FAM83B mediates EGFR- and RAS-driven oncogenic transformation
Rocky Cipriano, James Graham, Kristy L.S. Miskimen, Benjamin L. Bryson, Ronald C. Bruntz, Sarah A. Scott, H. Alex Brown, George R. Stark, Mark W. Jackson
Rocky Cipriano, James Graham, Kristy L.S. Miskimen, Benjamin L. Bryson, Ronald C. Bruntz, Sarah A. Scott, H. Alex Brown, George R. Stark, Mark W. Jackson
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Research Article

FAM83B mediates EGFR- and RAS-driven oncogenic transformation

Abstract

Aberrant regulation of growth signaling is a hallmark of cancer development that often occurs through the constitutive activation of growth factor receptors or their downstream effectors. Using validation-based insertional mutagenesis (VBIM), we identified family with sequence similarity 83, member B (FAM83B), based on its ability to substitute for RAS in the transformation of immortalized human mammary epithelial cells (HMECs). We found that FAM83B coprecipitated with a downstream effector of RAS, CRAF. Binding of FAM83B with CRAF disrupted CRAF/14-3-3 interactions and increased CRAF membrane localization, resulting in elevated MAPK and mammalian target of rapamycin (mTOR) signaling. Ablation of FAM83B inhibited the proliferation and malignant phenotype of tumor-derived cells or RAS-transformed HMECs, implicating FAM83B as a key intermediary in EGFR/RAS/MAPK signaling. Analysis of human tumor specimens revealed that FAM83B expression was significantly elevated in cancer and was associated with specific cancer subtypes, increased tumor grade, and decreased overall survival. Cumulatively, these results suggest that FAM83B is an oncogene and potentially represents a new target for therapeutic intervention.

Authors

Rocky Cipriano, James Graham, Kristy L.S. Miskimen, Benjamin L. Bryson, Ronald C. Bruntz, Sarah A. Scott, H. Alex Brown, George R. Stark, Mark W. Jackson

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Figure 6

EGFR signaling is dependent on FAM83B expression.

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EGFR signaling is dependent on FAM83B expression. (A) HME1 cells express...
(A) HME1 cells expressing GFP or FAM83B were grown in the absence of mammary epithelial growth supplement for 24 hours and then treated with 10 ng/ml EGF for 15, 30, 120, and 240 minutes. Immunoblot analysis of phospho-ERK1/2, ERK1/2, and GAPDH was performed. (B) Immunoblot analysis of phospho-ERK1/2, ERK1/2, and GAPDH was performed on extracts from MDA468 cells expressing a shRNA targeting GFP or FAM83B (shB2). MDA468 and HCC1937 cells expressing a shRNA targeting GFP or FAM83B were serum starved for 48 hours and then treated with EGF for 20 minutes. Immunoblot analysis of phospho-ERK1/2, ERK1/2, and GAPDH was performed. (C) FAM83B conferred decreased sensitivity to EGFR inhibition. HME1 cells expressing GFP or FAM83B were treated with EGFR inhibitor AG1478 at 50, 100, and 200 nM, and cell number was quantified 5 days later. (D) HME1 cells expressing GFP or FAM83B were grown as 3D cultures in lrBM in the presence and absence of AG1478 (100 and 200 nM) for 10 days. Immunoblot analysis of phospho-ERK1/2, ERK1/2, and GAPDH was performed.