Relevance of copper transporter 1 and organic cation transporters 1–3 for oxaliplatin uptake and drug resistance in colorectal cancer cells

Abstract

Oxaliplatin is a routinely used drug in the treatment of colorectal cancer. However, development of resistance is a major hurdle of the chemotherapy success. Defects in cellular accumulation represent a frequently reported feature of cells with acquired resistance to platinum drugs. Nevertheless, the mechanisms of oxaliplatin uptake and their role in oxaliplatin resistance remain poorly elucidated. The aim of this study was to investigate the relevance of copper transporter 1 (CTR1) and organic cation transporters 1-3 (OCT1-3) for oxaliplatin uptake and resistance to the drug in sensitive and oxaliplatin-resistant ileocecal colorectal adenocarcinoma cells. Co-incubation with copper(ii) sulfate, a CTR1 substrate, significantly decreased oxaliplatin accumulation but not cytotoxicity in both cell lines. Pre- as well as co-incubation with the OCT1 inhibitor atropine led to a significant reduction in oxaliplatin accumulation in sensitive but not in resistant cells. However, oxaliplatin cytotoxicity was also decreased in the presence of atropine in both cell lines. Cimetidine, an inhibitor of OCT2, induced a significant reduction in the cellular accumulation and potency of oxaliplatin in sensitive and resistant cells. An inhibitor of OCT3, decynium-22, had no influence on oxaliplatin accumulation and cytotoxicity in either cell line. No differences in the transporter expressions were observed between the cell lines, drug-treated or not, either at the mRNA or protein levels. A fluorescent oxaliplatin derivative CFDA-oxPt co-localized with CTR1, OCT1 and OCT2 in sensitive cells, but only with CTR1 and OCT2 in the resistant cell line. Our results suggest that oxaliplatin is transported into the cell by CTR1 in both cell lines. However, contribution of CTR1-mediated uptake to resistance seems unlikely. Uptake of oxaliplatin via OCT1 appears to take place in the sensitive but not in the resistant cell line underscoring the transporter relevance for oxaliplatin resistance. OCT2 is likely to be involved in the uptake of oxaliplatin to a similar extent in both cell lines suggesting no major contribution of this transporter to resistance. In contrast, OCT3 appears to be irrelevant for oxaliplatin transport into the cell and resistance.

The Temperature-Dependent Effectiveness of Platinum-Based Drugs Mitomycin-C and 5-FU during Hyperthermic Intraperitoneal Chemotherapy (HIPEC) in Colorectal Cancer Cell Lines

“…Another important issue that should be addressed in further research is how the uptake of the drugs is regulated and by which cellular pathway. For the uptake of platinum-based drugs, the copper transporter-1 (CTR-1) and the organic cation transporter 1-3 (OCT1-3) have been described to be important [60,61]. Cui et al demonstrated that different human CRC cell lines express high levels of CTR-1 protein in similar localization patterns, despite the different sensitivity to oxaliplatin [60].…”

The Drug-Resistance Mechanisms of Five Platinum-Based Antitumor Agents

“…Gao et al reported that omeprazole could decrease the protein level of OCT2, thus lead to reduced cellular accumulation of cisplatin . Buss et al (2018) employed a novel fluorescent oxaliplatin FIGURE 2 | A schematic of the mechanisms affecting platinum response. The response toward platinum-based antitumor agents can result from (a) cellular drug accumulation.…”

Redox Stability Controls the Cellular Uptake and Activity of Ruthenium‐Based Inhibitors of the Mitochondrial Calcium Uniporter (MCU)

“…Coincubation with 200 μ m CuSO 4 , which will saturate the copper transporter CTR1, does not alter the cellular accumulation of any of the complexes (Figure D), suggesting that they are not being taken up by this pathway. This result is in contrast to that for the platinum‐based anticancer drugs, whose uptake is correlated to CTR1 expression levels . Incubation with the organic cation transporter (OCT) inhibitor procainamide significantly reduced the cellular uptake levels of Ru265 and Ru265′, but not Ru360′ (Figure E).…”

“…The organic cation transporters OCT1, OCT2, and OCT3 are primarily responsible for the transport of signaling molecules and metabolites such as dopamine, serotonin, and choline. However, these transporters have recently been shown to mediate the uptake of several cationic monofunctional platinum(II) anticancer complexes, suggesting that they may have a more general affinity for coordination complexes.…”