Regulation of Copper Transporter 2 Expression by Copper and Cisplatin in Human Ovarian Carcinoma Cells

Abstract

Down-regulation of copper transporter 1 (CTR1) reduces uptake and sensitivity, whereas down-regulation of CTR2 enhances both. Cisplatin (DDP) triggers the rapid degradation of CTR1 and thus limits its own accumulation. We sought to determine the effect of DDP and copper on the expression of CTR2. Changes in CTR1 and CTR2 mRNA and protein levels in human ovarian carcinoma 2008 cells and ATOX1(ϩ/ϩ) and ATOX1(Ϫ/Ϫ) mouse embryo fibroblasts in response to exposure to DDP and copper were measured by quantitative reverse transcriptase-polymerase chain reaction, Western blot analysis, and deconvolution microscopy. DDP triggered rapid degradation of CTR1 in 2008 human ovarian cancer cells. However, it increased the expression of CTR2 mRNA and protein levels. Expression of CTR2 was heavily modulated by changes in intracellular copper concentration; copper depletion produced rapid disappearance of CTR2, whereas excess copper increased the level of CTR2 protein. This increase was associated with an increase in CTR2 mRNA and prolongation of the CTR2 half-life. Consistent with prior observations that short hairpin RNA interference-mediated knockdown of CTR2 enhanced DDP uptake and tumor cell kill, reduction of CTR2 by copper starvation also enhanced DDP uptake and cytotoxicity.Comparison of the ability of copper and DDP to modulate the expression of CTR1 in ATOX1(ϩ/ϩ) and ATOX1(Ϫ/Ϫ) indicated that ATOX1 participates in the regulation of CTR2 expression. Unlike CTR1, the expression of CTR2 is increased rather than decreased by DDP. Therefore, these two copper transporters have opposite effects on DDP sensitivity. CTR2 expression is regulated by copper availability via the copper-dependent regulator ATOX1.

Hyperthermic potentiation of cisplatin by magnetic nanoparticle heaters is correlated with an increase in cell membrane fluidity

“…[9][10][11][12][13][14][19][20][21][22][23][24] It is widely accepted as the primary mechanism of influx of this platinum-based drug in cells. 10,11 To assess the effect of extracellular copper on this form of drug transport, the surviving fraction and viability ratio of Caco-2 cells was studied by exposing cells to a mixture of 5 µM copper and increasing concentrations of cDDP for 2.5 hours.…”

“…[14][15][16][17] Although some groups report distinct molecular behaviors of the different members of the hCTR family, which appear to be cell-dependent, all reports agree that copper, due to its affinity with the hCTR receptor, affects receptormediated entry of cDDP negatively, resulting in improved cytotoxicity. 9,[18][19][20][21][22][23] Although copper receptors have a critical role in the uptake of cisplatin, one of the first studies that focused on the mechanisms of thermal enhancement of cDDP reported an increase in cell membrane fluidity, which in turn augmented the uptake of cDDP. 17,24,25 Therefore, the synergism of cDDP and hyperthermic treatment can potentially be explained in the context of membrane fluidity.…”

Research Tools and Techniques for Copper Metabolism in Mammals

“…9,10) The expression of Ctr1 was increased under the Cu-depleted state, whereas that of Ctr2 was markedly suppressed by the Cu depletion. 11,12) Thus, the putative function of Ctr2 may be different from that of Ctr1. Cu-transporting P-type ATPases, i.e., Atp7a and Atp7b, are expressed on the Golgi apparatus and participate in the efflux of Cu from cells.…”

Inhibition of drug resistance in two cancer cell lines(MDR and A2780CIS) in vitro; and the role of selected single nucleotide polymorphisms in cancer

“…can be modified after treatment by special compounds, and this is also true for the other two transporters, the P-type transporters ATP7A and ATP7B (78). The mechanism of cisplatin resistance in the A2780cis cells is still not fully determined, therefore, further investigation is required; however, the resistance is supposedly due to a multifactorial mechanism including altered transporter expression patterns, mismatch repair and cell-cycle modification (31).…”

“…in intracellular membranes but also in the nucleus and that exposure to either copper or cisplatin increased the level of CTR2 in the nucleus as well as in the cytoplasm (78 ATP7A is expressed in the intestinal epithelium as well as most other tissues other than liver, and the pathology of X-linked Menkes disease reflects inadequate mobilization of copper from a number of tissues such as intestine, kidney and blood-brain barrier (82)(83)(84)(85).…”