Identification of a noval oncogene using validation-based insertional mutagenesis

描述（由申请人提供）：使用人乳腺上皮细胞（HMEC），我们对导致恶性转化的改变进行了正向遗传筛选，并鉴定了一种新的癌基因，命名为FAM 83 B。FAM 83 B的N-末端编码PLD基序，这对于FAM 83 B介导的转化是必需的和充分的。PLD活性升高通过增加磷脂酸（PA）的产生而促进肿瘤发生，磷脂酸是参与调节mTOR和MAPK信号传导的有效第二信使，两者在表达FAM 83 B的细胞中被显著激活。从具有升高的EGFR或HER 2的肿瘤衍生细胞或从由活化的RAS转化的HMEC中消融FAM 83 B抑制了它们的增殖、锚定非依赖性生长和致瘤性，支持FAM 83 B作为关键EGFR/RAS信号传导中介的作用。结合对人类肿瘤标本中FAM 83 B表达的分析，揭示了其在多种人类癌症中的过表达，我们的结果表明FAM 83 B代表了一种参与上调MAPK和mTOR信号传导的新型癌蛋白。该提案的目标是确定FAM 83 B参与MAPK和mTOR信号传导，并检查人类癌症标本以将FAM 83 B表达与这些高度重要的信号级联的激活相关联。我们的假设是，FAM 83 B介导的PA产生导致RAF-MEK-ERK信号传导的激活和PI 3 K-AKT非依赖性mTOR信号传导的激活，这驱动了乳腺癌的发展。成功完成拟议的研究将提供有关癌细胞中FAM 83 B抑制是否会同时消除MAPK和mTOR信号传导的重要信息，从而验证FAM 83 B作为治疗干预的未来靶点。本提案的目的是（1）确定FAM 83 B参与EGFR/RAS介导的转化和效应物激活。(2)定义FAM 83 B在mTOR激活中的作用，独立于经典PI 3 K-AKT信号传导轴。(3)确定FAM 83 B表达的升高是否为癌症中过度激活MAPK和mTOR信号传导提供了替代机制。

DESCRIPTION (provided by applicant): Using human mammary epithelial cells (HMECs), we performed a forward genetic screen for alterations that contribute to malignant transformation and identified a novel oncogene, named FAM83B. The N-terminus of FAM83B encodes a PLD motif, which is both necessary and sufficient for FAM83B-mediated transformation. Elevated PLD activity contributes to tumorigenesis through the increased production of phosphatidic acid (PA), a potent second messenger involved in regulating mTOR and MAPK signaling, both of which are significantly activated in FAM83B-expressing cells. Ablation of FAM83B from tumor-derived cells with elevated EGFR or HER2, or from HMECs transformed by activated RAS, inhibited their proliferation, anchorage-independent growth and tumorigenicity, supporting a role for FAM83B as a critical EGFR/RAS- signaling intermediary. Together with the analysis of FAM83B expression in human tumor specimens, which revealed its overexpression in a variety of human cancers, our results suggest that FAM83B represents a novel oncoprotein involved in upregulating MAPK and mTOR signaling. The goals of this proposal are to define the involvement of FAM83B in MAPK and mTOR signaling, and examine human cancer specimens to correlate FAM83B expression with the activation of these highly important signaling cascades. Our hypothesis is that the FAM83B-mediated production of PA results in the activation of RAF-MEK-ERK signaling and the PI3K-AKT-independent activation of mTOR signaling, which drives breast cancer development. Successful completion of the proposed studies will provide important information regarding whether FAM83B inhibition in cancer cells will simultaneously ablate MAPK and mTOR signaling, validating FAM83B as a future target for therapeutic intervention. The aims of this proposal are to (1) Determine the involvement of FAM83B in EGFR/RAS-mediated transformation and effector activation. (2) Define the role of FAM83B in mTOR activation, independently of the canonical PI3K-AKT signaling axis. (3) Determine whether elevation of FAM83B expression provides an alternative mechanism for hyperactivating MAPK and mTOR signaling in cancer.