Immunohistochemical detection of 8-hydroxydeoxyguanosine: A biomarker of oxidative DNA damage in oral submucous fibrosis.

Background: Oral submucous fibrosis (OSMF) is one of the common potentially malignant disorders prevailing in India. The primary etiological factors include tobacco and arecanut, which contain numerous reactive oxygen species (ROS). ROS attack guanine bases in DNA and form 8-hydroxydeoxyguanosine (8-OHdG), which can be detected in patients who have diseases associated with oxidative stress. The oxidative DNA damage produced by oxidative stress may induce malignant transformation.

Aim: The aim of the present study is to detect the expression of 8-OHdG in OSMF patients and compare the expression within different grades of OSMF and also normal buccal mucosa.

Materials And Methods: A total of 30 samples were examined for the immunohistochemical expression of 8-OHdG. The control group included 10 formalin-fixed paraffin-embedded tissue blocks of the normal buccal mucosa. The study group includes 20 cases of formalin-fixed paraffin-embedded tissue blocks of OSMF (5 cases in each grade of very early, early, moderately advanced and advanced cases of OSMF). Three-micron thick tissue sections were made from each sample and stained with 8-OHdG antibody. The results were statistically analyzed using Kruskal-Wallis and Mann-Whitney U test.

Results: Statistically significant difference exists in the intensity of 8-OHdG expression between the study groups. The P-value obtained was <0.001, which was highly statistically significant.

Conclusion: The present study is the first attempt to evaluate the expression of 8-OHdG in tissue samples of OSMF that revealed the role of free radicals and oxidative DNA damage in these patients. Further research with larger sample size, clinicopathologic correlation and long-term follow-up will shed more light on the pathogenesis of OSMF. It will also be useful for the development of new therapeutic strategies targeting treatment modalities for OSMF.