Xanthatin induces glioma cell apoptosis and inhibits tumor growth via activating endoplasmic reticulum stress-dependent CHOP pathway.

Xanthatin is a natural sesquiterpene lactone purified from Xanthium strumarium L., which has shown prominent antitumor activity against a variety of cancer cells. In the current study, we investigated the effect of xanthatin on the growth of glioma cells in vitro and in vivo, and elucidated the underlying mechanisms. In both rat glioma C6 and human glioma U251 cell lines, xanthatin (1-15 µM) dose-dependently inhibited cell viability without apparent effect on the cell cycle. Furthermore, xanthatin treatment dose-dependently induced glioma cell apoptosis. In nude mice bearing C6 glioma tumor xenografts, administration of xanthatin (10, 20, 40 mg·kg-1·d-1, ip, for 2 weeks) dose-dependently inhibited the tumor growth, but did not affect the body weight. More importantly, xanthatin treatment markedly increased the expression levels of the endoplasmic reticulum (ER) stress-related markers in both the glioma cell lines as well as in C6 xenografts, including glucose-regulated protein 78, C/EBP-homologous protein (CHOP), activating factor 4, activating transcription factor 6, spliced X-box binding protein-1, phosphorylated protein kinase R-like endoplasmic reticulum kinase, and phosphorylated eukaryotic initiation factor 2a. Pretreatment of C6 glioma cells with the ER stress inhibitor 4-phenylbutyric acid (4-PBA, 7 mM) or knockdown of CHOP using small interfering RNA significantly attenuated xanthatin-induced cell apoptosis and increase of proapoptotic caspase-3. These results demonstrate that xanthatin induces glioma cell apoptosis and inhibits tumor growth via activating the ER stress-related unfolded protein response pathway involving CHOP induction. Xanthatin may serve as a promising agent in the treatment of human glioma.

Total glucosides of Danggui Buxue Tang attenuates bleomycin-induced pulmonary fibrosis via inhibition of extracellular matrix remodelling.

OBJECTIVES: This study was designed to investigate the antifibrosis effects and possible mechanism of action of total glucosides of Danggui Buxue Tang (DBTG) on bleomycin-induced pulmonary fibrosis in rats. METHODS: DBTG was extracted from Radix Astragali and Radix Angelicae Sinensis. Pulmonary fibrosis was induced by intratracheal instillation of bleomycin (5 mg/kg) in Wistar rats. Subsequently, the rats received daily intragastric administration of DBTG (16, 32 or 64 mg/kg per day) or cortisone (3 mg/kg) 1 day after bleomycin instillation for 4 weeks. Histological changes in the lung were evaluated by hematoxylin and eosin and Masson's trichrome staining. Markers of fibrosis in serum were determined by radioimmunoassay. The mRNA expression of metalloproteinases 1 and 9 (MMP-1, MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1) in lung tissue were detected by reverse transcription PCR. KEY FINDINGS: DBTG administration attenuated the degree of alveolitis and lung fibrosis, and markedly reduced the elevated levels of hyaluronic acid, laminin, type III procollagen and type IV collagen in serum. DBTG decreased the mRNA levels of MMP-9 and TIMP-1. MMP-1 expression was only moderately decreased by DBTG. CONCLUSIONS: DBTG had an inhibitory effect on bleomycin-induced pulmonary fibrosis and its effect may be associated with the ability of DBTG to inhibit the synthesis of extracellular matrix and balance the MMP/TIMP-1 system.

[Effects of low-level laser irradiation on rat mesenteric microcirculatory disturbance during early stage of endotoxemia].

OBJECTIVE: To observe the effects of low-level laser irradiation on mesenteric microcirculation of rats in vivo in the early stage of endotoxemia (ETM). METHODS: The experimental model of ETM was reproduced by injection of lipopolysaccharide (LPS). Sixty healthy male Sprague-Dawley (SD) rats were divided into three groups used random number table: control group, LPS group and low-level laser irradiation group, each group included 20 rats which were subdivided into four temporal subgroups (1, 2, 4, 6 hours, respectively). In low-level laser irradiation group, the rats were irradiated by type SLT semiconductor laser (650 nm, 5 mW) on unilateral femoral artery and vein, and blood vessel of the ear concurrently for 30 minutes. The interference course was vertical irradiation taken at 30 minutes after the injection of LPS. At 1, 2, 4, 6 hours after the injection of LPS, changes in mesenteric microcirculation and microcirculatory blood flow were recorded with the laser Doppler flowmeter, the velocity of red blood cells in venules was observed, and the number of open capillaries and adherent leukocytes were recorded. RESULTS: The blood flow velocity (mm/s) of the mesenteric microcirculation in LPS group was accelerated at 1 hour and 2 hours after LPS injection (1 hour: 0.190+/-0.007 vs. 0.174+/-0.009, 2 hours: 0.200+/-0.010 vs. 0.172+/-0.015, both P<0.05, respectively), but decelerated at 6 hours (0.116+/-0.015 vs. 0.164+/-0.011, P<0.05). The blood flow volume in the mesenteric vessels and the number of open capillaries did not show any significant change at that time. Significant increase in number of adherent leukocytes was observed at 2, 4, 6 hours after injury (2 hours: 2.60+/-1.14 vs. 0.40+/-0.55, 4 hours: 5.40+/-0.89 vs. 0.40+/-0.55, 6 hours : 5.40+/-1.52 vs. 0.60+/-0.90, all P<0.05, respectively). The state of blood flow in the microcirculation became abnormal. After irradiated with laser in low dose, the blood flow velocity was smooth and stable (mm/s, 1 hour: 0.174+/-0.011, 2 hours: 0.180+/-0.023, 4 hours: 0.168+/-0.013, 6 hours: 0.162+/-0.023), and the number of adherent leukocytes was reduced significantly at 4 hours and 6 hours than that in LPS group (4 hours: 2.00+/-0.71 vs. 5.40+/-0.89, 6 hours: 2.60+/-1.52 vs. 5.40+/-1.52, both P<0.05) and the microcirculatory flow state was improved obviously. CONCLUSION: Low-level laser irradiation may ameliorate the local mesenteric microcirculation, alleviate the microcirculatory disorder in early stage of ETM.