Preclinical studies have indicated that there is only partial cross-resistance between cisplatin and oxaliplatin. The molecular background for this is incompletely known. To investigate the differences in resistance, we rendered a colon cancer cell line (S1) resistant against cisplatin and oxaliplatin and characterized the subclones with regard to cross-resistance, platinum uptake, and gene expression profiles. Four oxaliplatin and four cisplatin-resistant cell lines were produced from S1 by step-wise increasing the concentrations of the drugs in the growth medium. Cytotoxicity was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and platinum accumulation in cell lysates and DNA preparations by inductively coupled plasma mass spectroscopy. Gene expression was investigated by cDNA microarrays. The protein expression of the ATP-binding cassette B1 (ABCB1) was measured by immunohistochemistry. The cisplatin-resistant cell lines were 1.5-6.2-fold resistant against cisplatin and the oxaliplatin-resistant sublines 2.6-17-fold resistant against oxaliplatin. There was a limited degree of cross-resistance. Oxaliplatin resistance could be explained to a larger degree by reduced drug accumulation whereas mechanisms for increased tolerance against platinum incorporation in DNA seemed to be of higher importance for resistance against cisplatin. A greater number of ABC transporters were upregulated in the oxaliplatin-resistant cell lines compared with those selected for cisplatin resistance. ABCB1 was highly overexpressed in the three most oxaliplatin-resistant sublines, but significantly underexpressed in the two most cisplatin-resistant cell lines. This was also confirmed by immunohistochemistry. However, functional tests did not show any increase in ABCB1 transport activity in the oxaliplatin-resistant sub-lines compared with S1.
"To estimate cell recovery after TCDD pretreatment, cell viability was measured by MTT- and MTS-based cell proliferation assays depending on cell type (21). For the MTT assay, the medium was removed from each well and replaced with 1 mL of fresh medium, containing 100 µL of 5 mg/mL MTT solution. "
[Show abstract][Hide abstract] ABSTRACT: 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can induce drug transporter genes such as the ATP-binding cassette G member 2 (ABCG2), which contributes to multidrug resistance. We investigated the effect of TCDD pretreatment on drug transporters induction from cancer cells of various origins. Cell viabilities after treatment of cisplatin were measured to evaluate acquiring cisplatin resistance by TCDD. Acquring cisplatin resistance was found only in cisplatin senstivie cancer cells including gastric SNU601, colon LS180, brain CRT-MG and lymphoma Jurkat cells which showed a significant increase in cell viability after combined treatment with TCDD and cisplatin. High increase of ABCG2 gene expression was found in SNU601 and LS180 cells with a mild increase in the expression of the ABCC3, ABCC5,and SLC29A2 genes in SNU601 cells, and of major vault protein (MVP) in LS180 cells. The AhR inhibitor kaempferol suppressed the upregulation of ABCG2 expression and reversed the TCDD-induced increase in cell viability in LS180 cells. However, in CRT-MG cells, other transporter genes including ABCC1, ABCC5, ABCA3, ABCA2, ABCB4, ABCG1, and SLC29A1 were up-regulated. These findings suggested the acquiring cisplatin resistance by TCDD associated with cancer cell-type-specific induction of drug transporters.
Journal of Korean Medical Science 09/2014; 29(9):1188-98. DOI:10.3346/jkms.2014.29.9.1188 · 1.27 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: One of the major limitations of chemotherapy is that often, over time, tumor cells become either inherently resistant or develop multidrug resistance to the treatment. Another limitation of chemotherapy is toxicity to normal tissues and adverse side effects. The reasons for the failure of some cancers to respond to chemotherapeutic drugs are not clear but have been attributed to alterations in many molecular pathways, which include drug metabolizing enzymes and drug transporter genes. Alterations in the energy-dependent ATP-binding cassette (ABC) transporter genes have been suggested to confer a drug-resistant phenotype by decreasing the intracellular accumulation of chemotherapeutic drugs via efflux mechanisms. In addition, polymorphisms in UDP-glucuronosyltransferases (UGTs) have been reported to correlate with clinical outcome and drug resistance. In this review, we provide an overview of known polymorphisms within UGTs and ABC transporter genes that have been reported to have altered expression and/or activity in breast cancer. Those polymorphic variants that affect the clinical efficacy and confer drug resistance of chemotherapeutic agents, including hormonal therapies, taxanes, anthracyclines, and alkylating agents, in breast cancer.
[Show abstract][Hide abstract] ABSTRACT: Oxaliplatin is a third-generation platinum drug that has favorable activity in cisplatin-resistant cells. However, the molecular mechanisms underlying oxaliplatin resistance are not well understood. To investigate the molecular mechanisms involved, resistant cell lines were independently derived from colon cancer (DLD1) and bladder cancer (T24) cells. Oxaliplatin-resistant DLD1 OX1 and DLD1 OX2 cell lines were approximately 16.3-fold and 17.8-fold more resistant to oxaliplatin than the parent cell lines, respectively, and had 1.7- and 2.2-fold higher cross-resistance to cisplatin, respectively. Oxaliplatin-resistant T24 OX2 and T24 OX3 cell lines were approximately 5.0-fold more resistant to oxaliplatin than the parent cell line and had 1.9-fold higher cross-resistance to cisplatin. One hundred and fifty-eight genes commonly upregulated in both DLD1 OX1 and DLD1 OX2 were identified by microarray analysis. These genes were mainly involved in the function of transcriptional regulators (14.6%), metabolic molecules (14.6%), and transporters (9.5%). Of these, nuclear factor I/B (NFIB) was upregulated in all oxaliplatin-resistant cells. Downregulation of NFIB rendered cells sensitive to oxaliplatin, but not to cisplatin. Forced expression of NFIB induced resistance to oxaliplatin, but not to cisplatin. Taken together, these results suggest that NFIB is a novel and specific biomarker for oxaliplatin resistance in human cancers.
Cancer Science 10/2010; 102(2):382-6. DOI:10.1111/j.1349-7006.2010.01784.x · 3.52 Impact Factor
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