The polyamine oxidase inhibitor MDL-72,527 selectively induces apoptosis of transformed hematopoietic cells through lysosomotropic effects

• Published in: Cancer research (Chicago, Ill.) Vol. 59; no. 19; pp. 4944 - 4954
• Main Authors: HAIQING DAI, KRAMER, D. L, CHUNYING YANG, MURTI, K. G, PORTER, C. W, CLEVELAND, J. L
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01.10.1999
• Subjects: Animals; Antineoplastic agents; Apoptosis - drug effects; bcl-X Protein; Biological and medical sciences; Cell Cycle - drug effects; Cell Death - drug effects; Cell Line, Transformed; Cell Survival - drug effects; Cell Transformation, Neoplastic; Chemotherapy; Eflornithine - pharmacology; Hematopoietic Stem Cells - cytology; Hematopoietic Stem Cells - drug effects; Hematopoietic Stem Cells - physiology; Humans; Interleukin-3 - pharmacology; Kinetics; Lysosomes - drug effects; Lysosomes - physiology; Lysosomes - ultrastructure; Medical sciences; Mice; Oxidoreductases Acting on CH-NH Group Donors - antagonists & inhibitors; Pharmacology. Drug treatments; Polyamine Oxidase; Polyamines - metabolism; Proto-Oncogene Proteins c-bcl-2 - genetics; Putrescine - analogs & derivatives; Putrescine - metabolism; Putrescine - pharmacology; Spermidine - analogs & derivatives; Spermidine - metabolism; Spermine - metabolism; Antineoplastic agent; Polyamine oxidase; Gene product; Transformed cell; Leukemia; Lysosome; Hematopoietic cell; Cytotoxicity; Lyases; Putrescine; Carboxy-lyases; Spermidine; Established cell line; Mechanism of action; Tumor cell; Human; Enzyme; Enzyme inhibitor; Malignant hemopathy; Ornithine decarboxylase; Gene expression; In vitro; Biological activity; Carbon-carbon lyases; Animal; Oxidoreductases; Apoptosis
• ISSN: 0008-5472; 1538-7445

Polyamine oxidase functions in the polyamine catabolic pathway, converting N1-acetyl-spermidine and -spermine into putrescine (Put) and spermidine (Spd), respectively, thereby facilitating homeostasis of intracellular polyamine pools. Inhibition of polyamine oxidase in hematopoietic cells by a specific inhibitor, N,N'-bis(2,3-butadienyl)-1,4-butanediamine (MDL-72,527), reduces the levels of Put and Spd and induces the accumulation of N1-acetylated Spd. Although previously thought to be relatively nontoxic, we now report that this inhibitor overrides survival factors to induce cell death of several immortal and malignant murine and human hematopoietic cells, but not of primary myeloid progenitors. Cells treated with MDL-72,527 displayed biochemical changes typical of apoptosis, and cell death was associated with the down-regulation of the antiapoptotic protein Bcl-X(L). However, enforced overexpression of Bcl-X(L), or treatment with the universal caspase inhibitor zVAD-fmk, failed to block MDL-72,527-induced apoptosis in these hematopoietic cells. Despite decreases in Put and Spd pools, MDL-72,527-induced apoptosis was not blocked by cotreatment with exogenous Put or Spd, nor was it influenced by overexpression or inhibition of the polyamine biosynthetic enzyme ornithine decarboxylase. Significantly, MDL-72,527-induced apoptosis was associated with the rapid formation of numerous lysosomally derived vacuoles. Malignant leukemia cells were variably sensitive to the lysosomotropic effects of MDL-72,527, yet pretreatment with the ornithine decarboxylase inhibitor L-alpha-difluoromethylornithine sensitized all of these leukemia cells to the deleterious effects of the inhibitor by stimulating its intracellular accumulation. The lysosomotropic nature of select polyamine analogues may, thus, provide a novel chemotherapeutic strategy to selectively induce apoptosis of malignant hematopoietic cells.