Objective To explore the effect of ?-elemece on the reverse of drug resistance and the expression of P-glycoprotein(P-gp) in MDR K562/ADM cells. Methods MTT method was used to detect the sensitivity of cell and its reverse of drug resistance.Immunohistochemistry and immunoelectron microscopy were for observing the expression of P-gp.It's quantitative analysis was determined by flow cytometry.All experimental data were dealt with by SPSS(10.0 production pacility) soft ware. Results 1.Non-cytotoxic dose of ?-elemece(4.0?mg/L) could obviously decrease the IC-(50) value of K562/ADM cells to ADM.The reversing fold was 2.18;2.The level of P-gp expression was higher in K562/ADM cells than that in its parent K562 cells.Our studies also showed that the distribution of P-gp was on membrane of K562/ADM cells;3.Non-cytotoxic dose of ?-elemece(4.0?mg/L) could remarkably decrease the P-gp expression in MDR K562/ADM cells.Conclusion\ ?-elemece could evidently reverse drug resistance of K562/ADM to ADM.Decreasing the P-gp expression in drug resistance cell is one of the main mechanism of reversion.

Objective To investigate the action mechanism of glutamate-mediated signaling pathway in malignant melanoma. Methods WM451LU melanoma cells in log phase were classified into 6 groups, negative control group treated with PBS (100 μl), MK801 group treated with the non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 (100 μmol/L), CPCCOEt group treated with non-competitive metabotropic glutamate receptor 1 (mGluR1) antagonist CPCCOEt, MAP2 group transfected with adenovirus vector containing microtubule associated protein 2a (Ad-MAP2a), MK801 + MAP2 group treated with MK801 of 100 μmol/L and transfected with Ad-MAP2a, CPCCOEt + MAP2 group treated with CPCCOEt of 10 μmol/L and transfected with Ad-MAP2a. Western blot was performed to detect the expression of an ionotropic glutamate receptor, i.e., N-methyl-D-aspartate receptor type 2A (NMDAR2A) in WM451LU cells transfected with Ad-MAP2a. Scratch motility assay and cell invasion assay were conducted in vitro to detect the changes in migration and invasion ability of WM451LU cells after treated with Ad-MAP2a, MK-801, CPCCOEt alone or in combination. In vivo study was carried out to compare the inhibitory effect of the above treatments on melanoma. Results Western blot revealed a decrease in the expression of NMDAR2A in WM451LU cells after transfected with Ad-MAP2a. The scratch motility assay showed that the number of migrating cells per high power field was 117.04 ± 2.76 in MAP2 group,107.64 ± 6.50 in MK801 group,97.36 ± 4.79 in CPCCOEt group, 43.28 ± 3.02 in MK801 + MAP2 group,30.76 ± 3.97 in CPCCOEt + MAP2 group,significantly different from that in the negative control group (152.3 ± 5.75,all P ＜ 0.01 ). Cell invasion assay demonstrated that the average number of invading cells per high power field in the negative control was significantly higher than that in MAP2 group, MK801 group, CPCCOEt group, MK801+MAP2 group and CPCCOEt + MAP2 group (170.43 ±8.72 vs. 98.26 ± 3.84, 97.22 ± 5.54, 112.23 ± 7.21, 42.89 ± 5.06, 58.25 ± 6.68, P ＜ 0.05, 0.05, 0.05, 0.01and 0.01, respectively).A significant decrease was observed in the average volume of experimental melanoma in mice of MAP2 group, MK801 group, MK801 + MAP2 group, CPCCOEt group and CPCCOEt + MAP2 group compared with the negative control group (224.02 ± 46.19 mm3, 160.33 ± 33.91 mm3, 91.49 ± 21.48 mm3,202.30 ± 52.37 mm3, 111.13 ± 69.81 mm3 vs. 342.70 ± 60.92 mm3, all P ＜ 0.01 ). Conclusions To block the glutamate signaling pathway in vitro can inhibit the invasion and migration of melanoma cells, and to block the pathway in vivo can inhibit the growth of malignant melanoma and alter the morphology of melanoma cells.

Objective To investigate the roles of glutamate signaling pathway in melanin transfer.MethodsEpidermal melanocytes and keratinocytes were isolated from human foreskin tissue followed by purification and primary culture.Immunofluorescence microscopy was conducted to observe the intracellular distribution of N-methy-D-aspartate receptor 1 (NMDAR1) and NMDAR2A in melanocytes.Some melanocytes were classified into 4 groups to be pretreated with MK801 (the NMDAR antagonist dizocilpine maleate) at 100μmol/L for 5 minutes followed by treatment with NMDA(an NMDAR agonist) at 100 μmol/L (MK801-pretreated group 1),pretreated with MK801 at 100 μmol/L for 1 hour followed by treatment with NMDA at 100μmol/L (MK801-pretreated group 2),treated with MK801 at 100 μmol/L for 5 minutes (MK801 group),treated with NMDA at 100 μmol/L for 5 minutes (NMDA group),respectively,then,confocal microscopy was performed to measure the intracellular calcium (Ca2+) concentration of the melanocytes.The distribution of β-tubulin was visualized by confocal microscopy in melanocytes treated with MK801 at 100 μmol/L for 24 hours.Some melanocytes and keratinocytes were cocultured with or without MK801 at 100 μmol/L for 24 or 48 hours,then,scaning microscopy was carried out to observe the junction structure between melanocytes and keratinocytes,and alkali method coupled with spectrophotometric analysis to determine melanin content in keratinocytes.Results The intracellular calcium concentration of melanocytes was decreased by MK-801,but increased by NMDA at 100 μmol/L,and the increase was blocked by the pretreatment with MK-801 for 5 minutes or 1 hour.After incubation with MK-801 at 100 μmol/L for 24 hours,a more intense staining for β-tubulin was observed around the nuclei of melanocytes.There was a significant reduction in the number of filopodia on the surface of and between melanocytes and keratinocytes after treatment with MK-801 at 100 μmol/L for 48 hours.Also,the content of melanin(represented as the absorbance value at 375 nm) transferred from melanocytes into keratinocytes was statistically reduced in coculture system treated with MK-801 at 100 μmol/L compared with that without treatment (0.158 ± 0.003 vs.2.203 ± 0.006,t =6.323,P ＜ 0.01 ).Conclusions The glutamate signaling pathway exerts a regulatory effect on intracellular calcium concentration of distribution of β-tubulin in,filopodia formation of melanocytes and melanin transfer between melanocytes and keratinocytes.