Fig. 4.

The expression of the epithelial tumor marker CK18, Ep-CAM, and the stem cell marker Oct4 in parent cells, spheroids, CD24⁻ cells, and CD24⁺ cells. a Immunofluorescent images of the parent 3AO ovarian cancer cells for Oct4, CK18, and Ep-CAM. Oct4 was expressed in a few of the cells, but CK18 and Ep-CAM were expressed in most of the cells. b, c Images of immunofluorescently stained spheroids (freshly collected, 3 days in 10% FBS culture, and 7 days in 10% FBS culture) and CD24⁻ cells (freshly sorted, 3 and 7 days in 10% FBS culture, respectively) for Oct4, CK18, and Ep-CAM, respectively. Oct4 was highly expressed on both freshly collected spheroids and freshly sorted CD24⁻ cells, and most of the cells remained positive for 3 days in medium supplemented with 10% FBS, but lost the expression for 7 days in medium supplemented with 10% FBS. The expression trend of CK18 and Ep-CAM were reversed. d The expression of Oct4, CK18, and Ep-CAM on CD24⁺ cells at the time freshly sorted, 3 and 7 days in 10%FBS culture, respectively. Oct4 was expressed only in a few cells at the time freshly sorted, 3 and 7 days in 10% FBS culture. Expression of CK18 and Ep-CAM in a large number of cells was maintained all the time