Indirubin in Vitro Apoptotic Effect Towards Chronic Lymphocytic Leukaemia (CLL) Lineage

Abstract

Abstract Chronic lymphocytic leukemia (CLL) is a chronic condition that usually affects elderly people. The etiology is unknown, however the current hypothesis is that over time the haematopoietic stem cells may acquire mutations that will lead to irregularity in apoptotic mechanism (e.g. BCL2 mutation). Dangui Luhui Wan consist in mix of 11 herbs used by the Chinese Medicine. This herbal compound has proven to have antitumoral activities on various types of cancer cells. A derivate from Dangui Luhui Wan is indirubin-3'-monoxime (I3M). This substance act as selective inhibitor of cyclin-dependent kinases (CDKs) and can induce cell apoptosis. The aim of this study was to test the efficacy of I3M against CLL cells in vitro. We evaluated the expression of apoptotic proteins Bcl2/Bax and CDK1/2 using real-time PCR. Peripheral mononuclear cells (PBMCs) obtained from 14 patients were treated with 20 μM of I3M for 48hrs. After treatment a reduced Bcl-2 expression was noticed. No significant changes were seen for Bax. However, an increased Bax/Bcl-2 ratio was documented, suggesting that mitochondrial pathway is involved in I3M apoptotic-mechanism of action. Interestingly, I3M could inhibit the expression of CDK2, while it does not affect the expression of CDK1. These results indicated that I3M exerts anti-tumor effects through induction apoptosis and inhibition of CDK2. Further studies are now needed to clarify the exact mechanism of action of I3M in CLL and possibly in other tumoral cell lines.