GMZ27 is a new organic arsenic derivative with anti-leukemic activity, via the induction of reactive oxygen species through NADPH oxidase and mitochondrial pathway that lead to leukemia cell apoptosis

Arsenic trioxide (ATO) is an inorganic arsenic derivative that is very effective against relapsed acute promyelocytic leukemia. It is being investigated as therapy for other cancers, but the risk/benefit ratio is questionable due to significant side effects. In contrast, organic arsenic derivatives (OAD) are known to be much less toxic than ATO. Based on high activity, we selected GMZ27 (dipropil-s-glycerol arsenic) for further study and have confirmed its potent activity against human acute leukemia cell lines. This anti-leukemic activity is significantly higher than that of ATO. Both in vivo and in vitro tests have shown that GMZ27 is significantly less toxic to normal bone marrow mononuclear cells and normal mice. Therefore, further study of the biological activity of GMZ27 was undertaken. ^ GMZ27, in contrast to ATO, can only marginally induce maturation of leukemic cells. GMZ27 has no effect on cell cycle. The anti-leukemic activity of GMZ27 against acute myeolocytic leukemia cells is not dependent upon degradation of PML-RARα fusion protein. GMZ27 causes dissipation of mitochondrial transmembrane potential, cleavage of caspase 9, caspase 3 activation. Further studies indicated that GMZ27 induces intracellular reactive oxygen species (ROS) production, and modification of intracellular ROS levels had profound effect on its potential to inhibit proliferation of leukemic cells. Therefore ROS production plays a major role in the anti-leukemic activity of GMZ27. ^ To identify how GMZ27 induces ROS, our studies focused on mitochondria and NADPH oxidase. The results indicated that the source of ROS generation induced by GMZ27 is dose dependent. At the low dose (0.3 uM) GMZ27 induces NADPH oxidase activity that leads to late ROS production, while at the high dose (2.0 uM) mitochondria function is disrupted and early ROS production is induced leading to dramatic cell apoptosis. Therefore, late, ROS production can be detected in mitochondria are depleted Rho-0 cells. Our work not only delineates a major biologic pathway for the anti-leukemic activity of GMZ27, but also discusses possible ways of enhancing the effect by the co-application of NADPH oxidase activator. Further study of this interaction may lead to achieving better therapeutic index.^

Molecular mechanisms of apoptosis induction in chronic lymphocytic leukemia

CLL is the most common adult leukemia in the Western World, yet very little is known about the biology of this disease. CLL cells have very high levels of NF-κB activity. Factors such as CD40 ligation and phorbol ester treatment induce NF-κB activity and also prevent apoptosis. Previous data from our laboratory demonstrated that MG-132, a proteasome inhibitor, blocked NF-κB activation and promoted apoptosis in CLL cells. These data suggested to us that NF-κB mediates survival in CLL. We examined NF-κB activity using two different chemotherapeutic agents, PS-341 and arsenic trioxide. PS-341, a proteasome inhibitor blocked NF-κB in CLL cells. This however, did not correlate with cell death. Resistant patient isolates displayed delayed Smac/DIABLO release in comparison to cytochrome c release. This suggests that IAPs are contributing to CLL cell survival and drug-resistance. Arsenic trioxide did not block NF-κB activity at therapeutic doses. However it was a potent inducer of apoptosis in CLL cells. We identified a novel mechanism by which arsenic induces increases in mitochondrial calcium to induce cytochrome c release and initiate apoptosis. Both PS-341 and arsenic trioxide are currently in Phase II clinical trials at M.D. Anderson Cancer Center. We conclude that NF-κB is not critical for PS-341 or arsenic trioxide-mediated cell death. ^

William Osler: Original Papers 1881-1897

Part 1: 1881-1888 On Some Points in the Etiology and Pathology of Ulcerative Endocarditis, 1881 On Certain Parasites in the Blood of the Frog, 1883 The Third Corpuscle of the Blood, 1883 On the Use of Arsenic in Certain Forms of Anaemia, 1886 Antifebrin, 1887 Case of Arterio-Venous Aneurism of the Axillary Artery and Vein of Fourteen Year's Duration, 1887 Typhilitis and Appendicitis, 1888 Part 2: 1889-1892 Annual Address - License to Practice 1889 Case of Syphiloma of the Cord of the Cauda Equina-Death From Diffuse Central Myelitis, 1889 On a Case of Simple Idiopathic Muscular Atrophy, Involving the Face and the Scapulo-Humeral Muscles, 1889 Note on Intra-Thoracic Growths Developing from the Thyroid Gland, 1889 On the Value of Laveran's Organisms in the Diagnosis of Malaria, 1889 On the Form of Convulsive Tic Associated with Corprolalia, Etc., 1890 A Case of Sensory Aphasia Word-blindness with Hemianopsia, 1891 Rudolf Virchow: The Man and the Student, 1891 The Healing of Tuberculosis, 1892 The Cold-Bath Treatment of Typhoid Fever, 1892 Part 3: 1893 Remarks on the Varieties of Chronic Chorea, and a Report Upon Two Families of the Hereditary Form, With One Autopsy, 1893 Note on Arsenical Neuritis Following the use of Fowler's Solution, 1893 Note on a Remarkable House Epidemic of Typhoid Fever, 1893 Cases of Sub-Phrenic Abscess, 1893 On Sporadic Cretinism in America, 1893 Notes on Tuberculosis in Children, 1893 Part 4: 1849-1895 Parotitis in Pneumonia, Case of Pericarditis Treated by Incision and Drainage, 1894 The Army Surgeon, 1894 Introductory Remarks to Course of Clinical Demonstrations on Typhoid Fever, 1894 Cancer of the Stomach with Very Rapid Course, 1895 Case of Sporadic Cretinism (Infantile Myxcedema) Treated Successfully with Thyroid Extract, 1895 Visible Contractile Tumour of the Pylorus Following Ulcer of the Stomach, 1895 On the Association of Enormous Heart Hypertrophy, Chronic Proliferative Peritonitis, and Recurring Ascites, with Adherent Pericardium, 1895 Teaching and Thinking the Two Functions of a Medical School, 1895 The Practical Value of Laveran's Discoveries, 1895 Part 5 1896 Addison's Disease, 1896 On Six Cases of Addison's Disease, 1896 Hemiplegia in Typhoid Fever Thomas Dover (of Dover's Powder) Physician and Buccaneer, 1896 John Keats The Apothecary Poet, 1896 On The Classification of the Tics or Habit Movements, 1896 The Cerebral Complication of Raynaud's Disease, 1896 Part 6: 1897 On Certain Features in the Prognosis of Pneumonia, 1897 Clinical Lecture on Mitral Stenosis - Sudden Death - Ball Thrombus in the Left Auricle, 1897 The Diagnosis of Malarial Fever, 1897 The Functions of a State Faculty (President's Address), 1897 A Clinical Lecture on The Ball-Valve Gall-Stone in the Common Duct, 1897 Pneumonia (Review of Cases studied), 1897 Internal Medicine as a Vocation, 1897 Back Notes