Up-regulation of TNF-alpha/NFkB/SIRT1 axis drives aggressiveness and cancer stem cells accumulation in chemoresistant oral squamous cell carcinoma

Tumor resistance remains an obstacle to successfully treating oral squamous cell carcinoma (OSCC). Cisplatin is widely used as a cytotoxic drug to treat solid tumors, including advanced OSCC, but with low efficacy due to chemoresistance. Therefore, identifying the pathways that contribute to chemoresistance may show new possibilities for improving the treatment. This work explored the role of the tumor necrosis factor-alpha (TNF-alpha)/NFkB signaling in driving the cisplatin resistance of OSCC and its potential as a pharmacological target to overcome chemoresistance. Differential accessibility analysis demonstrated the enrichment of opened chromatin regions in members of the TNF-alpha/NFkB signaling pathway, and RNA-Seq confirmed the upregulation of TNF-alpha/NFkB signaling in cisplatin-resistant cell lines. NFkB was accumulated in cisplatin-resistant cell lines and in cancer stem cells (CSC), and the administration of TNF-alpha increased the CSC, suggesting that TNF-alpha/NFkB signaling is involved in the accumulation of CSC. TNF-alpha stimulation also increased the histone deacetylases HDAC1 and SIRT1. Cisplatin-resistant cell lines were sensitive to the pharmacological inhibition of NFkB, and low doses of the NFkB inhibitors, CBL0137, and emetine, efficiently reduced the CSC and the levels of SIRT1, increasing histone acetylation. The NFkB inhibitors decreased stemness potential, clonogenicity, migration, and invasion of cisplatin-resistant cell lines. The administration of the emetine significantly reduced the tumor growth of cisplatin-resistant xenograft models, decreasing NFkB and SIRT1, increasing histone acetylation, and decreasing CSC. TNF-alpha/NFkB/SIRT1 signaling regulates the epigenetic machinery by modulating histone acetylation, CSC, and aggressiveness of cisplatin-resistant OSCC and the NFkB inhibition is a potential strategy to treat chemoresistant OSCC.

Clock gene Per2 modulates epidermal tissue repair in vivo

Wound healing can be influenced by genes that control the circadian cycle, including Per2 and BMAL1, which coordinate the functions of several organs, including the skin. The aim of the study was to evaluate the role of PER2 during experimental skin wound healing. Two groups (control and Per2-KO), consisting of 14 male mice each, were anesthetized by inhalation, and two 6 mm wounds were created on their dorsal skin using a punch biopsy. A silicone ring was sutured around the wound perimeter to restrict contraction. The wound healing process was clinically measured daily (closure index) until complete wound repair. On Day 6, histomorphometric analysis was performed using the length and thickness of the epithelial migration tongue, in addition to counting vessels underlying the lesion by immunofluorescence assay and maturation of collagen fibers through picrosirius staining. Bromodeoxyuridine (BrdU) incorporation and quantification were performed using the subcutaneous injection technique 2 h before euthanasia and through immunohistochemical analysis of the proliferative index. In addition, the qualitative analysis of myofibroblasts and periostin distribution in connective tissue was performed by immunofluorescence. Statistically significant differences were observed in the healing time between the experimental groups (means: 15.5 days for control mice and 13.5 days for Per2-KO; p = 0.001). The accelerated healing observed in the Per2-KO group (p < 0.05) was accompanied by statistical differences in wound diameter and length of the migrating epithelial tongue (p = 0.01) compared to the control group. Regarding BrdU immunoreactivity, higher expression was observed in the intact epithelium of Per2-KO animals (p = 0.01), and this difference compared to control was also present, to a lesser extent, at the wound site (p = 0.03). Immunofluorescence in the connective tissue underlying the wound showed a higher angiogenic potential in the Per2-KO group in the intact tissue area and the wound region (p < 0.01), where increased expression of myofibroblasts was also observed. Qualitative analysis revealed the distribution of periostin protein and collagen fibers in the connective tissue underlying the wound, with greater organization and maturation during the analyzed period. Our research showed that the absence of the Per2 gene positively impacts the healing time of the skin in vivo. This acceleration depends on the increase of epithelial proliferative and angiogenic capacity of cells carrying the Per2 deletion.

Oral squamous cell carcinoma cancer stem cells have different drug sensitive to pharmacological NFκB and histone deacetylation inhibition

Despite many progresses in the development of new systemic therapies for oral squamous cell carcinoma (OSCC), the five-year survival rate of OSCC is low. The traditional chemotherapies approach (cisplatin - CDDP) shows some limitations like drug toxicity, limited efficacy, and drug resistance. Promising studies suggested OSCC cancer stem cells (CSC) presented resistance to CDDP. We have previously studied many targets, and we extensively showed the efficacy of the NFκB signaling and the role of histones acetylation, on different malignant tumors, including adenoid cystic carcinoma and mucoepidermoid carcinoma, but until then the effects of the NFkB inhibitor and histone deacetylase (HDAC) inhibitor on the biology of OSCC were not evaluated. Here we assessed the pharmacological inhibitor of NFκB emetine and HDAC inhibitor SAHA on the behavior of CSC derived from OSCC. Our data suggested that CDDP administration resulted in reduced viability of bulk OSCC cells and increased CSC. A single and isolated shot of emetine and SAHA were able to disrupt CSC by inhibiting the NFκB pathway and increasing the histone acetylation levels, respectively. Further, the combined administration of emetine and SAHA presented the same CSC disruption as seen in emetine alone.

Proposal of a secure and efficient protocol for a murine oral carcinogenesis model induced by 4-nitroquinoline-1-oxide (4NQO)

An important rat model using the chemical carcinogen 4-nitroquinoline-1-oxide (4NQO) has been described for the study of the process of oral carcinogenesis. This model replicates the gradual progression seen in oral carcinoma patients. However, due to its high level of toxicity, its use in fundamental research is challenging. Here, we propose a secure and efficient modified protocol based on a lower dose of 4NQO concentration as well as an increased water supply and hypercaloric diet, in order to reduce the damage caused to the animals during the process of oral carcinogenesis. Twenty-two male Wistar rats were exposed to 4NQO, evaluated clinically once a week and euthanized at 12 and 20 weeks for histopathological analysis. The protocol involves a staggered dose of 4NQO up to a concentration of 25 ppm, associated with two days of pure water, a 5% glucose solution once a week and a hypercaloric diet. This modified protocol prevents the immediate consequences of the carcinogen. At week 7, all animals displayed clinically evident tongue lesions. From a histological perspective, after 12 weeks of 4NQO exposure, 72.7% of the animals developed epithelial dysplasia and 27.3% developed in situ carcinoma. In the group exposed for 20 weeks, epithelial dysplasia and in situ carcinoma were diagnosed in one case each, whereas invasive carcinoma was diagnosed in 81.8% of the cases. Nonsignificant modification of animal's behavior and weight was observed. This new proposed 4NQO protocol was secure and effective for studying oral carcinogenesis and can be used to conduct lengthy investigations.

New Insights into the Impact of Human Papillomavirus on Oral Cancer in Young Patients: Proteomic Approach Reveals a Novel Role for S100A8

Human papillomavirus (HPV) infection has recently been linked to a subset of cancers affecting the oral cavity. However, the molecular mechanisms underlying HPV-driven oral squamous cell carcinoma (OSCC) onset and progression are poorly understood.

METHODS

We performed MS-based proteomics profiling based on HPV status in OSCC in young patients, following biological characterization and cell assays to explore the proteome functional landscape.

RESULTS

Thirty-nine proteins are differentially abundant between HPV (+) and HPV (-) OSCC. Among them, COPS3, DYHC1, and S100A8 are unfavorable for tumor recurrence and survival, in contrast to A2M and Serpine1, low levels of which show an association with better DFS. Remarkably, S100A8 is considered an independent prognostic factor for lower survival rates, and at high levels, it alters tumor-associated immune profiling, showing a lower proportion of M1 macrophages and dendritic cells. HPV (+) OSCC also displayed the pathogen-associated patterns receptor that, when activated, triggered the S100A8 and NFκB inflammatory responses.

CONCLUSION

HPV (+) OSCC has a peculiar microenvironment pattern distinctive from HPV (-), involving the expression of pathogen-associated pattern receptors, S100A8 overexpression, and NFκB activation and responses, which has important consequences in prognosis and may guide therapeutic decisions.

Inflammatory Cells Can Alter the Levels of H3K9ac and γH2AX in Dysplastic Cells and Favor Tumor Phenotype

Oral potentially malignant disorders (OPMD) are clinical presentations that carry an increased risk of cancer development. Currently, epithelial dysplasia grade is based on architectural and cytological epithelial changes and is used to predict the malignant transformation of these lesions. However, predicting which OPMD will progress to a malignant tumor is very challenging. Inflammatory infiltrates can favor cancer development, and recent studies suggest that this association with OPMD lesions may be related to the etiology and/or aggressive clinical behavior of these lesions. Epigenetic changes such as histone modifications may mediate chronic inflammation and also favor tumor cells in immune resistance and evasion. This study aimed to evaluate the relationship between histone acetylation (H3K9ac) and DNA damage in the context of dysplastic lesions with prominent chronic inflammation. Immunofluorescence of "low-risk" and "high-risk" OPMD lesions (n = 24) and inflammatory fibrous hyperplasia (n = 10) as the control group was performed to assess histone acetylation levels and DNA damage through the phosphorylation of H2AX (γH2AX). Cell co-culture assays with PBMCs and oral keratinocyte cell lines (NOK-SI, DOK, and SCC-25) were performed to assess proliferation, adhesion, migration, and epithelial-mesenchymal transition (EMT). Oral dysplastic lesions showed a hypoacetylation of H3K9 and low levels of γH2AX compared to control. The contact of dysplastic oral keratinocytes with PBMCs favored EMT and the loss of cell-cell adhesion. On the other hand, p27 levels increased and cyclin E decreased in DOK, indicating cell cycle arrest. We conclude that the presence of chronic inflammation associated to dysplastic lesions is capable of promoting epigenetic alterations, which in turn can favor the process of malignant transformation.

High density of CD8 T cell and immune imbalance of T lymphocytes subsets are associated with proliferative verrucous leukoplakia

Oral leukoplakia (OL) and proliferative verrucous leukoplakia (PVL) are oral potentially malignant disorders (OPMDs) that microscopically show no or varying degrees of dysplasia. Even sharing clinical and microscopic aspects, PVL shows a more aggressive clinical behaviour, with a malignant transformation rate greater than 40%. Inflammatory infiltrate associated with dysplastic lesions may favour malignant transformation of OPMDs. This study aimed to evaluate the density of T cells and cytokines in dysplastic lesions from OL and PVL patients. Additionally, we evaluated whether soluble products produced in vitro by dysplastic keratinocytes are capable of modulating apoptosis rates and Th phenotype (Th1, Th2, Th17 and Treg) of peripheral blood mononuclear cells. The density of CD3, CD4 and CD8 T cells was assessed by immunohistochemistry. Cytokines and chemokines profile from frozen tissue samples were analysed using the LUMINEX system. Apoptosis rates and Th phenotype modulation were evaluated by flow cytometry. Our results showed an increase in the number of CD8 T cell in the subepithelial region from PVL dysplastic lesions in relation to OL samples. PVL showed increased levels of IL-5 and a decrease in IL-1β and IFN-γ levels compared to OL. Soluble products of PVL and oral carcinoma cell cultures were able to reduce apoptosis rate and promote an imbalance of Th1/Th2 and Th17/Treg. The high-subepithelial density of CD8 T cells and immune imbalance of T lymphocytes subsets probably play an important role in the pathogenesis of PVL and may explain its more aggressive behaviour in relation to OL.

Repurposing NFκB and HDAC inhibitors to individually target cancer stem cells and non-cancer stem cells from mucoepidermoid carcinomas

Drug resistance remains a major obstacle in the treatment of mucoepidermoid carcinomas (MEC) leading to tumor recurrence, disease progression, and metastasis. Emerging evidence suggests that drug resistance is mediated by the presence of a highly adaptative subpopulation of cancer cells known as cancer stem cells (CSC). We have previously reported that solid tumors use NFkB signaling as a chemotherapy-resistant mechanism. We have also shown that interfering with the epigenome of solid tumors is an effective strategy to control the population of CSC. Here, we sought to investigate the effects of the NFkB inhibitor emetine and the HDAC inhibitor SAHA on the biology of MEC CSC and assessed whether this combination therapy would favor the standard of care therapy comprised of the administration of Cisplatin (CDDP). Our findings suggested that the administration of low concentrations of emetine and SAHA is more effective in disrupting CSC in MEC, while the administration of emetine in combination with CDDP constitutes an effective therapy to target non-CSC MEC tumor cells.

Expression profile of the PI3K-AKT-mTOR pathway in head and neck squamous cell carcinoma: Data from Brazilian population

OBJECTIVE

The phosphatidylinositol 3-kinase/protein kinase-B/mammalian target of the rapamycin (PI3K-AKT-mTOR) signaling pathway is an important regulator of cell proliferation, survival, and motility. The gain or loss of function of proteins related to this pathway results in the neoplastic transformation in several types of cancers. This study aimed to evaluate the expression profile of the PI3K-AKT-mTOR pathway in patients with head and neck squamous cell carcinoma (HNSCC) and HNSCC cell lines.

STUDY DESIGN

The study involved 26 formalin-fixed paraffin-embedded tissue samples from patients with HNSCC. The analysis of immunohistochemical expression of PI3K, AKT, p-mTOR, and phosphatase and tensin homolog (PTEN) proteins was performed by a quantitative assessment. The in vitro gene and protein expression evaluation was performed by real-time polymerase chain reaction and Western blot assay, respectively, in the human cell lines SCC-9 and FaDu.

RESULTS

High levels of PI3K, AKT, and p-mTOR were found in most HNSCC tumors. Following this result, we observed low amounts or absence of PTEN in most samples. Additionally, the FaDu cells (pharynx) showed higher AKT expression but lower expression of p-mTOR compared with SCC-9 cells (oral cavity), which hints at a loco-anatomical relevance.

CONCLUSION

Overall, this study found increased expression of the PI3K-AKT-mTOR pathway along with evident PTEN reduction in head and neck cancer.

Tensile Strength Essay Comparing Three Different Platelet-Rich Fibrin Membranes (L-PRF, A-PRF, and A-PRF+): A Mechanical and Structural In Vitro Evaluation

Predictable outcomes intended by the application of PRF (platelet-rich fibrin) derivative membranes have created a lack of consideration for their consistency and functional integrity. This study aimed to compare the mechanical properties through tensile strength and analyze the structural organization among the membranes produced by L-PRF (leukocyte platelet-rich fibrin), A-PRF (advanced platelet-rich fibrin), and A-PRF+ (advanced platelet-rich fibrin plus) (original protocols) that varied in centrifugation speed and time. L-PRF (n = 12), A-PRF (n = 19), and A-PRF+ (n = 13) membranes were submitted to a traction test, evaluating the maximum and average traction. For maximum traction, 0.0020, 0.0022, and 0.0010 N·mm−2 were obtained for A-PRF, A-PRF+, and L-PRF, respectively; regarding the average resistance to traction, 0.0012, 0.0015, and 0.006 N·mm−2 were obtained, respectively (A-PRF+ > A-PRF > L-PRF). For all groups studied, significant results were found. In the surface morphology observations through SEM, the L-PRF matrix showed a highly compact surface with thick fibers present within interfibrous areas with the apparent destruction of red blood cells and leukocytes. The A-PRF protocol showed a dense matrix composed of thin and elongated fibers that seemed to follow a preferential and orientated direction in which the platelets were well-adhered. Porosity was also evident with a large diameter of the interfibrous spaces whereas A-PRF+ was the most porous platelet concentrate with the greatest fiber abundance and cell preservation. Thus, this study concluded that A-PRF+ produced membranes with significant and higher maximum traction results, indicating a better viscoelastic strength when stretched by two opposing forces.

Cephaeline is an inductor of histone H3 acetylation and inhibitor of mucoepidermoid carcinoma cancer stem cells

AIM

To evaluate the potential use of Cephaeline as a therapeutic strategy to manage mucoepidermoid carcinomas (MEC) of the salivary glands.

MATERIAL AND METHODS

UM-HMC-1, UM-HMC-2, and UM-HMC-3A MEC cell lines were used to establish the effects of Cephaeline over tumor viability determined by MTT assay. In vitro wound healing scratch assays were performed to address cellular migration while immunofluorescence staining for histone H3 lysine 9 (H3k9ac) was used to identify the acetylation status of tumor cells upon Cephaeline administration. The presence of cancer stem cells was evaluated by the identification of ALDH enzymatic activity by flow cytometry and through functional assays using in vitro tumorsphere formation.

RESULTS

A single administration of Cephaeline resulted in reduced viability of MEC cells along with the halt on tumor growth and cellular migration potential. Administration of Cephaeline resulted in chromatin histone acetylation as judged by the increased levels of H3K9ac and disruption of tumorspheres formation. Interestingly, ALDH levels were increased in UM-HMC-1 and UM-HMC-3A cell lines, while UM-HMC-2 showed a reduced enzymatic activity.

CONCLUSION

Cephaeline has shown anti-cancer properties in all MEC cell lines tested by regulating tumor cells' viability, migration, proliferation, and disrupting the ability of cancer cells to generate tumorspheres.

New tendencies in non-surgical periodontal therapy

The aim of this review was to update the evidence of new approaches to non-surgical therapy (NSPT) in the treatment of periodontitis. Preclinical and clinical studies addressing the benefits of adjunctive antimicrobial photodynamic therapy, probiotics, prebiotics/synbiotics, statins, pro-resolving mediators, omega-6 and -3, ozone, and epigenetic therapy were scrutinized and discussed. Currently, the outcomes of these nine new approaches, when compared with subgingival debridement alone, did not demonstrate a significant added clinical benefit. However, some of these new alternative interventions may have the potential to improve the outcomes of NSPT alone. Future evidence based on randomized controlled clinical trials would help clinicians and patients in the selection of different adjunctive therapies.

Epigenetic modulation of the tumor microenvironment in head and neck cancer: Challenges and opportunities

Head and neck cancer is globally challenging due to the resistance to therapy and aggressive behavior leading to high rates of mortality. Recent findings show that the tumor microenvironment plays a role in the maintenance and progression of many solid tumors, including head and neck cancer. The mechanisms involved in the modulation and regulation of the tumor microenvironment remain poorly understood. Increasing evidence suggests that epigenetic events can modulate the crosstalk between neoplastic and non-neoplastic cells during tumor progression. In this review, we explore the current understanding of the involvement of epigenetic events in the modulation of the tumor microenvironment and its impact on head and neck cancer behavior. We also explore the latest therapeutic strategies that use epigenetic-modulating drugs to manage tumor growth and progression.

Worldwide prevalence of PI3K-AKT-mTOR pathway mutations in head and neck cancer: A systematic review and meta-analysis

A systematic review (SR) and meta-analysis were conducted to determine the prevalence of PI3K-AKT-mTOR signaling pathway mutations in patients with head and neck cancer (HNC). Overall, 105 studies comprising 8630 patients and 1306 mutations were selected. The estimated mutations prevalence was 13 % for PIK3CA (95 % confidence interval [CI] = 11-14; I² = 82 %; p < 0.0001), 4% for PTEN (95 % CI = 3-5; I² = 55 %; p < 0.0001), 3% for MTOR (95 % CI = 2-4; I² = 5%; p = 0.40), and 2% for AKT (95 % CI = 1-2; I² = 50 %; p = 0.0001). We further stratified the available data of the participants according to risk factors and tumor characteristics, including HPV infection, tobacco use, alcohol exposure, TNM stage, and histological tumor differentiation, and performed subgroup analysis. We identified significant associations between PI3K-AKT-mTOR pathway-associated mutations and advanced TNM stage (odds ratio [OR] = 0.20; 95 % CI = 0.09-0.44; I² = 71 %; p = 0.0001) and oropharyngeal HPV-positive tumors and PIK3CA mutations (OR = 17.48; 95 % CI = 4.20-72.76; I² = 69 %; p < 0.0002). No associations were found between alcohol and tobacco exposure, and tumor differentiation grade. This SR demonstrated that the PI3K-AKT-mTOR pathway emerges as a potential prognostic factor and could offer a molecular basis for future studies on therapeutic targeting in HNC patients.

DNA methyltransferase expression is associated with cell proliferation in salivary mucoepidermoid carcinoma

OBJECTIVES

The present study investigated the correlation between the expression of DNA methyltransferase (DNMT)1, DNMT3A, and DNMT3B and the proliferation of mucoepidermoid carcinomas (MECs) using the molecular markers Ki-67 and cyclin D1. This study also demonstrates the effects of 5-aza-2-deoxycytidine (5AC) on the MEC tumor cell lines in relation to DNMT1 and DNMT3A expression, and cell-cycle arrest.

MATERIALS AND METHODS

The immunohistochemistry of DNMT1, DNMT3A, DNMT3B, Ki-67, and cyclin D1 was analyzed in 40 samples of MEC and 15 samples of healthy minor salivary glands. The effects of 5AC on DNMT1 and DNMT3B expression in MEC cell lines were analyzed by Western blot, and the effects of 5AC on the cell cycle were analyzed using flow cytometry.

RESULTS

The expression of DNMT1 and DNMT3B was more intense in MECs than in healthy salivary glands. A strong correlation was found between the expression of the DNMTs and the proliferation markers. This correlation was validated In Vitro, where treatment with 5AC reduced the expression of the DNMTs and the percentage of cells at the G2/M phase of the cell cycle.

CONCLUSION

The expression of DNMT1, DNMT3A, DNMT3B is correlated significantly with the expression of Ki-67 and cyclin D1. The treatment with 5AC reduces DNMT expression and decreases the percentage of cells at the G2/M phase of the cell cycle, while increasing the cells at the G0/G1 phase.

Association or Causation? Exploring the Oral Microbiome and Cancer Links

Several epidemiological investigations have found associations between poor oral health and different types of cancer, including colorectal, lung, pancreatic, and oral malignancies. The oral health parameters underlying these relationships include deficient oral hygiene, gingival bleeding, and bone and tooth loss. These parameters are related to periodontal diseases, which are directly and indirectly mediated by oral bacteria. Given the increased accessibility of microbial sequencing platforms, many recent studies have investigated the link between the oral microbiome and these cancers. Overall, it seems that oral dysbiotic states can contribute to tumorigenesis in the oral cavity as well as in distant body sites. Further, it appears that certain oral bacterial species can contribute to carcinogenesis, in particular, Fusobacterium nucleatum and Porphyromonas gingivalis, based on results from epidemiological as well as mechanistic studies. Yet, the strength of the findings from these investigations is hampered by the heterogeneity of the methods used to measure oral diseases, the treatment of confounding factors, the study design, the platforms employed for microbial analysis, and types of samples analyzed. Despite these limitations, there is an overall indication that the presence of oral dysbiosis that leads to oral diseases may directly and/or indirectly contribute to carcinogenesis. Proper methodological standardized approaches should be implemented in future epidemiological studies as well as in the mechanistic investigations carried out to explore these results.

Zirconia Implants and Marginal Bone Loss: A Systematic Review and Meta-Analysis of Clinical Studies

PURPOSE

The purpose of this study was to provide sufficient information on the clinical outcome of zirconia implants, mainly observing the survival rate and marginal bone loss (MBL), with a minimum follow-up of 12 months, to verify the adoption of ceramics as a rational possibility for dental implants.

MATERIALS AND METHODS

A systematic electronic search through the PubMed (MEDLINE) and EMBASE databases was performed by two independent reviewers to identify clinical studies published between January 2005 and April 2019 containing a minimum of 10 patients per study and 12 months of follow-up after functional loading. References from the selected articles were manually reviewed for further studies.

RESULTS

From the initial 1,225 articles retrieved, 19 met all the inclusion criteria. The marginal bone remodeling accounted for mean losses of 0.8 mm (95% CI: 0.60 to 1.00 mm) and 1.01 mm (95% CI: 0.72 to 1.29 mm) at 1 year and 2 years postloading, respectively. The failure rate of 6.8% was calculated for a mean follow-up period of 2.75 years, where the prevalence of early failure, late failure, and implant fracture was 3.4%, 1.7%, and 1.7%, respectively. The meta-analysis associated with the survival rate of one- and two-piece zirconia dental implants was hindered due to the lack of confidence interval or standard deviation information in most of the included articles.

CONCLUSION

Zirconia implants presented MBL values consistent with the standard in the global consensus, high survival rates, and considerable clinical results at short-term observation periods following prosthetic delivery.

Curcumin downregulates the PI3K-AKT-mTOR pathway and inhibits growth and progression in head and neck cancer cells

Curcumin, a polyphenol isolated from the rhizome of Curcuma longa, has been studied because of its antioxidant, antimicrobial, and antiinflammatory properties. This study aimed to evaluate the effects of curcumin on head and neck cancer (HNC) cell lines and how it modulates the PI3K-AKT-mTOR signaling pathway. Dose-response curves for curcumin were established for hypopharynx carcinoma (FaDu), tongue carcinoma (SCC-9), and keratinocytes (HaCaT) cell lines and IC₅₀ values were calculated. Cell cycle and cell death were investigated through flow cytometry. Cytoskeleton organization was assessed through phalloidin+FITC staining. qPCR array and western blot were performed to analyze gene and protein expression. Curcumin reduced cell viability in a dose-dependent and selective manner, induced cell death on SCC-9 cells (necrosis/late apoptosis: 44% curcumin vs. 16.4% vehicle), and arrested cell cycle at phase G₂ /M on SCC-9 and FaDu (G₂ : SCC-9-19.1% curcumin vs. 13.4% vehicle; FaDu-37.8% curcumin vs. 12.9% vehicle). Disorganized cytoskeleton and altered cell morphology were observed. Furthermore, curcumin downregulated the PI3K-AKT-mTOR signaling pathway by modifying the expression of key genes and proteins. These findings highlight the promising therapeutic potential of curcumin to inhibit HNC growth and progression and to modulate the PI3K-AKT-mTOR pathway.

Loss of PTEN sensitizes head and neck squamous cell carcinoma to 5-AZA-2'-deoxycytidine

OBJECTIVE

Head and neck squamous cell carcinoma (HNSCC) is an aggressive cancer associated with poor survival. Phosphatase and tensin homolog (PTEN) is a tumor suppressor gene involved in the maintenance of stem cells. DNA methylation is a known epigenetic modification involved in tumor progression. In this study, we investigated the effect of the DNA demethylation agent 5-AZA-2'-deoxycytidine (5-AZA) over HNSCC and its population of cancer stem cells (CSCs) presenting dysfunctional PTEN.

STUDY DESIGN

The effects of 5-AZA on HNSCC were evaluated by using WSU-HN13 cells. CSC was assessed by sphere-forming assays, along with the endogenous levels of aldehyde dehydrogenase. The clonogenic potential of tumors was evaluated, along with the protein expression of mTOR signaling and the identification of nuclear factor-κB (NF-κB) and epithelial-mesenchymal transition (EMT)-associated genes, using real-time polymerase chain reaction (PCR).

RESULTS

We observed that loss of PTEN enhances tumor biologic behavior, including colony- and tumor sphere-forming abilities. We also found that 5-AZA has an inhibitory effect over the CSCs and molecular markers associated with the NF-κB and EMT pathways.

CONCLUSIONS

Our findings suggest that the stratification of treatment of HNSCC based on PTEN status may identify a subset of patients who can benefit from the coadministration of 5-AZA.

The impact of photobiomodulation therapy on the biology and behavior of head and neck squamous cell carcinomas cell lines

Photobiomodulation therapy (PBMT) is an emerging therapeutic modality designed to prevent and treat chemotherapy-driven oral mucositis (OM). However, the response of tumor cells to the effects of PBMT remains poorly understood. Our study explores the effects of PBMT in head and neck squamous cell carcinoma (HNSCC) based on cellular proliferation, migration, and survival of tumor cells and its population of cancer stem cells (CSC). We explored the behavior of two HNSCC cell lines (HN6 and HN13) under two distinct conditions, a physiological growing condition (10% FBS), and under stress growing condition (2% FBS) prior to irradiation using diode laser (InGaAlP; MM Optics, São Carlos, SP, Brazil). Diode laser (660 nm) was applied with a power of 100 mW delivering a total energy per point of 0.24 J. MTT and wound healing test (scratch assay) were performed to evaluate, respectively, proliferation and migration of tumor cells. Clonogenic and spheres formation assays were also performed to evaluate the survival and percentage of CSC upon irradiation. Overall, we observed that PBMT does not exacerbate the behavior of HNSCC. We could only observe a decrease in cellular proliferation of one cell line (HN6) when cultured under nutritional stress conditions (p < .05). There were no significant differences between the control and the PBMT groups regarding cell migration, survival and the percentage of CSC. Collectively, our results suggest that in vitro administration of PBMT to HNSCC does not modify the behavior of tumor cells.

Immunotherapy improves efficacy and safety of patients with HPV positive and negative head and neck cancer: A systematic review and meta-analysis

BACKGROUND

Despite multiple modalities used to management of head and neck squamous cell carcinoma (HNSCC), disease control remains unsatisfactory. Immunotherapy is emerging as a novel therapeutic approach. This systematic review assesses clinical data regarding immunotherapy efficacy and safety.

METHODS

Data from 11 clinical trials testing immunotherapy in HNSCC were assessed. We performed the meta-analysis to correlate the overall survival (OS), response rate (RR), adverse effects, HPV status, and PD-L1 expression.

RESULTS

Immunotherapy extended OS (hazard ratio = 0.77, p < 0.0001) and RR significantly (risk ratio = 1.41, p = 0.02). Patients with HPV-positive HNSCC exhibited a better RR (risk ratio = 1.29, p = 0.24) and OS (11.5 vs. 6.3 months). PD-L1 positive tumors showed a higher OS (9.9 vs. 6.5 months). Moreover, immunotherapy caused less adverse effects than standard therapy.

CONCLUSION

Our results indicate the benefit of immunotherapy for improving RR and OS of HNSCC patients. The benefit is higher in patients with HPV and PD-L1 positive tumors.

Histones Acetylation and Cancer Stem Cells (CSCs)

Chromatin decondensation is a key mechanism that guarantees gene transcription and repair of the genome, regulated mainly by the acetylation of histones. Emerging evidence has pointed out to histones as a new controlling mechanism of stem cell maintenance and fate. In this chapter, we will focus on the methods used to enrich tumor cell lines for cancer stem cells, and in the methods to identify the status of the histone acetylation in cancer cells and stem cells using immunofluorescence, invasion, and adhesion assays and identification of nuclear size.

mTOR pathway protein immunoexpression as a prognostic factor for survival in head and neck cancer patients: a systematic review and meta-analysis

BACKGROUND

Several mTOR pathway proteins are involved in the regulation of cellular anabolism, growth, proliferation, and survival. Activated proteins in the mTOR pathway are deregulated in multiple types of cancers and could influence prognosis. However, it is unclear whether deregulation of mTOR pathway proteins serves a prognostic role in patients with head and neck cancer (HNC). Furthermore, proteins in the mTOR pathway may be important targets for anticancer therapy. The aim of this study was to summarize existing cohort studies to determine whether immunoexpression of mTOR pathway proteins are important prognostic factors for survival in patients with HNC.

MATERIALS AND METHODS

A systematic review was performed using the Cochrane, Lilacs, PubMed, ScienceDirect, Scopus, and Web of Science databases (up to 23 January 2015). A meta-analysis was conducted to measure the frequency of protein expression in head and neck cancer patient samples and the prognostic value of mTOR pathway proteins for overall survival (OS) and disease-free survival (DFS).

RESULTS

Twelve studies were included in our final analysis. The meta-analysis revealed that the frequency of overall expression of mTOR pathway proteins was 74.42% (CI: 63.3 to 84.0, P < 0.001, n = 2016 samples). The survival meta-analysis showed a pooled hazard ratio for OS and DFS of 1.44 (95% confidence interval [95% CI] 1.14-1.73) and 1.18 (95% CI 0.71-1.64), respectively.

CONCLUSION

This systematic review and meta-analysis support evidence that mTOR pathway proteins can be used as predictive markers for survival in patients with HNC because their expression was significantly associated with poor OS and short DFS.

Epigenetic Modifications of Histones in Periodontal Disease

Periodontitis is a chronic infectious disease driven by dysbiosis, an imbalance between commensal bacteria and the host organism. Periodontitis is a leading cause of tooth loss in adults and occurs in about 50% of the US population. In addition to the clinical challenges associated with treating periodontitis, the progression and chronic nature of this disease seriously affect human health. Emerging evidence suggests that periodontitis is associated with mechanisms beyond bacteria-induced protein and tissue degradation. Here, we hypothesize that bacteria are able to induce epigenetic modifications in oral epithelial cells mediated by histone modifications. In this study, we found that dysbiosis in vivo led to epigenetic modifications, including acetylation of histones and downregulation of DNA methyltransferase 1. In addition, in vitro exposure of oral epithelial cells to lipopolysaccharides resulted in histone modifications, activation of transcriptional coactivators, such as p300/CBP, and accumulation of nuclear factor-κB (NF-κB). Given that oral epithelial cells are the first line of defense for the periodontium against bacteria, we also evaluated whether activation of pathogen recognition receptors induced histone modifications. We found that activation of the Toll-like receptors 1, 2, and 4 and the nucleotide-binding oligomerization domain protein 1 induced histone acetylation in oral epithelial cells. Our findings corroborate the emerging concept that epigenetic modifications play a role in the development of periodontitis.

HPV Infection of the Head and Neck Region and Its Stem Cells

The human papillomavirus (HPV) is an etiologic agent associated with the development of head and neck squamous carcinoma (HNSCC)-in particular, oropharyngeal squamous cell carcinoma. The HPV-positive HNSCC is characterized by genetic alterations, clinical progression, and therapeutic response, which are distinct from HPV-negative head and neck cancers, suggesting that virus-associated tumors constitute a unique entity among head and neck cancers. Malignant stem cells, or cancer stem cells, are a subpopulation of tumor cells that self-renew, initiate new tumors upon transplantation, and are resistant to therapy, and their discovery has revealed novel effects of oncovirus infection in cancer. In this review, we provide a virus-centric view and novel insights into HPV-positive head and neck pathogenesis. We discuss the influence of cancer stem cells, HPV oncoproteins, altered molecular pathways, and mutations in cancer initiation and cancer progression. We compiled a catalogue of the mutations associated with HPV-positive HNSCC, which may be a useful resource for genomic-based studies aiming to develop personalized therapies. We also explain recent changes in mass vaccination campaigns against HPV and the potential long-term impact of vaccinations on the prevention and treatment of HPV-positive head and neck cancers.

Keratoacanthoma of the Lip: Activation of the mTOR Pathway, Tumor Suppressor Proteins, and Tumor Senescence

The PI3K-PTEN-mTOR is one of the most important pathways involved in cancer development and progression; however, its role in keratoacanthoma (KA) is poorly understood. In this study, we investigated the activation of key proteins in the PI3K-mTOR pathway in lip KA. We analyzed the activation of the PI3K-PTEN-mTOR pathway using human tumor samples stained for well-established protein markers in this pathway, including pS6 and pAKT phosphoproteins. We assessed proliferation using Ki-67 and performed additional morphological and immunohistochemical analysis using anti-PTEN and anti-p16 antibodies.We found that the majority of KA labeled to pS6 and not pAKT. PTEN expression was inversely correlated with Ki-67 expression. In addition to PTEN expression, KA cells were positive for p16 senescence marker. PI3K-PTEN-mTOR pathway is activated in lip KA, leading to downstream activation of mTORC1, but not mTORC2. This pathway plays an important role in KA progression by promoting proliferation and activation of oncogenic-induced senescence.

Immunoprofile of c-MET/PI3K signaling in human salivary gland tumors

OBJECTIVE

The aim of this study was to analyze the expression pattern of proteins in the HGF/c-MET/PI3K signaling pathway in salivary gland tumors (SGTs) and to correlate the findings with the proliferative index and clinical parameters.

STUDY DESIGN

We assembled tissue microarrays (TMAs) of 108 cases of SGTs, including 69 cases of pleomorphic adenoma (PA), 24 cases of adenoid cystic carcinoma (AdCC), and 15 cases of mucoepidermoid carcinoma (MEC). An immunohistochemical analysis of hepatocyte growth factor (HGF), MET phosphorylation (p-MET), protein kinase B (AKT) phosphorylation (p-AKT), and Ki-67 proteins was performed.

RESULTS

Benign and malignant SGTs presented similar scores of HGF-positive cells (P = .36), whereas, malignant SGTs exhibited higher levels of p-MET (P = .001) and p-AKT (P = .001) than benign SGTs. No correlation of HGF, p-MET, or p-AKT expression was observed with clinical parameters. PA had a lower proliferative index than either AdCC (P = .001) or MEC (P = .001).

CONCLUSIONS

The salivary gland carcinomas exhibited increased activation of the HGF pathway, as evidenced by the phosphorylation of the MET receptor, and increased activation of the PI3K pathway, as indicated by p-AKT. These data suggest that the HGF/c-MET/PI3K signaling pathway is active in SGTs, especially in malignant neoplasms.

Laser phototherapy triggers the production of reactive oxygen species in oral epithelial cells without inducing DNA damage

Laser phototherapy (LPT) is widely used in clinical practice to accelerate healing. Although the use of LPT has advantages, the molecular mechanisms involved in the process of accelerated healing and the safety concerns associated with LPT are still poorly understood. We investigated the physiological effects of LPT irradiation on the production and accumulation of reactive oxygen species (ROS), genomic instability, and deoxyribose nucleic acid (DNA) damage in human epithelial cells. In contrast to a high energy density (20  J/cm²), laser administered at a low energy density (4  J/cm²) resulted in the accumulation of ROS. Interestingly, 4  J/cm² of LPT did not induce DNA damage, genomic instability, or nuclear influx of the BRCA1 DNA damage repair protein, a known genome protective molecule that actively participates in DNA repair. Our results suggest that administration of low energy densities of LPT induces the accumulation of safe levels of ROS, which may explain the accelerated healing results observed in patients. These findings indicate that epithelial cells have an endowed molecular circuitry that responds to LPT by physiologically inducing accumulation of ROS, which triggers accelerated healing. Importantly, our results suggest that low energy densities of LPT can serve as a safe therapy to accelerate epithelial healing.

Cyclin D1-induced proliferation is independent of beta-catenin in head and neck cancer

OBJECTIVE

Head and neck squamous cell carcinoma (HNSCC) progression and metastasis have previously been associated with the activation of phosphatidylinositol 3-kinase-protein kinase B (PI3K-Akt) and Wnt signalling pathways, which lead to the activation of pro-proliferative genes, such as cyclin D1. The current study aims to investigate whether there is a crosstalk between these pathways in HNSCC and which pathway is more likely to regulate cyclin D1.

MATERIAL AND METHODS

Two HNSCC and a control keratinocyte cell lines were treated with EGF and wortmannin to respectively activate and block the PI3K-Akt and Wnt pathways. Partial and total levels of cyclin D1, beta-catenin and Akt were evaluated by Western blotting and immunofluorescence. Twenty-four paraffin-embedded samples of human HNSCC, as well as normal oral mucosa biopsies, were also immunohistochemically evaluated for beta-catenin and cyclin D1 expression.

RESULTS

Following both treatments, change in cyclin D1 protein was correlated with Akt levels only. Cytoplasmic staining for beta-catenin and loss of its membranous expression in the HNSCC invasive areas were found in 92% of the HNSCC biopsies.

CONCLUSION

Taken together, we show that the change in cyclin D1 levels is more likely to be due to the EGFR-Akt pathway activation than due to beta-catenin nuclear translocation.

Exploiting PI3K/mTOR signaling to accelerate epithelial wound healing

The molecular circuitries controlling the process of skin wound healing have gained new significant insights in recent years. This knowledge is built on landmark studies on skin embryogenesis, maturation, and differentiation. Furthermore, the identification, characterization, and elucidation of the biological roles of adult skin epithelial stem cells and their influence in tissue homeostasis have provided the foundation for the overall understanding of the process of skin wound healing and tissue repair. Among numerous signaling pathways associated with epithelial functions, the PI3K/Akt/mTOR signaling route has gained substantial attention with the generation of animal models capable of dissecting individual components of the pathway, thereby providing a novel insight into the molecular framework underlying skin homeostasis and tissue regeneration. In this review, we focus on recent findings regarding the mechanisms involved in wound healing associated with the upregulation of the activity of the PI3K/Akt/mTOR circuitry. This review highlights critical findings on the molecular mechanisms controlling the activation of mTOR, a downstream component of the PI3K-PTEN pathway, which is directly involved in epithelial migration and proliferation. We discuss how this emerging information can be exploited for the development of novel pharmacological intervention strategies to accelerate the healing of critical size wounds.

Requirement of Rac1 distinguishes follicular from interfollicular epithelial stem cells

Epithelial stem cells in the bulge region within the hair follicle maintain the cyclic hair growth, but whether these stem cells also contribute to the epidermal renewal remains unclear. Here, we observed that the conditional deletion of the Rac1 gene in the mouse skin, including the potential follicular and epidermal stem cell compartments, results in alopecia owing to defective hair development. Surprisingly, mice lacking the expression of this Rho GTPase do not display major alterations in the interfollicular skin. Furthermore, Rac1 excision from primary epithelial keratinocytes results in the inability to reconstitute hair follicles and sebaceous glands when grafted onto mice, but epithelial cells lacking Rac1 can nonetheless form a healthy epidermis. Together, these findings support the emerging view that the epidermis and the hair follicles are maintained by different epithelial stem cells, and provide evidence that the requirement for Rac1 function can distinguish these distinct stem cells populations.

Osteolipoma: a rare lesion in the oral cavity

We present the case of a 65-year-old woman who had a painless mass in the left buccal mucosa. Histology showed a benign osteolipoma.

[Proposal for a procedure for the detection of ophthalmic disorders in school children]

The proposal for a visual acuity test (A.V.) arose from a survey conducted among School Children of the "Ciclo Básico (C.B.)" i.é., the first two years of Elementary School in S. Carlos, S. Paulo State, Brazil. Nine schools participated in this study. The teachers were properly trained to apply the A. V. and squinting tests according to a standardized procedure. Of 2,025 children tested, 88.1% showed levels of A. V. higher than 0.8, and a squinting prevalence of 2.17%. When the application of the test was over, each school presented its proposals for the systematical application of such tests. These proposals had a common point: the test should be applied by the teachers themselves under the supervision of the coordinators of the C. B. The school nurse would be responsible for giving overall assistance to all the activities of the program at all levels.