ROLE OF PLEIOTROPHIN IN BREAST CANCER

这项提案的长期目标是确定和描述 多营养素(PTN)和中期因子(MK)所使用的通路 在人乳腺癌模型中促进肿瘤生长和肿瘤血管生成。 研究人员已经从物理上和功能上剖析了PTN分子 进入两个独立的结构域即信号转换(Ptn氨基酸1-) 和血管生成(PTN氨基酸69-136)。PTN 1-和PTN 69-136信号促进肿瘤建立更具侵袭性的肿瘤生长 已经转化的细胞，但只有PTN 1-能够转化 未转化细胞，建立了PTN1-和PTN69-136信号通路 不同的致癌途径与不同的激活致癌途径协同作用。 Pleiotroin在许多人类乳腺癌和乳腺癌细胞系中表达 乳腺癌，但不在正常乳腺上皮中。构造性表达 PTN只能“部分”转化“正常”乳腺上皮(MM3 MG)细胞， 这表明仅有组成性PTN信号不能改变正常乳房 上皮[细胞]此外，人乳房中PTN信号的中断 组成性表达内源性PTN基因的肿瘤细胞MDA-MB-231 逆转其在裸鼠及PTN1-和PTN体内的侵袭性生长表型 69-136都能促进变形较弱的人乳房的侵略性生长 癌细胞MCF-7。这些结果表明MCF-7细胞已经被激活 与血管生成和转化结构域兼容的致癌途径 PTN基因及构建稳定表达PTN 1-的研究 而PTN 69-136提供了一个递增的“开关”，以促进积极的增长 表型。 MK是PTN生长/分化家族中唯一的另一个成员。它是 在原发乳腺癌和来源于 人类乳腺癌。值得注意的是，一种自然产生的截短突变体MK 1-3，59-121，PTN血管生成结构域(PTN)的结构副本 69-136)在30%的侵袭性乳腺癌组织中检测到，但未检测到 在正常的乳房组织中。MK和MK1-3、59-121都促进更具攻击性 肿瘤生长和肿瘤血管生成(正在进行中) 在MCF-7细胞中组成性表达并接种于裸鼠体内。 为了追求这些成果和长期目标，我们的具体目标是： 一、确定MMTV-PTN 1-、MMTV-PTN 69-136、MMTV-MK的功能增益 1-3，5克。121在转基因小鼠中协同激活的致癌途径和 发展和/或促进肿瘤 鉴定、克隆和鉴定信号分子，通过这些信号分子 PTN信号在人乳腺癌细胞中的转化和/或促肿瘤作用。 拟议中的实验结果可能非常重要。他们会 直接验证PTN和MK是自然产生的启动子的假设 在转基因小鼠模型中乳腺癌侵袭性生长的研究。他们可能会 也识别下游分子在肿瘤促进和潜能中的信号 人类乳腺癌的治疗产品。

The long-range goals of this proposal are to identify and characterize the pathways that are used by pleiotrophin (PTN) and midkine (MK) to promote tumor growth and tumor angiogenesis in human breast cancer models. The investigator has dissected the PTN molecule physically and functionally into two independent domains that signal transformation (PTN amino acids 1-64) and angiogenesis (PTN amino acids 69-136), respectively. Both PTN 1-64 and PTN 69-136 signal tumor promotion to establish more aggressive tumor growth of already transformed cell, but only PTN 1-64 is capable of transforming untransformed cells, establishing that PTN 1-64 and PTN 69-136 signal through different pathways and cooperate with different activated oncogenic pathways. Pleiotrophin is expressed in many human breast cancers and cell lines from breast cancers but not in normal breast epithelium. Constitutive expression of PTN only "partially" transforms "normal" breast epithelial (MM3MG) cells, indicating that constitutive PTN signaling alone cannot transform normal breast epithelia[ cells. Furthermore, disruption of PTN signaling in human breast carcinoma MDA-MB-231 cells which constitutively express the endogenous Ptn gene reverses their aggressive growth phenotype in nude mice and PTN 1-64 and PTN 69-136 both promote aggressive growth of the weakly transformed human breast cancer MCF-7 cells. These results indicate that MCF 7 cells have activated oncogenic pathways compatible with both the angiogenic and transforming domain of PTN and that introduction of constitutive stable expression of both PTN 1-64 and PTN 69-136 provides an incremental "switch" to promote aggressive growth phenotype. MK is the other only member of the PTN growth/ differentiation family. It is also highly expressed in primary breast cancers and cell lines derived from human breast cancers. Remarkably, a naturally occurring truncated mutant MK 1-3, 59-121, a structural counterpart of the PTN angiogenesis domain (PTN 69-136), is detected in 30 % of aggressive human breast cancers tissues but not in normal breast tissues. Both MK and MK1-3, 59-121 promote more aggressive tumor growth and perhaps tumor angiogenesis (in progress) when they are constitutively expressed in MCF-7 cells and inoculated into the nude mouse. To pursue these results and the long-term goals, our Specific Aims are: I. to determine if gain of function of MMTV-PTN 1-64, MMTV-PTN 69-136, MMTV-MK 1-3,5g. 121 cooperate with activated oncogenic pathways in transgenic mice and develop and/or promote tumor II. to identify, clone, and characterize the signaling molecules through which PTN signals transformation and/or tumor promotion in human breast cancer cells. The results of the proposed experiments may be very significant. They will directly test the hypothesis that PTN and MK are naturally occurring promoters of aggressive growth in mammary cancer in transgenic mouse models. They may also identify downstream molecules signaled in tumor promotion and potential therapeutic products in human breast cancer in man.