Analysis of DNA Glycosylases MUTYH and OGG1 and Their Correlation with EGFR Signalling in Normal and Nodular Thyroid Tissues

07-P05. Analysis of DNA Glycosylases MUTYH and OGG1 and Their Correlation with EGFR Signalling in Normal and Nodular Thyroid Tissues. Introduction: Thyroid diseases affect about 20% of the Italian population. The identification of molecular markers to characterize pre-malignant or malignant thyroid lesions is an important goal in the clinical management of patients affected by thyroid nodules. Many aspects of the nodular pathogenesis remain unclear, although the association among thyroid hormone metabolism, oxidative DNA damage, and the high rate of spontaneous mutations present in the normal thyroid appears to be the basis of carcinogenesis. To verify whether the DNA repair system for oxidative stress injuries was already involved in the early stages of thyroid carcinogenesis, we analysed MUTYH and OGG1 and their relationship with EGFR signalling in normal and nodular thyroid tissues. Methods: Forty-one TIR3B euthyroid nodules and adjacent normal tissues were selected from patients who had undergone thyroid surgery at Unit of Surgical Oncology of SS Annunziata Hospital, Chieti. Gene and protein expression were evaluated by qRTPCR and Western blot, respectively. All statistical analyses were performed using SPSS software. Significance was set at p <0.05. Results: Medical records showed the presence of Ab- Anti-TPO and Anti-TG in 19 out of 41 cases, even if under the cutoff values; thus, we subdivided tissues into goiters without inflammatory features (NIG: n°22) andgoiters with inflammatory features (IG: n°19). In pathological tissues, MUTYH gene expression was significantly higher in IG compared to NIG (p =0.04). ERBB2 gene expression showed a significant difference (p = 0.01) between normal and pathological NIG tissues with an increase in the second ones. A positive correlation between ERBB2 and MUTYH expression was observed both in pathological and normal tissues, with p = 0.023 and p <0.001, respectively. OGG1 expression showed a direct relationship with Anti-TPO in normal tissues (p = 0.008) that reverted in pathological tissues (p = 0.011). OGG1 protein was more expressed in pathological tissues than in normal tissues, whereas ERBB2 and EGFR showed no difference in expression between normal and pathological tissues. Conclusions: The current study provided the first evidence that in thyroid tissues, ERBB2 and MUTYH gene expression were related, and OGG1 protein overexpression could be a marker of thyroid nodular disease.