DEVELOPMENT OF A STOCHASTIC MOUSE TO STUDY BREAST CANCER

开发用于研究乳腺癌的随机小鼠

• 批准号: 6175029
• 负责人: Jeffrey Mark Rosen
• 金额: $ 7.85万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-14 至 2002-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6175029
• 关键词: bone neoplasms; breast neoplasms; disease /disorder model; genetically modified animals; laboratory mouse; metastasis; model design /development; parathyroid hormone related protein; protooncogene; tissue /cell culture

Even though 70 percent patients dying with breast cancer have osteolytic bone metastasis, a thorough understanding of the biology of skeletal metastasis remains elusive due to the lack of appropriate animal models that mimic the clinical experience of metastasis of primary breast tumors to the bone. The mouse has been used as a model for a number of individual steps in the metastatic cascade, but a mouse model for the entire process i.e. development of the primary tumor in the breast to its metastases to distant organs like bone, has not been developed. Although, some transgenic mouse models of breast cancer have been shown to metastasize extensively, none of them metastasize to the bone. Overexpression and amplification of the neu (c-erbB2, ERBB2) proto-oncogene have been implicated in the development of aggressive human breast cancer. Targeted expression of the neu proto-oncogene specifically to the mouse mammary gland (under the control of a MMTV promotor) induces metastatic disease after a mean latency of 205 days. On the other hand, it is generally recognized that ostoclastic bone resorption is necessary before expansion of tumor cells from bone marrow to bone. In the case of breast cancer, this final step is mediated by osteoclasts that are stimulated by local production of the tumor peptide parathyroid hormone - related peptide (PTH-rp). Some of the evidence which supports this hypothesis are: patients with PTH-rp positive breast carcinomas are more likely to develop bone metastasis. In addition, breast carcinoma metastatic to bone express PTH-rp in greater than 90 percent of cases, compared with only 17 percent of metastases to nonbone sites. It has also been reported that expression of PTHrp in MDA 231 human breast cancer cells increased osteolytic bone metastasis while neutralising antibodies to PTHrp markedly suppressed them. Thus, PTHrp plays an important role in the process of bone metastasis. Taken together, both the clinical and experimental data suggest that if neu-expressing breast carcinoma cells are engineered to overexpress PTHrp, they may be able to home to the bone and metastasize. With this hypothesis, the overall objective of this proposal is to develop a stochastic model of breast cancer metastasis to the bone and to identify downstream targets that mediate the activity of ERBB2 and PTHrp during breast cancer metatatic progression. We propose to test this hypothesis both in vitro, using a cell culture model and in vivo by generating neu/PTHrp expressing bigenic mice. Our specific aims are: Specific Aim 1: To develop a mouse model of breast cancer metastasis from the mammary gland to the bone using an in vitro mouse cell culture model that is engineered to overexpress both neu and PTHrp. Specific Aim 2: To determine, if, targeted expression of PTHrp and neu specifically to the mouse mammary epithelial cells facilitates bone metastases formation in these animals. Development of such a model that overexpresses proto-oncogene neu and is engineered to overproduce PTHrp would most closely mimic human breast cancer progresion and provide an improved model for preclinical studies of therapeutic agents. It will also provide a unique platform to investigate cellular events involved in site-specific metastasis of breast cancer to the bone.

即使70％因乳腺癌死亡的患者患有骨化骨转移，但由于缺乏合适的动物模型，这些模型模仿了原发性乳腺肿瘤转移到骨骼的临床经验，对骨骼转移的生物学仍然难以捉摸。 该小鼠已被用作转移级联反应中多个单个步骤的模型，但是尚未开发出整个过程的小鼠模型，即乳房中原发性肿瘤的发展到其转移到骨骼（如骨骼）的转移。 虽然，一些乳腺癌的转基因小鼠模型已被证明可以广泛转移，但它们都没有转移到骨骼。 NEU（C-ERBB2，ERBB2）原癌基因的过表达和扩增与侵略性人类乳腺癌的发展有关。 针对小鼠乳腺（在MMTV启动子的控制下），针对NEU原型癌基因的靶向表达会导致平均潜伏期205天后诱导转移性疾病。 另一方面，通常认为在肿瘤细胞从骨髓到骨骼扩张之前，必须认识到骨质碎裂的骨吸收。 在乳腺癌的情况下，这一最后一步是由破骨细胞介导的，骨细胞是由局部产生的肿瘤肽甲状旁腺激素 - 相关肽（PTH -RP）所刺激的。 支持该假设的一些证据是：患有PTH-RP阳性乳腺癌的患者更有可能发展骨转移。 此外，大于90％的病例中乳腺癌向骨头表达PTH-RP的转移，而非骨位点的转移仅17％。 还据报道，PTHRP在MDA 231人类乳腺癌细胞中的表达增加了骨骨转移，同时中和对PTHRP的抗体显着抑制了它们。 因此，PTHRP在骨转移过程中起重要作用。综上所述，临床和实验数据都表明，如果表达NEU的乳腺癌细胞以过表达PTHRP，则它们可能能够回家并转移。 有了这一假设，该提案的总体目的是开发向骨骼的乳腺癌转移的随机模型，并确定介导乳腺癌转向过程中ERBB2和PTHRP活性的下游靶标。 我们建议在体外，使用细胞培养模型和体内通过产生表达bigenic小鼠的NEU/PTHRP来检验这一假设。 我们的特定目的是：特定目标1：使用体外小鼠细胞培养模型开发从乳腺到骨骼的小鼠乳腺癌转移模型，该模型设计为过表达NEU和PTHRP。 具体目的2：确定，是否针对PTHRP和NEU的针对小鼠乳腺上皮细胞的靶向表达促进了这些动物中骨转移的形成。这种模型过表达原始癌基因NEU并设计为过量生产PTHRP的模型将最紧密地模仿人类乳腺癌的前期，并为治疗剂的临床前研究提供了改进的模型。 它还将提供一个独特的平台，以研究乳腺癌特异性转移涉及的细胞事件。