Effect of different concentrations of medroxy-progesterone acetate combined with 17ß-estradiol on endothelial progenitor cells.

OBJECTIVE: Endothelial progenitor cells (EPCs) have the ability to differentiate into mature endothelial cells. Inhibition of EPC proliferation and migration may be a new method for anti-tumor therapy. Medroxyprogesterone acetate (MPA) may act on tumor angiogenesis by impacting biological functions of EPCs. The aim of this work was to study the effect of different concentrations of MPA combined with 17ß-estradiol (17ß-E2) on proliferation, migration, and apoptosis of EPCs in vitro. MATERIALS AND METHODS: Proliferation tests (MTT analysis) and migration assay of EPCs, isolated from bone marrow of canine, were performed to detect their response to different concentrations of MPA combined with 17ß-E2 (1 × 10(-8) mol/L). The growth curves were drawn every 24 h for 7 consecutive days. The cell cycle and apoptosis of EPCs were analyzed by flow cytometry. RESULTS: 17ß-E2 (1 × 10(-8) mol/L) increased EPC proliferation, while lower concentration of MPA (≤ 10(-5) mol/L) partially inhibited it. The higher concentration of MPA (≥ 10(-4) mol/L) combined with 17ß-E2 had a significant inhibitory effect on EPC growth, arresting it in the S phase. It also increased the apoptosis rate and damaged the migration ability of EPCs. CONCLUSIONS: Low concentration of MPA partially inhibited the function of 17ß-E2 that promotes the proliferation of EPCs. However, high concentration of MPA combined with 17ß-E2 inhibited a variety of biological functions of EPCs. So, the MPA has a bidirectional effect combined with 17ß-E2 on the cell biology of EPCs.

Intense nanosecond pulsed electric fields promote cancer cell apoptosis through centrosome-dependent pathway involving reduced level of PLK1.

BACKGROUND: Intense nanosecond pulsed electric fields (nsPEFs) have been known to promote apoptosis without physically changing membrane structure or damaging morphology of tumor cells. To determine the contribution of centrosome to the progression of apoptosis by nsPEFs, HeLa cells were exposed to high intensity (6 kV/cm) nsPEFs (8-32 ns) in normal culture condition and cell biology and molecular parameters of cells were investigated. MATERIALS AND METHODS: Apoptotic cell death was identified by TUNEL assay after being exposed to the nsPEFs with various pulse durations, while immunofluorescent staining was performed to detect the number and distribution of centrosomes. To clarify whether nsPEFs-induced centrosome over-duplication is the consequence of DNA damage, we used comet assay to detect simultaneous DNA damage. And additionally Western Blot was used to detect PLK1 protein level to explore the correlation between apoptotic cell death and nsPEFs-induced centrosome over-duplication. Correlation between nsPEFs and molecular parameters was statistically analyzed. RESULTS: NsPEFs induced a clear apoptosis reaching a maximum at 24ns, 24h after exposure (p < 0.05), where DNA fragmentation and over-duplicated centrosomes were observed. This apoptosis may be promoted in a time- and pulse duration-dependent manner. Polo-like kinase (PLK1) protein levels were significantly decreased by such nsPEFs (p < 0.05). Control treatment without the nsPEFs did not cause any damage to the cultured HeLa cells. CONCLUSIONS: Intense nsPEFs promote cell apoptosis through a centrosome-mediated pathway involving a reduction in the level of PLK1, which may provide new therapeutic targets for human cancer treatment.