Purpose: The aim of this study is to examine the factors affecting sensitivity to cisplatin, carboplatin, and oxaliplatin in human colorectal tumor cell lines.
Methods: Caco-2, DLD-1, HCT-15, HCT116, LS180, SW620, and WiDr cells were used. Their growth inhibition by platinum derivatives was evaluated with a WST-1 assay utilizing succinate dehydrogenase activity. Cellular accumulation and DNA-binding of platinum were measured with an inductively coupled plasma mass spectrometer. The mRNA levels of copper transporters (hCtr1, ATP7A, and ATP7B) and organic cation transporters (hOCT1, hOCT2, and hOCT3) were evaluated by the real-time reverse transcription-PCR method using SYBR green.
Results: The cytotoxicity of platinum derivatives ranked oxaliplatin > cisplatin > carboplatin in almost all cells used. Cellular accumulation and DNA-binding of platinum varied among the types of cells, but levels were similar on treatment with cisplatin and oxaliplatin, and lower in response to carboplatin. The levels of copper and organic cation transporter mRNAs also differed with cell type. A correlation analysis revealed that sensitivity to platinum derivatives was dependent in part on the amount of platinum bound to DNA. In addition, the cellular accumulation of platinum and level of ATP7A mRNA may be factors affecting the cytotoxicity of cisplatin, while the cytotoxicity of oxaliplatin was suggested to be affected by the levels of ATP7A and hOCT1 mRNAs.
Conclusion: Some factors affecting the sensitivity of tumor cells to platinum derivatives were proposed, and will provide useful information for cancer chemotherapy with platinum derivatives.