ИСТИНА

In this study, we revealed cell cannibalism in A431, MCF7 and HaCaT, proved, that one cell is situated inside another, hypothesized, how the cell penetration occurs, saw to the fate of internalized cell and found out the possibility of heterotypic cell cannibalism between normal and neoplastic cells of epithelial origin. Up today a lot of types of the cell death are known, and the most examined among them is apoptosis. Recently the scientists’ attention has been attracted by nonapoptotic kind of cell death – cell cannibalism (CC) – when one cell penetrates into another one and dies inside it. Until now CC has been researched only between cells of one culture (entosis) or between neoplastic cells and specialized cells of immune system (emperipolesis). The aim of this study was to investigate features of the CC and possibility of heterotypic CC in the normal and neoplastic cell lines of epithelial origin. Cell engulfment was observed in A431 (human epidermoid carcinoma), MCF7 (human mammary adenocarcinoma) and HaCaT (normal human keratinocytes). Cells were analyzed by the methods of light, fluorescence, confocal, transmission electron and scanning electron microscopy. We observed that in A431 adhesive junctions were required for CC. Actin and microtubule cytoskeleton provided the penetration of one cell into another. It was proved by treatment of the cells with cytochalasin B and nocodazole. To analyse whether the cells of different cultures penetrate into each other, we cocultivated A431 and HaCaT, A431 and MCF7. Each of these cell lines displayed CC. A431 penetrated into HaCaT considerably more often than into MCF7. In addition, homotypic CC was revealed under cocultivating of different cell lines and it dominated. So, cells of the different types may have similar mechanisms of the recognition and penetration. However, our results have shown that epithelial cells of different organs or tumors may contain some particularities in adhesive or recognition molecules. We can conclude that adherent junctions, actin and microtubule cytoskeleton provide the penetration of one cell into another one. Heterotypic as well as homotypic CC in normal and neoplastic cell lines of epithelial origin are possible, but apparently they may differ in some features.