ABSTRACT
Allergic asthma is a complex and chronic inflammatory airway disease. Interleukin-17 is a pro-inflammatory cytokine which plays critical role in the pathogenesis of allergic asthma. It has been reported that beta-arrestin2 regulated the development of allergic asthma at a proximal step in the inflammatory cascade. In this study, the influence of beta-arrestin2 on Interleukin-17 production and expression of CD4+ T lymphocytes in a murine asthma model was investigated. Splenic CD4+ T lymphocytes from wild-type mice and those from a murine asthma model were purified. CD4+ T lymphocytes from a murine asthma model were transfected with siRNAs targeting the beta-arrestin2 or were pretreated with the ERK1/2 inhibitor, PD98059. After stimulation, the protein expression of beta-arrestin2 phosphorylated-ERK1/2 and IL-17 were detection by Western blot; the mRNA expression of IL-17 were detected by real-time PCR; the accumulation of IL-17 in supernatants were detected by ELISA. We found that beta-arrestin2 phosphorylated-ERK1/2 and IL-17 expression in CD4+ T lymphocytes from a murine asthma model was increased compared with those from wildtype mice[p<0.01]. Treatment of CD4+ T lymphocytes with siRNAs targeting the beta-arrestin2 down-regulated phosphorylated- ERK 1/2 and IL-17 expression [p < 0.01]. PD98059 decreased IL-17 production and expression in CD4+ T lymphocytes in a murine asthma model [p < 0.05]. We conclude that beta-arrestin2 stimulated IL-17 production and expression of CD4+ T lymphocytes in a murine asthma model. The effect was partly mediated by ERK 1/2 activation. Targeting beta-arrestin2 biological activity could be a valid therapeutic approach for the treatment of allergic asthma
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effects and related mechanisms of Tumstatin 185-191 as a single agent or in combination with cisplatin on proliferation and apoptosis in a cisplatin-resistant human lung adenocarcinoma cell line A549-DDP cells.</p><p><b>METHODS</b>A549-DDP cells were treated with Tumstatin185-191 and cisplatin at varying concentrations. Cell viability was assessed by a modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. 50% inhibiting concentration (IC(50)) values of the chemotherapeutic drugs were analyzed by MTT assay. Cell apoptosis was measured by flow cytometry. The activation of Akt and ERK was evaluated by Western blotting.</p><p><b>RESULTS</b>Tumstatin185-191 inhibited the proliferation of A549-DDP cells and its IC(50) value was 80.25 micromol/L. After cotreatment with 20 micromol/L Tum185-191, the IC(50) value of cisplatin in A549-DDP cells reduced from 77.16 micromol/L to 57.97 micromol/L, the reverse index was 1.33, while with 40 micromol/L Tumstatin185-191 the IC(50) was reduced from 77.16 to 26.40 micromol/L and the reverse index was 2.92. The early apoptosis rate was 19.5% +/- 1.1% in the cotreatment group, while 13.3% +/- 1.5% in cisplatin group and 10.2% +/- 2.0% in Tum185-191 group (F = 4.09, P < 0.05). The levels of phospho-Akt (p-Akt) and phospho-ERK (p-ERK) in the A549-DDP cells were remarkably lower after treatment with Tumstatin 185-191. The Tumstatin 185-191 treatment alone or in combination with cisplatin had a similar effect on the protein levels of p-Akt and p-ERK in A549-DDP cells.</p><p><b>CONCLUSION</b>Our data suggest that Tumstatin185-191 may promote apoptosis, downregulate proliferation and partly reverse the drug resistance of A549-DDP cells to cisplatin. The effects induced by Tum185-191 may be mediated through inactivation of the Akt and ERK pathways.</p>