Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
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Oxaliplatin is a clinical anticancer drug with a pharmacological profile distinct from that of cisplatin. Our studies compared site- and region-specificity of lesions induced by oxaliplatin and cisplatin in naked and intracellular DNA, respectively. Oxaliplatin adducts in naked Simian virus 40 (SV40 DNA) were mapped by repetitive primer extension. The sites of oxaliplatin adducts were nearly identical to the sites of cisplatin adducts and were focused in G clusters and GNG motifs probably reflecting intrastrand cross-links. Although alkaline agarose electrophoresis of specific SV40 fragments showed that oxaliplatin formed interstrand cross-links, the levels of this lesion type were low. Drug-induced lesions in discrete loci of cellular DNA were assessed by the polymerase chain reaction stop assay in human tumor A2780 cells. Oxaliplatin at 200 microM induced approximately 1300, approximately 1500, approximately 800, and approximately 300 lesions/10(6) bp in the human beta-globin, c-myc, and HPRT genes and in mitochondrial DNA, respectively. Cisplatin formed two to six times more lesions in the same regions. For both drugs, lesion frequencies seem to parallel the density of drug-binding motifs in the nuclear regions, whereas mitochondrial DNA was disproportionately less affected. Despite less potent induction of DNA lesions, oxaliplatin was more cytotoxic than cisplatin against A2780 cells. Because our findings clearly demonstrate that oxaliplatin forms covalent adducts with a similar sequence- and region-specificity to that of cisplatin, other properties of oxaliplatin adducts, factors other than DNA binding, or both determine the unique features of the mechanism of action of oxaliplatin.
Mol Pharmacol 1998 Nov
PMID:Sequence- and region-specificity of oxaliplatin adducts in naked and cellular DNA. 980 12

The partitioning and biotransformations of oxaliplatin [trans-l-1,2-diaminocyclohexaneoxalatoplatinum(II)] were investigated in the blood of Wistar male rats in vitro. [3-H]-Oxaliplatin was incubated with rat blood at 37 degrees C in 5% CO2 and the concentrations of all Pt complexes containing the [3-H]-dach carrier ligand were followed for up to 12 hours. Decay for both oxaliplatin and Pt-dach in the plasma ultrafiltrate (PUF) was rapid (t 1/2 oxaliplatin = 0.68 h and t 1/2 for Pt-dach in the PUF = 0.85 h). After 9 hours, the concentration of oxaliplatin fell below the detection limit. By 4 hours, the PUF-Pt-dach reached a plateau, which was 12% of total Pt-dach. The binding of Pt-dach to red blood cells (RBCs) and plasma proteins was also very rapid (t 1/2 RBCs = 0.58 h and t 1/2 plasma proteins = 0.78 h) and reached equilibrium by 4 hours. At equilibrium, 35% of total Pt-dach was bound to plasma proteins, 12% was in the plasma ultrafiltrate, and 53% was found associated with RBCs. Of the Pt-dach associated with RBCs, 23% was bound to the RBC membrane, 58% was bound to RBC cytosolic proteins, and 19% was in the RBC cytosol ultrafiltrate. Thus, these studies confirm previous observations of oxaliplatin accumulation by rat RBCs. To better characterize the determinants of this accumulation, oxaliplatin and other Pt-dach complexes were compared with respect to both their uptake by rat RBCs and their partition coefficients in octanol and water. The rank order for the rate of uptake was ormaplatin approximately Pt(dach)Cl2 > oxaliplatin > Pt(dach)(mal); while the rank order for hydrophobicity was ormaplatin > Pt(dach)Cl2 > Pt(dach)(mal) > oxaliplatin. Thus, in general, Pt-dach complexes appeared to be taken up better by RBCs than cisplatin or carboplatin, and the hydrophobicity of most of the Pt-dach complexes appeared to correlate with uptake. However, factors other than the dach carrier ligand and hydrophobicity clearly influence uptake. The biotransformations of oxaliplatin in rat blood were characterized utilizing reverse-phase high-pressure liquid chromatography (HPLC). In the RBC cytosol, both oxaliplatin and Pt(dach)Cl2 were observed at early times, while Pt(dach)(GSH)2, Pt(dach)(Cys)2, Pt(dach)(GSH), and free dach accumulated and reached steady-state levels by 4 hours. Thus, in the RBC cytosol, only chemically unreactive biotransformation products such as free dach and Pt-dach complexes with cysteine and glutathione accumulated in significant amounts. Furthermore, only Pt(dach)(Cys)2 and free dach appeared to efflux from RBCs. Thus, RBCs do not appear to serve as a reservoir for cytotoxic Pt-dach complexes. Finally, the biotransformation products of oxaliplatin in the plasma were identified as Pt(dach)Cl2, Pt(dach)(Cys)2, Pt(dach)(GSH), Pt(dach)(Met), Pt(dach)(GSH)2, and free dach. Among these compounds, Pt(dach)Cl2 formed transiently, while Pt(dach)(Cys)2, Pt(dach)(Met), and free dach accumulated and were the major biotransformation products by 4 hours. Thus, this study has identified the major inert and reactive biotransformation products of oxaliplatin in both plasma and RBCs and thus provides the information required for detailed pharmacokinetic and biotransformation studies of oxaliplatin. [figure in text]
J Biochem Mol Toxicol 1999
PMID:Biotransformations of oxaliplatin in rat blood in vitro. 1009 1

Damage to cellular DNA is believed to determine the antiproliferative properties of platinum (Pt) drugs. This study characterized DNA damage by oxaliplatin, a diaminocyclohexane Pt drug with clinical antitumor activity. Compared with cisplatin, oxaliplatin formed significantly fewer Pt-DNA adducts (e.g., 0.86+/-0.04 versus 1.36+/- 0.01 adducts/10(6) base pairs/10 microM drug/1 h, respectively, in CEM cells, P<.01). Oxaliplatin was found to induce potentially lethal bifunctional lesions, such as interstrand DNA cross-links (ISC) and DNA-protein cross-links (DPC) in CEM cells. As with total adducts, however, oxaliplatin produced fewer (P<.05) bifunctional lesions than did cisplatin: 0.7+/-0.2 and 1.8+/-0.3 ISC and 0.8+/-0.1 and 1.5+/-0.3 DPC/10(6) base pairs/10 microM drug, respectively, after a 4-h treatment. Extended postincubation (up to 12 h) did not compensate the lower DPC and ISC levels by oxaliplatin. ISC and DPC determinations in isolated CEM nuclei unequivocally verified that oxaliplatin is inherently less able than cisplatin to form these lesions. Reactivation of drug-treated plasmids, observed in four cell lines, suggests that oxaliplatin adducts are repaired with similar kinetics as cisplatin adducts. Oxaliplatin, however, was more efficient than cisplatin per equal number of DNA adducts in inhibiting DNA chain elongation ( approximately 7-fold in CEM cells). Despite lower DNA reactivity, oxaliplatin exhibited similar or greater cytotoxicity in several other human tumor cell lines (50% growth inhibition in CEM cells at 1.1/1.2 microM, respectively). The results demonstrate that oxaliplatin-induced DNA lesions, including ISC and DPC, are likely to contribute to the drug's biological properties. However, oxaliplatin requires fewer DNA lesions than does cisplatin to achieve cell growth inhibition.
Mol Pharmacol 2000 Nov
PMID:Oxaliplatin-induced damage of cellular DNA. 1104 38

Oxaliplatin, a diaminocyclohexane-containing platinum, has a spectrum of activity and mechanisms of action and resistance that appear to be different from those of other platinum-containing compounds, notably cisplatin. The first part of this review describes the differences between oxaliplatin and cisplatin in terms of their spectrum of activity and adduct formation and then goes on to discuss molecular and cellular experimental data that potentially explain them. Particular emphasis is placed on the differential role of DNA repair mechanisms. In addition, the anticancer effects of oxaliplatin are optimized when it is administered in combination with other anticancer agents, such as 5-fluorouracil, gemcitabine, cisplatin, or carboplatin; topoisomerase I inhibitors; and taxanes. In vitro and preclinical combination data that could optimize oxaliplatin-based chemotherapy are also reviewed.
Mol Cancer Ther 2002 Jan
PMID:Cellular and molecular pharmacology of oxaliplatin. 1246 17

Oxaliplatin (Eloxatine) is a third-generation platinum compound which has shown a wide antitumour effect both in vitro and in vivo, a better safety profile than cisplatin and a lack of cross-resistance with cisplatin and carboplatin. In this scenario, oxaliplatin may represent an innovative and challenging drug extending the antitumour activity in diseases such as gastrointestinal cancer that are not usually sensitive to these coordination complexes. Oxaliplatin has a non-hydrolysable diaminocyclohexane (DACH) carrier ligand which is maintained in the final cytotoxic metabolites of the drug. Like cisplatin, oxaliplatin targets DNA producing mainly 1,2-GG intrastrand cross-links. The cellular and molecular aspects of the mechanism of action of oxaliplatin have not yet been fully elucidated. However, the intrinsic chemical and steric characteristics of the DACH-platinum adducts appear to contribute to the lack of cross-resistance with cisplatin. To date, mismatch repair and replicative bypass appear to be the processes most likely involved in differentiating the molecular responses to these agents.
Cell Mol Life Sci 2002 Nov
PMID:Cellular and molecular aspects of drugs of the future: oxaliplatin. 1253 May 22

Oxaliplatin is a platinum-derived antitumor drug that is active against cisplatin-resistant tumors and has lower overall toxicity than does cisplatin. DNA adduct formation is believed to mediate the cytotoxic activity of both compounds; however, the adducts may also be responsible for mutagenic and secondary tumorigenic activities. In this study, we have compared the mutagenicity of oxaliplatin and cisplatin in the Hprt gene of CHO-K1 cells. Both drugs produced dose-related increases in mutant frequency. For 1-hr treatments, oxaliplatin was less mutagenic than cisplatin at equimolar doses, while similar mutant frequencies were induced at equitoxic doses. Sequencing of mutant Hprt genes indicated that the mutation spectra of both oxaliplatin and cisplatin were significantly different from the spontaneous mutation spectrum (P = 0.014 and P = 0.008, respectively). A significant difference was also observed between the spectra of oxaliplatin- and cisplatin-induced mutations (P = 0.033). Although G:C-->T:A transversion was the most common mutation produced by both compounds, oxaliplatin produced higher frequencies of A:T-->T:A transversion than did cisplatin, most commonly at nucleotide 307, and higher frequencies of small deletions/insertions. Also, cisplatin induced tandem base-pair substitutions, mainly at positions 135/136, and a higher frequency of G:C-->A:T transition than did oxaliplatin. These results provide the first evidence that oxaliplatin is mutagenic and that the profiles of cisplatin- and oxaliplatin-induced mutations display not only similarities but also distinctive features relating to the type and sequence-context preference for mutation. Environ.
Environ Mol Mutagen 2005 Aug
PMID:Comparative analysis of the mutagenic activity of oxaliplatin and cisplatin in the Hprt gene of CHO cells. 1588 15

Clinical studies have shown that oxaliplatin, a novel platinum derivative, is a potent chemotherapeutic agent for colorectal cancer when combined with 5-fluorouracil and leucovorin. Although the toxic activity is based on covalent adducts between platinum and DNA, its actual biological behavior is mostly unknown. In an effort to explore the mechanism of tumor susceptibility to oxaliplatin, we examined the cytotoxic effects of oxaliplatin in colorectal cancer cell lines in reference to p53 gene status. Although p53 gene status did not clearly predict sensitivity to oxaliplatin, p53 wild-type cells including HCT116 were sensitive but HCT116 p53-/- were found to be resistant to oxaliplatin. Oxaliplatin caused strong p21waf1/cip1 induction and G0-G1 arrest in p53 wild-type cells, whereas cisplatin did not induce G0-G1 arrest. Assays using p53 wild but p21waf1/cip1 null HCT116 cells revealed that oxaliplatin did not show G0-G1 arrest and reduced growth-inhibitory effects, suggesting that p21waf1/cip1 may be a key element in oxaliplatin-treated p53 wild-type cells. Although HCT116 is DNA mismatch repair-deficient, a mismatch repair-proficient HCT116+ch3 cell line displayed similar responses with regard to p21waf1/cip1-mediated growth inhibition and G0-G1 arrest. In p53 mutant cells, on the other hand, oxaliplatin caused an abrupt transition from G1 to S phase and eventually resulted in G2-M arrest. This abrupt entry into S phase was associated with loss of the p21waf1/cip1 protein via proteasome-mediated degradation. These findings suggest that p21waf1/cip1 plays a role in oxaliplatin-mediated cell cycle and growth control in p53-dependent and -independent pathways.
Mol Cancer Ther 2005 Oct
PMID:Role of p21waf1/cip1 in effects of oxaliplatin in colorectal cancer cells. 1622 9

To date, clinical studies combining the new generation of targeted therapies and chemotherapy have had mixed results. Preclinical studies can be used to identify potential antagonism/synergy between certain agents, with the potential to predict the most efficacious combinations for further investigation in the clinical setting. In this study, we investigated the sequence-dependent interactions of ZD6474 with oxaliplatin in two human colon cell lines in vitro. We evaluated the in vitro antitumor activity of ZD6474, an inhibitor of vascular endothelial growth factor receptor (VEGFR), epidermal growth factor receptor (EGFR) and RET tyrosine kinase activity, and oxaliplatin using three combination schedules: ZD6474 before oxaliplatin, oxaliplatin before ZD6474, and concurrent exposure. Cell proliferation studies showed that treatment with oxaliplatin followed by ZD6474 was highly synergistic, whereas the reverse sequence was clearly antagonistic as was concurrent exposure. Oxaliplatin induced a G(2)-M arrest, which was antagonized if the cells were previously or concurrently treated with ZD6474. ZD6474 enhanced oxaliplatin-induced apoptosis but only when added after oxaliplatin. The sequence-dependent antitumor effects appeared, in part, to be based on modulation of compensatory prosurvival pathways. Thus, expression of total and active phosphorylated EGFR, as well as AKT and extracellular signal-regulated kinase, was markedly increased by oxaliplatin. This increase was blocked by subsequent treatment with ZD6474. Furthermore, the synergistic sequence resulted in reduced expression of insulin-like growth factor-I receptor and a marked reduction in secretion of vascular endothelial growth factor protein. ZD6474 in combination with oxaliplatin has synergistic antiproliferative properties in human colorectal cancer cell lines in vitro when oxaliplatin is administered before ZD6474.
Mol Cancer Ther 2006 Jul
PMID:Sequence-dependent inhibition of human colon cancer cell growth and of prosurvival pathways by oxaliplatin in combination with ZD6474 (Zactima), an inhibitor of VEGFR and EGFR tyrosine kinases. 1689 75

Oxaliplatin (Eloxatin) is a third-generation platinum derivative with an in vitro and in vivo spectrum of activity distinct from that of cisplatin, especially in colon cancer cells. Here, we studied the molecular basis of this difference on the HCT-116 human colon carcinoma cell line (mismatch repair-deficient, wild-type functional p53). Oxaliplatin inhibited HCT-116 cell proliferation with greater efficacy than cisplatin. At comparable concentrations, cisplatin slowed down the replication phase and activated the G2-M checkpoint, whereas oxaliplatin activated the G1-S checkpoint and completely blocked the G2-M transition. With the aim of finding oxaliplatin-specific target genes and mechanisms differing from those of cisplatin, we established the transcriptional signatures of both products on HCT-116 cells using microarray technology. Based on hierarchical clustering, we found that (a) many more genes were modulated by oxaliplatin compared with cisplatin and (b) among the 117 modulated genes, 79 were regulated similarly by both drugs and, in sharp contrast, 38 genes were dose dependently down-regulated by oxaliplatin and, conversely, up-regulated or unaffected by cisplatin. Interestingly, several cell cycle-related genes encoding proteins involved in DNA replication and G2-M progression belong to this latter group. RNA modulations, confirmed at the protein level, were in accordance with oxaliplatin- and cisplatin-induced cell cycle variations. Beyond the identification of genes affected by both drugs, the identified oxaliplatin-specific target genes could be useful as predictive markers for evaluating and comparing the efficacy and molecular pharmacology of platinum drugs.
Mol Cancer Ther 2006 Sep
PMID:Repression of cell cycle-related proteins by oxaliplatin but not cisplatin in human colon cancer cells. 1698 47

Vascular endothelial growth factor (VEGF) is induced by stress. We determined whether chemotherapy (genotoxic stress) could induce expression of VEGF and VEGF receptors (VEGFR) in human colorectal cancer cells. The colorectal cancer cell lines HT29, RKO, and HCT116 were acutely exposed to increasing doses of oxaliplatin or 5-fluorouracil for 2, 6, and 24 h in vitro. Expression of VEGF ligand family members, VEGFRs, and signaling intermediates was determined by reverse transcription-PCR and Northern and Western blotting. The effect of oxaliplatin on VEGF-A transcriptional activity was determined by promoter assays. Acute exposure of human colorectal cancer cells to oxaliplatin led to a marked induction of VEGF-A mRNA and protein, whereas 5-fluorouracil alone or when added to oxaliplatin did not cause a further increase in VEGF levels. VEGF-A promoter activity was induced by oxaliplatin exposure. Expression of VEGF-C, placental growth factor, VEGFR-1, and neuropilin-1 levels were also increased when cells were treated with oxaliplatin. Oxaliplatin led to an increase in Akt and Src activation in HT29 cells. In contrast, Akt activation did not change in RKO cells whereas phospho-Src and phospho-p44/42 mitogen-activated protein kinase was dramatic increased by oxaliplatin. Inhibition of Akt or Src activation with wortmannin or PP2 blocked induction of VEGF-A by oxaliplatin in HT29 or RKO cells, respectively. VEGFRs may reflect the adaptive stress responses by which tumor cells attempt to protect themselves from genotoxic stress. Neutralization of prosurvival responses with anti-VEGF therapy might explain, in part, some of the beneficial effects of anti-VEGF therapy when added to chemotherapy.
Mol Cancer Ther 2008 Sep
PMID:Effect of chemotherapeutic stress on induction of vascular endothelial growth factor family members and receptors in human colorectal cancer cells. 1879 Jul 86


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