Flow Cytometric Detection of Apoptosis and p53 Protein in OVCAR-3 and SKOV-3 Ovarian Cancer Cell Lines

Yoon, Joo Hee; Choi, Woon Min; Jo, Yoon Sung; Rha, Jong Gu; Han, Ku Taek

Abstract

OBJECTIVE
Taxol (paclitaxel)-induced apoptosis was studied to understand their biological mechanism correlated with the expression of p53 in the SKOV-3 and OVCAR-3 ovarian cancer cell lines.
MATERIALS AND METHODS
The SKOV-3 and OVCAR-3 cell lines were cultured in RPMI 1640 medium without taxol (control group) and with taxol for 24 h and 48 h (experimental group). After harvest, the cells were stained with annexin V-FITC (fluorescein isothiocyanate) and anti-cytokeratin antibodies (clone CAM5.2 and clone MNF116). They were washed and stained with p53 antibody. After then the secondary antibodies, i.e., FITC- or phycoerythrin (PE)-conjugated goat anti-mouse (GAM) immunoglobulin G (GAM IgG-FITC or GAM IgG-PE) were added in the cells and they were incubated in the dark. DNA of these cells were stained sequentially with propidium iodide (PI). Standard FACScan equipped with a 488 nm single laser was used for the analysis of these cells.
RESULTS
Both of SKOV-3 and OVCAR-3 cell lines were arrested in the G2M phase after treatment of taxol, suggesting that these cells would eventually enter into the stage of cell death. Fractions of negative cytokeratin and positive annexin V and amount of sub-G0G1 fraction indicative of apototic fractions were lower in the SKOV-3 cell line compared with that in OVCAR-3 cell line, probably as a result of lower sensitivity of SKOV-3 cell line to the taxol. p53 expression were not detected in SKOV-3 cell line. On the basis of observed findings in SKOV-3 cell line and findings of high expressions of p53 regardless of taxol treatment, no increases in their expressions according to culturing time, and gradual increases in sub-G0G1 fractions and in fractions of negative cytokeratin and positive annexin V indicative of apoptosis in OVCAR-3 cell line, we concluded that the expression of p53 would not be associated with cell cycle changes and the arrest in the G2M pahse but associated with the appearance of apotosis.
CONCLUSION
Our results suggest that flow cytometric detection of the apoptotic fractions would be an effective, fast, and accurate method for the chemosensitivity test in tumor cells before the administration of anti-cancer drugs in gynecologic cancer patients.