| 1. |
- Cornmark, Louise, et al.
(författare)
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PKC activation sensitizes basal-like breast cancer cell lines to Smac mimetics
- 2016
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Ingår i: Cell death discovery. - : Springer Science and Business Media LLC. - 2058-7716. ; 2, s. 16002-16002
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for novel strategies to initiate cancer cell death. One approach is the use of Smac mimetics, which antagonize inhibitor of apoptosis proteins (IAPs). Recent studies have shown that combinations of Smac mimetics such as LBW242 or LCL161 in combination with chemotherapeutic agents increase cancer cell death. Here we show that the protein kinase C (PKC) activator TPA together with the Smac mimetic LBW242 induces cell death in two basal breast cancer cell lines (MDA-MB-468 and BT-549) that are resistant to Smac mimetic as single agent. Ten other LBW242-insensitive cancer cell lines were not influenced by the TPA+LBW242 combination. The TPA+LBW242 effect was suppressed by the PKC inhibitor GF109203X, indicating dependence on PKC enzymatic activity. The PKC effect was mediated via increased synthesis and release of TNFα, which can induce death in the presence of Smac mimetics. The cell death, coinciding with caspase-3 cleavage, was suppressed by caspase inhibition and preceded by the association of RIP1 with caspase-8, as seen in complex II formation. Smac mimetics, but not TPA, induced the non-canonical NF-κB pathway in both MDA-MB-231 and MDA-MB-468 cells. Blocking the canonical NF-κB pathway suppressed TPA induction of TNFα in MDA-MB-468 cells whereas isolated downregulation of either the canonical or non-canonical pathways did not abolish the Smac mimetic induction of the NF-κB driven genes TNFα and BIRC3 in MDA-MB-231 cells although the absolute levels were suppressed. A combined downregulation of the canonical and non-canonical pathways further suppressed TNFα levels and inhibited Smac mimetic-mediated cell death. Our data suggest that in certain basal breast cancer cell lines co-treatment of TPA with a Smac mimetic induces cell death highlighting the potential of using these pathways as molecular targets for basal-like breast cancers.
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| 2. |
- Cornmark, Louise, et al.
(författare)
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Protein kinase Cα suppresses the expression of STC1 in MDA-MB-231 breast cancer cells
- 2011
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Ingår i: Tumour Biology. - : Springer Science and Business Media LLC. - 1423-0380 .- 1010-4283. ; 32:5, s. 1023-1030
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Tidskriftsartikel (refereegranskat)abstract
- Several protein kinase C (PKC) isoforms have been shown to influence different cellular processes that may contribute to the malignancy of breast cancer cells. To obtain insight into mechanisms mediating the PKC effects, global gene expression was analyzed in MDA-MB-231 breast cancer cells in which PKCα, PKCδ or PKCε had been down-regulated with siRNA. Gene set enrichment analyses revealed that hypoxia-induced genes were enriched among genes that increased in PKCα-down-regulated cells. The STC1 mRNA, encoding stanniocalcin 1, was particularly up-regulated following depletion of PKCα and was also induced by hypoxia. Both hypoxia and PKCα down-regulation also led to increased STC1 protein levels. The results demonstrate that PKCα suppresses the expression of STC1 in breast cancer cells
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| 3. |
- Cornmark, Louise
(författare)
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Roles of protein kinase C in cell death and breast cancer
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aberrant protein kinase C (PKC) activity and expression is implicated in different malignancies. To study the role of different PKC isoforms in breast cancer the expression of PCKα, δ and ε was evaluated in breast cancer tumors. In addition the effect of siRNA-mediated knockdown of the isoforms was studied in a global gene expression analysis. We found that high PKCα levels correlate with poor prognosis, high proliferation and estrogen receptor negativity. We have also seen that PKCα suppresses the expression of stanniocalcin-1 in breast cancer cells. Previous reports have shown that PKCδ is a survival factor in several breast cancer cells. Here we show that Smac, a proapoptotic protein, associates with PKCδ in many different cancer cell lines. Furthermore, the PKCδ-Smac association was dissociated upon paclitaxel treatment. Upon PKC activation with TPA the PKCδ-Smac complex was stabilized and the paclitaxel-mediated dissociation and death was suppressed. The decreased cell death could potentially be caused by a competition between PKCδ and XIAP for Smac binding. We also show that activation of PKC sensitizes some breast cancer cell lines to a Smac mimetic called LBW242, a small molecule that mimic the effect of Smac. We found that the TPA+LBW242-mediated cell death was dependent on TPA-induced TNFα production. In addition the combination of TPA+LBW242 enables complex II formation and caspase-3 cleavage, a probable cause of the concomitant cell death observed.
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| 4. |
- Holmgren, Christian, et al.
(författare)
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Molecular characterization of protein kinase C delta (PKCδ)-Smac interactions
- 2016
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Ingår i: BMC Biochemistry. - : Springer Science and Business Media LLC. - 1471-2091. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Protein kinase C o (PKCo) is known to be an important regulator of apoptosis, having mainly pro-but also anti-Apoptotic effects depending on context. In a previous study, we found that PKCo interacts with the pro-Apoptotic protein Smac. Smac facilitates apoptosis by suppressing inhibitor of apoptosis proteins (IAPs). We previously established that the PKCo-Smac complex dissociates during induction of apoptosis indicating a functional importance. Because the knowledge on the molecular determinants of the interaction is limited, we aimed at characterizing the interactions between PKCo and Smac. Results: We found that PKCo binds directly to Smac through its regulatory domain. The interaction is enhanced by the PKC activator TPA and seems to be independent of PKCo catalytic activity since the PKC kinase inhibitor GF109203X did not inhibit the interaction. In addition, we found that C1 and C2 domains from several PKC isoforms have Smac-binding capacity. Conclusions: Our data demonstrate that the Smac-PKCo interaction is direct and that it is facilitated by an open conformation of PKCo. The binding is mediated via the PKCo regulatory domain and both the C1 and C2 domains have Smac-binding capacity. With this study we thereby provide molecular information on an interaction between two apoptosis-regulating proteins.
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| 5. |
- Kalstad Lönne, Gry, et al.
(författare)
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PKCalpha expression is a marker for breast cancer aggressiveness.
- 2010
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Ingår i: Molecular cancer. - : Springer Science and Business Media LLC. - 1476-4598. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Protein kinase C (PKC) isoforms are potential targets for breast cancer therapy. This study was designed to evaluate which PKC isoforms might be optimal targets for different breast cancer subtypes.
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| 6. |
- Karlsson, Jenny, et al.
(författare)
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Four evolutionary trajectories underlie genetic intratumoral variation in childhood cancer
- 2018
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 50:7, s. 944-950
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Tidskriftsartikel (refereegranskat)abstract
- A major challenge to personalized oncology is that driver mutations vary among cancer cells inhabiting the same tumor. Whether this reflects principally disparate patterns of Darwinian evolution in different tumor regions has remained unexplored1–5. We mapped the prevalence of genetically distinct clones over 250 regions in 54 childhood cancers. This showed that primary tumors can simultaneously follow up to four evolutionary trajectories over different anatomic areas. The most common pattern consists of subclones with very few mutations confined to a single tumor region. The second most common is a stable coexistence, over vast areas, of clones characterized by changes in chromosome numbers. This is contrasted by a third, less frequent, pattern where a clone with driver mutations or structural chromosome rearrangements emerges through a clonal sweep to dominate an anatomical region. The fourth and rarest pattern is the local emergence of a myriad of clones with TP53 inactivation. Death from disease was limited to tumors exhibiting the two last, most dynamic patterns.
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| 7. |
- Masoumi, Katarzyna, et al.
(författare)
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Identification of a novel protein kinase Cδ-Smac complex that dissociates during paclitaxel-induced cell death.
- 2012
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Ingår i: FEBS Letters. - : Wiley. - 1873-3468 .- 0014-5793. ; 586:8, s. 1166-1172
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Tidskriftsartikel (refereegranskat)abstract
- Protein kinase C (PKC) δ is a regulator of apoptosis with both pro- and anti-apoptotic effects. The mechanistic basis for the discrepant effects is not completely understood. Here we show that Smac interacts with PKCδ. The interaction depends on the N-terminus of Smac and is disrupted upon treatment with paclitaxel. This is associated with release of Smac into the cytosol. Activation of PKCδ rescues the interaction during paclitaxel exposure and suppresses the paclitaxel-mediated cell death. However, under these conditions the complex is mainly found in the cytosol suggesting that cytosolic Smac can be bound by PKCδ when PKC is activated. The data unravel a previously unrecognized interaction and suggest that PKCδ by associating with Smac may prevent its apoptotic effects. STRUCTURED SUMMARY OF PROTEIN INTERACTIONS: PKC deltaphysically interacts with SMAC by anti bait coimmunoprecipitation (View Interaction: 1, 2, 3, 4) XIAPphysically interacts with SMAC by anti tag coimmunoprecipitation(View interaction).
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| 8. |
- Saba, Karim H., et al.
(författare)
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Disruption of the TP53 locus in osteosarcoma leads to TP53 promoter gene fusions and restoration of parts of the TP53 signalling pathway
- 2023
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Ingår i: Journal of Pathology. - 0022-3417. ; , s. 147-160
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Tidskriftsartikel (refereegranskat)abstract
- TP53 is the most frequently mutated gene in human cancer. This gene shows not only loss-of-function mutations but also recurrent missense mutations with gain-of-function activity. We have studied the primary bone malignancy osteosarcoma, which harbours one of the most rearranged genomes of all cancers. This is odd since it primarily affects children and adolescents who have not lived the long life thought necessary to accumulate massive numbers of mutations. In osteosarcoma, TP53 is often disrupted by structural variants. Here, we show through combined whole-genome and transcriptome analyses of 148 osteosarcomas that TP53 structural variants commonly result in loss of coding parts of the gene while simultaneously preserving and relocating the promoter region. The transferred TP53 promoter region is fused to genes previously implicated in cancer development. Paradoxically, these erroneously upregulated genes are significantly associated with the TP53 signalling pathway itself. This suggests that while the classical tumour suppressor activities of TP53 are lost, certain parts of the TP53 signalling pathway that are necessary for cancer cell survival and proliferation are retained. In line with this, our data suggest that transposition of the TP53 promoter is an early event that allows for a new normal state of genome-wide rearrangements in osteosarcoma.
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| 9. |
- Saba, Karim H, et al.
(författare)
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Genetic profiling of a chondroblastoma-like osteosarcoma/malignant phosphaturic mesenchymal tumor of bone reveals a homozygous deletion of CDKN2A, intragenic deletion of DMD, and a targetable FN1-FGFR1 gene fusion
- 2019
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Ingår i: Genes, Chromosomes and Cancer. - : Wiley. - 1045-2257 .- 1098-2264. ; 58:10, s. 731-736
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Tidskriftsartikel (refereegranskat)abstract
- Conventional osteosarcoma is the most common primary malignancy of bone. This group of neoplasms is subclassified according to specific histological features, but hitherto there has been no correlation between subtype, treatment, and prognosis. By in-depth genetic analyses of a chondroblastoma-like osteosarcoma, we detect a genetic profile that is distinct from those previously reported in benign and malignant bone tumors. The overall genomic copy number profile was less complex than that typically associated with conventional osteosarcoma, and there was no activating point mutation in any of H3F3A, H3F3B, IDH1, IDH2, BRAF, or GNAS. Instead, we found a homozygous CDKN2A deletion, a DMD microdeletion and an FN1-FGFR1 gene fusion. The latter alteration has been described in phosphaturic mesenchymal tumor. This tumor type shares some morphological features with chondroblastoma-like osteosarcoma and we cannot rule out that the present case actually represents an FN1-FGFR1 positive malignant phosphaturic mesenchymal tumor of bone without osteomalacia.
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| 10. |
- Saba, Karim H., et al.
(författare)
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Loss of NF2 defines a genetic subgroup of non-FOS-rearranged osteoblastoma
- 2020
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Ingår i: Journal of Pathology: Clinical Research. - : Wiley. - 2056-4538. ; 6:4, s. 231-237
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Tidskriftsartikel (refereegranskat)abstract
- Osteoblastoma is a locally aggressive tumour of bone. Until recently, its underlying genetic features were largely unknown. During the past two years, reports have demonstrated that acquired structural variations affect the transcription factor FOS in a high proportion of cases. These rearrangements modify the terminal exon of the gene and are believed to stabilise both the FOS transcript and the encoded protein, resulting in high expression levels. Here, we applied in-depth genetic analyses to a series of 29 osteoblastomas, including five classified as epithelioid osteoblastoma. We found recurrent homozygous deletions of the NF2 gene in three of the five epithelioid cases and in one conventional osteoblastoma. These events were mutually exclusive from FOS mutations. Structural variations were determined by deep whole genome sequencing and the number of FOS-rearranged cases was less than previously reported (10/23, 43%). One conventional osteoblastoma displayed a novel mechanism of FOS upregulation; bringing the entire FOS gene under the control of the WNT5A enhancer that is itself activated by FOS. Taken together, we show that NF2 loss characterises a subgroup of osteoblastomas, distinct from FOS-rearranged cases. Both NF2 and FOS are involved in regulating bone homeostasis, thereby providing a mechanistic link to the excessive bone growth of osteoblastoma.
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