[Expression of vasodilator-stimulated phosphoprotein relates to prostate cancer metastasis].

OBJECTIVE: To investigate the relationship of the expression of vasodilator-stimulated phosphoprotein (VASP) with the metastasis and prognosis of prostate cancer. METHODS: Prostate cancer PC3 cells were infected with VASP shRNA and control shRNA lentiviruses, respectively. The invasive ability of the PC3 cells was determined by transwell migration assay, the expression of VASP in the prostate cancer tissue from 56 patients was detected by immunohistochemistry, and the survival rate of the patients was analyzed according to the VASP expression levels and follow-up data after radical prostatectomy. RESULTS: VASP shRNA lentivirus significantly inhibited the expression of VASP and decreased the invasive ability of the PC3 cells as compared with the results obtained in the scramble shRNA and blank control groups (P<0.05). The survival analysis of the 56 prostate cancer patients showed that the time of biochemical recurrence was markedly shorter in the VASP positive and strongly positive groups than in the VASP-negative cases (P<0.05), but with no statistically significant difference between the former two groups (P>0.05). CONCLUSIONS: VASP is involved in the regulation of the invasive ability of prostate cancer PC3 cells, and the differences in the VASP expression are related to the prognosis of prostate cancer.

Astragalus polysaccharide stimulates glucose uptake in L6 myotubes through AMPK activation and AS160/TBC1D4 phosphorylation.

AIM: To establish the mechanism responsible for the stimulation of glucose uptake by Astragalus polysaccharide (APS), extracted from Astragalus membranaceus Bunge, in L6 myotubes in vitro. METHODS: APS-stimulated glucose uptake in L6 myotubes was measured using the 2-deoxy-[(3)H]-D-glucose method. The adenine nucleotide contents in the cells were measured by HPLC. The phosphorylation of AMP-activated protein kinase (AMPK) and Akt substrate of 160 kDa (AS160) was examined using Western blot analysis. The cells transfected with 4P mutant AS160 (AS160-4P) were constructed using gene transfer approach. RESULTS: Treatment of L6 myotubes with APS (100-1600 µg/mL) significantly increased glucose uptake in time- and concentration-dependent manners. The maximal glucose uptake was reached in the cells treated with APS (400 µg/mL) for 36 h. The APS-stimulated glucose uptake was significantly attenuated by pretreatment with Compound C, a selective AMPK inhibitor or in the cells overexpressing AS160-4P. Treatment of L6 myotubes with APS strongly promoted the activation of AMPK. We further demonstrated that either Ca(2+)/calmodulin-dependent protein kinase kinase ß (CaMKKß) or liver kinase B1 (LKB1) mediated APS-induced activation of AMPK in L6 myotubes, and the increased cellular AMP: ATP ratio was also involved. Treatment of L6 myotubes with APS robustly enhanced the phosphorylation of AS160, which was significantly attenuated by pretreatment with Compound C. CONCLUSION: Our results demonstrate that APS stimulates glucose uptake in L6 myotubes through the AMP-AMPK-AS160 pathway, which may contribute to its hypoglycemic effect.

Structural and functional alterations of two multidomain oxidoreductases induced by guanidine hydrochloride.

The unfolding and refolding of two multidomain oxidoreductases, bovine liver catalase and flavoprotein bovine milk xanthine oxidase (XO), have been analyzed by fluorescence spectroscopy, circular dichroism, and activity measurements. Two intermediates, a partially folded active dimer disassembled from the native tetramer and a partially folded inactivated monomer, are found to exist in the conformational changes of catalase induced by guanidine hydrochloride (GdnHCl). Similarly, two intermediates, an active, compacted intermediate bound by flavin adenine dinucleotide (FAD) partially and an inactive flexible intermediate with FAD completely dissociated, exist in the conformational changes of XO induced by GdnHCl. The activity regains completely and an enhancement in activity compared with the native catalase or native XO is observed by dilution of catalase or XO incubated with GdnHCl at concentrations not >0.5 or 1.8 M into the refolding buffer, but the yield of reactivation for catalase or XO is zero when the concentration of GdnHCl is >1.5 or 3.0 M. The addition of FAD provides a remarkable protection against the inactivation of XO by GdnHCl under mild denaturing conditions, and the conformational change of XO is irreversible after FAD has been removed in the presence of a strong denaturing agent. These findings provide impetus for exploring the influences of cofactors such as FAD on the structure-function relationship of xanthine oxidoreductases.