Semi-Quantitative Method of Immunohistochemical Evaluation of the PDCD4 Regulatory Protein to Study its Role in Carcinogenesis

The participation of PDCD4 protein in molecular mechanisms of key importance in carcinogenesis makes the assessment of the level of its synthesis in tissues important for assessing the early diagnosis of malignant tumors. The aim of the presented study was to develop a method for evaluation of the results of immunohistochemical staining of the PDCD4 protein. Material and methods. The material for the study included 49 samples of human gastric adenocarcinoma tissue and 80 cases of endoscopic biopsy examination of the gastric mucosa of patients with dyspeptic complaints. Morphological changes in biopsies corresponded to chronic gastritis with varying degrees of inflammation. Rabbit monoclonal anti-PDCD4 antibodies (clone EP 102, abcam, USA) and a detection system (Diagnostic BioSystems, USA) were used to detect PDCD4 protein by immunohistochemical method. Results. The developed can be used for semi-quantitative visual assessment of synthesis of regulatory protein PDCD4 in histological sections of tissue by immunohistochemical method with detection in nucleus and cytoplasma. That is ensured by calculating an expression index of PDCD4 in tissues when summing up the nuclei expression and cytoplasm expression. Nuclear expression represents a product of staining frequency of nuclei (0–3 points) and semi-quantitative visual assessment of intensity of coloring nuclei (0–3 points). Cytoplasmic expression represents semi-quantitative visual assessment of intensity of cytoplasm (0–3 points). Conclusion. The proposed method makes it possible to evaluate the synthesis of the PDCD4 regulatory protein in tissues with greater sensitivity and specificity, which makes it possible to detect a violation of PDCD4 expression in epithelial cells at the early stages of tumor cell transformation.

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