| 1. |
- Baryawno, Ninib, et al.
(author)
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Tumor-growth-promoting cyclooxygenase-2 prostaglandin E2 pathway provides medulloblastoma therapeutic targets
- 2008
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In: Neuro-Oncology. - : Oxford University Press (OUP). - 1522-8517 .- 1523-5866. ; 10:5, s. 661-674
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Journal article (peer-reviewed)abstract
- Prostaglandin E(2) (PGE(2)) has been shown to play important roles in several aspects of tumor development and progression. PGE(2) is synthesized from arachidonic acid by cyclooxygenases (COX) and prostaglandin E synthases (PGES) and mediates its biological activity through binding to the four prostanoid receptors EP(1) through EP(4). In this study, we show for the first time that medulloblastoma (MB), the most common malignant childhood brain tumor, expresses high levels of COX-2, microsomal prostaglandin E synthase-1, and EP(1) through EP(4) and secretes PGE(2). PGE(2) and the EP(2) receptor agonist butaprost stimulated MB cell proliferation. Treatment of MB cells with COX inhibitors suppressed PGE(2) production and induced caspase-dependent apoptosis. Similarly, specific COX-2 silencing by small interfering RNA inhibited MB cell growth. EP(1) and EP(3) receptor antagonists ONO-8713 and ONO-AE3-240, but not the EP(4) antagonists ONO-AE3-208 and AH 23848, inhibited tumor cell proliferation, indicating the significance of EP(1) and EP(3) but not EP(4) for MB growth. Administration of COX inhibitors at clinically achievable nontoxic concentrations significantly inhibited growth of established human MB xenografts. Apoptosis was increased, proliferation was reduced, and angiogenesis was inhibited in MBs treated with COX inhibitors. This study suggests that PGE(2) is important for MB growth and that therapies targeting the prostanoid metabolic pathway are potentially beneficial and should be tested in clinical settings for treatment of children with MB.
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| 2. |
- Ponthan, Frida, et al.
(author)
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Celecoxib Prevents Neuroblastoma Tumor Development and Potentiates the Effect of Chemotherapeutic Drugs In vitro and In vivo
- 2007
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In: Clinical Cancer Research. - 1078-0432 .- 1557-3265. ; 13:3, s. 1036-1044
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Journal article (peer-reviewed)abstract
- Purpose: Neuroblastoma is the most common and deadly solid tumor of childhood. Cyclooxygenase-2 is expressed in clinical neuroblastoma tumors and cell lines and inhibitors of this enzyme induce apoptosis in human neuroblastoma cells in vitro and in neuroblastoma xenografts in vivo. We hypothesized that the cyclooxygenase-2- specific inhibitor celecoxib could enhance the cytotoxic effect of chemotherapeutic drugs currently used in neuroblastoma treatment. Furthermore, we investigated if prophylactic treatment with celecoxib could prevent neuroblastoma tumor development in vivo. Experimental Design: Neuroblastoma cell cytotoxicity of chemotherapeutic drugs in combination with celecoxib was examined. In vivo, athymic rats carrying established SH-SY5Y xenografts were treated with celecoxib in combination with irinotecan, doxorubicin or etoposide, or with either drug alone. For prevention studies, rats received celecoxib in the diet, 250 to 2,500 ppm, from the time of tumor cell injection. Results: Celecoxib induced a synergistic or an additive cytotoxic effect in combination with doxorubicin, etoposide, irinotecan or vincristine in vitro. In vivo, treatment with celecoxib in combination with irinotecan or doxorubicin induced a significant growth inhibition of established neuroblastoma tumors. Rats receiving celecoxib in the diet showed a distinct dose-dependent delay in tumor development compared with untreated rats. Plasma levels of celecoxib were comparable with levels obtainable in humans. Conclusions: Celecoxib potentiates the antitumor effect of chemotherapeutic drugs currently used in neuroblastoma treatment, which argues for clinical trials combining these drugs. Celecoxib could also be a potential drug for treatment of minimal residual disease.
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| 3. |
- Segerström, Lova, et al.
(author)
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Effects of radiation on growth of two human tumour cell lines surviving a previous high dose, low dose-rate, radionuclide exposure
- 2008
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In: International Journal of Oncology. - : Spandidos Publications. - 1019-6439 .- 1791-2423. ; 33:2, s. 341-9
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Journal article (peer-reviewed)abstract
- Effects of radiation on growth of two human tumour cell lines that survived a previous high dose, low dose-rate radionuclide exposure simulating intensive radionuclide therapy, were analyzed. The purpose was to investigate whether the survivors gained therapy induced changes in growth and radiation response. The U118MG, ParRes (parental resistant), and U373MG, ParSen (parental sensitive), glioma cells were used because they are known to be low dose-rate radiation resistant and sensitive, respectively. These cells were initially exposed to high dose, low dose-rate radiation for 24 h and surviving U118MG and U373MG cells formed new cultures called SurRes (surviving resistant) and SurSen (surviving sensitive), respectively. All four cell types were then exposed to graded acute radiation doses, 0-8 Gy, and analyzed for radiation induced growth disturbances. They were also analyzed regarding DNA-content and cell cycle distributions. The SurRes cells regained in most cases the same growth rate, had the same growth delays and showed generally a similar response as the original ParRes cells to the 0-8 Gy exposures. In contrast, the SurSen cells had in all cases slower growth rate and longer growth delays than the original ParSen cells after the 0-8 Gy exposures. There were no signs of radiation-induced radioresistance. The slow growing SurSen cells contained about 80% more DNA and had more cells in G1 and fewer in G2 than the ParSen cells. The conclusion is that tumour cells surviving high dose, low dose-rate, radionuclide therapy, afterwards can react differently to a new radiation exposure.
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| 4. |
- Segerström, Lova Perup
(author)
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Novel experimental targeted therapy of neuroblastoma
- 2009
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Doctoral thesis (other academic/artistic)abstract
- Neuroblastoma, a malignancy of the sympathetic nervous system, is the most common solid extracranial tumor of infancy and is responsible for around 15% of the cancer-related deaths in children. For the entire group the survival has increased over the last decades, but despite today's intense muti-modal therapy the survival of high-risk neuroblastomas lies just around 50%. Therefore, novel treatment options are urgently needed and awaited. The development of novel cancer therapies has geared up with more and more agents entering trials and become clinically available, but this has predominately been directed towards the adult oncology area. Hopefully, legal directives will act as a 'carrot and a stick' on companies to take more interest in the pediatric area. There are concerns, with all rights, about how much efficacy a novel drug should need to show before it can be justified to move into the clinic. Preclinical animal models of cancer have established their role in the evaluation of these agents. But there is everlasting uncertainty about how truly they represent all or parts of a particular disease, and if in vivo efficacy is predictive of clinical value. This thesis describes the investigation of six novel targeted therapies, evaluated in vitro and in vivo in neuroblastoma. Anti-angiogenic antibody-therapy with bevacizumab (Avastin®) showed efficacy in vivo in three neuroblastoma xenograft models. Primary material from neuroblastoma was shown to express activated Akt and mTOR. Inhibition of the mTOR signalling pathway with rapamycin (Rapamune®) or its novel analogue CCI-779 (Torisel®) showed promising potential in vitro and in vivo, where the most interesting finding was that MYCN-amplified or over expressing cells were more sensitive. Upon treatment in vitro and in vivo we observed a down regulation of MYCN and cyclin D1 protein. Inhibition of the upstream signalling pathway with the PDK1 inhibitor OSU03012 or the dual PI3K/mTOR inhibitor PI103 did also show promising effects in vitro and in vivo. The major finding was that inhibition upstream of mTOR seemed most effective in MYCN-amplified or over expressing cells. As observed previously, treatment was associated with a down regulation of MYCN and cyclin D1 proteins. Targeting the MYCN protein with the Myc-Max disruptor 10058-F4 had effect in vitro. There were modest effects of 10058-F4 in vivo on a MYCN-amplified xenograft model, whereas in vivo in the transgenic MYCN-driven model of neuroblastoma, 10058-F4 showed some interesting potential. In summary, this thesis suggests that targeting angiogenesis in neuroblastoma appear as an interesting strategy. Primary neuroblastoma seems to be over expressing key proteins in the PI3K/Akt/mTOR pathway and targeting these with inhibitors seems to have efficacy, especially in the context of a MYCN-amplification or over expression. Also, interfering with the MYCN protein appears as an interesting approach. Some of these compounds are currently easing their way into the pediatric oncology area and hopefully in the future they, and the results generated in this thesis, will aid in improving the survival of children with neuroblastoma.
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| 5. |
- Segerström, Lova, et al.
(author)
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The Anti-VEGF Antibody Bevacizumab Potently Reduces the Growth Rate of High-Risk Neuroblastoma Xenografts
- 2006
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In: Pediatric Research. - : Springer Science and Business Media LLC. - 0031-3998 .- 1530-0447. ; 60:5, s. 576-581
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Journal article (peer-reviewed)abstract
- Neuroblastoma (NB) is a rapidly growing, well-vascularized childhood cancer that often presents with metastases. The overall five-year survival in NB is approximately 45% despite multimodality treatment, and therefore there is a clinical need for new therapeutic strategies. NB frequently overexpresses the angiogenic factor VEGF (vascular endothelial growth factor). The aim of this study was to investigate the effect of bevacizumab (Avastin, Genentech/Roche), a humanized anti-VEGF-A antibody, on NB growth in three different xenograft models, chosen to resemble high-risk NB. The human NB cell lines SK-N-AS, IMR-32 and SH-SY5Y, which are poorly differentiated and overexpress VEGF-A, were injected s.c. in immunodeficient mice. Bevacizumab was given intraperitoneally twice weekly at 5 mg/kg body weight, starting at a tumor volume of 0.3 mL. Bevacizumab significantly (p < 0.01-0.05) reduced NB growth in vivo without toxicity by causing a 30-63% reduction of angiogenesis, but had no effect on NB cell survival in vitro. Serum concentrations of VEGF-A increased two- to six-fold during bevacizumab therapy which did not result in faster tumor growth compared with control animals. Based on our experimental data we suggest consideration of bevacizumab in treatment of high-risk NB that does not respond to conventional therapy and that overexpresses VEGF.
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| 6. |
- Wickström, Malin, et al.
(author)
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The novel melphalan prodrug J1 inhibits neuroblastoma growth in vitro and in vivo
- 2007
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In: Molecular Cancer Therapeutics. - 1535-7163 .- 1538-8514. ; 6:9, s. 2409-2417
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Journal article (peer-reviewed)abstract
- Neuroblastoma is the most common extracranial solid tumor of childhood. The activity of J1 (l-melphalanyl-p-l-fluorophenylalanine ethyl ester), an enzymatically activated melphalan prodrug, was evaluated in neuroblastoma models in vitro and in vivo. Seven neuroblastoma cell lines with various levels of drug resistance were screened for cytotoxicity of J1 alone or in combination with standard cytotoxic drugs, using a fluorometric cytotoxicity assay. J1 displayed high cytotoxic activity in vitro against all neuroblastoma cell lines, with IC50 values in the submicromolar range, significantly more potent than melphalan. The cytotoxicity of J1, but not melphalan, could be significantly inhibited by the aminopeptidase inhibitor bestatin. J1 induced caspase-3 cleavage and apoptotic morphology, had additive effects in combination with doxorubicin, cyclophosphamide, carboplatin, and vincristine, and synergistically killed otherwise drug-resistant cells when combined with etoposide. Athymic rats and mice carrying neuroblastoma xenografts [SH-SY5Y, SK-N-BE(2)] were treated with equimolar doses of melphalan, J1, or no drug, and effects on tumor growth and tissue morphology were analyzed. Tumor growth in vivo was significantly inhibited by J1 compared with untreated controls. Compared with melphalan, J1 more effectively inhibited the growth of mice with SH-SY5Y xenografts, was associated with higher caspase-3 activation, fewer proliferating tumor cells, and significantly decreased mean vascular density. In conclusion, the melphalan prodrug J1 is highly active in models of neuroblastoma in vitro and in vivo, encouraging further clinical development in this patient group.
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