Uveal melanoma, as opposed to cutaneous melanoma, is a tumor which is predominantly located in the center of the eye. Given its potential aggressive nature with fatal consequences, it is important... Show moreUveal melanoma, as opposed to cutaneous melanoma, is a tumor which is predominantly located in the center of the eye. Given its potential aggressive nature with fatal consequences, it is important to start treatment in a timely manner. Currently, treatment consists of decreasing the size of the tumor by means of radiation therapy or surgery, but by mapping the genetic makeup of uveal melanoma, personalized treatment potentially becomes possible. In this thesis we tried to solve a piece of this genetic puzzle by focusing on genetic and cellular differences within and between different uveal melanoma. By means of an innovative new technique, digital PCR, we aimed to visualize this so-called heterogeneity. We demonstrate that we can accurately assess which genetic aberrations are present in uveal melanoma. Moreover, we show in what percentage of cells these aberrations are present. Additionally, we illustrate which cell types play an important role in uveal melanoma development. This way, we characterized a substantial amount of different uveal melanoma based on their heterogeneity profile. Lastly, we display whether and how uveal melanomas with a specific heterogeneity profile are susceptible to treatment. Show less
Lange, M.J. de; Nell, R.J.; Velden, P.A. van der 2021
Here, we discuss the presence and roles of heterogeneity in the development of uveal melanoma. Both genetic and cellular heterogeneity are considered, as their presence became undeniable due to... Show moreHere, we discuss the presence and roles of heterogeneity in the development of uveal melanoma. Both genetic and cellular heterogeneity are considered, as their presence became undeniable due to single cell approaches that have recently been used in uveal melanoma analysis. However, the presence of precursor clones and immune infiltrate in uveal melanoma have been described as being part of the tumour already decades ago. Since uveal melanoma grow in the corpus vitreous, they present a unique tumour model because every cell present in the tumour tissue is actually part of the tumour and possibly plays a role. For an effective treatment of uveal melanoma metastasis, it should be clear whether precursor clones and normal cells play an active role in progression and metastasis. We propagate analysis of bulk tissue that allows analysis of tumour heterogeneity in a clinical setting. Show less
Lange, M.J. de; Nell, R.J.; Lalai, R.N.; Versluis, M.; Jordanova, E.S.; Luyten, G.P.M.; ... ; Velden, P.A. van der 2018
Cellular senescence, an important factor in ageing phenotypes, can be induced by replicative exhaustion or by stress. We investigated the relation between maximum replicative capacity, telomere... Show moreCellular senescence, an important factor in ageing phenotypes, can be induced by replicative exhaustion or by stress. We investigated the relation between maximum replicative capacity, telomere length, stress-induced cellular senescence, and apoptosis/cell death in human primary fibroblast strains obtained from nonagenarians of the Leiden 85-plus Study. Fibroblast strains were cultured until replicative senescence and stressed with rotenone at low passage. Telomere length, senescence-associated-β-galactosidase activity, sub-G1 content, and Annexin-V/PI positivity were measured in nonstressed and stressed conditions. Fibroblast strains with a higher replicative capacity had longer telomeres (p = .054). In nonstressed conditions, replicative capacity was not associated with β-gal activity (p = .07) and negatively with sub-G1 (p = .008). In rotenone-stressed conditions, replicative capacity was negatively associated with β-gal activity (p = .034) and positively with sub-G1 (p = .07). Summarizing, fibroblast strains with a higher maximum replicative capacity have longer telomeres, are less prone to go into stress-induced cellular senescence, and more prone to die after stress. Show less
