Aim and background: The purpose of the study was to investigate the role and clinical implications of autophagy and reactive oxygen species-related proteins in carcinoma of an unknown primary (CUP).
Methods and study design: Tissue microarray was constructed for a total of 77 CUP cases. Immunohistochemical stains conducted were as follows: autophagy-related beclin-1, LC3A, LC3B, and p62; redox-related catalase, thioredoxin reductase, glutathione S-transferase π, thioredoxin-interacting protein, and manganese superoxide dismutase. Immunohistochemical results were then related to their clinicopathologic parameters.
Results: The degree of LC3A expression showed a difference according to histologic subtype. In undifferentiated carcinoma, LC3A had the highest expression and adenocarcinoma had the lowest expression (P = 0.021). According to clinical subtype, there was a significant difference between LC3A and glutathione S-transferase π in expression. LC3A had the highest expression in single-organ types and the lowest in intermediate and carcinomatosis types (P = 0.003). Glutathione S-transferase π showed the highest expression in nodal-type tumors and the lowest in carcinomatosis types (P = 0.010). In univariate analysis, shorter overall survival was related to tumor glutathione S-transferase π negativity (P = 0.030).
Conclusions: Different expression levels of the autophagy and reactive oxygen species-related proteins, LC3A and glutathione S-transferase π, were observed according to histologic and/or clinical subtype of carcinoma of an unknown primary.