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- Blixt, Maria, et al.
(författare)
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MYCN induces cell-specific tumorigenic growth in RB1-proficient human retinal organoid and chicken retina models of retinoblastoma
- 2022
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Ingår i: Oncogenesis. - : Springer Science and Business Media LLC. - 2157-9024. ; 11:1, s. 34-
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Tidskriftsartikel (refereegranskat)abstract
- Retinoblastoma is a rare, intraocular paediatric cancer that originates in the neural retina and is most frequently caused by bi-allelic loss of RB1 gene function. Other oncogenic mutations, such as amplification and increased expression of the MYCN gene, have been found even with proficient RB1 function. In this study, we investigated whether MYCN over-expression can drive carcinogenesis independently of RB1 loss-of-function mutations. The aim was to elucidate the events that result in carcinogenesis and identify the cancer cell-of-origin. We used the chicken retina, a well-established model for studying retinal neurogenesis, and established human embryonic stem cell-derived retinal organoids as model systems. We over-expressed MYCN by electroporation of piggyBac genome-integrating expression vectors. We found that over-expression of MYCN induced tumorigenic growth with high frequency in RB1-proficient chicken retinas and human organoids. In both systems, the tumorigenic cells expressed markers for undifferentiated cone photoreceptor/horizontal cell progenitors. The over-expression resulted in metastatic retinoblastoma within 7–9 weeks in chicken. Cells expressing MYCN could be grown in vitro and, when orthotopically injected, formed tumours that infiltrated the sclera and optic nerve and expressed markers for cone progenitors. Investigation of the tumour cell phenotype determined that the potential for neoplastic growth was embryonic stage-dependent and featured a cell-specific resistance to apoptosis in the cone/horizontal cell lineage, but not in ganglion or amacrine cells. We conclude that MYCN over-expression is sufficient to drive tumorigenesis and that a cell-specific resistance to apoptosis in the cone/horizontal cell lineage mediates the cancer phenotype.
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| 2. |
- Konjusha, Dardan, 1992-
(författare)
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Modulation of retinal progenitors : A bird’s-eye view of retinal regeneration and disease
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The cell populations of the retina and their intricate organization provide us with one of the most important senses – vision. All retinal cell populations are derived from a common progenitor pool as a result of tight regulation of proliferation, differentiation, dedifferentiation, and programmed cell death. Dysregulation of these processes, or injury to the retina, can result in loss of vision or in certain cases even cancer – i.e. retinoblastoma. Understanding the mechanistic basis of these processes allows for modeling cancer and retinal regeneration. To this purpose, the embryonic chicken retina, and cultures thereof, were subjected to pharmacological intervention and modulation of gene expression. To validate findings in a human model, some studies were extended with the use of human cell cultures or retinal organoids derived from human embryonic stem cells. The focus was on the late events of retinal neurogenesis. In Paper I, we investigated endothelins as potential modulators of injury-induced retinal regeneration, which is performed by Müller cells in certain species. Injured Müller cells will dedifferentiate and return to the progenitor pool. We found that stimulation of the endothelin receptor induces dedifferentiation by transactivation of the epidermal growth factor receptor and subsequent activation of the MAPK-signaling pathway, in both chicken Müller cells and an immortalized cell line with Müller cell properties. Our findings show that endothelins have potential as possible regulators of the injury response and subsequent regeneration of lost neurons performed by Müller cells.In Paper II, the Nolz1 transcription factor and its regulation of retinal neurogenesis was explored. We show that Nolz1 acts as a negative regulator of the cell cycle in retinal progenitors, and hinders bipolar cell specification by Lim3 gene repression.In Paper III, we investigated the final neurogenic mitosis of the cone photoreceptor/horizontal cell progenitor (cPR/HC) lineage. MYCN-overexpression in a functional RB1 setting produced neoplastic growth in a cell-type and developmental-stage specific manner. The cPR/HC-lineage alone escaped apoptosis and continued proliferation both in human retinal organoids and embryonic chicken retina. Our findings have implications for the etiology of retinoblastoma and show that MYCN alone can induce cancerogenesis. The tumors arise as a result if intrinsic properties of the cPR/HC-lineage, which have not been observed in other retinal populations. Taken together, this thesis gives novel knowledge regarding the late events of retinal neurogenesis, cell-type specification, and the inherent properties of certain retinal progenitor lineages in the healthy and diseased retina.
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