Betulinic acid induces apoptosis in human chronic myelogenous leukemia (CML) cell line K-562 without altering the levels of Bcr-Abl.
Betulinic acid (BA), a plant derived triterpenoid, isolated from various sources shows cytotoxicity in cell lines of melanoma, neuroectodermal and malignant brain tumors. Chronic myelogenous leukemia (CML) is characterized by Philadelphia chromosome (Bcr-Abl), a molecular abnormality leading to the intrinsic tyrosine kinase activity that provides growth and survival advantage to the cells. Present study describes the cytotoxicity of BA on human CML cell line K-562, positive for Bcr-Abl. The decrease in the viability of K-562 cells treated with BA at different concentrations and time intervals was assessed using MTT assay. Cell death induced by BA was determined to be apoptotic as measured by FACS analysis of PI stained nuclei, PS externalization by Annexin-V fluorescence and characteristic DNA fragmentation. DiOC6(3) fluorescent probe determined alterations in the mitochondrial membrane potential (MMP). RT-PCR confirmed the expression levels of Bcr-Abl in controls and K-562 cells treated with BA. The rapid loss of MMP of K-562 cells upon treatment with BA shows the direct activation of apoptosis at the level of mitochondria, overcoming the resistance of the high levels of expression of Bcr-Abl.
Raghuvar Gopal
D V
DV
Laboratory Nuclear Medicine Section, Isotope Group, BARC, C/o Tata Memorial Hospital Annexe, Jerbai Wadia Road, Parel, Mumbai 400012, India.
Narkar
Archana A
AA
Badrinath
Y
Y
Mishra
K P
KP
Joshi
D S
DS
D017304:Annexin A5; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D004353:Drug Evaluation, Preclinical; D004587:Electrophoresis, Agar Gel; D016650:Fluorescein-5-isothiocyanate; D016044:Fusion Proteins, bcr-abl / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D020128:Inhibitory Concentration 50; D007425:Intracellular Membranes / Q000187:drug effects; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D053978:Pentacyclic Triterpenes; D014315:Triterpenes / Q000494:pharmacology*; D000094062:Betulinic Acid
D017304:Annexin A5; D000972:Antineoplastic Agents, Phytogenic; D053978:Pentacyclic Triterpenes; D014315:Triterpenes; D016044:Fusion Proteins, bcr-abl; D016650:Fluorescein-5-isothiocyanate; D000094062:Betulinic Acid