Expression of Long Non-Coding RNA-NEAT-1 in Papillary Thyroid Carcinoma in Relation to Immunohistochemical expression of CD8 and PD-L1 as Indicators of Tumor Immune Microenvironment.

OBJECTIVE

Investigation of CD8 and PD-L1 immunohistochemical expression, as indicators of tumor microenvironment in PTC, and their correlation with lncRNA-NEAT1 expression.

METHODS

Quantitative determination of relative expression level of lncRNA-NEAT1 using the real-time PCR (RT-qPCR) and evaluation of CD8 and PD-L1 immunohistochemical expression in 47 specimens of PTC tissue compared to 5 controls of normal thyroid tissue. The results were analyzed for their association with the clinicopathological parameters of the studied cases.

RESULTS

Compared to control specimens, LncRNA-NEAT1 expression levels were considerably higher in PTC cases (p=0.000), and they were also significantly higher in patients with nodal metastases and lymphovascular emboli (LVE) (p=0.003 and 0.002 respectively). There were significant associations between PD-L1 positive expression and extra-thyroid extension (p=0.02), nodal metastasis (p=0.00), and LVE (p=0.00). In contrast, significant associations of increased CD8 expression with Hashimoto's thyroiditis (HT) (p=0.007), absent nodal metastasis (p=0.02), and negative LVE (p=0.01) were detected. There was a significant negative correlation between CD8 and PD-L1 expression levels (p=0.014).

CONCLUSION

LncRNA-NEAT1 and PD-L1 expression levels are associated with more aggressive PTC. In contrast, high CD8 expression is associated with favorable parameters. These findings suggest the possible diagnostic and prognostic role of these biomarkers in PTC.