Papillary thyroid carcinoma (PTC) is the most common type of thyroid carcinoma.
To investigate the clinical significance of programmed death ligand 1 (PD-L1) and phosphoinositide-dependent protein kinase 1 (PDK1) in PTC.
A total of 194 PTC patients were recruited. Contralateral normal thyroid tissues were obtained and used as controls (n = 80). The expression levels of PD-L1, PDK1 and p-Akt were determined using immunohistochemistry.
The PD-L1, PDK1 and p-Akt were upregulated in cancer tissues compared to the normal tissues. The mean optical density (MOD) values of PD-L1, PDK1 and p-Akt were significantly higher in the PTC tissues. The expression of PD-L1 positively correlated with the levels of PDK1 and p-Akt. In addition, the expression of PD-L1, PDK1 and p-Akt in PTC patients without chronic lymphocytic thyroiditis (CLT) was significantly higher than the expression of those proteins in the CLT patients. The patients with higher expression levels of PD-L1, PDK1 or p-Akt had remarkably larger tumors and higher rates of TNM III-IV, capsular infiltration, lymph node metastasis, and of recurrence. The Kaplan-Meier curve showed that patients with lower expression of PD-L1, PDK1 or p-Akt had significantly longer recurrence-free time. The logistic regression analysis revealed that only CLT, PD-L and capsular infiltration were risk factors for patients’ five-year recurrence.
The PD-L1, PDK1 and p-Akt were found to be positively correlated with a poor prognosis in PTC.