Down-regulation of Hsp90 could change cell cycle distribution and increase drug sensitivity of tumor cells

:AIM To construct Hsp90 antisense RNAeukaryotic expression vector, transfect it intoSGC7901 and SGC7901/VCR of MDR-type humangastric cancer cell lines, HCC7402 of humanhepatic cancer and Eel09 of human esophagealcancer cell lines, and to study the cell cycledistribution of the gene transected cells andtheir response to chemotherapeutic drugs.METHODS A I .03kb cDNA sequence of Hsp90Pwas obtained from the primary plasmid phHsp90by EcoR 1 and BamH I nuclease digestion andwas cloned to the EcoR 1 and BamH 1 site ofthe pcDNA by T4DNA ligase and an antisenseorientation of Hsp900 expression vector wasconstructed. The constructs were transfectedwith lipofectamine and positive clones wereselected with G418. The expression of RNA wasdetermined with dot blotting and RNaseprotection assay, and the expression of Hsp90protein determined with Western blot. Cell cycledistribution of the transfectants was analyzedwith flow cytometry, and the drug sensitivity ofthe transfectants to adriamycin (ADR ),vincrinstine (VCR ), mitomycin (MMC ) andcyclophosphamide (CTX ) with MTT andintracellular drug concentration of thetransfectants was determined with flowcytometry.RESULTS In EcoR 1 and BamH I restrictionanalysis, the size and the direction of the clonedsequence of Hsp900 remained what had beendesigned and the gene constructs were namedpcDNA-Hsp90. AH^SGC7901, AH^SGC7901/ VCR,AH-HCC7402 and AH-Eel09 cell clones allexpressed Hsp90 anti--sense RNA. Theexpression of Hsp90 was down--regulated in AHSGC7901, AH--SGC7901/ VCR, AH-HCC7402 andAH--Eel09 cell clones. Cell cycle distribution waschanged differently. In AH-SGC7901/ VCR andAH-Ec109 cells, G, phase cells were increased; Sphase and G, phase cells were decreased ascompared with their parental cell lines. In AHSGC7901 cell, G, phase cells were decreased, Qphase cells increased and S phase cells were notchanged, and in AH-HCC7402 cells G,, S and qphase cells remained unchanged as comparedwith their parental cell lines. The sensitivity ofAH--SGC7901, AH--SGC7901/ VCR, AH-HCC7402 andAH-Ec109 to chemotherapeutic drugs, thesensitivity ot AH--SGC7901/ VCR to ADR, VCR,MMC and CTX the sensitivity of AH-HCC7402 toADR and VCR, and the sensitivity of Eel09 toADR, VCR and CTX all increased as comparedwith their parental cell lines. The meanfluorescence intensity of ADR in AH--SGC7901,AH-SGC7901/ VCR, AH--HCC7402 and AH-Ec109was also significantly elevated (P< 0. 05).CONCLUSION Down-regulation of HsP90 couldchange cell cycle distribution and increase thedrug sensitivity of tumor cells.

Influence of cycle time distribution on coating uniformity of particles in a spray fluidized bed by using CFD-DEM simulations

Cycle Time Distribution(CTD)plays a critical role for determining uniformity of particle coating in spray fluidized beds.However,the CTD is influenced by both geometrical structure and operating conditions of fluidized bed.In this study,a spray fluidized bed of coating process is simulated by a comprehensive Computational Fluid Dynamics-Discrete Element Model(CFD-DEM).To achieve different behaviors of CTD,some modifications are designed on a pseudo-2D internally circulating fluidized bed,which traditionally composes of a high-velocity upward bed and low-velocity downward bed.These modifi-cations include making the air distributor slope and/or laying a baffle in the downward bed.First,the CTD and evolution of particle size distribution under different bed structures are compared.The CTD directly influences the coating uniformity.By making the particles flowing along a parallel direction in the downward bed through the geometrical modifications,the CTD becomes narrower and the coating uniformity is significantly improved.Second,under the optimized bed structure,the influence of oper-ating conditions on the coating uniformity is studied.Properly increasing the fluidization gas velocity and the fluidization gas temperature and reducing the liquid spray rate can improve the coating uniformity.

Effects of hypoxia on promoter of telomerase reverse transcriptase and cell cycle distribution in neonatal rat cardiac myocytes

On the hypothesis that telomerase reverse transcriptase (TERT) of cardiac myocytes (CMs) is consistent with cell cycle distribution as well as tumour cells, we plan to investigate the expression of TERT in CMs and how TERT is in keeping with CMs cycle distribution after birth and under hypoxia, and roughly understand how hypoxia affects activity of TERT promoter.

DISTRIBUTIONS OF LIMIT CYCLES FOR POLYNOMIAL VECTOR FIELDS (P_2, Q_3)

The distributions of limit cycles of cubic vector fields (P2, Q3) are considered in this paper, where P2 and Q3 are polynomials of x and y of order two and three, respectively. It is possibly seven different distributions of limit cycles given in [1]. We now prove that in which three kinds of distributions are impossible and other four kinds all can be realized by concrete vector fields of (P2,Q3). Some related results are also given.

Bifurcations of Limit Cycles in a Z_4-Equivariant Quintic Planar Vector Field

In this paper, a Z4-equivariant quintic planar vector field is studied. The Hopf bifurcation method and polycycle bifurcation method are combined to study the limit cycles bifurcated from the compounded cycle with 4 hyperbolic saddle points. It is found that this special quintic planar polynomial system has at least four large limit cycles which surround all singular points. By applying the double homoclinic loops bifurcation method and Hopf bifurcation method, we conclude that 28 limit cycles with two different configurations exist in this special planar polynomial system. The results acquired in this paper are useful for studying the weakened 16th Hilbert＇s Problem.

偶图K_(n,n+7)-A(|A|≤3)的圈长分布唯一性(英文)

The cycle length distribution of a graph of order n is denoted by (c1,c2,...,cn), where ci is the number of cycles of length i. In this paper, we obtain that a graph G is uniquely determined by its cycle distribution if: (1) G = Kn,n+7 (n ≥ 10); or (2) G = Kn,n+7 - A (|A| = 1,n ≥ 12); or (3) G = Kn,n+7 - A (|A| = 2,n ≥ 14); or (4) G = Kn,n+7 - (|A| = 3,n ≥ 16), where A - E(Kn,n+7).