Identification of a noval oncogene using validation-based insertional mutagenesis

描述(申请人提供)：使用人乳腺上皮细胞(HMECs)，我们进行了有助于恶性转化的改变的正向遗传筛查，并确定了一个新的癌基因，命名为FAM83B。FAM83B的N端编码一个PLD基序，这是FAM83B介导的转化的必要条件和充分条件。PLD活性的升高通过增加磷脂酸(PA)的产生而促进肿瘤的发生，PA是一种强大的第二信使，参与调节mTOR和MAPK信号，这两种信号在表达FAM83B的细胞中都显著激活。从EGFR或HER2升高的肿瘤来源的细胞或激活的RAS转化的HMECs中去除FAM83B，可以抑制其增殖、锚定非依赖性生长和致瘤性，支持FAM83B作为关键的EGFR/RAS信号中介的作用。结合对FAM83B在人类肿瘤标本中表达的分析，我们的结果表明，FAM83B是一种新的癌蛋白，参与上调MAPK和mTOR信号。这项建议的目标是确定FAM83B参与MAPK和mTOR信号转导，并检查人类癌症标本以将FAM83B表达与这些高度重要的信号级联反应的激活相关联。我们的假设是，FAM83B介导的PA的产生导致RAF-MEK-ERK信号的激活和PI3K-AKT非依赖的mTOR信号的激活，从而推动乳腺癌的发展。这项拟议研究的成功完成将提供重要信息，说明在癌细胞中抑制FAM83B是否会同时消除MAPK和mTOR信号，从而验证FAM83B作为未来治疗干预的目标。本研究的目的是(1)确定FAM83B在EGFR/RAS介导的转化和效应器激活中的作用。(2)明确FAM83B在mTOR激活中的作用，独立于典型的PI3K-AKT信号轴。(3)确定FAM83B表达上调是否为肿瘤中MAPK和mTOR信号的高激活提供了一种替代机制。 公共卫生相关性：成功鉴定参与HMEC转化的新蛋白，如FAM83B，对于扩大我们对癌基因信号相互作用的理解至关重要，这些信号相互作用参与了驱动乳腺上皮细胞增生的过程。新的蛋白质还为药物开发提供了机会，这将扩大根除癌症和延长患者生命所需的治疗方法的武器库。

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. PUBLIC HEALTH RELEVANCE: Successful identification of novel proteins involved in HMEC transformation, such as FAM83B, is critical to expanding our understanding of the oncogene signaling interactions involved in driving breast epithelial hyperplasia. Novel proteins also provide opportunities for drug development that will expand the arsenal of therapies necessary for eradicating cancer and extending the life of patients.