Gene expression profiling of IGROV1 cells after in vitro treatment with ascitic fluid from human ovarian cancer bearing mice

CpG-ODN demonstrated anti-tumor activity in IGROV-1 ascites tumor-bearing mice. To evaluate if soluble molecules present in ascitic fluid, presumably released by innate immune cells via TLR9 stimulation, is directly involved with gene expression modulation a microarray experiment was performed. IGROV-1 human ovarian carcinoma cells were adapted to growth intraperitoneally (i.p.) and maintained by serial i.p. passages of ascitic cells into healthy mice as described. Mice were injected i.p. with 2.5 x 106 ascitic cells in 0.2 ml of saline and treated starting 10-11 days later, when mice showed evident and established ascites, with CpG-ODN [phosphorothioated ODN1826 (5’-TCCATGACGTTCCTGACGTT-3’), TriLink Biotechnologies (San Diego, CA, USA)]. Delivered i.p. at a dose of 20 µg/mouse for 3 consecutive days or 1 time, control mice received saline (3 mice/group). Twenty-four hours after the last treatment with saline or CpG-ODN, ascites-bearing mice were sacrificed by cervical dislocation. Ascitic fluid was collected using a heparinized syringe and the volume recorded. The fluid was transferred to a centrifuge tube maintained on ice. After centrifugation, supernatant was removed and stored at -80°C for in vitro experiments. The ovarian cancer cell line IGROV-1 was obtained from the ATCC (Rockville, MD). Cells were routinely maintained in RPMI medium 1640 (Sigma, St. Louis, MO) supplemented with 10% FCS (Sigma) and 2 mM glutamine (Cambrex, East Rutherford, NJ). Cells were maintained at 37°C in a water-saturated atmosphere of 5% CO2 in air. 1x106 IGROV-1 cells were seeded in 6-well plates and, after seeding, cells were treated with 2 ml of culture medium in the presence of ascites from saline-treated mice or CpG-ODN-treated mice (ratio medium:ascites, 1:1) for 24 hours. At the end of treatment, cells were collected and RNA extracted.