SOX9 promotes stemness in the CAL27 cell line of tongue squamous cell carcinoma.

Tongue squamous cell carcinoma (TSCC) is a prevalent form of oral malignancy, with increasing incidence. Unfortunately, the 5-year survival rate for patients has not exceeded 50%. Studies have shown that sex-determining region Y box 9 (SOX9) correlates with malignancy and tumor stemness in a variety of tumors. To investigate the role of SOX9 in TSCC stemness, we analyzed its influence on various aspects of tumor biology, including cell proliferation, migration, invasion, sphere and clone formation, and drug resistance in TSCC. Our data suggest a close association between SOX9 expression and both the stemness phenotype and drug resistance in TSCC. Immunohistochemical experiments revealed a progressive increase of SOX9 expression in normal oral mucosa, paracancerous tissues, and tongue squamous carcinoma tissues. Furthermore, the expression of SOX9 was closely linked to the TNM stage, but not to lymph node metastasis or tumor diameter. SOX9 is a crucial gene in TSCC responsible for promoting the stemness function of cancer stem cells. Developing drugs that target SOX9 is extremely important in clinical settings.

High-Performance Photodynamic Therapy of Tongue Squamous Cell Carcinoma with Multifunctional Nano-Verteporfin.

Background: The photodynamic therapy (PDT) showed promising potential in treating tongue squamous cell carcinoma (TSCC). The Food and Drug Administration approved Verteporfin (Ver) is a powerful alternative in this field for its penetrating power and high production of reactive oxygen species (ROS). However, its applications in the treatment of TSCC are still rare. Methods: Ver was loaded onto Poly (lactic-co-glycolic acid) (PLGA) nanoparticles, followed by the modification with RGD peptide as the ligand. The nanostructured was named as RPV. In vitro assessments were conducted to evaluate the cytotoxicity of RPV through the Live/Dead assay analysis and Cell Counting Kit-8 (CCK-8) assay. Using the reactive oxygen species assay kit, the potential for inducing targeted tumor cell death upon laser irradiation by promoting ROS production was investigated. In vivo experiments involved with the biological distribution of RPV, the administration with RPV followed by laser irradiation, and the measurement of the tumor volumes. Immunohistochemical analysis was used to detect the Ki-67 expression, and apoptosis induced by RPV-treated group. Systemic toxicity was evaluated through hematoxylin-eosin staining and blood routine analysis. Real-time monitoring was employed to track RPV accumulation at tumor sites. Results: The in vitro assessments demonstrated the low cytotoxicity of RPV and indicated its potential for targeted killing TSCC cells under laser irradiation. In vivo experiments revealed significant tumor growth inhibition with RPV treatment and laser irradiation. Immunohistochemical analysis showed a notable decrease in Ki-67 expression, suggesting the effective suppression of cell proliferation, and TUNEL assay indicated the increased apoptosis in the RPV-treated group. Pathological examination and blood routine analysis revealed no significant systemic toxicity. Real-time monitoring exhibited selective accumulation of RPV at tumor sites. Conclusion: The findings collectively suggest that RPV holds promise as a safe and effective therapeutic strategy for TSCC, offering a combination of targeted drug delivery with photodynamic therapy.

Novel Prognostic Model Construction of Tongue Squamous Cell Carcinoma Based on Apigenin-Associated Genes.

BACKGROUND: Clinical indexes are often selected as relevant factors for constructing prognostic models of tongue squamous cell carcinoma (TSCC) patients, while factors related to therapeutic targets are less frequently included. As Apigenin (API) shows anti-tumor properties in many tumors, in this study, we construct a novel prognostic model for TSCC patients based on Apigenin-associated genes through transcriptomic analysis. METHODS: The effect of Apigenin (API) on the cell characteristics of TSCC cells was measured by several phenotype experiments. RNA-seq was executed to ensure differentially expressed genes (DEGs) in squamous cell carcinoma-9 (SCC-9) cells after API treatment. Furthermore, reverse transcription quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry were performed to verify the expression of API-related genes. Then, combined with the gene expression data and relevant individual information of TSCC samples acquired from The Cancer Genome Atlas (TCGA), an API-related model was built through Lasso regression and multivariate Cox regression. A receiver operating characteristic (ROC) curve and a nomogram and calibration curve were created to forecast patient outcomes to improve the clinical suitability of the API-related signature. The relationships between the two risk groups and function enrichment, immune infiltration characteristics, and drug susceptibility were analyzed. RESULTS: We demonstrated that API could inhibit the malignant behavior of TSCC cells. Among API-related genes, TSCC cells treated with API, compared to the control group, have higher levels of transmembrane protein 213 (TMEM213) and G protein-coupled receptor 158 (GPR158), and lower levels of caspase 14 (CASP14) and integrin subunit alpha 5 (ITGA5). An 7 API-associated gene model was built through Lasso regression and multivariate Cox regression that could direct TSCC prognostic status and tumor immune cell infiltration. In addition, we acquired 6 potential therapeutic agents for TSCC based on the prognostic model. CONCLUSIONS: Our research suggested the inhibition effect of API on TSCC cells and provided a novel prognostic model combined with therapeutic factors that can guide the prognosis of TSCC and clinical decision-making in TSCC.

Negative prognostic behaviour of PD-L1 expression in tongue and larynx squamous cell carcinoma and its significant predictive power in combination with PD-1 expression on TILs.

BACKGROUND: Biomarkers that can predict outcome will improve the efficacy of treatment for HNSCC patients. In this regard, we retrospectively evaluated the prognostic effect of PD1, PD-L1, and CD45RO in tongue and larynx squamous cell carcinomas. METHODS: FFPE tissue blocks of 63 larynx and 40 tongue squamous cell carcinoma samples were selected, cut into 3 µm sections, and immunohistochemically stained for PD1, PD-L1, and CD45RO. The slides were evaluated by an expert pathologist, and results were analysed using Chi-square, univariate, and multivariable Cox regression methods. RESULTS: TC-PD-L1 expression (P = 0.001) and its expression intensity (P = 0.002) were significantly correlated with a higher percentage of PD-1 + tumor infiltrating lymphocytes. In univariate survival analysis, TC-PD-L1 and its expression intensity had a significant impact on both DFS (HR: 0.203; P = 0.003 and HR: 0.320; P = 0.005) and OS (HR: 0.147; P = 0.002 and HR: 0.322; P = 0.005). Based on the multivariate analysis, PD1 (DFS: HR: 3.202; P = 0.011, OS: HR: 2.671; P = 0.027) and TC-PD-L1 (DFS: HR: 0.174; P = 0.006, OS: HR: 0.189; P = 0.009) were found to be independent prognostic markers. In the second part, scoring systems were defined based on the expression status of PD1 and PD-L1. Patients with higher scores were expected to have longer DFS and OS. In multivariate analysis, the PD1/TC-PD-L1 (DFS: P = 0.001, OS: P = 0.003) scoring systems showed superior prognostic effects. Interestingly, at the highest levels of this score, none of the patients experienced recurrence or cancer-caused death. CONCLUSION: Collectively, this study suggests negative prognostic behaviour for TC-PD-L1 protein and introduces the PD-1/TC-PD-L1 scoring system as a strong prognostic marker in OS and DFS prediction of tongue and larynx HNSCC patients.

Immunoexpression of HSP27 does not seem to influence the prognosis of oral tongue squamous cell carcinoma.

New methods of early detection and risk assessment have been studied aiming to predict the prognosis of patients and directing a specialized treatment of the oral tongue squamous cell carcinoma (OTSCC). In this context, several molecular biomarkers have been investigated for this purpose, and, among them, the heat shock protein 27 (HSP27) can be named. The study aimed to analyze whether heat shock protein 27 (HSP27) exerts any influence on OTSCC, correlating its immunoexpression with clinicopathological parameters, and patient survival. The sample comprised 55 OTSCC cases and 20 normal oral mucosa specimens. The malignancy grading systems proposed by the WHO in 2005, Brandwein-Gensler et al., and Almangush et al. were applied in a histomorphological study. HSP27 expressions were evaluated through the Immunoreactivity Score System (IRS). Significant values were considered at p <0.05 for all statistical tests. Higher IRS results were observed for normal oral mucosa specimens when compared to OTSCC cases (p <0.001). No significant associations between HSP27 immunostaining, the analyzed clinicopathological parameters and patient survival were observed. The results of the present study indicate lower HSP27 expression in OTSCC cases compared to normal oral mucosa specimens. Thus, HSP27 expression does not seem to influence patient prognosis.

Proteolytic cleavage of amyloid precursor protein by ADAM10 promotes proliferation and migration via activating MAPKs pathway in tongue squamous cell carcinoma in vitro.

APP, well-studied in the development of Alzheimer's disease, has been recently identified as the key gene correlated with TSCC. Here, we investigate the function of APP and its proteolytic cleavage by ADAM10 in the pathogenesis of TSCC. A total of 63 TSCC patients and 30 healthy controls were included and the results of IHC assay showed high expressions of ADAM10 and APP in TSCC tissues compared to paired para-carcinoma tissues. Interestingly, APP expression in TSCC patients was correlated with ADAM10 expression and their combined expression was related to the poor patients' survival. We found that APP was ɑ-cleaved in TSCC cells to form sAPPα, and the serum level of sAPPα but not sAPPß in TSCC patients was higher than healthy controls. Both overexpression with full-length APP and sAPPα promoted TSCC cell proliferation, migration and invasion. Downregulation of APP or ADAM10 by siRNA decreased the generation of sAPPα and inhibited the activity of ERK1/2 and p38 pathways, thereby reducing TSCC cell proliferation, migration and invasion. Treatment with ERK1/2 or p38 agonist or sAPPα overexpression reversed the effects of APP or ADAM10 knockdown. In conclusion, our data demonstrated the pathogenic roles of APP cleaved by ADAM10 to activate ERK1/2 and p38 pathways in TSCC cells. Both high expressions of ADAM10 and APP were related to poor prognosis. Targeting APP cleaved by ADAM10 might be a potential strategy in TSCC treatment.

PAR2-dependent phosphorylation of TRPV4 at the trigeminal nerve terminals contributes to tongue cancer pain.

OBJECTIVE: This study aimed to clarify the interactions between the tongue and primary afferent fibers in tongue cancer pain. METHODS: A pharmacological analysis was conducted to evaluate mechanical hypersensitivity of the tongues of rats with squamous cell carcinoma (SCC). Changes in trigeminal ganglion (TG) neurons projecting to the tongue were analyzed using immunohistochemistry and western blotting. RESULTS: SCC inoculation of the tongue caused persistent mechanical sensitization and tumor formation. Trypsin expression was significantly upregulated in cancer lesions. Continuous trypsin inhibition or protease-activated receptor 2 (PAR2) antagonism in the tongue significantly inhibited SCC-induced mechanical sensitization. No changes were observed in PAR2 and transient receptor potential vanilloid 4 (TRPV4) levels in the TG or the number of PAR2-and TRPV4-expressing TG neurons after SCC inoculation. In contrast, the relative amount of phosphorylated TRPV4 in the TG was significantly increased after SCC inoculation and abrogated by PAR2 antagonism in the tongue. TRPV4 antagonism in the tongue significantly ameliorated the mechanical sensitization caused by SCC inoculation. CONCLUSIONS: Our findings indicate that tumor-derived trypsin sensitizes primary afferent fibers by PAR2 stimulation and subsequent TRPV4 phosphorylation, resulting in severe tongue pain.

Brucea javanica oil inhibits tongue squamous cell invasion and metastasis by regulating miR-138-EZH2 pathway.

Tongue squamous cell carcinoma (TSCC) is one of the most common malignant tumors of head and neck. Its incidence is on the rise, and the proportion of young patients is gradually increasing, which is prone to tumor recurrence and metastasis. At present, there is no effective method to completely treat TSCC. Studies have shown that brucea javanica oil (BJO) has good antitumor activity against lung cancer and gastrointestinal tumors, but its therapeutic effect on TSCC is not clear. We have previously confirmed that oleic acid, the main component of BJO, can induce apoptosis of TSCC and reduce its invasion and metastasis ability. However, the anticancer effect and mechanism of BJO in TSCC remain unclear. In order to further explore the effects of BJO on the biological characteristics of TSCC cells, we studied the effects of different concentrations of BJO on the migration, invasion ability and epithelial mesenchymal transition (EMT) progression of TSCC cells and the possible mechanisms through in vitro experiments. We found that BJO could inhibit the invasion and metastasis of TSCC and up-regulate miR-138. After BJO treatment, the expression of E-cad was significantly increased, while the expression of EZH2, Slug, p-ERK1/2 and Vimentin was significantly decreased. EZH2 is a miR-138 target gene involved in TSCC. BJO inhibits TSCC invasion and metastasis by regulating the miR-138-EZH2 pathway. In vivo experiments have also well demonstrated the targeting effect of this pathway. This study provides a new therapeutic strategy for the treatment of TSCC.

Identification of salivary metabolic biomarker signatures for oral tongue squamous cell carcinoma.

OBJECTIVE: To identify the salivary metabolites associated with squamous cell carcinoma of the tongue to develop easy and non-invasive potential biomarkers for disease diagnosis. DESIGN: Initially, the study utilized untargeted metabolomics to analyze 20 samples of tongue squamous cell carcinoma and 10 control samples. The objective was to determine the salivary metabolites that exhibited differential expression in tongue squamous cell carcinoma. Then the selected metabolites were validated using targeted metabolomics in saliva samples of 100 patients diagnosed with squamous cell carcinoma of the tongue, as well as 30 healthy control individuals. RESULTS: From the analysis of untargeted metabolomics, 10 metabolites were selected as potential biomarkers. In the subsequent targeted metabolomics study on these selected metabolites, it was observed that N-Acetyl-D-glucosamine, L-Pipecolic acid, L-Carnitine, Phosphorylcholine, and Deoxyguanosine exhibited significant differences. The receiver operating characteristic curve analysis indicates a combination of three important metabolites such as N-Acetyl-D-glucosamine, L-Pipecolic acid and L-Carnitine provided the best prediction with an area under the curve of 0.901. CONCLUSIONS: The present result reveals that the N-Acetyl-D-glucosamine, L-Pipecolic acid and L-Carnitine are the signature diagnostic biomarkers for oral tongue squamous cell carcinoma. These findings can be used to develop a rapid and non-invasive method for disease monitoring and prognosis in oral tongue cancer.

FDFT1 repression by piR-39980 prevents oncogenesis by regulating proliferation and apoptosis through hypoxia in tongue squamous cell carcinoma.

AIM: Tongue squamous cell carcinoma (TSCC) is one of the most aggressive tumors whose underlying molecular mechanism remains elusive. Previous studies have identified piR-39980, a non-coding RNA, as a tumour suppressor or oncogene in different malignancies and the cholesterogenic protein, Farnesyl-Diphosphate Farnesyltransferase 1 (FDFT1) playing critical roles in cancer. The present study investigates the role of piR-39980, and its target FDFT1, in regulating the malignancy of TSCC. MAIN METHODS: We performed qRT-PCR to determine the expression of FDFT1, piR-39980 and validated FDFT1 as a target of piR-39980 by dual luciferase assay. Then, to investigate the role of FDFT1 overexpression and piR-39980's inhibitory effect on FDFT1 in TSCC oncogenesis, we carried out MTT, migration, ROS estimation, and flow cytometric cell cycle assays. In addition to the above experiments, we also carried out flow cytometric apoptosis assay, chromatin condensation, γ-H2AX accumulation, and phalloidin staining assays upon overexpression and silencing of piRNA to unveil its mechanism of actions in TSCC malignancy. KEY FINDINGS: FDFT1 promotes the oncogenesis of TSCC cells. Further, transient overexpression of piR-39980 significantly inhibited proliferation, migration, ROS generation, and colony formation and increased DNA damage and chromatin condensation causing cell death by repressing FDFT1. We conjectured that FDFT1 repression induces hypoxia, which slows DNA repair and accumulates damaged DNA, causing death of TSCC cells. SIGNIFICANCE: Our study showed FDFT1 acts as an oncogene in TSCC, unlike other cancers, whose repression by a piRNA could prevent oncogenesis by regulating proliferation and apoptosis through hypoxia. This study reveals novel gene-regulatory mechanistic insights into TSCC oncogenesis.

Personal immune profiles: Diversity and prognostic value for oral tongue squamous cell carcinoma evaluated by comprehensive immune parameter analyses with multiplex immunofluorescence.

OBJECTIVES: Understanding the tumor immune microenvironment is becoming increasingly necessary for risk prediction and treatment selection. In particular, oral cancer has various immunosuppressive characteristics in the tumor microenvironment. Therefore, we comprehensively assessed the immune profiles of oral tongue squamous cell carcinoma (OTSCC). MATERIALS AND METHODS: Multiplex immunofluorescence and tissue imaging analyses were performed to evaluate immune profiles at the invasive tumor front of 60 OTSCC surgical specimens. We analyzed 58 immune parameters including the density and proportion (%) of total leukocytes (Leu) and T cells, six subsets of T and myeloid cells, and the expression of programmed cell death-1 (PD-1) and PD-1 ligand 1 (PD-L1). RESULTS: The density, proportion, and location of CD45+ Leu, three T cell subsets (CD8+, Foxp3-CD4+ conventional, and Foxp3+CD4+ regulatory T cells), CD163-CD68+ M1 and CD163+CD68+ M2 macrophages, and neutrophils were highly variable at the individual level. The density and proportion of M2 macrophages were significantly lower in the T1 stage group. Risk prediction analyses for recurrence and/or metastasis (R/M) showed that R/M (+) T1 cases had significantly higher M2 density and percentages. CONCLUSIONS: The immune profiles of OTSCC patients are diverse and cannot be predicted from clinicopathological information alone. The M2 macrophage abundance is a potential candidate biomarker for R/M in the early stage of OTSCC. Personal immune profiling may provide beneficial information for risk prediction and treatment selection.

Radiation modulates expression and related activities of c-Met protein in oral tongue squamous cell carcinoma cell lines.

OBJECTIVES: c-Met, a receptor tyrosine kinase, is involved in the growth, invasion and metastasis of a variety of cancers. In a set of cell lines from several solid tumors, a five-fold increase in c-Met expression after irradiation has been reported. This study aimed to assess if c-Met is likewise abundantly expressed in oral tongue squamous cell carcinoma (OTSCC) upon exposure to irradiation, followed by a Met-induced biological response. MATERIALS AND METHODS: Six OTSCC cell lines were exposed to gamma radiation doses of 2, 4, and 6 Gray. The changes in c-Met protein levels were assessed by western blot and flow cytometry. c-Met gene expression, cell migration, proliferation and cell cycle assays were performed as phenotypic readouts. RESULTS: Irradiation resulted in upregulation of c.Met in all cell lines with different time kinetics. On average the cells displayed minimal c-Met expression on their surface ranging from 5 to 30% of total protein. Abrupt downregulation of c-Met surface expression occurred one hour after radiation but recovered 48 h post-radiation. Intracellularly, the highest level of expression was found on day 5 after radiation exposure. Irradiation induced aggressive invasive potential of the cells as determined in cell migration assays, particularly in cell lines with the highest c-Met expression. CONCLUSIONS: These results provide novel insights into both intracellular and extracellular dynamics of c-Met expression profiles upon irradiation of OTSCC cells in vitro. It might also suggest that radiation enhances cell migration, indicative of invasiveness, through c-Met up-regulation, at least for certain types of OTSCC cells.

miRNome-transcriptome analysis unveils the key regulatory pathways involved in the tumorigenesis of tongue squamous cell carcinoma.

Tongue squamous cell carcinoma (TSCC) is considered the most common malignant tumor among the oral squamous cell carcinomas with a poor prognosis. Understanding the underlying molecular mechanisms that underpin TSCC and its treatments is the focus of the research. Deregulated expression of microRNAs (miRNAs) has recently been implicated in various biological processes linked to cancer. Therefore, in this study, we attempted to investigate miRNAs and their targets expressed in TSCC, which could be involved in its oncogenesis. We performed next-generation sequencing of small RNAs and transcriptomes in H357 TSCC cell line and human oral keratinocytes as a control to find miRNAs and mRNAs that are differentially expressed (DE), which were then supplemented with additional expression datasets from databases, yielding 269 DE miRNAs and 2094 DE genes. The target prediction followed by pathway and disease function analysis revealed that the DE targets were significantly associated with the key processes and pathways, such as apoptosis, epithelial-mesenchymal transition, endocytosis and vascular endothelial growth factor signaling pathways. Furthermore, the top 12 DE targets were chosen based on their involvement in more than one cancer-related pathway, of which 6 genes are targeted by miR-128-3p. Real-time quantitative PCR validation of this miRNA and its targets in H357 and SCC9 TSCC cells confirmed their possible targeting from their reciprocal expression, with MAP2K7 being a critical target that might be involved in oncogenesis and progression of TSCC by acting as a tumor suppressor. Further research is underway to understand how miR-128-3p regulates oncogenesis in TSCC via MAP2K7 and associated pathways.

Qilan preparation inhibits proliferation and induces apoptosis by down-regulating microRNA-21 in human Tca8113 tongue squamous cell carcinoma cells.

OBJECTIVE: The aim of this study was to examine the antitumor effects of Qilan preparation on oral squamous cell carcinoma (OSCC) and to investigate its underlying mechanisms of action. METHODS: Cell proliferation, cell cycle distribution and apoptosis were examined using cell counting kit-8 (CCK8) and flow cytometry (FCM). The expression of PTEN and PDCD4 were determined by western blot. Changes in miR-21 levels were quantified using TaqMan stem-loop real-time PCR. After miR-21 was transiently transfected into Tca8113 cells using Lipofectamine®3000, cell proliferation, apoptosis and miR-21 and PDCD4 expression levels were measured. RESULTS: Qilan preparation inhibited Tca8113 cell growth in a dose- and time-dependent manner by inducing apoptosis and cell cycle arrest in S-phase, decreasing miR-21 levels and increasing PTEN and PDCD4 expression. MiR-21 overexpression reversed the Qilan preparation-induced suppression of cell proliferation and induction of apoptosis while also blocking the increase in PDCD4. CONCLUSIONS: Our study revealed, for the first time, the ability of Qilan preparation to suppress TSCC cell growth and elucidated that Qilan preparation elicits its anti-cancer actions either the miR-21/PDCD4 or PTEN pathway.

Tongue squamous cell carcinoma resists hyperthermia treatment by promoting Id-1 expression mediated EMT.

Epithelial-mesenchymal transition (EMT) is a key initial step in the recurrence and metastasis of tongue squamous cell carcinoma (TSCC). Hyperthermia (HT) may reduce the rate of postoperative recurrence and distant metastasis by reversing the process of EMT of tumor cells, but the molecular mechanism is unclear. This study aims to investigate the role of inhibitor of differentiation/DNA binding-1 (Id-1) in HT mediated reversal of EMT of TSCC cells, and to provide a new approach for the treatment of TSCC using therapeutic gene targeting. After the combination of RNA interference with Id-1 and HT, the morphology of TSCC cells changed from spindle-like to pebble-like, and the arrangement of cells changed from loose and disorderly to compact and orderly. The silencing of Id-1 gene enhances the efficacy of HT by affecting the expression of EMT markers in TSCC cells. This study suggests that the Id-1 gene in TSCC cells can regulate transforming growth factor-beta 1, thereby affecting the expression of EMT markers, to achieve the effect of reducing HT.

TRPC1 correlates with poor tumor features, radiotherapy efficacy and survival in tongue squamous cell carcinoma.

Aim: The present study aimed to explore the clinical association of TRPC1 with tongue squamous cell carcinoma (TSCC) tumor features and prognosis. Methods: A total of 246 TSCC patients who underwent surgical resection were retrospectively analyzed, and their tissue specimens were acquired for TRPC1 protein and mRNA detection. Results: TRPC1 protein immunohistochemistry score and mRNA expression were of good value in differentiating TSCC tissue from tumor-adjacent tissue and were positively correlated with pathological grade and tumor node metastasis stage. A high TRPC1 protein score was negatively correlated with overall survival, and this correlation was dramatically obvious in patients who received adjuvant radiotherapy. Conclusion: TRPC1 correlates with poor tumor features and unfavorable survival in TSCC patients.

Yes-associated protein 1 exerts its tumor-promoting effects and increases cisplatin resistance in tongue squamous cell carcinoma cells by dysregulating Hippo signal pathway.

Tongue squamous cell carcinoma (TSCC) has been well-known for its high metastasis and poor prognosis, but the molecular mechanisms of TSCC pathogenesis and chemoresistance are still largely unknown. Thus, the present study aimed to identify the involvement of a classic Hippo/Yes-associated protein 1 (YAP1) pathway in regulating TSCC progression and cisplatin (DDP) resistance. DDP-resistant TSCC cell lines were established by gradual exposure to DDP. Through western blot analysis, the protein expression of Hippo/YAP1 axis in TSCC tissues and cell lines was detected separately. Then, YAP1 was inhibited or overexpressed in TSCC cells. Cell viability and drug resistance were evaluated by cell counting kit-8 method, colony formation assay and Trypan blue staining assay. Cell migration ability was measured by Transwell assay. The Hippo pathway was dysregulated, and YAP1 was upregulated and dephosphorylated in the TSCC tissues or DDP-resistant cell lines, compared with normal tissues or DDP-sensitive cells. YAP1 knockdown inhibited cell proliferation, colony formation ability and migration, whereas overexpression of YAP1 exacerbated these malignant characteristics. YAP1 knockdown increased DDP-sensitivity by reducing the RAD51-mediated DNA damage repair behavior under DDP intervention in the DDP-resistant TSCC cells. Conversely, YAP1 overexpression significantly increased DDP-resistance by enhancing the RAD51-mediated DNA damage repair behavior under DDP intervention in the DDP-sensitive TSCC cells. In a word, upregulation and dephosphorylation of YAP1 caused dysregulation of the tumor-inhibiting Hippo pathway, resulting in the aggressiveness and DDP resistance in TSCC.

The enhanced genomic 6 mA metabolism contributes to the proliferation and migration of TSCC cells.

In contrast to the well-established genomic 5-methylcytosine (5mC), the existence of N6-methyladenine (6 mA) in eukaryotic genomes was discovered only recently. Initial studies found that it was actively regulated in cancer cells, suggesting its involvement in the process of carcinogenesis. However, the contribution of 6 mA in tongue squamous cell carcinoma (TSCC) still remains uncharacterized. In this study, a pan-cancer type analysis was first performed, which revealed enhanced 6 mA metabolism in diverse cancer types. The study was then focused on the regulation of 6 mA metabolism, as well as its effects on TSCC cells. To these aspects, genome 6 mA level was found greatly increased in TSCC tissues and cultured cells. By knocking down 6 mA methylases N6AMT1 and METTL4, the level of genomic 6 mA was decreased in TSCC cells. This led to suppressed colony formation and cell migration. By contrast, knockdown of 6 mA demethylase ALKBH1 resulted in an increased 6 mA level, enhanced colony formation, and cell migration. Further study suggested that regulation of the NF-κB pathway might contribute to the enhanced migration of TSCC cells. Therefore, in the case of TSCC, we have shown that genomic 6 mA modification is involved in the proliferation and migration of cancer cells.

The Wnt Signaling Pathway Inhibitors Improve the Therapeutic Activity of Glycolysis Modulators against Tongue Cancer Cells.

Excessive glucose metabolism and disruptions in Wnt signaling are important molecular changes present in oral cancer cells. The aim of this study was to evaluate the effects of the combinatorial use of glycolysis and Wnt signaling inhibitors on viability, cytotoxicity, apoptosis induction, cell cycle distribution and the glycolytic activity of tongue carcinoma cells. CAL 27, SCC-25 and BICR 22 tongue cancer cell lines were used. Cells were treated with inhibitors of glycolysis (2-deoxyglucose and lonidamine) and of Wnt signaling (PRI-724 and IWP-O1). The effects of the compounds on cell viability and cytotoxicity were evaluated with MTS and CellTox Green tests, respectively. Apoptosis was evaluated by MitoPotential Dye staining and cell cycle distribution by staining with propidium iodide, followed by flow cytometric cell analysis. Glucose and lactate concentrations in a culture medium were evaluated luminometrically. Combinations of 2-deoxyglucose and lonidamine with Wnt pathway inhibitors were similarly effective in the impairment of oral cancer cells' survival. However, the inhibition of the canonical Wnt pathway by PRI-724 was more beneficial, based on the glycolytic activity of the cells. The results point to the therapeutic potential of the combination of low concentrations of glycolytic modulators with Wnt pathway inhibitors in oral cancer cells.

Cyclin-dependent kinase 5 promotes the growth of tongue squamous cell carcinoma through the microRNA 513c-5p/cell division cycle 25B pathway and is associated with a poor prognosis.

BACKGROUND: The objective of this study was to investigate the role and molecular mechanism of cyclin-dependent kinase 5 (CDK5) in regulating the growth of tongue squamous cell carcinoma (TSCC). METHODS: The authors used multiple methods to detect the levels of CDK5 expression in samples of TSCC and to explore the relation between CDK5 expression and various clinicopathologic factors. In vivo and in vitro cell experiments were performed to detect the proliferation, invasion, and migration of TSCC cells with CDK5 knockdown or overexpression. These studies verified that CDK5 regulates the occurrence and development of TSCC cells through the microRNA 513c-5p/cell division cycle 25B pathway. RESULTS: An elevated level of CDK5 expression in TSCC tissues was identified as an independent risk factor affecting TSCC growth and patient prognosis. Patients who had TSCC with low levels of CDK5 expression had a higher survival rate than those with high levels. Knockdown of CDK5 reduced the proliferation, migration, and invasion of TSCC cells both in vitro and in vivo. In addition, the authors observed that CDK5 regulated the growth of TSCC through the microRNA 513c-5p/cell division cycle C25B pathway. CONCLUSIONS: CDK5 functions as an oncogene in TSCC and might serve as a molecular marker for use in the diagnosis and treatment of TSCC. LAY SUMMARY: Tongue squamous cell carcinoma (TSCC) is 1 of the most common malignant tumors of the head and neck, and the survival rate of patients with tongue cancer has been very low. Therefore, it is important to study the molecular mechanism of TSCC progression to identify biomarkers that can be used to improve its clinical diagnosis and treatment. Cyclin-dependent kinase 5 (CDK5) is an atypical member of the cyclin-dependent kinase family and is involved in regulating the cell cycle. Changes in the cell cycle are of great significance for the occurrence and development of tumor cells; and, in recent years, increasing evidence has suggested that CDK5 exists in a disordered state in cancer cells. In this study, the authors demonstrate that CDK5 functions as an oncogene in TSCC and might serve as a molecular marker for use in the diagnosis and treatment of TSCC.