Immunohistochemistry and clinical value of sirtuin 2 in non-metastasized non-small cell lung cancer.

Background: This study aimed to define whether sirtuin 2 (SIRT2) expression levels are related to the prognosis of non-small cell lung cancer (NSCLC) patients. Methods: A survival analysis was carried out using the Kaplan-Meier (KM) plotter database. Immunohistochemical staining was performed and KM's method was used to estimate the survival rates for SIRT2 expression in 72 clinical samples. Results: A survival analysis of 1,926 NSCLC patients showed that patients with low SIRT2 expression levels had significantly longer overall survival (OS) than those with high SIRT2 expression levels (P=0.0077; HR =1.19). In 72 non-metastasized NSCLC tissues, the positive rate of SIRT2 expression was 90.3% (65/72), among which, the positive expression rates of squamous cell carcinoma (SCC) and adenocarcinoma (ADC) were 96.4% (27/28) and 85.4% (35/41), respectively. Survival analysis showed that patients with low SIRT2 expression levels had significantly longer median survival time (MST) than those with high SIRT2 expression levels (15.0 versus 14.0 months, P=0.029). Furthermore, the results of subgroup analysis demonstrated patients with low SIRT2 expression levels had significantly longer survival time in ADC group (15.0 versus 12.0 months, P=0.022), but there wasn't significant difference in SCC group (15.0 versus 14.0 months, P=0.932). A multivariate Cox proportional hazards model, which included gender, age, TNM stage, differentiation and SIRT2 expression, showed that SIRT2 expression was an independent factor related to prognosis [HR =1.903, 95% confidence interval (95% CI): 1.085-3.339, P=0.025]. Conclusions: SIRT2 expression levels were significantly related to the survival time of patients with lung ADC but not SCC. Our study indicated SIRT2 was perhaps a specific prognostic biomarker for non-metastasized lung ADC.