Antiproliferative activity of clausine E, mukonine, and koenoline bioisosteres
1–
3 was evaluated against miscellaneous cancer cell lines and compared to those obtained with clausine E and mukonine.
...Aza-analogues of clausine E, mukonine and koenoline were prepared from 1-(benzenesulfonyl)-1
H-pyrrolo2,3-
bpyridine-3-carboxaldehyde and their antiproliferative activity was evaluated against miscellaneous cancer cell lines and compared to those obtained with clausine E and mukonine.
We have investigated the target and mechanism of action of a new family of cytotoxic small molecules of marine origin. PM050489 and its dechlorinated analogue PM060184 inhibit the growth of relevant ...cancer cell lines at subnanomolar concentrations. We found that they are highly potent microtubule inhibitors that impair mitosis with a distinct molecular mechanism. They bind with nanomolar affinity to unassembled αβ-tubulin dimers, and PM050489 binding is inhibited by known Vinca domain ligands. NMR TR-NOESY data indicated that a hydroxyl-containing analogue, PM060327, binds in an extended conformation, and STD results define its binding epitopes. Distinctly from vinblastine, these ligands only weakly induce tubulin self-association, in a manner more reminiscent of isohomohalichondrin B than of eribulin. PM050489, possibly acting like a hinge at the association interface between tubulin heterodimers, reshapes Mg2+-induced 42 S tubulin double rings into smaller 19 S single rings made of 7 ± 1 αβ-tubulin dimers. PM060184-resistant mutants of Aspergillus nidulans map to β-tubulin Asn100, suggesting a new binding site different from that of vinblastine at the associating β-tubulin end. Inhibition of assembly dynamics by a few ligand molecules at the microtubule plus end would explain the antitumor activity of these compounds, of which PM060184 is undergoing clinical trials.
Factors that reduce the intracellular concentration of triphosphorylated cytarabine (ara‐CTP), the active form of cytarabine (ara‐C), may induce chemoresistance in acute myeloid leukaemia (AML) ...patients. These factors include reduced influx of ara‐C by the hENT1 transporter, reduced phosphorylation by deoxycytidine kinase (dCK), and increased degradation by high Km cytoplasmic 5′‐nucleotidase (5NT) and/or cytidine deaminase (CDD). Increased levels of DNA polymerase α (DNA POL) and reduced levels of topoisomerase I (TOPO I) and topoisomerase II (TOPO II) have also been detected in ara‐C‐resistant cell lines. To determine whether these factors are implicated in clinical ara‐C resistance, we analysed the expression of these parameters at diagnosis, using reverse transcription polymerase chain reaction, in the blast cells of 123 AML patients treated with ara‐C. At diagnosis, hENT1, dCK, CDD, 5NT, TOPO I, TOPO II, DNA POL and MDR1 were expressed in 83%, 22%, 7%, 37%, 59%, 37%, 39% and 16% of patients respectively. In univariate analysis, patients with expression of 5NT or DNA POL at diagnosis had significantly shorter disease‐free survival (DFS). In multivariate analysis, DNA POL positivity and hENT1 deficiency were related to a shorter DFS. In univariate analysis, patients with 5NT‐positive blasts had significantly shorter overall survival (OS). In multivariate analysis, shorter OS was related to DNA POL positivity. These results suggest that expression of DNA POL, 5NT and hENT1 at diagnosis may be resistance mechanisms to ara‐C in AML patients.
The therapeutic efficiency of anticancer nucleoside analogues (NA) strongly depends on their intracellular accumulation and conversion into 5'-triphosphates. Because active NATP cannot be directly ...administrated due to instability, we present here a strategy of nanoencapsulation of these active drugs for efficient delivery to tumors. Stable lyophilized formulations of 5'-triphosphates of cytarabine (araCTP), gemcitabine (dFdCTP), and floxuridine (FdUTP) encapsulated in biodegradable PEG-cl-PEI or F127-cl-PEI nanogel networks (NGC and NGM, respectively) were prepared by a self-assembly procedure. Cellular penetration, in vitro cytotoxicity, and drug-induced cell cycle perturbations of these nanoformulations were analyzed in breast and colorectal cancer cell lines. Cellular accumulation and NATP release from nanogel was studied by confocal microscopy and direct high-performance liquid chromatography analysis of cellular lysates. Antiproliferative effect of dFdCTP nanoformulations was evaluated in human breast carcinoma MCF7 xenograft animal model. Nanoencapsulated araCTP, dFdCTP, and FdUTP showed similar to NA cytotoxicity and cell cycle perturbations. Nanogels without drugs showed very low cytotoxicity, although NGM was more toxic than NGC. Treatment by NATP nanoformulations induced fast increase of free intracellular drug concentration. In human breast carcinoma MCF7 xenograft animal model, i.v. dFdCTP-nanogel was equally effective in inhibiting tumor growth at four times lower administered drug dose compared with free gemcitabine. Active triphosphates of NA encapsulated in nanogels exhibit similar cytotoxicity and cell cycle perturbations in vitro and faster cell accumulation and equal tumor growth-inhibitory activity in vivo at much lower dose compared with parental drugs, illustrating their therapeutic potential for cancer chemotherapy.
Resistance to fludarabine is observed in the clinic, and molecular predictive assays for benefit from chemotherapy are required. Our objective was to determine if expression of nucleoside transport ...and metabolism genes was associated with response to fludarabine therapy in patients with chronic lymphocytic leukemia (CLL). CLL cells from 56 patients were collected prior to treatment with fludarabine. Quantitative reverse transcriptase–polymerase chain reaction (RT-PCR) was performed on sample RNA to determine the relative levels of mRNA of 3 nucleoside transporters that mediate fludarabine uptake (human equilibrative nucleoside transporter 1 hENT1, human equilibrative nucleoside transporter 2 hENT2, and human concentrative nucleoside transporter 3 hCNT3), deoxycytidine kinase (dCK), and 3 5′-nucleotidases (ecto-5′nucleotidase CD73, deoxynucleotidase-1 dNT-1, and cytoplasmic high-Km 5-nucleotidase CN-II). Two-dimensional hierarchical cluster analysis of gene expression identified 2 distinct populations of CLL. Cluster 2 patients experienced a 3.4-fold higher risk of disease progression than cluster 1 patients (P = .0058, log-rank analysis). Furthermore, independent analysis of the individual genes of interest revealed statistically significant differences for risk of disease progression (adjusted hazard ratios HRs) with underexpression of dNT-1 (HR = 0.45; P = .042), CD73 (HR = 0.40; P = .022), and dCK (HR = 0.0.48; P = .035), and overexpression of hCNT3 (HR = 4.7; P = .0007) genes. Subjects with elevated hCNT3 expression experienced a lower complete response rate to fludarabine therapy (11% vs 69%; P = .002). No hCNT3-mediated plasma membrane nucleoside transport was detected in CLL samples expressing hCNT3 message, and hCNT3 protein was localized to the cytoplasm with immunohistochemical and confocal microscopy.
Background and Purpose
We have previously shown that cells with a defective Fanconi anaemia (FA) pathway are hypersensitive to trabectedin, a DNA‐binding anti‐cancer tetrahydroisoquinoline (DBAT) ...whose adducts functionally mimic a DNA inter‐strand cross link (ICL). Here we expand these observations to new DBATs and investigate whether our findings in primary untransformed cells can be reproduced in human cancer cells.
Experimental Approach
Initially, the sensitivity of transformed and untransformed cells, deficient or not in one component of the FA pathway, to mitomycin C (MMC) and three DBATs, trabectedin, Zalypsis and PM01183, was assessed. Then, the functional interaction of these drugs with the FA pathway was comparatively investigated.
Key Results
While untransformed FA‐deficient haematopoietic cells were hypersensitive to both MMC and DBATs, the response of FA‐deficient squamous cell carcinoma (SCC) cells to DBATs was similar to that of their respective FA‐competent counterparts, even though these FA‐deficient SCC cells were hypersensitive to MMC. Furthermore, while MMC always activated the FA pathway, the DBATs inhibited the FA pathway in the cancer cell lines tested and this enhanced their response to MMC.
Conclusions and Implications
Our data show that although DBATs functionally interact with DNA as do agents that generate classical ICL, these drugs should be considered as FA pathway inhibitors rather than activators. Moreover, this effect was most significant in a variety of cancer cells. These inhibitory effects of DBATs on the FA pathway could be exploited clinically with the aim of ‘fanconizing’ cancer cells in order to make them more sensitive to other anti‐tumour drugs.
To determine whether the human equilibrative nucleoside transporter 1 (hENT1), deoxycytidine kinase (dCK), cytoplasmic 5′-nucleotidase (5NT), cytidine deaminase (CDD), topoisomerase I (TOPO I) and ...topoisomerase II α (TOPO II) are involved in clinical resistance to cytarabine (ara-C), we analyzed the level of expression of these parameters by reverse transcriptase polymerase chain reaction (rt-PCR), at diagnosis in the blast cells of 77 acute myeloid leukemia (AML) patients treated with ara-C, including 31 for whom samples were collected at first relapse. By univariate and/or multivariate analyses, patients with expression of 5NT or hENT1 deficiency at diagnosis had significantly shorter disease-free survival (DFS) and overall survival (OS). These results suggest that expression of 5NT and reduced hENT1 in leukemic blasts at diagnosis are correlated with clinical outcome and may play a role in resistance mechanisms to ara-C in patients with AML.
The pyrazolo1,5-
a-1,3,5-triazine derivatives
1a–
c constitute a new series of tubulin inhibitors and displayed micromolar antiproliferative activities towards colorectal cancer cell lines.
...Pyrazolo1,5-
a-1,3,5-triazine myoseverin derivatives
1a–c were prepared from 4-(
N-methyl-
N-phenylamino)-2-methylsulfanylpyrazolo1,5-
a-1,3,5-triazine
2. Their cytotoxic activity, inhibition of tubulin polymerization, and cell cycle effects were evaluated. Compounds
1a and
1c are potent tubulin inhibitors and displayed specific antiproliferative activity in colorectal cancer cell lines at micromolar concentrations.
Abstract Objective This study investigated the relationship between 13 proteins involved in DNA damage and the outcomes of patients with recurrent ovarian cancer (ROC). Patients and methods ...Immunohistochemistry staining was performed in 114 diagnostic samples from patients with serous ROC who participated in the OVA-301 study, which compared pegylated liposomal doxorubicin (PLD) with a combination of trabectedin plus PLD. Percentage of positive cells for every marker was calculated and correlated with overall response rate (ORR), progression-free survival (PFS) and overall survival (OS). Results A statistically significant correlation between high levels of nibrin and lower ORR ( P = 0.03), shorter PFS ( P = 0.007) and shorter OS ( P = 0.01) was observed. After stratification, in patients with platinum-sensitive disease treated with the combination of trabectedin plus PLD, high levels of nibrin correlated with lower ORR ( P = 0.01) and shorter PFS ( P = 0.02). A better clinical outcome (ORR, PFS and OS) was also associated to low levels of CHK2 in trabectedin plus PLD treated patients. No correlations were found in PLD-treated patients. According to the results of a multivariate analysis, there was a statistically significant correlation between high nibrin ( P = 0.001) and low BRCA2 levels ( P = 0.03) and a worse PFS, and between high nibrin levels and a worse OS ( P = 0.006). Conclusion Our results indicate that high nibrin expression seems to be associated with a worse clinical outcome in serous ROC, particularly in patients treated with the combination trabectedin plus PLD. Prospective studies to determine clinical usefulness of nibrin as a possible biomarker in other series of patients with ROC are warranted.
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