Promoter hypermethylation profile of tumour suppressor genes in oral leukoplakia and oral squamous cell carcinoma

PURPOSE OF THE STUDY

The present study was conducted to evaluate epigenetic alteration of five tumour suppressor genes in the oral precancer and cancer patients.

MATERIALS AND METHODS

The study was carried out in three groups namely control group of five people (normal healthy individuals), 10 oral leukoplakia patients and 10 oral squamous cell carcinoma patients. Incisional biopsy was done and part of the tissue sent for histological examination and part of tissue sent for hypermethylation study of p16, p15, hMLH, MGMT, E-cadherin tumour suppressor genes. Methylation specific polymerase chain reaction was carried out for detecting methylation in promoter regions of tumour suppressor genes. The resultant PCR products were run in a 2.5% agarose gel and the promoter hypermethylation status of the five tumour suppressor genes were analysed.

RESULTS

In oral Leukoplakia patients, 60% of methylation in the case of p16 gene, 30% of methylation in the case of MGMT gene and 60% of methylation in the case of E-cadherin gene. In oral Squamous cell carcinoma patients, 60% of methylation in the case of p16 gene, 40% of methylation in the case of MGMT, 60% of methylation in the case of E-cadherin gene, 20% in case of p15,10% in case of hMLH gene.

CONCLUSION

Our results suggest that epigenetic mechanisms of inactivation of tumour suppressor genes, such as aberrant methylation of p16 and E-cadherin genes occur early in head and neck tumourigenesis and might play a role in the progression of these lesions.

The status of sulphated isomers of glycosaminoglycans in fluorosed human teeth

Fluorosed human teeth have lower concentrations of glycosaminoglycan (GAG) disaccharides and an increased dermatan sulphate content. Teeth from subjects with a high fluoride intake have a higher ratio of 4-sulphated to 6-sulphated GAGs. Increased dermatan sulphate may be an important factor in the clinical manifestations of fluorosis.

Incidence and etiology of midline diastema in a population in south India (Madras)

In a cross-sectional study of midline diastemas in a South Indian (Madras) population, 9,774 patients aged 13-35 years were screened. True midline diastema was defined as one without periodontal/periapical involvement and with the presence of all anterior teeth in the arch. Sample purification resulted in a research sample of 166 patients with true midline diastemas. The incidence of true maxillary midline diastema (160/9774-1.6%) was greater than that of true mandibular midline diastemas (31/9774-0.3%). No direct etiologic factor for the midline diastemas was noted. Spacing in the anterior region was the most significant factor associated with the midline diastema.