Abstract 1406: A new ovarian cancer metastasis model using multicellular spheroids generated from human ovarian cancers tissues

Abstract

Abstract Objective Most research aimed at dissecting the mechanism by which epithelial ovarian cancer (EOC) metastasizes has focused on the ability of individual cells to attach and create tumor implants. However, multicellular aggregates known as spheroids are frequently found in ovarian cancer ascites and these aggregates are increasingly thought to play an important role in metastasis not only for ovarian cancer but also other solid tumors where similar phenomena have been observed. We investigated characteristics of spheroids compared to cells grown in monolayer to further characterize these spheroids. Methods IRB approval was obtained for collection of human tissue. Fresh specimens of ovarian cancer were minced, enzymatically digested, rinsed and incubated either in DMEM to generate monolayer cultures or Mammosphere media to generate spheroids. Tumorigenicity was assessed by inoculating individual spheroids or an equal number of dissociated cells into the peritoneal cavity of SCID mice. Gene expression was examined using Western blot and quantitative real-time PCR. Results We found that cells from most ovarian cancers do generate spheroids and most of the spheroids generated are able to reliably induce peritoneal implants in SCID mice. At a molecular level, the spheroids were enriched for expression of specific markers including CD133, CD44, NANOG and OCT4, associated with populations of cancer initiating cells (CICs) as well as other stem cell markers. MiR-26b, characteristic of CICs, was significantly up regulated in spheroids compared to monolayer cells. Spheroids from CD133 positive cells induced ovarian and abdominal tumors in SCID mice, however, CD44 spheroids only generated localized tumor, suggesting that CD133 is important in metastasis of ovarian cancer. Conclusion Our results indicate that populations of cells from human EOC are capable of spontaneously generating multicellular aggregates that resemble the spheroids found in ovarian cancer ascites de novo. These spheroids are enriched for expression of markers including CD133, CD44, NANOG and OCT4, suggesting that spheroid formation enhances stem cell-like markers. CD133 might also serve as a necessary marker for metastasis of ovarian cancer. The increased expression of miR-26b in spheroids compared to monolayer culture is a novel finding that needs further investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1406. doi:1538-7445.AM2012-1406