The emerging role of oral microbiota in oral cancer initiation, progression and stemness.

Oral squamous cell carcinoma (OSCC) is the most prevalent malignancy among the Head and Neck cancer. OSCCs are highly inflammatory, immune-suppressive, and aggressive tumors. Recent sequencing based studies demonstrated the involvement of different oral microbiota in oral cavity diseases leading OSCC carcinogenesis, initiation and progression. Researches showed that oral microbiota can activate different inflammatory pathways and cancer stem cells (CSCs) associated stemness pathways for tumor progression. We speculate that CSCs and their niche cells may interact with the microbiotas to promote tumor progression and stemness. Certain oral microbiotas are reported to be involved in dysbiosis, pre-cancerous lesions, and OSCC development. Identification of these specific microbiota including Human papillomavirus (HPV), Porphyromonas gingivalis (PG), and Fusobacterium nucleatum (FN) provides us with a new opportunity to study the bacteria/stem cell, as well as bacteria/OSCC cells interaction that promote OSCC initiation, progression and stemness. Importantly, these evidences enabled us to develop in-vitro and in-vivo models to study microbiota interaction with stem cell niche defense as well as CSC niche defense. Thus in this review, the role of oral microbiota in OSCC has been explored with a special focus on how oral microbiota induces OSCC initiation and stemness by modulating the oral mucosal stem cell and CSC niche defense.

CircHLA-C: A significantly upregulated circRNA co-existing in oral leukoplakia and oral lichen planus.

BACKGROUND: Oral leukoplakia (OLK) and oral lichen planus (OLP) are common precancerous lesions of the oral mucosa. The role of circular RNAs (circRNAs) in OLK and OLP is unclear. The aim of this study was to evaluate the circRNA expression profiles of OLK and OLP, and further explore the potential role of circRNAs in the pathogenesis of these two diseases. METHODS: High throughput sequencing technology was performed to detect the differentially expressed circRNA in OLK (n = 6), OLP (n = 6), oral squamous cell carcinoma (n = 6), and normal oral mucosa tissues (n = 6). Expression of selected circRNAs was validated by qRT-PCR, enzyme tolerance assay, and Sanger sequencing. Expanded sample size validation was done in 20 tissue pairs. The biological processes and signal pathways involved in differential circRNA were analyzed by GO and KEGG enrichment. TargetScan and MiRanda were used to predict miRNAs downstream of circRNA and draw competitive endogenous RNA network diagram. RESULTS: Forty-nine circRNAs were significantly altered in OLK and OLP, including 30 upregulated and 19 downregulated circRNAs. The five selected circRNAs were validated by qRT-PCR, Sanger sequencing, and RNase R assay. GO and KEGG analyses indicated that the upregulated circHLA-C may be involved in the biological process of immune function of OLK and OLP. Bioinformatics analysis indicated that circHLA-C may be involved in the progression of OLK and OLP as a ceRNA. In validation with expanded sample size, PCR results showed that circHLA-C expression was significantly upregulated in OLK and OLP. ROC analysis indicated that circHLA-C has potential diagnostic value with good accuracy and specificity. CONCLUSION: Our study revealed that circHLA-C is the most significantly upregulated circRNA co-existing in OLK and OLP, and we preliminarily discuss the role of circHLA-C in the etiopathogenesis and progression of OLK and OLP.

Comprehensive bioinformatics analysis combined with experimental validation to screen biomarkers for malignant transformation of oral leukoplakia.

Oral leukoplakia (OLK) is the most common potentially malignant disorders in the oral cavity. This study aimed to screen the key genes of OLK malignant transformation using the Gene Expression Omnibus (GEO) database and experiments. In this study, the GEO database was employed to screen OLK malignant transformation-related genes, which were subsequently identified with a series of bioinformatic analyses. External validation showed that the model based on LAPTM4B, NR3C1, and COX6A1 had high accuracy in diagnosing OLK malignant transformation. Furthermore, the DMBA-induced potentially malignant disorders and OSCC models in vivo and real-time PCR experiment in vitro further verified the database analysis results. In conclusion, three key genes (LAPTM4B, NR3C1, and COX6A1) were screened as potential biomarkers for the diagnosis and treatment of OLK malignant transformation.

Mesenchymal stem cell-exosome-mediated matrix metalloproteinase 1 participates in oral leukoplakia and carcinogenesis by inducing angiogenesis.

BACKGROUND: In the malignant progression of oral leukoplakia (OLK) to oral squamous cell carcinoma (OSCC), the density of microvessels and expression of angiogenesis-related molecules increases. Emerging evidence indicates that mesenchymal stem cells (MSCs) play an indispensable role in the tumor microenvironment. However, the role and mechanism of action of oral MSCs in inducing angiogenesis remain unclear. Therefore, it is necessary to explore the molecules and mechanisms that play a role in the tissue microenvironment. METHODS: Exosomes were collected from normal oral mucosa (N-Exo), OLK (OLK-Exo), and OSCC (Ca-Exo) MSCs, and their pro-angiogenic capacity was evaluated in human umbilical vein endothelial cells (HUVECs) and a subcutaneously implanted tumor model in nude mice. Quantitative proteomics analysis was used to compare the exosome-derived proteins between N-Exo, OLK-Exo, and Ca-Exo. RESULTS: Compared with that of the N-Exo and control, OLK-Exo and Ca-Exo treatment significantly promoted HUVEC migration, invasion, and tube-formation capability. In the nude mice model, immunofluorescence of CD31 showed that OLK-Exo and Ca-Exo substantially improved neovascularization around the grafts. Quantitative proteomics analysis revealed that matrix metalloproteinase 1 (MMP1) levels were significantly higher in the OLK-Exo and Ca-Exo groups than in the N-Exo groups. Silencing MMP1 expression reversed the functional promoting effect of OLK-Exo and Ca-Exo on HUVECs. CONCLUSION: Exosomes from OLK-MSCs and Ca-MSCs have a stronger pro-angiogenic ability through high MMP1 content. This new finding provides insight into the intervention with the secretion of MSC-derived exosomes, which may be an innovative strategy for carcinogenesis.

Comprehensive analysis of circular RNA in oral leukoplakia: upregulated circHLA-C as a potential biomarker for diagnosis and prognosis.

BACKGROUND: Emerging evidence indicates that circular RNAs (circRNAs) play an indispensable role in a variety of tumors, yet the function of circRNAs in premalignant lesions is still obscure. Oral leukoplakia (OLK) is one of the most common premalignant lesions of the oral mucosa. Our study aimed to comprehensively investigate whether circRNAs contribute to the occurrence and development of OLK. METHODS: We obtained six pairs of OLK and normal oral mucosal (NOM) tissue samples and subjected them to high-throughput sequencing to detect the expression of circRNA. In total, 26 pairs of NOM and OLK tissues were used for validation. Key circRNAs were selected and further validated by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), ribonuclease (RNase) R digestion, and Sanger sequencing. Visualization analysis of circular human leukocyte antigen-C (circHLA-C) was performed in the UCSC Genome Browser (genome.ucsc.edu). Functional analysis of differentially expressed (DE) circRNAs were processed by Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Furthermore, TargetScan (www.targetscan.org) was applied to predict targeted micro RNAs (miRNAs) and messenger RNAs (mRNAs) of circRNAs and a competing endogenous RNA (ceRNA) network related with identified circRNAs was constructed in Cytoscape (v2.8.0). RESULTS: Profile data showed that 366 circRNAs were significantly altered in OLK tissues, including 65 upregulated and 301 downregulated circRNA transcripts. Compared with sequencing results, seven selected circRNAs expressed the same changing tendency. The amplest upregulated circRNA in our sequencing data, circHLA-C, was confirmed through back-splice junction sequences by Sanger sequencing after RNase R digestion. Correlation analysis demonstrated that circHLA-C correlated positively with the degree of dysplasia. Furthermore, receiver operating characteristic (ROC) curve analysis indicated that circHLA-C had potential diagnostic value with excellent accuracy and specificity. CONCLUSIONS: According to the literature, we were the first to uncover the expression profiles of circRNAs in OLK. Our research performed a comprehensive bioinformatics analysis of DE circRNAs in OLK and identified circHLA-C as a promising diagnostic biomarker with potential as a therapeutic genetic target for OLK.

Immunohistochemical analysis of dendritic cells in oral leukoplakia tissues / 实用口腔医学杂志

Objective:To investigate the functional status of dendritic cells(DCs)in oral leukoplakia(OLK)tissues.Methods:The expression of DC-specific markers CD1 a,CD209,CD1 23 and CD83 in 20 cases of OLK with abnormal dysplasia,1 0 with simple dys-plasia and 1 0 of normal oral mucosa tissues was examined by immunohistochemistry.Results:CD1 a and CD209 positive DCs were found in all cases.More CD1 a positive Langehans cells(LCs)in lamina propria were found in OLK with abnormal dysplasia than in normal o-ral mucosa and OLK with simple dysplasia(P <0.01 ).A great mount of CD209 positive stromal DCs were recruited in OLK.There was no CD83 positive and CD1 23 positive cell in normal oral mucosa,however,CD83 positive mature DCs and CD1 23 positive plasmacytoid DCs(PDCs)were observed in OLK(P <0.01 ).Conclusion:OLK is characterized by the recruitment of different subsets of DCs,the different DC subsets may play an important role in the development of OLK.