Metastasis-associated PRL-3 induces EGFR activation and addiction in cancer cells
Abdul Qader Omer Al-aidaroos, … , Wee Joo Chng, Qi Zeng
Abdul Qader Omer Al-aidaroos, … , Wee Joo Chng, Qi Zeng
Published July 8, 2013
Citation Information: J Clin Invest. 2013;123(8):3459-3471. https://doi.org/10.1172/JCI66824.
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Research Article Oncology

Metastasis-associated PRL-3 induces EGFR activation and addiction in cancer cells

Abstract

Metastasis-associated phosphatase of regenerating liver-3 (PRL-3) has pleiotropic effects in driving cancer progression, yet the signaling mechanisms of PRL-3 are still not fully understood. Here, we provide evidence for PRL-3–induced hyperactivation of EGFR and its downstream signaling cascades in multiple human cancer cell lines. Mechanistically, PRL-3–induced activation of EGFR was attributed primarily to transcriptional downregulation of protein tyrosine phosphatase 1B (PTP1B), an inhibitory phosphatase for EGFR. Functionally, PRL-3–induced hyperactivation of EGFR correlated with increased cell growth, promigratory characteristics, and tumorigenicity. Moreover, PRL-3 induced cellular addiction to EGFR signaling, as evidenced by the pronounced reversion of these oncogenic attributes upon EGFR-specific inhibition. Of clinical significance, we verified elevated PRL-3 expression as a predictive marker for favorable therapeutic response in a heterogeneous colorectal cancer (CRC) patient cohort treated with the clinically approved anti-EGFR antibody cetuximab. The identification of PRL-3–driven EGFR hyperactivation and consequential addiction to EGFR signaling opens new avenues for inhibiting PRL-3–driven cancer progression. We propose that elevated PRL-3 expression is an important clinical predictive biomarker for favorable anti-EGFR cancer therapy.

Authors

Abdul Qader Omer Al-aidaroos, Hiu Fung Yuen, Ke Guo, Shu Dong Zhang, Tae-Hoon Chung, Wee Joo Chng, Qi Zeng

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Figure 1

PRL-3 overexpression activates the EGFR in A431 cells.

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PRL-3 overexpression activates the EGFR in A431 cells. (A) Representativ...
(A) Representative immunoblots of total lysates from serum-starved A431-vec and A431-PRL-3 cells with or without EGF (100 ng/ml; 20 minutes) stimulation. The anti–p-Tyr blot was stripped and reprobed with an anti-GFP antibody. Arrow identifies a PRL-3–induced, EGF-responsive tyrosine phosphorylated 165-kDa protein. (B) Total protein lysates from A431-vec (left panel) or A431-PRL-3 (right panel) cells were analyzed using an antibody array against 71 unique PTKs (array map provided in Supplemental Figure 1). The top 3 “PRL-3–activated” or “PRL-3–inactivated” PTKs are indicated on the right, with spot IDs and gene names. (C) Arrays in B were analyzed using densitometry, and fold changes in individual spots were calculated after normalizing to the positive controls on each membrane (mean ± standard deviation, n = 2). Gene names and fold changes (PRL-3 versus vec) of the top 3 “PRL-3–activated” or “PRL-3–inactivated” PTKs are highlighted. (D) A431-vec or A431-PRL-3 lysates were immunoblotted with antibodies against phosphorylated EGFR (Y1068) and reprobed for total EGFR. GAPDH was used as a loading control. (E) After treatment as in A, lysates from A431-vec and A431-PRL-3 cells were immunoprecipitated (IP) with an anti-EGFR antibody and immunoblotted (IB) with anti-EGFR and anti-GRB2 antibodies. Lane pairs were run on the same gel but were noncontiguous. TCL, total cell lysate. (F) Various EGFR downstream signaling components were analyzed in A431-vec and A431-PRL-3 cells. GAB1 was immunoprecipitated and analyzed using a phosphotyrosine antibody. Blots were probed with the various antibodies as indicated. GAPDH was used as a loading control.