Design, synthesis, and biological evaluation of novel polymyxin B analogues / 药学学报

Polymyxin B and polymyxin E (colistin) are increasingly used as last-resort drugs for treatment of infections caused by multidrug-resistant gram-negative pathogens. Unfortunately, the application was limited due to the serious side effects, especially nephrotoxicity. Very recently, the need for developing more tolerated and more effective polymyxin analogues has grown. This study details the design, synthesis, and evaluation of two classes of polymyxin B analogues with varying hydrophobicity and bulkiness at the N-terminal fatty acyl chain or position 6 amino acid. 20 polymyxin B analogues were synthesized and the chemical structures of the analogues were confirmed by HR-MS and 1H NMR spectra. Compounds 7e (MIC: 0.5-4 μg·mL-1) and 7l (MIC: 0.25-2 μg·mL-1) showed similar or better antimicrobial activity against both susceptible and resistant strains of Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa compared to polymyxin B (MIC: 0.5-2 μg·mL-1). Besides, compound 7l (CC50: 217.1±13.2 μg·mL-1) displayed noticeably decreased renal cytotoxicity compared to polymyxin B (CC50: 120.3±6.0 μg·mL-1). This work establishes the base of further study on the structure-activity relationship of polymyxin B.

Tumor heterogeneity and drug resistance of targeted antitumor agents / 药学学报

The popular application of targeted antitumor agents has greatly improved the efficacies of tumor therapy. However, some patients develop drug resistance after the administration with them for six to twelve months, leading to the failure of treatment. The cause of it is mainly due to tumor heterogeneity. The genesis of tumor heterogeneity is closely associated with tumor stem cells, genetic instability, cell competition and stochastic events. There are a lot of mechanisms involved in the drug resistance to the targeted agents. Tumor heterogeneity and drug resistance are great challenges for precision oncology and are taken account for the process of research and development of new antitumor agents.

Mechanisms of yanshu injection for overcoming multidrug resistance in breast carcinoma MCF-7 cells: an experimental research / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To investigate the mechanism of Yanshu Injection (YI) for overcoming multidrug resistance in breast carcinoma MCF-7 cells.</p><p><b>METHODS</b>Human breast carcinoma MCF-7 cells and doxorubicin-resistant MCF-7/DOX cells were treated with YI. Its inhibition on the cell proliferation was detected by MTT assay. The fluorescence intensity of doxorubicin was detected by flow cytometry. The expression of apoptosis related protein and P-glycoprotein were examined by immunoblotting after treated by YI.</p><p><b>RESULTS</b>The inhibitory action of YI on MCF-7/DOX cells was similar to that of MCF-7 cells, indicating no cross resistance (P > 0.05). 1/16 YI could obviously induce the apoptosis of MCF-7 cells and DOX cells. 1/256 YI +5 nmol/L doxorubicin and 1/128 YI +5 nmol/L doxorubicin could reduce the survival rate of MCF-7/ DOX resistant cells from 86.8% to 74.6% (P < 0.05) and 71.6% (P < 0.01) respectively, showing obvious synergistic effect. Besides, the accumulation of doxorubicin was increased after treated by YI in the MCF-7/ DOX cells. Results of immunoblotting indicated that reduction of P-glycoprotein expression was detected in MCF-7/DOX cells after exposure to YI.</p><p><b>CONCLUSION</b>YI could overcome the multidrug resistance in breast carcinoma MCF-7 cells possibly through reducing the expression of P-glycoprotein.</p>

Study of a novel compound 2460A with activities produced by fungus / 药学学报

With IL-6R as target, a new compound 2460A was identified from fungus using HTS screening model. The taxonomics of the produced strain was confirmed to be Trichoderma hazianum rifai after sequencing analysis of rDNA-ITS (internal transcribed spacer). Results showed that this compound has a binding activity on IL-6R competed with IL-6, thus it is a new ligand of IL-6R originating from microbe. With MTT assay, the anti-tumor activities of 2460A were demonstrated on CM126 and HT-29 cell lines separately, the IC50 are 2.17 x 10(-5) mol x L(-1) and 1.8 x 10(-5) mol x L(-1) respectively. The compound affected lightly the HT-29 cell cycle at S phase. Studies for the anti-tumor activity of 2460A in vivo are in progress in our lab.

Mechanism of Chinese herbal compound Zilongjin for antagonizing multi-drug resistance of tumor cells / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To explore the mechanism of action of Zilongjin (ZLJ) in antagonizing multi-drug resistance (MDR) of tumor cells.</p><p><b>METHODS</b>MDR tumor cells, including human breast cancer cell line MCF-7 and MCF-7/DOX, and human oral epithelial cancer cells KB and KBV200, were treated with ZLJ. The inhibition of ZLJ on cell proliferation was determined with MTT assay; cell cycle and fluorescence dye Rhodamine 123 intensity were detected by flow cytometry; and the expression of related proteins was examined by Western blot.</p><p><b>RESULTS</b>IC50 values in MDR cells after ZLJ treatment were similar to those in sensitive cells; MDR cells showed no cross resistance to ZLJ. Flow cytometric analysis showed that the cell cycles of either sensitive or MDR cells were arrested at S phase after exposure to ZLJ. Using ZLJ singly showed a weak inhibition on MDR of MCF-7/ DOX and KBV200 cells, but when used in combining with doxorubicin or vincistine, it evidently increased their cytotoxicity. Expression of P-glycoprotein in MCF-7/DOX cells decreased after ZLJ treatment in a time-dependent manner. Western blot showed that ZLJ could cause the apoptosis marker protein PARP cleavage to initiate the apoptotic pathway.</p><p><b>CONCLUSIONS</b>The proliferation of tumor cells with MDR could be inhibited by ZLJ and they show no cross resistance to ZLJ. The inhibitory effect is related to the activation of apoptotic pathway and the decrease of P-glycoprotein expression.</p>

Characteristics of boningmycin induced cellular senescence of human tumor cells / 药学学报

Cellular senescence is one of the important steps against tumor. This study was to observe the characteristics of boningmycin induced senescence of human tumor cells. MIT method and clone formation assay were used to detect the growth-inhibitory effect. Cellular senescence was detected with senescence-associated beta-galactosidase staining. Cell cycle distribution and accumulation of intracellular reactive oxygen species (ROS) were analyzed with flow cytometry. Protein expression was detected by Western blotting. The results showed that the growth-inhibitory effect of boningmycin was obviously stronger on human oral epithelial carcinoma KB cells than that on non-small cell lung cancer A549 cells. Comparison to the similar action of doxorubicin, that boningmycin induced the features of cellular senescence in both cell lines, its due to the arrest at G2/M phase and an increase of ROS level. The molecular senescence marker P21 increased significantly after boningmycin treatment at a dosage of 0.1 micromol x L(-1), whereas a higher concentration of it induced apoptosis. The results indicated that cellular senescence induced by boningmycin was one of its mechanisms in tumor suppression.

Role of prosurvival molecules in the action of lidamycin toward human tumor cells / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>Lidamycin, an enediyne antibiotic, leads to apoptosis and mitotic cell death of human tumor cells at high and low concentrations. The reason why tumor cells have distinct responses to lidamycin remains elusive. This study was to elucidate if cellular prosurvival molecules are involved in these responses.</p><p><b>METHODS</b>Cleavage of chromatin and DNA was observed by chromatin condensation and agarose gel electrophoresis. Accumulation of rhodamine 123 in lidamycin-treated cells was assayed by flow cytometry. Cell multinucleation was detected by staining with Hoechst 33342. Western blot and senescence-associated beta-galactosidase (SA-beta-gal) staining were used to analyze protein expression and senescence-like phenotype, respectively.</p><p><b>RESULTS</b>SIRT1 deacetylase remained unchanged in 0.5 nmol/L lidamycin whereas cleavage occurred when apoptosis was induced by lidamycin. Increased FOXO3a, SOD-1 and SOD-2 expression and transient phosphorylation of ERK were detected after exposure of human hepatoma BEL-7402 cells to 0.5 nmol/L lidamycin. High expressions of SIRT1 and Akt were found in colon carcinoma HCT116 p53 knock-out cells exposed to lidamycin. Degradation of PARP and p53 by lidamycin as a substitute for SIRT1 and Akt was confirmed with caspase inhibitor Q-VD-OPh and proteasome inhibitor MG132. Resistance to lidamycin-induced DNA cleavage was observed in breast cancer doxorubicin-resistant MCF-7 cells. This was not induced by P-glycoprotein as no accumulation of rhodamine 123 was detected in the resistant cells following exposure to lidamycin. In contrast to sensitive MCF-7 cells, a lower multinucleation rate for the resistant cells was measured following exposure to equal concentrations of lidamycin.</p><p><b>CONCLUSIONS</b>Cellular prosurvival molecules, such as SIRT1, Akt, SOD-1, SOD-2 and other unknown factors can influence the action of lidamycin on human tumor cells.</p>

Reversal of apoptotic resistance by Lycium barbarum glycopeptide 3 in aged T cells / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To study whether Lycium barbarum glycopeptide 3 (LBGP3) affects T cell apoptosis in aged mice.</p><p><b>METHODS</b>LBGP3 was purified with DEAE cellulose and Sephadex columns. Apoptotic "sub-G1 peak" was detected by flow cytometry and DNA ladder was resolved by agarose gel electrophoresis. Levels of IFN-gamma and IL-10 were measured with specific kits and mRNA expression was detected by RT-PCR. Apoptosis-related proteins of FLIP, FasL, and Bcl-2 were determined by Western blotting.</p><p><b>RESULTS</b>LBGP3 was purified from Fructus Lycii water extracts and identified as a 41 kD glycopeptide. Treatment with 200 microg/mL LBGP3 increased the apoptotic rate of T cells from aged mice and showed a similar DNA ladder pattern to that in young T cells. The reversal of apoptotic resistance was involved in down-regulating the expression of Bcl-2 and FLIP, and up-regulating the expression of FasL.</p><p><b>CONCLUSION</b>Lycium barbarum glycopeptide 3 reverses apoptotic resistance of aged T cells by modulating the expression of apoptosis-related molecules.</p>

Mechanism of apoptosis induced by SIRT1 deacetylase inhibitors in human breast cancer MCF-7 drug-resistant cells / 药学学报

The mechanism of apoptosis induced by SIRT1 deacetylase inhibitors in both human breast cancer MCF-7 and MCF-7 doxorubicin-resistant cells was studied. MTT assay was used to detect growth-inhibitory effect on the cells. Protein expression was detected by Western blotting. Chromatin condensation was detected by a fluorescent microscope after Hoechst 33342 staining. Cell cycle distribution was analyzed with flow cytometry. Apoptotic cells were detected with Annexin V staining. Nicotinamide (NAM) and Sirtinol, two SIRT1 deacetylase inhibitors, exhibited the similar growth-inhibitory effects on MCF-7/DOX cells and MCF-7 cells, but no potentiation of DOX activities. The arrest at G2/M phase was detected by flow cytometry in both MCF-7 and MCF-7/DOX cells after NAM treatment. Activation of caspase pathway in MCF-7 cells, such as the cleavages of PARP, caspase-6, -7, -9, were observed after exposure to NAM 50 mmol x L(-1), accompanied by the occurrence of chromatin condensation and Annexin V positive cells. However, the cleavages of PARP, caspase-6 and -7 in MCF-7/DOX cells delayed after exposure to NAM for 24 h and obviously increased at 48 h with appearance of chromatin condensation and Annexin V positive cells. SIRT1 deacetylase inhibitors show no cross resistance to MCF-7 drug-resistant cells, and the similar growth-inhibitory actions of them to MCF-7 sensitive and drug-resistant cells by which it is mediated by activation of apoptotic caspase pathway.