Yano H, Iemura A, Haramaki M, Ogasawara S, Takayama A, Akiba J, Kojiro M
Department of Pathology, Kurume University School of Medicine, Kurume, Japan.
Hepatology. 1999 Jun;29(6):1708-17. doi: 10.1002/hep.510290624.
Type I interferon (IFN) receptor consists of two chains (Hu-IFN-alphaR1 and Hu-IFN-alphaR2), and Hu-IFN-alphaR2 takes a soluble (Hu-IFN-alphaR2a), short (Hu-IFN-alphaR2b), or long (Hu-IFN-alphaR2c) form. We examined the expression of type I IFN receptor, the growth-suppression effect of IFN-alpha, and their relationship in 13 liver cancer cell lines. With reverse-transcription polymerase chain reaction (RT-PCR) analysis, the expressions of Hu-IFN-alphaR1, Hu-IFN-alphaR2a, and Hu-IFN-alphaR2c were confirmed in all cell lines, and that of Hu-IFN-alphaR2b in 12 cell lines. All cell lines expressed mRNAs of a transcriptional activator, interferon regulatory factor (IRF)-1, and its antagonistic repressor (IRF-2). Flow cytometry revealed weak expression of Hu-IFN-alphaR2 on the cell surface in 12 cell lines. The soluble-form protein of Hu-IFN-alphaR2 was detected at varying levels in culture supernatants of all cell lines with enzyme-linked immunosorbent assay (ELISA). Cell proliferation was suppressed in proportion to the dose of human natural IFN-alpha at 96 hours of culture, but it was not clearly related to the expression of Hu-IFN-alphaR2 protein on the cell surface. Investigations on the morphology, DNA, and cell cycle presented four growth suppression patterns as a result of IFN-alpha: 1) induction of apoptosis and blockage of cell cycle at the S phase (9 cell lines); 2) blockage at the S phase (2 cell lines); 3) induction of apoptosis and blockage at the G2/M phase (1 cell line); and 4) blockage at the G1 phase (1 cell line). There was no evidence showing that changes in the expressions of Bcl-2, Bcl-xL, Bak, and Bax lead directly to IFN-alpha-mediated apoptosis. Our findings demonstrated that IFN-alpha would express growth-suppression effects at varying degrees by inducing inhibition of cell-cycle progression with or without apoptosis, regardless of the expression level of Hu-IFN-alphaR2 protein on the cell surface.
I型干扰素（IFN）受体由两条链（Hu-IFN-alphaR1和Hu-IFN-alphaR2）组成，Hu-IFN-alphaR2有可溶性（Hu-IFN-alphaR2a）、短型（Hu-IFN-alphaR2b）或长型（Hu-IFN-alphaR2c）三种形式。我们检测了13种肝癌细胞系中I型干扰素受体的表达、IFN-α的生长抑制作用及其相互关系。通过逆转录聚合酶链反应（RT-PCR）分析，在所有细胞系中均证实了Hu-IFN-alphaR1、Hu-IFN-alphaR2a和Hu-IFN-alphaR2c的表达，在12种细胞系中证实了Hu-IFN-alphaR2b的表达。所有细胞系均表达转录激活因子干扰素调节因子（IRF）-1及其拮抗抑制因子（IRF）-2的mRNA。流式细胞术显示，12种细胞系的细胞表面Hu-IFN-alphaR2表达较弱。采用酶联免疫吸附测定（ELISA）在所有细胞系的培养上清液中检测到不同水平的Hu-IFN-alphaR2可溶性蛋白。在培养96小时时，细胞增殖受到人天然IFN-α剂量的抑制，但与细胞表面Hu-IFN-alphaR2蛋白的表达无明显相关性。对形态学、DNA和细胞周期的研究结果显示，IFN-α导致四种生长抑制模式：1）诱导凋亡并使细胞周期阻滞于S期（9种细胞系）；2）阻滞于S期（2种细胞系）；3）诱导凋亡并阻滞于G2/M期（1种细胞系）；4）阻滞于G1期（1种细胞系）。没有证据表明Bcl-2、Bcl-xL、Bak和Bax表达的变化直接导致IFN-α介导的凋亡。我们的研究结果表明，无论细胞表面Hu-IFN-alphaR2蛋白的表达水平如何，IFN-α均可通过诱导细胞周期进程的抑制，无论有无凋亡，在不同程度上发挥生长抑制作用。
