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

Metallomics. 2018 Mar 1;10(3):414-425. doi: 10.1039/c7mt00334j. Epub 2018 Feb 8.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Apoptosis
  • Biological Transport
  • Cation Transport Proteins / genetics
  • Cation Transport Proteins / metabolism*
  • Colorectal Neoplasms / drug therapy
  • Colorectal Neoplasms / metabolism*
  • Colorectal Neoplasms / pathology
  • Copper Transporter 1
  • Drug Resistance, Neoplasm*
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Octamer Transcription Factor-1 / genetics
  • Octamer Transcription Factor-1 / metabolism*
  • Octamer Transcription Factor-3 / genetics
  • Octamer Transcription Factor-3 / metabolism*
  • Organic Cation Transporter 2 / genetics
  • Organic Cation Transporter 2 / metabolism*
  • Oxaliplatin / pharmacology*
  • Tumor Cells, Cultured

Substances

  • Antineoplastic Agents
  • Cation Transport Proteins
  • Copper Transporter 1
  • Octamer Transcription Factor-1
  • Octamer Transcription Factor-3
  • Organic Cation Transporter 2
  • POU2F1 protein, human
  • POU5F1 protein, human
  • SLC22A2 protein, human
  • SLC31A1 protein, human
  • Oxaliplatin