Progressive elevation of MnSOD and GPX4 expression across the spectrum of pulmonary adenocarcinoma lesions: a digital pathology study.

Abstract

Background: Manganese superoxide dismutase (MnSOD) and glutathione peroxidase 4 (GPX4) are key components of the mitochondrial redox defense system; however, their clinical associations across lung adenocarcinoma spectrum lesions (ASLs) are insufficiently defined.

Methods: We analyzed 67 resected ASLs, comprising 14 preinvasive lesions and 53 invasive adenocarcinomas, from 61 patients who underwent video-assisted thoracoscopic surgery (VATS). Paired nonneoplastic lung tissue adjacent to preinvasive lesions served as normal controls. MnSOD and GPX4 expression levels were assessed through immunohistochemical (IHC) staining, digitized to generate whole slide images (WSIs), and semiquantified using IHC pixelwise H-score (0-300) by employing an ImageJ plugin. The exploratory association of MnSOD and GPX4 expression with clinicopathological variables and overall survival was evaluated.

Results: MnSOD and GPX4 IHC pixelwise H-scores increased stepwise from normal lung tissue to preinvasive lesion and further to invasive adenocarcinoma in parallel with higher T-status category. Exploratory analyses demonstrated that a high MnSOD IHC pixelwise H-score (> 154.5) was associated with higher serum carcinoembryonic antigen (CEA) levels (p = 0.001), higher maximum standardized uptake value (SUVmax) on positron emission tomography (p = 0.041), larger tumor size (p = 0.002), M1 status (p = 0.076), spread through air spaces (STAS, p = 0.036), and pleural invasion (p = 0.019). By contrast, a high GPX4 IHC pixelwise H-score (> 165.9) was associated only with pleural invasion (p = 0.014). An exploratory nonlinear inverse association was observed between MnSOD IHC pixelwise H-scores and serum CEA levels (p = 0.004), with a steeper increase at lower CEA levels and a plateau at approximately 5 ng/mL. A high MnSOD IHC pixelwise H-score (> 154.5) exhibited a borderline association with shorter survival (p = 0.052). M status (p = 0.008) and STAS (p = 0.012) were associated with an increased risk of death in exploratory multivariate analysis.

Conclusions: In this hypothesis-generating study, MnSOD and GPX4 IHC pixelwise H-scores progressively increase across lung ASLs, and MnSOD is associated with clinicopathological features of tumor aggressiveness. IHC pixelwise H-score analysis may be a feasible semiquantitative approach for evaluating protein expression in lung ASLs.