Restin protein expression in non-small cell lung cancer

Abstract

Background: Restin is a member of the melanoma-associated antigen (MAGE) superfamily. Its expression has been reported to be up- or downregulated in cancer. Preclinical data suggest it is a tumor suppressor. In this study, we aimed to evaluate restin expression and prognostic value in non-small cell lung cancer (NSCLC).

Methods: Restin expression was analyzed by immunohistochemistry in three tissue microarrays consisting of formalin-fixed/paraffin-embedded NSCLC specimens from 113 patients, represented in triplicate. Restin staining H-score was the result of the staining intensity (0-no, 1-weak, 2-moderate, and 3-strong) multiplied by the percentage of stained tumor cells; it was defined as low if 1-100, moderate if 101-200, and strong if 201-300. Haverage-score was the average H-score in the triplicate. Restin Haverage-scores were tested for correlations with clinical and pathological characteristics and patient outcome.

Results: Restin expression was localized to the cytoplasm, with nuclear enhancement, of 112/113 (99.1%) NSCLCs. Restin Haverage-scores were 0 in 1/113 (0.88%), low in 15/113 (13.3%), moderate in 48/113 (42.5%), and strong in 49/113 (43.4%) NSCLCs. Restin Haverage-scores did not correlate with NSCLC histological subtype, disease stage, recurrence/progression-free, or overall survival.

Conclusion: Restin is moderately to strongly expressed in the majority of NSCLC tumors but its expression has no prognostic value in patients with NSCLC.

Keywords: NSCLC; expression; immunohistochemistry; prognosis; restin.

FIGURE 1

Restin expression evaluated by immunohistochemistry in 113 non‐small‐cell lung cancer (NSCLC) tissues. (a) Global view of three tissue microarrays (TMAs) consisting of NSCLC tissues coming from 113 patients and incubated with an antibody against restin (PA5‐13166). Scale bars: 5000 μm. (b–e) Representative images of NSCLC tumors with: (b) absent, (c) weak, (d) moderate, and (e) strong restin staining scores. Image magnification: 63x and 100x. Scale bars: 50 and 20 μm. Restin displayed a cytoplasmic staining, with nuclear enhancement (restin staining appears red, while tar spots appear brown).

FIGURE 2

Kaplan–Meier curves of overall survival (left panel) and recurrence/progression‐free survival (right panel) according to restin staining Haverage‐score (average H‐score in the triplicate of NSCLC tissues for each patient). Red lines: restin staining Haverage‐score <200. Blue lines: restin staining Haverage‐score ≥200. p, p‐value of the log‐rank test.

FIGURE 3

Receiver operating curves (ROC) curves measuring the added value of the restin staining Haverage‐score in predicting overall survival (OS) and recurrence/progression‐free survival (R/PFS). Time‐dependent ROC curves at 1, 3, and 5 years. Three Cox proportional hazard models were used to predict OS or R/PFS: 1/Model 1, in red: a model based on restin staining Haverage‐score only (<200 vs. ≥200), 2/Model 2, in green: a model based on age (≤60 vs. >60 year‐old), sex, smoking status (current vs. other), and disease stage (I–III vs. IV), and 3/ Model 3, in blue: a complete model including the five previous variables.