Abstract
Purpose :
Cancer-Stem cells (CSCs) refer to a subpopulation of cancer cells with stemness features, as well as metastatic and tumorigenic potential. The five-year survival rate is 15% once uveal melanoma has metastasized to distant parts of the body, thus understanding the role of CSCs in metastasis is essential for controlling the disease. Many studies have looked at stemness in cutaneous melanoma, but studies in uveal melanoma are lacking. Our objective is to isolate and characterize CSCs from both cutaneous and uveal melanoma cell lines and to study their metastatic behavior.
Methods :
Primary (WM115, MEL270) and metastatic (WM266.4, OMM2.5) melanoma cell lines were used. They were labeled with CSC markers including ALDH, CD44 and ABCB1 and sorted by fluorescence-activated cell sorting. Expression levels of key stemness markers were tested by western blotting. Cell growth behavior of subpopulations of “high” stemness and “low” stemness was also investigated through cellular assays.
Results :
Fluorescence-activated cell sorting has isolated ALDH high, ALDH low, CD44 positive, CD44 negative, ABCB1 positive and ABCB1 negative subpopulations. For both cutaneous and uveal melanoma cell lines, most cells were CD44 positive but expression level ranged from high to low. A small fraction of cutaneous cells (1-3%) expressed high ALDH, while a small fraction (1.3%) of uveal melanoma cells were positive for ABCB1.
Current cellular assay showed that ALDH high and CD44 positive melanoma cells exhibited spheroid growth behavior. They also had greater clonogenic and migratory potential than the cells expressing lower level of CSC markers.
Conclusions :
Our data shows that cutaneous and uveal melanoma cell lines contain distinct subpopulations of cells that differ in terms of stemness features. Our results also indicate that high CSC marker expression levels correlate to high stemness features such as spheroid growth and clonogenic capacity. This study shows a correlation between CSC markers and growth patterns, suggesting that using stemness we may identify subpopulations with more aggressive behavior.
This is a 2020 ARVO Annual Meeting abstract.