Expression of a Tumor-Associated Antigen, RCAS1, in Canine Mammary Tumors

Abstract

ABSTRACT. Receptor-binding cancer antigen expressed on SiSo cells (RCAS1), one of novel cancer cell-surface antigens, is strongly expressed in invasive cancers. RCAS1 inhibits the in vitro growth of lymphocytes such as T cells and natural killer (NK) cells, and induces apoptotic cell death. We investigated the expression of RCAS1 in canine mammary tumor cell lines and tumor cells by immunohistochemistry, and also in situ deoxyribonucleic acid (DNA) fragmentation in tumor-infiltrating lymphocytes (TILs) by the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labeling (TUNEL) method. All canine mammary tumor cell lines expressed RCAS1 at both the messenger ribonucleic acid (mRNA) and protein level. Immunohistochemically, RCAS1 was negative in 100% of normal mammary glands, but was expressed in 100% of malignant tumors examined. In most malignant mammary tumors, RCAS1 was localized in the cytoplasm with no polarity of expression. In benign mammary tumors, it was detected on the luminal surface of the tumor cell. RCAS1 expression or localization was significantly correlated with malignancy. In situ DNA fragmentation of CD3-positive TILs was observed in RCAS1-expressing tumors. RCAS1-expressing tumors, indicating a possible induction of apoptotic cell death in TILs through RCAS1 expression. These observations suggest that RCAS1 probably plays an important role in tumor progression and escape from immune surveillance in canine mammary tumors. KEY WORDS: canine mammary tumor, DNA fragmentation, immunohistochemistry, receptor-binding cancer antigen expressed on SiSo cells (RCAS1), tumor infiltrating lymphocyte (TILs).

Ki-67 and PCNA Expression in Canine Mammary Tumors and Adjacent Nonneoplastic Mammary Glands

“…Due to the heterogeneity of pathological types and clinical presentations of CMTs, histological evidence of malignancy does not necessarily imply a malignant clinical course of the disease. 30 Therefore, in veterinary medicine, the meticulous search and communication of reliable prognostic factors in a short period of time is important for the veterinary clinician.…”

The biological role of the unique molecule RCAS1: a bioactive marker that induces connective tissue remodeling and lymphocyte apoptosis

“…It is intriguing that the incubation of NIH3T3 mouse fibroblastic cells with recombinant murine EBAG9 protein resulted in the suppression of cell growth (48). In an immunohistochemical study, canine RCAS1 was not expressed in normal mammary glands but was expressed in 100% (15 out of 15 cases) of the malignant mammary tumors examined (50). In most malignant mammary tumors, RCAS1 was localized in the cytoplasm, without polarity of expression, and in situ DNA fragmentation in a cluster of differentiation (CD) 3-positive tumor-infiltrating lymphocytes (TILs) was observed near the RCAS1expressing tumors.…”

Efeito da terapia "in vitro" com célula tronco de medula óssea em tumores mamários caninos

“…Mammary tumors are among the most common tumors in the entire female dogs [8,9]. Despite intense clinical and pathological investigation, little is known about the etiology and prognosis of these tumors.…”