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Helen Kalirai, Luna Djirackor, Sarah E Coupland; Phenotypic plasticity in uveal melanoma spheroids. Invest. Ophthalmol. Vis. Sci. 2019;60(9):729.
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© ARVO (1962-2015); The Authors (2016-present)
There is a belief that cancer cells retain the capacity for phenotypic plasticity, which allows them to adjust to and modify differing microenvironments. This then likely influences their metastatic capabilities and resistance to therapy. In this study we examined the influence of extracellular matrix (ECM) factors on primary UM (PUM) cells grown as 3D spheroids.
ECM was obtained from primary UM (PUM) growing in 2D culture following de-cellularisation with ammonium hydroxide. Protein expression was determined by western blot. Two PUM samples were cultured in monolayer in α-MEM media until passage three. These cells were then split in two, one portion remaining in the α-MEM media and another cultured in a melanocyte differentiation media (CnT media, Caltag melanocyte differentiation media). After two weeks of culture, these cells were made into spheroids by growing them on fibronectin coated or uncoated ultra-low attachment plates for 3 days in the two different media. The spheroids were processed and analysed by immunohistochemistry (IHC) for expression of various markers.
PUM cells produced large amounts of fibronectin and type IV collagen in 2D culture. Cells subsequently cultured in the fibronectin coated plates formed tightly packed spheroids that retained their shape after collection. Spheroids cultured in uncoated plates were loose and some cells were scattered around the well. In the α-MEM media, the spheroids did not express Mel-A or HMB45 irrespective of ECM. Instead αSMA was expressed in >80% of these cells. The spheroids grown in the CnT media were more compact and tightly packed. The cells expressed melanoma markers as well as αSMA in both ECM conditions.
Components of the ECM like fibronectin enable PUM cells to form more compact proliferative spheroids. PUM cells shown phenotypic plasticity and are able to express or repress their marker expression depending on their environment.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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