Mikami Y, Mikami M, Nannmoku H, Kawashima H, Sasaki T, Hada R, Inoue S
Dept. of Surgery II, Hirosaki University School of Medicine, Japan.
J Exp Clin Cancer Res. 1998 Sep;17(3):355-60.
Anemia-inducing factor (AIF) was isolated from gastric cancer tissue; however, the human placenta used as the volume of AIF for further analysis did not prove sufficient. This substance was named placental anemia-inducing factor (PAIF). PAIF directly reduces the number of erythrocytes in vitro and reduces the RBC count in rabbits to 80% when i.v. administration of 27 microg/kg of body weight is given. The aim of this study is to better define PAIF and to examine whether the identifical substance expresses on either the surface or in the cytoplasm of established gastric cancer cell lines. PAIF is a glycoprotein with about 20 KD, whose 17 amino acid residues of N terminus were sequenced after Edman treatment. The N-terminus of PAIF were determined as Lqcyncpnptadcktav. This is homologous with that of CD59, which is thought as a regulator of membrane attack complex of complement system. Expression of PAF or CD59 in four established gastric cancer cell lines were examined by indirect immunofluorescence method and by Northern blot hybridization. The cells (1 x 106) were seeded into plastic plates for three days and reacted overnight at 4 degrees C in 0.5 ml of PBS with anti-PAIF polyclonal antibody or with anti CD59 rat monoclonal antibody. Both PAIF and CD59 were stained positively on the surface and/or in the cyroplasm. The total RNAs were prepared from the four kinds of cell lines and normal human lymphocytes. CD59 mRNA was probed in all cell lines by BamH1-EcoR1 fragment of PSRa CD59. The signal levels of MKN-28, MKN-45 and KATO-III were stronger than that of MKN-74, whereas the signal of normal lymphocytes was the lowest. Although there is no decisive evidence that PAIF is exactly the same substance as CD59, and although the biological functions of these two substances are conflictive, and still to be further investigated, the 17 amino acid residues of N-terminus of PAIF expressed in gastric cancer cells were homologous with those of CD59. A derivative of CD59 may exist in gastric cancer.
贫血诱导因子（AIF）是从胃癌组织中分离出来的；然而，用作进一步分析的AIF来源——人胎盘，其数量并不充足。这种物质被命名为胎盘贫血诱导因子（PAIF）。PAIF在体外能直接减少红细胞数量，当静脉注射27微克/千克体重时，可使兔子的红细胞计数降至80%。本研究的目的是更明确地界定PAIF，并检测在已建立的胃癌细胞系的表面或细胞质中是否表达这种相同的物质。PAIF是一种约20KD的糖蛋白，经埃德曼处理后对其N端的17个氨基酸残基进行了测序。PAIF的N端序列被确定为Lqcyncpnptadcktav。这与CD59的N端序列同源，CD59被认为是补体系统膜攻击复合物的调节因子。通过间接免疫荧光法和Northern印迹杂交检测了四种已建立的胃癌细胞系中PAF或CD59的表达。将细胞（1×10⁶）接种到塑料培养板中培养三天，然后在4℃下与抗PAIF多克隆抗体或抗CD59大鼠单克隆抗体在0.5毫升PBS中反应过夜。PAIF和CD59在细胞表面和/或细胞质中均呈阳性染色。从这四种细胞系和正常人淋巴细胞中提取总RNA。用PSRa CD59的BamH1 - EcoR1片段对所有细胞系中的CD59 mRNA进行检测。MKN - 28、MKN - 45和KATO - III细胞系的信号水平强于MKN - 74细胞系，而正常淋巴细胞的信号最低。尽管没有确凿证据表明PAIF与CD59完全是同一种物质，而且这两种物质的生物学功能相互矛盾，仍有待进一步研究，但在胃癌细胞中表达的PAIF的N端17个氨基酸残基与CD59的同源。在胃癌中可能存在CD59的衍生物。
