TP53 AND C-MYC CO-ALTERATIONS - A HALLMARK OF ORAL CANCER PROGRESSION

Background: Head and neck squamous cell carcinoma, including oral cancer, is the sixth most common cancer worldwide. Despite advances in surgery and treatment, the 5-year survival rate has not improved significantly. There fore, reliable molecular markers for oral cancer progression are badly needed. Methods: We conducted a copy number analysis to estimate amplification status of c-myc, cycD1 and EGFR oncogenes, mutational PCR-SSCP analysis to determine activation of H-ras oncogene and inactivation of TP53 tumour suppressor gene and methylation specific PCR analysis to evaluate hypermethylation of p16 and MGMT genes. Results: c-myc oncogene was amplified in 56.7%, cycD1 in 20% and EGFR in 16.7% of Oral Squamous Cell Carcinoma (OSCC) cases while H-ras was activated in 33.3% of samples. Amplification of c-myc was significantly associated with the tumour grade 2. Interestingly, EGFR and H-ras alterations were mutually exclusive. p16 and MGMT were inactivated by hypermethylation in 30% and 13.3% of cases. Co-alteration of cycD1 and p16 were not observed in any of the analyzed samples. TP53 was inactivated in 56.7% of samples and was significantly associated with progression of OSCC, grade 2 and stage 2. Moreover, TP53 and c-myc oncogene were simultaneously altered in grade 2 OSCC. Conclusions: The most promising marker of OSCC progression remains the TP53 tumour suppressor, which is the most frequently mutated gene in oral cancers. Since there is synergism between TP53 and c-myc, it seems that co-alteration of these two genes could be also a good marker of OSCC progression from grade1 to grade 2 tumours

Somatic Mutation and Polymorphism Analysis in Pleomorphic Adenomas of the Salivary Glands

Background: Genetic studies of salivary gland neoplasms were mainly focused on chromosomal changes, and some specific patterns of chromosome translocations have been described. However, molecular alterations, in particular the role of HER-2/H-ras/c-myc signalling cascade in pleomorphic adenoma pathogenesis (PA), are less well characterized. In addition, data on single nucleotide polymorphisms (SNPs) as potential susceptibility factors for PA development are also quite scarce. Methods: Mutational analyses were performed by means of real-time PCR (HER-2 and c-myc amplification analysis), PCR-SSCP and sequencing (H-ras point mutation detection). Polymorphisms analysis was performed by PCR-RFLP (survivin and MMP-9 genes). Results: Amplification of HER-2 and c-myc has been found in 13% and 9% of PA cases respectively. Point mutations in H-ras codons 12/13 have been detected in 17% of PAs. No correlation could be established between these alterations and clinical characteristics of PAs, whereas they might play a role in a subset of malignant salivary gland tumours. As for survivin -31 G/C polymorphism, C allele carriers had a 4-fold decrease of the risk of developing PA (p=0.05). Carriers of the variant allele T of the -1562C/T SNP in MMP-9 gene had a 4-fold increase of the risk of developing PA (p LT 0.001). Conclusions: A longer follow-up of PA patients harbouring mutations could uncover a prognostic role of HER-2 and c-myc amplification as predictors of adenoma transformation into carcinoma. Both survivin and MMP-9 promoter polymorphisms represent susceptibility factors for the development of PAs in the Serbian population

Roentgencraniometric analysis of the angular craniofacial dimensions in subjects with temporomandibular disorders

Introduction: Anomalies in growth and development of the craniofacial skeleton, particularly of vertical dysplasia, may be accompanied by distinct signs and symptoms of temporomandibular disorders. Vertical dysplasia followed by numerous occlusal disturbances alters muscular activity resulting in non-physiological strain on articular structures and their remodelling. Objective. The purpose of this study was to evaluate a possible assocciation between certain morphologic features of the craniofacial skeleton and the presence of signs and symptoms of temporomandibular disorders in young adults with preserved natural dentition. Method. The investigation was carried out on 30 lateral cephalometric radiographs made of 30 subjects with signs and symptoms of temporomandibular disorders. According to the values of the ANB angle (Steiner cephalometric analysis), all subjects were classified in the skeletal class 1.The control group consisted of 50 lateral cephalometric radiographs made of subjects with the skeletal class 1 without signs and symptoms of temporomandibular disorders. The roentgencraniometric analysis of lateral cephalometric radiographs included the evaluation of 20 angular dimensions. Results. The result of this study points at significant differences between the Bolton standards and the following angular dimensions in subjects with temoromandibular disorders:(S-Na)-Pg, (B-Na)-Pg, (Pns-Ans)-(Go-Gn), Occl-i, (S-Na)-i, (S-Na)-(Go-Me), (Go-Me)-i, SNB. The comparative analysis between the subjects of the experimental and the control group revealed significant differences in the values of the following angular dimensions: OccP-(Go-Po) i (S-N)-(Go-Me) at the level of p lt 0.001. Conclusion. The values of the analyzed angular dimensions in both subjects of the experimental and the control group show significant differences when related to the same angular dimensions in the Bolton standards. This can be explained by specific morphologic features of the craniofacial skeleton in subjects of our population. Small number of significant differences in the values of the examined angular variables between the subjects with signs and symptoms of temporomandibular disorders and subjects without such signs/symptoms can be explained by the fact that the study included young persons with the skeletal class 1 jaw relationships and relatively harmonious relations within the orofacial complex.Uvod: Anomalije u rastu i razvoju kraniofacijalnog skeleta, posebno vertikalne displazije, kao što su skeletno otvoren zagrižaj (sindrom dugog lica), dubok zagrižaj (sindrom kratkog lica) i jednostrano otvoren zagrižaj, mogu biti praćene i određenim znacima, odnosno simptomima temporomandibulnih poremećaja. Smatra se da vertikalne displazije praćene brojnim okluzivnim smetnjama menjaju aktivnost mišića, dovodeći do nefiziološkog opterećenja zglobnih struktura i njihove remodelacije. Cilj rada. Cilj istraživanja je bio da se utvrdi eventualna veza između određenih morfoloških odlika kraniofacijalnog skeleta i znakova i simptoma temporomandibulnih poremećaja kod mladih osoba s očuvanom prirodnom okluzijom. Metod rada. Za potrebe istraživanja načinjeno je 30 profilnih telerendgenograma glave 30 ispitanika sa znacima i simptomima temporomandibulnih poremećaja. Vrednovanjem ugla ANB (kefalometrijska analiza po Štajneru) iz ove serije izabrano je 20 snimaka ispitanika sa znacima, odnosno simptomima temporomandibulnih poremećaja čiji skeletni odnosi odgovaraju prvoj klasi. Kontrolnu grupu za rendgenkraniometrijska istraživanja činilo je 50 profilnih telerendgenograma glave osoba koji pripadaju prvoj skeletnoj klasi i kod kojih nisu utvrđeni znaci i simptomi temporomandibulnih poremećaja. Rendgenkraniometrijska analiza obavljena na svakom profilnom telerendgenogramu obuhvatila je vrednovanje 20 angularnih dimenzija. Rezultati. Rezultati studije su pokazali da postoji statistički značajna razlika između ispitanika sa temporomandibulnim poremećajima i vrednosti sledećih angularnih dimenzija u Boltonovim standardima: (S-Na)-Pg, (B-Na)-Pg, (Pns-Ans)- (Go-Gn), Occl-i, (S-Na)-i, (S-Na)-(Go-Me), (Go-Me)-i, SNB. Komparativnom analizom su utvrđene statistički značajne razlike između eksperimentalne i kontrolne grupe u vrednostima angularnih dimenzija OccP-(Go-Po) i (S-N)-(Go-Me) na nivou verovatnoće od p lt 0,001. Zaključak. Analizirane angularne dimenzije kod ispitanika i eksperimentalne i kontrolne grupe značajno se razlikuju od istih angularnih dimenzija u Boltonovim standardima, što se može objasniti specifičnim morfološkim obeležjima kraniofacijalnog skeleta kod naše populacije. Mali broj značajnih razlika u ispitivanim angularnim dimenzijama između ispitanika sa znacima i simptomima temporomandibulnih poremećaja i i ispitanika bez takvih znakova i simptoma objašnjava se činjenicom da su ispitivanja obavljena na ciljnim grupama mladih ispitanika prve skeletne klase i relativno harmoničnim odnosima u predelu orofacijalnog kompleksa

Genomic instability and tumor-specific DNA alterations in oral leukoplakias

Leukoplakias, clinically identifiable premalignant lesions, often precede oral squamous cell carcinoma (OSCC). Identification of leukoplakias that have the potential for transformation to malignancy is a key clinical problem. The aim of this study was to assess genomic instability, and to detect tumor-specific genomic alterations, in leukoplakias. Genomic instability was analyzed by comparing the DNA fingerprints of 32 leukoplakias with those of paired normal tissue. In addition, the mutational status of the p53 gene was analyzed using polymerase chain reaction-single-stranded conformational polymorphism (PCR-SSCP) and polymerase chain reaction-heteroduplex DNA (PCR-HET), and the mutations were subsequently confirmed by DNA sequencing. Moderate-to-significant genomic instability was detected in all leukoplakias analysed. Nine unique amplicons, present in leukoplakias but not in normal tissue, were retrieved and successfully characterized. The p53 gene was mutated in 40.6% of patients. Four patients with moderate instability and mutated p53 developed OSCC. The data obtained in this study support and concretize the thesis that premalignant lesions possess many of the alterations found in cancer before the development of a malignant phenotype. Inactivation or mutation of the p53 tumor-suppressor might be an early event contributing to genomic instability and increasing the risk of malignant transformation

High frequency of p16 and p14 promoter hypermethylation and marked telomere instability in salivary gland tumors

Objectives: to investigate p16(INK4a) and p14(ARF) tumor suppressor gene methylation status, determine telomere length and assess the importance of these epigenetic and genetic parameters in the development of pleomorphic adenoma and carcinoma ex pleomorphic adenoma of the parotid salivary glands. Materials and Methods: Genomic DNA from paraffin-embedded samples of 50 pleomorphic adenomas and 10 carcinomas ex pleomorphic adenoma was subjected to methylation specific polymerase chain reaction for hypermethylation analyses and real time polymerase chain reaction for the relative telomere length calculations. Results: Promoter hypermethylation of the two genes was a very frequent event in both neoplasms between 60% and 90% of samples were hypermethylated - but without significant difference between the groups. The mean relative telomere length in the pleomorphic adenoma group was significantly increased in comparison to the control group (P = 0.00), and significantly decreased in comparison to the carcinoma group (P = 0.05). Telomeres were also longer in myxoid and cellular histological subtypes of adenomas than in the classic type (P = 0.044 and P = 0.018, respectively). Longer telomeres were more frequent in tumors with hypermethylated p14(ARF) alleles (P = 0.013). Conclusion: Promoter hypermethylations seems to be an important mechanism of p16(INK4a) and Pl4(ARF) inactivation in parotid gland tumors. Telomeric lengthening appears to be involved in the pathogenesis of both benign and malignant tumors of the parotid glands. (C) 2015 Elsevier Ltd. All rights reserved

Incidence and clinical relevance of T(11;19) translocation in salivary gland mucoepidermoid carcinoma

Mucoepidermoid carcinoma (MEC) harbors a recurring t(11;19) translocation with an associated novel fusion oncogene-MECT1-MAML2. The CRTC1-MAML2oncogene disrupts normal cell-cycle and differentiation, contributing to tumor development. The objectives of this study were to establish the incidence of CRTC1-MAML2 fusion in Serbian patients and estimate its relevance as a genetic marker of MEC behavior. In this retrospective study, 20 cases of MEC of salivary glands were tested for the presence of CRTC1-MAML2 fusion using reverse transcriptase-polymerase chain reaction. Clinicopathological parameters and survival data were examined in relation to fusion status. The CRTC1-MAML2 fusion was detected in 40% of MECs and its presence was associated exclusively with low-intermediate grade tumor histology (P = 0.02) and favorable clinical outcome, with 100 % overall survival rate (P=0.046). The study has shown that the presence of the CRTC1-MAML2 fusion can serve as an additional diagnostic and prognostic marker for mucoepidermoid carcinomas