Abstract P5-07-04: Characterization of a new canine inflammatory mammary cancer (IMC) cell line (IPC-366)

Abstract

Abstract Spontaneous canine inflammatory mammary cancer (IMC) shares epidemiologic, histopathological and clinical characteristics with the disease in humans and has been proposed as a natural model for human inflammatory breast cancer (IBC). Few cell lines are available to study IBC, such us SUM 149, SUM 190 and MDA-IBC3. The aim of this study was to characterize a new cell line from IMC (IPC-366) for the comparative study of both IMC and IBC. Tumors cells from a female dog with clinical IMC were collected. The pathological diagnosis of IMC was confirmed at the Veterinary Pathology Service of UCM- Veterinary Clinical Hospital. The cells were grown under adherent conditions in DMEM/F12 with 5% fetal bovine serum and 1% antibiotics (streptomycin and penicillin). The growth and mammospheres production capability, and cytological, ultrastructural and immunohistochemical (IHC) characteristics of IPC-366 were evaluated. Tumorigenicity and metastatic potential of IPC-366 were also assessed by inoculating the cells on the mammary fat pad of 18 female Balb/SCID mice and the development of tumor was monitored by imaging and luciferase assay. Microscopic examination of tumor revealed an epithelial morphology with marked anysocytosis. Doubling time of the tumor cells was approximately 24 h. Under non-adherent conditions, IPC-366 cells formed mammospheres in approximately 3 days. Cytological and histological examination of smears and ultrathin sections by electron microscopy revealed that IPC-366 is formed by highly malignant large round or polygonal cells characterized by marked atypia and prominent nucleoli and frequent multinucleated cells. Some cells had cytoplasmic empty spaces covered by cytoplasmic membrane resembling capillary endothelial cells, a phenomenon described as vasculogenic mimicry. IHC characterization of IPC-366 was basal-like: epithelial cells (AE1/AE3+, CK14+, vimentin+, actin-, p63-, ER-, PR-, HER-2 – (DAKO, HER2 P4 ), overexpressed COX-2 and high Ki-67 proliferation index (87.15 %). Imaging and luciferase assay revealed that at 3 weeks after inoculating the IPC-366 cells, a tumor mass was found in 50 % of mice. At 8 weeks after inoculation metastases in lung, liver and lymph nodes were found. Xenograph tumors maintained the original IHC characteristics of the female dog tumor. In summary, the cell line IPC-366 is a fast growing malignant triple negative cell line model of inflammatory mammary carcinoma that can be used for the comparative study of both IMC and IBC. Citation Format: Sara Caceres, Laura Peña, Lara C Alvarez de la Cerda, Maria J Illera, Richard Larson, Hui Gao, Bisrat G Debeb, Wendy A Woodward, James M Reuben, Juan C Illera. Characterization of a new canine inflammatory mammary cancer (IMC) cell line (IPC-366) [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-07-04.