ROLE OF PLEIOTROPHIN IN BREAST CANCER

本提案的长期目标是确定和描述 多效生长因子（PTN）和中期因子（MK）用于 促进人乳腺癌模型中的肿瘤生长和肿瘤血管生成。 研究者从物理和功能上剖析了PTN分子 转化为两个独立的结构域，其发出转化信号（PTN氨基酸1-64） 和血管生成（PTN氨基酸69-136）。PTN 1-64和PTN 69-136信号肿瘤促进以建立更侵袭性的肿瘤生长。 已经转化的细胞，但只有PTN 1-64能够转化 未转化的细胞，确定PTN 1-64和PTN 69-136通过 不同的途径，并与不同的激活致癌途径合作。 多效生长因子在许多人乳腺癌和乳腺癌细胞系中表达， 乳腺癌，而不是在正常乳腺上皮。的组成型表达 PTN仅“部分”转化“正常”乳腺上皮（MM 3 MG）细胞， 这表明组成性PTN信号传导单独不能将正常乳腺癌转化为乳腺癌， 上皮细胞此外，人乳腺癌中PTN信号传导的中断 组成型表达内源性Ptn基因的癌MDA-MB-231细胞 逆转其在裸小鼠以及PTN 1-64和PTN中的侵袭性生长表型 69-136均促进弱转化的人乳房的侵袭性生长 乳腺癌MCF-7细胞这些结果表明，MCF 7细胞已经激活， 与血管生成和转化结构域相容的致癌途径 以及PTN 1-64组成型稳定表达的引入 PTN 69-136提供了一个增量“开关”，以促进积极的增长 表型 MK是PTN生长/分化家族的另一个唯一成员。是 也在原发性乳腺癌和来源于乳腺癌的细胞系中高度表达。 人类乳腺癌值得注意的是，天然存在的截短突变MK 1-3，59-121，PTN血管生成结构域（PTN）的结构对应物 69-136），在30%的侵袭性人类乳腺癌组织中检测到，但在20%的侵袭性人类乳腺癌组织中检测不到， 在正常的乳腺组织中。MK和MK 1 -3，59-121都促进更积极的 肿瘤生长和可能的肿瘤血管生成（正在进行中）， 在MCF-7细胞中组成型表达并接种到裸鼠中。 为了实现这些成果和长期目标，我们的具体目标是： I.确定MMTV-PTN 1-64、MMTV-PTN 69-136、MMTV-MK的功能是否增益 1- 3.5克。121在转基因小鼠中与激活的致癌途径合作， 发展和/或促进肿瘤 二.识别、克隆和表征信号分子， PTN信号在人乳腺癌细胞中的转化和/或肿瘤促进。 所提出的实验的结果可能是非常重要的。他们将 直接测试PTN和MK是天然存在的启动子的假设 在转基因小鼠模型中乳腺癌的侵袭性生长。他们可能 还确定了在肿瘤促进和潜在的下游分子信号 治疗人类乳腺癌的药物。

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.