IGROV1 gene expression analysis after in vivo locoregional treatment with CpG-ODN

Toll-like receptor 9 synthetic agonist oligodeoxynucleotides expressing CpG motifs are currently evaluated for their anti-tumor activity, mainly in association with DNA-damaging drugs. Microarray expression analyses of genes implicates in DNA repair on tumor cells from mice treated with CpG-OD, revealed a down-regulation in tumor cells. These findings provide the first time evidence that immune cells upon TLR9 engagement can sensitize cancer cells to DNA damaging chemotherapy. 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 (4 mice/group). 24 hours after the last treatment with saline or CpG-ODN, ascites-bearing mice were sacrificed by cervical dislocation. Tumor cells adhered to peritoneal wall were collected and extraction immediately frozen in liquid nitrogen until RNA extraction.