Smurf1-positive expression indicates favorable survival for resected non-small cell lung cancer patients

Recently studies have found that Smurf1 inhibits PIPKIγ-promoted lung cancer cell growth, tumorigenesis, and drug resistance through mediating the ubiquitination and degradation of PIPKIγi2. However, at present there is no study focused on the expression of Smurf1 protein as well as correlations among Smurf1 and lung cancer patients' survival. Therefore, we appraised Smurf1 expression by immmunohistochemistry and analyzed associations with prognosis in resected non-small cell lung cancer (NSCLC) patients. Overall, a number of 175 patients were enrolled in our study. We found that about 53 (30.2%) out of 175 NSCLC patients had Smurf1-pisitive expression. Smurf1-positive expression was significantly associated with lower lymph node metastasis (P=0.012). Smurf1-positive NSCLC patients had more favorable 5-year survival than patients with Smurf1-negative expression by univariate analysis (P=0.0002). Subgroup analysis found the same trend in lung adenocarcinoma (ADC, P=0.0006) other than lung squamous cell carcinoma (SCC, P=0.205). More interestingly, multivariate analysis also suggested that Smurf1-positive expression was significantly related to better overall survival (OS, P=0.003), independent of clinicopathological features and treatments of NSCLC patients. Unfortunately, we failed to observe statistically significant results when analyzed correlations among Smurf1 and NSCLC patients' progression-free survival (PFS, P=0.059). However, subgroup analysis revealed that Smurf1-positive patients had more favorable PFS for lung ADC patients (P=0.011) other than lung SCC (P=0.754). From the above, we guess that Smurf1 should be closely related to tumor metastasis and serve as an independent predictor of favorable prognosis in resected NSCLC patients.