ABSTRACT
Aim To study the effects of difluoromethy-lornithine (DFMO)on cardiomyocytes hypertrophy and apoptosis induced by isoproterenol (ISO).Methods The cardiomyocytes were divided into four groups ran-domly:Control group,ISO group,ISO+DFMO group and (ISO +DFMO +Putrescine)group.The hyper-trophic model of cardiomyocytes was induced by ISO, the cardiomyocytes were pretreated with 0.5 mmol · L-1 DFMO and 0.5 mmol·L-1 putrine,the gene ex-pression of ANP,the surface area of cardiomyocytes and the contents of LDH and MDA were measured. Apoptotic value of cardiomyocytes was observed by An-nexin V/PI,the gene and protein expressions of Bcl-2 and Bax were detected by real-time PCR and Western blot.Results Compared with ISO group,the cell sur-face area,the gene level of ANP,the apoptosis value of cardiomyocytes and the contents of LDH and MDA were decreased in ISO +DFMO group (P <0.05 ). Meanwhile,DFMO pretreatment upregulated the gene and protein expressions of Bcl-2 (P <0.05 ), in-creased the ratio of Bcl-2/Bax (P<0.05 ),downregu-lated the gene and protein levels of Bax (P<0.05 ). Conclusion The cardiomyocyte hypertrophy and ap-optosis induced by ISO can be protected by DFMO pre-treatment,which may be associated with the expression of apoptotic gene Bcl-2 and Bax.
ABSTRACT
PURPOSE: Growth factors stimulate protein phosphorylation resulting in transmission of mitogenic signals. In breast cancer, protein kinases and their substrate proteins are importnat in cell proliferation and phathogenesis. Polymine is known as a mediator of stimuli-induced proliferation in many cell systems. In the present study, we report the importance of polyamines in protein phosphorylation in MCF-7 human breast cancer cells. MATERIALS AND METGODS: Protein phosphorylation study was done by incubating cells in the DMEM containing [gamma-(32)P]-ATP. Quantitation of phosphorylation was analysed by fluorescene image analyzer. Tyrosine phosphorylation was detected by anti-phosphotyrosine antibody. Shc was detected by radioimmunoprecipitation and Western blotting. RESULTS: E2, TGF-alpha, and EGF enhanced the protein phosphorylation in very similar pattern. Among those proteins, 67 kDa protein was most strongly phosphorylated. But the most prominent tyrosine phosphoprotein was 52 kDa protein. DFMO at 5 mM strongly inhibited the phosphorylation of the most proteins. Externally added polyamine could recover the inhibitory effect of DFMO in protein phosphorylation. Among the 5 major tyrosine phosphoproteins, 52 and 46 kDa proteins appeared to be Shc proteins. CONCLUSION: Polyamines modulate signal transduction in relation with estrogen receptor and EGF receptor through multiple steps of protein phosphorylations. Tyrosine phosphorylation of Shc proteins were most significantly influenced by polyamines in growth factor-stimulate breast cancer cell proliferation.
Subject(s)
Humans , Blotting, Western , Breast Neoplasms , Breast , Cell Proliferation , Eflornithine , Epidermal Growth Factor , Estrogens , Intercellular Signaling Peptides and Proteins , MCF-7 Cells , Phosphoproteins , Phosphorylation , Polyamines , Protein Kinases , ErbB Receptors , Signal Transduction , Transforming Growth Factor alpha , TyrosineABSTRACT
Objective: To investigate the effects of DFMO on the growth characteristics, apoptosis and activity of telomerase of K562 cells. Methods: The growth rate, phase distribution of cell cycle and apoptosis of treated cells with DFMO were detected by cell count, morphological assay, FCM analysis and DNA electrophoresis, respectively. The telomerase activity was examined by telomeric repeat amplification protocol(TRAP). Results: In K562 cells treated with DFMO, the growth rate was markedly retarded. The increase in G1 -phase cells and decrease in s-phase population and induction of apoptosis were observed. The activity of telomerase of treated cells was inhibited. Conclusion: The growth inhibition and apoptosis induction of K562 cells treated by DFMO were associated with suppressed telomerase activity. It is suggested that inactivation of telomerase in cancer cells conld be one of important events in antitumor molecular mechanism of inhibition of polyamine biosynthesis.
ABSTRACT
Anopheles Stephensi,infected with Plasmodium yoelii.was fed on 10% sucrose solution containing 1%.difluoromethylornothine(DFMO)to induce the degeneration of its oocysts.On the 11th day after infection,the effects of hemocytes on the normal and degenerated oocysts were observed wtih transmission electron microscopy.In the control group.no hemacytes could be found around the normally-developed oocysts except those degenerated ones.In the DFMO group,all the oocysts underwent degeneration in various degrees and some of them were melanized.All the oocysts were attached by one or more hemocytes which belonged to the category of granulo-cytes morphologically.There were many granules with microtubular construction in the cytoplasm of the hemocytes and in the spaces between a hemocyte and an oocyst.The findings indicate that the degeneration of oocysts can exert a taxic effect on hemocytes and the latter may release the granules and possibly other substances to result in the encapsulation and melanization of the oocysts.