| 1. |
- Svensson, Karin, et al.
(författare)
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A protein kinase Cbeta inhibitor attenuates multidrug resistance of neuroblastoma cells.
- 2003
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Ingår i: BMC Cancer. - : Springer Science and Business Media LLC. - 1471-2407. ; 3:1, s. 10-10
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The acquisition of drug resistance is a major reason for poor outcome of neuroblastoma. Protein kinase C (PKC) has been suggested to influence drug resistance in cancer cells. The aim of this study was to elucidate whether inhibition of PKCbeta isoforms influences drug-resistance of neuroblastoma cells. METHODS: The effect of the PKCbeta inhibitor LY379196 on the growth-suppressing effects of different chemotherapeutics on neuroblastoma cells was analyzed with MTT assays. The effect of LY379196 on the accumulation of [3H]vincristine was also investigated RESULTS: The PKCbeta inhibitor LY379196 suppressed the growth of three neuroblastoma cell lines. LY379196 also augmented the growth-suppressive effect of doxorubicin, etoposide, paclitaxel, and vincristine, but not of carboplatin. The effect was most marked for vincristine and for the cell-line (SK-N-BE(2)) that was least sensitive to vincristine. No effect was observed on the non-resistant IMR-32 cells. Two other PKC inhibitors, Go6976 and GF109203X, also enhanced the vincristine effect. The PKC inhibitors caused an increased accumulation of [3H]vincristine in SK-N-BE(2) cells. CONCLUSIONS: This indicates that inhibition of PKCbeta could attenuate multidrug resistance in neuroblastoma cells by augmenting the levels of natural product anticancer drugs in resistant cells.
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| 2. |
- Achari, Chandrani, et al.
(författare)
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Expression of miR-34c induces G2/M cell cycle arrest in breast cancer cells
- 2014
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Ingår i: BMC Cancer. - : Springer Science and Business Media LLC. - 1471-2407. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Background: MicroRNA-34 is a family of three miRNAs that have been reported to function as tumor suppressor miRNAs and show decreased expression in various cancers. Here, we examine functions of miR-34c in basal-like breast cancer cells. Methods: Data from The Cancer Genome Atlas (TCGA) were used for evaluation of expression in primary breast cancers. Cellular processes affected by miR-34c were investigated by thymidine incorporation, Annexin V-assays and cell cycle analysis using breast cancer cell lines. Effects on potential targets were analyzed with qPCR and Western blot. Results: TCGA data revealed that miR-34c was expressed at lower levels in basal-like breast cancer tumors and low expression was associated with poor prognosis. Ectopic expression of miR-34c in basal-like breast cancer cell lines resulted in suppressed proliferation and increased cell death. Additionally, miR-34c influenced the cell cycle mainly by inducing an arrest in the G2/M phase. We found that expression levels of the known cell cycle-regulating miR-34 targets CCND1, CDK4 and CDK6, were downregulated upon miR-34c expression in breast cancer cell lines. In addition, the levels of CDC23, an important mediator in mitotic progression, were suppressed following miR-34c expression, and siRNAs targeting CDC23 mimicked the effect of miR-34c on G2/M arrest. However, protein levels of PRKCA, a predicted miR-34c target and a known regulator of breast cancer cell proliferation were not influenced by miR-34c. Conclusions: Together, our results support the role of miR-34c as a tumor suppressor miRNA also in breast cancer.
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| 3. |
- Stensman, Helena, et al.
(författare)
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Protein kinase Cepsilon is important for migration of neuroblastoma cells
- 2008
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Ingår i: BMC Cancer. - : Springer Science and Business Media LLC. - 1471-2407. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Background: Migration is important for the metastatic capacity and thus for the malignancy of cancer cells. There is limited knowledge on regulatory factors that promote the migration of neuroblastoma cells. This study investigates the hypothesis that protein kinase C (PKC) isoforms regulate neuroblastoma cell motility. Methods: PKC isoforms were downregulated with siRNA or modulated with activators and inhibitors. Migration was analyzed with scratch and transwell assays. Protein phosphorylation and expression levels were measured with Western blot. Results: Stimulation with 12-O-tetradecanoylphorbol-13-acetate (TPA) induced migration of SK-N-BE(2) C neuroblastoma cells. Treatment with the general protein kinase C (PKC) inhibitor GF109203X and the inhibitor of classical isoforms Go6976 inhibited migration while an inhibitor of PKC beta isoforms did not have an effect. Downregulation of PKC epsilon, but not of PKC alpha or PKC delta, with siRNA led to a suppression of both basal and TPA-stimulated migration. Experiments using PD98059 and LY294002, inhibitors of the Erk and phosphatidylinositol 3-kinase (PI3K) pathways, respectively, showed that PI3K is not necessary for TPA-induced migration. The Erk pathway might be involved in TPA-induced migration but not in migration driven by PKC epsilon. TPA induced phosphorylation of the PKC substrate myristoylated alanine-rich C kinase substrate (MARCKS) which was suppressed by the PKC inhibitors. Treatment with siRNA oligonucleotides against different PKC isoforms before stimulation with TPA did not influence the phosphorylation of MARCKS. Conclusion: PKC epsilon is important for migration of SK-N-BE(2) C neuroblastoma cells. Neither the Erk pathway nor MARCKS are critical downstream targets of PKC epsilon but they may be involved in TPA-mediated migration.
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| 4. |
- Winslow, Sofia, et al.
(författare)
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The expression pattern of matrix-producing tumor stroma is of prognostic importance in breast cancer
- 2016
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Ingår i: Bmc Cancer. - : Springer Science and Business Media LLC. - 1471-2407. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Background: There are several indications that the composition of the tumor stroma can contribute to the malignancy of a tumor. Here we utilized expression data sets to identify metagenes that may serve as surrogate marker for the extent of matrix production and vascularization of a tumor and to characterize prognostic molecular components of the stroma. Methods: TCGA data sets from six cancer forms, two breast cancer microarray sets and one mRNA data set of xenografted tumors were downloaded. Using the mean correlation as distance measure compact clusters with genes representing extracellular matrix production (ECM metagene) and vascularization (endothelial metagene) were defined. Explorative Cox modeling was used to identify prognostic stromal gene sets. Results: Clustering of stromal genes in six cancer data sets resulted in metagenes, each containing three genes, representing matrix production and vascularization. The ECM metagene was associated with poor prognosis in renal clear cell carcinoma and in lung adenocarcinoma but not in other cancers investigated. Explorative Cox modeling using gene pairs identified gene sets that in multivariate models were prognostic in breast cancer. This was validated in two microarray sets. Two notable genes are TCF4 and P4HA3 which were included in the sets associated with positive and negative prognosis, respectively. Data from laser-microdissected tumors, a xenografted tumor data set and from correlation analyses demonstrate the stroma specificity of the genes. Conclusions: It is possible to construct ECM and endothelial metagenes common for several cancer forms. The molecular composition of matrix-producing cells, rather than the extent of matrix production seem to be important for breast cancer prognosis.
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