ANTIPROLIFERATIVE OF INTERFERON ON BREAST CANCER CELLS

除了它们的抗病毒活性外，IFN还抑制这两种病毒的生长 正常细胞和转化细胞。干扰素的作用机制 对生长抑制的认识还不完全清楚。IFN可以通过以下方式行事 干扰生长因子的增殖刺激。这个 这项建议的主要目标是通过以下方式理解 哪种干扰素可抑制表皮生长因子 (EGF)刺激人乳腺肿瘤细胞系S4的生长。 我们实验室以前的数据表明，干扰素可能会抑制S4 生长部分是通过阻断EGF的有丝分裂信号实现的。至 更全面地描述干扰素在该系统中的作用机制， 我们建议进行以下研究： 具体目标包括： 1.进一步研究干扰素对EGF的生物学作用-- 刺激S4细胞生长：我们将评估干扰素对S4细胞生长的影响 对数生长对照和EGF刺激的S4细胞。我们 然后将确定干扰素对EGF诱导的刺激的影响 静止的S4细胞的DNA合成。我们将评估 干扰素的生长抑制作用与时间的依赖关系 暴露于干扰素。动力学研究将有助于确定抑制作用是否 是细胞周期特有的。我们将确定干扰素是否诱导了 抑制EGF的反应具有剂量依赖性，其特征是 竞争性或非竞争性的相互作用。我们还将 测定微管解离剂的能力 克服干扰素对EGF刺激DNA的影响 综合。 2.检测干扰素对表皮生长因子受体(EGFR)的影响 生理学：干扰素诱导的细胞亲和力和数量的变化 EGFR、受体内化、EGFR mRNA转录 受体结构和磷酸化将被探究。干扰素 诱导早期细胞内信号通路的变化，如 检测胞浆内游离钙离子的变化。 3.检测干扰素对EGF诱导表达的影响 关于光癌基因c-myc：我们将探索稳定的变化 表皮生长因子对对照组和干扰素处理细胞c-myc表达的影响 刺激。我们将确定c-myc转录的变化 是由于两种转录率(通过核流失)的变化 转录实验)或c-myc mRNA的稳定性。 IFN现在被认为是自然出现的负增长 在限制细胞增殖中可能起重要作用的调节因子 在活体内。干扰素可以拮抗生长因子介导的血管紧张素转换酶 细胞增殖。建议的研究将澄清机制。 干扰素诱导的对人类肿瘤细胞系的生长抑制。

In addition to their antiviral activity, IFNs inhibit growth of both normal and transformed cells. The mechanisms of IFN-mediated growth inhibition are not fully understood. IFNs may act by interfering with proliferative stimulus of growth factors. The primary objective of this proposal is to understood the means by which interferon (IFN) inhibits the epidermal-growth factor (EGF)-stimulated growth of a human breast tumor cell line, S4. Previous data from our laboratory indicate IFN may inhibit S4 growth in part by interrupting the mitogenic signal of EGF. To more fully characterize IFN mechanisms of action in this system, we propose the following studies: Specific aims include the following: 1. To further characterize the biological action of IFN on EGF- stimulated growth of S4 cells: We will assess the effect of IFN on logarithmically growing control and EGF-stimulated S4 cells. We will then determine the effect of IFN on EGF-induced stimulation of DNA synthesis by quiescent S4 cells. We will assess the dependence of the growth inhibitory effect of IFN on time of exposure to IFN. Kinetic studies will help determine if inhibition is cell-cycle specific. We will determine if the IFN induced inhibition of EGF response is dose-dependent and characteristic of competitive or noncompetitive interactions. We will also determine the ability of microtubule dissociating agents to overcome IFN's effect on EGF induced stimulation of DNA synthesis. 2. To determine IFN induced changes in EGF receptor (EGFR) physiology: IFN induced changes in the affinity and number of EGFR, receptor internalization, transcription of EGFR mRNA, receptor structure, and phosphorylation will be explored. IFN induced changes in early intracellular signaling pathways such as changes in cytoplasmic free Ca2+ will be examined. 3. To characterize the effect of IFN on EGF induced expression of the photooncogene c-myc: We will explore changes in steady state levels of c-myc in control and IFN treated cells after EGF stimulation. We will determine if changes in c-myc transcription is due to changes in either transcription rates (by nuclear run off transcription assays) or the stability of c-myc mRNA. IFNs are now regarded as naturally occurring negative growth regulators which may be important in restricting cell proliferation in vivo. IFNs can antagonize growth factor-mediated changes in cell proliferation. The studies proposed will clarify mechanisms of IFN-induced growth inhibition in a human tumor cell line.