Objective:To explore the abnormal expression and the clinicopathologic significance of Polo-like kinase 1 (PLK1) in adenocarcinoma (ADC) of the lung. Methods:The expressions of PLK1 in 266 patients with stage I-IV lung ADC were detected by immunohistochemistry (IHC) (SP method). The correlations with PLK1 expression and the clinicopathological characteristics, the expression of TTF1 and p53 and the molecular phenotype were further analyzed. Results:There was a positive correlation with PLK1 overexprssion and smoking history (P<0.05), metastesis/recurrence (P<0.01), and higher stage (P<0.05). PLK1 overexpression was more frequently found in colloid ADCs (87.5%), invasive mucinous ADCs (86.7%) and solid ADCs (81.1%) (P<0.01). PLK1 overexprssion was more common in mucin-product ADCs than in non mucin-product ADCs (P<0.05). PLK1 overexpression was significiantly correlated with KRAS mutation (P<0.01), p53 protein expression (P<0.01) and triple negative ADCs (P<0.01), other than TTF1 expression, EGFR mutation or EML4-ALK fusion. In lung ADCs, PLK1 overexpression was strongly associated with prognosis (P<0.01), and played as an independent prognostic role (HR=2.235, P<0.01). Conclusion:PLK1 overexpression possibly plays an important role in pathogenesis and evolution of a subset of lung ADCs.
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