Abstract 4254: Dynamic change of differentiation in spheroids derived from mixed small cell carcinoma/adenocarcinoma of the uterine cervix

Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, LA Small cell carcinoma of the uterine cervix (SCCC) occurs mainly in young women with poor prognosis. Clear treatment algorithm remains difficult to develop for its rarity. Herein, we report a case of SCCC with adenocarcinoma component, and analyzed the mechanism of differentiation using a spheroid culture method. CTOS (cancer tissue-originated spheroid) is a primary culture system by which highly purified and viable cancer cells are cultivated. The principle of this method is maintaining cell-cell contact throughout the preparation and culture process. CTOS preserves characters of original tumors, especially their differentiation status. We generated a panel of CTOSs from 9 SCCCs. The success rate of CTOS preparation in SCCC was 100%, indicating SCCC is one of the most suitable cancers for CTOS method. We focused on SCCCs with adenocarcinoma component. These admixed tumors have been reported in other organs, such as lung, ovary, stomach, and so on. However, the mechanism underlying mixed tumor remains unclear. One of the CTOSs retained the characteristics of mixed tumor in original tumor. Immunostaining revealed that CD99 was positive in the region of small cell carcinoma region, and CK7 in that of adenocarcinoma. CTOSs were sorted by CD99 and EpCAM (a possible stem cell marker) expression levels, and transplanted into NOD-Scid mice. Xenotumors derived from both CD99lowEpCAMlow cells and CD99lowEpCAMhigh cells showed mixed cell type in H&E staining. Immunohistochemistry revealed that CD99 was positive in the region of small cell carcinoma, and CK7 in that of adenocarcinoma. On the other hand, CD99highEpCAMhigh cells-derived xenotumor consisted of only small cell carcinoma. The tumors were positive for CD99, but negative for CK7. Next, we searched for the key factor of differentiation. It has been reported that hypoxia induced adenocarcinoma in lung adenosquamous cell carcinoma. When CTOSs were incubated in hypoxia (3%O2), FACS analysis revealed that proportion of CD99low cells increased (20.6% in normoxia, 40.2% in hypoxia). Immunostaining of CTOSs showed similar results. Thus differentiation status of a mixed type SCCC showed dynamic change of differentiation in spheroids depending on culture conditions. The research can provide insight into the origin of mixed tumor of SCCC, and may be useful for developing treatment strategy. Citation Format: Satoshi Kubota. Dynamic change of differentiation in spheroids derived from mixed small cell carcinoma/adenocarcinoma of the uterine cervix. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4254.