In NH4Cl-NH2CH2NH2-EDTA (pH = 9.0) supporting electrolyte containing cupferron, chromium( Ⅵ) complex with cupferron has a rather sensitive adsorptive wave. The reduction peak potential is -1.45V. The determination limit is 9,6?10-10mol/L. This method has been successfully used to samples of tea, grain and water.

The aim of the present study was to develop three-dimensional (3D) culture model, a more pathologically relevant model, of human breast cancer for drug resistance study. MCF-7 cells were embedded within collagen gel to establish 3D culture model. Cellular morphology was observed using Carmine and HE staining. Cell proliferation was evaluated by CCK-8 assay, and cell activity was detected by Live/Dead staining kit. Drug sensitivities of the 3D culture to doxorubicin, carboplatin, 5-fluorouracil were assayed and compared with those of monolayer (2D) culture. In addition, the levels of drug resistance-related genes P-glycoprotein (P-gp), mrp2 mRNA expressions were detected by real time RT-PCR. Expression level of P-gp protein was detected by Western blot. The results showed that MCF-7 cells in 3D culture formed a number of cell aggregates, and most of them displayed good cell viability. The IC50 values of doxorubicin, carboplatin, 5-fluorouracil were all increased significantly in 3D culture compared with those in 2D culture. Moreover, compared with MCF-7 cells in 2D culture, the cells in 3D culture showed increased mRNA levels of P-gp and mrp2, as well as up-regulated protein expression of P-gp. These results suggest that in vitro collagen-embedded culture system of human breast cancer cells represents an improved pathologically relevant 3D microenvironment for breast cancer cells, providing a robust tool to explore the mechanism of drug resistance of cancer cells.
ATP-Binding Cassette, Sub-Family B, Member 1 ; Breast Neoplasms ; Cell Culture Techniques ; Cell Proliferation ; Cell Survival ; Doxorubicin ; Drug Resistance, Neoplasm ; Humans ; MCF-7 Cells