Xabier Marichalar-Mendia

Oral cancer and polymorphism of ethanol metabolising genes

Oral cancer is the sixth most common cancer worldwide and a major health problem in some parts of the world. Epidemiological studies have shown that habitual alcohol consumption could be a risk factor in oral carcinogenesis, although the true involvement of alcohol is unknown. Via alcohol dehydrogenase (ADH) and cytochrome P450 oxidase (CYP) alcohol is metabolized to acetaldehyde, a highly toxic compound, which plays an important role in carcinogenesis. Subsequently, and during the metabolizing process, acetaldehyde becomes acetate by acetaldehyde dehydrogenase (ALDH). Therefore, acetaldehyde levels are determined mainly by the action of ADH, CYP and ALDH. Recently, several studies have found that certain polymorphisms of genes encoding these enzymes confer a higher or lower metabolic activity and therefore different risk for certain malignancies such as oral cancer. In this review, we analyze the polymorphisms of alcohol metabolising enzymes in relation susceptibility to an oral cancer.

Role of cytochrome P‐450 genetic polymorphisms in oral carcinogenesis

Oral cancer is one of the most frequent head and neck cancers, and epidemiological studies have shown that smoking is a major risk factor in this pathology. However, as not all smokers develop oral cancer, some individuals must be more susceptible to develop this disease. This individual susceptibility has been related to different genetic variants in metabolizing enzymes. The cytochrome P-450 (CYP) family of enzymes metabolizes tobacco-related carcinogens producing reactive metabolites, which could cause DNA damage. Because of their functional role in the metabolism of tobacco-related compounds, the genetic polymorphisms found in the genes that code for CYP enzymes have been suggested to modulate oral cancer risk and contribute to individual susceptibility. In this review, we analyze and update the available evidence in the literature regarding the polymorphisms of CYP genes in relation to the susceptibility of developing oral cancer.

Caries and Candida colonisation in adult patients in Basque Country (Spain)

Candida albicans is one of the most frequent pathogens of the oral cavity, as a major cause of opportunistic disease. Moreover, Candida could be a cofactor of common oral diseases, such as dental caries. The aim of this study was to analyse the oral yeast colonisation in adults with dental caries and to evaluate its relationship with this clinical entity. We studied 190 patients distributed into controls (58 patients) and patients with caries (132 patients). Oral samples were collected by oral rinse and cultured in a chromogenic agar. C. albicans was the most prevalent species isolated from oral specimens in both groups. Patients with caries had a greater Candida colonisation (74 patients, 56.1%), than persons without caries (18 patients, 31%, P < 0.01). Patients with caries were significantly more colonised by non‐C. albicans species than individuals without caries (P = 0.006). Moreover, the diversity of Candida species was richer in patients suffering from caries. The odds ratio of the colonisation of patients with caries was 3.144 (95% CI 1.525–5.478). There is a significant clinical correlation between dental caries and oral Candida colonisation in adults.

Polymorphisms in alcohol and tobacco metabolism genes in head and neck cancer in the Basque Country

BACKGROUND The Basque Country has one of the highest rates of head and neck squamous cell carcinoma (HNSCC) in Europe, although tobacco and alcohol consumption are not high when compared to other European countries where HNSCC incidence is lower. Our aim was to determine the role of genetic variation with regard to the metabolism of alcohol and carcinogens from tobacco smoke in the Basque Country. METHODS Fourteen polymorphisms in alcohol or tobacco metabolism genes were genotyped in 84 HNSCC patients and 242 healthy individuals from the Basque Country. RESULTS ADH1B histidine allele (rs1229984), CYP2E1 rs3813867 heterozygous genotype, and GSTT1 deletion conferred protection against HNSCC (OR: 0.318 [0.04-0.75], OR: 0.13 [0.02-0.94], and OR: 0.12 [0.02-0.60], respectively) while GSTP1 (rs1695) Val/Val genotype was related to an increased risk (OR: 4.12 [1.11-15.31]). Regarding alcohol and tobacco habits, GSTT1 deletion was associated with tobacco usage, while the 3 polymorphisms tested in ALDH2 were associated with alcohol consumption. However, genotypic distributions of these 7 SNPs did not differ from those observed for other Caucasian populations where HNSCC incidence is lower. CONCLUSIONS The identified genotypic variations in alcohol and tobacco metabolizing genes only by themselves do not seem to be responsible for the higher incidence of HNSCC observed in the Basque Country.

Global DNA methylation: uncommon event in oral lichenoid disease

OBJECTIVES Accumulating evidence indicates that aberrant DNA methylation is closely related to oral carcinogenesis, and it has been shown that methylation changes might be used as prognostic biomarker in oral squamous cell carcinoma. Oral lichenoid disease (OLD) is the most common oral potentially malignant disorder in our region. The aim of this study was to perform the first wide DNA methylation study in OLD in order to investigate the relevance of DNA methylation changes in this premalignant disorder. MATERIALS AND METHODS Two different Illumina microarray platforms, namely the GoldenGate Cancer Panel I and the HumanMethylation27 DNA Analysis BeadChip, were utilized in the discovery phase to interrogate the methylation profile of 59 OLD cases and 9 healthy individuals. Top-ranked genes were further validated by pyrosequencing in a second sample set consisting of 160 OLD and 65 controls. RESULTS Our results show that the frequency of aberrant DNA methylation is rare in OLD, and this finding was further corroborated by pyrosequencing in the biological validation. CONCLUSIONS These findings reinforce the notion that molecular alterations associated with oral carcinogenesis do not seem to be common events in OLD, which in turn might explain the low rate of malignization of this disorder.

Bone Remodeling around Implants Placed in Augmented Sinuses in Patients with and without History of Periodontitis

BACKGROUND Susceptible individuals may be more prone to bone loss after augmentation procedures. PURPOSE Identify plausible clinical and biological factors influencing apical and marginal bone remodeling at implants placed in augmented sinuses, in patients with and without history of periodontitis. MATERIALS AND METHODS This prospective cross-sectional clinical study analyzed implant bone levels in a group of 104 patients with and without history of periodontitis undergoing 139 sinus augmentation procedures. Marginal and apical bone loss (MBL/ABL) was measured post-loading using a standardized digital technique. Measurements were taken preoperatively, at second stage implant uncovery, one year after loading and at an average of 53-months follow-up. Odds ratios were calculated to evaluate risks factors of contributing variables, such as, smoking, history of periodontitis, membrane perforation, surgical approach, grafting material, use of PRP, and implant design/dimensions. RESULTS Patients with history of periodontitis were 8.43 times more likely to present more than 2mm of MBL than patients without it (p =.041; CI95%: 1.09-65.12). Smokers were 4.97 times more likely to present over 2 mm of MBL than non-smokers (p =.003; CI95%: 1.70-14.54). Sinus membrane perforations were 11.4 times more likely to present ABL than those without perforation (p = 0.007; CI95%: 1.94-66.93). Mean MBL/ABL after 1-year post-loading and at last control were 0.49/0.56 mm and 0.67/0.46 mm, respectively. The use of a collagen membrane to cover the antrostomy and only xenograft as grafting material decreased ABL by 0.9 mm. The combination of autologous/xenograft bone was 4.04 times more likely to present higher ABL than xenograft alone (p = 0.023; CI95%: 1.21-13.45). Overall implant survival/success rates were 94.39%/91.33%, respectively. CONCLUSIONS Smoking and previous history of periodontitis negatively affects implant MBL. Sinus membrane perforation was associated with higher ABL. Lack of association between bone remodeling at marginal and apical areas suggests that they are different and independent processes.

Genomewide miRNA profiling of oral lichenoid disorders and oral squamous cell carcinoma

OBJECTIVE To dissect the aberrant microRNA profile of oral lichenoid disorders (OLD) by analyzing the larger set of OLD samples tested so far. MATERIALS AND METHODS MicroRNA expression profiles were assessed using TLDA card in 32 samples (16 OLD, 8 OSCC, and 8 control). The findings were validated using RT-qPCR in an independent cohort of 91 samples. RESULTS We identified 20 differentially expressed microRNAs in OLD, of which several are functionally related to cell proliferation, response to organic substances, or immune processes. Further validation of the top-ranked microRNAs revealed that they were all aberrantly expressed in OLD. CONCLUSION We have identified a new microRNA signature associated with OLD that may provide a meaningful basis for better understanding the physiopathology of the disease. In addition, we validated seven microRNAs whose expression was shown to be higher in OLD tissue in comparison with the control and OSCC tissues.

Differential expression of snoRNAs in oral squamous cell carcinomas: new potential diagnostic markers

Abstract Background: Small nucleolar RNAs (snoRNAs) are small non-coding RNA sequences whose most studied function is ribosome biogenesis. The altered expression of snoRNA is observed in tumoral processes such as breast cancer and multiple myeloma. However, we have not found any references to snoRNAs in oral squamous cell carcinomas (OSCC) in the literature at the time this article was written. Material and methods: We have analyzed snoRNA expression in frozen OSCC tissue samples and have compared them to healthy controls. RNA was extracted from a total of eight OSCC samples and eight control samples, measuring the differential expression of small RNAs with the Affymetrix® miRNA 4.1 Array Plate microarray platform. Results: Results were analyzed using the Transcriptome Analysis Console 3.0 (TAC) software. We obtained a total of 16 deregulated snoRNAs of which one was over expressed and 15 were under expressed. SnoRNAs expression was altered in OSCC and could serve as a diagnostic marker.

In Vitro Antifungal Susceptibility of Oral Candida Isolates from Patients Suffering from Caries and Chronic Periodontitis

Caries and chronic periodontitis are common oral diseases where a higher Candida colonization is reported. Antifungal agents could be adjuvant drugs for the therapy of both clinical conditions. The aim of the current study has been to evaluate the in vitro activities of conventional and new antifungal drugs against oral Candida isolates from patients suffering from caries and/or chronic periodontitis. In vitro activities of amphotericin B, fluconazole, itraconazole, miconazole, nystatin, posaconazole and voriconazole against 126 oral Candida isolates (75 Candida albicans, 18 Candida parapsilosis, 11 Candida dubliniensis, six Candida guilliermondii, five Candida lipolytica, five Candida glabrata, four Candida tropicalis and two Candida krusei) from 61 patients were tested by the CLSI M27-A3 method. Most antifungal drugs were highly active, and resistance was observed in less than 5% of tested isolates. Miconazole was the most active antifungal drug, being more than 98% of isolates susceptible. Fluconazole, itraconazole, and the new triazoles, posaconazole and voriconazole, were also very active. Miconazole, fluconazole and voriconazole have excellent in vitro activities against all Candida isolates and could represent suitable treatment for a hypothetically adjunctive therapy of caries and chronic periodontitis.

Epidermal growth factor receptor expression in different subtypes of oral lichenoid disease

The oral lichenoid disease (OLD) includes different chronic inflammatory processes such as oral lichen planus (OLP) and oral lichenoid lesions (OLL), both entities with controversial diagnosis and malignant potential. Epidermal growth factor receptor (EFGR) is an important oral carcinogenesis biomarker and overexpressed in several oral potentially malignant disorders. Objectives: To analyze the EGFR expression in the OLD to find differences between OLP and OLL, and to correlate it with the main clinical and pathological features. Material and Methods: Forty-four OLD cases were studied and classified according to their clinical (Group C1: only papular lesions / Group C2: papular and other lesions) and histopathological features (Group HT: OLP-typical / Group HC: OLP-compatible) based in previous published criteria. Standard immunohistochemical identification of EGFR protein was performed. Comparative and descriptive statistical analyses were performed. Results: Thirty-five cases (79.5%) showed EGFR overexpression without significant differences between clinical and histopathological groups (p<0.05). Histological groups showed significant differences in the EGFR expression pattern (p=0.016). Conlusions: All OLD samples showed high EGFR expression. The type of clinical lesion was not related with EGFR expression; however, there are differences in the EGFR expression pattern between histological groups that may be related with a different biological profile and malignant risk. Key words:Oral lichenoid disease, oral lichen planus, oral lichenoid lesion, oral carcinogenesis, EGFR.