IFN-lambda signal transduction

我们的研究表明，干扰素-lambda/IL-28维持信号转导和转录激活因子(STAT)1和STAT2的激活长达8小时以上。这与由I型IFN激活的这些相同统计信息的激活配置文件形成对比。我们已经在人2fTGH纤维肉瘤和HaCat永生化皮肤角质形成细胞系以及B16小鼠黑色素瘤细胞系中证明了这一点。此外，干扰素-lambda在诱导HaCat细胞增殖方面优于干扰素-α，这与用干扰素-α处理未检测到的凋亡细胞的检测平行。与干扰素-α形成鲜明对比的是，生化分析表明，干扰素-lambda维持STAT1的激活不需要新的蛋白质合成。虽然这两种干扰素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并不以相同的方式激活JAK/STAT通路。为了比较干扰素-lambda的体内抗肿瘤作用，利用人异种移植瘤模型，我们用干扰素-β或干扰素-lambda治疗免疫低下的RagKO小鼠，这些小鼠通过注射表达致癌基因RAS的人角质形成细胞来诱发已建立的皮下肿瘤。每种细胞因子单独抑制肿瘤的进一步生长。然而，干扰素-β在缩小已建立的肿瘤大小方面更有效。我们正在进行的工作是将这两种细胞因子一起使用，并确定当它们联合使用时，它们的抗肿瘤作用是否可以增强。这些初步发现突出了干扰素-lambda在癌症治疗中的潜在治疗用途。我们的研究与其他报告不同，因为我们使用的是重组蛋白，而不是基因工程的肿瘤细胞来分泌干扰素-lambda。现在，我们正在通过研究和比较干扰素-lambda和干扰素-α的反应性来扩展这项工作，首先检测来自同一患者的成对的原发和转移的黑色素瘤细胞系中干扰素诱导的STAT激活。到目前为止，来自3个不同患者的原发黑色素瘤只对干扰素-α有反应，而对干扰素-lambda没有反应，因此提示这些肿瘤可能不表达干扰素-lambda受体。令人惊讶的是，虽然所有转移性肿瘤对干扰素-α都有反应，但只有一些肿瘤对干扰素-波长有反应。从这项初步研究中，我们得出以下观察结论：(1)对干扰素-lambda有反应的转移瘤也必须对干扰素-α/β有反应；(2)表面干扰素-lambda受体可能被甲基化或沉默，但可在转移瘤上表达--一旦我们有FACS抗体来检测该受体的表达，我们就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的反应是不同的。因此，患者可能受益于将干扰素-lambda纳入他们的癌症治疗。

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.