Histone deacetylase inhibitor LBH589 induces apoptosis of multiple myeloma cell line U266 in vitro and its mechanism / 白血病·淋巴瘤

Objective To study the effect of new generation histone deacetylase inhibitor LBH589 single-drug or combined with the mouse serum which contains the radix echinopsis on multiple myeloma (MM) cell line U266 and their mechanism.Methods The acetylation level of α-tublin which was a substrate of HDAC6 was detected by Western blot.The chemical force between Heat shock protein 90 (HSP90) and its client proteins was detected by immune precipitation (IP).Results The different concentrations of LBH589 single drug (0,20,50 nmol/L),and 50 nmol/L combined with the mouse serum which contained the radix echinopsis (1 g/ml) were able to inhibit the proliferation of U266 cell.With the increase of drug concentration and the extension of time,the acetylation levels of α-tublin and HSP90 increased gradually (at 24 or 48 hours) in a dose dependent (P ＜ 0.05).The inhibition of LBH589 combined with the mouse serum was stronger than that of LBH589 single drug (P ＜ 0.05).Conclusion LBH589 could inhibit the growth of MM cells and their cell cycles,and induce the apoptosis of MM cell line U266.

Binding chemistry and molecular heterogeneity of neurotensin binding protein(s)/receptor in adult chicken tissues.

The study focuses on the importance of Tyr11 amino acid (AA) and subsequent stereochemistry involved in the binding process of neurotensin (NT) with its receptor (NTR)/binding protein(s) as well as the size heterogeneity. Using the binding of 125I-NT with several chicken tissues, it is identified that one of the crucial factors behind all high affinity (Kd ~10 pM) interactions is due to phenolic-OH (Φ-OH) at the para (p) position of Tyr11 within RRPYIL-CO2H (NT8-13) sequence. Replacing the p-OH only in Tyr11 by substituting with p-Cl, p-F and p-NH2 results in significant change of the binding affinity (Kd); p-OH ≈ p-NH2 (~10 pM), p-Cl (~100 pM), p-F (~120 pM). Interestingly, p-NH2 equals to p-OH displaying the highest affinity. Experiments conducted by binding several of the 125I-azido–NT analogs having azido group attached at different positions within the NT molecule have further confirmed the necessity of RRPYIL sequence for high affinity ligand-receptor interaction. The role of Tryp11 in place of Tyr11 in addition to the results above establishes a significant possibility of H–bonding occurring between p-OH of NT and NTR inside the docking space. Photo labeling of the liver tissue by substituted 125I-Y3-azido-NT analogs shows several specifically labeled bands with considerable range of molecular weight (Mr ~90-30 kDa) variations. These results indicate the existence of molecular heterogeneity concerning the sizes of NTR or else any NT binding proteins in the avian tissues. Further, the study has revealed that besides liver, several other chicken tissues also express similar specific high affinity binding (Kd ~20 pM) with varying capacities (Bmax). The order for Bmax is: liver (1.2 pMol/mg) gall bladder (1.03 pMol/mg) > spleen (0.43 pMol/mg) > brain (0.3 pMol/mg) > colon lung (0.15 pMol/mg). In all cases, the binding was reduced by GTPgS (ED50 ~ 0.05 nM), NEM (ED50 ~ 0.50 mM) and NaCl (ED50 ~30 mM), indicating the existence of NTR identical to the mammalian type-1.

Argi nase from rat fibrosarcoma. Purification and properties.

Arginase from rat fibrosarcoma was purified about 1900-fold and its properties were compared with those of the enzyme from liver and kidney. Arginase from fibrosarcoma was a neutral protein of molecular weight 120,000 with a Km value of 11 mM for arginine. The activation energy was 7.2 kcal/mol and the pH optimum was 10. The fibrosarcoma enzyme was immunologically different from that of the liver. The arginase from fibrosarcoma closely resembled the arginase from the kidney in its electrophoretic, kinetic and immunological properties.