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  • 1
    Language: English
    In: Cancer Letters, 2009, Vol.277(1), pp.8-21
    Description: Histone deacetylases comprise a family of 18 genes, which are grouped into classes I–IV based on their homology to their respective yeast orthologues. Classes I, II, and IV consist of 11 family members, which are referred to as “classical” HDACs, whereas the 7 class III members are called sirtuins. Classical HDACs are a promising novel class of anti-cancer drug targets. First HDAC inhibitors have been evaluated in clinical trials and show activity against several cancer diseases. However, these compounds act unselectively against several or all 11 HDAC family members. As a consequence, clinical phase I trials document a wide range of side effects. Therefore, the current challenge in the field is to define the cancer relevant HDAC family member(s) in a given tumor type and to design selective inhibitors, which target cancer cells but leave out normal cells. Knockout of single HDAC family members in mice produces a variety of phenotypes ranging from early embryonic death to viable animals with only discrete alterations, indicating that potential side effects of HDAC inhibitors depend on the selectivity of the compounds. Recently, several studies have shown that certain HDAC family members are aberrantly expressed in several tumors and have non-redundant function in controlling hallmarks of cancer cells. The aim of this review is to discuss individual HDAC family members as drug targets in cancer taking into consideration their function under physiological conditions and their oncogenic potential in malignant disease.
    Keywords: Histone Deacetylase ; Hdac ; Hdac Inhibitor ; Cancer ; Development ; Therapy ; Medicine
    ISSN: 0304-3835
    E-ISSN: 1872-7980
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  • 2
    In: International Journal of Cancer, 01 February 2014, Vol.134(3), pp.703-716
    Description: Based on extensive pre‐clinical studies, the oncolytic parvovirus H‐1 (H‐1PV) is currently applied to patients with recurrent glioblastoma in a phase I/IIa clinical trial (ParvOryx01, NCT01301430). Cure rates of about 40% in pediatric high‐risk medulloblastoma (MB) patients also indicate the need of new therapeutic approaches. In order to prepare a future application of oncolytic parvovirotherapy to MB, the present study preclinically evaluates the cytotoxic efficacy of H‐1PV on MB cells and characterizes cellular target genes involved in this effect. Six MB cell lines were analyzed by whole genome oligonucleotide microarrays after treatment and the results were matched to known molecular and cytogenetic risk factors. In contrast to non‐transformed infant astrocytes and neurons, in five out of six MB cell lines lytic H‐1PV infection and efficient viral replication could be demonstrated. The cytotoxic effects induced by H‐1PV were observed at LD50s below 0.05 p. f. u. per cell indicating high susceptibility. Gene expression patterns in the responsive MB cell lines allowed the identification of candidate target genes mediating the cytotoxic effects of H‐1PV. H‐1PV induced down‐regulation of key regulators of early neurogenesis shown to confer poor prognosis in MB such as ZIC1, FOXG1B, MYC, and NFIA. In MB cell lines with genomic amplification of MYC, expression of MYC was the single gene most significantly repressed after H‐1PV infection. H‐1PV virotherapy may be a promising treatment approach for MB since it targets genes of functional relevance and induces cell death at very low titers of input virus. What's new? Medulloblastoma, the most frequent pediatric brain cancer, causes death in about 60 percent of high‐risk patients, and so there is a major need for novel, highly effective therapies. One therapy of interest is parvovirus H‐1 (H‐1PV), which was found in this study to produce marked cytotoxic effects in six medulloblastoma cell lines. Gene expression profiling revealed that H‐1PV infection causes down‐regulation of key regulatory genes involved in early neurogenesis, with significant repression of . The master regulators affected may represent putative direct or indirect H‐1PV target genes.
    Keywords: Medulloblastoma ; Oncolytic Virus ; Parvovirus H‐1pv ; Cellular Targets ; Myc ; Master Regulators Of Neurogenesis
    ISSN: 0020-7136
    E-ISSN: 1097-0215
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  • 3
    Language: English
    In: The Journal of clinical investigation, April 2011, Vol.121(4), pp.1344-8
    Description: Pilocytic astrocytoma (PA) is the most common type of primary brain tumor in children and the second most frequent cancer in childhood. Children with incompletely resected PA represent a clinically challenging patient cohort for whom conventional adjuvant therapies are only moderately effective. This has produced high clinical demand for testing of new molecularly targeted treatments. However, the development of new therapeutics for PA has been hampered by the lack of an adequate in vivo tumor model. Recent studies have identified activation of MAPK signaling, mainly by oncogenic BRAF activation, as a hallmark genetic event in the pathogenesis of human PA. Using in vivo retroviral somatic gene transfer into mouse neural progenitor cells, we have shown here that ectopic expression of the activated BRAF kinase domain is sufficient to induce PA in mice. Further in vitro analyses demonstrated that overexpression of activated BRAF led to increased proliferation of primary mouse astrocytes that could be inhibited by treatment with the kinase inhibitor sorafenib. Our in vivo model for PA shows that the activated BRAF kinase domain is sufficient to induce PA and highlights its role as a potential therapeutic target.
    Keywords: Astrocytoma -- Etiology ; Brain Neoplasms -- Etiology ; Proto-Oncogene Proteins B-Raf -- Genetics
    ISSN: 00219738
    E-ISSN: 1558-8238
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  • 4
    Language: English
    In: International Journal of Cancer, 01 May 2013, Vol.132(9), pp.2200-2208
    Description: Inhibition of histone deacetylase (HDAC) activity as stand‐alone or combination therapy represents a promising therapeutic approach in oncology. The pan‐ or class I HDAC inhibitors (HDACi) currently approved or in clinical studies for oncology give rise to dose‐limiting toxicities, presumably because of the inhibition of several HDACs. This could potentially be overcome by selective blockade of single HDAC family members. Here we report that HDAC11, the most recently identified zinc‐dependent HDAC, is overexpressed in several carcinomas as compared to corresponding healthy tissues. HDAC11 depletion is sufficient to cause cell death and to inhibit metabolic activity in HCT‐116 colon, PC‐3 prostate, MCF‐7 breast and SK‐OV‐3 ovarian cancer cell lines. The antitumoral effect induced can be mimicked by enforced expression of a catalytically impaired HDAC11 variant, suggesting that inhibition of the enzymatic activity of HDAC11 by small molecules could trigger the desired phenotypic changes. HDAC11 depletion in normal cells causes no changes in metabolic activity and viability, strongly suggesting that tumor‐selective effects can be achieved. Altogether, our data show that HDAC11 plays a critical role in cancer cell survival and may represent a novel drug target in oncology. What's new? Histone deacetylase (HDAC) enzymes influence the regulation of numerous cellular processes, and their inhibition by small molecules has been shown to provide benefits against multiple cancer types. Here, HDAC11, a recently identified member of the HDAC family, was found to play an important role in the control of proliferation and survival pathways in several carcinoma cell lines. The high incidence of the tumors represented suggests that HDAC11 could be a valuable drug target in oncology.
    Keywords: Chromatin Modulation ; Targeted Therapy ; Histone Deacetylase ; Colon Cancer ; Prostate Cancer
    ISSN: 0020-7136
    E-ISSN: 1097-0215
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  • 5
    Language: English
    In: International Journal of Radiation Oncology, Biology, Physics, 01 November 2011, Vol.81(3), pp.e7-e13
    Description: To investigate treatment outcome and prognostic factors after radiation therapy in patients with medulloblastomas (MB). Sixty-six patients with histologically confirmed MB were treated at the University Hospital of Heidelberg between 1985 and 2009. Forty-two patients (64%) were pediatric (≤18 years), and 24 patients (36%) were adults. Tumor resection was performed in all patients and was complete in 47%. All patients underwent postoperative craniospinal irradiation (CSI) delivering a median craniospinal dose of 35.5 Gy with additional boosts to the posterior fossa up to 54.0 Gy. Forty-seven patients received chemotherapy, including 21 in whom chemotherapy was administered before CSI. Statistical analysis was performed using the log-rank test and the Kaplan-Meier method. Median follow-up was 93 months. Overall survival (OS) and local and distant progression-free survival (LPFS and DPFS) were 73%, 62%, and 77% at 60 months. Both local and distant recurrence predisposed for significantly reduced OS. Macroscopic complete tumor resection, desmoplastic histology and early initiation of postoperative radiation therapy within 28 days were associated with improved outcome. The addition of chemotherapy did not improve survival rates. Toxicity was moderate. Complete resection of MB followed by CSI yields long survival rates in both children and adults. Delayed initiation of CSI is associated with poor outcome. Desmoplastic histology is associated with improved survival. The role of chemotherapy, especially in the adult population, must be further investigated in clinical studies.
    Keywords: Medulloblastoma ; Radiochemotherapy ; Craniospinal Irradiation ; Prognostic Factors ; Medicine
    ISSN: 0360-3016
    E-ISSN: 1879-355X
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  • 6
    Language: English
    In: International Journal of Cancer, 01 September 2010, Vol.127(5), pp.1230-1239
    Description: Despite multimodal therapeutic concepts, advanced localized and high‐risk neuroblastoma remains a therapeutic challenge with a long‐term survival rate below 50%. Consequently, new modalities for the treatment of neuroblastoma, ., oncolytic virotherapy are urgently required. H‐1PV is a rodent parvovirus devoid of relevant pathogenic effects in infected adult animals. In contrast, the virus has oncolytic properties and is particularly cytotoxic for transformed or tumor‐derived cells of various species including cells of human origin. Here, a preclinical assessment of the application of oncolytic H‐1PV for the treatment of neuroblastoma cells was performed. Infection efficiency, viral replication and lytic activity of H‐1PV were analyzed in 11 neuroblastoma cell lines with different MYCN status. Oncoselectivity of the virus was confirmed by the infection of short term cultures of nonmalignant infant cells of different origin. In these nontransformed cells, no effect of H‐1PV on viability or morphology of the cells was observed. In contrast, a lytic infection was induced in all neuroblastoma cell lines examined at MOIs between 0.001 and 10 pfu/cell. H‐1PV actively replicated with virus titres increasing up to 5,000‐fold within 48–96 hr after infection. The lytic effect of H‐1PV was observed independent of MYCN oncogene amplification or differentiation status. Moreover, a significant G2‐arrest and induction of apoptosis could be demonstrated. Infection efficiency, rapid virus replication and exhaustive lytic effects on neuroblastoma cells together with the low toxicity of H‐1PV for nontransformed cells, render this parvovirus a promising candidate for oncolytic virotherapy of neuroblastoma.
    Keywords: Neuroblastoma ; Oncolytic Virus ; Parvovirus H‐1pv ; Apoptosis
    ISSN: 0020-7136
    E-ISSN: 1097-0215
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  • 7
    Language: English
    In: Clinical cancer research : an official journal of the American Association for Cancer Research, 15 June 2010, Vol.16(12), pp.3240-52
    Description: Medulloblastomas are the most common malignant brain tumors in childhood. Survivors suffer from high morbidity because of therapy-related side effects. Thus, therapies targeting tumors in a specific manner with small molecules such as histone deacetylase (HDAC) inhibitors are urgently warranted. This study investigated the expression levels of individual human HDAC family members in primary medulloblastoma samples, their potential as risk stratification markers, and their roles in tumor cell growth. Gene expression arrays were used to screen for HDAC1 through HDAC11. Using quantitative real time reverse transcriptase-PCR and immunohistochemistry, we studied the expression of HDAC5 and HDAC9 in primary medulloblastoma samples. In addition, we conducted functional studies using siRNA-mediated knockdown of HDAC5 and HDAC9 in medulloblastoma cells. HDAC5 and HDAC9 showed the highest expression in prognostically poor subgroups. This finding was validated in an independent set of medulloblastoma samples. High HDAC5 and HDAC9 expression was significantly associated with poor overall survival, with high HDAC5 and HDAC9 expression posing an independent risk factor. Immunohistochemistry revealed a strong expression of HDAC5 and HDAC9 proteins in most of all primary medulloblastomas investigated. siRNA-mediated knockdown of HDAC5 or HDAC9 in medulloblastoma cells resulted in decreased cell growth and cell viability. HDAC5 and HDAC9 are significantly upregulated in high-risk medulloblastoma in comparison with low-risk medulloblastoma, and their expression is associated with poor survival. Thus, HDAC5 and HDAC9 may be valuable markers for risk stratification. Because our functional studies point toward a role in medulloblastoma cell growth, HDAC5 and HDAC9 may potentially be novel drug targets.
    Keywords: Biomarkers, Tumor -- Metabolism ; Brain Neoplasms -- Metabolism ; Histone Deacetylases -- Metabolism ; Medulloblastoma -- Metabolism ; Repressor Proteins -- Metabolism
    ISSN: 1078-0432
    E-ISSN: 15573265
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  • 8
    Language: English
    In: International Journal of Radiation Oncology, Biology, Physics, 2010, Vol.78(1), pp.237-245
    Description: Histone deacetylase inhibitors (HDACIs) can enhance the sensitivity of cells to photon radiation treatment (XRT) by altering numerous molecular pathways. We investigated the effect of pan-HDACIs such as suberoylanilide hydroxamic acid (SAHA) on radiation response in two osteosarcoma (OS) and two rhabdomyosarcoma (RMS) cell lines. Clonogenic survival, cell cycle analysis, and apoptosis were examined in OS (KHOS-24OS, SAOS2) and RMS (A-204, RD) cell lines treated with HDACI and HDACI plus XRT, respectively. Protein expression was investigated via immunoblot analysis, and cell cycle analysis and measurement of apoptosis were performed using flow cytometry. SAHA induced an inhibition of cell proliferation and clonogenic survival in OS and RMS cell lines and led to a significant radiosensitization of all tumor cell lines. Other HDACI such as M344 and valproate showed similar effects as investigated in one OS cell line. Furthermore, SAHA significantly increased radiation-induced apoptosis in the OS cell lines, whereas in the RMS cell lines radiation-induced apoptosis was insignificant with and without SAHA. In all investigated sarcoma cell lines, SAHA attenuated radiation-induced DNA repair protein expression (Rad51, Ku80). Our results show that HDACIs enhance radiation action in OS and RMS cell lines. Inhibition of DNA repair, as well as increased apoptosis induction after exposure to HDACIs, can be mechanisms of radiosensitization by HDACIs.
    Keywords: Sarcoma ; Histone Deacetylase Inhibition ; Suberoylanilide Hydroxamic Acid (Saha) ; Radiosensitization ; Medicine
    ISSN: 0360-3016
    E-ISSN: 1879-355X
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  • 9
    Language: English
    In: The Lancet, 12 January 2013, Vol.381(9861), pp.125-132
    Description: Tuberous sclerosis complex is a genetic disorder leading to constitutive activation of mammalian target of rapamycin (mTOR) and growth of benign tumours in several organs. In the brain, growth of subependymal giant cell astrocytomas can cause life-threatening symptoms—eg, hydrocephalus, requiring surgery. In an open-label, phase 1/2 study, the mTOR inhibitor everolimus substantially and significantly reduced the volume of subependymal giant cell astrocytomas. We assessed the efficacy and safety of everolimus in patients with subependymal giant cell astrocytomas associated with tuberous sclerosis complex. In this double-blind, placebo-controlled, phase 3 trial, patients (aged 0–65 years) in 24 centres in Australia, Belgium, Canada, Germany, the UK, Italy, the Netherlands, Poland, Russian Federation, and the USA were randomly assigned, with an interactive internet-response system, in a 2:1 ratio to oral everolimus 4·5 mg/m per day (titrated to achieve blood trough concentrations of 5–15 ng/mL) or placebo. Eligible patients had a definite diagnosis of tuberous sclerosis complex and at least one lesion with a diameter of 1 cm or greater, and either serial growth of a subependymal giant cell astrocytoma, a new lesion of 1 cm or greater, or new or worsening hydrocephalus. The primary endpoint was the proportion of patients with confirmed response—ie, reduction in target volume of 50% or greater relative to baseline in subependymal giant cell astrocytomas. Analysis was by intention to treat. This study is registered with , number . 117 patients were randomly assigned to everolimus (n=78) or placebo (n=39). 27 (35%) patients in the everolimus group had at least 50% reduction in the volume of subependymal giant cell astrocytomas versus none in the placebo group (difference 35%, 95% CI 15–52; one-sided exact Cochran-Mantel-Haenszel test, p〈0·0001). Adverse events were mostly grade 1 or 2; no patients discontinued treatment because of adverse events. The most common adverse events were mouth ulceration (25 [32%] in the everolimus group two [5%] in the placebo group), stomatitis (24 [31%] eight [21%]), convulsion (18 [23%] ten [26%]), and pyrexia (17 [22%] six [15%]). These results support the use of everolimus for subependymal giant cell astrocytomas associated with tuberous sclerosis. Additionally, everolimus might represent a disease-modifying treatment for other aspects of tuberous sclerosis. Novartis Pharmaceuticals.
    Keywords: Medicine
    ISSN: 0140-6736
    E-ISSN: 1474-547X
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  • 10
    Language: English
    In: BMC Cancer, 01 August 2010, Vol.10(1), p.450
    Description: Abstract Background Desmoplasia in medulloblastoma is often diagnosed in adult patients and was repeatedly associated with improved results. Today, all medulloblastoma patients receive intensive multimodal treatment including surgery, radiotherapy and chemotherapy. This study was set up to investigate treatment outcome and prognostic factors after radiation therapy in patients with desmoplastic medulloblastomas. Methods Twenty patients treated for desmoplastic medulloblastoma in the Department of Radiation Oncology at the University of Heidelberg between 1984 and 2007 were included. Data were collected retrospectively. Tumor resection was performed in all patients. All patients underwent postsurgical radiotherapy (RT). Two patients underwent whole brain radiotherapy (WBRT), and 18 patients received craniospinal irradiation (CSI). In all patients, an additional boost was delivered to the posterior fossa. The median dose to the whole brain and the craniospinal axis was 35.2 Gray (Gy), and 54.4 Gy to the posterior fossa. Fourteen patients received chemotherapy, including seven who were treated with combined radiochemotherapy and twelve who received adjuvant chemotherapy. Statistical analysis was performed using the log-rank test and the Kaplan-Meier method. Results Median follow-up was 59 months. Overall (OS), local (LPFS) and distant progression-free survival (DPFS) was 80%, 71.2%, and 83.3% at 60 months. Patients who suffered from local or distant relapses had significantly worse outcome. Five patients died from recurrent medulloblastoma. Treatment-associated toxicity was acceptable. Conclusions Multimodal approaches with surgical resection followed by chemoirradiation achieved high response rates with long OS in desmoplastic medulloblastoma patients. Staging parameters expected to predict for poor prognosis did not significantly influence outcome. However, success of any first line regimen had strong impact on disease control, and remission was achieved in no patient with relapsing disease. Multimodal concepts must be evaluated in further clinical trials.
    Keywords: Medicine
    ISSN: 1471-2407
    E-ISSN: 1471-2407
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