| 1. |
- Baryawno, Ninib, et al.
(författare)
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Tumor-growth-promoting cyclooxygenase-2 prostaglandin E2 pathway provides medulloblastoma therapeutic targets
- 2008
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Ingår i: Neuro-Oncology. - : Oxford University Press (OUP). - 1522-8517 .- 1523-5866. ; 10:5, s. 661-674
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Tidskriftsartikel (refereegranskat)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. |
- Carlson, Lena-Maria, et al.
(författare)
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The microenvironment of human neuroblastoma supports the activation of tumor-associated T lymphocytes.
- 2013
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Ingår i: Oncoimmunology. - : Informa UK Limited. - 2162-4011 .- 2162-402X. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- Tumor infiltration by lymphocytes has been linked to improved clinical outcome in children with neuroblastoma (NB) but T-cell activation has never been demonstrated to occur within the NB microenvironment. Here we show that tumor-associated lymphocytes (TALs) obtained from lesions representing all genetic subsets of NB and autologous peripheral blood lymphocytes (PBLs) analyzed on the day of tumor excision differed in composition, phenotype and functional characteristics. The NB microenvironment appeared to promote the accumulation of CD3(+)CD8(+) T cells and contained a larger proportion of T cells expressing the interleukin-2 receptor α chain (CD25) and manifesting an effector memory (CCR7(-)CD45RA(-)) phenotype. Accordingly, the stimulation of PBLs with autologous tumor cells in short-term cultures increased the proportion of effector memory T cells, upregulated CD25, stimulated the expression of the TH1 cytokines interferon γ and tumor necrosis factor α, and reduced the expression of transforming growth factor β. In situ proliferation as well as a characteristic pattern of T-cell receptor aggregation at the contact sites with malignant cells was revealed by the immunohistochemical staining of TALs in primary tumors, indicating that the NB milieu is compatible with the activation of the immune system. Our results are compatible with the hypothesis that CD8(+) T cells are specifically activated within the NB microenvironment, which appears to be permissive for effector memory responses.
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| 3. |
- Haug, Bjørn Helge, et al.
(författare)
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MYCN-regulated miRNA-92 inhibits secretion of the tumor suppressor DICKKOPF-3 (DKK3) in neuroblastoma.
- 2011
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 1460-2180 .- 0143-3334. ; 32:7, s. 1005-12
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Tidskriftsartikel (refereegranskat)abstract
- The MYCN oncogene is frequently amplified in neuroblastoma. It is one of the most consistent markers of bad prognosis for this disease. Dickkopf-3 (DKK3) is a secreted protein of the DKK family of Wnt regulators. It functions as a tumor suppressor in a range of cancers, including neuroblastoma. MYCN was recently found to downregulate DKK3 mRNA. In this study, we show that MYCN knockdown in MYCN-amplified (MNA) neuroblastoma cell lines increases secretion of endogenous DKK3 to the culture media. MicroRNAs (miRNAs) are ∼20 nt long single-stranded RNA molecules that downregulate messenger RNAs by targeting the 3' untranslated region (3'UTR). Many miRNAs regulate genes involved in the pathogenesis of cancer and are extensively deregulated in different tumors. Using miRNA target prediction software, we found several MYCN-regulated miRNAs that could target the 3'UTR sequence of DKK3, including mir-92a, mir-92b and let-7e. Luciferase expression from a reporter vector containing the DKK3-3'UTR was decreased when this construct was cotransfected with mir-92a, mir-92b or let-7e in HEK293 cells. Mutation of the mir-92 seed sequence in the 3'UTR completely rescued the observed decrease in reporter expression when cotransfected with mir-92a and mir-92b. Antagomir and miRNA-mimic transfections in neuroblastoma cell lines confirmed that DKK3 secretion to the culture media is regulated by mir-92. Consistent with reports from other cancers, we found DKK3 to be expressed in the endothelium of primary neuroblastoma samples and to be absent in tumors with MYCN amplification. Our data demonstrate that MYCN-regulated miRNAs are able to modulate the expression of the tumor suppressor DKK3 in neuroblastoma.
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| 4. |
- Milosevic, Jelena, et al.
(författare)
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PPM1D Is a Therapeutic Target in Childhood Neural Tumors.
- 2021
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Ingår i: Cancers. - : MDPI AG. - 2072-6694. ; 13:23
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Tidskriftsartikel (refereegranskat)abstract
- Childhood medulloblastoma and high-risk neuroblastoma frequently present with segmental gain of chromosome 17q corresponding to aggressive tumors and poor patient prognosis. Located within the 17q-gained chromosomal segments is PPM1D at chromosome 17q23.2. PPM1D encodes a serine/threonine phosphatase, WIP1, that is a negative regulator of p53 activity as well as key proteins involved in cell cycle control, DNA repair and apoptosis. Here, we show that the level of PPM1D expression correlates with chromosome 17q gain in medulloblastoma and neuroblastoma cells, and both medulloblastoma and neuroblastoma cells are highly dependent on PPM1D expression for survival. Comparison of different inhibitors of WIP1 showed that SL-176 was the most potent compound inhibiting medulloblastoma and neuroblastoma growth and had similar or more potent effects on cell survival than the MDM2 inhibitor Nutlin-3 or the p53 activator RITA. SL-176 monotherapy significantly suppressed the growth of established medulloblastoma and neuroblastoma xenografts in nude mice. These results suggest that the development of clinically applicable compounds inhibiting the activity of WIP1 is of importance since PPM1D activating mutations, genetic gain or amplifications and/or overexpression of WIP1 are frequently detected in several different cancers.
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| 5. |
- Ponthan, Frida, et al.
(författare)
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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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Ingår i: Clinical Cancer Research. - 1078-0432 .- 1557-3265. ; 13:3, s. 1036-1044
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Wickström, Malin, et al.
(författare)
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The novel melphalan prodrug J1 inhibits neuroblastoma growth in vitro and in vivo
- 2007
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Ingår i: Molecular Cancer Therapeutics. - 1535-7163 .- 1538-8514. ; 6:9, s. 2409-2417
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Tidskriftsartikel (refereegranskat)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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| 7. |
- Wickström, Malin, et al.
(författare)
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Wnt/β-catenin pathway regulates MGMT gene expression in cancer and inhibition of Wnt signalling prevents chemoresistance.
- 2015
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) is commonly overexpressed in cancers and is implicated in the development of chemoresistance. The use of drugs inhibiting MGMT has been hindered by their haematologic toxicity and inefficiency. As a different strategy to inhibit MGMT we investigated cellular regulators of MGMT expression in multiple cancers. Here we show a significant correlation between Wnt signalling and MGMT expression in cancers with different origin and confirm the findings by bioinformatic analysis and immunofluorescence. We demonstrate Wnt-dependent MGMT gene expression and cellular co-localization between active β-catenin and MGMT. Pharmacological or genetic inhibition of Wnt activity downregulates MGMT expression and restores chemosensitivity of DNA-alkylating drugs in mouse models. These findings have potential therapeutic implications for chemoresistant cancers, especially of brain tumours where the use of temozolomide is frequently used in treatment.
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