Role of Cell Mediators in Asbestos-SV40 Carcinogenesis

描述（由申请人提供）：我们的假设是石棉和SV40是导致恶性间皮瘤（MM）的共同致癌物。这一假设是基于人类间皮细胞（HM）的体外实验和仓鼠体内实验。我们发现石棉和SV40小t抗原突变体都不能引起HM的恶性转化。然而，当HM同时暴露于石棉和SV40小t突变体时，发生恶性转化和病灶形成。此外，初步结果表明，SV40小t突变体心内注射、石棉胸膜和腹腔内注射对仓鼠有明显的共致癌作用。我们的研究结果表明，同时暴露于石棉和SV40的个体患间皮瘤的风险增加。在这里，我们想研究共同致癌的机制。我们建议在组织培养的人和仓鼠间皮细胞中进行这些研究，并在仓鼠和人间皮瘤活检中进行这些研究。在Aim 1中，我们将在组织培养中确定tnf - α、PDGF和TGF- β在HM中sv40 -石棉共致癌中的生物学效应。在初步结果中，我们发现我们的间皮细胞表达这些细胞因子的受体。我们还发现，在石棉暴露或SV40感染后，HM中tnf - α的表达和受体被诱导。HM暴露于tnf - α诱导的nf - kβ活化在肿瘤发生中起重要作用。同时，我们正在研究SV40和石棉对Ras-ERK通路和AP-1诱导的影响，因为我们发现SV40和石棉在组织培养中都能诱导HM中的ERK1/2和下游效应物。我们的假设是所有这些机制都是相互关联的，我们将研究这些机制在sv40 -石棉共致癌中的生物学意义。在Aim 2A中，将在我们用石棉、SV40和SV40小t突变体加石棉诱导的仓鼠MM的冷冻标本中研究Aim 1中研究的相同的细胞因子和基因途径，并比较结果。通过比较体外数据（aim I）与我们控制暴露的实验性MM模型（aim 2A）中产生的数据，我们将在许多可能的候选基因途径中确定与MM发病机制和sv40 -石棉发病机制和共致癌机制最相关的基因途径。研究结果将通过研究在体外（Aim 1）和仓鼠MM （Aim 2A）中鉴定的相同的细胞因子和基因通路来验证，这些细胞因子和基因通路是在38个冷冻MM活检组织和匹配的肺组织（Aim 2B）中鉴定的。在这38个样品中，我们确定了SV40状态和石棉暴露的类型和数量。最后，在Aim 3中，我们将尝试建立sv40 -石棉小鼠肿瘤模型，类似于我们在仓鼠中建立的模型。由于大量的小鼠试剂（单克隆、转基因小鼠、基因敲除小鼠等），小鼠模型的可用性将是未来机制和实验性治疗方法的理想选择。预计本应用程序中提出的实验结果将为设计新的MM预防和治疗方法提供信息。

DESCRIPTION (provided by applicant): Our hypothesis is that asbestos and SV40 are co-carcinogens in causing malignant mesothelioma (MM). This hypothesis is based on in vitro experiments using human mesothelial cells (HM) and in vivo experiments in hamsters. We found that neither asbestos nor SV40 small t antigen mutants could cause HM malignant transformation. However, when HM were exposed to both asbestos and SV40 small t mutants, malignant transformation and focus formation occurred. Moreover, preliminary results demonstrated a potent co-carcinogenic effect in hamsters coinjected with SV40 small t mutant intracardially and with asbestos intrapleurally and intraperitoneally. Our findings suggest that individuals exposed to both asbestos and SV40 are at increased risk of developing mesothelioma. Here we want to study the mechanisms of co-carcinogenesis. We propose to conduct these studies in human and in hamster mesothelial cells in tissue culture, and in hamster and human mesothelioma biopsies. In Aim 1 we will determine the biological effect of TNF-alpha, PDGF and TGF- beta in SV40-asbestos co-carcinogenesis in HM in tissue culture. In preliminary results we found that our mesothelial cells express receptors for these cytokines. We also found that TNF-alpha expression and receptor are induced in HM following asbestos exposure or SV40 infection. HM exposure to TNF-alpha induced NF-kbeta activation which plays an important role in oncogenesis. In parallel we are studying the effect of SV40 and asbestos on the Ras-ERK pathways and AP-1 induction, because we found that both, SV40 and asbestos induce ERK1/2 and downstream effectors in HM in tissue culture. Our hypothesis is that all these mechanisms are inter-related and we will study the biological significance of these mechanisms in SV40-asbestos co-carcinogenesis. In Aim 2A, the same cytokines and gene pathways studied in Aim 1, will be investigated in frozen specimens from MM we induced in hamster with asbestos, SV40, and SV40 small t mutant plus asbestos, and the results compared. By comparing the in vitro data (aim I), with those produced in an experimental MM model (Aim 2A) in which exposure, was under our control, we will identify among many possible candidate gene pathways, those that are most relevant to MM pathogenesis and to SV40-asbestos pathogenesis and co-carcinogenesis. The results will be validated by studying the same cytokines and gene pathways identified in vitro (Aim 1) and in hamster MM (aim 2A) in a unique collection of 38 frozen MM biopsies and matching lung tissue (Aim 2B). In these 38 samples we have determined SV40 status and type and amount of asbestos exposure. Finally, in Aim 3 we will attempt to establish an SV40-asbestos mouse tumor model, similar to the one we established in hasmters. The availability of a mouse model would be ideal for future mechanistic and experimental therapeutic approaches because of the large number of mouse reagents (monoclonals, transgenic mice, knock-out mice, etc.). It is anticipated that the results of the experimens proposed in this application will provide information to design novel preventive and therapeutic approaches for MM.