Effect of Lidamycin on Telomerase Activity in Human Hepatoma BEL-7402 Cells

Objective To investigate the effect of lidamycin （LDM） on telomerase activity in human hepatoma BEL-7402 cells under the condition of LDM inducing mitotic cell death and senescence. Methods Chromatin condensation was detected by co-staining with Hoechst 33342 and PI. Cell multinucleation was observed by Giemsa staining and genomic DNA was separated by agarose gel electrophoresis. Fluorescent intensity of Rho123 was determined for mitochondrial membrane potential. MTT assay and SA-13-gal staining were employed to analyze the senescence-like phenotype. The expression of proteins was analyzed by Western blot. Telomerase activity was assayed by telomerase PCR-ELISA. Results Mitotic cell death occurred in LDM-treated cells characterized by unique and atypical chromatin condensation, multinucleation and increased mitochondrial membrane potential. However, no apoptotic bodies or DNA ladders were found. In addition, apoptosis-related proteins remained nearly unaltered. Senescence-like phenotype was identified by increased and elongated size of cells, growth retardation, enhanced SA-13-gal activity and the changes of senescence-related protein expression. Telomerase activity markedly decreased （P〈0.01） in LDM-treated hepatoma BEL-7402 cells. Conclusion Mitotic cell death and senescence could be triggered simultaneously or sequentially after exposure of hepatoma BEL-7402 cells to LDM. The decrease in telomerase activity may play a key role in the defective mitosis and aging morphology. Further investigation of detailed mechanism is needed.

Role of Prosurvival Molecules in the Action of Lidamycin toward Human Tumor Cells

Objective 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. Methods 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 β-galactosidase （SA-β-gal） staining were used to analyze protein expression and senescence-like phenotype, respectively. Results 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. Conclusions Cellular prosurvival molecules, such as SIRTI, Akt, SOD-1, SOD-2 and other unknown factors can influence the action of lidamycin on human tumor cells.

Laser Device for the Protection of Biological Objects from the Damaging Action of Ionizing Radiation

Laser irradiation device for the protection of biological objects from the action of ionizing radiation to be used in practice has been manufactured （invention patent RU 2 428 228 C2）. Research of the action of y-radiation itself as well as of the combined action of laser devices on survival, weight, skin and the general mitotic index of the bone marrow cells （mitotic index of all nucleus-containing cells of the bone marrow） of C57BL/6 experimental young mice was carried out. The mice were irradiated with ionizing （whole body irradiation） and laser radiation, separately one by one in a special frame device. Laser radiation in the dose 1 mJ/cm^2 irradiated only the back of a mouse, or both the back and the abdomen of mice. In case of combined irradiation of mice, the time interval between two types of irradiation did not exceed 30 min. First, the mice were exposed to y-radiation then to laser radiation. The method of the laser radiation-protection of biological subjects contributes to an increase in the viability of mice, prevents the damages of skin and also increases the mitotic activity of mice bone marrow cells.

Extensive supporting cell proliferation and mitotic hair cell generation by in vivo genetic reprogramming in the neonatal mouse cochlea

Subject Code:H13With the support by the National Natural Science Foundation of China,the research team led by Prof.Li Huawei(李华伟)at the Otorhinolaryngology Department,Affiliated Eye and ENT hospital,State Key Laboratory of Medical Neurobiology of Fudan University,achieved the mitotic hair cell generation through agenetic reprogramming procedure,which was published in the Journal of Neuroscience(2016,36(33):8734—8745).

A Long Type of TBCK Is a Novel Cytoplasmic and Mitotic Apparatus-Associated Protein Likely Suppressing Cell Proliferation

Autoantibodies from patients with various connective tissue diseases have been shown to be specific probes that can detect cellular structures, including centrosome, centromere/kineto- chore, spliceosome, Golgi complex and the rough endoplasmic reticulum （Louvard et al., 1982; Rattner et al., 1998;

How to use progestin in hormone replacement therapy: an animal experiment

Objective To determine whether continuous or cyclic hormone replacement therapy (estrogen and progestogen) is better.Methods One hundred and forty Sprague-Dawley rats were randomly divided into seven groups. The 1st and 2nd groups were normal estrous and ovariectomy (OVX) controls. Treatment of the other groups imitated the clinical regimen (continuous and cyclic) with estradiol valerate (E2V) and medroxy progesterone (MPA) in different ratios of combination. The rats were sacrificed and sections of uterus were stained with HE and histochemical metheds to detect mitosis and proliferating cell nuclear antigen (PCNA), respectively. The mitotic index (MI) and PCNA index were calculated.Results The MI and PCNA index were similar in luminal and glandular cells. Both markers were low in the two control groups. When E2V was given for 1 to 6 days, both the MI and PCNA index increased with duration of treatment. When MPA was added, both markers were reduced to a very low level. In the continuous regimen, both markers decreased as the MPA dosage increased. The ratio of E2V∶MPA=1∶0.5 was enough to suppress markers to a low level similar to that of normal estrous rats. A further increase in the ratio to 1∶1.0 showed no further decrease in PCNA index. In the cyclic regimen, MPA was added for the last 5 days. The mitotic index reached a significantly low level near 0 in all ratios, but the PCNA index in each subgroup was still as high as the positive control, even though the dosage of MPA was increased several times to 1∶8.0. When MPA was added for the last 10 days, the PCNA index at a ratio of 1∶4.0 could be reduced to a low level.Conclusion The results of this study suggest that the continuous regimen was better than the cyclic regimen in postmenopausal hormone replacement therapy (HRT). Progestin should be given for at least 10 days in the cyclic regimen.