Expression Of Autophagy-related Markers Beclin-1 And P62 In NSCLC And Its Clinical Implications

Objective:To observe the expression of autophagy-related markers Beclin-1 and p62 in NSCLC cell lines and tissues. To investigate the relationship among Beclin-1 and p62 expression with clinicopathological variables of patients and explore the value of Beclin-1 and p62 as prognosis biomarkers of NSCLC.Methods:1. Western-blot analysis and cell immunofluorescence method were used to observe the expression of Beclin-1 and p62 in three human NSCLC cell lines A549, H1299 and HCC827.2. A total of 128 NSCLC specimens were collected from patients who accepted surgical resection at the department of Chest Surgery, the Second Affiliated Hospital of Soohow University from October 2006 to December 2009. All the tissues were formalin-fixed and paraffin embedded, and the tissue microarray(TMA) was made. Immunohistochemistry staining was performed on the TMA to study the expression and distribution of Beclin-1 and p62 in 128 cases of NSCLC tissues.3. The correlation between the expression of Beclin-1 and p62 in NSCLC tissues and the clinicopathological variables of patients were analyzed. The relationship among Beclin-1 and p62 expression with patient overall survival(OS) were explored.Results:1. The expression of Beclin-1 and p62 were detected in all the three NSCLC cell lines on the protein level. The immunofluorescence staining demonstrated that Beclin-1 and p62 were primarily distributed in the cytoplasm of the cells.2. Immunoreactivity of Beclin-1 and p62 were detected mainly in the cytoplasm. High expression of Beclin-1 and p62 were detected in 42.31%(44 of 104) and 49.03%(51 of 104) of the NSCLC tissues, respectively. Furthermore, Beclin-1 expression was negatively correlated with p62(P=0.001). High expression of Beclin-1 was correlated significantly with sex(P=0.007), smoking status(P=0.035), differentiation(P=0.01) and lymph node metastasis(P=0.000). Also, Significant difference was found among p62 expression with TNM stage(P=0.029)and lymph node metastasis(P=0.011). There was no correlation between Beclin-1 and p62 expression with other clinicopathological variables(P>0.05).3. Univariate Cox regression analysis revealed that low expression of Beclin-1 and high expression of p62 were significantly associated with shorter survival(all P<0.001). Moreover, history of COPD and high TNM stage were also related to inferior OS(P=0.014, P=0.000, respectively). Multivariate Cox regression analysis showed that low expression of Beclin-1, high expression of p62 and high TNM stage were independent risk factors related to shorter overall survival for patients with NSCLC(P=0.037, P<0.001, P=0.000).Conclusion:1. Autophagy-related markers Beclin-1 and p62 were mainly detected in the cytoplasm of NSCLC cells. Beclin-1 expression was negatively correlated with p62.2. High expression of Beclin-1 was detected mainly in male and patients with heavy smoking, indicating that autophagy may be initiated by smoke-induced lung inflammation. Beclin-1 expression was also related to differentiation and lymph node metastasis, prompting that Beclin-1 is closely related to the development of NSCLC. p62 accumulation was correlated with high TNM stage and positive lymph node metastasis, also indicating that p62 may be involved in tumor progression.3. Beclin-1 and p62 can be served as valuable independent prognostic markers in NSCLC, and regulating activities of autophagy may be a new target of tumor therapy, which will have a promising application in the future.