Apoptotic pathways as targets for therapeutic intervention

Mechanism of chlorogenic acid treatment on femoral head necrosis and its protection of osteoblasts

The aim of the present study was to investigate the therapeutic effect of chlorogenic acid on hormonal femoral head necrosis and its protection of osteoblasts. The study established a femoral head necrosis model in Wistar rats using Escherichia coli endotoxin and prednisolone acetate. The rats were divided into five groups and were treated with different concentrations of chlorogenic acid (1, 10 and 20 mg/kg). The main detected indicators were the blood rheology, bone mineral density, and the hydroxyproline and hexosamine (HOM) contents. At a cellular level, osteoblasts were cultured and treated by drug-containing serum. Subsequently, cell proliferation and the osteoblast cycle were measured using flow cytometry, and the protein expression levels of Bax and B-cell lymphoma 2 (Bcl-2) were detected using western blotting. Chlorogenic acid at a concentration of 20 mg/kg (high-dose) enhanced the bone mineral density of the femoral head and femoral neck following ischemia. Simultaneously, blood flow following the injection of prednisolone acetate was significantly improved, and the HOM contents of the high-dose chlorogenic acid group were significantly different. The results from the flow cytometry analysis indicated that chlorogenic acid can efficiently ameliorate hormone-induced necrosis. The osteoblasts were isolated and cultured. The MTT colorimetric assay showed that chlorogenic acid at different densities can increase the proliferation capabilities of osteoblasts and accelerate the transition process of G₀/G₁ phase to S phase, as well as enhance mitosis and the regeneration of osteoblasts. Western blotting detection indicated that chlorogenic acid may prohibit the decrease of Bcl-2 and the increase of Bax during apoptosis, thereby inhibiting osteoblast apoptosis and preventing the deterioration of femoral head necrosis. In conclusion, chlorogenic acid at the density of 20 mg/kg is effective in the treatment of hormonal femoral head necrosis, which may be applicable for future treatment.

Novel, Broad Spectrum Anti-Cancer Agents Containing the Tricyclic 5:7:5-Fused Diimidazodiazepine Ring System

Synthesis of a series of novel, broad-spectrum anti-cancer agents containing the tricyclic 5:7:5-fused diimidazo[4,5-d:4',5'-f][1,3]diazepine ring system is reported. Compounds 1, 2, 8, 11, and 12 in the series show promising in vitro antitumor activity with low micromolar IC(50)'s against prostate, lung, breast, and ovarian cancer cell lines. Some notions about structure-activity relationships and a possible mechanism of biological activity are presented. Also presented are preliminary in vivo toxicity studies of 1 using SCID mice.

Effect of hypoxia-inducible factor-1alpha on transcription of survivin in non-small cell lung cancer

Background

Survivin is a structurally and functionally unique member of the inhibitor of apoptosis protein (IAP) family. It plays an important role, not only in regulating mitosis but also in inhibiting apoptosis. The current literature contains few reports on the transcriptional regulation of survivin expression in lung cancer.

Methods

In this study, we investigated the effect of hypoxia-inducible factor-1α (HIF-1α) on the transcriptional activity of the survivin promoter in non-small cell lung cancer (NSCLC). Immunohistochemical staining was used to detect the expression of survivin and HIF-1α in the lung tissue of 120 patients with non-small cell lung cancer (NSCLC) and 40 patients with benign pulmonary disease. We also performed experiments with the lung adenocarcinoma cell line A549 cells, which were cultured under hypoxic conditions. The expression of survivin and HIF-1α was detected by real-time RT-PCR and Western blotting. In the survivin promoter the putative binding-site for HIF-1α, is -19 bp~-16 bp upstream of TSS. We performed site-directed mutagenesis of this binding site, and used luciferase reporter plasmids to determine the relative activity of the survivin promoter in A549 cells. We also studied the effect of HIF-1α on the expression of survivin by dsRNA targeting of HIF-1α mRNA.

Results

HIF-1α (58.33%) and survivin (81.60%) were both over-expressed in NSCLC and their expressions correlated with one another. They were also expressed in A549 cells under normal and hypoxic conditions, with a significant increase under hypoxic conditions. Site directed mutagenesis of the putative binding site for HIF-1α in the survivin promoter significantly decreased the activity of the survivin promoter in A549 cells. Inhibition of HIF-1α by RNAi decreased the expression of survivin in A549 cell lines.

Conclusion

Our results indicate that the binding of HIF-1α to the survivin promoter increases transcription of the survivin gene. Thus, HIF-1α is an important transcriptional regulator of survivin expression