| 1. |
- Attarha, S., et al.
(author)
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PKN I modulates TGF beta and EGF signaling in HEC-I-A endometrial cancer cell line
- 2014
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In: Oncotargets and Therapy. - : Informa UK Limited. - 1178-6930. ; 7, s. 1397-1408
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Journal article (peer-reviewed)abstract
- Background: The response of cells to TGF beta and EGF is mediated by a network of various intracellular regulators. The signaling crosstalk between different regulators is of key importance for tumorigenesis. The crosstalk may explain the modulation of cellular responses to the same regulator by another signaling molecule. As PKN1-a serine/threonine kinase implicated in tumorigenesis was identified as potential crosstalk node for TGF beta and EGF signaling, the cellular functions that may be affected by PKN1 in a crosstalk of TGF beta and EGF were explored. Methods: To investigate the contribution of PKN1 to TGF beta and EGF signaling, transiently PKN1-transfected HEC-1-A endometrial cancer cells were generated and subjected to treatment with TGF beta, EGF, and their combination. Proliferation, apoptosis, invasion, wound healing, and migration assays were performed. The impact of PKN1 on the expression and phosphorylation of intracellular proteins was monitored by immunoblotting. Results: It was demonstrated that PKN1 modulated the responses of HEC-A-1 endometrial cancer cells to TGF beta and EGF PKN1 had an inhibitory effect on the stimulation of cell migration, and PKN1 kinase activity was required for the inhibitory effect of TGF beta and EGF on cell proliferation and invasiveness. It was observed that phosphorylation of Smad2, FAK, and Erk1/2 correlated with responses of the cells to TGF beta and EGE Conclusion: PKN1 modulates TGF beta- and EGF-dependent regulation of cell proliferation, migration, and invasiveness, and therefore is a component of the network signaling downstream of IGO and EGE
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| 2. |
- Chavali, Pavithra Lakshminarasimhan, et al.
(author)
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TLX activates MMP-2, promotes self-renewal of tumor spheres in neuroblastoma and correlates with poor patient survival.
- 2014
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In: Cell Death & Disease. - : Springer Science and Business Media LLC. - 2041-4889. ; 449:5
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Journal article (peer-reviewed)abstract
- Nuclear orphan receptor TLX (Drosophila tailless homolog) is essential for the maintenance of neural stem/progenitor cell self-renewal, but its role in neuroblastoma (NB) is not well understood. Here, we show that TLX is essential for the formation of tumor spheres in three different NB cell lines, when grown in neural stem cell media. We demonstrate that the knock down of TLX in IMR-32 cells diminishes its tumor sphere-forming capacity. In tumor spheres, TLX is coexpressed with the neural progenitor markers Nestin, CD133 and Oct-4. In addition, TLX is coexpressed with the migratory neural progenitor markers CD15 and matrix metalloproteinase-2 (MMP-2) in xenografts of primary NB cells from patients. Subsequently, we show the effect of TLX on the proliferative, invasive and migratory properties of IMR-32 cells. We attribute this to the recruitment of TLX to both MMP-2 and Oct-4 gene promoters, which resulted in the respective gene activation. In support of our findings, we found that TLX expression was high in NB patient tissues when compared with normal peripheral nervous system tissues. Further, the Kaplan-Meier estimator indicated a negative correlation between TLX expression and survival in 88 NB patients. Therefore, our results point at TLX being a crucial player in progression of NB, by promoting self-renewal of NB tumor-initiating cells and altering their migratory and invasive properties.
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| 3. |
- Saini, Ravi Kanth Rao
(author)
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Neural stam cells, TLX, and Neuroblastoma
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Neuroblastoma (NB) is one of the most commonly diagnosed extracranial tumors in children below five years of age. Moreover, NB accounts for almost 12-15% of all childhood cancer related fatalities. To date, the origin of NB has been linked to the neural crest derived sympathoadrenal progenitor cells. Progression and pathogenicity of the disease has been largely correlated with the ages of children and presence of undifferentiated neuroblasts and amplification of the MYCN oncogene. However from the clinical evidence gathered so far, MYCN amplification is related to poor prognosis but it occurs only in 20% of NB cases. Henceforth, there is a need for better diagnostic and predictive markers to stratify NB patients. NB cells express a number of neural stem cell and progenitor markers such as Oct3/4, Sox2, CD133, ABCG2, and Nestin. Since self-renewal and differentiation of neural stem cells are predominantly regulated by a number of stem cell fate determinants such as Notch, Wnt, Hedgehog, PTEN, and TLX, it is speculated that deregulation of these genes may be responsible for the pathogenicity of the disease. TLX is an orphan nuclear receptor, which is predominantly expressed in the embryonic and adult forebrain, and is considered to be a crucial regulator of neurogenesis, because of its roles in neural stem cell self-renewal and maintenance. We have identified that upon hypoxia, TLX stimulates neural stem cell renewal by promoting Oct3/4 transcription in adult hippocampal progenitors. TLX is expressed at high levels in NB cell lines. In sphere forming cells generated from these cell lines, TLX was enriched and co- expressed along with the neural progenitor markers Nestin, Oct3/4, CD133, and HIF- 2α. TLX was also co-expressed with the neural progenitor markers CD15 and MMP-2 in xenografts of primary NB-tumor initiating cells (TIC) derived from patients. Thus, TLX may be involved in the tumorigenesis of NB by promoting dedifferentiation of tumor cells. NB develops through processes which may be defined as cellular “dedifferentiation”. The ability of tumors to form spheroids is one of the manifestations of dedifferentiation and transformation. To study the mechanisms of dedifferentiation, neuroblastoma cell lines will help us to identify new diagnostic markers. We generated spheroids of the NB cell line SK-N-BE2 and performed proteomics analysis to evaluate the differential expression pattern as compared with the wild-type cells. We identified 239 proteins which were affected by the dedifferentiation process. These proteins represented several regulatory processes, such as transcription, cell cycle regulation, apoptosis, cell adhesion, metabolism, intracellular transport, stress response, and angiogenesis. An extensive analysis using Cytoscape identified “DISC-1” and “DNA-PKcs”, both of which have been previously linked to dedifferentiation and cancer. The results contribute to better understanding of mechanisms involved in Neuroblastoma pathogenesis, along with identifying possible biomarkers for the disease that may be translated to the clinic.
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| 4. |
- Saini, Ravi Kanth Rao, et al.
(author)
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Proteomics of dedifferentiation of SK-N-BE2 neuroblastoma cells
- 2014
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In: Biochemical and Biophysical Research Communications. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 454:1, s. 202-209
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Journal article (peer-reviewed)abstract
- Neuroblastoma develops through processes which include cellular dedifferentiation. Ability of tumors to form spheroids is one of the manifestations of dedifferentiation and carcinogenic transformation. To study mechanisms of dedifferentiation of neuroblastoma cells, we generated spheroids and performed a proteomics study to compare the spheroids with parental SK-N-BE2 cells. We observed that dedifferentiation induced extensive changes in the proteome profiles of the cells, which affected more than 30% of detected cellular proteins. Using mass spectrometry, we identified 239 proteins affected by dedifferentiation into spheroids as compared to the parental cells. These proteins represented such regulatory processes as transcription, cell cycle regulation, apoptosis, cell adhesion, metabolism, intracellular transport, stress response, and angiogenesis. A number of potent regulators of stemness, differentiation and cancer were detected as subnetworks formed by the identified proteins. Our validation tissue microarray study of 30 neuroblastoma cases confirmed that two of the identified proteins, DISC1 and DNA-PKcs, had their expression increased in advanced malignancies. Thus, our report unveiled extensive changes of the cellular proteome upon dedifferentiation of neuroblastoma cells, indicated top subnetworks and clusters of molecular mechanisms involved in dedifferentiation, and provided candidate biomarkers for clinical studies. (C) 2014 Elsevier Inc. All rights reserved.
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