CD-200 induces apoptosis and inhibits Bcr-Abl signaling in imatinib-resistant chronic myeloid leukemia with T315I mutation

Chronic myeloid leukemia (CML) is characterized by a constitutively active Bcr-Abl tyrosine kinase. Although Imatinib has been proven to be an effective drug against CML, its resistance has been observed with disease relapse due to T315I predominant point mutation. Liriodendron tulipifera L., one of the fastest growing hardwood tree species, exerts antioxidant activity and anti-inflammatory effects. However, its anticancer effect has been minimally reported. In this study, we extracted CD-200 from Liriodendron tulipifera L. and investigated its effect on cell survival or apoptosis in CML cells with Bcr-Abl/T315I (BaF3/T315I) as well as wild-type Bcr-Abl (BaF3/WT). CD-200 inhibited cell proliferation in the BaF3/WT cells, and also in the BaF3/T315I cells with Imatinib resistance. Moreover, it strongly inhibited Bcr-Abl signaling pathways in a dose-dependent manner. Also, it significantly increased the sub-Gj phase and the expression of cleaved PARP and caspase-3, as well as the TUNEL-positive apoptotic cells. In addition, we observed that CD-200 induced apoptosis with a loss of mitochondrial membrane potential by decreasing the expression of Mcl-1 and sur vi vin. Furthermore, CD-200 showed a significant inhibition in tumor growth, compared to Imatinib in BaF3/T315I mouse xenograft models. Taken together, our study demonstrates that CD-200 exhibits apoptosis induction and anti-proliferative effect by blocking the Bcr-Abl signaling pathways in the Bcr-Abl/T315I with resistance to Imatinib. We suggest that CD-200 may be a natural product to target Bcr-Abl and overcome Imatinib resistance in CML patients.