Expression of prothymosin in lung cancer is associated with squamous cell carcinoma and smoking

Prothymosin (ProT) is a nuclear protein that serves a role in oncogenesis, by promoting proliferation and inhibiting apoptosis in various malignancies. The present study was designed to investigate ProT expression in resected human non-small cell lung cancer to define the clinicopathological associations of ProT-positive lung cancer. Immunohistochemical staining of ProT was performed using tumor sample slides from 149 patients with non-small cell lung cancer, who underwent surgical resection. Association between the expression of ProT and the following clinicopathological parameters was accessed: Age, sex, stage, lymph node involvement, pathological subtype, recurrence and cigarette smoking. A total of 85 tumors (57%) were classified as ProT-positive lung cancer by staining intensity and 73 tumors (49%) were regarded as ProT-positive by scoring index. The majority of patients with ProT-positive tumors were younger (P=0.05) and had squamous cell carcinoma (P<0.01) compared with older and adenocarcinoma. Positive expression of ProT by staining intensity was associated with a higher incidence rate of cancer recurrence (P=0.05) compared with negative ProT expression. ProT was also associated with cigarette smoking, particularly in the group with squamous cell carcinoma. Therefore, the present data suggested that ProT-positive non-small cell lung cancer was associated with younger patients, squamous cell carcinoma, cigarette smoking and a higher incidence recurrence rate, subsequently indicating a subtype consisting of patients with smoking-associated inferior outcomes.