Clinical significance of BRAFV600E and PD-L1 protein expression in papillary thyroid carcinoma

Abstract:

Objective：To detect the expression of BRAF V600E and PD-L1 in papillary thyroid carcinoma（PTC） and to explore its correlation with clinical features of PTC. Methods：Totally 128 cases of PTC in the First Affiliated Hospital of Chongqing Medical University from the year 2015 to 2017 were randomly collected as the research subjects，and 40 cases of normal thyroid tissue were served as controls. The expression of BRAF V600E and PD-L1 protein was detected using immunohistochemistry. Results：The positive rate of BRAF V600E protein was 67.9%（87/128） in PTC，which was significantly higher than that in normal thyroid tissue（ ?字2=11.693，P=0.000），and it was closely related to the age of patients [more than or equal to 45 years old（ ?字2=22.345，P=0.000）] and thy－roid capsule invasion（ ?字2=4.643，P=0.031）. The positive rate of PD-L1 protein was 57.8%（74/128） in PTC，which was also signifi－cantly higher than that in normal thyroid tissue（ ?字2=9.812，P=0.000），and it was significantly correlated with the age[more than or equal to 45 years old， ?字2=44.390，P=0.000）]，lymph node metastasis（ ?字2=28.584，P=0.000） and thyroid capsule invasion（ ?字2=12.895，P=0.000）. Multiple factors analysis showed that BRAF V600E protein expression was significantly correlated with age≥45（OR=3.003，95%CI=1.218 to 7.404，P=0.017） and thyroid capsule in－vasion（OR=12.341，95%CI=3.944 to 38.620，P=0.000）. PD-L1 protein expression was significantly correlated with age≥45（OR=6.667，95%CI=2.668 to 16.657，P=0.000），lymph node metastasis（OR=3.987，95%CI=1.592 to 9.987，P=0.003） and thyroid capsule invasion（OR=4.249，95%CI=1.447 to 12.478，P=0.008）. Further analysis showed that the PD-L1 expression rate in the PTC patients with positive BARF V600E expression was 75.8%（66/87），which was significantly higher than that in the PTC patients with negative BARF V600E expression 19.5%（8/41）（?资=0.520，P=0.000）. There was a consistency between BRAF protein and PD-L1 protein expression in thyroid papillary carcinoma. Conclusion：This study show immunosuppressive molecule PD-L1 is overexpressed in the PTC patients with positive BARF V600E expression，and the co-overexpression of BRAF V600E and PD-L1 protein in PTC patients is associated with the worse prognosis.