IFN-Lambda Signal Transduction

我们的研究表明，IFN-lambda/IL-28维持信号转导和转录激活因子（STAT）1和STAT2的激活时间超过8小时。这与由I型ifn激活的相同stat的激活概况形成对比。我们已经在人类2fTGH纤维肉瘤和HaCat永生化皮肤角质形成细胞细胞系以及B16小鼠黑色素瘤细胞系中证明了这一点。此外，IFN-lambda在诱导HaCat的抗增殖作用方面优于IFN-alpha，这与IFN-alpha处理未检测到的凋亡细胞的检测结果相似。与ifn - α形成鲜明对比的是，生化分析显示IFN-lambda维持STAT1的激活不需要合成新的蛋白质。尽管这两种ifn对肿瘤细胞都有抗增殖作用，但我们的研究表明，这两种细胞因子如何以不同的方式激活Jak/STAT通路。为了比较IFN-lambda的体内抗肿瘤作用，我们使用人类异种移植肿瘤模型，用携带ifn - β或IFN-lambda的免疫功能低下的RagKO小鼠，通过向其注射表达致癌Ras的人角质形成细胞诱导的皮下肿瘤。每种细胞因子单独抑制肿瘤的进一步生长。然而，ifn - β在缩小已形成肿瘤的大小方面更有效。我们正在进行的工作是同时使用这两种细胞因子，并确定它们联合使用时是否可以增强抗肿瘤作用。这些初步发现强调了IFN-lambda在癌症治疗中的潜在治疗用途。我们的研究与其他报告的不同之处在于，我们使用重组蛋白而不是通过基因工程来分泌IFN-lambda的肿瘤细胞。现在我们通过研究和比较IFN-lambda和ifn - α的反应性来扩展这项工作，首先检测来自同一患者的配对原发性和几种转移性黑色素瘤细胞系中ifn诱导的STAT激活。到目前为止，来自3名不同患者的原发性黑色素瘤只对ifn - α有反应，而对IFN-lambda没有反应，这表明这些肿瘤可能不表达IFN-lambda受体。令人惊讶的是，虽然所有转移性肿瘤都对ifn - α有反应，但只有一些转移性肿瘤对IFN-lambda有反应。从这项初步研究中，我们得出以下结论：(1)对IFN-lambda有反应的转移性肿瘤也必须对ifn - α / β有反应；(2)表面IFN-lambda受体可能被甲基化或沉默，但可以在转移性肿瘤上表达——一旦我们有FACS抗体来测量该受体的表达，我们将验证这一观察结果。(3)转移性黑色素瘤肿瘤对I型和III型ifn的反应是异质的。因此，在癌症治疗中加入IFN-lambda可能会使患者受益。

Our studies show that IFN-lambda/IL-28 sustains the activation of the signal transducers and activators of transcription (STAT)1 and STAT2 for longer than 8 hours. This is in contrast from the activation profile of these same STATs that are activated by type I IFNs. We have shown this in the human 2fTGH fibrosarcoma and HaCat immortalized skin keratinocyte cell lines and in B16 mouse melanoma cell line. In addition, IFN-lambda was superior than IFN-alpha in inducing an antiproliferative effect in HaCat, which paralleled detection of apoptotic cells that were not detected with IFN-alpha treatment. In stark contrast with IFN-alpha, biochemical analysis revealed that maintainance of STAT1 activation by IFN-lambda did not require new protein synthesis. Although both IFNs exert an antiproliferative effect on tumor cells, our study shows how these two cytokines do not activate the Jak/STAT pathway in the same manner. To compare the invivo antitumor effects of IFN-lambda, using a human xenograft tumor model, we have treated immunocompromised RagKO mice with either IFN-beta or IFN-lambda carrying established subcutaneous tumors induced by injecting them with human keratinocyte cells expressing oncogenic Ras. Each cytokine alone inhibited further tumor growth. However, IFN-beta was more efficient in shrinking the size of the established tumors. Our ongoing work is to use both cytokines together and determine if their antitumor effect can be augmented when used in combination. These initial findings highlight the potential therapeutic use of IFN-lambda in the treatment of cancer. Our study differs from other reports as we employed recombinant protein rather than tumor cells genetically engineered to secret IFN-lambda. Now we are expanding this work by studying and comparing IFN-lambda to IFN-alpha responsiveness by first detecting IFN-induced STAT activation in paired primary and several metastatic melanoma cell lines that were derived from the same patient. Thus far primary melanoma tumors from 3 different patients only respond to IFN-alpha but not to IFN-lambda thus suggesting that these tumors may not express IFN-lambda receptors. Surprisingly, while all metastatic tumors respond to IFN-alpha, only some gained responsiveness to IFN-lambda. From this initial study, we conclude with the following observations: (1) metastatic tumors that respond to IFN-lambda must also respond to IFN-alpha/beta; (2) Surface IFN-lambda receptors might be methylated or silenced but can be expressed on metastatic tumors-an observation that we will validate once we have FACS antibodies to measure expression of this receptor and (3)metastatic melatoma tumors are heterogeneous in their response to type I and type III IFNs. Therefore, patients may benefit from including IFN-lambda in their cancer treatment.