HMGB1 protein is a nuclear non-histone protein which was recently discovered to be released in the extracellular medium as a response to various stimuli and implicated in cancerogenesis and tumour metastasis. High HMGB1 levels were reported in variety of tumour types as hepatocellular carcinoma, breast carcinomas, gastric and colorectal adenocarcinomas. Till now there are no data relating HMGB1 presence to the histological grade or to a particular cell type in tumour population. To address the possible relevance of HMGB1 to the clinical outcome we studied the expression of HMGB1 protein in malignant human tumours, e.g. breast carcinomas, hepatocellular and colorectal carcinomas. We applied the immunohistochemical analysis by using the techniques of "antigen retrieval" for determination of the expression level of HMGB1 in various surgical specimens embedded in paraffin. In all tumour tissues tested the protein level is elevated in comparison with the normal ones. An interesting finding is that in moderately differentiated (better prognosis) carcinomas the localization of the protein is perinuclear while in the low differentiated (bad prognosis) there is a well defined tendency for nonspecific nuclear localization and higher expression of HMGB1.
Key words: HMGB1 protein, antigen retrieval method, immunochistochemistry, human tumours