Cytogenetic characterization of chromosomal rearrangement in a human vinblastine-resistant CEM cell line: use of comparative genomic hybridization and fluorescence in situ hybridization

Design, synthesis and biological evaluation of new 2,6-difluorinated phenyl 4-(2-oxoimidazolidin-1-yl)benzenesulfonates as new antimicrotubule agents

We previously discovered a novel family of antimicrotubule agents designated as phenyl 4-(2-oxoimidazolidin-1-yl)benzenesulfonates (PIB-SOs). In this study, we evaluated the effect of the difluorination of the aromatic ring bearing the imidazolidin-2-one moiety (ring A) at positions 3, 5 and 2, 6 on their antiproliferative activity on four cancer cell lines, their ability to disrupt the microtubules and their toxicity toward chick embryos. We thus synthesized, characterized and biologically evaluated 24 new difluorinated PIB-SO derivatives designated as phenyl 3,5-difluoro-4-(2-oxoimidazolidin-1-yl)benzenesulfonates (3,5-PFB-SOs, 4-15) and phenyl 2,6-difluoro-4-(2-oxoimidazolidin-1-yl)benzenesulfonates (2,6-PFB-SOs, 16-27). The concentration of the drug required to inhibit cell growth by 50% (IC50) of 3,5-PFB-SOs is over 1000 nM while most of 2,6-PFB-SOs exhibit IC50 in the nanomolar range (23-900 nM). Furthermore, the most potent 2,6-PFB-SOs 19, 26 and 27 arrest the cell cycle progression in G2/M phase, induce cytoskeleton disruption and impair microtubule polymerization. Docking studies also show that the most potent 2,6-PFB-SOs 19, 21, 24, 26 and 27 have binding affinity toward the colchicine-binding site (C-BS). Moreover, their antiproliferative activity is not affected by antimicrotubule- and multidrug-resistant cell lines. Besides, they exhibit improved in vitro hepatic stability in the mouse, rat and human microsomes compared to their non-fluorinated counterparts. They also showed theoretical pharmacokinetic, physicochemical and drug-like properties suited for further in vivo assays. In addition, they exhibit low to no systemic toxicity toward chick embryos. Finally, our study evidences that PIB-SOs must be fluorinated in specific positions on ring A to maintain both their antiproliferative activity and their biological activity toward microtubules.

Resistance to Targeted Agents Used to Treat Paediatric ALK-Positive ALCL

Simple Summary

In general, the non-Hodgkin lymphoma (NHL), anaplastic large cell lymphoma (ALCL) diagnosed in childhood has a good survival outcome when treated with multi-agent chemotherapy. However, side effects of treatment are common, and outcomes are poorer after relapse, which occurs in up to 30% of cases. New drugs are required that are more effective and have fewer side effects. Targeted therapies are potential solutions to these problems, however, the development of resistance may limit their impact. This review summarises the potential resistance mechanisms to these targeted therapies.

Abstract

Non-Hodgkin lymphoma (NHL) is the third most common malignancy diagnosed in children. The vast majority of paediatric NHL are either Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL), anaplastic large cell lymphoma (ALCL), or lymphoblastic lymphoma (LL). Multi-agent chemotherapy is used to treat all of these types of NHL, and survival is over 90% but the chemotherapy regimens are intensive, and outcomes are generally poor if relapse occurs. Therefore, targeted therapies are of interest as potential solutions to these problems. However, the major problem with all targeted agents is the development of resistance. Mechanisms of resistance are not well understood, but increased knowledge will facilitate optimal management strategies through improving our understanding of when to select each targeted agent, and when a combinatorial approach may be helpful. This review summarises currently available knowledge regarding resistance to targeted therapies used in paediatric anaplastic lymphoma kinase (ALK)-positive ALCL. Specifically, we outline where gaps in knowledge exist, and further investigation is required in order to find a solution to the clinical problem of drug resistance in ALCL.

Preparation and biological evaluation of new antimicrotubule agents: Modification of the imidazolidin-2-one moiety of phenyl 4-(2-oxoimidazolidin-1-yl)benzenesulfonates

We prepared and biologically evaluated 32 novel molecules named phenyl 4-(dioxoimidazolidin-1-yl)benzenesulfonates (PID-SOs) and ethyl 2-(3-(4-(phenoxysulfonyl)phenyl)ureido)acetates (EPA-SOs). The antiproliferative activity of PID-SOs and EPA-SOs was assessed on four cancer cell lines (HT-1080, HT-29, M21, and MCF7). The most potent PID-SOs bearing an imidazolidin-2,4-dione group show antiproliferative activity in the nanomolar to low micromolar range (0.066 - 6 µM) while EPA-SOs and PID-SOs bearing an imidazolidin-2,5-dione moiety are mostly not active, exhibiting antiproliferative activity over 100 µM. The most potent PID-SOs (16-18) arrest the cell cycle progression in G2/M phase and interact with the colchicine-binding site leading to the microtubule and cytoskeleton disruption. Moreover, their antiproliferative activity is not impaired in vinblastine-, paclitaxel-, and multidrug-resistant cell lines. Finally, our study confirms that PID-SOs bearing the imidazolidin-2,4-dione moiety are a new family of promising antimitotics.

Genomic and transcriptomic profiling of resistant CEM/ADR-5000 and sensitive CCRF-CEM leukaemia cells for unravelling the full complexity of multi-factorial multidrug resistance

We systematically characterised multifactorial multidrug resistance (MDR) in CEM/ADR5000 cells, a doxorubicin-resistant sub-line derived from drug-sensitive, parental CCRF-CEM cells developed in vitro. RNA sequencing and network analyses (Ingenuity Pathway Analysis) were performed. Chromosomal aberrations were identified by array-comparative genomic hybridisation (aCGH) and multicolour fluorescence in situ hybridisation (mFISH). Fifteen ATP-binding cassette transporters and numerous new genes were overexpressed in CEM/ADR5000 cells. The basic karyotype in CCRF-CEM cells consisted of 47, XX, der(5)t(5;14) (q35.33;q32.3), del(9) (p14.1), +20. CEM/ADR5000 cells acquired additional aberrations, including X-chromosome loss, 4q and 14q deletion, chromosome 7 inversion, balanced and unbalanced two and three way translocations: t(3;10), der(3)t(3;13), der(5)t(18;5;14), t(10;16), der(18)t(7;18), der(18)t(21;18;5), der(21;21;18;5) and der(22)t(9;22). CCRF-CEM consisted of two and CEM/ADR5000 of five major sub-clones, indicating genetic tumor heterogeneity. Loss of 3q27.1 in CEM/ADR5000 caused down-regulation of ABCC5 and ABCF3 expression, Xq28 loss down-regulated ABCD1 expression. ABCB1, the most well-known MDR gene, was 448-fold up-regulated due to 7q21.12 amplification. In addition to well-known drug resistance genes, numerous novel genes and genomic aberrations were identified. Transcriptomics and genetics in CEM/AD5000 cells unravelled a range of MDR mechanisms, which is much more complex than estimated thus far. This may have important implications for future treatment strategies.

New platinum(II) complexes conjugated at position 7α of 17β-acetyl-testosterone as new combi-molecules against prostate cancer: design, synthesis, structure-activity relationships and biological evaluation

Prostate cancer is a major public health problem worldwide and, more specifically, new treatments for hormone-refractory cancers are highly sought by several research groups. Although platinum(II)-based chemotherapy and other strategies grow in interest to treat castration-resistant prostate cancer (CRPC), they still exhibit modest activity on CRPC and overall patient survival. In this study, we designed and prepared new combi-molecules using 17β-acetyl-testosterone and amino acid platinum(II) complexes linked at the position 7α to target and to improve the antiproliferative activity of platinum(II)-based chemotherapy on prostate cancer cells. Twelve chemical intermediates and six new combi-molecules were prepared and characterized. Structure-activity relationships studies show that the platinum complex moiety is essential for an optimal cytocidal activity. Moreover, stereochemistry of the amino acid involved in the platinum complexes had only minor effects on the antiproliferative activity whereas pyridinyl (10a and b) and thiazolyl (10f) complexes exhibited the highest cytocidal activities that are significantly superior to that of cisplatin used as control on human prostate adenocarcinoma LNCaP (AR+), PC3 (AR-) and DU145 (AR-). Compounds 10a, b and f arrested the cell cycle progression in S-phase and induced double strand breaks as confirmed by the phosphorylation of histone H2AX into γH2AX. Compounds 10a and f showed 33 and 30% inhibition, respectively of the growth of HT-1080 tumors grafted onto chick chorioallantoic membranes. Finally, compounds 10a and 10f exhibited low toxicity on the chick embryos (18 and 21% of death, respectively), indicating that these new combi-molecules might be a promising new class of anticancer agents for prostate cancer.

DNA Binding Studies of Vinca Alkaloids: Experimental and Computational Evidence

Fluorescence studies on the indole alkaloids vinblastine sulfate, vincristine sulfate, vincamine and catharanthine have demonstrated the DNA binding ability of these molecules. The binding mode of these molecules in the minor groove of DNA is non-specific. A new parameter of the purine-pyrimidine base sequence specificty was observed in order to define the non-specific DNA binding of ligands. Catharanthine had shown ‘same’ pattern of ‘Pu-Py’ specificity while evaluating its DNA binding profile. The proton resonances of a DNA decamer duplex were assigned. The models of the drug:DNA complexes were analyzed for DNA binding features. The effect of temperature on the DNA binding was also evaluated.

Substituted phenyl 4-(2-oxoimidazolidin-1-yl)benzenesulfonamides as antimitotics. Antiproliferative, antiangiogenic and antitumoral activity, and quantitative structure-activity relationships

The importance of the bridge linking the two phenyl moieties of substituted phenyl 4-(2-oxoimidazolidin-1-yl)benzenesulfonates (PIB-SOs) was assessed using a sulfonamide group, which is a bioisostere of sulfonate and ethenyl groups. Forty one phenyl 4-(2-oxoimidazolidin-1-yl)benzenesulfonamide (PIB-SA) derivatives were prepared and biologically evaluated. PIB-SAs exhibit antiproliferative activities at the nanomolar level against sixteen cancer cell lines, block the cell cycle progression in G(2)/M phase, leading to cytoskeleton disruption and anoikis. These results were subjected to CoMFA and CoMSIA analyses to establish quantitative structure-activity relationships. These results evidence that the sulfonate and sulfonamide moieties are reciprocal bioisosteres and that phenylimidazolidin-2-one could mimic the trimethoxyphenyl moiety found in the structure of numerous potent antimicrotubule agents. Finally, compounds 16 and 17 exhibited potent antitumor and antiangiogenic activities on HT-1080 fibrosarcoma cells grafted onto chick chorioallantoic membrane similar to CA-4 without significant toxicity for the chick embryos, making this class of compounds a promising class of anticancer agents.

Design, synthesis, biological evaluation, and structure-activity relationships of substituted phenyl 4-(2-oxoimidazolidin-1-yl)benzenesulfonates as new tubulin inhibitors mimicking combretastatin A-4

Sixty-one phenyl 4-(2-oxoimidazolidin-1-yl)benzenesulfonates (PIB-SOs) and 13 of their tetrahydro-2-oxopyrimidin-1(2H)-yl analogues (PPB-SOs) were prepared and biologically evaluated. The antiproliferative activities of PIB-SOs on 16 cancer cell lines are in the nanomolar range and unaffected in cancer cells resistant to colchicine, paclitaxel, and vinblastine or overexpressing the P-glycoprotein. None of the PPB-SOs exhibit significant antiproliferative activity. PIB-SOs block the cell cycle progression in the G₂/M phase and bind to the colchicine-binding site on β-tubulin leading to cytoskeleton disruption and cell death. Chick chorioallantoic membrane tumor assays show that compounds 36, 44, and 45 efficiently block angiogenesis and tumor growth at least at similar levels as combretastatin A-4 (CA-4) and exhibit low to very low toxicity on the chick embryos. PIB-SOs were subjected to CoMFA and CoMSIA analyses to establish quantitative structure–activity relationships.

Amplification of the ABCB1 region accompanied by a short sequence of 200bp from chromosome 2 in lung cancer cells

Lung cancer sublines No15-80-1 and No15-80-6 were selected by treatment of cell line NCI-H460 with paclitaxel at stepwise increasing concentrations from 50 nmol/L to 800 nmol/L. The two sublines exhibited amplifications of the ABCB1 region (previously MDR1) with different copy number profiles, but shared a common amplification pattern, which has been observed in amplification mediated by the breakage-fusion-bridge (BFB) cycle. Sequence analysis of the distal ends of the amplified regions, which were probably generated in a break-and-fusion of the initial round of the BFB cycle, revealed a head-to-head fused sequence of chromosome 7. The sequence was identical in the two sublines. A short sequence of 200bp derived from chromosome 2 was incorporated, suggesting translocation between chromosomes 2 and 7. The copy number of the short sequence was comparable to that of the neighboring sequence, suggesting coamplification. The timing of the occurrence of the putative translocation and the initiation of BFB-cycle-driven amplification during the stepwise selection were determined by using the unique junction sequences specific to these events as indicators. The results demonstrated that the translocation occurred at the step of 100 nmol/L treatment and the BFB cycle initiated in the step of 400 nmol/L-treatment. It is likely that the translocation, preceding amplification by several selection steps, activated ABCB1 gene expression. The diversity in amplification profiles between the two sublines was generated by the separately operating BFB cycles, after an initial break-and-fusion that probably occurred in a single cell.

Molecular cytogenetic characterization of doxorubicin-resistant neuroblastoma cell lines: evidence that acquired multidrug resistance results from a unique large amplification of the 7q21 region

Neuroblastoma is a heterogeneous neural crest-derived embryonic childhood neoplasm that is the second most common solid tumor found in children. Despite recent advances in combined therapy, the overall survival of patients with high-stage disease has not improved in the last decades. Treatment failure is in part attributed to multidrug resistance. To address the mechanisms involved in the development of multidrug resistance, we have generated two doxorubicin-resistant neuroblastoma cell lines (IGRN-91R and LAN-1R). These cells were shown to overexpress the MDR1 gene coding for the P-glycoprotein and were resistant to other MDR1- and non-MDR1-substrate drugs. Indeed, the MDR1 inhibitor verapamil only partially restored sensitivity to drugs, confirming that P-glycoprotein-mediated drug efflux was not responsible for 100% resistance. High-resolution and array-based comparative genomic hybridization analyses revealed the presence of an amplicon in the 7q21 region as the unique genomic alteration common to both doxorubicin-resistant cell lines. In addition to the MDR1 locus, this large amplified region is likely to harbor additional genes potentially involved in the development of drug resistance. This study represents the first molecular cytogenetic and genomic approach to identifying genomic regions involved in the multidrug-resistant phenotype of neuroblastoma. These results could lead to the identification of relevant target genes for the development of new therapeutic modalities.

Chromosomal alterations cause the high rates and wide ranges of drug resistance in cancer cells

Conventional mutation-selection theories have failed to explain (i) how cancer cells become spontaneously resistant against cytotoxic drugs at rates of up to 10(-3) per cell generation, orders higher than gene mutation, even in cancer cells; (ii) why resistance far exceeds a challenging drug-a state termed multidrug resistance; (iii) why resistance is associated with chromosomal alterations and proportional to their numbers; and (iv) why resistance is totally dependent on aneuploidy. We propose here that cancer-specific aneuploidy generates drug resistance via chromosomal alterations. According to this mechanism, aneuploidy varies the numbers and structures of chromosomes automatically, because it corrupts the many teams of proteins that segregate, synthesize, and repair chromosomes. Aneuploidy is thus a steady source of chromosomal variation from which, in classical Darwinian terms, resistance-specific aneusomies are selected in the presence of chemotherapeutic drugs. Some of the thousands of unselected genes that hitchhike with resistance-specific aneusomies can thus generate multidrug resistance. To test this hypothesis, we determined the rates of chromosomal alterations in clonal cultures of human breast and colon cancer lines by dividing the fraction of nonclonal karyotypes by the number of generations of the clone. These rates were about 10(-2) per cell generation, orders higher than mutation. Chromosome numbers and structures were determined in metaphases hybridized with color-coded chromosome-specific DNA probes. Further, we tested puromycin-resistant subclones of these lines for resistance-specific aneusomies. Resistant subclones differed from parental lines in four to seven specific aneusomies, of which different subclones shared some. The degree of resistance was roughly proportional to the number of these aneusomies. Thus, aneuploidy is the primary cause of the high rates and wide ranges of drug resistance in cancer cells.

Genomic changes identified by comparative genomic hybridisation in docetaxel-resistant breast cancer cell lines

Docetaxel is one of the most effective chemotherapeutic agents in the treatment of breast cancer. Breast cancers can have an inherent or acquired resistance to docetaxel but the causes of this resistance remain unclear. In this study high-level, docetaxel-resistant human breast cancer cell lines (MCF-7 and MDA-MB-231) were created, and comparative genomic hybridisation was used to identify genomic regions associated with resistance to docetaxel. MCF-7 resistant cells showed an amplification of chromosomes 7q21.11-q22.1, 17q23-q24.3, 18, and deletion of chromosomes 6p, 10q11.2-qter and 12p. MDA-MB-231 resistant cells showed a gain of chromosomes 5p, 7q11.1-q35, 9, and loss of chromosomes 4, 8q24.1-qter, 10, 11q23.1-qter, 12q15-q24.31, 14q and 18. Whole chromosome paints confirmed these findings. Amplification of 7q21 and loss of 10q may represent a common mechanism of acquired docetaxel resistance in breast cancer cells. This study is the first description of a genomic approach specifically to identify genomic regions involved in resistance to docetaxel.

Molecular cytogenetic characterization of drug-resistant leukemia cell lines by comparative genomic hybridization and fluorescence in situ hybridization

Resistance to chemotherapeutic drugs is one of the major difficulties encountered during cancer chemotherapy. To detect genomic aberrations underlying the acquired drug resistance, we examined three cultured human myelomonocytic leukemia cell sublines each resistant to adriamycin (ADR), 1-beta-1-D-arabinofuranosylcytosine (ara-C), or vincristine (VCR), using comparative genomic hybridization (CGH), fluorescence in situ hybridization (FISH), RT-PCR, and western blot techniques. Chromosomes 7, 10 and 16 most conspicuously showed frequent aberrations among the resistant sublines as compared to the parental KY-821 cell line. In ADR-resistant cells, gains at 7q21, 16p12, 16p13.1-13.3, 16q11.1-q12.1, and losses at 7p22-pter, 7q36-qter, 10p12, 10p11.2-pter, 10q21-q25, 10q26-qter were notable. In ara-C-resistant cells, no remarkable gain or loss on chromosome 7, but losses at 10p14-pter, 10q26-qter and 16p11.2-p11.3 were observed. In VCR-resistant cells, gain at 7q21 and losses at 10p11-p13, 10p15 and 16p11.2-p13.3 were found. FISH identified amplified signals for the MDR-1 gene located at 7q21.1 in ADR- and VCR- but not ara-C-resistant cells, and for the MRP-1 gene located at 16p13.1 in ADR-resistant cells. These findings were validated at the mRNA and protein levels. Overlapping of the amplified MRP-1 gene with MDR-1 gene may play a critical part in the acquisition of resistance to ADR. Resistance to ara-C excluded MDR-1 gene involvement and highlighted other key genes such as MXR gene. Several other genes putatively involved in the development of drug resistance might lie in other aberrated chromosomal regions.