Autophagy-Related Proteins’ Immunohistochemical Expression and Their Potential Role as Biomarkers in Thymic Epithelial Tumors

Background: Autophagy, a self-destructive cellular mechanism with a paradoxical nature, plays a part in both tumor suppression and induction by providing cancer cells with metabolic substrates, resulting in cell proliferation and survival. In this study, we aim to investigate the clinical significance of four autophagy pathway components (BECLIN, p62/, LC3b, ATG3) in pathogenetic mechanisms of thymic epithelial tumors (TETs) with possible prognostic importance. Methods: Immunohistochemistry was used to evaluate the cytoplasmic expression of BECLIN, p62, LC3b, and ATG3 in tumor cells of 99 TETs, and possible correlations with clinicopathological parameters were examined. Results: Higher BECLIN and p62 expression was associated with male gender (p = 0.027 and p = 0.014, respectively). B3 thymomas and thymic carcinomas (TCs) displayed higher p62 expression (p = 0.019), while LC3b expression was marginally higher in non-B3/TC TETs (p = 0.098). A positive correlation between higher BECLIN expression and advanced Masaoka–Koga stage was also observed (p = 0.009). ATG3 was not associated with any of the investigated clinicopathological parameters (p > 0.05). There was also no significant correlation between any of the four examined molecules and overall survival or relapse. Conclusions: Our findings indicate autophagy activation in B3/TC and advanced Masaoka–Koga stage cases. Further studies are needed to explore the role of these autophagy related proteins as potential biomarkers and therapeutic targets in TETs.