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Image analysis of the expression and relationship of beta catenin and axin 1 proteins in human neuroepithelilal brain tumours

In the present study changes in protein expression of two components of wnt signalling pathway, axin 1 and beta-catenin, were investigated in neuroepithelial brain tumours. Image analysis of immunostained samples revealed the quantity, localization and relationship of proteins in question. For each sample, the intensity of staining in a well-defined area was evaluated. Density was depicted as the intensity of light retained by tissue or tissue transparency and expressed in grey scale pixels and was denoted as light permeability (LP). Mean values for LP for axin in normal brain tissue was 63, and for beta-catenin 150, which enabled us to calculate relative LP increase or decrease of axin and beta-catenin proteins in tumour tissue. Down regulation of axin expression and up regulation of beta-catenin were detected in the analyzed tumours. Comparison of mean values of relative increase of protein axin and beta-catenin shows that they were significantly reversely proportional (P = 0.014). Besides, the highest relative value of axin was measured when the protein was in the cytoplasm and it was accompanied with the lowest quantity of beta-catenin. The lowest relative quantity of axin was measured when the protein was in the nucleus and cytoplasm, and it was accompanied with the highest quantity of beta-catenin. In conclusion we believe that our results are indicative of axin’s nucleo-cytoplasmatic shuttling which may contribute to better understanding of human brain tumours pathophysiological mechanisms.

wnt signalling pathway; neuroepithelial brain tumours; axin 1; beta-catenin

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