Early apoptotic features of K562 cell death induced by 5-aminolaevulinic acid-based photodynamic therapy.

摘要: 5-Aminolaevulinic acid-based photodynamic therapy (ALA-PDT) is used to eliminate cancerous cells through photoactivation of endogenously formed protoporphyrin IX (PPIX) following the administration PPIX precursor, 5-aminolaevulinic acid (ALA). We report on kinetics accumulation and mechanism cytotoxic effects ALA-PDT studied in chronic myelogenous leukaemia derived cell line K562. The distribution and, consequently, were found be heterogenous. A subpopulation K562 accumulating a lesser extent exhibits only transient cycle arrest. fraction cells, probably those with higher accumulation, are irreversibly damaged by ALA-PDT. detected several signs an early apoptosis: lowering Bcl-xL expression, decrease mitochondrial plasma membrane potential, cytochrome c release into cytoplasm, unmasking antigen 7A6. However, late apoptotic events lacking: neither caspase-3 activation nor DNA fragmentation occurred. Instead, rapidly progressing necrosis resulting from damage was observed. suggest that high level antiapoptotic heat-shock proteins HSP70 HSP27 us responsible for inhibition process upstream caspases activation.