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AIMS: Histone deacetylase (HDAC) inhibitors are novel therapeutics in the treatment of peripheral T-cell lymphoma, unspecified (PTCL) and diffuse large B-cell lymphoma (DLBCL), where, for unknown reasons, T-cell malignancies appear to be more sensitive than B-cell malignancies. The aim was to determine HDAC expression in DLBCL and PTCL which has not previously been investigated. METHODS AND RESULTS: The expression of HDAC1, HDAC2, HDAC6 and acetylated histone H4 was examined immunohistochemically in 31 DLBCL and 45 PTCL. All four markers showed high expression in both DLBCL and PTCL compared with normal lymphoid tissue. HDAC1 was more abundantly expressed in PTCL than in DLBCL (P = 0.0046), whereas acetylated H4 was more frequent in DLBCL (P < 0.0001), the latter suggesting a mechanism for T-cell lymphoma sensitivity to HDAC inhibitors. Moderate to strong HDAC6 expression was significantly correlated with favourable outcome (P = 0.016) in DLBCL patients, whereas the opposite effect was observed in PTCL patients (P < 0.0001). The other markers did not correlate with survival (P > 0.05). CONCLUSIONS: HDAC1, HDAC2, HDAC6 and acetylated H4 are overexpressed in DLBCL and PTCL relative to normal lymphoid tissue. Furthermore, HDAC6 may be an important prognostic marker associated with favourable outcome in DLBCL and a more aggressive course in PTCL Udgivelsesdato: 2009/5

Enzymatic inhibition of histone deacetylase (HDAC) activity is emerging as an innovative and effective approach for the treatment of cancer. A series of novel amide derivatives have been synthesized and evaluated for their ability to inhibit human HDACs. Multiple compounds were identified as potent HDAC inhibitors (HDACi), with IC(50) values in the low nanomolar (nM) range against enzyme activity in HeLa cell extracts and sub-microM for their in vitro anti-proliferative effect on cell lines. The introduction of an unsaturated linking group between the terminal aryl ring and the amide moiety was the key to obtain good potency. This approach yielded compounds such as (E)-N-[6-(hydroxyamino)-6-oxohexyl]-3-(7-quinolinyl)-2-propenamide (27) (HDAC IC(50) 8 nM) which showed potent in vivo activity in the P388 mouse leukemia syngeneic model (an increased lifespan (ILS) of 111% was obtained) Udgivelsesdato: 2009/3

An accidental extravasation of anthracycline-containing chemotherapy is a feared complication that may lead to necrosis and severe tissue destruction. For four decades, much effort has been done to prevent and treat this devastating condition. Savene has recently been proved to be very effective, and is the only approved treatment against anthracyline extravasation. It is thus now widely recommended. The present article represents a comprehensive review of, and historical insight to, the experimental and clinical studies of surgical and non-surgical treatments of extravasation during forty years of clinical anthracycline treatment Udgivelsesdato: 2009/5

Belinostat is a hydroxamate-type histone deactylase inhibitor (HDACi), which has recently entered phase I and II clinical trials. Microarray-based analysis of belinostat-treated cell lines showed an impact on genes associated with the G2/M phase of the cell cycle and downregulation of the aurora kinase pathway. Expression of 25 dysregulated genes was measured in eight differentially sensitive cell lines using a novel high-throughput assay that combines multiplex reverse transcriptase-PCR and fluorescence capillary electrophoresis. Sensitivity to belinostat and the magnitude of changes in overall gene modulation were significantly correlated. A belinostat-gene profile was specific for HDACi in three cell lines when compared with equipotent concentrations of four mechanistically different chemotherapeutic agents: 5-fluorouracil, cisplatin, paclitaxel, and thiotepa. Belinostat- and trichostatin A (HDACi)-induced gene responses were highly correlated with each other, but not with the limited changes in response to the other non-HDACi agents. Moreover, belinostat treatment of mice bearing human xenografts showed that the preponderance of selected genes were also modulated in vivo, more extensively in a drug-sensitive tumor than a more resistant model. We have demonstrated a gene signature that is selectively regulated by HDACi when compared with other clinical agents allowing us to distinguish HDACi responses from those related to other mechanisms Udgivelsesdato: 2009/9

Anthracycline-induced cardiomyopathy is a major problem in anti-cancer therapy. The only approved agent for alleviating this serious dose limiting side effect is ICRF-187 (dexrazoxane). The current thinking is that the ring-opened hydrolysis product of this agent, ADR-925, which is formed inside cardiomyocytes, removes iron from its complexes with anthracyclines, hereby reducing the concentration of highly toxic iron-anthracycline complexes that damage cardiomyocytes by semiquinone redox recycling and the production of free radicals. However, the 2 carbon linker ICRF-187 is also is a catalytic inhibitor of topoisomerase II, resulting in the risk of additional myelosuppression in patients receiving ICRF-187 as a cardioprotectant in combination with doxorubicin. The development of a topoisomerase II-inactive iron chelating compound thus appeared attractive. In the present paper we evaluate the topoisomerase II-inactive 3 carbon linker bisdioxopiperazine analog ICRF-161 as a cardioprotectant. We demonstrate that this compound does chelate iron and protects against doxorubicin-induced LDH release from primary rat cardiomyocytes in vitro, similarly to ICRF-187. The compound does not target topoisomerase II in vitro or in cells, it is well tolerated and shows similar exposure to ICRF-187 in rodents, and it does not induce myelosuppression when given at high doses to mice as opposed to ICRF-187. However, when tested in a model of chronic anthracycline-induced cardiomyopathy in spontaneously hypertensive rats, ICRF-161 was not capable of protecting against the cardiotoxic effects of doxorubicin. Modulation of the activity of the beta isoform of the topoisomerase II enzyme by ICRF-187 has recently been proposed as the mechanism behind its cardioprotection. This concept is thus supported by the present study in that iron chelation alone does not appear to be sufficient for protection against anthracycline-induced cardiomyopathy Udgivelsesdato: 2009/1/8

Udgivelsesdato: 2009

The human HDAC (histone deacetylase) family, a well-validated anticancer target, plays a key role in the control of gene expression through regulation of transcription. While HDACs can be subdivided into three main classes, the class I, class II and class III HDACs (sirtuins), it is presently unclear whether inhibiting multiple HDACs using pan-HDAC inhibitors, or targeting specific isoforms that show aberrant levels in tumours, will prove more effective as an anticancer strategy in the clinic. To address the above issues, we have tested a number of clinically relevant HDACis (HDAC inhibitors) against a panel of rhHDAC (recombinant human HDAC) isoforms. Eight rhHDACs were expressed using a baculoviral system, and a Fluor de Lystrade mark (Biomol International) HDAC assay was optimized for each purified isoform. The potency and selectivity of ten HDACs on class I isoforms (rhHDAC1, rhHDAC2, rhHDAC3 and rhHDAC8) and class II HDAC isoforms (rhHDAC4, rhHDAC6, rhHDAC7 and rhHDAC9) was determined. MS-275 was HDAC1-selective, MGCD0103 was H Udgivelsesdato: 2008/1/15

Histone deacetylase (HDAC) inhibition is a novel entity in medical oncology, and several HDAC inhibitors are in clinical trials. One of them is the hydroxamic acid belinostat (PXD101) that has demonstrated therapeutic efficacy for several clinical indications. Acetylation of histones is a key event after treatment with HDAC inhibitors, and could thus be used as a marker for monitoring cellular response to HDAC inhibitor treatment. Here we describe the utility of a newly described monoclonal antibody against acetylated H4 for immunohistochemistry on paraffin-embedded fine needle biopsies from nude mice carrying A2780 human ovarian cancer xenografts. Acetylated H4 was monitored in vivo by immunohistochemistry during treatment with belinostat, and compared with pharmacokinetics in plasma and tumor tissue. We found an increased level of acetylated H4 15 min after a single treatment (200 mg/kg i.v.) with maximum level reached after 1 h. H4 acetylation intensity reflected the belinostat concentration in plasma and tumor tissue. The threshold level for belinostat activity, indicated by acetylated H4, correlated with belinostat plasma concentrations above 1,000 ng/ml. In conclusion, examination of H4 acetylation in fine needle biopsies using the T25 antibody may prove useful in monitoring HDAC inhibitor efficacy in clinical trials involving humans with solid tumors Udgivelsesdato: 2008/5

PURPOSE: Histone deacetylases (HDAC) are involved in the regulation of gene transcription. Aberrant HDAC activity has been associated with tumorigenesis, and, therefore, HDACs are potential targets for the treatment of cancers, including tumors of the central nervous system (CNS). Belinostat is a novel, potent, pan-HDAC inhibitor with antiproliferative activity on a wide variety of tumor cell lines. We studied the cerebrospinal fluid (CSF) penetration of intravenous (IV) belinostat in a non-human primate model as a surrogate for blood:brain barrier penetration. DESIGN: Five adult rhesus monkeys received increasing doses of belinostat (10-60 mg/kg) as a 30-min IV infusion. Serial blood and CSF samples were collected over 48 h. Plasma and CSF concentrations of belinostat were quantified with an LC/MS/MS assay. Pharmacokinetic parameters were calculated using non-compartmental methods, and CSF penetration is expressed as the ratio of the area under the concentration-time curve (AUC) in CSF to the AUC in plasma. RESULTS: Belinostat was cleared rapidly from plasma with a half-life of 1.0 h, a mean residence time of 0.47 h, and a clearance of 425 ml/min/m(2). CSF penetration of belinostat was limited. CSF drug exposure was <1% of plasma drug exposure and <10% of free (non-protein bound) plasma drug exposure. CONCLUSION: IV belinostat is rapidly cleared from plasma and has limited penetration into the CSF Udgivelsesdato: 2008/8

Udgivelsesdato: 2008/9

Udgivelsesdato: 2008

Udgivelsesdato: 2008/5

Malignant cells display increased demands for energy production and DNA repair. Nicotinamide adenine dinucleotide (NAD) is required for both processes and is also continuously degraded by cellular enzymes. Nicotinamide phosphoribosyltransferase (Nampt) is a crucial factor in the resynthesis of NAD, and thus in cancer cell survival. Here, we establish the cytotoxic mechanism of action of the small molecule inhibitor CHS-828 to result from impaired synthesis of NAD. Initially, we detected cross-resistance in cells between CHS-828 and a known inhibitor of Nampt, FK866, a compound of a structurally different class. We then showed that nicotinamide protects against CHS-828-mediated cytotoxicity. Finally, we observed that treatment with CHS-828 depletes cellular NAD levels in sensitive cancer cells. In conclusion, these results strongly suggest that, like FK866, CHS-828 kills cancer cells by depleting NAD Udgivelsesdato: 2008/3/21

BACKGROUND: Recently, we have shown that dexrazoxane (ICRF-187) is an effective antidote against accidental extravasation of anthracyclines. Thus, it inhibits the lesions induced by subcutaneous (s.c.) daunorubicin, idarubicin, and doxorubicin in mice and has proven to be successful clinically as well. Dexrazoxane is a potent metal ion chelator as well as being a catalytic inhibitor of DNA topoisomerase II. However, the mechanism behind the protection against anthracycline extravasation is not known.MATERIALS AND METHODS: Mice were injected s.c. with daunorubicin or doxorubicin. Systemic N-acetylcysteine, alfa-tocoferol, amifostine, merbarone, aclarubicin, ADR-925, and EDTA were administered i.p. immediately hereafter or as a triple-treatment over six hours. Intralesional (i.l.) adjuvants were injected immediately after and into the same area as the anthracycline. The frequency, duration, and sizes of wounds were observed until complete healing of all wounds.RESULTS: Triple-treatment with systemic dexrazoxane was superior to single dosage and completely prevented lesions after s.c. daunorubicin and doxorubicin. Low-dose i.l. dexrazoxane was effective in protecting as well. In contrast, none of the other seven adjuvants was effective. Protection was not achieved with local cooling, however, topical ice did not impair the efficacy of dexrazoxane.CONCLUSIONS: Dexrazoxane is extremely effective and apparently quite specific in protecting against lesions after s.c. doxorubicin and daunorubicin.

Molekylærbiologi, Cellebiologi

Accidental extravasation of anthracyclines is a feared complication. Present treatment consists of local cooling and extensive surgical debridement, which often results in severe morbidity. All clinically important anthracyclines are topoisomerase II poisons that are antagonized by topoisomerase II catalytic inhibitors such as dexrazoxane. Therefore, we investigated whether dexrazoxane protects against extravasation lesions caused by anthracyclines. B6D2F1 mice received s.c. daunorubicin, doxorubicin, or idarubicin followed by systemic treatment with dexrazoxane or saline. One single systemic dose of dexrazoxane immediately after s.c. administration of doxorubicin, daunorubicin, or idarabicin reduced the tissue lesions (expressed as area under the curve of wound size times duration) by 96% (P < 0.0001), 70% (P < 0.0001), and 87% (P = 0.0004), respectively. Moreover, the treatment resulted in a statistically significant reduction in the fraction of mice with wounds as well as the duration of wounds. The induction of wounds was dosedependent, as was the degree of protection by dexrazoxane. Dexrazoxane could be administered up to 3 h after the anthracycline without loss of protection. Triple-dosage of dexrazoxane tended to be more effective than a single injection. Dexrazoxane had no effect on lesions induced by hydrogen peroxide. This is the first report of use of a topoisomerase II catalytic inhibitor such as dexrazoxane in the treatment of anthracycline extravasation injuries. These convincing preclinical data represent a novel nontoxic approach that can easily be implemented into the clinical handling of accidental extravasation of anthracyclines.

Udgivelsesdato: 2000-Apr, The transcription factor complex E2F-1/DP-1 regulates the G1-to-S-phase transition and has been associated with sensitivity to the S-phase-specific anticancer agents camptothecin and etoposide, which poison DNA topoisomerase I and II, respectively. To investigate the relationship between E2F-1 and drug sensitivity in detail, we established human osteosarcoma U-20S-TA cells expressing full-length E2F-1/ DP-1 under the control of a tetracycline-responsive promoter, designated UE1DP-1 cells. Topoisomerase I levels and activity as well as the number of camptothecin-induced DNA single- and double-strand breaks were unchanged in UEIDP-1/tc- cells with >10-fold E2F-1/DP-1 overexpression. However, UE1DP-1/tc- cells were hypersensitive to camptothecin in both a clonogenic assay and four different apoptotic assays. This indicates that camptothecin-induced toxicity in this model is due to the activation of an E2F-1/ DP-1-induced post-DNA damage pathway rather than an increase in the number of replication forks caused by the S-phase initiation. In contrast, topoisomerase IIalpha levels (but not topoisomerase IIbeta levels), together with topoisomerase IIalpha promoter activity, increased 2--3-fold in UE1DP-1/tc-cells. Furthermore, the number of etoposide-induced DNA single- and double-strand breaks increased in UE1DP-1/tc-cells together with a rise in clonogenic sensitivity to etoposide, but an equal apoptotic sensitivity to etoposide. The increase in topoisomerase IIalpha promoter activity in UE1DP-1/tc--cells was shown to be due to S-phase initiation per se because it was blocked by ectopic expression of dominant negative cyclin-dependent kinase 2. In conclusion, overexpression of E2F-1/DP-1 in U-20S-TA cells is sufficient to increase clonogenic sensitivity to both topoisomerase I- and II-targeted anticancer drugs. However, the mechanism by which this occurs appears to be qualitatively different. The UE1DP-1 cell model may be used to elucidate post-DNA damage mechanisms of

Udgivelsesdato: 1999-Jul-15, Bisdioxopiperazine drugs such as ICRF-187 are catalytic inhibitors of DNA topoisomerase II, with at least two effects on the enzyme: namely, locking it in a closed-clamp form and inhibiting its ATPase activity. This is in contrast to topoisomerase II poisons as etoposide and amsacrine (m-AMSA), which act by stabilizing enzyme-DNA-drug complexes at a stage in which the DNA gate strand is cleaved and the protein is covalently attached to DNA. Human small cell lung cancer NYH cells selected for resistance to ICRF-187 (NYH/187) showed a 25% increase in topoisomerase IIalpha level and no change in expression of the beta isoform. Sequencing of the entire topoisomerase IIalpha cDNA from NYH/187 cells demonstrated a homozygous G-->A point mutation at nucleotide 485, leading to a R162Q conversion in the Walker A consensus ATP binding site (residues 161-165 in the alpha isoform), this being the first drug-selected mutation described at this site. Western blotting after incubation with ICRF-187 showed no depletion of the alpha isoform in NYH/187 cells in contrast to wild-type (wt) cells, whereas equal depletion of the beta isoform was observed in the two sublines. Alkaline elution assay demonstrated a lack of inhibition of etoposide-induced DNA single-stranded breaks in NYH/187 cells, whereas this inhibition was readily apparent in NYH cells. Site-directed mutagenesis in human topoisomerase IIalpha introduced into a yeast Saccharomyces cerevisiae strain with a temperature-conditional yeast TOP2 mutant demonstrated that R162Q conferred resistance to the bisdioxopiperazines ICRF-187 and -193 but not to etoposide or m-AMSA. Both etoposide and m-AMSA induced more DNA cleavage with purified R162Q enzyme than with the wt. The R162Q enzyme has a 20-25% decreased catalytic capacity compared to the wt and was almost inactive at <0.25 mM ATP compared to the wt. Kinetoplast DNA decatenation by the R162Q enzyme at 1 mM ATP was not resistant to ICRF-187 compared to wt, whereas it was

Udgivelsesdato: 1998-Jul-16, The E2F transcription factors are key targets for the retinoblastoma protein, pRB. By inactivation of E2Fs, pRB prevents progression to the S phase. To test proliferative functions of E2F, we generated transgenic mice expressing human E2F-1 and/or human DP-1. When the hydroxymethyl glutaryl coenzyme A reductase promoter was used to express DP-1, overexpression occurred in a variety of tissues and did not confer phenotypic changes. In contrast, expression of E2F-1 from the same promoter was obtained only in testicles, in which E2F-1 overexpression caused atrophy and sterility through a process involving increased apoptosis in the germinal epithelium. This effect was potentiated by simultaneous overexpression of DP-1. Testicular atrophy as a result of overexpression of E2F-1 and DP-1 is independent of functional p53, since p53-nullizygous transgenic mice overexpressing E2F-1 and DP-1 also suffered testicular atrophy.

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