[Targeting miR155 restores chemotherapy sensitivity in drug-resistant myeloma cell-line RPMI8226/DOX cells].

Objective: To explore the mechanism of abnormal expression of microRNA155 (miR155) in myeloma drug-resistance to probe the possibility of inhibiting miR155 expression to restore chemotherapy sensitivity and its molecular mechanism in drug-resistant myeloma cells. Methods: Drug-resistant myeloma cell-line RPMI8226/DOX was established by culturing RPMI8226 cells with continuous low concentration and intermittent gradually increasing concentration of doxorubicin in vitro; The levels of miR155 mRNA were measured by qRT-PCR, and both proteins FOXO3a and BCL-2 expressions were detected by Western blot in cell-lines RPMI8226/S and RPMI8226/Dox. RPMI8226/DOX cells were transfected by miR155 inhibitor and mimic using gene transfer method, and then CCK-8 was used to measure proliferation and inhibition ratio, the changes of miR155 expression were detected by RT-PCR. Proteins FOXO3a and BCL-2 were detected by Western blot. Results: Comparing with RPMI8226 cells, the level of miR155 mRNA was obviously up-regulated with the relative expression of 26.860±2.340, together with increased expression of Bcl-2 protein but decreased expression of FOXO3a in RPMI8226/DOX cells. After 72 h treatment with miR155 inhibitor, the inhibition rate of transfection was 64.57%, miR155 expression decreased sharply, the level of FOXO3a expression was upregulated while BCL-2 expression decreased, chemotherapy sensitivity was restored on cell-line RPMI8226/DOX with reversed drug-resistance ratio of 2.518. Conclusions: The abnormal expression of miR155 was closely associated with myeloma drug-resistance, targeting inhibition of miR155 expression could restore chemotherapy sensitivity by increasing FOXO3a expression in drug-resistant myeloma cells.

Ferulic acid induces heme oxygenase-1 via activation of ERK and Nrf2.

This study investigated the effect of ferulic acid (FA) on the up-regulation of heme oxygenase-1 (HO-1) in lymphocytes and the molecular mechanisms involved. Lymphocytes were treated with FA (0.001-0.1 µM) for certain times. Cell viability, the activity and level of expression of HO-1, and signal pathways were analyzed. FA significantly upregulated HO-1 expression both at the level of mRNA and protein in lymphocytes. Moreover, FA induced NF-E2-related factor (Nrf2) nuclear translocation and transcriptional activity, which is upstream of FA induced HO-1 expression. In addition, lymphocytes treated with FA exhibited activation of extracellular regulated kinase (ERK) and treatments with U0126 (an ERK kinase inhibitor) attenuated the FA induced activation of Nrf2, resulting in a decrease in HO-1 expression. Zinc protoporphyrin (ZnPP, a HO-1 inhibitor) markedly suppressed cytoprotection from radiation-induced cell damage by FA. Results suggested that the ERK signaling pathway controlled the anti-oxidation of FA by regulating the expression of the antioxidant enzyme HO-1.

Serum fructose concentration in rats after single dose oral administration of Si-Wu-Tang.

Our previous study showed that fructose is an important active constituent that is responsible for Si-Wu-Tang's (SWT) effects promoting hematopoiesis and immunity. In order to provide primary data for analysis of the mechanism of fructose's bioactivity, the concentration of serum fructose in rats after a single oral administration dose of Si-Wu-Tang was determined. The concentration of serum fructose in fasting rats was 0.34 ± 0.24 mg/dL. After oral administration of 7.2 mL per kg body weight of SWT extract (1 mL extract corresponds to 1 g SWT dried herbs), serum fructose levels reached a peak concentration of 1.03 ± 0.25 mg/dL within 60 min, and then declined to the baseline level within 180 min, a pattern which is similar to the one reported for oral administration of pure fructose. The peak concentration was only 2-3 times higher than the baseline serum fructose concentration. These results showed that the increase of blood fructose concentration after oral administration of SWT is small and transient, which is very probably due to the quick metabolism of fructose by the liver. We suggest, for future research, it is necessary to consider the probability that fructose's bioactivity on hematopoiesis and immunity is not exerted by fructose in its original form, but after it is metabolized by the liver.

Effects of clonidine on myocardial beta-adrenergic receptor-adenyl cyclase-cAMP system after scalds in rats.

AIM: To study the role of clonidine (Clo) on the myocardial beta-adrenergic receptor (beta-AR)-adenyl cyclase (AC)-cAMP system after the scalds in rats. METHODS: A 30% skin-full-thickness scald was produced by immersing rats in 95 degrees C water for 9 s. Clo 0.1-3.0 mg.kg-1 was injected i.p. to rats at 30 min before scalds, yohimbine (Yoh) 0.05 mg.kg-1 or prazosin (Pra) 0.03 mg.kg-1 to rats at 30 min before i.p. Clo. beta-AR density and affinity, AC activity, phosphoric diester hydrolases (PDH) activity, and cAMP content were determined with radioreceptor assay, indirect method, enzymeradiochemical assay, and radioimmunoassay, respectively. RESULTS: Clo inhibited the decrease of the myocardial beta-AR density, the attenuation of AC activity, and the reduction of cAMP content at 12 h after the scalds. Yoh partially reversed the effects of Clo on the three parameters. But Pra did not. CONCLUSION: Clo reversed the changes of the myocardial beta-AR-AC-cAMP system resulted from the scalds in rats.