development of OSCC. These results improve our understanding regarding the lncRNA-based pathogenesis and identify some potential targets for early diagnosis of malignant transformation from dysplasia to OSCC.

lncRNA LINC01296 Promotes Oral Squamous Cell Carcinoma Development by Binding with SRSF1

Objective

Oral squamous cell carcinoma (OSCC) is the most common malignant tumor of the head and neck, with strong local invasiveness and cervical lymph node metastasis. The purpose of this study was to investigate the role of LINC01296 in oral squamous cell carcinoma and its possible mechanism.

Materials and Methods

GEPAI database analysis and clinical samples were used to detect the expression of LINC01296 in head and neck cancer. In vivo experiment, MTT, clone formation assay, and transwell were used to detect the proliferation, migration, and invasion of oral squamous cell carcinoma. The effect of LINC01296 on EMT was detected by western blot and qRT-PCR to measure the expression of epithelial and mesenchymal phenotypic markers. BALB/c nude mice were used to carry out in vitro treatment experiment. In terms of mechanism, the binding relationship between LINC01296 and SRSF1 was predicted and verified by the RBPDB database and RNA pull-down assay.

Results

LINC01296 was highly expressed in clinical samples and cell lines of oral squamous cell carcinoma. Overexpression of LINC01296 promoted the proliferation, invasion, and migration of oral squamous cell carcinoma cells and accelerated the formation of xenografts, while silencing LINC01296 inhibited tumor progression. In mechanism, LINC01296 plays a tumor-promoting role by binding to SRSF1 protein.

Conclusion

LINC01296 promotes malignant lesions in oral squamous cell carcinoma by binding to SRSF1 protein, which provides important experimental data and theoretical basis for the prevention, diagnosis, and treatment of oral squamous cell carcinoma.

Long non-coding RNAs in head and neck squamous cell carcinoma: Diagnostic biomarkers, targeted therapies, and prognostic roles

At present, emerging evidence shows that non-coding RNAs (ncRNAs) play crucial roles for development of multiple tumors. Amongst these ncRNAs, long non-coding RNAs (lncRNAs) play prominent roles in physiological and pathological processes. LncRNAs are RNA transcripts larger than 200 nucleotides and have been shown to serve important regulatory roles in different types of cancer via interactions with DNA, RNA and proteins. Head and neck squamous cell carcinoma (HNSCC) is one of the most malignant tumors with low survival rates in advanced stages. Recently, lncRNAs have been demonstrated to be involved in a wide range of biological processes, including proliferation, metastasis, and prognosis of HNSCC. Therefore, this review describes molecular mechanisms of up- or down-regulation of lncRNAs and expounds their functions in pathology and clinical practices in HNSCC. It also highlights their potential clinical applications as biomarkers for the diagnosis, prognosis, and treatment of HNSCC. However, studies on lncRNAs are still not comprehensive, and more investigations are needed in the future.

Identification of oral squamous cell carcinoma markers MUC2 and SPRR1B downstream of TANGO

PURPOSE

Transport and Golgi organization protein 1 (TANGO) promotes angiogenesis and lymphangiogenesis in oral squamous cell carcinoma (OSCC). To elucidate the underlying mechanisms, this study aims to identify and characterize elements downstream of TANGO that mediate its involvement in OSCC.

METHODS

In this study, microarray analysis compared gene expression between control and TANGO-repressed HSC3 cells. Protein expression in 213 OSCC tissue samples was analyzed immunohistochemically.

RESULTS

TANGO repression decreased or increased expression of Mucin 20 (MUC20) and small proline-rich protein 1B (SPRR1B), respectively. MUC20 increased the growth and invasiveness of OSCC cells via altered matrix metalloproteinase (MMP)-2 and E-cadherin expression and c-met phosphorylation. MUC20 induced angiogenesis and lymphangiogenesis by activating vascular endothelial growth factors A and C. In well-differentiated OSCC, SPRR1B expression was high (P = 0.0091) and correlated with keratinization markers and promoted proliferation by inducing mitogen-activated protein kinase p38 phosphorylation. MUC20 expression correlated significantly with clinical stage (P = 0.0024), lymph node metastasis (P = 0.0036), and number of blood and lymph vessels (P < 0.0001). MUC20-expressing cases had a significantly worse prognosis than non-expressing cases (P < 0.0001).

CONCLUSION

MUC20 and SPRR1B located downstream of TANGO may be useful molecular markers for OSCC.

Prognostic value of the PIK3CA, AKT, and PTEN mutations in oral squamous cell carcinoma: literature review

Over 260,000 (2013) new oral squamous cell carcinoma (OSCC) cases are reported annually worldwide. Despite development in OSCC management, the outcome is still unsatisfactory. Identification of new molecular markers may be of use in prevention, prognosis, and choice of an appropriate therapy. The intracellular molecular signalling pathway of phosphatidyl-inositol-3-kinase is involved in the process of cell growth, differentiation, migration, and survival. The main components of this pathway: PIK3CA (phosphatidylinositol-4,5-bisphosphate-3-kinase catalytic subunit α), PTEN (phosphatase and tensin homologue deleted on chromosome 10), and AKT (serine-threonine kinase) are potential objects of research when introducing new therapeutic agents. The aim of this paper is to evaluate the PIK3CA, PTEN, and AKT gene mutations as prognostic factors in OSCC and to describe their role in aggressive disease progression. This is crucial for oral cancer biology understanding and for indicating which direction new clinical treatments should take.

Any Role of PIK3CA and PTEN Biomarkers in the Prognosis in Oral Squamous Cell Carcinoma?

Oral squamous cell carcinoma (OSCC) accounts for 95% of the lesions in the oral cavity. Despite development in OSCC management, the outcome is still unsatisfactory. Identification of new therapies in OSCC is urgently needed. One objective of such treatment may be a signaling pathway of phosphatidylinositol 3-kinase. The study group included 92 patients treated for OSCC at the University Clinical Centre in Gdańsk, Poland. Study was performed on formalin-fixed paraffin-embedded samples from primary OSCC. Phosphatidylinositol-4,5-bisphosphate 3-kinase (PIK3CA) and phosphatase and tensin homolog encoded on chromosome 10 (PTEN) protein expression was assessed by immunohistochemistry (IHC). PIK3CA gene copy number was analyzed using chromogenic and silver in situ hybridization where molecular probes are marked by chromogens and silver ions. PIK3CA IHC H-score ≥ 70 was found in 51.65% patients, and loss of PTEN protein was noticed in 31.46% cases. PIK3CA amplification was detected in 5 tumors. In the case of PTEN protein expression, there was an inverse correlation with the T stage of the primary tumor (r = -0.243) and positive correlation with a 5-year survival (r = 0.235). The number of copies of the PIK3CA gene was associated with the tumor grading (r = 0.208). The present study shows that loss of PTEN protein and the grading (p = 0.040), distant metastases (p = 0.033), smoking (p = 0.016), and alcohol abuse (p = 0.042) were prognostic factors for the survival of patients with OSCC. In contrast, the presence of amplification and OSCC on the floor of the mouth resulted in a nearly six-fold increase in the risk of shortening survival (p = 0.037). Our finding suggests a potential prognostic significance of PTEN loss and PIK3CA amplification in OSCC. Future studies are needed to confirm our results.

Cyclin G2 Inhibits Oral Squamous Cell Carcinoma Growth and Metastasis by Binding to IGFBP3 and Regulating the FAK-SRC-STAT Signaling Pathway

The cell cycle protein cyclin G2 is considered a tumor suppressor. However, its regulatory effects and potential mechanisms in oral cancers are not well understood. This study aimed to investigate the effect of cyclin G2 on oral squamous cell carcinoma (OSCC). The data from 80 patients with OSCC were utilized to predict the abnormal expression of cyclin G2. The proliferation and metastasis were determined by a cell counting Kit-8 assay, flow cytometry, a wound-healing assay, and a cell invasion assay. The expression of key proteins and genes associated with the cyclin G2 signaling pathways was determined by western blotting and real-time PCR, respectively. The orthotopic nude mice model was established by a mouth injection of SCC9 cells overexpressing cyclin G2. We showed that the low level of cyclin G2 in OSCC, which is negatively correlated with clinical staging, was a negative prognostic factor for the disease. We also found that cyclin G2 inhibited the proliferation, metastasis, and blocked the cell cycle at G1/S of OSCC cells, suggesting that cyclin G2 has an inhibitory effect in OSCC. Mechanistically, cyclin G2 inhibited the growth and metastasis of OSCC by binding to insulin-like growth factor binding protein 3 (IGFBP3) and regulating the focal adhesion kinase (FAK) -SRC-STAT signal transduction pathway. Cyclin G2 competed with integrin to bind to IGFBP3; the binding between integrin and IGFBP3 was reduced after cyclin G2 overexpression, thereby inhibiting the phosphorylation of FAK and SRC. These results showed that cyclin G2 inhibited the progression of OSCC by interacting with IGFBP3 and that it may be a new target for OSCC treatment.

Ras Pathways on Prox1 and Lymphangiogenesis: Insights for Therapeutics

Over the past couple of decades, lymphatics research has accelerated and gained a much-needed recognition in pathophysiology. As the lymphatic system plays heavy roles in interstitial fluid drainage, immune surveillance and lipid absorption, the ablation or excessive growth of this vasculature could be associated with many complications, from lymphedema to metastasis. Despite their growing importance in cancer, few anti-lymphangiogenic therapies exist today, as they have yet to pass phase 3 clinical trials and acquire FDA approval. As such, many studies are being done to better define the signaling pathways that govern lymphangiogenesis, in hopes of developing new therapeutic approaches to inhibit or stimulate this process. This review will cover our current understanding of the Ras signaling pathways and their interactions with Prox1, the master transcriptional switch involved in specifying lymphatic endothelial cell fate and lymphangiogenesis, in hopes of providing insights to lymphangiogenesis-based therapies.

Dental Calculus as a Potential Biosource for Human Papillomavirus Detection in Oral Squamous Cell Carcinoma

OBJECTIVE

The infection of human papillomaviruses (HPVs) plays a role in the development of oral squamous cell carcinoma (OSCC). A poor oral hygiene and dental calculus may cause the infection to persist. Therefore, this study aimed to assess whether this dental calculus could serve as a potential biosource in early detection of HPVs in patients with OSCC.

METHODS

DNA was isolated from the dental calculus of people diagnosed with OSCC, and MY09/11 primer set was used to detect the presence of HPV. The positive samples were further sequenced and aligned using megablast NCBI BLAST tool to identify the HPV genotype.

RESULTS

Electrophoresis examination showed that 4 of 14 samples collected (29%) had a clear single band, of which three had 97% to 99% similarity to a high-risk genotype HPV-58. Meanwhile, the other sample had 99% similarity to an unclassified papillomaviridae.

CONCLUSION

Dental calculus is a promising source of HPV in oral cavity and could be used as a biomarker for early detection.

Differential expression of programmed death-1 and its ligand, programmed death ligand-1 in oral squamous cell carcinoma with and without oral submucous fibrosis

OBJECTIVE

The aim of our study was to investigate the expression of programmed death ligand-1 (PD-L1)/programmed death-1 (PD-1) between oral squamous cell carcinoma (OSCC) patients with and without oral submucous fibrosis (OSF), and its correlation with clinic-pathologic features and its prognostic value.

METHODS

PD-L1 and PD-1 expression was evaluated by immunohistochemical staining, double immunofluorescent staining and real-time PCR, and the correlation of PD-L1/PD-1 expression with clinical outcome was assessed.

RESULTS

The level of PD-L1 expression was significantly higher in OSCC with OSF than in OSCC without OSF (p = 0.006). Moreover, PD-L1 expression was strongly correlated with lymph node metastasis (p = 0.016), and advanced tumor stage (p = 0.030). Increased PD-L1 expression was positively correlated with the incidence of OSCC with OSF (p = 0.006, p = 0.008, respectively). PD-L1 expression was an independent marker of unfavorable prognosis (p = 0.035, p = 0.048, respectively). High PD-L1 expression had a significantly worse outcome in OSCC patients with OSF (p = 0.014). Double immunofluorescent staining showed that OSCC with OSF were more strongly expressed both PD-L1 and PD-1 than OSCC without OSF. Moreover, the expression of PD-L1 were upregulated in OSCC tissues than normal control (p = 0.0422), and both PD-L1 and PD-1 was significantly higher in OSCC with OSF than OSCC without OSF tissues (p = 0.0043 and, p = 0.0012, respectively).

CONCLUSIONS

The present study suggested that PD-L1 may be an unfavorable indicator for prognosis. PD-L1/PD-1 signaling might play an important role in the malignant transformation of OSF, and targeting PD-L1/PD-1 signaling may be a new therapeutic strategy for OSCC, especially in OSCC patients with OSF.

Circ_0000140 restrains the proliferation, metastasis and glycolysis metabolism of oral squamous cell carcinoma through upregulating CDC73 via sponging miR-182-5p

Background

Oral squamous cell carcinoma (OSCC) is a more common cancer in the world. Emerging evidence suggests that circular RNAs (circRNAs) participate in the progression of OSCC. However, the role of circ_0000140 in OSCC is still unknown.

Methods

The expression of circ_0000140 and microRNA-182-5p (miR-182-5p) were assessed by quantitative real-time polymerase chain reaction (qRT-PCR). Also, cell proliferation, migration and invasion were measured by colony formation and transwell assays, respectively. Western blot (WB) analysis was used to test the levels of proliferation, metastasis and glycolysis metabolism-related proteins as well as cell division cycle 73 (CDC73) protein. Further, the extracellular acidification rate (ECAR) of cells was detected by the Seahorse XF Extracellular Flux Analyzer. The lactate acid level of cells was tested by Lactate Assay Kit. Moreover, dual-luciferase reporter was used to verify the interaction between miR-182-3p and circ_0000140 or CDC73, and RNA immunoprecipitation (RIP) assay was employed to further confirm the relationship between miR-182-3p and circ_0000140. In addition, mice xenograft models were built to measure the effect of circ_0000140 on OSCC tumor growth in vivo.

Results

Circ_0000140 was lowly expressed in OSCC, and its overexpression hindered proliferation, migration, invasion and glycolysis metabolism in OSCC cells. MiR-182-5p could be sponged by circ_0000140, and its mimic could invert the suppression of circ_0000140 overexpression on OSCC progression. CDC73 could be targeted by miR-182-3p, and its silencing could reverse the inhibition of miR-182-3p inhibitor on OSCC progression. Further, overexpressed circ_0000140 reduced the OSCC tumor growth in vivo.

Conclusions

Circ_0000140 might play an anti-cancer role in OSCC, which provided a novel target for clinical therapy of OSCC.

Head and Neck Cancer Metastasis and the Effect of the Local Soluble Factors, from the Microenvironment, on Signalling Pathways: Is It All about the Akt?

The signalling pathways involved in metastasis of oral adenoid cancer cells (TYS) in response to cancer-associated fibroblasts (COM D24) and normal oral mucosal fibroblasts (MM1) was examined. Metastatic cell behaviour was observed by cell-scatter, 3-D-collagen gel migration, and 3-D-spheroid invasion assays. Akt (v-Akt murine thymoma viral oncogene), MAPK(Mitogen activated protein kinase), EGFR (Epidermal growth factor receptor), TGFβRI (Transforming growth factor beta receptor 1), and CXCR4 (C-X-C chemokine receptor 4) inhibitors were used to identify the signalling pathways involved. Signalling pathway protein expression and activation were assessed by SDS-PAGE and Western blotting. COM-CM (conditioned medium from COM D24 cells) and MM1-CM (conditioned medium from MM1 cells) stimulated cancer cell scattering, which was blocked only by the Akt inhibitor. COM-CM-induced scattered cancer cells showed higher levels of Akt phosphorylation than the negative control and MM1-CM. Migration and invasion of TYS cells into collagen gels from the spheroids was stimulated by CM from both fibroblast cell lines, compared to the negative control. COM cells stimulated TYS invasion into the collagen more than MM1 and the control. Akt and EGFR inhibitors effectively blocked CM and COM cell-induced invasion. Akt-silenced cancer cells were not stimulated to migrate and invade by fibroblast-CM and did not survive the addition of an EGFR inhibitor. This suggests that CAFs stimulate head and neck cancer cell migration and invasion in an Akt- dependent manner. Akt may represent a potential target for inhibitor design to treat metastatic head and neck cancer.

Lycopene Inhibits Epithelial-Mesenchymal Transition and Promotes Apoptosis in Oral Cancer via PI3K/AKT/m-TOR Signal Pathway

Background

Oral cancer (OC) is one of the most common cancers around the world. Despite the progress in treatment, the prognosis of OC remains poor, especially for patients with advanced diseases. It urges the development of novel therapeutic options against OC. Lycopene (LYC) is an antioxidant with chemoprotective properties against cancer. However, little is known about the mechanisms underlying the protective role of LYC in OC tumorigenesis.

Methods

In this study, we investigated the anti-cancer effect of LYC on the progression of OC in vitro and in vivo and explored the underlying mechanisms involved in this process.

Results

LYC inhibited OC cell proliferation, migration, invasion, apoptosis, and xenograft tumor growth in a dose-dependent manner. Furthermore, we found that LYC might inhibit epithelial-mesenchymal transition and induce apoptosis in OC cells by deactivating the PI3K/AKT/m-TOR signaling through increasing the levels of E-cadherin and Bax and downregulating N-cadherin, p-PI3K, p-AKT, p-m-TOR, and bcl-2.

Conclusion

We reported for the first time that LYC exhibited anti-cancer effects on OC development both in vitro and in vivo via regulating EMT process and apoptosis. These findings provide support for the potential clinical use of LYC in OC treatment.

Repertoire of peripheral T cells in patients with oral squamous cell carcinoma

BACKGROUND

The establishment of adaptive immune responses to neoplasms involves not only the tumour tissue, but also the peripheral blood. We aimed to conduct a preliminary exploration to understand the immune response of T lymphocytes of peripheral blood mononuclear cells (PBMC-Ts) in oral squamous cell carcinoma (OSCC).

METHODS

A total of 103 blood samples from OSCC patients and 18 blood samples from healthy donors (HD) were analysed by flow cytometry.

RESULTS

Compared to those in HD, a series of unique features of PBMC-Ts were observed in OSCC patients including a significant increase in CD4+ T cells, a shift from naïve to memory/effector phenotype, an increased frequency of exhausted phenotypes (programmed death-1 [PD-1], T cell Ig and mucin protein-3 [Tim-3] and Tregs), an abundance of Th17s and Tc17s and an imbalance in Th17/Tc17 and Th17/Treg ratios. Furthermore, in OSCC patients, we also found that CD4+ T cells were significantly increased in patients with larger tumours than smaller tumours, memory/effector phenotype and exhausted phenotypes were significantly associated with advanced clinical stage and lymph node metastasis, and the Th17/Treg ratio was associated with early clinical stage and no lymph node metastasis.

CONCLUSION

PBMC-Ts may be involved in the development and progression of OSCC, which suggested to be a manifestation of an immune response between host and tumour neoantigens.

Role and Mechanism of LIF in Oral Squamous Cell Carcinoma Progression

Background: Metastasis is a severe problem in patients with oral squamous cell carcinoma (OSCC), which is the fifth most common cancer worldwide. Leukemia inhibitory factor (LIF) has been studied in different cancers, while the role of LIF in OSCC remains unclear. Methods: LIF expression was detected in 100 OSCC samples by immunohistochemistry. Effects of LIF on cell motility were evaluated in OSCC cell lines. High-throughput microarray analysis was also conducted. The correlation between LIF and the downstream effector was analyzed by real-time quantitative reverse transcription PCR. Results: Patients with OSCC who had lymph node metastasis or advanced cancer stages showed high LIF expression. OSCC patients with higher LIF expression, advanced stage, large tumor size, or lymph node metastasis had significantly shorter overall survival. LIF regulated cancer cell motilities through outside-in signaling. The inhibin beta A subunit (INHBA) gene was identified as a crucial downstream effector of LIF-promoted OSCC progression and restored migration and invasion abilities in LIF knockdown transfectants. Conclusion: LIF enhances regional lymphatic spread, thus leading to an advanced cancer stage. Regulation of LIF downstream molecules such as INHBA inhibits the invasion or migration ability of cancer cells. Thus, LIF can be a potential target in preventing cancer metastasis and spread.

The repertoire of tumor-infiltrating lymphocytes within the microenvironment of oral squamous cell carcinoma reveals immune dysfunction

BACKGROUND

The role of tumor-infiltrating lymphocytes (TILs) in the immune remodeling of tumor microenvironments (TME) in oral squamous cell carcinoma (OSCC) remains controversial. In this study, we pursued a comprehensive characterization of the repertoire of TILs and then analyzed its clinical significance and potential prognostic value.

METHODS

Fresh tumor tissue samples and peripheral blood from 83 OSCC patients were collected to comprehensively characterize the phenotypes and frequencies of TILs by flow cytometry. Archived paraffin-embedded tissues derived from 159 OSCC patients were analyzed by immunohistochemistry to further assess the TIL repertoire. The clinical significance of TILs and their potential prognostic value were further analyzed.

RESULTS

A series of unique features of TILs were observed. IL-17 was highly expressed in betel nut chewers, and CD20 was abundantly expressed in patients who did not drink alcohol; high expression of CD138, PD-L1, and Foxp3 was associated with poor prognosis. The Th17/Treg ratio was an independent prognostic factor for patient survival with greater predictive accuracy for overall survival.

CONCLUSIONS

Our results suggest an antigen-driven immune response; however, the immune dysfunction within the microenvironment in OSCC and the Th17/Treg balance may play important roles in the modulation of antitumor immunity.

Hsa_circ_0086414 Might Be a Diagnostic Biomarker of Oral Squamous Cell Carcinoma

Background

Circular RNAs (circRNAs), a newly-discovered class of non-coding RNAs, have a significant role in the progression of cancers, but the effect of hsa_circ_0086414 in human oral squamous cell carcinoma (OSCC) is still unclear.

Material/Methods

The circRNAs expression profile in OSCC tissue samples was assessed by high-throughput sequencing. The hsa_circ_0086414 expression level in 55 paired OSCC tissue samples and 2 kinds of OSCC cells was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). Additionally, the correlation between the hsa_circ_0086414 expression and clinicopathological characteristics of individuals with OSCC was studied. We used receiver operating characteristic (ROC) curves to observe the hsa_circ_0086414 value of diagnosis in OSCC. The network of hsa_circ_0086414-miRNAs-mRNAs was constructed. Gene Ontology (GO), Disease Oncology (DO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were carried out based on sequencing data and bioinformatics predictions.

Results

Hsa_circ_0086414 expression in OSCC tissue samples and OSCC cells was first discovered to be significantly downregulated compared with the adjacent healthy tissues (AHTs) and normal (HaCaT) cells, respectively. Moreover, its expression level was significantly correlated with stage in TNM, size of tumor, and lymph node metastasis. The area below the ROC curve was 0.749. Hsa_circ_0086414-miRNAs-mRNAs network analysis and GO, DO, and KEGG analyses all demonstrated that hsa_circ_0086414 is correlated with cancer progression to a certain extent.

Conclusions

We discovered that hsa_circ_0086414 might be an essential diagnostic biomarker in OSCC. Furthermore, hsa_circ_0086414 could be a target for OSCC therapy.

TROP2 increases growth and metastasis of human oral squamous cell carcinoma through activation of the PI3K/Akt signaling pathway

Most malignant neoplasms of the oral cavity are oral squamous cell carcinoma (OSCC), which is a type of highly malignant tumor with a propensity for forming distant metastases. Trophoblast cell surface antigen 2 (TROP2) is a transmembrane protein that is overexpressed in several types of tumor cells, although its role and regulatory mechanism in OSCC have not been determined. The aim of the present study was to examine the effects of TROP2 in human OSCC cell lines. The present study demonstrated that TROP2 protein expression was upregulated in OSCC cell lines. Transfection of short hairpin RNA (shRNA) targeting TROP2 (sh‑TROP2) reduced cell proliferation, migration and invasion of OSCC cell lines, whereas overexpression of TROP2 increased proliferation, migration and invasion. sh‑TROP2 transfection in OSCC cell lines inhibited tumor growth in OSCC mouse models. Furthermore, TROP2 expression activated the phosphoinositide 3‑kinase (PI3K)/Akt signaling pathway in human OSCC cells. These results suggest that TROP2 induces cell growth, migration and invasion through activation of the PI3K/Akt signaling pathway in OSCC cells.

Relevance of Neurotrophin Receptors CD271 and TrkC for Prognosis, Migration, and Proliferation in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and often has a poor prognosis. The present study investigated the role of the low affinity nerve growth factor receptor CD271 as a putative therapy target in HNSCC. Neurotrophins that bind to CD271 also have a high affinity for the tropomyosin receptor kinase family (Trk), consisting of TrkA, TrkB, and TrkC, which must also be considered in addition to CD271. A retrospective study and functional in vitro cell line tests (migration assay and cell sorting) were conducted in order to evaluate the relevance of CD271 expression alone and with regard to Trk expression. CD271 and Trks were heterogeneously expressed in human HNSCC. The vast majority of tumors exhibited CD271 and TrkA, whereas only half of the tumors expressed TrkB and TrkC. High expression of CD271-positive cells predicted a bad clinical outcome of patients with HNSCC and was associated with distant metastases. However, the human carcinomas that also expressed TrkC had a reduced correlation with distant metastases and better survival rates. In vitro, CD271 expression marked a subpopulation with higher proliferation rates, but proliferation was lower in tumor cells that co-expressed CD271 and TrkC. The CD271 inhibitor LM11A 31 suppressed cell motility in vitro. However, neither TrkA nor TrkB expression were linked to prognosis or cell proliferation. We conclude that CD271 is a promising candidate that provides prognostic information for HNSCC and could be a putative target for HNSCC treatment.

Regulation of collagen type XVII expression by miR203a-3p in oral squamous cell carcinoma cells

Collagen type XVII (COL17) is expressed in various tissues and its aberrant expression is associated with tumour progression. In this study, we investigated the regulation of COL17 expression in oral squamous cell carcinoma (OSCC) using the cell lines NA, SAS, Ca9-22, and Sa3. COL17 was induced upon p53 activation by cisplatin in SAS; however, this effect was more limited in NA and hardly in Ca9-22 and Sa3, with mutated p53. Moreover, COL17 was found to be regulated by miR203a-3p in all cell lines. Our data suggest that COL17 expression in OSCC cell lines is regulated by p53 and miR203a-3p.

Silencing of LINC01116 suppresses the development of oral squamous cell carcinoma by up-regulating microRNA-136 to inhibit FN1

Background

Oral squamous cell carcinoma (OSCC), one of the most common cancers worldwide with a high mortality rate, is accompanied by poor prognosis, highlighting the significance of early diagnosis and effective treatment. Long non-coding RNAs (lncRNAs) have been linked with the development and progression of various cancers. In this study, aberrantly expressed lncRNA LINC01116, microRNA-136 (miR-136), and fibronectin1 (FN1) were identified in OSCC using a microarray analysis. Therefore, this study aimed to investigate the role of LINC01116/miR-136/FN1 regulatory axis in OSCC.

Methods

The gain-of-function and loss-of-function experiments in vitro were performed to alter the expression of LINC01116 and miR-136 in OSCC cells to elucidate their effects on cellular processes, including epithelial-mesenchymal transition (EMT), viability, invasion, and migration. In addition, the interaction among LINC01116, miR-136, and FN1 was identified. Additionally, the tumorigenicity and lymph node metastasis (LNM) affected by LINC01116 were observed through xenograft tumor in nude mice.

Results

LINC01116 and FN1 were abundant in both OSCC tissues and cells, while miR-136 was poorly expressed. LINC01116 could competitively bind to miR-136, which targets and negatively regulates FN1. Moreover, in response to LINC01116 silencing or miR-136 over-expression, OSCC cells exhibited diminished EMT process and inhibited cell viability, invasion, and migration in vitro, coupling with impaired tumorigenicity and LNM in vivo.

Conclusion

The fundamental findings in this study collectively demonstrate that LINC01116 silencing may inhibit the progression of OSCC via the miR-136-mediated FN1 inhibition, highlighting a promising therapeutic strategy for OSCC treatment.

miRNAs expression of oral squamous cell carcinoma patients: Validation of two putative biomarkers

microRNA expression patterns have provided new directions in the search of biomarkers with prognostic value and even in the search of novel therapeutic targets for several neoplasms. Specifically, miRNAs profiling in oral squamous cell carcinoma (OSCC) represents a web of intrigue in the study of oral carcinogenesis. The objective of the present study was twofold:The first study phase comprised case-control groups: A) 8 OSCC-affected patients and 8 healthy controls. Microarray technology (Affymetrix miRNA Array Plate 4.1) was used for miRNAs expression profile. Deregulated miRNAs were studied using Diana Tools miRPath 3.0 to associate miRNA targets with molecular pathways via Kyoto Encyclopedia of Genes and Genomes (KEGG). In a second phase, 2 miRNAs chosen for the subsequent RT-qPCR validation were studied in a second OSSC cohort (n = 8).Microarray analysis identified 80 deregulated miRNAs (35 over-expressed and 45 under-expressed). Two miRNAs (miR-497-5p and miR-4417) were chosen for further validation via RT-qPCR. Prognostic analysis did not ascertain relevant relation between miR-497-5p or miR-4417 expression and clinical or pathological parameters, except high miR-4417 in the case of nodular affectation (P = .035) and diminished miR-497-5p radiotherapy-treated patients (P = .05). KEGG analysis revealed that deregulated miRNAs were implicated in several biological pathways such as Proteoglycans in cancer.Our data suggest an altered miRNAs profiling in OSCC-affected patients. We have verified the altered expression of miR-497-5p and miR-4417 in OSCC samples and related the deregulated miRNAs with the 'proteoglycans in cancer' pathway. Further longitudinal studies with large samples are warranted to confirm the present findings.

Distinct Expression and Clinical Significance of Zinc Finger AN-1-Type Containing 4 in Oral Squamous Cell Carcinomas

Zinc finger AN1-type containing 4 (ZFAND4) has emerged as a promising prognostic marker and predictor of metastasis for patients with oral squamous cell carcinoma (OSCC). However, further validation is fundamental before clinical implementation. Hence, this study evaluated the expression pattern of ZFAND4 protein expression by immunohistochemistry using an independent cohort of 125 patients with OSCC, and correlations with the clinicopathologic parameters and disease outcome. Remarkably, ZFAND4 expression, while negligible in normal epithelium, exhibited two distinct expression patterns in tumors that did not overlap. A gross granular staining was characteristic of the undifferentiated cells at the invasive front of tumors, whereas the most differentiated cells located at the center of the tumor nests showed diffuse non-granular staining. ZFAND4 staining was higher in undifferentiated than in differentiated areas of tumors. High ZFAND4 expression in differentiated cells was significantly associated to well-differentiated (p = 0.04) and non-recurrent tumors (p = 0.04), whereas ZFAND4 expression in undifferentiated cells correlated with tumor location (p = 0.005). No correlations between the ZFAND4 expression and patient survival were found. These data question the clinical relevance of ZFAND4 expression as a prognostic biomarker in OSCC, and also reveal distinct ZFAND4 expression patterns depending on the differentiation areas of tumors that should be evaluated separately.

Ki-67 is an independent prognostic marker for the recurrence and relapse of oral squamous cell carcinoma

As a nuclear and nucleolar protein, proliferation marker protein Ki-67 (Ki-67) serves a vital role in tumorigenesis due to its positive correlation with tumor proliferation. High expression of Ki-67 in the cell cycle from the G₁ to M phase makes it a potential biomarker for certain tumors and useful for selecting medical treatment. However, the diagnostic value of Ki-67 in oral squamous cell carcinoma (OSCC) has not been fully evaluated. In the present study, the objective was the elucidation of the prognostic value of Ki-67 in a large number of OSCC patients. Ki-67 expression was detected by immunohistochemical staining methods in 298 OSCC specimens and 98 tumor-free oral mucosa specimens (62 dysplasia mucosa and 36 normal mucosa), acquired from Nanjing Stomatological Hospital, Medical School of Nanjing University (Nanjing, China). Expression of Ki-67 in normal tissues, dysplasia tissues and OSCC tissues was compared. Associations between Ki-67 expression and clinicopathological parameters were analyzed by χ² test. Kaplan-Meier survival curves and Cox progression analysis were used to assess the diagnostic value of Ki-67 for OSCC. The results showed that Ki-67 expression was higher in OSCC tissues than in tumor-free tissues and that it increased with the progression of dysplasia in oral mucosa tissues. In addition, patients with high Ki-67 expression had a worse clinical outcome, including poor tumor differentiation (P=0.001), increased positive lymph node metastasis (P=0.006) and increased worst pattern of invasion type (P<0.0001). Kaplan-Meier survival analysis demonstrated that higher Ki-67 expression was associated with poorer overall survival (OS) (P=0.035), recurrence-free survival (RFS) (P=0.017), metastasis-free survival (MFS) (P=0.032) and disease-free survival (DFS) (P=0.018) times. Additional multivariate analysis demonstrated that Ki-67 expression was negatively associated with OS, DFS, RFS and MFS. In conclusion, Ki-67 overexpression is associated with the progression of OSCC and serves as an independent prognostic factor for OSCC patients.

Eukaryotic translation initiation factor 5A-2 involves in doxorubicin-induced epithelial-mesenchymal transition in oral squamous cell carcinoma cells

Background: Epithelial-mesenchymal transition (EMT) is considered to be vital during chemotherapy resistance in oral squamous cell carcinoma (OSCC). Recently, eukaryotic initiation factor 5A-2 (eIF5A-2), a potential oncogene, has been reported to be involved in chemotherapy resistance in human cancers.

Materials and Methods: N1-guanyl-1,7-diaminoheptane (GC7, a novel eIF5A-2 inhibitor) or siRNA on responses to doxorubicin were examined in OSCC cells. Cytotoxicity and protein expression were evaluated by CCK-8 and EdU incorporation assay and western blotting. Tca8113 cells were used for establishment and treatment of tumor xenografts in vivo.

Results: Low concentration of GC7 (5μΜ) significantly enhanced doxorubicin cytotoxicity in both epithelial phenotype OSCC cells (Cal27) and mesenchymal phenotype OSCC cells (HN30 and Tca8113). EMT process promoted by doxorubicin in Cal27 cells could be reversed by GC7. Additionally, GC7 induced mesenchymal-epithelial transition (MET) in HN30 and Tca8113 cells. Silencing of eIF5A-2 by specific siRNA exhibited the similar effects. The synergistic cytotoxicity of doxorubicin/GC7 combination was not induced in Twist-1, an EMT driving factor, silenced Cal27, HN30, and Tca8113 cells. GC7 also synergized doxorubicin to inhibit tumor growth in vivo treatment.

Conclusions: Our study strongly proved that combined treatment with GC7 may boost the therapeutic effect of doxorubicin in OSCC by inhibiting the EMT.

Downregulation of DHRS9 is associated with poor prognosis in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) has a high potential for local invasion and nodal metastasis. Therefore, early detection and elucidation of the detailed molecular mechanisms underlying OSCC are essential. Dehydrogenase/reductase member 9 (DHRS9) is downregulated in recurrent OSCC. Although DHRS9 is reported to act as a tumour suppressor in several malignancies, its expression in OSCC cells is unknown. In this study, we examined DHRS9 expression immunohistochemically in specimens from a sample of 98 OSCC patients. Reduced DHRS9 expression was observed in 68 of 98 patients (69.4%) with OSCC. A significant association was found between low DHRS9 expression and local progression (T factor) (p = 0.0135). Furthermore, patients with low DHRS9 expression had a significantly poorer prognosis than those with high DHRS9 expression (p = 0.0443). In multivariate analysis using the Cox proportional hazards model, decreased DHRS9 expression strongly correlated with worse prognosis. The study findings suggest that DHRS9 might be a useful diagnostic and prognostic marker for OSCC.

Hallmarks of Cancer-Related Newly Prognostic Factors of Oral Squamous Cell Carcinoma

Head and neck cancer, including oral squamous cell carcinoma (OSCC), is the sixth leading malignancy worldwide. OSCC is an aggressive tumor and its prognosis has exhibited little improvement in the last three decades. Comprehensive elucidation of OSCC's molecular mechanism is imperative for early detection and treatment, improving patient survival. Based on broadly accepted notions, OSCC arises from multiple genetic alterations caused by chronic exposure to carcinogens. In 2011, research revealed 10 key alterations fundamental to cancer cell development: sustaining proliferative signaling, evading growth suppressors, avoiding immune destruction, activating invasion and metastasis, tumor-promoting inflammation, enabling replicative immortality, inducing angiogenesis, genome instability and mutation, resisting cell death, and deregulating energetics. This review describes molecular pathological findings on conventional and novel hallmarks of OSCC prognostic factors. In addition, the review summarizes the functions and roles of several molecules as novel OSCC prognosticators.

Flubendazole and mebendazole impair migration and epithelial to mesenchymal transition in oral cell lines

Benzimidazole anthelmintics flubendazole and mebendazole are microtubule-targeting drugs that showed considerable anti-cancer activity in different preclinical models. In this study, the effects of flubendazole and mebendazole on proliferation, migration and cadherin switching were studied in a panel of oral cell lines in vitro. Both compounds reduced the viability of the PE/CA-PJ15 and H376 oral squamous carcinoma cells and of the premalignant oral keratinocytes DOK with the IC₅₀ values in the range of 0.19-0.26 μM. Normal oral keratinocytes and normal gingival fibroblasts were less sensitive to the treatment. Flubendazole and mebendazole also reduced the migration of the PE/CA-PJ15 cell in concentrations that had no anti-migratory effects on the normal gingival fibroblasts. Levels of the focal adhesion kinase FAK, Rho-A and Rac1 GTPases and the Rho guanine nucleotide exchange factor GEF-H1 were decreased in both PE/CA-PJ15 cells and gingival fibroblasts following treatment. Both drugs also interfered with cadherin switching in the model of TGF-β-induced epithelial to mesenchymal transition (EMT) in the DOK cell line. Levels of N-cadherin were reduced in the TGF-β induced cells co-treated with flubendazol and mebendazole in very low concentration (50 nM). These results suggest direct effects of both benzimidazoles on selected processes of EMT in oral cell lines such as cadherin switching as well as cellular migration.

Sodium Phenylbutyrate Inhibits Tumor Growth and the Epithelial-Mesenchymal Transition of Oral Squamous Cell Carcinoma In Vitro and In Vivo

Sodium phenylbutyrate (SPB) as a salt of 4-phenylbutyric acid (4-PBA) has been reported to be an ammonia scavenger, histone deacetylase inhibitor, and an endoplasmic reticulum stress inhibitor in various diseases, including neurological diseases, inflammatory disorders, and carcinogenesis. Although phenylbutyrate showed effective antitumor properties in many cancers, its role in oral squamous cell carcinoma (OSCC) remains further characterized. Thus, the OSCC cell lines CAL27, HSC3, and SCC4 were treated with a series of doses of SPB for different times. The IC₅₀ of three cell lines for SPB was determined to be 4.0, 3.7, and 3.0 mM. The CCK-8 assay indicated that the treatment of SPB induced continuous inhibition of cell vitality of three cell lines. Apoptosis was assessed by Hoechst assay that showed that SPB could significantly promote cell apoptosis. Moreover, the apoptosis-related pathway was analyzed, and the results showed that the expression of antiapoptosis factor BCL-2 was downregulated by SPB but the cleavage of caspase-3 was increased. Meanwhile, it was found that SPB also impaired the migration and invasion of OSCC cells in vitro. Mechanistically, the transforming growth factor-β (TGFB) related epithelial-mesenchymal transition (EMT) was inhibited by SPB with decreased mesenchymal marker N-cadherin and increased epithelial marker E-cadherin. Furthermore, the antitumor effect of SPB in vivo was also demonstrated. The administration of SPB induced remarkably tumor regression with decreased tumor volume, and the TGFB level and EMT phenotype in vivo were also inhibited. These data demonstrated that the treatment of SPB could function as antitumor therapeutics for OSCC.