Expression and histopathological correlation of CCR9 and CCL25 in ovarian cancer

Ovarian carcinoma is the most lethal gynecological malignancy among women and its poor prognosis is mainly due to metastasis. Chemokine receptor CCR9 is primarily expressed by a small subset of immune cells. The interactions between CCL25 and CCR9 have been implicated in leukocyte trafficking to the small bowel, a frequent metastatic site for ovarian cancer cells. We have previously shown that ovarian cancer cells express CCR9 and play an important role in cell migration, invasion and survival in the presence of its natural ligand in vitro. In this study, we have evaluated the expression of CCR9 and CCL25 in ovarian cancer cells and clinical samples. Ovarian cancer tissue microarrays from University of Alabama at Birmingham and AccuMax were stained for CCR9 and CCL25. Aperio ScanScope was used to acquire 80X digital images and expression analysis of CCR9 and CCL25. Flow cytometry and the Image stream system were used to conform the expression of CCR9 and CCL25 in ovarian cancer cells. Our results show significantly higher (p<0.001) expression of CCR9 and CCL25 in serous adenocarcinoma followed by serous papillary cystadenoma, endometrioid adenocarcinoma, mucinous adenocarcinoma, cystadenoma, mucinous boderline adenocarcinoma, clear cell carcinoma, granulosa cell tumor, dysgerminoma, transitional cell carcinoma, Brenner tumor, yolk sac tumor, adenocarcinoma and fibroma cases, compared to non-neoplastic ovarian tissue. Similar to tissue expression, CCR9 was also significantly expressed by the ovarian cancer cell lines (OVCAR-3 and SK-OV-3) in comparison to normal adult ovarian epithelial cell. We provide the first evidence that CCR9 and its natural ligand CCL25 are highly expressed by ovarian cancer tissue and their expression correlates with histological subtypes. Expression of this chemokine receptor and its ligand CCL25 within primary tumor tissue further suggests a potential role of this chemokine-receptor axis in ovarian cancer progression.