Objective To investigate the effects and molecular mechanism of tamoxifen on cell cycle distribution of ER-negative MDA-MB-231 cells re-expressing exogenous ER? gene under induction of Vit D3. Methods ER?/pcDNA3.1+ eukaryotic plasmid containing 4 copies of vitamin D response elements (VDRE) and Tk promoter was transfected into MDA-MB-231 cells. MTT assay and flow cytometry were used to analyze the inhibitory effects of Vit D3 and Tamoxifen on cell proliferation and cell cycle distribution. Then RT-PCR and Western blot assay were employed to detect the expressions of Cyclin D1, CDK4, Rb and phosphorylated Rb. The binding affinity of Cyclin D1/CDK4 complex was also analyzed by using immunoprecipitation assay. Results After concomitant treatment with Vit D3 and Tamoxifen for 72 h, Vit D3 and Tamoxifen synergetically inhibited proliferation of MDA-MB-231VDRE-ER? cells, and the majority of cells were arrested in G0/G1 phase. Cyclin D1 expression and the binding affinity of Cyclin D1/CDK4 complex were markedly down-regulated after 24 h of the concomitant treatment. Concurrently, the phosphorylation of Rb protein was also effectively inhibited while its expression exhibited no evident changes. Conclusion Vit D3 could effectively restore the sensitivity of ER-negative breast cancer cells transfected with exogenous ER? vector containing VDREs-Tk promoter to Tamoxifen by regulating the expression and activity of G1/S phase-related molecules.

Objective To study the effect of 1,25-dihydroxyvitamin D_(3) and Tamoxifen on cell cycle distribution and apoptosis of MDAMB-231 cells transfected with ER? expression vector containing vitamin D response element.Methods The 4 VDRE-Tk sequence of VDRE-pGL3 reporter vector was cloned into ER?/pcDNA3.1+ vector and then was transfected into MDA-MB-231 breast cancer cells.MDA-MB-231~(VDRE-ER?) breast cancer cells were treated with 1,25-dihydroxyvitamin D_(3) and Tamoxifen to observe their pro-apoptotic effect by TUNEL and to determine whether cell cycle progression could be repressed by FCM.Results As compared with control group,MDA-MB-231~(VDRE-ER?) cells at G_(0)/G_(1) phase increased profoundly after treated with 1,25-dihydroxyvitamin D_(3) and Tamoxifen for 72 h.Meanwhile,1,25-dihydroxyvitamin D_(3) and Tamoxifen synergistically induced the apoptosis of MDA-MB-231~(VDRE-ER?) cells.Conclusion Transfection of VDRE-Tk-ER? expression vector into ER?-negative breast cancer cells could effectively recover its responsiveness to Tamoxifen under the induction of 1,25-dihydroxyvitamin D_(3) by blocking the cell cycle progression and inducing apoptosis.

Objective:To observe the inhibitory effects of VD3 and Tamoxifen on ER-negative breast cancer cells transfected with human recombinant pVDRE-Tk-ER? eukaryotic expression plasmid in vivo. Method:A recombinant human ER? expression plasmid containing 4 copies of VDRE and Tk promoter was introduced into the ER-negative MDA-MB-231 breast cancer cell. The transformed breast cancer cells were inoculated into athymic nude mice. 4 w after tumor inoculation,mice bearing the tumor of approximately 200 mm3 were treated with 0.5?g/kg of VD3 and/or 50mg/kg of Tamoxifen(SC) for 20d. The tumor volume was precisely measured,concurrently HE stain and Ki-67 immunohistochemical(IHC) assay were performed to detect the anti-proliferative effect of Vit D3 in combination with Tamoxifen in vivo. Results:After 20d of treatment,VD3 and Tamoxifen synergistically decreased the tumor volume as compared with control group. And the IHC results also showed that the Ki-67 expression was significantly inhibited by co-treatment of VD3 and Tamoxifen,which means the arrest of cell cycle progression. Conclusion:VD3 could effectively restore the sensitivity of ER-negative breast cancer cells to Tamoxifenby inducing the expression of exogenous ER? gene through the VDRE and Tk promoter in vivo.

Objective To observe the synergistic effects of Herceptin(HER)and 9-cis-retinoic acid (9-cis-RA) on HER2/neu positive breast cancer cells in vivo. Method MCF-7 breast cancer cells transfected with exogenous HER2 gene were inoculated into athymic nude mice. Four weeks after tumor inoculation,mice bearing a tumor of 200 mm3 in volume approximately were selected to be treated with HER and/or 9-cis-RA(SC) for 20d. After that tumor volume was precisely measured,concurrently the HE staining and Ki-67 immunohistochemical (IHC) assay were performed to detect the anti-proliferative effect of HER in combination with 9-cis-RA in vivo. Results After 3 w of treatment,HER and 9-cis-RA synergistically decreased the tumor volume as compared with control group. IHC results showed that Ki-67 expression was significantly inhibited by co-treatment of HER and 9-cis-RA,which means the arrest of cell cycle progression. Conclusion Herceptin and 9-cis-RA could synergistically inhibit the proliferation of HER2 positive breast cancer cells in vivo.

Objective To investigate the synergistic effects of Herceptin and 9-cis-RA on the proliferation, cell cycle and apoptosis of HER2-positive breast cancer cells. Methods MDA-MB-453 breast cancer cells were treated with 5 ?g/ml Herceptin or 1 ?mol/L 9-cis-RA or both for 24, 48 or 72 h. The proliferation of MDA-MB-453 breast cancer cells was determined by MTT, the pro-apoptotic effects were detected by TUNEL, the cell cycle phase was detected by FCM. Results As compared with control group, Herceptin and 9-cis-RA synergistically inhibited the proliferation of MDA-MB-453 breast cancer cells, and the percentage of G_ 0 /G_ 1 cells increased after treatment with Herceptin and 9-cis-RA for 72 h. Simultaneously, Herceptin and 9-cis-RA synergistically induced the apoptosis of MDA-MB-453 cells. Conclusion Herceptin and 9-cis-RA could synergistically and effectively inhibit MDA-MB-453 breast cancer cells by blocking their cell cycle progression and inducing their apoptosis.

Objective:To investigate the mechanisms of genistein (GEN) affecting the chemosen- sitivity of human breast cancer cell line MDA-MB-453 to paclitaxel (PTX) in vitro. Method:HER2/neu- overexpressing breast cancer cells MDA-MB-453 were treated by GEN, PTX alone or combined in vitro. Cell cycle was measured by flow cytometry. The expression of HER2/neu protein was observed by immunocytochemistry and. Akt, p-Akt, cyclin B1 and CDK1 protein by Western blot. Results:Cell cycle of MDA-MB-453 cells was blocked at G1/S after treatment of GEN, while at G2/M after treatment with PTX alone. Both GEN and PTX did not change the expression of HER2/neu, total Akt and CDK1 in MDA-MB-453 cells, but GEN significantly decreased p-Akt and cyclin B1 level, and PTX obviously increased cyclinB1 level. GEN antagonized the effects of PTX on level of cyclin B1 protein and blockage of G2/M in MDA-MB-453 cells after treatment with GEN and PTX in combination. Conclusion:The antagonism effects of GEN on the increase of cyclin B1 and blockage of G2/M induced by PTX may be one of the mechanisms of GEN affecting the chemosensitivity of MDA-MB-453 cells to PYX.

Objective To investigate the effects of lovastatin on MAPK activity in MCF 7 breast cancer cells. Methods After MCF 7 cells were treated with 4, 8 and 16 ?mol/L lovastatin for 48～72 h, the expressions of ERK1 and p38 MAPK proteins were detected by Western blotting. Their phosphorylation levels were observed by kinase activity assay. Results MCF 7 cells treated with different doses of lovastatin for 48～72 h had no significant effect on the protein level of ERK1, but the activities of ERK1 and the P38 MAPK proteins were down regulated at 72 h after treatment. Conclusion Lovastatin may down regulate the activity of MAPK in MCF 7 cells by means of inhibiting the mevalonate metabolism pathway and/or affecting phosphorylation levels.

Objective To summarize our experience on the food safety for residents and disaster relief workers in Li county after Wenchuan earthquake in Sichuan province.Methods A comprehensive survey was conducted to assess the current food hygiene status.According to the survey results,we had integrated the local forces and strengthened the food hygiene surveillance and quality detection focusing on the crucial procedures.Besides,effective health educations were applied to advocate the rational dietary after earthquake.Results There was no any food safety incident in the county,and the hygiene awareness of local residents has been improved.Conclusion Powerful organization,focused management and multi-collaboration are the important elements to accomplish the food safety control after earthquake.

Polymyxin B and polymyxin E (colistin) are presently considered the last line of defense against human infections caused by multidrug-resistant Gram-negative organisms such as carbapenemase-producer Enterobacterales, Acinetobacter baumannii, and Klebsiella pneumoniae. Yet resistance to this last-line drugs is a major public health threat and is rapidly increasing. Polymyxin S₂ (S₂) is a polymyxin B analogue previously synthesized in our institute with obviously high antibacterial activity and lower toxicity than polymyxin B and colistin. To predict the possible resistant mechanism of S₂ for wide clinical application, we experimentally induced bacterial resistant mutants and studied the preliminary resistance mechanisms. Mut-S, a resistant mutant of K. pneumoniae ATCC BAA-2146 (Kpn2146) induced by S₂, was analyzed by whole genome sequencing, transcriptomics, mass spectrometry and complementation experiment. Surprisingly, large-scale genomic inversion (LSGI) of approximately 1.1 Mbp in the chromosome caused by IS26 mediated intramolecular transposition was found in Mut-S, which led to mgrB truncation, lipid A modification and hence S₂ resistance. The resistance can be complemented by plasmid carrying intact mgrB. The same mechanism was also found in polymyxin B and colistin induced drug-resistant mutants of Kpn2146 (Mut-B and Mut-E, respectively). This is the first report of polymyxin resistance caused by IS26 intramolecular transposition mediated mgrB truncation in chromosome in K. pneumoniae. The findings broaden our scope of knowledge for polymyxin resistance and enriched our understanding of how bacteria can manage to survive in the presence of antibiotics.