Integrative analysis of genomic and transcriptomic data of normal, tumour, and co-occurring leukoplakia tissue triads drawn from patients with gingivobuccal oral cancer identifies signatures of tumour initiation and progression.

A thickened, white patch - leukoplakia - in the oral cavity is usually benign, but sometimes (in ~9% of individuals) it progresses to malignant tumour. Because the genomic basis of this progression is poorly understood, we undertook this study and collected samples of four tissues - leukoplakia, tumour, adjacent normal, and blood - from each of 28 patients suffering from gingivobuccal oral cancer. We performed multiomics analysis of the 112 collected tissues (four tissues per patient from 28 patients) and integrated information on progressive changes in the mutational and transcriptional profiles of each patient to create this genomic narrative. Additionally, we generated and analysed whole-exome sequence data from leukoplakia tissues collected from 11 individuals not suffering from oral cancer. Nonsynonymous somatic mutations in the CASP8 gene were identified as the likely events to initiate malignant transformation, since these were frequently shared between tumour and co-occurring leukoplakia. CASP8 alterations were also shown to enhance expressions of genes that favour lateral spread of mutant cells. During malignant transformation, additional pathogenic mutations are acquired in key genes (TP53, NOTCH1, HRAS) (41% of patients); chromosomal-instability (arm-level deletions of 19p and q, focal-deletion of DNA-repair pathway genes and NOTCH1, amplification of EGFR) (77%), and increased APOBEC-activity (23%) are also observed. These additional alterations were present singly (18% of patients) or in combination (68%). Some of these alterations likely impact immune-dynamics of the evolving transformed tissue; progression to malignancy is associated with immune suppression through infiltration of regulatory T-cells (56%), depletion of cytotoxic T-cells (68%), and antigen-presenting dendritic cells (72%), with a concomitant increase in inflammation (92%). Patients can be grouped into three clusters by the estimated time to development of cancer from precancer by acquiring additional mutations (range: 4-10 years). Our findings provide deep molecular insights into the evolutionary processes and trajectories of oral cancer initiation and progression. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Polymorphisms of acetaldehyde dehydrogenase 2 and alcohol dehydrogenase 1B on the malignant transformation of vocal cord leukoplakia: A Chinese cohort.

Severe dysplasia of vocal cord leukoplakia (VCL) is more likely to occur in laryngeal carcinoma. Alcohol dehydrogenase and acetaldehyde dehydrogenase are both important enzymes in alcohol metabolism. This study aimed to investigate the incidence rate of malignant transformation in patients with VCL and the role of drinking habits and ALDH2 and ADH1B genetic polymorphisms in the malignant transformation of VCL. From January 2007 to January 2017, 136 cases of VCL were included in this retrospective analysis. Information on medical history, alcohol and tobacco consumption habits, ALDH2 and ADH1B genotypes, gastroesophageal reflux, and clinical pathological characteristics of VCL was collected. As a result, patients had a median follow-up of 9.6 years (interquartile range: 7.5-12.5 years). Twenty-three of 136 VCL patients finally developed laryngeal carcinoma, resulting in a cumulative malignant transformation rate of 16.9%. Cox regression analysis demonstrated that the independent risk factors for the malignant transformation of VCL included age over 60 years (hazard ratio [HR]: 13.872, p < 0.001), ALDH2 *2 allele status (HR: 9.694, p < 0.001), alcohol (HR: 10.011, p < 0.001) and tobacco (HR: 8.869, p < 0.001) exposure after operation, and drinking frequency (HR: 2.178, p = 0.016). Therefore, among patients over 60 years old, an ALDH2-inactivating mutation and excessive ethanol and tobacco consumption are potential contributors to the malignant transformation of VCL.

The Role of Keratin-8 and Keratin-18 Polymorphisms and Protein Levels in the Occurrence and Progression of Vocal Leukoplakia.

OBJECTIVE: This study aimed to evaluate the association between the single-nucleotide polymorphism (SNP) and tissue protein level of keratin-8/18 and the occurrence and progression of vocal leukoplakia. METHODS: The case-control study enrolled 158 patients with vocal leukoplakia, 326 patients with laryngeal squamous cell carcinoma (LSCC), and 268 healthy controls, which were tested for genotype analysis with keratin-8 and keratin-18 gene polymorphisms using pyrosequencing. The tissue protein expression levels of keratin-8 and keratin-18 were evaluated using immunohistochemistry. RESULTS: The keratin-8 SNP RS1907671 showed an obvious increased risk for vocal leukoplakia (OR 1.56, p = 0.002), while the other SNPs (RS2035875, RS2035878, RS4300473) were tested as protective factors for vocal leukoplakia and LSCC (OR <1, p < 0.05). In keratin-18 SNP test, both RS2070876 and RS2638526 polymorphisms demonstrated decreased risks for vocal leukoplakia and LSCC (OR <1, p < 0.05). The protein levels of keratin-8 and keratin-18 in vocal leukoplakia group were significantly higher than those of the LSCC group (p < 0.05). CONCLUSIONS: Keratin-8 and keratin-18 polymorphisms and protein levels are associated with the occurrence and progression of vocal leukoplakia.

Significance of Cytokeratin-1 Single-Nucleotide Polymorphism and Protein Level in Susceptibility to Vocal Leukoplakia and Laryngeal Squamous Cell Carcinoma.

OBJECTIVE: To investigate the association between the cytokeratin (CK)-1 single-nucleotide polymorphism (SNP), the protein level of CK-1 and the risk of vocal leukoplakia and laryngeal squamous cell carcinoma (LSCC). METHODS: In this case-control study, 155 patients with vocal leukoplakia, 323 patients with LSCC, and 266 healthy controls were genotyped for the CK-1 (SNP RS14024) gene using pyrosequencing. The protein expression level of CK-1 was analyzed in vocal leukoplakia, LSCC, and vocal polyp patients by immunohistochemistry (IHC). RESULTS: Of the CK-1 RS14024 polymorphism, the heterozygote AG and homozygote GG genotype exhibited a significantly increased risk of LSCC (AG: OR = 2.16, p = 0.014; GG: OR = 2.15, p = 0.018) compared to normal controls. A higher protein expression level of CK-1 was detected in patients with LSCC compared to vocal leukoplakia and polyps (both p < 0.001), and a significant increasing trend of CK-1 protein expression level from mild-moderate dysplasia to moderate-severe dysplasia in vocal leukoplakia patients was also observed (p = 0.006). CONCLUSIONS: This study demonstrates that the CK-1 SNP and high protein expression levels are associated with vocal leukoplakia and LSCC and promote the transformation from vocal leukoplakia to LSCC in a Chinese Han population.

Association of Decreased Expression of Serum miR-9 with Poor Prognosis of Oral Squamous Cell Carcinoma Patients.

BACKGROUND: Dysregulation of miR-9 is a common feature of many types of cancers, including oral squamous cell carcinoma (OSCC). However, whether the expression level of serum miR-9 is changed in patients with OSCC remains unknown. MATERIAL/METHODS: Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to examine the expression level of serum miR-9 in OSCC patients, oral leukoplakia (OLK) patients, and healthy volunteers, then we evaluated the association between serum miR-9 expression level and clinical outcome of OSCC patients. RESULTS: The expression level of serum miR-9 was significantly downregulated in patients with OSCC or OLK in comparison with healthy controls (P<0.01). Serum miR-9 expression level was associated with various clinicopathological parameters, including T stage (P=0.013), lymph node metastasis (P=0.002), and TNM stage (P=0.007). In addition, the OSCC patients in the low serum miR-9 expression group had poorer overall survival rate (P=0.022) and disease-free survival rate (P=0.004) compared with those in the high serum miR-9 expression group. Multivariate analysis showed that serum miR-9 was an independent prognostic factor for OSCC. CONCLUSIONS: Serum miR-9 was downregulated in patients with OSCC and patients with OLK. In addition, low serum miR-9 was correlated with poor prognosis of OSCC, indicating miR-9 might play a tumor suppressive role in OSCC and can serve as a promising biomarker for this deadly disease.

Association between risk of oral precancer and genetic variations in microRNA and related processing genes.

BACKGROUND: MicroRNAs have been implicated in cancer but studies on their role in precancer, such as leukoplakia, are limited. Sequence variations at eight miRNA and four miRNA processing genes were studied in 452 healthy controls and 299 leukoplakia patients to estimate risk of disease. RESULTS: Genotyping by TaqMan assay followed by statistical analyses showed that variant genotypes at Gemin3 and mir-34b reduced risk of disease [OR = 0.5(0.3-0.9) and OR = 0.7(0.5-0.9) respectively] in overall patients as well as in smokers [OR = 0.58(0.3-1) and OR = 0.68(0.5-0.9) respectively]. Among chewers, only mir29a significantly increased risk of disease [OR = 1.8(1-3)]. Gene-environment interactions using MDR-pt program revealed that mir29a, mir34b, mir423 and Xpo5 modulated risk of disease (p < 0.002) which may be related to change in expression of these genes as observed by Real-Time PCR assays. But association between polymorphisms and gene expressions was not found in our sample set as well as in larger datasets from open access platforms like Genevar and 1000 Genome database. CONCLUSION: Variations in microRNAs and their processing genes modulated risk of precancer but further in-depth study is needed to understand mechanism of disease process.

Comparative evaluation of genotoxicity by micronucleus assay in the buccal mucosa over comet assay in peripheral blood in oral precancer and cancer patients.

Early detection and quantification of DNA damage in oral premalignancy or malignancy may help in management of the disease and improve survival rates. The comet assay has been successfully utilised to detect DNA damage in oral premalignant or malignancy. However, due to the invasive nature of collecting blood, it may be painful for many unwilling patients. This study compares the micronucleus (MN) assay in oral buccal mucosa cells with the comet assay in peripheral blood cells in a subset of oral habit-induced precancer and cancer patients. For this, MN assay of exfoliated epithelial cells was compared with comet assay of peripheral blood leucocytes among 260 participants, including those with oral lichen planus (OLP; n = 52), leukoplakia (LPK; n = 51), oral submucous fibrosis (OSF; n = 51), oral squamous cell carcinoma (OSCC; n = 54) and normal volunteers (n = 52). Among the precancer groups, LPK patients showed significantly higher levels of DNA damage as reflected by both comet tail length (P < 0.0001) and micronuclei (MNi) frequency (P = 0.0009). The DNA damage pattern in precancer and cancer patients was OLP < OSF < LPK < OSCC, and with respective oral habits, it was multiple habits > cigarette + khaini > cigarette smokers > areca + khaini > areca. There was no significant difference in the comet length and MNi frequency between males and females who had oral chewing habits. An overall significant correlation was observed between MNi frequency and comet tail length with r = 0.844 and P < 0.0001. Thus, the extent of DNA damage evaluation by the comet assay in peripheral blood cells is perfectly reflected by the MN assay on oral exfoliated epithelial cells, and MNi frequency can be used with the same effectiveness and greater efficiency in early detection of oral premalignant conditions.

Mutation of a type II keratin gene (K6a) in pachyonychia congenita.

Pachyonychia congenita (PC) is a rare autosomal dominant condition characterized by multiple ectodermal abnormalities. Patients with Jadassohn-Lewandowsky Syndrome (MIM #167200; PC-1) have nail defects (onchyogryposis), palmoplantar hyperkeratosis, follicular hyperkeratosis and oral leukokeratosis. Those with the rarer Jackson-Lawler Syndrome (MIM #167210; PC-2) lack oral involvement but have natal teeth and cutaneous cysts. Ultra-structural studies have identified abnormal keratin tonofilaments and linkage to the keratin gene cluster on chromosome 17 has been found in PC families. Keratins are the major structural proteins of the epidermis and associated appendages and the nail, hair follicle, palm, sole and tongue are the main sites of constitutive K6, K16 and K17 expression. Furthermore, mutations in K16 and K17 have recently been identified in some PC patients. Although we did not detect K16 or K17 mutations in PC families from Slovenia, we have found a heterozygous deletion in a K6 isoform (K6a) in the affected members of one family. This 3 bp deletion (AAC) in exon 1 of K6a removes a highly conserved asparagine residue (delta N170) from position 8 of the 1A helical domain (delta N8). This is the first K6a mutation to be described and this heterozygous K6a deletion is sufficient to explain the pathology observed in this PC-1 family.

Genome-wide DNA methylation profiling of HPV-negative leukoplakia and gingivobuccal complex cancers.

BACKGROUND: Gingivobuccal complex oral squamous cell carcinoma (GBC-OSCC) is an aggressive malignancy with high mortality often preceded by premalignant lesions, including leukoplakia. Previous studies have reported genomic drivers in OSCC, but much remains to be elucidated about DNA methylation patterns across different stages of oral carcinogenesis. RESULTS: There is a serious lack of biomarkers and clinical application of biomarkers for early detection and prognosis of gingivobuccal complex cancers. Hence, in search of novel biomarkers, we measured genome-wide DNA methylation in 22 normal oral tissues, 22 leukoplakia, and 74 GBC-OSCC tissue samples. Both leukoplakia and GBC-OSCC had distinct methylation profiles as compared to normal oral tissue samples. Aberrant DNA methylation increases during the different stages of oral carcinogenesis, from premalignant lesions to carcinoma. We identified 846 and 5111 differentially methylated promoters in leukoplakia and GBC-OSCC, respectively, with a sizable fraction shared between the two sets. Further, we identified potential biomarkers from integrative analysis in gingivobuccal complex cancers and validated them in an independent cohort. Integration of genome, epigenome, and transcriptome data revealed candidate genes with gene expression synergistically regulated by copy number and DNA methylation changes. Regularised Cox regression identified 32 genes associated with patient survival. In an independent set of samples, we validated eight genes (FAT1, GLDC, HOXB13, CST7, CYB5A, MLLT11, GHR, LY75) from the integrative analysis and 30 genes from previously published reports. Bisulfite pyrosequencing validated GLDC (P = 0.036), HOXB13 (P < 0.0001) promoter hypermethylation, and FAT1 (P < 0.0001) hypomethylation in GBC-OSCC compared to normal controls. CONCLUSIONS: Our findings identified methylation signatures associated with leukoplakia and gingivobuccal complex cancers. The integrative analysis in GBC-OSCC identified putative biomarkers that enhance existing knowledge of oral carcinogenesis and may potentially help in risk stratification and prognosis of GBC-OSCC.

Genetic polymorphisms and protein levels in vocal fold leukoplakia: a systematic review.

Vocal fold leukoplakia (VFL) has a risk of malignant transformation. Therefore, patients can have symptoms such as dysphonia, vocal strain, difficulty breathing, and dysphagia. Additionally, there is a genetic predisposition that can be associated with genetic polymorphisms. We aimed to evaluate the influence of genetic polymorphisms and protein levels in the etiology of VFL. Our study followed the PRISMA checklist and was registered on PROSPERO database. The questions were: "Are genetic polymorphisms involved in the etiology of VFL? Are protein levels altered in patients with VFL?". Eligibility criteria were case control studies that compared the presence of polymorphisms or/and protein levels of subjects diagnosed with VFL and healthy controls. Of the 905 articles retrieved, five articles with a total of 1038 participants were included in this study. The C allele of the single nucleotide polymorphisms (SNP)-819 T/C IL-10, A allele of the SNP -592 A/C IL-10, CT genotype of the SNP rs11886868 C/T BCL11A, GG genotype of the SNP rs4671393 A/G BCL11A, LL genotype, and L allele of (GT)n repeat polymorphisms of the HO-1 were risk factors for VFL development. Nevertheless, there was a lack of association between VFL and the -1082 A/G IL-10, rs14024 CK-1, and -309 T/G Mdm2 SNPs. The concentrations of the MDM2, BCL11A, and HO-1 proteins were modified, while IL-10 levels were normally expressed in these subjects. In conclusion, most markers evaluated in this review could be potential indicators to develop effective therapies, avoiding a malignant transformation of the lesion.

Pachyonychia congenita with laryngeal obstruction.

Pachyonychia congenita is a rare genodermatosis that can affect the larynx. Laryngeal obstruction is very unusual with only a few cases reported. A 2-year-old girl presented with typical clinical features of pachyonychia congenita shortly after birth. At age 9 months, following an upper respiratory infection, she developed stridor and hoarseness and was found to have severe laryngeal obstruction, which was felt to be secondary to pachyonychia congenita based on direct laryngoscopy and laryngeal biopsy. Leukokeratosis of her larynx was treated with CO(2) laser on three occasions, with improvement in her respiratory distress after each treatment. This report is the first case of pachyonychia congenita with laryngeal obstruction in which the gene mutation has been established (a deletional mutation in K6a), confirming that laryngeal obstruction can occur in PC-1.

DNA aneuploidy with image cytometry for detecting dysplasia and carcinoma in oral potentially malignant disorders: A prospective diagnostic study.

BACKGROUND: Current evidence on diagnostic value of aneuploidy with DNA image cytometry (ICM) using brushings for oral potentially malignant disorders (OPMD) is limited by sample size and inconsistent classification criteria of aneuploidy. This study aimed to explore the optimal cut-off values of DNA content and evaluate the diagnostic accuracy of DNA-ICM for detecting dysplasia and/or carcinoma in OPMD. MATERIALS AND METHODS: A total of 401 consecutive patients with OPMD were enrolled in this prospective diagnostic study. Brushing and biopsy sample form each patient was processed by DNA-ICM and histological examination respectively. RESULTS: When the optimal cut-off of at least one aneuploid cell with DNA index (DI) ≥2.3, the area under the curves (AUC) was 0.735 and positive predictive value was 92.7% for detecting dysplasia within OPMD. When the optimal cut-off of at least one aneuploid cell with DI ≥ 3.5, the AUC was 0.851 and negative predictive values was 96.8% for detecting carcinoma within OPMD. Importantly, multivariate analysis revealed that aneuploidy with DI ≥ 2.3 in OPMD was significantly associated with dysplasia risk (adjusted OR, 5.52; 95%CI, 2.90-10.51; P < .001), and aneuploidy with DI ≥ 3.5 in OPMD was strongly associated with malignant risk (adjusted OR, 21.05; 95%CI, 9.34-47.41; P < .001). CONCLUSIONS: This largest-scale diagnostic study optimized the criteria of aneuploidy cytology for noninvasive detection of oral dysplasia and carcinoma within OPMD. DNA aneuploidy in OPMD was an independent marker that strongly associated with oral dysplasia/carcinoma. Our findings suggest that DNA-ICM may serve as a useful noninvasive adjunctive tool for oral cancer and OPMD screening.

Polymorphisms at p53, p73, and MDM2 loci modulate the risk of tobacco associated leukoplakia and oral cancer.

Polymorphisms at loci controlling cellular processes such as cell cycle, DNA repair, and apoptosis may modulate the risk of cancer. We examined the association of two linked polymorphisms (G4C14-A4T14) at p73 and one polymorphism (309G > T) at MDM2 promoter with the risk of leukoplakia and oral cancer. The p73 and MDM2 genotypes were determined in 197 leukoplakia patients, 310 oral cancer patients and in 348 healthy control subjects. The p73 GC/AT genotype increased the risk of leukoplakia (OR = 1.6, 95% CI = 1.1-2.3) and oral cancer (OR = 2.4, 95% CI = 1.7-3.3) but the 309G > T MDM2 polymorphism independently could not modify the risk of any of the diseases. Stratification of the study population into subgroups with different tobacco habits showed that the risk of the oral cancer is not modified further for the individuals carrying p73 risk genotype. However, leukoplakia patients with smokeless tobacco habit showed increased risk with combined GC/AT and AT/AT (OR = 3.0, 95% CI = 1.3-7.0) genotypes. A combined analysis was done with our previous published data on p53 codon 72 pro/arg polymorphism. Analysis of pair wise genotype combinations revealed increase in risk for specific p73-MDM2 and p73-p53 genotype combinations. Finally, the combined three loci analyses revealed that the presence of at least one risk allele at all three loci increases the risk of both leukoplakia and oral cancer.

Prevalence of CYP1A1 and GST polymorphisms in the population of northeastern India and susceptibility of oral cancer.

Individual cancer susceptibility is the result of several host factors, including differences in lifestyle habits and genetic susceptibility. There is a correlation between CYP1A1 polymorphism (MspI) and oral cancer susceptibility. Individuals carrying the deletions of GSTM1 and GSTT1 are at high risk of developing oral cancers. In the present study on healthy tribal and nontribal individuals of Assam, we found that the genetic variation of GSST polymorphisms is evident (p = 0.20) with differential dose of toxic exposure. Prevalence of different polymorphic alleles of CYP1A1 also proves the same result. A mini-case-control study with very small sample size showed no marked increase in the risk of developing oral cancer as the frequencies of the studied GST genotypes did not show any statistical significance. But GSTT1-null genotypes were found to have higher risk of developing leukoplakia (OR 1.94, 95% CI 2.61-18.54). CYP1A1 genotype m2 allele was also not found to be associated with the risk of developing leukoplakias in the population.

Losses of 3p14 and 9p21 as shown by fluorescence in situ hybridization are early events in tumorigenesis of oral squamous cell carcinoma and already occur in simple keratosis.

Tumorigenesis of oral squamous cell carcinoma (OSCC) has been postulated to represent a multistep process driven by the accumulation of carcinogen-induced genetic changes. Alterations of the 3p14 fragile site containing the fragile histidine triade gene and of the 9p21 tumor suppressor locus containing methylthioadenosine phosphorylase, p16 and p15 characteristically occur in oral leukoplakia, a known precursor of OSCC, and are at present considered to indicate the transition from simple keratosis (hyperplasia) to dysplasia. The aim of the study was to evaluate the occurrence of losses of 3p14 and 9p21 and to evaluate polysomies 3 and 9 in leukoplakias using highly sensitive fluorescence in situ hybridization (FISH) probes. Examining 67 leukoplakias (24 hyperplasias, 33 dysplasias, 10 in situ carcinomas), control tissues of oral mucosa from infants and adults as well as invasive carcinomas and normal epithelia of tumor patients with locus specific FISH probes targeting 3p14 and 9p21, and centromeric probes for chromosomes 3 and 9 we could demonstrate that losses of these sites appeared very early in the tumorigenesis of OSCC and were already present in the great majority of simple keratoses. Polysomy 3 occurring more frequently than polysomy 9 was characteristic of dysplasia and in situ carcinomas and thus seems to follow losses of 3p14 and 9p21 during oral squamous cell carcinogenesis.

Expression of Mcm7 and Cdc6 in oral squamous cell carcinoma and precancerous lesions.

BACKGROUND: The present study aimed at evaluating the clinical importance of Mcm7 and Cdc6 expression in oral squamous cell carcinoma (OSCC) and precancerous lesions. MATERIALS AND METHODS: RT-PCR and immunohistochemistry analysis were performed on 47 frozen samples and 98 paraffin-embedded samples to evaluate the mRNA and protein expressions of Mcm7 and Cdc6. RESULTS: RT-PCR and immunohistochemistry indicated positive expressions of Mcm7 mRNA and protein in normal oral mucosa, precancerous lesions and OSCC. Significant differences were found between all the groups. Cdc6 mRNA and protein had low expressions in normal oral mucosa but were highly expressed in precancerous lesions and OSCC. Mcm7 and Cdc6 expressions in the lymph node metastasis cases were significantly higher than those of the nonmetastatic carcinomas. CONCLUSION: High expressions of Mcm7 and Cdc6 are correlated with the development and metastasis of OSCC and may become a molecular marker for the early diagnosis and prognosis prediction for OSCC.

Differences in gene expression profile between vocal cord Leukoplakia and normal larynx mucosa by gene chip.

BACKGROUND: Long non-coding RNAs (lncRNAs) play an important role in tumorigenesis. Vocal cord leukoplakia is a precancerous lesion in otolaryngological practice. Till now, the expression patterns and functions of lncRNAs in vocal cord leukoplakia have not been well understood. In this study, we used microarrays to investigate the aberrantly expressed lncRNAs and mRNAs in vocal cord leukoplakia and adjacent non-neoplastic tissues. METHODS: Gene Ontology and pathway analyses were performed to determine the significant function and pathways of the differentially expressed mRNAs. qRT-PCR was performed to further validate the expression of selected lncRNAs and mRNAs in vocal cord leukoplakia. RESULTS: Our study identified 170 differentially expressed lncRNAs and 99 differentially expressed mRNAs, including 142 up-regulated lncRNAs and 28 down-regulated lncRNAs, and 54 up-regulated mRNAs and 45 down-regulated mRNAs. Among these, XLOC_000605 and DLX6-AS1 were the most aberrantly expressed lncRNAs. Furthermore, we identified an antisense lncRNA (LOC100506801), an enhancer-like lncRNA (AK057351) and three long intergenetic noncoding RNAs including XLOC_008001, XLOC_011989 and XLOC_007341. CONCLUSIONS: Our results revealed that many lncRNAs were differentially expressed between vocal cord leukoplakia tissues and normal tissue, suggesting that they may play a key role in vocal cord leukoplakia tumorigenesis.

MicroRNAs and their role in the malignant transformation of oral leukoplakia: a scoping review

Background: MiRNAs are small non-coding RNAs that regulate gene expression at the post-transcriptional level and have been associated with malignant transformation of oral epithelial precursor lesions such as oral leukoplakia. The aim was to perform a scoping review of the contemporary literature about the different roles of miRNAs during the malignant transformation of oral leukoplakia. Material and Methods: We conducted a systematic search with the following MeSH terms: ‘oral leukoplakia’, ‘carcinoma in situ’, ‘microRNAs’, ‘mouth neoplasms’ and ‘epithelial–mesenchymal transition’ in PubMed/MEDLINE, EMBASE and SpringerLink. Results: Fifteen articles were included for analysis, among which in vivo and in vitro articles were included. A total of 21 different miRNAs were found to be involved in the malignant transformation process of oral leukoplakia. Regarding their possible effects, 6 miRNAs were classified as oncogenic, 5 as tumour suppressors and 10 were related to epithelial–mesenchymal transition, invasion and migration. Conclusions: Based on the current review, we concluded that miRNAs-21, 345, 181-b and 31* seem to be potential markers of malignant transformation of oral leukoplakia. However, further clinical prospective studies are needed in order to validate their utility as prognostic biomarkers.(AU)

Overexpression of PAX5 in oral carcinogenesis.

The oncogenic transcription factor PAX5 is an important developmental regulator and is implicated in the pathogenesis of several malignancies. The PAX5 gene is involved in medulloblastoma, non-Hodgkin's lymphoma, transitional cell carcinoma of the bladder, neuroblastoma, breast cancer and SCC. In the current study, to determine the potential involvement of PAX5 in oral squamous-cell carcinoma (OSCC) and leukoplakias, we evaluated the status of PAX5 mRNA and protein expression in OSCC cell lines, human primary OSCCs, and leukoplakias by real-time quantitative reverse transcriptase-polymerase chain reaction, Western blot analysis, and immunohistochemistry. A significant increase in PAX5 expression was observed in all OSCC-derived cell lines examined compared to human normal oral keratinocytes (HNOKs). In immunohistochemistry, 78% of tumors and 42% of leukoplakias examined were positive for PAX5, while no immunoreaction was observed in corresponding normal tissues. The results suggest that PAX5 plays an important role during oral carcinogenesis, especially in the early stage, and that the gene may have potential as a biomarker and therapeutic target for OSCC.