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Aim To study the effect of G protein-coupled estrogen receptor(GPER)inhibitor G15 on the sensitivity of breast cancer tamoxifen-resistant cells to T-47DTR. Methods Experiments were carried out with 4-hydroxytamoxifen(4-OHT),the active form of tamoxifen in vivo. The sensitivity of tamoxifen-resistant breast cancer cell line T-47DTR and its parental cell line T-47D to tamoxifen was detected by MTT assay; the expression of GPER protein was analyzed by plasma separation of inhibitor G15; the effect of 4-OHT combined with G15 on the apoptosis of T-47DTR cells was analyzed by flow cytometry AnnexinV-FITC/PI double staining; the expression levels of apoptosis-related proteins Bax,Bcl-2,caspase-3,cleaved caspase-3,caspase-9,cleaved caspase-9 were analysed by Western blot. Results(1)Compared with the parental cell T-47D,the resistance of T-47DTR-resistant cells to 4-OHT was significantly enhanced.(2)When 4-OHT(2 μmol·L-1)was administered,the membrane distribution of GPER increased,indicating that GPER was activated in T-47DTR-resistant cells compared with the control group; Compared with OHT,the use of G15(5 μmol·L-1)and OHT significantly reduced the expression of GPER.(3)GPER inhibitor G15 could increase the apoptotic rate of T-47DTR-resistant cells while down-regulating the anti-apoptotic protein Bcl-2 and up-regulating the expression of pro-apoptotic proteins Bax,cleaved caspase-3,cleaved caspase-9. Conclusions The GPER inhibitor G15 increases the apoptosis of T-47DTR cells and restores the sensitivity of drug-resistant cells to tamoxifen.
RESUMO
<p><b>AIM</b>To develop an HPLC method for the determination of crocetin in rat plasma and study the pharmacokinetics in rats.</p><p><b>METHODS</b>Hypersil C18 column (5 microns, 4.6 mm x 200 mm) was used at column temperature 30 degrees C. The mobile phase consisted of methanol-water-acetic acid (75:24.5:0.5) at the flow rate of 1.0 mL.min-1. The UV detection wave length was 423 nm.</p><p><b>RESULTS</b>The calibration curve was linear (gamma = 0.9996) in the range from 0.49 microgram.mL-1 to 7.87 micrograms.mL-1 for crocetin. The mean recovery was 105.2%. The lowest detectable concentration of crocetin was 0.14 microgram.mL-1 (S/N = 3). The RSDs of within-day and between-day were all less than 5%. The plasma crocetin was steady. The HPLC method of determination of crocetin in the plasma was established. After single dose of 50 mg.kg-1 ig in 10 rats, the main pharmacokinetic parameters were estimated as follows: T1/2 alpha (30 +/- 6) min, Tmax(65 +/- 16) min, Cmax(5.0 +/- 1.0) microgram.mL-1, AUC0-T(845 +/- 109) microgram.min.mL-1, Vd(5.0 +/- 0.8) L.kg-1. Crocetin was shown to be absorbed into the blood through the gastrointestinal tract.</p><p><b>CONCLUSION</b>This method is quick, precise and reliable. Crocetin was shown to be quickly absorbed in rats.</p>