Translocation of Platinum Anticancer Drugs by Human Copper ATPases ATP7A and ATP7B

Abstract

Cisplatin, carboplatin, and oxaliplatin are widely used anticancer drugs. Their efficacy is strongly reduced by development of cell resistance, a phenomenon not entirely understood, with contribution of drug detoxification, defective accumulation, and efflux from the cell. Downregulation of CTR1, responsible for Cu uptake by the cell, and up-regulation of the Cu-ATPases, ATP7A and ATP7B, which accept Cu from the cytosolic chaperone Atox1 and transfer the metal ion into the secretory pathway where it is incorporated into cuproenzymes, have been associated to augmented drug resistance. To gain information on translocation of Pt drugs by human CuATPases, we performed electrical measurements on COS-1 cell microsomal fraction, enriched with recombinant ATP7A, ATP7B, and selected mutants, adsorbed on a solid supported

Clinical outcome of cisplatin-based chemotherapy is associated with the polymorphisms of GSTP1 and XRCC1 in advanced non-small cell lung cancer patients

“…ATP7A mediates the transport of platinum drugs across the cellular membranes, and is considered to sequester platinum agents in intracellular compartments and to prevent their reaction with nuclear DNA [24,25]. A correlation between the expression of ATP7A and the degree of acquired resistance to platinum drug in cultured cells and tumor samples suggests that the copper transporters are important constituents of the program that regulates sensitivity to platinum drugs [26,27]. ATP7A C2299G, mutated in high frequency of 23.2 % in Chinese population, can change the gene functions.…”

Differential Reactivity of Metal Binding Domains of Copper ATPases towards Cisplatin and Colocalization of Copper and Platinum

“…All MBDs of these ATPases share a high sequence homology and exhibit similar protein folding with a conserved Cu I ‐binding motif CXXC . In addition, all of the MBDs show similar binding affinity to cuprous ion .…”

“…It has been reported that pre‐loading with Cu can enhance the platination of copper chaperones Atox1 and Cox17, in spite of the fact that Pt II and Cu I bind to the same coordination site . In order to investigate the effect of Cu I on the platination of these ATPases, the reaction with cisplatin was conducted on Cu‐loaded proteins.…”

“…The reaction of apo‐MNK6 with cisplatin generates two chromatographic peaks falling at 11 and 13 mL retention volumes; in contrast only one peak at 9 mL retention volume is generated in the case of Cu‐MNK6 (Figure C and D). The two peaks observed in the case of apo‐MNK6 could be due to formation of a monofunctional and a bifunctional platinum adduct, as observed in a previous work on MNK1 . Thus, these results also fully confirm the fluorescence data, indicating that the reaction rate is dependent upon the nature of the MBD and of its loading with Cu.…”

“…As mentioned in the introduction, the expression level of Cu‐ATPases positively correlates with cisplatin resistance of cancer cells . It was also demonstrated that ATP7A/B can translocate cisplatin or oxaliplatin in an ATP‐dependent way . The translocation in the case of Pt II occurs with a rate comparable to that of Cu I and with equal amount of positive charge displaced upon ATP utilization within a single catalytic cycle.…”