MTA1 IN ONCOGENESIS

描述（由申请人提供）：乳腺癌是女性新发癌症病例的主要原因，也是女性癌症死亡的第二大原因（仅次于肺癌）。然而，与乳腺癌相关的高死亡率是由于这些肿瘤有扩散的倾向，而原发肿瘤很小且未被发现。Wnt1和STAT3是人类癌症中的两种主要转化分子，其上游调控的分子机制以及这些癌症的进展和转移目前尚不完全清楚，但据信与主染色质修饰因子的扰动有关。例如，转移性肿瘤抗原1 （MTA1）的过度表达，一种主要的染色质修饰因子，经常与人类乳腺癌的侵袭性临床病程相关。尽管关于MTA1、Wnt1和STAT3的信息显著增长，但关于MTA1和含MTA1的共调节复合物的直接靶点调控乳腺上皮细胞转化和转移的机制仍是未知的，这也是本应用的重点。

DESCRIPTION (provided by applicant): Breast cancer is the leading site of new cancer cases in women and is the second leading cause (after lung cancer) of cancer death among women. The high mortality rate associated with breast cancer, however, is due to a propensity for these tumors to spread while the primary tumors are small and undetected. The molecular mechanisms underlying the upstream regulation of the Wnt1 and STAT3, two major transforming molecules in human cancer and, in turn, progression and metastasis of these cancers are not completely understood at the present time, but believed to involve perturbation of master chromatin modifiers. For example, overexpression of metastatic tumor antigen 1 (MTA1), a master chromatin modifier, is frequently associated with an aggressive clinical course in human breast cancer. Despite the remarkable growth of information about MTA1, Wnt1, and STAT3, knowledge regarding the mechanism by which MTA1 and the direct targets of MTA1-containing coregulatory complexes regulate mammary epithelial cell transformation and metastasis remains elusive, and is the focus of this application. In this context, our recent work suggests that MTA1 deregulation in mammary epithelial cells plays a significant role in stimulating Wnt1 via targeting of specific gene chromatin, namely repressing Six3 (a direct corepressor of Wnt1), and STAT3 chromatin. In addition, for the first time, we discovered that MTA1 is required for breast-to-lung metastasis in a transgenic mouse model. This proposal is designed to establish the mechanism by which MTA1, a physiologic upstream regulator of Wnt1 and STAT3 gene chromatin, contributes to the development of neoplastic phenotypes in mammary epithelial cells and tumors. These findings offer a unique opportunity to study the first upstream common chromatin modifier of two pathways implicated in oncogenesis. Our working hypothesis is that "deregulation of MTA1 results in activation of the Wnt1, and STAT3 pathways, and consequently, confers neoplastic and metastatic properties to breast epithelial cells." To address these hypotheses, our Specific Aims are to: (1) Determine the mechanism of MTA1 regulation of Wnt1 expression, signaling, and functions in mammary epithelial cells; (2) Determine mechanism of MTA1-driven breast-to-lung metastasis; (3) Determine the expression characteristics and significance of MTA1 and its targets/effectors in human breast cancer. An innovative aspect of our proposal is the delineation of the mechanistic and functional significance of the MTA1- Wnt1, and the MTA1-STAT3 pathways in breast cancer cells. These studies will uniquely define the mechanisms of neoplastic and metastatic activities of MTA1. Our proposed research is significant, as the knowledge gained from this research will enhance our understanding of the critical regulatory pathways with established roles in breast cancer progression. In addition, this research will form the basis for new translational advances in identifying novel molecular targets, detecting, and treating breast cancer, by identifying MTA1 as a key master regulatory nodule. PUBLIC HEALTH RELEVANCE: This proposal is based on the original findings that MTA1 is a physiologic modifier of the Wnt1 and STAT3, two gene products implicated in oncogenesis and metastasis. The proposal is designed to establish the mechanism by which MTA1 contributes to the development of tumorigenic phenotypes in mammary epithelial cells and tumors.