MAMMARY CARCINOGENESIS--THE ROLE OF PLEIOTROPHIN

乳腺癌发生：多效营养因子的作用。乳腺癌生长 并且转移需要肿瘤细胞之间的生长因子信号， 周围正常的宿主组织我们建议， 多肽生长因子多效生长因子（PTN）在 乳腺癌的发生以及乳腺癌的生长和转移 癌这一假说是基于PTN的生物学效应 在选定的肿瘤模型中，PTN mRNA的高水平表达在60%的肿瘤中， 乳腺癌患者的肿瘤样品及其上调 致癌物诱发的啮齿动物乳腺癌。此外，PTN是 在未成熟的小鼠乳腺中高度表达， 致癌物质，并在经历过 怀孕和防止致癌。最后，活动 PTN在体外内皮细胞上的表达表明PTN可以作为一种 血管生成因子在肿瘤进展中的作用。为了支持这一作用， PTN作为一种血管生成因子，减少了组成性表达的 PTN靶向核酶对人肿瘤细胞系内源性rib mRNA表达的影响 即使在体外生长时， 肿瘤细胞不受影响。 基于这些初步研究，我们希望阐明PTN的作用 在乳腺癌进展和乳腺癌发生中， 最终目标是开发更好的预后标志物以及新的 治疗策略 根据目标1，我们将研究乳腺癌患者血清PTN水平是否 患者可以预测其疾病的长期结果， 对治疗的反应。我们将使用10年以上患者的样本 从我们的血清库核心设施中提取的样本下 目的2：研究激素调节对PTN的影响程度 在乳腺成熟和乳腺癌发生过程中的表达 在啮齿动物模型中。我们将研究类固醇激素的影响， 视黄酸受体配体对PTN表达和乳腺的影响 生物学或动物和器官培养中的致癌作用。根据目标3 我们将研究在多大程度上维持高水平的rib表达， 会影响乳腺成熟，激素反应， 乳腺不同阶段对致癌物的敏感性 成熟为了实现这一点，我们将PTN作为转基因在小鼠中表达， 在四环素调节的启动子下。我们将研究 用激素刺激转基因动物（和器官外植体） 刺激物以及致癌物。在目标4下，我们将研究 内源性PTN表达的降低程度将影响乳腺 生理学和病理学。我们将使用核糖酶靶向肋骨， 以实现这一目标。我们将产生表达PTN-targeted 受四环素调控的启动子控制的核酶， 研究怀孕期间腺体的自发成熟， 内源性PTN的激素和致癌物挑战的影响 被核酶转基因抑制。根据目标5，我们将开发基因 转移载体与核酶在体内靶向RIB表达。我们将 使用腺病毒和疱疹病毒载体进行基因转移。

Mammary Carcinogenesis: The Role of Pleiotrophin. Breast cancer growth and metastasis requires growth factor signals between the tumor cells and the normal surrounding host tissue. We propose that the secreted polypeptide growth factor pleiotrophin (PTN) plays a major role in mammary carcinogenesis as well as in the growth and metastasis of breast cancer. This hypothesis is based on the biological effects of PTN expression in selected tumors models, the high levels of PTN mRNA in 60% of tumor samples from breast cancer patients and on its upregulation during carcinogen-induced rodent mammary cancer. Furthermore, PTN is highly expressed in immature mouse mammary glands that are sensitive to carcinogens and is downregulated permanently in mice that have undergone pregnancy and are protected against carcinogenesis. Finally, the activity of PTN on endothelial cells in vitro suggests that PTN can serve as an angiogenesis factor during tumor progression. In support of this role of PTN as an angiogenesis factor, reduction of constitutively expressed endogenous rib mRNA in human tumor cell lines by PTN-targeted ribozymes reduced tumor growth and metastasis even when in vitro growth of the tumor cells remained unaffected. Based on these preliminary studies, we wish to elucidate the role of PTN in breast cancer progression and in mammary carcinogenesis with the ultimate goal to develop better prognostic markers as well as novel therapeutic strategies. Under aim 1 we will study whether serum levels of PTN in breast cancer patients can predict long term outcome of their disease an-or the response to therapy. We will use samples from patients with over 10 years of follow-up from our serum bank core facility for this analysis. Under aim 2 we will study to what extent hormonal regulation affects PTN expression in mammary gland maturation and during mammary carcinogenesis in rodent models. We will study the influence of steroid hormones and retinoid acid receptor ligands on PTN expression and on mammary gland biology or carcinogenesis in animals and in organ culture. Under aim 3 we will study to what extent sustained high levels of expression of rib will affect mammary gland maturation, hormonal responsiveness and susceptibility to carcinogens at different stages of mammary gland maturation. To achieve this, we will express PTN as a transgene in mice under a tetracycline-regulated promoter. We will study the effects of a challenge of the transgenic animals (and of organ explants) with hormonal stimuli as well as with carcinogens. Under aim 4 we will study to what extent reduction of endogenous PTN expression will affect mammary gland physiology and pathology. We will use ribozyme-targeting of rib to achieve this goal. We will generate mice expressing PTN-targeted ribozymes under the control of a tetracycline-regulated promoter and study spontaneous gland maturation during pregnancy as well as the effects of hormonal and carcinogen challenges with the endogenous PTN suppressed by the ribozyme transgene. Under aim 5 we will develop gene transfer vectors to target rib expression with ribozymes in vivo. We will use adenovirus- and herpes virus-based vectors for gene transfer.