INTERDEPENDENCE OF EXPRESSION LEVEL OF HIGH MOBILITY GROUP BOX PROTEIN 1 AND TUMOUR SUPPRESSOR PROTEIN p53

Non histone nuclear protein high mobility group B1 (HMGB1) and the tumour suppressor factor p53 interact with each other and regulate various processes such as DNA damage signalling, apoptosis and autophagy. Those findings make HMGB1 protein and p53 important players in tumour development and cancer therapy. In many cancer cells variation in proteins' amounts were registered. Therefore it is important to understand the mechanisms that keep their levels in functional balance. Our aim was to study how the change in the expression level of one protein affects the amount of the other. Non-small lung cancer (NSCLC) lines A549 with functional p53 gene and 111299 that is p53-null were studied as experimental models. We down-or up-regulated the protein synthesis of either HMGB1 or p53 and quantified the expression level of the partner protein. We found that p53 down-regulates HMGB1 and the synthesis of p53 also depends on HMGB1 variations.