| Cisplatin, a commonly used chemotherapeutic, is limited in its efficacy due to the rapid development of resistance. A common underlying factor in the development of this resistance is a decrease in cellular accumulation of the drug. Recent studies have suggested that the copper transport pathway may be responsible for the uptake and cellular trafficking of cisplatin. The overall goal of the studies described here was to determine whether the Cu plasma membrane transporter hCTR1 plays a role in the cellular accumulation of cisplatin, and if so, whether it influences the sensitivity of cells to this common chemotherapy. This was achieved by using two cellular models, one in which hCTR1 was over expressed and the other in which CTR1 was absent.; Once hCTR1 was identified as an influx transporter of DDP, investigations went on to identify the cellular regulation and trafficking of the protein through the use of chemical inhibitors and dominant negative mutants to block normal endocytotic and proteasomal pathways. The role that hCTR1 may play in the resistance of human tumors to cisplatin was investigated using cisplatin sensitive and resistant ovarian carcinoma cell lines and the screening of human tumor tissue. The experiments described in the following work demonstrate that hCTR1 plays a role in the transport of cisplatin, as alterations of hCTR1 protein levels correspond to platinum accumulation levels. While hCTR1 does appear to influence cisplatin, the results presented here indicate that hCTR1 does not necessarily correlate to drug sensitivity in human cells, as hCTR1 levels were not significantly altered for normal tissue in a majority of human tumors or in sensitive and resistant cell pairs. Finally, the cellular trafficking of hCTR1 depends on the continual cycling of the protein. However, upon exposure to DDP, hCTR1 is rapidly internalized through macropinocytosis and degraded by the proteasome. |
