Characteristics of mitotic cell death induced by enediyne antibiotic lidamycin in human epithelial tumor cells.
ABSTRACT Mitotic cell death, a different cell death mode from apoptosis, has been focused on in tumor therapy. It may involve the mechanism of highly potent cytotoxicities of enediyne antibiotics toward tumor cells. We describe the characteristics of mitotic cell death induced by enediyne antibiotic lidamycin at low concentrations (0.01-1 nM), in the human hepatoma BEL-7402 cells and human breast carcinoma MCF-7 cells. The cells exerting mitotic cell death showed retardation at G2+M phase, enlargement of cell volume and multinucleation, some of which were positive in senescence-associate beta-galactosidase staining. The multinucleated living cells did not show apoptotic features by co-staining with mitochondria-specific dye Mitosensor and DNA-specific dye Hoechst 33342. The DNA polyploidy rather than increased with incubation time for the lidamycin-treated BEL-7402 cells. The proliferation status of BEL-7402 cells was shown by flow cytometry after the cells were labeled with PKH-67, a fluorescent dye for labeling living cells, but the fluorescent intensity of the lidamycin-treated cells was little changed. The smear DNA pattern was detected in the multinucleated cells by agarose gel electrophoresis. The results provide the first evidence for elucidating the potent cytotoxicities of lidamycin toward tumor cells and further describing characteristics of mitotic cell death.
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ABSTRACT: To investigate the effects of lidamycin (LDM) on a mouse myeloma cell line (SP2/0) and human multiple myeloma cell lines (U266 and SKO-007), and provide the basis for the use of LDM in cancer therapy. A 3-[4,5-dimethylthiazol-2-yl]5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]2H-tetrazolium inner salt (MTS) assay was used to determine the degree of growth inhibition by the drugs analyzed in this study. Cell cycle distribution and analysis were measured by flow cytometry combined with propidium iodide (PI) staining. The effects on apoptosis were measured by Hoechst 33342 staining and by flow cytometry combined with fluorescein-isothiocyanate-Annexin V/propidium iodide (FITC-Annexin V/PI) staining. Protein expression was determined by Western blot analysis. In vivo antitumor activity was measured using a murine myeloma model in BALB/c mice. There was a significant reduction in cell proliferation after treatment with LDM. The overall growth inhibition correlated with increased apoptotic cell death. LDM-induced cell apoptosis was associated with the activation of c-Jun-N-terminal kinase (JNK), and cleavage of caspase-3/7 and poly (ADP-ribose) polymerase (PARP). LDM markedly suppressed tumor growth in a murine myeloma model. LDM induces apoptosis in murine myeloma SP2/0 cells as well as in human myeloma U266 and SKO-007 cell lines. The sustained activation of JNK might play a critical role in LDM-induced apoptosis in the SP2/0 cell line. LDM demonstrates significant antitumor efficacy against myeloma SP2/0 cells in mice. Taken together, our data provide some clues for further research of the effects of LDM on human multiple myeloma.Acta Pharmacologica Sinica (2009) 30: 1025-1032; doi: 10.1038/aps.2009.75.Acta Pharmacologica Sinica 08/2009; 30(7):1025-32. · 2.35 Impact Factor
Article: Podocyte mitosis - a catastrophe.[show abstract] [hide abstract]
ABSTRACT: Podocyte loss plays a key role in the progression of glomerular disorders towards glomerulosclerosis and chronic kidney disease. Podocytes form unique cytoplasmic extensions, foot processes, which attach to the outer surface of the glomerular basement membrane and interdigitate with neighboring podocytes to form the slit diaphragm. Maintaining these sophisticated structural elements requires an intricate actin cytoskeleton. Genetic, mechanic, and immunologic or toxic forms of podocyte injury can cause podocyte loss, which causes glomerular filtration barrier dysfunction, leading to proteinuria. Cell migration and cell division are two processes that require a rearrangement of the actin cytoskeleton; this rearrangement would disrupt the podocyte foot processes, therefore, podocytes have a limited capacity to divide or migrate. Indeed, all cells need to rearrange their actin cytoskeleton to assemble a correct mitotic spindle and to complete mitosis. Podocytes, even when being forced to bypass cell cycle check points to initiate DNA synthesis and chromosome segregation, cannot complete cytokinesis. Such aneuploid podocytes rapidly detach and die, a process referred to as mitotic catastrophe. Thus, detached or dead podocytes cannot be adequately replaced by the proliferation of adjacent podocytes. However, even glomerular disorders with severe podocyte injury can undergo regression and remission, suggesting alternative mechanisms to compensate for podocyte loss, such as podocyte hypertrophy or podocyte regeneration from resident renal progenitor cells. Together, mitosis of the terminal differentiated podocyte rather accelerates podocyte loss and therefore glomerulosclerosis. Finding ways to enhance podocyte regeneration from other sources remains a challenge goal to improve the treatment of chronic kidney disease in the future.Current Molecular Medicine 11/2012; · 4.20 Impact Factor
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ABSTRACT: Lidamycin, an enediyne antibiotic, leads to apoptosis and mitotic cell death of human tumor cells at high and low concentrations. The reason why tumor cells have distinct responses to lidamycin remains elusive. This study was to elucidate if cellular prosurvival molecules are involved in these responses. Cleavage of chromatin and DNA was observed by chromatin condensation and agarose gel electrophoresis. Accumulation of rhodamine 123 in lidamycin-treated cells was assayed by flow cytometry. Cell multinucleation was detected by staining with Hoechst 33342. Western blot and senescence-associated beta-galactosidase (SA-beta-gal) staining were used to analyze protein expression and senescence-like phenotype, respectively. SIRT1 deacetylase remained unchanged in 0.5 nmol/L lidamycin whereas cleavage occurred when apoptosis was induced by lidamycin. Increased FOXO3a, SOD-1 and SOD-2 expression and transient phosphorylation of ERK were detected after exposure of human hepatoma BEL-7402 cells to 0.5 nmol/L lidamycin. High expressions of SIRT1 and Akt were found in colon carcinoma HCT116 p53 knock-out cells exposed to lidamycin. Degradation of PARP and p53 by lidamycin as a substitute for SIRT1 and Akt was confirmed with caspase inhibitor Q-VD-OPh and proteasome inhibitor MG132. Resistance to lidamycin-induced DNA cleavage was observed in breast cancer doxorubicin-resistant MCF-7 cells. This was not induced by P-glycoprotein as no accumulation of rhodamine 123 was detected in the resistant cells following exposure to lidamycin. In contrast to sensitive MCF-7 cells, a lower multinucleation rate for the resistant cells was measured following exposure to equal concentrations of lidamycin. Cellular prosurvival molecules, such as SIRT1, Akt, SOD-1, SOD-2 and other unknown factors can influence the action of lidamycin on human tumor cells.Biomedical and Environmental Sciences 07/2009; 22(3):244-52. · 1.15 Impact Factor