Lokshin A, Mayotte J E, Levitt M L
Department of Human Oncology, Medical College of Pennsylvania, Pittsburgh, USA.
J Natl Cancer Inst. 1995 Feb 1;87(3):206-12. doi: 10.1093/jnci/87.3.206.
Non-small-cell lung cancer (NSCLC) is one of the leading causes of cancer-related mortality due largely to the failure of systemic chemotherapy. Thus, new therapeutic paradigms involving the manipulation of normal physiologic growth-regulatory mechanisms, such as terminal cellular differentiation or programmed cell death, are being explored. Interferons may function as antineoplastic agents, in part because of their effects on cell proliferation and differentiation. We have previously demonstrated the antiproliferative and differentiating effects of interferon beta (IFN beta).
The present investigation was designed to study the mechanism of IFN beta on squamous differentiation and/or programmed cell death in cultured NSCLC cells.
Cross-linked envelope competence and transglutaminase expression and activity were measured in three NSCLC cell lines (NCI-H226, NCI-H358, and NCI-H596) as common markers for squamous differentiation and programmed cell death. DNA fragmentation, as determined by gel electrophoretic analysis, served as a marker for programmed cell death. In addition, the expression of several regulatory and differentiation-related genes (measured by Northern blot analysis of messenger RNA levels) as well as protein kinase C activity was measured to begin to explore possible mechanisms of IFN beta activity.
IFN beta-induced cross-linked envelope competence occurred in cell lines with squamous features (NCI-H226 and NCI-H596); conversely, DNA fragmentation occurred in cell lines with glandular features (NCI-H358 and NCI-H596). Stimulation of cross-linked envelope competence by IFN beta was associated with the induction of tissue transglutaminase activity. Both of these parameters were protein-synthesis independent. As previously observed for NCI-H596, IFN beta suppressed the growth of the other two cell lines. Total protein kinase C activity was not altered. Expression of a variety of possibly relevant oncogenes and other genes was variably altered by IFN beta.
IFN beta induces programmed cell death in NSCLC cell lines in a phenotype-specific manner. The programmed cell death pathway represented by cross-linked envelope competence is dependent on the expression of the squamous phenotype and is protein-synthesis independent, suggesting post-translational mechanisms. In addition, squamous differentiation itself may be induced. Changes in gene expression, while not necessary for induction of cross-linked envelope competence, may be involved in other aspects of cellular homeostasis, such as growth suppression.
By inducing terminal cellular differentiation or programmed cell death, IFN beta may be therapeutically useful in NSCLC. The post-translational nature of IFN beta-induced effects suggests that it will be best used in combination with other agents that can regulate these cellular pathways at the pretranslational level, increasing the proportion of cells capable of being driven to a terminal state by this biotherapeutic agent.
非小细胞肺癌（NSCLC）是癌症相关死亡的主要原因之一，这主要归因于全身化疗的失败。因此，人们正在探索涉及操纵正常生理生长调节机制（如终末细胞分化或程序性细胞死亡）的新治疗模式。干扰素可能作为抗肿瘤药物发挥作用，部分原因是它们对细胞增殖和分化的影响。我们之前已经证明了干扰素β（IFNβ）的抗增殖和分化作用。
本研究旨在探讨IFNβ对培养的NSCLC细胞中鳞状分化和/或程序性细胞死亡的作用机制。
在三种NSCLC细胞系（NCI-H226、NCI-H358和NCI-H596）中检测交联包膜能力和转谷氨酰胺酶的表达及活性，作为鳞状分化和程序性细胞死亡的常见标志物。通过凝胶电泳分析确定的DNA片段化作为程序性细胞死亡的标志物。此外，检测了几种调节和分化相关基因的表达（通过信使RNA水平的Northern印迹分析测量）以及蛋白激酶C活性，以初步探索IFNβ活性的可能机制。
IFNβ诱导的交联包膜能力出现在具有鳞状特征的细胞系（NCI-H226和NCI-H596）中；相反，DNA片段化出现在具有腺状特征的细胞系（NCI-H358和NCI-H596）中。IFNβ对交联包膜能力的刺激与组织转谷氨酰胺酶活性的诱导有关。这两个参数均不依赖于蛋白质合成。如之前在NCI-H596中观察到的，IFNβ抑制了其他两种细胞系的生长。总蛋白激酶C活性未改变。IFNβ对多种可能相关的癌基因和其他基因的表达有不同程度的改变。
IFNβ以表型特异性方式诱导NSCLC细胞系中的程序性细胞死亡。以交联包膜能力为代表的程序性细胞死亡途径依赖于鳞状表型的表达，且不依赖于蛋白质合成，提示存在翻译后机制。此外，可能诱导了鳞状分化本身。基因表达的变化虽然不是诱导交联包膜能力所必需的，但可能参与细胞内稳态的其他方面，如生长抑制。
通过诱导终末细胞分化或程序性细胞死亡，IFNβ在NSCLC治疗中可能具有应用价值。IFNβ诱导作用的翻译后性质表明，它最好与其他能够在翻译前水平调节这些细胞途径的药物联合使用，从而增加能够被这种生物治疗药物驱动至终末状态的细胞比例。
