The role of hypoxia in oral cancer and potentially malignant disorders: a review

Induction of Peroxiredoxin 1 by Hypoxia Promotes Cellular Autophagy and Cell Proliferation in Oral Leukoplakia via HIF-1α/BNIP3 Pathway

Hypoxia is a key trigger in the transformation of oral leukoplakia into oral cancer. However, it is still too early to determine the role of hypoxia in the development of oral leukoplakia. Prx1, an antioxidant protein, upregulated by hypoxia, regulates cellular autophagy in leukoplakia. This study aimed to understand the mechanisms by which hypoxia induces Prx1 expression during autophagy in oral leukoplakia. We used an experimental model of tongue epithelial hyperplasia induced by 4-nitroquinoline-1-oxide (4NQO) and dysplastic oral keratinocytes. Prx1 knockdown DOK cells, Leuk-1 cells and control cells were harvested, and cell proliferation was assayed using the Cell Counting Kit-8. Several hypoxia and autophagy-related proteins were examined using quantitative real-time polymerase chain reaction, immunohistochemistry, immunofluorescence, and western blotting in cells and mouse tongue tissues. In addition, the ultrastructure of the cells was observed by transmission electron microscopy. Hypoxia induces cell proliferation, autophagic vesicles and the expression of Prx1, BNIP3, LC3II/I and Beclin-1 in DOK and Leuk-1 cells. However, these effects were all attenuated by Prx1 knockdown. Histologically, 4NQO induced epithelial hyperplasia in the tongue mucosa. The expression of proliferation marker PCNA, autophagy-related proteins LC3B and Beclin-1, as well as HIF-1α/BNIP3 was significantly lower in the tongue tissues of Prx1flox/flox:Cre+ mice compared with Prx1flox/flox mice. In Prx1flox/flox:Cre+ mice, an increased expression of HIF-1α/BNIP3, LC3B and Beclin-1 was detected in epithelial hyperplasia tongue tissues compared to normal tissues. The current study suggests that Prx1 may promotes cell proliferation and autophagy in oral leukoplakia cells via the HIF-1α/BNIP3 pathway.

Areca nut and oral cancer

INTRODUCTION

The association between areca nut consumption and oral cancer has been a subject of increasing concern in global public health.

GLOBAL PERSPECTIVE

Areca nut, often chewed in various forms such as betel quid, is deeply rooted in cultural practices across Asia and other parts of the world. Epidemiological studies consistently reveal a significant correlation between areca nut use and the incidence of oral cancer, emphasizing the need for targeted preventive measures. The complex interplay of areca nut's bioactive compounds, particularly arecoline, with cellular processes, contributes to the initiation and progression of oral carcinogenesis. Mechanistic insights into the genotoxic and cytotoxic effects of its components underscore the urgency for comprehensive public health interventions.

PUBLIC HEALTH

Efforts to address this public health challenge involve multidisciplinary approaches, encompassing education, policy implementation, and behavioral interventions. Understanding the socio-cultural factors influencing areca nut consumption is pivotal for designing effective awareness campaigns and cessation programs.

CONCLUSION

As oral cancer remains a significant global health burden, unraveling the nuanced relationship between areca nut and its role in oral carcinogenesis is crucial for advancing preventive strategies and mitigating the impact of this modifiable risk factor.

Expression of HIF-1α and Nestin in oral squamous cell carcinoma and its association with vasculogenic mimicry

AIM

To evaluate and correlate the expression of HIF1-α and Nestin in tumor center and periphery of nonmetastatic, and recurrent oral squamous cell carcinoma (OSCC) and its association with vasculogenic mimicry.

MATERIALS AND METHODS

About 60 histopathological proven cases of OSCC with proper tumor center and periphery were collected. Among them 25 are nonmetastatic, 25 metastatic, and 10 recurrent cases of OSCC. Immunohistochemical analysis of HIF, Nestin, and CD31/PAS (periodic acid Schiff) was done.

RESULTS

Based on the extent of tumor cells stained, staining intensity and index score, expression of both HIF and Nestin was highly significant in periphery of metastatic OSCC with a P value of 0.003* and 0.001*. The total number of vessels expressed in nonmetastatic, metastatic, and recurrent OSCC was not significant but the overall expression of CD31/PAS was significant in the periphery of the tumor with a P value of 0.024*. Correlating the overall expression, HIF showed a positive relation with Nestin and CD31/PAS with a P value of 0.026* and 0.038* in nonmetastatic OSCC using Pearson's correlation coefficient analysis.

CONCLUSION

Based on the above results hypoxia plays a vital role in cancer stem cells maintenance with the formation of vessel-like structures by tumor cells at an early stage of cancer development.

Microbial Changes Associated With Oral Cavity Cancer Progression

OBJECTIVE

To examine the oral microbiome in the context of oral cavity squamous cell carcinoma.

STUDY DESIGN

Basic science research.

SETTING

Academic medical center.

METHODS

Oral swabs were collected from patients presenting to the operating room for management of oral cavity squamous cell carcinoma and from age- and sex-matched control patients receiving surgery for unrelated benign conditions. 16S ribosomal RNA (rRNA) sequencing was performed on genetic material obtained from swabs. A bacterial rRNA gene library was created and sequence reads were sorted into taxonomic units.

RESULTS

Thirty-one control patients (17 males) and 35 cancer patients (21 males) were enrolled. Ages ranged from 23 to 89 (median 63) for control patients and 35 to 86 (median 66) for cancer patients. Sixty-one percent of control patients and 63% of cancer patients were smokers. 16S analyses demonstrated a significant decrease in Streptococcus genera in oral cancer patients (34.11% vs 21.74% of the population, p = .04). Increases in Fusobacterium, Peptostreptococcus, Parvimonas, and Neisseria were also found. The abundance of these bacteria correlated with tumor T-stage.

CONCLUSION

16S rRNA sequencing demonstrated changes in bacterial populations in oral cavity cancer and its progression compared to noncancer controls. We found increases in bacteria genera that correspond with tumor stage-Fusobacteria, Peptostreptococcus, Parvimonas, Neisseria, and Treponema. These data suggest that oral cancer creates an environment to facilitate foreign bacterial growth, rather than implicating a specific bacterial species in carcinogenesis. These bacteria can be employed as a potential marker for tumor progression or interrogated to better characterize the tumor microenvironment.

Near-infrared rhodol dyes bearing salicylaldehyde moieties for ratiometric pH sensing in live cells during mitophagy and under hypoxia conditions

We describe a simple but efficient approach to make fluorescent probes A and B based on rhodol dyes incorporated with salicyaldehyde moiety for monitoring pH changes in mitochondria under oxidative stresses and hypoxia conditions, and for tracking mitophagy processes. Probes A and B possess pKa values (pKa ≈ 6.41 and 6.83 respectively) near physiological pH and exhibit decent mitochondria-targeted capabilities, low cytotoxicity, and useful ratiometric and reversible pH responses, which make the probes appropriate for monitoring pH fluctuations of mitochondria in living cells with built-in calibration feature for quantitative analysis. The probes have been effectively useful for the ratiometric determination of pH variations of mitochondria under the stimuli of carbonyl cyanide-4(trifluoromethoxy)phenylhydrazone (FCCP), hydrogen peroxide (H2O2), and N-acetyl cysteine (NAC), and during mitophagy triggered by cell nutrient deprivation, and under hypoxia conditions with cobalt chloride (CoCl2) treatment in living cells. In addition, probe A was efficient in visualizing pH changes in the larvae of fruit flies.

Carcinogenic Effects of Areca Nut and Its Metabolites: A Review of the Experimental Evidence

Oral cancers (OC) are among the most frequent malignancies encountered in Southeast Asia, primarily due to the prevalent habit of betel quid (BQ) and smokeless tobacco use in this region. Areca nut (AN), the primary ingredient in BQ, contains several alkaloids, including arecoline, arecaidine, guvacoline, and guvacine. These have been associated with both the AN abuse liability and carcinogenicity. Additionally, variations in AN alkaloid levels could lead to differences in the addictiveness and carcinogenic potential across various AN-containing products. Recent studies based on animal models and in vitro experiments show cellular and molecular effects induced by AN. These comprise promoting epithelial-mesenchymal transition, autophagy initiation, tissue hypoxia, genotoxicity, cytotoxicity, and cell death. Further, clinical research endorses these undesired harmful effects in humans. Oral submucosal fibrosis, a potentially malignant disease of the oral cavity, is predominantly reported from the geographical areas of the globe where AN is habitually chewed. OC in chronic AN users presents a more aggressive phenotype, such as resistance to anti-cancer drugs. The available evidence on the carcinogenicity of AN based on the findings reported in the recently published experimental studies is discussed in the present review.

A Novel Preclinical In Vitro 3D Model of Oral Carcinogenesis for Biomarker Discovery and Drug Testing

This study aimed to develop an in vitro three-dimensional (3D) cell culture model of oral carcinogenesis for the rapid, scalable testing of chemotherapeutic agents. Spheroids of normal (HOK) and dysplastic (DOK) human oral keratinocytes were cultured and treated with 4-nitroquinoline-1-oxide (4NQO). A 3D invasion assay using Matrigel was performed to validate the model. RNA was extracted and subjected to transcriptomic analysis to validate the model and assess carcinogen-induced changes. The VEGF inhibitors pazopanib and lenvatinib were tested in the model and were validated by a 3D invasion assay, which demonstrated that changes induced by the carcinogen in spheroids were consistent with a malignant phenotype. Further validation was obtained by bioinformatic analyses, which showed the enrichment of pathways associated with hallmarks of cancer and VEGF signalling. Overexpression of common genes associated with tobacco-induced oral squamous cell carcinoma (OSCC), such as MMP1, MMP3, MMP9, YAP1, CYP1A1, and CYP1B1, was also observed. Pazopanib and lenvatinib inhibited the invasion of transformed spheroids. In summary, we successfully established a 3D spheroid model of oral carcinogenesis for biomarker discovery and drug testing. This model is a validated preclinical model for OSCC development and would be suitable for testing a range of chemotherapeutic agents.

Immunoexpression profile of hypoxia-inducible factor (HIF) targets in potentially malignant and malignant oral lesions: a pilot study

Oral potentially malignant disorders (OPMD) are associated with an increased risk of oral squamous cell carcinoma (OSCC). OSCC has an aggressive profile and is the most prevalent among different head and neck malignancies. Most OSCC patients are diagnosed with advanced stage tumors and have a poor prognosis. Cancer cells are able to reprogram their metabolism, even in the presence of oxygen, enhancing the conversion of glucose to lactate via the glycolytic pathway, a phenomenon mainly regulated by hypoxia-inducible factor (HIF) signaling. Thus, several glycometabolism-related biomarkers are upregulated. This study aimed to evaluate the immunoexpression of the HIF targets GLUT1, GLUT3, HK2, PFKL, PKM2, pPDH, LDHA, MCT4, and CAIX in OPMD and OSCC samples, in order to identify potential correlations between biomarkers' immunoexpression, clinicopathological features, and prognostic parameters. OSCC and OPMD samples from 21 and 34 patients (respectively) were retrospectively collected and stained for the different biomarkers by immunohistochemistry. CAIX and MCT4 expressions were significantly higher in OSCC samples when compared with OPMD samples, while the rest were also expressed by OPMD. GLUT3 and PKM2 alone, and the concomitant expression of more than four glycometabolism-related biomarkers were significantly correlated with the presence of dysplasia in OPMD. When considering OSCC cases, a trend toward increased expression of biomarkers and poor clinicopathological features was observed, and the differences regarding HK2, PFKL, LDHA and MCT4 expression were significant. Moreover, HK2 and CAIX were correlated with low survival rates. GLUT1 and GLUT3 were significantly associated with poor outcome when their expression was observed in the hypoxic region of malignant lesions. OPMD and OSCC cells overexpress glycolysis-related proteins, which is associated with aggressive features and poor patient outcome. Further research is needed to deeply understand the glycolic phenotype in the process of oral carcinogenesis.

Construction and verification of a hypoxia-related nine-gene prognostic model in uveal melanoma based on integrated single-cell and bulk RNA sequencing analyses

Uveal melanoma (UM) is the most common primary intraocular tumor with high metastasis and poor prognosis among adults. Hypoxia participates in the metastasis process in various types of cancers. It is reported that the increased expression of hypoxia inducible factor 1 alpha subunit (HIF1A), a hypoxia-related molecule, is associated with worse prognoses of UM patients. Based on the integrated analysis of single-cell sequencing (scRNA-seq) dataset from Gene Expression Omnibus (GEO) and bulk RNA-seq dataset from the Cancer Genome Atlas (TCGA), we found hypoxia was the key feature in UM progression and identified 47 common hypoxia-related differentially expressed genes (DEGs) for the following research. Univariate cox analysis and LASSO-Cox regression analysis were performed to establish a nine-gene prognostic model. According to this model, UM patients could be divided into high- and low-risk groups, with a significant difference in overall survival and progression free survival between the two groups (P < 0.001). The accuracy of the predictive model was also verified on two other independent datasets. In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses revealed that these hypoxia-related DEGs were enriched in immune and cancer related pathways. The proportion of immune infiltration and the expression of immune biomarkers were different between high- and low-risk UM patients, providing potential targets for UM immunotherapy. Hence, our hypoxia-related nine-gene model could efficiently predict the prognosis and guide personalized therapies for UM patients.

Microenvironment in Oral Potentially Malignant Disorders: Multi-Dimensional Characteristics and Mechanisms of Carcinogenesis

Oral potentially malignant disorders (OPMDs) are a group of diseases involving the oral mucosa and that have a risk of carcinogenesis. The microenvironment is closely related to carcinogenesis and cancer progression by regulating the immune response, cell metabolic activities, and mechanical characteristics. Meanwhile, there are extensive interactions between the microenvironments that remodel and provide favorable conditions for cancer initiation. However, the changes, exact roles, and interactions of microenvironments during the carcinogenesis of OPMDs have not been fully elucidated. Here, we present an updated landscape of the microenvironments in OPMDs, emphasizing the changes in the immune microenvironment, metabolic microenvironment, mechanical microenvironment, and neural microenvironment during carcinogenesis and their carcinogenic mechanisms. We then propose an immuno–metabolic–mechanical–neural interaction network to describe their close relationships. Lastly, we summarize the therapeutic strategies for targeting microenvironments, and provide an outlook on future research directions and clinical applications. This review depicts a vivid microenvironment landscape and sheds light on new strategies to prevent the carcinogenesis of OPMDs.

Impact of hyperglycemia on the expression of GLUT1 during oral carcinogenesis in rats

BACKGROUND

On the background of the epidemiological link between diabetes and oral cancer, the present study aimed to analyze the potential involvement of selected glucose transporters (GLUT1/GLUT3/GLUT4), if any, in such putative association.

METHODS AND RESULTS

Oral carcinogenesis was induced by 4-nitroquinoline N-oxide in 10 non-diabetic and 10 diabetic rats; 8 non-diabetic and 7 diabetic rats served as controls. Expressions of selected GLUTs at mRNA and protein levels were analyzed in oral tissue (normal/lesion) by quantitative real-time PCR and immunohistochemistry respectively. Premalignant lesions (hyperplasia/dysplasia/carcinoma-in-situ) appeared on tongues of carcinogen-treated animals. Significant increase of GLUT1mRNA level was seen from normal to lesion tongues, along increasing lesion grades (from hyperplasia/mild dysplasia to moderate/severe dysplasia) and in lesions induced under hyperglycemic condition than that induced under normoglycemic one; a similar trend was found in transcript variant-1 of GLUT1, but not in variant-2. GLUT3 and GLUT4 mRNA levels were comparable among lesions irrespective of grades and glycemic status. Concordant to mRNA level, overall expression of GLUT1 protein was higher in tongue lesions in presence of hyperglycemia than in absence of such condition; non-lesion portions of tongues exposed to carcinogen showed a similar trend. Moreover in carcinogen-treated groups, non-lesion and lesion portions of tongues under hyperglycemic condition showed predominantly membranous expression for GLUT1 which was again significantly higher than equivalent portions of tongue under normoglycemic condition.

CONCLUSION

Hyperglycemia seemed to favor GLUT1 over-expression and membrane localization of the protein during oral carcinogenesis. GLUT1 transcript variant-1 appeared to be more important than variant-2 in disease pathogenesis.

Rhodol-derived turn-on fluorescent chemosensor for ultrasensitive detection of nitroreductase activity in bacteria and bioimaging in oral cancer cells

The detection of intracellular nitroreductase (NTR) activity is important for the study of hypoxia in organisms. In the present study, a Rhodol-derived fluorescent chemosensor (Rhod-NO₂) was synthesized in a one-step procedure. Rhod-NO₂ exhibits 110-fold fluorescence enhancement in the presence of NTR. Moreover, Rhod-NO₂ demonstrates high NTR selectivity and sensitivity (LOD, 0.6 ng/mL). The mode of Rhod-NO₂ binding to NTR was also revealed by molecular docking. In addition, the reaction and luminescence mechanisms were evaluated by MS and TDDFT theoretical calculations, respectively. Finally, Rhod-NO₂ was successfully applied to monitor NTR production during Escherichia coli (E. coli) growth, and to visually analyze NTR production in malignant oral cancer cells under hypoxia. Thus, Rhod-NO₂ represents a new molecular tool to further understanding of the biological function of NTR.

Biological implications of the immune factors in the tumour microenvironment of oral cancer

OBJECTIVE

The objective of this review is to decipher the biological implications of the immune factors in the tumour microenvironment in oral cancer. The restoration of balance between tumour tolerance and tumour eradication by the host immune cells is critical to provide effective therapeutic strategies.

DESIGN

The specific role of the stromal and the immune components in oral cancer was reviewed with a tailored search strategy using relevant keywords. The articles were retrieved from bibliometric databases indexed in PubMed, Scopus, and Embase. An in silico analysis was performed to identify potential drug candidates for immunotherapy, by accessing the Drug-Gene Interactions Database (DGIdb) using the rDGIdb package.

RESULTS

There is compelling evidence for the role of the cellular and extracellular components of the tumour microenvironment in inducing immunosuppression and progression of oral cancer. The druggable candidates specifically targeting the immune system are a viable option in the treatment of oral cancer as they can regulate the tumour microenvironment.

CONCLUSION

A complex interaction between the tumour and the immunological microenvironment influences the disease outcome in oral cancer. Targeting specific components of the immune system might be relevant, as immunotherapy may become the new standard of care for oral cancer.

Hypoxia-induced ROS promotes mitochondrial fission and cisplatin chemosensitivity via HIF-1α/Mff regulation in head and neck squamous cell carcinoma

PURPOSE

Chemotherapy based on cisplatin (CDDP) has been established as the treatment of choice for head and neck squamous cell carcinoma (HNSCC). Malignant tumors respond to microenvironmental alterations through a dynamic balance between mitochondrial fission and fusion. HNSCCs are known to exhibit hypoxic conditions, yet the respective effects and underlying mechanisms of hypoxia on chemosensitivity and mitochondrial dynamics remain to be resolved.

METHODS

The effect of hypoxia on the chemosensitivity of HNCC cells was determined by flow cytometry. Mitochondrial fission factor (Mff) expression was assessed by RT-PCR and Western blotting in hypoxic HNSCC cells, and further verified in primary CDDP-sensitive and CDDP-resistant HSNCC samples. The biological function of Mff was evaluated by loss of function and gain of function analyses, both in vitro and in vivo.

RESULTS

We found that hypoxia promoted mitochondrial fission and CDDP sensitivity in HNSCC cells. Importantly, Mff was found to be correlated with chemosensitivity in primary clinical samples under hypoxic conditions. Hypoxia-inducible factor 1α (HIF-1α) was found to markedly increase Mff transcription and to directly bind to Mff. Hypoxia enhanced the release of reactive oxygen species (ROS) and upregulated the expression of Mff via HIF-1α in HNSCC cells. ROS depletion in HNSCC cells attenuated HIF-1α expression, Mff expression and mitochondrial fission. Moreover, Mff knockdown led to suppression of hypoxia-induced mitochondrial fission and to decreased CDDP chemosensitivity in vivo and in vitro.

CONCLUSIONS

Our findings indicate that hypoxia-induced release of ROS can promote mitochondrial fission and CDDP chemosensitivity via HIF1α/Mff regulation in HNSCC cells, indicating that Mff may serve as a biomarker to predict neoadjuvant chemosensitivity in HNSCC patients and as a target for overcoming chemoresistance.

Intersecting Mechanisms of Hypoxia and Prostaglandin E2-Mediated Inflammation in the Comparative Biology of Oral Squamous Cell Carcinoma

The importance of inflammation in the pathogenesis of cancer was first proposed by Rudolph Virchow over 150 years ago, and our understanding of its significance has grown over decades of biomedical research. The arachidonic acid pathway of inflammation, including cyclooxygenase (COX) enzymes, PGE2 synthase enzymes, prostaglandin E2 (PGE2) and PGE2 receptors has been extensively studied and has been associated with different diseases and different types of cancers, including oral squamous cell carcinoma (OSCC). In addition to inflammation in the tumour microenvironment, low oxygen levels (hypoxia) within tumours have also been shown to contribute to tumour progression. Understandably, most of our OSCC knowledge comes from study of this aggressive cancer in human patients and in experimental rodent models. However, domestic animals develop OSCC spontaneously and this is an important, and difficult to treat, form of cancer in veterinary medicine. The primary goal of this review article is to explore the available evidence regarding interaction between hypoxia and the arachidonic acid pathway of inflammation during malignant behaviour of OSCC. Overlapping mechanisms in hypoxia and inflammation can contribute to tumour growth, angiogenesis, and, importantly, resistance to therapy. The benefits and controversies of anti-inflammatory and anti-angiogenic therapies for human and animal OSCC patients will be discussed, including conventional pharmaceutical agents as well as natural products.

Conspicuous and frank dilated vascular spaces: A marker of malignant transformation in oral submucous fibrosis

Histo-morphological alterations observed at mucosal surgical margins can be envisaged as potential markers of malignant transformation. In this paper, we have presented a very striking observation at the mucosal surgical margins of oral squamous cell carcinoma arising in the background of oral submucous fibrosis (OSCC-OSMF). Out of 38 cases of OSCC-OSMF, 22 (57.89%) showed conspicuous large dilated vascular spaces lined by endothelial cells in the background of dense fibrosis. These large dilated areas were engorged with red blood cells and were located at the juxta-epithelial and submucosal regions. Since surgical margin tissues are biologically close to malignant transformation, we proposed this unique feature as a potential predictive marker for oral submucous fibrosis that will aid in the early detection of OSCC. Future cohort studies are warranted to prove the authenticity of the present observations.

Rational Design of High-Relaxivity EuII -Based Contrast Agents for Magnetic Resonance Imaging of Low-Oxygen Environments

Metal-based contrast agents for magnetic resonance imaging present a promising avenue to image hypoxia. EuII -based contrast agents have a unique biologically relevant redox couple, EuII/III , that distinguishes this metal for use in hypoxia imaging. To that end, we investigated a strategy to enhance the contrast-enhancing capabilities of EuII -based cryptates in magnetic resonance imaging by controlling the rotational dynamics. Two dimetallic, EuII -containing cryptates were synthesized to test the efficacy of rigid versus flexible coupling strategies. A flexible strategy to dimerization led to a modest (114 %) increase in contrast enhancement per Eu ion (60 MHz, 298 K), but a rigid linking strategy led to an excellent (186 %) increase in contrast enhancement despite this compound's having the smaller molecular mass of the two dimetallic complexes. We envision the rigid linking strategy to be useful in the future design of potent EuII -based contrast agents for magnetic resonance imaging.

Notch in Head and Neck Cancer

Head and neck cancer is a group of neoplastic diseases affecting the facial, oral, and neck region. It is one of the most common cancers worldwide with an aggressive, invasive evolution. Due to the heterogeneity of the tissues affected, it is particularly challenging to study the molecular mechanisms at the basis of these tumors, and to date we are still lacking accurate targets for prevention and therapy. The Notch signaling is involved in a variety of tumorigenic mechanisms, such as regulation of the tumor microenvironment, aberrant intercellular communication, and altered metabolism. Here, we provide an up-to-date review of the role of Notch in head and neck cancer and draw parallels with other types of solid tumors where the Notch pathway plays a crucial role in emergence, maintenance, and progression of the disease. We therefore give a perspective view on the importance of the pathway in neoplastic development in order to define future lines of research and novel therapeutic approaches.

Gene and immunohistochemical expression of HIF-1α, GLUT-1, FASN, and adipophilin in carcinoma ex pleomorphic adenoma development

OBJECTIVE

To analyze the gene and immunohistochemical expression of HIF-1α, GLUT-1, FASN, and adipophilin in normal salivary gland (NSG), pleomorphic adenoma (PA), and carcinoma ex pleomorphic adenoma (CXPA) samples.

MATERIAL AND METHODS

The gene expression was investigated by the real-time PCR (qRT-PCR) method in 9 samples of frozen tissues of normal salivary gland, 13 PA, and 10 CXPA. We validated the reactions by immunohistochemistry on 20 samples from NSG, 85 PA, and 44 CXPA.

RESULTS

Our results showed that there was no statistically significant difference in HIF-1α gene and immunohistochemistry expression among the tissues studied while FASN gene and immunohistochemistry expression increased along the carcinogenesis of the PA. GLUT-1 was significantly more expressed in tumor tissues (PA and CXPA), although protein is mainly expressed in transformed cells than in PA and NSG. In contrast, adipophilin was significantly more expressed in NSG while the expression of the protein increased in PA and CXPA.

CONCLUSIONS

In summary, the data presented here suggest that neoplastic cells reprogram the expression of GLUT-1 and adipophilin to adapt to the tumor microenvironment and reinforce, through immunohistochemical results, a possible transcriptional and post-translational regulatory mechanisms that act on the expression of these genes.

Propofol suppresses hypoxia-induced esophageal cancer cell migration, invasion, and EMT through regulating lncRNA TMPO-AS1/miR-498 axis

Background

Propofol has been reported to be related to the migration, invasion, and epithelial‐mesenchymal transition (EMT) of esophageal cancer (EC) cells. However, the detailed mechanism has not yet been fully reported. The purpose of this research was to elucidate the function of long non‐coding RNA TMPO antisense RNA 1 (lncRNA TMPO‐AS1) and microRNA‐498 (miR‐498) in propofol‐regulated EC.

Methods

Transwell assay was performed to assess cell migratory and invasive abilities. Western blot assay was employed to determine the levels of EMT markers and hypoxia inducible factor‐1 (HIF‐1α). Quantitative real‐time polymerase chain reaction (qRT‐PCR) was carried out to detect the levels of TMPO‐AS1 and miR‐498. Moreover, the interaction between TMPO‐AS1 and miR‐498 was predicted by starBase, and then confirmed by the dual‐luciferase reporter assay and RNA immunoprecipitation (RIP) assay.

Results

Propofol suppressed hypoxia‐induced EC cell migration, invasion, and EMT. Both TMPO‐AS1 overexpression and miR‐498 knockdown weakened the effect of propofol on hypoxia‐induced EC cell progression. Interestingly, TMPO‐AS1 targeted miR‐498 and suppressed miR‐498 expression. TMPO‐AS1 regulated EC cell progression via downregulating miR‐498 expression.

Conclusions

Collectively, our findings demonstrated that propofol inhibited hypoxia‐induced EC cell mobility through modulation of the TMPO‐AS1/miR‐498 axis, providing a theoretical basis for the treatment of EC.

DEC1: a potential biomarker of malignant transformation in oral leukoplakia

The purpose of this study was to analyze the differential expression of DEC1 in oral normal mucosa (NM), oral leukoplakia (OLK) and oral squamous cell carcinoma (OSCC). Surgically excised specimens from patients with OLK (n = 47), OSCC (n = 30) and oral normal mucosa (n=11) were immunostained for DEC1. The expression of DEC1 protein was evaluated, and its association with the clinicopathological features was analyzed. The expression of DEC1 in NM, OLK and OSCC tissues increased in turn, and significant differences were observed among the groups (P < 0.0001). In terms of the association between DEC1 expression and epithelial dysplasia, DEC1 expression was lower in hyperkeratosis without dysplasia (H-OLK) than in OLK with moderate to severe dysplasia (S-OLK), and these differences were significant (p < 0.05). The expression of DEC1 in OSCC with OLK was significantly higher than that in OSCC without OLK (p < 0.01). Therefore, DEC1 could be a potential biomarker of malignant transformation in the carcinogenesis of OSCC, which may provide a new research direction for the transformation of oral potentially malignant disorders (OPMDs) into OSCC.

Differential expression of ghrelin and GHSR via the mTOR pathway during the dynamic carcinogenic process involving oral, potentially malignant disorders

The purpose was to explore the sequence changes in ghrelin and GHSR in the mTOR signaling pathway during carcinogenesis involving oral, potentially malignant disorders (OPMD). The samples were confirmed through in vivo pathologic tissue screening and diagnosis. The immunohistochemical method was used to detect the expression of the ghrelin/growth hormone secretagogue receptor (GHSR) protein. The expression of ghrelin, GHSR 1α, GHSR 1β, and mammalian target of rapamycin (mTOR) RNA were detected by real-time PCR. The expression of ghrelin, GHSR, mTOR, and phosphorylated mTOR (phosphor-mTOR) protein were detected by Western blot. The expression of ghrelin/GHSR increased gradually in the dynamic process of OPMD carcinogenesis. There was a correlation between the increase in ghrelin, GHSR, mTOR, and phospho-mTOR. The in vivo expression of ghrelin/GHSR protein was the most apparent pathologic change from normal-to-mild, moderate, and severe dysplasia, and finally to the dynamic process from normal-to-mild-to-moderate dysplasia. The in vitro cell experiments based on QPCR results also proved that GHSR 1a functional receptor of ghrelin had a peak expression in LEUK-1 cells. In conclusioin, the close relationship between ghrelin and OPMD carcinogenesis can be used as a new biological target to assess the carcinogenesis of OPMD.

Bioinformatics-based discovery of PYGM and TNNC2 as potential biomarkers of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is an aggressive malignancy with high morbidity and mortality rates and ranks as the sixth most common cancer all over the world. Despite numerous advancements in therapeutic methods, the prognosis of HNSCC patients still remains poor. Therefore, there is an urgent need to have a better understanding of the molecular mechanisms underlying HNSCC progression and to identify essential genes that could serve as effective biomarkers and potential treatment targets. In the present study, original data of three independent datasets were downloaded from the Gene Expression Omnibus database (GEO) and R language was applied to screen out the differentially expressed genes (DEGs). PYGM and TNNC2 were finally selected from the overlapping DEGs of three datasets for further analyses. Transcriptional and survival data related to PYGM and TNNC2 was detected through multiple online databases such as Oncomine, Gene Expression Profiling Interactive Analysis (GEPIA), cBioportal, and UALCAN. Quantitative real-time polymerase chain reaction (qPCR) analysis was adopted for the validation of PYGM and TNNC2 mRNA level in HNSCC tissues and cell lines. Survival curves were plotted to evaluate the association of these two genes with HNSCC prognosis. It was demonstrated that PYGM and TNNC2 were significantly down-regulated in HNSCC and the aberrant expression of PYGM and TNNC2 were correlated with HNSCC prognosis, implying the potential of exploiting them as therapeutic targets for HNSCC treatment or potential biomarkers for diagnosis and prognosis.

Multifaceted Mechanisms of Areca Nuts in Oral Carcinogenesis: the Molecular Pathology from Precancerous Condition to Malignant Transformation

Oral cancer is one of the most frequent malignant diseases worldwide, and areca nut is a primary carcinogen causing this cancer in Southeast Asia. It has been widely reported that areca nut induced several cytotoxic effects in oral cells, including ROS generation, inflammation, tissue hypoxia, DNA damage, and cell invasion. Recently, through chronic exposure model, more extensive pathological effects due to areca nut have been found. These include the induction of autophagy, promotion of epithelial- mesenchymal transition, and facilitation of cancer stemness conversion. Clinical findings support these adverse effects. Oral submucosal fibrosis, a premalignant condition, is prevalent in the area with habitual chewing of areca nuts. Consistently, oral cancer patients with habitual chewing areca nut exhibit more aggressive phenotypes, including resistance to chemo-radiotherapy. In this review, we comprehensively discuss and concisely summarize the up-to-date molecular and cellular mechanisms by which areca nuts contribute to malignant transformation. This review may provide critical information regarding clinical applications in risk assessment, disease prevention, diagnosis, and personalized therapeutics for areca nut-induced oral malignancy.

Assessment of cellular and serum proteome from tongue squamous cell carcinoma patient lacking addictive proclivities for tobacco, betel nut, and alcohol: Case study

The intriguing molecular pathways involved in oral carcinogenesis are still ambiguous. The oral squamous cell carcinoma (OSCC) ranks as the most common type constituting more than 90% of the globally diagnosed oral cancers cases. The elevation in the OSCC incidence rate during past 10 years has an alarming impression on human healthcare. The major challenges associated with OSCC include delayed diagnosis, high metastatic rates, and low 5-year survival rates. The present work foundations on reverse genetic strategy and involves the identification of genes showing expressional variability in an OSCC case lacking addictive proclivities for tobacco, betel nut, and/or alcohol, major etiologies. The expression modulations in the identified genes were analyzed in 16 patients comprising oral pre-cancer and cancer histo-pathologies. The genes SCCA1 and KRT1 were found to down regulate while DNAJC13, GIPC2, MRPL17, IG-Vreg, SSFA2, and UPF0415 upregulated in the oral pre-cancer and cancer pathologies, implicating the genes as crucial players in oral carcinogenesis.

Proteomics-based investigation of multiple stages of OSCC development indicates that the inhibition of Trx-1 delays oral malignant transformation

The majority of cases of oral squamous cell carcinoma (OSCC) develop from oral potentially malignant disorders, which have been confirmed to be involved in chronic oxidative stimulation. However, no effective treatment approaches have been used to prevent the development of dysplasia into cancerous lesions thus far. In the present study, a well-established OSCC model was used to detect proteomics profiles at different stages during oral malignant transformation. Of the 15 proteins that were found to be upregulated in both the dysplasia and carcinoma stages, the oxidative stress-associated proteins, thioredoxin-1 (Trx-1), glutaredoxin-1 and peroxiredoxin-2 were note as the proteins with significant changes in expression Trx-1 was identified to be the most significantly upregulated protein in the precancerous stage. Validation experiments confirmed that Trx-1 was overex-pressed both in dysplasia and cancerous tissue samples, and the inhibition of Trx-1 was able to promote the apoptosis of OSCC cells under hypoxic conditions. Furthermore, the experimental application of a Trx-1-specific inhibitory agent in an animal model led to a lower cancerization rate and a delay in tumor formation. The possible mechanisms were associated with the increased apoptosis via a reactive oxygen species (ROS)-dependent pathway. Taken together, our findings indicate that Trx-1 may be an important target for delaying oral malignant transformation, which provides a novel therapeutic strategy for the prevention and treatment of OSCC.

Adverse Health Effects of Betel Quid and the Risk of Oral and Pharyngeal Cancers

Global reports estimate 600 million betel quid (BQ) chewers. BQ chewing has been demonstrated not only to be a risk factor for cancers of the oral cavity and pharynx and oral potentially malignant disorders (OPMD) but also to cause other cancers and adverse health effects. Herein, we summarized the international comparison data to aid in the understanding of the close relationship between the prevalence of BQ chewing, the occurrence of oral and pharyngeal cancers, and adverse health effects. Potential biomarkers of BQ carcinogens, such as areca nut, alkaloids, and 3-methylnitrosaminopropionitrile (MNPN), are closely associated with human health toxicology. Molecular mechanisms or pathways involving autophagy, hypoxia, COX-2, NF-κB activity, and stemness are known to be induced by BQ ingredients and are very closely related to the carcinogenesis of cancers of oral and pharynx. BQ abuse-related monoamine oxidase (MAO) gene was associated with the occurrence and progress of oral and pharyngeal cancers. In summary, our review article provides important insights into the potential roles of environmental BQ (specific alkaloid biomarkers and nitrosamine products MNPN) and genetic factors (MAO) and offers a basis for studies aiming to reduce or eliminate BQ-related OPMD and oral/pharyngeal cancer incidences in the future.