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SV 40是导致恶性间皮瘤（MM）的共同致癌物。该假设基于使用人间皮细胞（HM）的体外实验和仓鼠体内实验。我们发现石棉和SV 40小t抗原突变体都不能引起HM恶性转化。然而，当HM暴露于石棉和SV 40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，心脏内注射SV 40小t突变体和胸膜内和腹膜内注射石棉对仓鼠具有强效共致癌作用。我们的研究结果表明，暴露于石棉和SV 40的个体患间皮瘤的风险增加。在这里，我们要研究的共同致癌机制。我们建议在人类和仓鼠间皮瘤细胞的组织培养中，以及仓鼠和人类间皮瘤活检中进行这些研究。在目的1中，我们将在组织培养中确定TNF-α、PDGF和TGF-β在HM中SV 40-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，TNF-α的表达和受体诱导HM石棉暴露或SV 40感染。HM暴露于TNF-α诱导NF-κ β活化，其在肿瘤发生中起重要作用。同时，我们正在研究SV 40和石棉对Ras-ERK途径和AP-1诱导的影响，因为我们发现，SV 40和石棉在组织培养中诱导HM中的ERK 1/2和下游效应物。我们的假设是，所有这些机制是相互关联的，我们将研究这些机制在SV 40石棉共致癌的生物学意义。在目标2A中，将在我们用石棉、SV 40和SV 40小t突变体加石棉在仓鼠中诱导的MM的冷冻标本中研究目标1中研究的相同细胞因子和基因通路，并比较结果。通过比较体外数据（目的I），与实验MM模型（目的2A）中产生的数据，其中暴露在我们的控制之下，我们将在许多可能的候选基因通路中确定与MM发病机制和SV 40-石棉发病机制和共致癌作用最相关的那些。将通过研究在体外（目的1）和仓鼠MM（目的2A）中鉴定的相同细胞因子和基因通路（目的2B），在38份冷冻MM活检和匹配肺组织的独特集合中验证结果。在这38个样本中，我们确定了SV 40状态和石棉暴露的类型和数量。最后，在目标3中，我们将尝试建立一个SV 40-石棉小鼠肿瘤模型，类似于我们在hasmters中建立的模型。由于大量的小鼠试剂（单克隆、转基因小鼠、敲除小鼠等），小鼠模型的可用性对于未来的机制和实验治疗方法是理想的。预计本申请中提出的实验结果将为设计MM的新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.