Realgar-induced apoptosis and differentiation in all-trans retinoic acid (ATRA)-sensitive NB4 and ATRA-resistant MR2 cells

Realgar has been used in Western medicine and Chinese traditional medicine since ancient times, and its promising anticancer activity has attracted much attention in recent years, especially for acute promyelocytic leukemia (APL). However, the therapeutic action of realgar treatment for APL remains to be fully elucidated. Cellular cytotoxicity, proliferation, apoptosis and differentiation were comprehensively investigated in realgar-treated cell lines derived from PML-RARα+ APL patient, including the all-trans retinoic acid (ATRA)-sensitive NB4 and ATRA-resistant MR2 cell lines. For analysis of key regulators of apoptosis and differentiation, gene expression profiles were performed in NB4 cells. Realgar was found to induce apoptosis and differentiation in both cell lines, and these effects were exerted simultaneously. Gene expression profiles indicated that genes influenced by realgar treatment were involved in the modulation of signal transduction, translation, transcription, metabolism and the immune response. Given its low toxicity, realgar is a promising alternative reagent for the therapy of APL. Our data contribute to an understanding of the underlying mechanism responsible for the therapeutic effects of realgar in the clinical treatment of APL.