Biologic significance of receptor-binding cancer antigen expressed on SiSo cells (RCAS1) as a pivotal regulator of tumor growth through angiogenesis in human uterine cancer.
BACKGROUND
The expression of receptor-binding cancer antigen expressed on SiSo cells (RCAS1) is related significantly to the overall survival of patients with various cancers. RCAS1 reportedly induces apoptotic cell death in peripheral lymphocytes, which may contribute to the escape of tumor cells from immune surveillance. RCAS1 expression also has been related to tumor invasiveness and size in uterine cervical cancer. To clarify whether RCAS1 exacerbates tumor progression, the authors investigated the association between RCAS1 expression and tumor growth potential.


METHODS
The authors constructed small interfering ribonucleic acid (RNA) (siRNA) to target RCAS1. After transfection of siRNA and the RCAS1-encoding gene, growth of tumor cells was assessed in vitro and in vivo. The correlation between RCAS1 expression and angiogenesis was investigated in the transfected cells and in inoculated tumors from nude mice. In addition, the same association was investigated immunohistochemically with tissue samples from patients with uterine cervical cancer.


RESULTS
Knockdown of RCAS1 expression by siRNA significantly suppressed the in vivo growth of SiSo and HOUA tumor cells (P < .005); however, in vitro cell growth was not affected significantly. Enhanced RCAS1 expression significantly promoted in vivo growth, but not in vitro growth, of tumors derived from COS-7 cells (P = .0039). Introduction of the RCAS1-encoding gene increased expression of vascular endothelial growth factor (VEGF). In uterine cervical cancer, RCAS1 expression was associated significantly with VEGF expression (P = .0407) and with microvessel density (P = .0108).


CONCLUSIONS
RCAS1 may be a pivotal regulator of tumor growth through angiogenesis. Continued exploration of the biologic function of RCAS1 may allow the development of novel therapeutic strategies for uterine cancer.
Sonoda
Kenzo
K
Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. kenzo@med.kyushu-u.ac.jp
Miyamoto
Shingo
S
Yamazaki
Ayano
A
Kobayashi
Hiroaki
H
Nakashima
Manabu
M
Mekada
Eisuke
E
Wake
Norio
N
D000818:Animals; D000951:Antigens, Neoplasm / Q000378:metabolism*; D015153:Blotting, Western; D019556:COS Cells; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002522:Chlorocebus aethiops; D005260:Female; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008819:Mice, Nude; D009374:Neoplasms, Experimental / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D009389:Neovascularization, Pathologic / Q000378:metabolism* / Q000473:pathology; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014594:Uterine Neoplasms / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D000951:Antigens, Neoplasm; C120762:EBAG9 protein, human; D034741:RNA, Small Interfering; D042461:Vascular Endothelial Growth Factor A