TGF-Beta and Inflammation in Gastric Cancer

描述（由申请人提供）：TGF-？作为细胞生长和炎症的主要调节因子，主要以由TGF-？同型二聚体TGF-？前肽二聚体和潜伏TGF-？结合蛋白（LTBP），它是二硫键结合到每个前肽链上。前肽与TGF-？尽管前肽和TGF-？已被切割，生成TGF-？潜在的。TGF - ?必须从LLC中释放出来才能与其受体结合。一小部分潜在的TGF-？在没有LTBP的情况下与其前肽复合物分泌，称为小潜伏复合物（SLC）。检测活性TGF-？在炎症和肿瘤产生方面，我们产生了突变小鼠（Tgfb1C33S/C33S和Tgfb1-/C33S），其中TGF-？与LTBP结合的1个前肽被丝氨酸取代。这个突变的TGF-？1前肽不能与LTBP结合。因此，分泌的潜伏TGF-？1与LTBP结合，但LTBP和SLC均正常分泌。Tgfb1C33S/C33S小鼠出现多器官炎症，发生胃、直肠和肛门肿瘤，3-4个月死亡。该表型与Tgfb1-/-小鼠相似，除了Tgfb1C33S/C33S炎症表型较轻，但肿瘤表型比Tgfb1-/-表型强。Tgfb1-/C33S小鼠在12周龄时100%发生胃腺癌，并且与Tgfb1C33S/C33S小鼠相比具有更强的炎症反应。我们的小鼠也感染了幽门螺杆菌，这是人类发生胃癌的主要危险因素。因此，Tgfb1-/C33S小鼠为研究胃腺癌诱导及炎症反应参与肿瘤发生提供了新的模型系统。使用本申请中描述的Tgfb1-/C33S小鼠，我们将确定炎症对肿瘤产生的贡献-特别是胃腺癌，胃肠道上皮细胞增殖和凋亡的变化，炎症反应在肿瘤诱导中的作用，肿瘤产生对幽门螺杆菌感染的潜在需求，以及肿瘤细胞的来源。我们将结合小鼠遗传学、细胞生物学和生物化学来回答这些问题。实验的成功完成将为了解胃肿瘤的发生提供重要的信息。这些信息可能为胃肿瘤的治疗干预或预防提供见解。公共卫生相关性：胃肿瘤是全球癌症死亡的第二大原因，了解潜伏TGF-？有助于这种肿瘤的产生，可能对诊断和治疗产生影响。我们培育的突变小鼠为研究胃腺癌的快速形成提供了一个新的系统。此外，这些小鼠可能有助于研究炎症性肠病以及TGF-？生物学。

DESCRIPTION (provided by applicant): TGF-?, a major regulator of cell growth and inflammation, is secreted primarily as a large latent complex (LLC) consisting of the TGF-? homodimer, the TGF-? propeptide dimer, and a single molecule of the latent TGF-? binding protein (LTBP), which is disulfide bonded to each of the propeptide chains. Association of the propeptide with TGF-? even though the bond between propeptide and TGF-? has been cleaved, renders the TGF-? latent. TGF-? must be freed from the LLC to bind to its receptors. A minor fraction of the latent TGF-? is secreted complexed to its propeptide in the absence of LTBP and is called the small latent complex (SLC). To examine the effect of decreased production of active TGF-? on inflammation and tumor production, we generated mutant mice (Tgfb1C33S/C33S and Tgfb1-/C33S) in which the cysteines in the TGF-?1 propeptide that bind to LTBP were replaced by serines. This mutant TGF-?1 propeptide cannot bind to LTBP. Thus, none of the secreted latent TGF-?1 is bound to an LTBP, but both LTBP and SLC are secreted normally. Tgfb1C33S/C33S mice have multi-organ inflammation, develop tumors of the stomach, rectum and anus, and die by 3-4 months. This phenotype resembles that of the Tgfb1-/- mouse except that the Tgfb1C33S/C33S inflammatory phenotype is milder but the tumor phenotype stronger than the Tgfb1-/- phenotypes. 100% of Tgfb1-/C33S mice develop gastric adenocarcinomas by 12 weeks of age and have a stronger inflammatory response compared to Tgfb1C33S/C33S mice. Our mice are also infected with Helicobacter, a major risk factor for the development of gastric cancer in humans. Thus, Tgfb1-/C33S mice provide a new model system to study gastric adenocarcinoma induction as well as the participation of the inflammatory response in tumorigenesis. Using Tgfb1-/C33S mice as described in this application, we will establish the contribution of inflammation to tumor production - specifically gastric adenocarcinomas, the changes in cell proliferation and apoptosis in the GI epithelium, the role of the inflammatory response in tumor induction, the potential requirement for Helicobacter infection for tumor production, and the source of the tumor cells. We will use a combination of mouse genetics, cell biology, and biochemistry to answer these questions. The successful completion of the proposed experiments will provide information critical to the understanding of the generation of gastric tumors. Such information may yield insights for therapeutic intervention or prevention of gastric tumors. PUBLIC HEALTH RELEVANCE: Gastric tumors are the second leading cause of cancer death worldwide and understanding how the activation of latent TGF-? contributes to the generation of this tumor may have impact for diagnosis and treatment. The mutant mice we have produced provide a novel system for the study of the rapid formation of gastric adenocarcinomas. In addition, these mice may be useful for the study of inflammatory bowel disease as well as other aspects of TGF-? biology.