Fig 2: Detection of Gpx-2 protein with immunogold labelling in cells of colon adenocarcinoma tissue. The small electron-dense granules (arrowheads) were found in cancerous cells (A,B) and stromal cells, especially in fibroblast-like cells (C,D). In cancerous cells, the granules indicating the presence of Gpx-2 were detected within the cytoplasm and in this compartment, they were connected with the cisterns of the endoplasmic reticulum (A1,B1—black arrows). In fibroblasts, the localisation of Gpx-2 was connected with the cytoplasm as well. In this case, the gold granules were also detected within the membranous components in the cytoplasm. Moreover, the Gpx-2 in fibroblast cells was also associated with the plasma membrane (C1,D1—black arrows). Some cells also showed granules near the intermediate filament bundles. The scale bars are 1 µm (A1,B1,C,C1,D1) and 2 µm (A,B,D).

Fig 3: The expression of Gpx-2 in colon adenocarcinoma tissue (C–F) and adjacent non-cancerous tissue margins (A,B) is shown in this study with photomicrographs and black arrows. (A,B) Low levels of immunohistochemical reactivity were detected in cells found within the tissue margin of the colonic mucosa of non-pathological specimens. The expression was detected mainly in the base of crypts. In colon adenocarcinoma tissues, expression of Gpx-2 can be classified into two distinct groups, namely low (C,D) and high (E,F). The scale bar is 50 µm (A–F).

Fig 4: The images displayed here show the expression of Gpx-2 in colon adenocarcinoma tissue (C–G) and non-cancerous tissue margins (A,B) through immunofluorescence. A fluorescent signal (red colour signal) of varying intensity was found in cells of non-neoplastic mucosa (A,B)—arrowheads indicate expression in the cytoplasm of non-pathological colonocytes and cancer cells (C–G). In some cancer cells, the expression and fluorescence signal was found in the cytoplasm of the apical parts of the cells, while in others, intense fluorescence was found throughout all cytoplasm (arrowheads) of the cells or in the cell nuclei (arrows). (H) results of ANOVA test showing differences between the intensity of red signal indicating the presence of Gpx-2 among the tested groups; C < L, C < H, L < H—differences in intensity between the groups; C—non-neoplastic colon tissue, L—adenocarcinoma specimens with low expression of Gpx-2, H—adenocarcinoma specimens with high expression of Gpx-2.

Fig 5: Kaplan–Meier curves of univariate analysis data (log-rank test) showing the 5-year survival rate for patients with high versus low Gpx-2 immunohistochemical expression.