Rapamycin induces differentiation of glioma stem/progenitor cells by activating autophagy / 癌症

Glioma stem/progenitor cells (GSPCs) are considered to be responsible for the initiation, propagation, and recurrence of gliomas. The factors determining their differentiation remain poorly defined. Accumulating evidences indicate that alterations in autophagy may influence cell fate during mammalian development and differentiation. Here, we investigated the role of autophagy in GSPC differentiation. SU-2 cells were treated with rapamycin, 3-methyladenine (3-MA) plus rapamycin, E64d plus rapamycin, or untreated as control. SU-2 cell xenografts in nude mice were treated with rapamycin or 3-MA plus rapamycin, or untreated as control. Western blotting and immunocytochemistry showed up-regulation of microtubule-associated protein light chain-3 (LC3)-II in rapamycin-treated cells. The neurosphere formation rate and the number of cells in each neurosphere were significantly lower in the rapamycin treatment group than in other groups. Real-time PCR and immunocytochemistry showed down-regulation of stem/progenitor cell markers and up-regulation of differentiation markers in rapamycin-treated cells. Transmission electron microscopy revealed autophagy activation in rapamycin-treated tumor cells in mice. Immunohistochemistry revealed decreased Nestin-positive cells and increased GFAP-positive cells in rapamycin-treated tumor sections. These results indicate that rapamycin induces differentiation of GSPCs by activating autophagy.

Ursolic acid induces human hepatoma cell line SMMC-7721 apoptosis via p53-dependent pathway / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Ursolic acid (UA) is a ubiquitous molecule in the plant kingdom with specific anticancer effects that have been shown in vitro and in vivo. Although UA can inhibit the proliferation of liver cancer cells and induce apoptosis of many types of tumor cells, the molecular mechanism of its anti-hepatoma activity is still not well defined. The objective of this study was to investigate the inhibitory effect and mechanisms of UA on the human hepatoma cell line SMMC-7721.</p><p><b>METHODS</b>After treatment with UA, the growth inhibition of SMMC-7721 cells was assessed by MTT assay. Cells were also evaluated by flow cytometric analysis, Wright-Giemasa staining, Hoechst 33258 staining and transmission electron microscope after they were induced by UA. DNA microarray technology was used to investigate the gene expression pattern of SMMC-7721 cells exposed to UA 40 micromol/L. The molecular mechanism of cells death was analyzed by real-time RT-PCR and Western blotting.</p><p><b>RESULTS</b>The proliferation of SMMC-7721 cells was significantly inhibited in a dose- and time-dependent manner after UA treatment. UA induced cell cycle arrest and apoptosis. The DNA microarray analysis indicated that 64 genes were found to be markedly up- or down-expressed, including GDF15, SOD2, ATF3, and fos. The result of Western blotting showed the apoptotic proteins p53 and Bax were up-regulated while the anti-apoptotic protein Bcl-2 was down-regulated. Real-time RT-PCR confirmed UA could up-regulate the mRNA expressions of GDF15, SOD2, ATF3 and down-regulate the mRAN expression of fos. Meanwhile these effects were partly blocked by pretreatment with the p53 inhibitor Pft-alpha.</p><p><b>CONCLUSION</b>Activation of the p53 pathway is involved in UA inhibition of SMMC-7721 human hepatocellular carcinoma cell growth and induction of apoptosis.</p>

Autophagy is involved in 6-OHDA-induced dopaminergic cell death / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the role of autophagy in the death of dopaminergic neurons induced by 6-hydroxydopamine (6-OHDA).</p><p><b>METHODS</b>Rat models of Parkinson disease (PD) were established by stereotaxic administration of 6-OHDA (8 μg) into the unilateral substantia nigra par compact (SNpc). Autophagosomes in the SNpc were observed with transmission electron microscopy (TEM), and the expression of autophagy-related protein LC3 was determined with immunofluorescence (IF) assay.</p><p><b>RESULTS</b>Under TEM, the autophagosomes were found in the ipsilateral SNpc 6-24 h after 6-OHDA injection, which suggested the activation of autophagy. IF assay showed significantly increased LC3 expression in 6-OHDA-damaged TH-positive neurons as compared to the control group.</p><p><b>CONCLUSIONS</b>The increase of autophagosomes and activation of autophagy may play a role in dopaminergic neuron death induced by 6-OHDA.</p>

Mitochondrial dysfunction and Huntington disease / 神经科学通报·英文版

Huntington disease (HD) is a chronic autosomal-dominant neurodegenerative disease. The gene coding Huntingtin has been identified, but the pathogenic mechanisms of the disease are still not fully understood. This paper reviews the involvement of mitochondrial dysfunction in pathogenesis of HD.

Establishment of an imatinib resistant cell line K562/G01 and its characterization / 中华血液学杂志

<p><b>OBJECTIVE</b>To establish a BCR/ABL+ cell line with resistance to imatinib, and investigate the possible mechanisms of the acquired resistance.</p><p><b>METHODS</b>K562 cells were cultured in gradually increased concentrations of imatinib over a period of several months to generate their resistance line. MTT assay, RT-PCR, Western blotting, and FISH were used to study the possible molecular mechanisms of the resistance.</p><p><b>RESULTS</b>A resistant cell line, K562/G01, was established with 15.2 +/- 3.0-fold resistant to imatinib as compared with that of the parental sensitive cell line. The resistant cell line also had the cross-resistance to a broad spectrum of other anticancer agents excepting for DOX. There was no difference between the two cell lines in terms of the cell morphology, proliferation doubling time, and fraction distribution of cell cycle. K562/G01 cells showed increased levels of BCR/ABL, mdr1 mRNA and their coding proteins and the increased tyrosine kinase activity. No point mutation in the BCR/ABL ATP-binding site was detected while the copies of BCR/ABL fusion gene were increased in K562/G01 cells.</p><p><b>CONCLUSION</b>An imatinib-resistant human leukemia cell line, K562/G01, was established. The mechanisms of resistance of K562/G01 cells to imatinib involved increased expression of BCR/ABL and mdr1/P-gp, amplification of BCR/ABL fusion gene, and increased activity of BCR/ABL.</p>

Effects of quercetin on platelet-endothelial cell adhesion and their expression of adhesion molecules / 药学学报

<p><b>AIM</b>To observe the effect of quercetin (Que) on the adhesion of platelets to cultured endothelial cells and adhesion molecule expression by human umbilical vein endothelial cells (HUVEC) and platelets.</p><p><b>METHODS</b>[3H]-Adenine labeled platelets were incubated with HUVEC to investigate the effect of Que on adhesion of platelets to HUVEC. The number of platelets adhering to the HUVEC monolayer was determined by liquid scintillation spectroscopy. TNF-alpha induced HUVEC expression ICAM-1 and thrombin induced platelets expression of P-selectin were measured by flow cytometry.</p><p><b>RESULTS</b>Que (0.3-2.4 mumol.L-1) was shown to inhibit the increase of P-selectin expression of thrombin activated platelets. Pretreatment of HUVEC with tumor necrosis factor (TNF-alpha) significantly increased platelets adhesion to HUVEC and the expression ICAM-1. Que (0.6-2.4 mumol.L-1) inhibited this effect of TNF-alpha in a concentration-dependent manner.</p><p><b>CONCLUSION</b>Que can inhibit the adhesion of platelets to HUVEC and the expression of adhesion molecules (P-selectin and ICAM-1).</p>

Structure-based design, synthesis and evaluation of bioactivity of anti-P-gp peptide mimetic / 药学学报

<p><b>AIM</b>To design and evaluate the small peptide mimetic of anti-P-glycoprotein (P-gp) antibody (PHMA02).</p><p><b>METHODS</b>From the three dementional structure analysis of computer modeling of PHMA02 CDR loops, a small peptide mimetic was designed and determined by flow cytometry.</p><p><b>RESULTS</b>Anti-P-gp peptide mimetic functionally similar to PHMA02 was developed. The peptide mimetic competitively inhibits PHMA02 binding to P-gp and partially block the P-gp function as a drug efflux pump in K562/A02 cells.</p><p><b>CONCLUSION</b>Some special conformational properties of CDR loops of antibody might serve as lead structures for develop new biological peptide mimetics. Antibody-structure-based design would develop new drug in the future.</p>