Presence of TIC subpopulation in endometrial cancer cells. (A) Ishikawa H cells untreated (Ishikawa H, solid bar) or pre-treated with TEA (Ishikawa H, shaded bar) were seeded onto TEA-free soft agar and cell colonies were counted 21 days later. Similarly, Hec50co cells untreated (Hec50co, solid bar) or pre-incubated with TEA (Hec50co, shaded bar) were grown in TEA-free agar for 21 days. p ≤ 0.05 vs. untreated for respective cell line; N = 3. (B) Hec50co cells were separated into the sub-populations with high (ALDH1 (+)) and low (ALDH1 (-)) activity of the enzyme ALDH1 via fluorescent cell sorting. Athymic mice were injected with 100,000 ALDH1(+) or ALDH1(-) cells and inspected for tumor growth. N = 2. (C) Ishikawa H endospheres (left panel,) and Hec50co endospheres (right panel) were cultured in the presence of a cell membrane marker PKH26 (red) and counter-stained with the live cell DNA marker CYTO16 (green). Visualization and a three dimensional reconstruction of images were performed using a Zeiss LSM 510 confocal imaging system. N = 5 (Ishikawa H) and N = 8 (Hec50co).