Variant sublines with different metastatic potentials selected in nude mice from human oral squamous cell carcinomas

Ladinin-1 in actin arcs of oral squamous cell carcinoma is involved in cell migration and epithelial phenotype

Histopathologically, oral squamous cell carcinoma (OSCC) consists of well-defined interfaces with adjacent non-cancerous epithelium. Previously, we found that SCC tissues expressed higher levels of specific proteins at this interface. Ladinin-1 (LAD1) is one of the specific molecules that has increased expressions in cancer fronts; however, its function in OSCC is unknown. Therefore, this study aimed to elucidate the function of LAD1 in human OSCC cells. LAD1 was localized on the actin arc at the distal periphery of cell clusters in the OSCC cell lines HSC-2, HSC-3, and HSC-4. When LAD1 was knocked down, cellular migration was repressed in wound scratch assays but was reversed in three-dimensional collagen gel invasion assays. Characteristic LAD1 localization along actin arcs forming the leading edge of migrating cells was diminished with loss of filopodia formation and ruffling in knockdown cells, in which the expression levels of cell motility-related genes-p21-activated kinase 1 (PAK1) and caveolin-1 (CAV1)-were upregulated and downregulated, respectively. LAD1 expression was also associated with the downregulation of vimentin and increased histological differentiation of OSCC. These results suggest that LAD1 is involved in actin dynamics during filopodia and lamellipodia formation, and in maintaining the epithelial phenotype of OSCC cells.

PRF Lysates Modulate Chemokine Expression in Oral Squamous Carcinoma and Healthy Epithelial Cells

Platelet-rich fibrin (PRF), originally used to support soft tissue healing, is also considered a therapeutic option for treating oral lichen planus and leukoplakia. The progression from the two premalignant lesions to the aggressive malignant oral squamous cell carcinoma involves an inflammatory process linked to chemokine expression. Thus, there is a rationale for studying how PRF modulates the expression of chemokines in oral squamous carcinoma cells. To this aim, we expose the oral squamous carcinoma cell line HSC2 to IL1β and TNFα either alone or in the presence of lysates obtained from solid PRF membranes. We report here that in HSC2 cells, PRF lysates significantly reduce the forced transcription of chemokines, e.g., CXCL1, CXCL2, CXCL8, CXCL10, and CCL5. Moreover, PRF lysates attenuate the nuclear translocation of p65 in HSC2 oral epithelial cells when exposed to IL1β and TNFα. PRF lysates further reduce chemokine expression provoked by poly:IC HMW. Even though less pronounced, PRF lysates reduce IL1β- and TNFα-induced chemokine expression in TR146 cells. In primary oral epithelial cells, however, PRF lysates increase the basal expression of CXCL1, CXCL2 and CXCL8. Thus, PRF can exert a biphasic effect on chemokine expression in oral squamous cell carcinoma cell lines and primary oral epithelial cells. These findings suggest that PRF may reduce inflammation in a malignant environment while provoking an immunological response in healthy oral epithelium.

Cathepsin X deficiency alters the processing and localisation of cathepsin L and impairs cleavage of a nuclear cathepsin L substrate

Proteases function within sophisticated networks. Altering the activity of one protease can have sweeping effects on other proteases, leading to changes in their activity, structure, specificity, localisation, stability, and expression. Using a suite of chemical tools, we investigated the impact of cathepsin X, a lysosomal cysteine protease, on the activity and expression of other cysteine proteases and their inhibitors in dendritic cells. Among all proteases examined, cathepsin X gene deletion specifically altered cathepsin L levels; pro-cathepsin L and its single chain accumulated while the two-chain form was unchanged. This effect was recapitulated by chemical inhibition of cathepsin X, suggesting a dependence on its catalytic activity. We demonstrated that accumulation of pro- and single chain cathepsin L was not due to a lack of direct cleavage by cathepsin X or altered glycosylation, secretion, or mRNA expression but may result from changes in lysosomal oxidative stress or pH. In the absence of active cathepsin X, nuclear cathepsin L and cleavage of the known nuclear cathepsin L substrate, Lamin B1, were diminished. Thus, cathepsin X activity selectively regulates cathepsin L, which has the potential to impact the degree of cathepsin L proteolysis, the nature of substrates that it cleaves, and the location of cleavage.

EP4-induced mitochondrial localization and cell migration mediated by CALML6 in human oral squamous cell carcinoma

Lymph node metastasis, primarily caused by the migration of oral squamous cell carcinoma (OSCC) cells, stands as a crucial prognostic marker. We have previously demonstrated that EP4, a subtype of the prostaglandin E2 (PGE2) receptor, orchestrates OSCC cell migration via Ca2+ signaling. The exact mechanisms by which EP4 influences cell migration through Ca2+ signaling, however, is unclear. Our study aims to clarify how EP4 controls OSCC cell migration through this pathway. We find that activating EP4 with an agonist (ONO-AE1-473) increased intracellular Ca2+ levels and the migration of human oral cancer cells (HSC-3), but not human gingival fibroblasts (HGnF). Further RNA sequencing linked EP4 to calmodulin-like protein 6 (CALML6), whose role remains undefined in OSCC. Through protein-protein interaction network analysis, a strong connection is identified between CALML6 and calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2), with EP4 activation also boosting mitochondrial function. Overexpressing EP4 in HSC-3 cells increases experimental lung metastasis in mice, whereas inhibiting CaMKK2 with STO-609 markedly lowers these metastases. This positions CaMKK2 as a potential new target for treating OSCC metastasis. Our findings highlight CALML6 as a pivotal regulator in EP4-driven mitochondrial respiration, affecting cell migration and metastasis via the CaMKK2 pathway.

Resveratrol is an inhibitory polyphenol of epithelial-mesenchymal transition induced by Fusobacterium nucleatum

OBJECTIVE

Resveratrol is a natural phytoalexin that has anti-inflammatory properties, reverses doxorubicin resistance, and inhibits epithelial-mesenchymal transition (EMT) in many types of cancer cells. Fusobacterium nucleatum is reportedly enriched in oral squamous cell carcinoma (OSCC) tissues compared to adjacent normal tissues, sparking interest in the relationship between F. nucleatum and OSCC. Recently, F. nucleatum was shown to be associated with EMT in OSCC. In the present study, we aimed to investigate the effects of the natural plant compound resveratrol on F. nucleatum-induced EMT in OSCC.

DESIGN

F. nucleatum was co-cultured with OSCC cells, with a multiplicity of infection (MOI) of 300:1. Resveratrol was used at a concentration of 10 μM. Cell Counting Kit-8 and wound healing assays were performed to examine the viability and migratory ability of OSCC cells. Subsequently, real-time RT-PCR was performed to investigate the gene expression of EMT-related markers. Western blotting and immunofluorescence analyses were used to further analyze the expression of the epithelial marker E-cadherin and the EMT transcription factor SNAI1.

RESULTS

Co-cultivation with F. nucleatum did not significantly enhance cell viability. The co-cultured cells displayed similarities to the positive control of EMT, exhibiting enhanced migration and expression changes in EMT-related markers. SNAI1 was significantly upregulated, whereas E-cadherin, was significantly downregulated. Notably, resveratrol inhibited F. nucleatum-induced cell migration, decreasing the expression of SNAI1.

CONCLUSIONS

Resveratrol inhibited F. nucleatum-induced EMT by downregulating SNAI1, which may provide a target for OSCC treatment.

Disruption of CADM1-dependent cell-cell adhesion in human oral squamous cell carcinoma cells results in tumor progression, possibly through an increase of MMP-2 and MMP-9 expression

OBJECTIVES

This study aimed to clarify the molecular mechanism underlying the higher invasion and metastasis abilities of LMF4 cells than those of HSC-3 cells by comparing the expression levels of the tumor suppressor factor, cell adhesion molecule 1 (CADM1).

METHODS

We explored 1) whether CADM1 expression level was downregulated in LMF4 cells compared with HSC-3 cells, 2) whether CADM1 expression knockdown increased the expression levels of matrix metalloproteinases (MMPs), 3) the exact cellular signaling pathways responsible for increased MMP expression after knockdown of CADM1 expression, and 4) whether disruption of CADM1-dependent HSC-3 cell adhesion increased the migratory and invasive activities of HSC-3 cells.

RESULTS

CADM1 expression was lower in the LMF4 than in the HSC-3 cells. The knockdown of CADM1 increased the expression of MMP-2 and MMP-9 in HSC-3 cells. In addition, the upregulation of MMP-2 expression after CADM1 knockdown was abrogated by the mitogen-activated protein (MAP)/extracellular signal-regulated kinase kinase (MEK) inhibitor U0126 and the phosphoinositide 3-kinase (PI3K) inhibitor LY294002. The upregulation of MMP-9 expression after the knockdown of CADM1 was abrogated by the c-Jun N-terminal kinase (JNK) inhibitor SP600125 and the p38 MAP kinase (MAPK) inhibitor SB203580 and LY294002. Anti-CADM1 neutralizing antibody evoked migratory and invasive abilities of HSC-3 cells.

CONCLUSION

The disruption of CADM1-dependent cell-cell adhesion in human oral squamous cell carcinoma cells resulted in tumor progression, possibly through an increase in MMP-2 expression in a MEK/PI3K-dependent manner and an increase in MMP-9 expression in a JNK/p38 MAPK/PI3K-dependent manner.

The clinical implication and translational research of OSCC differentiation

BACKGROUND

The clinical value and molecular characteristics of tumor differentiation in oral squamous cell carcinoma (OSCC) remain unclear. There is a lack of a related molecular classification prediction system based on pathological images for precision medicine.

METHODS

Integration of epidemiology, genomics, experiments, and deep learning to clarify the clinical value and molecular characteristics, and develop a novel OSCC molecular classification prediction system.

RESULTS

Large-scale epidemiology data (n = 118,817) demonstrated OSCC differentiation was a significant prognosis indicator (p < 0.001), and well-differentiated OSCC was more chemo-resistant than poorly differentiated OSCC. These results were confirmed in the TCGA database and in vitro. Furthermore, we found chemo-resistant related pathways and cell cycle-related pathways were up-regulated in well- and poorly differentiated OSCC, respectively. Based on the characteristics of OSCC differentiation, a molecular grade of OSCC was obtained and combined with pathological images to establish a novel prediction system through deep learning, named ShuffleNetV2-based Molecular Grade of OSCC (SMGO). Importantly, our independent multi-center cohort of OSCC (n = 340) confirmed the high accuracy of SMGO.

CONCLUSIONS

OSCC differentiation was a significant indicator of prognosis and chemotherapy selection. Importantly, SMGO could be an indispensable reference for OSCC differentiation and assist the decision-making of chemotherapy.

Metabolic Patterns of High-Invasive and Low-Invasive Oral Squamous Cell Carcinoma Cells Using Quantitative Metabolomics and 13C-Glucose Tracing

Most current metabolomics studies of oral squamous cell carcinoma (OSCC) are mainly focused on identifying potential biomarkers for early screening and diagnosis, while few studies have investigated the metabolic profiles promoting metastasis. In this study, we aimed to explore the altered metabolic pathways associated with metastasis of OSCC. Here, we identified four OSCC cell models (CAL27, HN6, HSC-3, SAS) that possess different invasive heterogeneity via the transwell invasion assay and divided them into high-invasive (HN6, SAS) and low-invasive (CAL27, HSC-3) cells. Quantitative analysis and stable isotope tracing using [U-13C6] glucose were performed to detect the altered metabolites in high-invasive OSCC cells, low-invasive OSCC cells and normal human oral keratinocytes (HOK). The metabolic changes in the high-invasive and low-invasive cells included elevated glycolysis, increased fatty acid metabolism and an impaired TCA cycle compared with HOK. Moreover, pathway analysis demonstrated significant differences in fatty acid biosynthesis; arachidonic acid (AA) metabolism; and glycine, serine and threonine metabolism between the high-invasive and low-invasive cells. Furthermore, the high-invasive cells displayed a significant increase in the percentages of 13C-glycine, 13C-palmitate, 13C-stearic acid, 13C-oleic acid, 13C-AA and estimated FADS1/2 activities compared with the low-invasive cells. Overall, this exploratory study suggested that the metabolic differences related to the metastatic phenotypes of OSCC cells were concentrated in glycine metabolism, de novo fatty acid synthesis and polyunsaturated fatty acid (PUFA) metabolism, providing a comprehensive understanding of the metabolic alterations and a basis for studying related molecular mechanisms in metastatic OSCC cells.

Dual roles of cellular communication network factor 6 (CCN6) in the invasion and metastasis of oral cancer cells to bone via binding to BMP2 and RANKL

The acquisition of motility via epithelial-mesenchymal transition (EMT) and osteoclast induction are essential for the invasion and metastasis of oral squamous cell carcinoma (OSCC) to bone. However, the molecule suppressing both EMT and osteoclastogenesis is still unknown. In this study, we found that cellular communication network factor 6 (CCN6) was less produced in a human OSCC cell line, HSC-3 with mesenchymal phenotype, than in HSC-2 cells without it. Notably, CCN6 interacted with bone morphogenetic protein 2 (BMP2) and suppressed the cell migration of HSC-3 cells stimulated by BMP2. Moreover, knockdown of CCN6 in HSC-2 cells led to the promotion of EMT and enhanced the effect of transforming growth factor-β (TGF-β) on the promotion of EMT. Furthermore, CCN6 combined with BMP2 suppressed EMT. These results suggest that CCN6 strongly suppresses EMT in cooperation with BMP2 and TGF-β. Interestingly, CCN6 combined with BMP2 increased the gene expression of receptor activator of nuclear factor-κB ligand (RANKL) in HSC-2 and HSC-3 cells. Additionally, CCN6 interacted with RANKL, and CCN6 combined with RANKL suppressed RANKL-induced osteoclast formation. In metastatic lesions, increasing BMP2 due to the bone destruction led to interference with binding of CCN6 to RANKL, which results in the promotion of bone metastasis of OSCC cells due to continuous osteoclastogenesis. These findings suggest that CCN6 plays dual roles in the suppression of EMT and in the promotion of bone destruction of OSCC in primary and metastatic lesions, respectively, through cooperation with BMP2 and interference with RANKL.

PRF Lysates Enhance the Proliferation and Migration of Oral Squamous Carcinoma Cell Lines

Platelet-rich fibrin (PRF) is an autologous fibrin-rich matrix where activated platelets and leucocytes accumulate. PRF has a wide spectrum of clinical indications with the overall aim of supporting tissue regeneration which in dentistry includes the healing of healthy oral mucosa with epithelial cells. In oral squamous cell carcinoma lesions, however, epithelial cells undergo malignant transformation, indicated by their unrestricted proliferation and migration potential, which should not be further enhanced by a wound-healing formula. Yet, little is known about how oral squamous cell carcinomas respond to PRF lysates. The aim of the present study was, therefore, to test the capacity of PRF lysates to change the transcriptome of HSC2 oral squamous carcinoma cells and perform bioassays to support the findings. Based on the RNAseq analysis, PRF lysates caused an increase in the genes functionally linked to cell replication and migration. In support of this screening approach, PRF lysates enhanced the proliferation of HSC2 oral squamous carcinoma cells, as indicated by 3[H]-thymidine incorporation, cell counting, and the expression of proliferation-related genes. Moreover, PRF lysates sped up cell migration in a scratch assay requiring actin polymerization. Taken together, our data showing that PRF lysates are mitogenic and stimulate motility of oral squamous carcinoma cell lines could be an indication that treatment with PRF in cases of oral carcinoma should be carefully considered.

β-catenin/CBP activation of mTORC1 signaling promotes partial epithelial-mesenchymal states in head and neck cancer

Head and neck cancers, which include oral squamous cell carcinoma (OSCC) as a major subsite, exhibit cellular plasticity that includes features of an epithelial-mesenchymal transition (EMT), referred to as partial-EMT (p-EMT). To identify molecular mechanisms contributing to OSCC plasticity, we performed a multiphase analysis of single cell RNA sequencing (scRNAseq) data from human OSCC. This included a multiresolution characterization of cancer cell subgroups to identify pathways and cell states that are heterogeneously represented, followed by casual inference analysis to elucidate activating and inhibitory relationships between these pathways and cell states. This approach revealed signaling networks associated with hierarchical cell state transitions, which notably included an association between β-catenin-driven CREB-binding protein (CBP) activity and mTORC1 signaling. This network was associated with subpopulations of cancer cells that were enriched for markers of the p-EMT state and poor patient survival. Functional analyses revealed that β-catenin/CBP induced mTORC1 activity in part through the transcriptional regulation of a raptor-interacting protein, chaperonin containing TCP1 subunit 5 (CCT5). Inhibition of β-catenin-CBP activity through the use of the orally active small molecule, E7386, reduced the expression of CCT5 and mTORC1 activity in vitro, and inhibited p-EMT-associated markers and tumor development in a murine model of OSCC. Our study highlights the use of multiresolution network analyses of scRNAseq data to identify targetable signals for therapeutic benefit, thus defining an underappreciated association between β-catenin/CBP and mTORC1 signaling in head and neck cancer plasticity.

Role of Stromal Fibroblast-Induced WNT7A Associated with Cancer Cell Migration Through the AKT/CLDN1 Signaling Axis in Oral Squamous Cell Carcinoma

Wnt signaling plays a crucial role in the progression of various cancers, including oral squamous cell carcinoma (OSCC). However, the tumor microenvironment (TME) regulating Wnt signaling has not yet been fully elucidated. In this study, we investigated whether cancer-associated fibroblasts (CAFs), the primary components of the TME, activate Wnt signaling and promote tumor progression in OSCC. We conducted a Transwell coculture assay using human OSCC cell lines and normal human dermal fibroblasts (NHDFs). NHDFs stimulated WNT7A expression in several OSCC cell lines, especially HO-1-N-1 and HSC-5. An immunohistochemical study using 122 human OSCC samples indicated that high WNT7A expression in tumor cells was significantly associated with invasion depth and poor prognosis. Moreover, WNT7A expression in OSCC cells was positively correlated with α-smooth muscle actin expression in CAFs. WNT7A knockdown in OSCC cells demonstrated that OSCC cells cocultured with NHDFs significantly promoted tumor cell migration and invasion, which was dependent on WNT7A expression in OSCC cells. We also isolated HSC-5 cells from the coculture and conducted microarray analysis to investigate the factors that promote tumor progression induced by WNT7A. Among the various differentially expressed genes, we identified a downregulated gene encoding CLDN1 and confirmed that WNT7A negatively regulated CLDN1 expression in OSCC cells and CLDN1 knockdown in OSCC cells promoted their migration. Phosphokinase array analysis showed that WNT7A activates protein kinase B (AKT) phosphorylation. Activating AKT signaling using the SC79 agonist induced CLDN1 downregulation in OSCC cells. In the coculture assay, the AKT inhibitor MK2206 significantly recovered CLDN1 expression downregulated by WNT7A, resulting in OSCC cell migration suppression. These results suggest that CAFs stimulate OSCC cells to produce WNT7A, following CLDN1 expression downregulation by activating AKT signaling, promoting cancer cell migration. These findings highlight the importance of molecular therapies targeting the TME in OSCC.

Effects of Chrysin on Oral Squamous Cell Carcinoma In Vitro

OBJECTIVE

 Chrysin is a hydroxylated flavonoid derived from "propolis or bee glue," a natural product. Previous research on chrysin's biological functions, including anticancer activity, had been reported. However, chrysin's effect on oral squamous cell carcinoma (OSCC) is still scarce. This article aimed to test the cytotoxicity, antiproliferative, antimigration, anti-invasion, and apoptotic effects of purified chrysin in two OSCC cell lines, HSC4 and SCC25.

MATERIALS AND METHODS

 The malignant phenotype was assessed using cell proliferation, wound healing, and transwell assays. Cell apoptosis was determined using flow cytometry. The positive control was OSCC cells treated with cisplatin, and the negative control was OSCC cells incubated with 0.1% dimethyl sulfoxide.

RESULTS

 Chrysin at concentrations of 100 and 200 µM could inhibit OSCC cell proliferation, migration, and invasion, as well as enhance cell apoptosis, particularly in the early stages of apoptosis.

CONCLUSION

 In OSCC cell lines, chrysin has been demonstrated to be an effective antioncogenic agent. Additional research is required to confirm the results. Chrysin should be suggested as a possible alternative therapeutic application for OSCC.

Detection of herpes simplex virus in oral tongue squamous cell carcinoma

Introduction: Oral tongue squamous cell carcinoma (OTSCC) is the most common cancer of the oral cavity. Contradictory results have been observed on the involvement of herpes simplex virus 1 (HSV-1) in oral squamous cell carcinomas. Here, we aimed to study the predominance of HSV-1 or HSV-2 in oral HSV infections and to investigate the presence of HSV-1 in OTSCC and its effect on carcinoma cell viability and invasion. Methods: The distribution of HSV types one and two in diagnostic samples taken from suspected oral HSV infections was determined from the Helsinki University Hospital Laboratory database. We then analysed 67 OTSCC samples for HSV-1 infection using immunohistochemical staining. We further tested the effects of HSV-1 using six concentrations (0.00001-1.0 multiplicity of infection [MOI]) on viability and two concentrations (0.001 and 0.1 MOI) on invasion of highly invasive metastatic HSC-3 and less invasive primary SCC-25 OTSCC cell lines using MTT and Myogel-coated Transwell invasion assays. Results: Altogether 321 oropharyngeal samples were diagnosed positive for HSV during the study period. HSV-1 was the predominant (97.8%) HSV type compared with HSV-2 (detected in 2.2% of samples). HSV-1 was also detected in 24% of the OTSCC samples and had no association with patient survival or recurrence. OTSCC cells were viable even after 6 days with low viral load (0.00001, 0.0001, 0.001 MOI) of HSV-1. In both cell lines, 0.001 MOI did not affect cell invasion. However, 0.1 MOI significantly reduced cell invasion in HSC-3 cells. Discussion: HSV-1 infection is predominant compared with HSV-2 in the oral cavity. HSV-1 is detected in OTSCC samples without clinical significance, and OTSCC cell survival or invasion was not affected at low doses of HSV-1.

Inhibition of human oral squamous cell carcinoma proliferation and migration by prodrug-activating suicide gene therapies

Head and neck squamous cell carcinoma (HNSCC), which originates from mucosal epithelium in the oral cavity, pharynx and larynx, is the sixth most common malignancy in the world. The prognosis of HNSCC is not satisfactory due to metastasis, resulting in 5-year survival rates ranging from 65.9 to 67.2%. Previously, we developed a method to evaluate the effect prodrug-activating suicide gene (PA-SG) therapy on the proliferation of HNSCC. The present study investigated PA-SG therapy on metastatic HNSCC by wound-healing assay and our previously established method. HSC-3 cells with stable expression of suicide genes thymidine kinase (TK) or cytosine deaminase (CD) were treated with prodrugs ganciclovir (GCV) or 5-fluorocytosine (5-FC), respectively. Both GCV and 5-FC inhibited HSC-3 proliferation while the bystander effect of CD/5-FC was greater compared with that of TK/GCV. GCV showed a greater anti-migration effect compared with that of 5-FC. To the best of our knowledge, the present study is the first to evaluate the anti-migratory and anti-proliferative effects of PA-SG therapies on metastatic HNSCC. This may also serve as a general method to quantify other types of PA-SC therapy. The present results demonstrated that PA-SG therapy is a promising treatment for anti-metastatic HNSCC therapy development.

The role of H3K9me3 in oral squamous cell carcinoma

Carcinogenesis is often associated with alteration of epigenetic marks, including histone modifications. The global level and local distribution of specific histone modifications have been revealed to be prognostic factors in many cancers. However, the functional roles of histone modifications in oral squamous cell carcinoma (OSCC) remain unclear. This study investigates the levels of various histone modifications in 6 types of OSCC cell lines. We found that the level of H3K9me3 was significantly high in metastatic cell lines. In addition, the loss of H3K9me3 by SUV39H1 and SUV39H2 knockdown suppressed cell proliferation and cell migration. Our results indicate that a high level of H3K9me3 could be a marker of metastasis and possibly a therapeutic target for OSCC treatment.

High expression of Sam68 contributes to metastasis by regulating vimentin expression and a motile phenotype in oral squamous cell carcinoma

The present study aimed to investigate the clinical and biological significance of Src-associated in mitosis 68 kDa (Sam68) in oral squamous cell carcinoma (OSCC). Immunohistochemical analysis was performed on tissue samples obtained from 77 patients with OSCC. Univariate analysis revealed that the high expression of Sam68 was significantly correlated with advanced pathological T stage (P=0.01), positive lymphovascular invasion (P=0.01), and pathological cervical lymph node metastasis (P<0.01). Moreover, multivariate analysis demonstrated that the high expression of Sam68 was an independent predictive factor for cervical lymph node metastasis (odds ratio, 4.39; 95% confidence interval, 1.49-14.23; P<0.01). These results indicated that high Sam68 expression contributed to tumor progression, especially cervical lymph node metastasis, in OSCC. mRNA sequencing was also performed to assess the changes in the transcriptome between OSCC cells with Sam68 knockdown and control cells with the aim of elucidating the biological roles of Sam68. Gene Ontology enrichment analysis revealed that downregulated differentially expressed genes (DEGs) were concentrated in some biological processes related to epithelial-mesenchymal transition. Among these DEGs, it was established that vimentin was particularly downregulated in these cells. It was also confirmed that Sam68 knockdown reduced the motility of OSCC cells. Furthermore, the immunohistochemical study of vimentin identified the association between vimentin expression and Sam68 expression as well as cervical lymph node metastasis. In conclusion, the present study suggested that the high expression of Sam68 may contribute to metastasis by regulating vimentin expression and a motile mesenchymal phenotype in OSCC.

Oral Cancer Cells Release Vesicles that Cause Pain

Oral cancer pain is attributed to the release from cancers of mediators that sensitize and activate sensory neurons. Intraplantar injection of conditioned media (CM) from human tongue cancer cell line HSC-3 or OSC-20 evokes nociceptive behavior. By contrast, CM from noncancer cell lines, DOK, and HaCaT are non-nociceptive. Pain mediators are carried by extracellular vesicles (EVs) released from cancer cells. Depletion of EVs from cancer cell line CM reverses mechanical allodynia and thermal hyperalgesia. CM from non-nociceptive cell lines become nociceptive when reconstituted with HSC-3 EVs. Two miRNAs (hsa-miR-21-5p and hsa-miR-221-3p) are identified that are present in increased abundance in EVs from HSC-3 and OSC-20 CM compared to HaCaT CM. The miRNA target genes suggest potential involvement in oral cancer pain of the toll like receptor 7 (TLR7) and 8 (TLR8) pathways, as well as signaling through interleukin 6 cytokine family signal transducer receptor (gp130, encoded by IL6ST) and colony stimulating factor receptor (G-CSFR, encoded by CSF3R), Janus kinase and signal transducer and activator of transcription 3 (JAK/STAT3). These studies confirm the recent discovery of the role of cancer EVs in pain and add to the repertoire of algesic and analgesic cancer pain mediators and pathways that contribute to oral cancer pain.

Roles of IGFBP-3 in cell migration and growth in an endophytic tongue squamous cell carcinoma cell line

Insulin-like growth factor binding protein-3 (IGFBP-3) is a member of the IGFBP family that has high affinity for IGFs and functions as either an oncogene or tumor suppressor in various types of cancer. We previously found that IGFBP3 mRNA levels are higher in endophytic-type human tongue squamous cell carcinoma (TSCC) that is more invasive and more prone to metastasis than exophytic and superficial types. This finding prompted us to investigate the roles of IGFBP-3 in TSCC using SAS cells, which were originally derived from endophytic-type TSCC. Specifically, we used SAS cells that express a fluorescent ubiquitination-based cell-cycle indicator (Fucci). RNA-sequencing analysis indicated that IGFBP-3 is associated with cell migration and cell growth. In fact, IGFBP-3 knockdown downregulates cell migration and causes cells to arrest in G₁. This migratory potential appears to be cell cycle–independent. IGFBP-3 knockdown also reduced levels of secreted IGFBP-3; however, decreased migratory potential was not rescued by exogenous recombinant human IGFBP-3. Furthermore, ERK activity was downregulated by IGFBP-3 depletion, which suggests that MEK/ERK signaling may be involved in IGFBP-3-mediated cell migration. We therefore conclude that intracellular IGFBP-3 enhances cell migration independently of the cell cycle in TSCC with a higher metastatic potential.

An SCPPPQ1/LAM332 protein complex enhances the adhesion and migration of oral epithelial cells: Implications for dentogingival regeneration

Common periodontal disease treatment procedures often fail to restore the structural integrity of the junctional epithelium (JE), the epithelial attachment of the gum to the tooth, leaving the tooth-gum interface prone to bacterial colonization. To address this issue, we introduced a novel bio-inspired protein complex comprised of a proline-rich enamel protein, SCPPPQ1, and laminin 332 (LAM332) to enhance the JE attachment. Using quartz crystal microbalance with dissipation monitoring (QCM-D), we showed that SCPPPQ1 and LAM332 interacted and assembled into a protein complex with high-affinity adsorption of 5.9e^-8 [M] for hydroxyapatite (HA), the main component of the mineralized tooth surfaces. We then designed a unique shear device to study the adhesion strength of the oral epithelial cells to HA. The SCPPPQ1/LAM332 complex resulted in a twofold enhancement in adhesion strength of the cells to HA compared to LAM332 (from 31 dyn/cm² to 63 dyn/cm²). In addition, using a modified wound-healing assay, we showed that gingival epithelial cells demonstrated a significantly high migration rate of 2.7 ± 0.24 µm/min over SCPPPQ1/LAM332-coated surfaces. Our collective data show that this protein complex has the potential to be further developed in designing a bioadhesive to enhance the JE attachment and protect the underlying connective tissue from bacterial invasion. However, its efficacy for wound healing requires further testing in vivo. STATEMENT OF SIGNIFICANCE: This work is the first functional study towards understanding the combined role of the enamel protein SCPPPQ1 and laminin 332 (LAM332) in the epithelial attachment of the gum, the junctional epithelium (JE), to the tooth hydroxyapatite surfaces. Such studies are essential for developing therapeutic approaches to restore the integrity of the JE in the destructive form of gum infection. We have developed a model system that provided the first evidence of the strong interaction between SCPPPQ1 and LAM332 on hydroxyapatite surfaces that favored protein adsorption and subsequently oral epithelial cell attachment and migration. Our collective data strongly suggested using the SCPPPQ1/LAM332 complex to accelerate the reestablishment of the JE after surgical gum removal to facilitate gum regeneration.

Enhanced Cytotoxic Effects in Human Oral Squamous Cell Carcinoma Cells Treated with Combined Methyltransferase Inhibitors and Histone Deacetylase Inhibitors

Combined treatment of human oral squamous cell carcinoma (OSCCs) with DNA methyltransferase inhibitors (DNMTis), histone methyltransferase inhibitors (HMTis), and histone deacetylase inhibitors (HDACis), and the molecular mechanisms underlying their anticancer effects, have not been fully elucidated. Herein, we investigated the cytotoxic effects of combined DNMTis (5-Aza-deoxycytidine: 5-Aza-dC, RG108), HMTis (3-deazaneplanocin A: DZNep), and HDACis (trichostatin A: TSA) treatment on human OSCC cells and explored their molecular mechanisms. Combined 5-Aza-dC, or RG108, and TSA treatment significantly decreased HSC-2 and Ca9-22 cell viability. Combinatorial DZNep and TSA treatment also decreased Ca9-22 cell viability. Although caspase 3/7 activation was not observed in HSC-2 cells following combined treatment, caspase activity was significantly increased in Ca9-22 cells treated with DZNep and TSA. Moreover, combined treatment with 5-Aza-dC, RG108, and TSA increased the proportion of HSC-2 and Ca9-22 cells in the S and G2/M phases. Meanwhile, increased phosphorylation of the histone variant H2A.X, a marker of double-stranded DNA breaks, was observed in both cells after combination treatment. Hence, the decreased viability induced by combined treatment with epigenomic inhibitors results from apoptosis and cell cycle arrest in S and G2/M phases. Thus, epigenomic therapy comprising combined low concentrations of DNMTi, HMTi, and HDACi is effective against OSCC.

Dual clathrin and integrin signaling systems regulate growth factor receptor activation

The crosstalk between growth factor and adhesion receptors is key for cell growth and migration. In pathological settings, these receptors are drivers of cancer. Yet, how growth and adhesion signals are spatially organized and integrated is poorly understood. Here we use quantitative fluorescence and electron microscopy to reveal a mechanism where flat clathrin lattices partition and activate growth factor signals via a coordinated response that involves crosstalk between epidermal growth factor receptor (EGFR) and the adhesion receptor β5-integrin. We show that ligand-activated EGFR, Grb2, Src, and β5-integrin are captured by clathrin coated-structures at the plasma membrane. Clathrin structures dramatically grow in response to EGF into large flat plaques and provide a signaling platform that link EGFR and β5-integrin through Src-mediated phosphorylation. Disrupting this EGFR/Src/β5-integrin axis prevents both clathrin plaque growth and dampens receptor signaling. Our study reveals a reciprocal regulation between clathrin lattices and two different receptor systems to coordinate and enhance signaling. These findings have broad implications for the regulation of growth factor signaling, adhesion, and endocytosis.

Effects of Fermented Wheat Germ Extract on Oral Cancer Cells: An In Vitro Study

Oral carcinoma is one of the most aggressive cancers, and despite the advances in the therapy, its mortality is still high. An attention in cancer treatment has focused on natural compounds due to their potential beneficial effects on human health. In this study, the effects of dietary supplement Fermented Wheat Germ Extract (FWGE) on oral tongue squamous cell carcinoma (OTSCC) cells were investigated In Vitro using three cell lines (HSC-3, SAS, SCC-25) with variable aggressiveness. The cell viability was significantly decreased by the treatment with high concentration of FWGE in every cell line. Regarding migration and invasion, HSC-3 and SCC-25 cells were most sensitive to FWGE since their movement was significantly reduced with 5 and 10 mg/ml FWGE, while SAS was inhibited only with 10 mg/ml FWGE. Chemotherapeutic compounds (cisplatin and 5-fluorouracil) significantly reduced all OTSCC cells viability. Importantly, combination of these drugs with 10 mg/ml FWGE significantly decreased the cell viability compared to the treatment with the chemotherapeutics or FWGE alone. Based on these In Vitro experiments, the use of FWGE seems to improve the anticancer effects on OTSCC cells. Further In Vivo and clinical studies should be conducted to verify the positive effects of FWGE for OTSCC patients.

Transcriptomic Profiling Predicts Multiple Pathways and Molecules Associated With the Metastatic Phenotype of Oral Cancer Cells

BACKGROUND/AIM

Metastasis to cervical lymph nodes of oral squamous cell carcinoma (OSCC) leads to a poor prognosis. The present study aimed at investigating the pathways and molecules associated with OSCC metastasis.

MATERIALS AND METHODS

The transcriptome between HSC-3 cells and their highly metastatic subline, HSC-3-M3 cells, was examined using gene expression microarray. Gene enrichment analyses and Ingenuity Pathway Analysis were performed. Kaplan-Meier plot analysis using a publicly available dataset was conducted to assess whether candidate molecules are prognosticators.

RESULTS

A total of 1,018 genes were differentially expressed, and the inflammatory pathway and NF-kB were predicted to be activated in HSC-3-M3 cells. CSF2 was suggested to be an indicator of poor prognosis in head and neck cancers.

CONCLUSION

Inflammation and NF-kB may be involved in the metastasis of OSCC, and CSF2 is a promising diagnostic and therapeutic molecule. Moreover, HSC-3-M3 cells are a useful cell line model for studying OSCC progression.

Tumor protein D52 is upregulated in oral squamous carcinoma cells under hypoxia in a hypoxia-inducible-factor-independent manner and is involved in cell death resistance

Background

Tumor protein D52 (TPD52) reportedly plays an important role in the proliferation and metastasis of various cancer cells, including oral squamous cell carcinoma (OSCC) cells, and is expressed strongly at the center of the tumor, where the microenvironment is hypoxic. Thus, the present study investigated the roles of TPD52 in the survival and death of OSCC cells under hypoxia, and the relationship with hypoxia-inducible factor (HIF). We examined the expression of TPD52 in OSCC cells under hypoxic conditions and analyzed the effects of HIF on the modulation of TPD52 expression. Finally, the combinational effects of TPD52 knockdown and HIF inhibition were investigated both in vitro and in vivo.

Results

The mRNA and protein levels of TPD52 increased in OSCC cells under hypoxia. However, the increase was independent of HIF transcription. Importantly, the observation was due to upregulation of mRNA stability by binding of mRNA to T-cell intercellular antigen (TIA) 1 and TIA-related protein (TIAR). Simultaneous knockdown of TPD52 and inhibition of HIF significantly reduced cell viability. In addition, the in vivo tumor-xenograft experiments showed that TPD52 acts as an autophagy inhibitor caused by a decrease in p62.

Conclusions

This study showed that the expression of TPD52 increases in OSCC cells under hypoxia in a HIF-independent manner and plays an important role in the proliferation and survival of the cells in concordance with HIF, suggesting that novel cancer therapeutics might be led by TPD52 suppression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-021-00634-0.

Alteration of Streptococcus salivarius in Buccal Mucosa of Oral Lichen Planus and Controlled Clinical Trial in OLP Treatment

Oral lichen planus (OLP) is a T cell-mediated common chronic inflammatory mucosal disease, with limited therapies available for long-term use. Previous study showed that ratio of genus Streptococcus decreased significantly in OLP patients when compared with controls. Buccal cotton swab samples of 43 OLP patients and 48 healthy individuals were collected for real-time quantitative polymerase chain reaction (RT-PCR) to investigate relative abundance alteration of Streptococcus salivarius in OLP lesions. Bacterial supernatants of S. salivarius ATCC® BAA-2593™ were collected by centrifugation and added to HSC-3 cells, and quantitative analysis of expression of IL-1β, IL-6, IL-8, and TNF-α in the HSC-3 cells was determined by RT-PCR. Then, a randomized, non-blinded, controlled study was conducted. Forty patients with symptomatic OLP were randomly allocated into two groups and received topical treatment of 0.1% triamcinolone acetonide dental paste (group A) and S. salivarius K12 lozenge (group B), respectively, for 4 weeks. Sign scores, visual analogue scale (VAS), and adverse reactions were recorded. Relative abundance of S. salivarius in the OLP group was lower than that of control group (P < 0.05). After treated with 0.1% supernatants of S. salivarius ATCC® BAA-2593™, the expression level of IL-6 in the HSC-3 cells significantly reduced (P < 0.001), while IL-1β, IL-8, and TNF- α showed a decreasing tendency (P > 0.05). There was significant reduction in sign scores and VAS scores in both groups after the 4-week treatment, with no significant difference between two groups. No adverse reaction was observed. S. salivarius might maintain local immune balance by inhibiting the NF-κB pathway. Topical application of Streptococcus salivarius K12 seemed to be effective in treatment of symptomatic OLP, especially with promising potential in long-term use. More detailed clinical studies with long follow-up period and standardized usage/dosage are expected to acquire definite conclusions.

EHF suppresses cancer progression by inhibiting ETS1-mediated ZEB expression

ETS homologous factor (EHF) belongs to the epithelium-specific subfamily of the E26 transformation-specific (ETS) transcription factor family. Currently, little is known about EHF’s function in cancer. We previously reported that ETS1 induces expression of the ZEB family proteins ZEB1/δEF1 and ZEB2/SIP1, which are key regulators of the epithelial–mesenchymal transition (EMT), by activating the ZEB1 promoters. We have found that EHF gene produces two transcript variants, namely a long form variant that includes exon 1 (EHF-LF) and a short form variant that excludes exon 1 (EHF-SF). Only EHF-SF abrogates ETS1-mediated activation of the ZEB1 promoter by promoting degradation of ETS1 proteins, thereby inhibiting the EMT phenotypes of cancer cells. Most importantly, we identified a novel point mutation within the conserved ETS domain of EHF, and found that EHF mutations abolish its original function while causing the EHF protein to act as a potential dominant negative, thereby enhancing metastasis in vivo. Therefore, we suggest that EHF acts as an anti-EMT factor by inhibiting the expression of ZEBs, and that EHF mutations exacerbate cancer progression.

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.

P2 purinergic receptor signaling and interleukin-1 synergistically induce interleukin-6 production in a human oral squamous carcinoma cell line

OBJECTIVES

The aim of this study was to investigate the inflammatory roles of P2 purinergic receptor (P2R) signaling in oral squamous cell carcinoma (OSCC).

METHODS

Human OSCC cell lines HSC-2, Ca9-22, and HO-1-u-1 were stimulated with P2R agonists. The concentration of interleukin (IL)-6 in culture supernatants was measured using an enzyme-linked immune sorbent assay. Expression levels of messenger RNAs (mRNAs) were analyzed using reverse transcription polymerase chain reaction. Phosphorylation of intracellular signaling molecules was analyzed using western blotting.

RESULTS

HSC-2 cells expressed the mRNAs for P2X4-6 and all P2YRs. ATP or ADP induced significantly greater production of IL-6 by HSC-2 cells. Ca9-22 cells expressed mRNAs for P2X4-6 and all P2YRs except P2Y4. ATP or ADP induced the production of IL-6 by Ca9-22 cells, but the IL-6 concentration was much lower than that in HSC-2 cells. Although HO-1-u-1 cells expressed the mRNAs for P2X4-6 and all P2YRs, ATP or ADP did not induce IL-6 production. The production of IL-6 by HSC-2 cells stimulated with adenine nucleotides was significantly inhibited by P2R antagonists and a p38 mitogen-activated protein kinase inhibitor, but not by extracellular signal-related kinase or c-Jun N-terminal kinase inhibitors. The proinflammatory cytokine IL-1 significantly augmented P2R-induced IL-6 production by HSC-2 cells via the nuclear factor-κB signaling pathway.

CONCLUSIONS

The present study suggests that P2Rs signaling and IL-1 synergistically induce chronic inflammation in OSCC. Because chronic inflammation is a well-known driving force of tumor progression, these results support therapeutic strategies that target P2Rs signaling in OSCC.

Volume-regulated chloride channel regulates cell proliferation and is involved in the possible interaction between TMEM16A and LRRC8A in human metastatic oral squamous cell carcinoma cells

OBJECTIVES

Volume-regulated anion channels (VRACs), expressed in various cells, play an important role in cell volume regulation. Despite being physiologically defined almost half a century ago, only the molecular candidates of VRAC, TMEM16A, LRRC8A, and bestrophin-1 (BEST1), are known. Here, we aimed to explore the functional significance of VRAC in, HST-1, an oral squamous cell carcinoma (OSCC) cell line.

METHODS

Cell proliferation assays, RT-PCR, Western blot, and flow cytometry were used to estimate changes in gene expression and cell proliferation. Ion channel activity was recorded using the patch-clamp technique. Specific genes were knocked-down by siRNA assays.

RESULTS

VRAC, identified as a hypotonicity-induced current, was highly functional and associated with the proliferation of HST-1 cells but not of HaCaT (a normal keratinocyte) cells. The pharmacological profile of VRAC in HST-1 was similar to that reported previously. DCPIB, a specific VRAC inhibitor, completely inhibited VRAC and proliferation of HST-1 cells, eventually leading to apoptosis. VRAC in HST-1 was attenuated by the knockdown of TMEM16A and LRRC8A, while knockdown of BEST1 affected cell proliferation. In situ proximity ligation assay showed that TMEM16A and LRRC8A co-localized under isotonic conditions (300 mOsM) but were separated under hypotonic conditions (250 mOsM) on the plasma membrane.

CONCLUSIONS

We have found that VRAC acts to regulate the proliferation of human metastatic OSCC cells and the composition of VRAC may involve in the interactions between TMEM16A and LRRC8A in HST-1 cells.

Ephrin A4-ephrin receptor A10 signaling promotes cell migration and spheroid formation by upregulating NANOG expression in oral squamous cell carcinoma cells

Ephrin type-A receptor 10 (EPHA10) has been implicated as a potential target for breast and prostate cancer therapy. However, its involvement in oral squamous cell carcinoma (OSCC) remains unclear. We demonstrated that EPHA10 supports in vivo tumor growth and lymphatic metastasis of OSCC cells. OSCC cell migration, epithelial mesenchymal transition (EMT), and sphere formation were found to be regulated by EPHA10, and EPHA10 was found to drive expression of some EMT- and stemness-associated transcription factors. Among EPHA10 ligands, exogenous ephrin A4 (EFNA4) induced the most OSCC cell migration and sphere formation, as well as up-regulation of SNAIL, NANOG, and OCT4. These effects were abolished by extracellular signal-regulated kinase (ERK) inhibition and NANOG knockdown. Also, EPHA10 was required for EFNA4-induced cell migration, sphere formation, and expression of NANOG and OCT4 mRNA. Our microarray dataset revealed that EFNA4 mRNA expression was associated with expression of NANOG and OCT4 mRNA, and OSCC patients showing high co-expression of EFNA4 with NANOG or OCT4 mRNA demonstrated poor recurrence-free survival rates. Targeting forward signaling of the EFNA4-EPHA10 axis may be a promising therapeutic approach for oral malignancies, and the combination of EFNA4 mRNA and downstream gene expression may be a useful prognostic biomarker for OSCC.

Similarities and differences in metabolites of tongue cancer cells among two- and three-dimensional cultures and xenografts

Metabolic programming of cancer cells is an essential step in transformation and tumor growth. We established two-dimensional (2D) monolayer and three-dimensional (3D) cultures, the latter called a "tissueoid cell culture system", using four types of tongue cancer cell lines. We also undertook a comprehensive metabolome analysis of three groups that included xenografts created by transplanting the cell lines into nude mice. In addition, we undertook a functional analysis of the mitochondria, which plays a key role in cancer metabolism. Principal component analysis revealed the plots of the four cell lines to be much narrower in 2D culture than in 3D culture and xenograft groups. Moreover, compared to xenografts, the 2D culture had significantly lower levels of most metabolites. These results suggest that the unique characteristics of each cell disappeared in 2D culture, and a type of metabolism unique to monolayer culture took over. Conversely, ATP production, biomass synthesis, and maintenance of redox balance were shown in 3D culture using sufficient nutrients, which closely resembled the metabolic activity in the xenografts. However, there were several differences between the metabolic activity in the 3D culture and xenografts. In vivo, the cancer tissue had blood flow with stromal cells present around the cancer cells. In the xenografts, we detected metabolized and degraded products in the liver and other organs of the host mice. Furthermore, the 3D system did not show impairment of mitochondrial function in the cancer cells, suggesting that cancer cells produce energy simultaneously through mitochondria, as well as aerobic glycolysis.

A disintegrin and metalloproteinase domain 17-epidermal growth factor receptor signaling contributes to oral cancer pain

Cancer cells secrete pronociceptive mediators that sensitize adjacent sensory neurons and cause pain. Identification and characterization of these mediators could pinpoint novel targets for cancer pain treatment. In this study, we identified candidate genes in cancer cell lines that encode for secreted or cell surface proteins that may drive nociception. To undertake this work, we used an acute cancer pain mouse model, transcriptomic analysis of publicly available human tumor-derived cell line data, and a literature review. Cancer cell line supernatants were assigned a phenotype based on evoked nociceptive behavior in an acute cancer pain mouse model. We compared gene expression data from nociceptive and nonnociceptive cell lines. Our analyses revealed differentially expressed genes and pathways; many of the identified genes were not previously associated with cancer pain signaling. Epidermal growth factor receptor (EGFR) and disintegrin metalloprotease domain 17 (ADAM17) were identified as potential targets among the differentially expressed genes. We found that the nociceptive cell lines contained significantly more ADAM17 protein in the cell culture supernatant compared to nonnociceptive cell lines. Cytoplasmic EGFR was present in almost all (>90%) tongue primary afferent neurons in mice. Monoclonal antibody against EGFR, cetuximab, inhibited cell line supernatant-induced nociceptive behavior in an acute oral cancer pain mouse model. We infer from these data that ADAM17-EGFR signaling is involved in cancer mediator-induced nociception. The differentially expressed genes and their secreted protein products may serve as candidate therapeutic targets for oral cancer pain and warrant further evaluation.

Genome-wide CRISPR screens of oral squamous cell carcinoma reveal fitness genes in the Hippo pathway

New therapeutic targets for oral squamous cell carcinoma (OSCC) are urgently needed. We conducted genome-wide CRISPR-Cas9 screens in 21 OSCC cell lines, primarily derived from Asians, to identify genetic vulnerabilities that can be explored as therapeutic targets. We identify known and novel fitness genes and demonstrate that many previously identified OSCC-related cancer genes are non-essential and could have limited therapeutic value, while other fitness genes warrant further investigation for their potential as therapeutic targets. We validate a distinctive dependency on YAP1 and WWTR1 of the Hippo pathway, where the lost-of-fitness effect of one paralog can be compensated only in a subset of lines. We also discover that OSCCs with WWTR1 dependency signature are significantly associated with biomarkers of favorable response toward immunotherapy. In summary, we have delineated the genetic vulnerabilities of OSCC, enabling the prioritization of therapeutic targets for further exploration, including the targeting of YAP1 and WWTR1.

Application of "Tissueoid Cell Culture System" Using a Silicate Fiber Scaffold for Cancer Research

BACKGROUND

We developed a 3-dimensional (3D) culture system using a high-purity silica fiber scaffold of unwoven sheets called CellbedTM.

METHODS

We used adherent colon and esophagogastric junction adenocarcinoma cells, tongue squamous cell carcinoma (SqCC) cells, and nonadherent gastric cancer cells. These cells were subjected to staining with various substances and observed by electron microscopy. To evaluate the effects of extracellular matrix in carcinoma tissues, SqCC cells were cultured in Cellbed coated with collagens I, III, and IV.

RESULTS

Especially well-differentiated carcinoma cells cultured in this 3D system showed their own unique characteristics: luminal formation in adenocarcinoma cells and cell stratification and keratinization in SqCC cells. Scanning electron microscopy revealed the proliferation of cancer cells with cytoplasm entwined in Cellbed. Intercellular desmosomes in squamous epithelia were detected by transmission electron microscopy of vertical cross sections. SqCC cells cultured in Cellbed coated with collagen IV showed enhanced invasive and proliferative abilities.

CONCLUSION

Because the morphology of cancer cells cultured in this 3D culture system is similar to that in living organisms, we called the system a "tissueoid cell culture system." Coating with collagen IV enables the modification of cell-matrix interactions as well as recapitulation of the in vivo microenvironment.

GANT61 Reduces Hedgehog Molecule (GLI1) Expression and Promotes Apoptosis in Metastatic Oral Squamous Cell Carcinoma Cells

Due to its importance in the pathogenesis of oral squamous cell carcinoma (OSCC), the Hedgehog (HH) pathway is considered a potential therapeutic target. We investigated the effects of GANT61, a GLI inhibitor, on HH gene expression, as well as on metastatic OSCC cell proliferation and death. Following culture in DMEM medium, cytotoxicity of GANT61 against different tumor and non-tumor cell types was assessed by alamarBlue assays. Cytotoxicity analysis revealed that the metastatic HSC3 cell line was the most sensitive (IC₅₀: 36 µM) to the tested compound. The compound’s effects on the expression of HH pathways components were analyzed by qPCR and Western blot; cell viability was analyzed by trypan blue assay and flow cytometry were used to investigate cell cycle phase, morphology, and death patterns in HSC3 cells. A significant reduction in mRNA levels of the GLI1 transcription factor was found after 12 h of treatment withGANT61. Protein expression levels of other HH pathway components (PTCH1, SHH, and Gli1) and HSC3 cell viability also decreased after 24 h of treatment. Cell cycle analysis and death pattern evaluations revealed significantly increased nuclear fragmentation in sub-G1 phase, as well as cell death due to apoptosis. In conclusion, the significantly reduced GLI1 gene expression seen in response to the GLI inhibitor indicates diminished downstream activation in HH pathway components. GANT61 significantly reduced cell viability in the metastatic cell line of OSCC and promoted a significant increase in nuclear fragmentation and cell death by apoptosis.

Quantitative analyses of EGFR localization and trafficking dynamics in the follicular epithelium

To bridge the gap between qualitative and quantitative analyses of the epidermal growth factor receptor (EGFR) in tissues, we generated an sfGFP-tagged EGF receptor (EGFR-sfGFP) in Drosophila The homozygous fly appears similar to wild type with EGFR expression and activation patterns that are consistent with previous reports in the ovary, early embryo, and imaginal discs. Using ELISA, we quantified an average of 1100, 6200 and 2500 receptors per follicle cell (FC) at stages 8/9, 10 and ≥11 of oogenesis, respectively. Interestingly, the spatial localization of the EGFR to the apical side of the FCs at early stages depended on the TGFα-like ligand Gurken. At later stages, EGFR localized to basolateral positions of the FCs. Finally, we followed the endosomal localization of EGFR in the FCs. The EGFR colocalized with the late endosome, but no significant colocalization of the receptor was found with the early endosome. The EGFR-sfGFP fly is an exciting new resource for studying cellular localization and regulation of EGFR in tissues.

Preclinical Assessment of the Effectiveness of Magnetic Resonance Molecular Imaging of Extradomain-B Fibronectin for Detection and Characterization of Oral Cancer

PURPOSE

Oral squamous cell carcinoma (OSCC) has not seen a substantial improvement in patient survival despite therapeutic advances, making accurate detection and characterization of the disease a clinical priority. Here, we aim to demonstrate the effectiveness of magnetic resonance imaging (MRI) with the targeted MRI contrast agent MT218 specific to extradomain-B fibronectin (EDB-FN) in the tumor microenvironment for detection and characterization of aggressive OSCC tumors.

PROCEDURES

EDB-FN expression was evaluated in human normal tongue and OSCC specimens with immunohistochemistry. Invasiveness of human CAL27, HSC3, and SCC4 OSCC cells was analyzed with spheroid formation and transwell assays. EDB-FN expression in the cells was analyzed with semiquantitative real-time PCR, western blotting, and a peptide binding study with confocal microscopy. Contrast-enhanced MRI with MT218 was performed on subcutaneous OSCC mouse models at a dose of 0.04 mmol/kg, using gadoteridol (0.1 mmol/kg) as a control.

RESULTS

Strong EDB-FN expression was observed in human untreated primary and metastatic OSCC, reduced expression in treated OSCC, and little expression in normal tongue tissue. SCC4 and HSC3 cell lines demonstrated high invasive potential with high and moderate-EDB-FN expression, respectively, while CAL27 showed little invasive potential and low-EDB-FN expression. In T₁-weighted MRI, MT218 produced differential contrast enhancement in the subcutaneous tumor models in correlation with EDB-FN expression in the cancer cells. Enhancement in the high-EDB-FN tumors was greater with MT218 at 0.04 mmol/kg than gadoteridol at 0.1 mmol/kg.

CONCLUSIONS

The results suggest EDB-FN has strong potential as an imageable biomarker for aggressive OSCC. MRMI results demonstrate the effectiveness of MT218 and the potential for differential diagnostic imaging of oral cancer for improving the management of the disease.

AIRE is induced in oral squamous cell carcinoma and promotes cancer gene expression

Autoimmune regulator (AIRE) is a transcriptional regulator that is primarily expressed in medullary epithelial cells, where it induces tissue-specific antigen expression. Under pathological conditions, AIRE expression is induced in epidermal cells and promotes skin tumor development. This study aimed to clarify the role of AIRE in the pathogenesis of oral squamous cell carcinoma (OSCC). AIRE expression was evaluated in six OSCC cell lines and in OSCC tissue specimens. Expression of STAT1, ICAM1, CXCL10, CXCL11, and MMP9 was elevated in 293A cells stably expressing AIRE, and conversely, was decreased in AIRE-knockout HSC3 OSCC cells when compared to the respective controls. Upregulation of STAT1, and ICAM in OSCC cells was confirmed in tissue specimens by immunohistochemistry. We provide evidence that AIRE exerts transcriptional control in cooperation with ETS1. Expression of STAT1, ICAM1, CXCL10, CXCL11, and MMP9 was increased in 293A cells upon Ets1 transfection, and coexpression of AIRE further increased the expression of these proteins. AIRE coprecipitated with ETS1 in a modified immunoprecipitation assay using formaldehyde crosslinking. Chromatin immunoprecipitation and quantitative PCR analysis revealed that promoter fragments of STAT1, ICAM1, CXCL10, and MMP9 were enriched in the AIRE precipitates. These results indicate that AIRE is induced in OSCC and supports cancer-related gene expression in cooperation with ETS1. This is a novel function of AIRE in extrathymic tissues under the pathological condition.

Addiction of mesenchymal phenotypes on the FGF/FGFR axis in oral squamous cell carcinoma cells

The epithelial–mesenchymal transition (EMT) is a crucial morphological event that occurs during epithelial tumor progression. ZEB1/2 are EMT transcription factors that are positively correlated with EMT phenotypes and breast cancer aggressiveness. ZEB1/2 regulate the alternative splicing and hence isoform switching of fibroblast growth factor receptors (FGFRs) by repressing the epithelial splicing regulatory proteins, ESRP1 and ESRP2. Here, we show that the mesenchymal-like phenotypes of oral squamous cell carcinoma (OSCC) cells are dependent on autocrine FGF–FGFR signaling. Mesenchymal-like OSCC cells express low levels of ESRP1/2 and high levels of ZEB1/2, resulting in constitutive expression of the IIIc-isoform of FGFR, FGFR(IIIc). By contrast, epithelial-like OSCC cells showed opposite expression profiles for these proteins and constitutive expression of the IIIb-isoform of FGFR2, FGFR2(IIIb). Importantly, ERK1/2 was constitutively phosphorylated through FGFR1(IIIc), which was activated by factors secreted autonomously by mesenchymal-like OSCC cells and involved in sustained high-level expression of ZEB1. Antagonizing FGFR1 with either inhibitors or siRNAs considerably repressed ZEB1 expression and restored epithelial-like traits. Therefore, autocrine FGF–FGFR(IIIc) signaling appears to be responsible for sustaining ZEB1/2 at high levels and the EMT phenotype in OSCC cells.

CD206+ tumor-associated macrophages promote proliferation and invasion in oral squamous cell carcinoma via EGF production

Tumor-associated macrophages (TAMs) promote tumor progression and inhibit anti-tumor immune response by producing various mediators and preferentially express CD163, CD204, and CD206. However, the role of these TAM subsets in oral squamous cell carcinoma (OSCC) remains unclear. Here we investigated the expression and function of TAM subsets in OSCC, especially in cancer cell proliferation. Biopsy sample from 44 patients with OSCC were examined for the expression of TAM markers and EGF by immunohistochemistry. EGF production of TAM subsets isolated from OSCC patients was assessed by flow cytometry. We also examined the effect of conditioned medium from TAM subsets on the proliferation of OSCC cells. CD163⁺ cells were detected diffusely all over the tumor and connective tissue area, while CD204⁺ and CD206⁺ cells were mainly detected in/around the tumors. Flow cytometric analysis found that CD206⁺ TAMs strongly produced EGF compared with CD163⁺ and CD204⁺ TAMs. Cell proliferation and invasion of OSCC cells cultured with conditioned medium of CD206⁺ TAMs were strongly enhanced and inhibited by anti-EGFR. The number of CD206⁺ TAMs positively correlated with worse clinical prognosis. Our results revealed differences in localization and EGF production among these TAM subsets. CD206⁺ TAMs might play a critical role in the proliferation of OSCC via EGF production.

Inhibition of UCH-L1 Deubiquitinating Activity with Two Forms of LDN-57444 Has Anti-Invasive Effects in Metastatic Carcinoma Cells

Normally ubiquitin C-terminal hydrolase L1 (UCH-L1) is expressed in the central nervous and reproductive systems of adults, but its de novo expression has been detected in many human cancers. There is a growing body of evidence that UCH-L1 de-ubiquitinating (DUB) activity plays a major pro-metastatic role in certain carcinomas. Here we tested anti-metastatic effects of the small-molecule inhibitor of UCH-L1 DUB activity, LDN-57444, in cell lines from advanced oral squamous cell carcinoma (OSCC) as well as invasive nasopharyngeal (NP) cell lines expressing the major pro-metastatic gene product of Epstein–Barr virus (EBV) tumor virus, LMP1. To overcome the limited aqueous solubility of LDN-57444 we developed a nanoparticle formulation of LDN-57444 by incorporation of the compound in polyoxazoline micellear nanoparticles (LDN-POx). LDN-POx nanoparticles were equal in effects as the native compound in vitro. Our results demonstrate that inhibition of UCH-L1 DUB activity with LDN or LDN-POx inhibits secretion of exosomes and reduces levels of the pro-metastatic factor in exosomal fractions. Both forms of UCH-L1 DUB inhibitor suppress motility of metastatic squamous carcinoma cells as well as nasopharyngeal cells expressing EBV pro-metastatic Latent membrane protein 1 (LMP1) in physiological assays. Moreover, treatment with LDN and LDN-POx resulted in reduced levels of pro-metastatic markers, a decrease of carcinoma cell adhesion, as well as inhibition of extra-cellular vesicle (ECV)-mediated transfer of viral invasive factor LMP1. We suggest that soluble inhibitors of UCH-L1 such as LDN-POx offer potential forms of treatment for invasive carcinomas including EBV-positive malignancies.

Mechanism for oral tumor cell lysyl oxidase like-2 in cancer development: synergy with PDGF-AB

Extracellular lysyl oxidases (LOX and LOXL1–LOXL4) are critical for collagen biosynthesis. LOXL2 is a marker of poor survival in oral squamous cell cancer. We investigated mechanisms by which tumor cell secreted LOXL2 targets proximal mesenchymal cells to enhance tumor growth and metastasis. This study identified the first molecular mechanism for LOXL2 in the promotion of cancer via its enzymatic modification of a non-collagenous substrate in the context of paracrine signaling between tumor cells and resident fibroblasts. The role and mechanism of active LOXL2 in promoting oral cancer was evaluated and employed a novel LOXL2 small molecule inhibitor, PSX-S1C, administered to immunodeficient, and syngeneic immunocompetent orthotopic oral cancer mouse models. Tumor growth, histopathology, and metastases were monitored. In vitro mechanistic studies with conditioned tumor cell medium treatment of normal human oral fibroblasts were carried out in the presence and absence of the LOXL2 inhibitor to identify signaling mechanisms promoted by LOXL2 activity. Inhibition of LOXL2 attenuated cancer growth and lymph node metastases in the orthotopic tongue mouse models. Immunohistochemistry data indicated that LOXL2 expression in and around tumors was decreased in mice treated with the inhibitor. Inhibition of LOXL2 activity by administration of PXS-S1C to mice reduced tumor cell proliferation, accompanied by changes in morphology and in the expression of epithelial to mesenchymal transition markers. In vitro studies identified PDGFRβ as a direct substrate for LOXL2, and indicated that LOXL2 and PDGF-AB together secreted by tumor cells optimally activated PDGFRβ in fibroblasts to promote proliferation and the tendency toward fibrosis via ERK activation, but not AKT. Optimal fibroblast proliferation in vitro required LOXL2 activity, while tumor cell proliferation did not. Thus, tumor cell-derived LOXL2 in the microenvironment directly targets neighboring resident cells to promote a permissive local niche, in addition to its known role in collagen maturation.

Functional genomics screen with pooled shRNA library and gene expression profiling with extracts of Azadirachta indica identify potential pathways for therapeutic targets in head and neck squamous cell carcinoma

Tumor suppression by the extracts of Azadirachta indica (neem) works via anti-proliferation, cell cycle arrest, and apoptosis, demonstrated previously using cancer cell lines and live animal models. However, very little is known about the molecular targets and pathways that neem extracts and their associated compounds act through. Here, we address this using a genome-wide functional pooled shRNA screen on head and neck squamous cell carcinoma cell lines treated with crude neem leaf extracts, known for their anti-tumorigenic activity. We analyzed differences in global clonal sizes of the shRNA-infected cells cultured under no treatment and treatment with neem leaf extract conditions, assayed using next-generation sequencing. We found 225 genes affected the cancer cell growth in the shRNA-infected cells treated with neem extract. Pathway enrichment analyses of whole-genome gene expression data from cells temporally treated with neem extract revealed important roles played by the TGF-β pathway and HSF-1-related gene network. Our results indicate that neem extract affects various important molecular signaling pathways in head and neck cancer cells, some of which may be therapeutic targets for this devastating tumor.

Matrix metalloproteinase 9 inhibits the motility of highly aggressive HSC-3 oral squamous cell carcinoma cells

Pro-tumorigenic activities of matrix metalloproteinase (MMP) 9 have been linked to many cancers, but recently the tumour-suppressing role of MMP9 has also been elucidated. The multifaceted evidence on this subject prompted us to examine the role of MMP9 in the behaviour of oral tongue squamous cell carcinoma (OTSCC) cells. We used gelatinase-specific inhibitor, CTT2, and short hairpin (sh) RNA gene silencing to study the effects of MMP9 on proliferation, motility and invasion of an aggressive OTSCC cell line, HSC-3. We found that the migration and invasion of HSC-3 cells were increased by CTT2 and shRNA silencing of MMP9. Proliferation, in turn, was decreased by MMP9 inhibition. Furthermore, arresten-overexpressing HSC-3 cells expressed increased levels of MMP9, but exhibited decreased motility compared with controls. Interestingly, these cells restored their migratory capabilities by CTT2 inhibition of MMP9. Hence, although higher MMP9 expression could give rise to an increased tumour growth in vivo due to increased proliferation, in some circumstances, it may participate in yet unidentified molecular mechanisms that reduce the cell movement in OTSCC.

Treatment with Lactobacillus Retards the Tumor Growth of Head and Neck Squamous Cell Carcinoma Cells Inoculated in Mice

Bacteria have been used for more than a century to treat solid tumors. Because solid tumors generate an anaerobic environment, we evaluated the anti-tumor effect of the obligate anaerobe strain KK378, derived from Lactobacillus casei (L. casei), using mice bearing head and neck cancer. Wild-type L. casei is a nonpathogenic bacterium that is commonly used in foods. Moreover, patients with head and neck squamous cell carcinoma often have multiple cancers and cervical lymph node metastasis that can be directly sensed beneath the skin. To establish the animal model bearing head and neck cancer, we inoculated each of human squamous cell carcinoma cell lines, SAS, HSQ89, and HSC2, on the back skin of BALB/cSlc-nu/nu mice. After tumor formation, L. casei KK378 was administered directly into the tumor, and tumor size and serum cytokine levels were analyzed. Mice injected with 10⁸ cfu of L. casei KK378 showed reduction in tumor growth compared with PBS control; especially, the SAS tumor was significantly reduced (p = 0.008). Administered L. casei KK378 was detected in tumor tissues but not in normal tissues (liver, kidney, and lung) of SAS tumor-bearing mice, which was associated with increased blood cytokines (TNF-α, IFN-γ, IL-5, IL-10, and IL-12). Among these cytokines, the serum levels of IFN-γ and TNF-α were significantly increased (p < 0.05). In conclusion, L. casei KK378 infection may suppress tumor growth by inducing the host immune response. Direct injection of Lactobacillus into the tumor could be a potential strategy to treat head and neck squamous cell carcinoma.

Exosomes derived from HIV-1-infected cells promote growth and progression of cancer via HIV TAR RNA

People living with HIV/AIDS on antiretroviral therapy have increased risk of non-AIDS-defining cancers (NADCs). However, the underlying mechanism for development and progression of certain NADCs remains obscure. Here we show that exosomes released from HIV-infected T cells and those purified from blood of HIV-positive patients stimulate proliferation, migration and invasion of oral/oropharyngeal and lung cancer cells. The HIV transactivation response (TAR) element RNA in HIV-infected T-cell exosomes is responsible for promoting cancer cell proliferation and inducing expression of proto-oncogenes and Toll-like receptor 3 (TLR3)-inducible genes. These effects depend on the loop/bulge region of the molecule. HIV-infected T-cell exosomes rapidly enter recipient cells through epidermal growth factor receptor (EGFR) and stimulate ERK1/2 phosphorylation via the EGFR/TLR3 axis. Thus, our findings indicate that TAR RNA-containing exosomes from HIV-infected T cells promote growth and progression of particular NADCs through activation of the ERK cascade in an EGFR/TLR3-dependent manner.

HIV patients have an increased risk of developing non-AIDS-defining cancers but the molecular mechanisms underlying this predisposition are unclear. Here the authors show that exosomes secreted by HIV-infected T cells or isolated from the blood of HIV-positive patients, stimulate oncogenic properties of cancer cells through the activation of ERK1/2 signaling pathway.