Inactivation of ABL kinases suppresses non–small cell lung cancer metastasis
Jing Jin Gu, Clay Rouse, Xia Xu, Jun Wang, Mark W. Onaitis, Ann Marie Pendergast
Jing Jin Gu, Clay Rouse, Xia Xu, Jun Wang, Mark W. Onaitis, Ann Marie Pendergast
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Research Article Cell biology Oncology

Inactivation of ABL kinases suppresses non–small cell lung cancer metastasis

Abstract

Current therapies to treat non–small cell lung carcinoma (NSCLC) have proven ineffective owing to transient, variable, and incomplete responses. Here we show that ABL kinases, ABL1 and ABL2, promote metastasis of lung cancer cells harboring EGFR or KRAS mutations. Inactivation of ABL kinases suppresses NSCLC metastasis to brain and bone, and other organs. ABL kinases are required for expression of prometastasis genes. Notably, ABL1 and ABL2 depletion impairs extravasation of lung adenocarcinoma cells into the lung parenchyma. We found that ABL-mediated activation of the TAZ and β-catenin transcriptional coactivators is required for NSCLC metastasis. ABL kinases activate TAZ and β-catenin by decreasing their interaction with the β-TrCP ubiquitin ligase, leading to increased protein stability. High-level expression of ABL1, ABL2, and a subset of ABL-dependent TAZ- and β-catenin–target genes correlates with shortened survival of lung adenocarcinoma patients. Thus, ABL-specific allosteric inhibitors might be effective to treat metastatic lung cancer with an activated ABL pathway signature.

Authors

Jing Jin Gu, Clay Rouse, Xia Xu, Jun Wang, Mark W. Onaitis, Ann Marie Pendergast

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Figure 6

ABL kinases promote TAZ and β-catenin protein stability.

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ABL kinases promote TAZ and β-catenin protein stability. (A) PC9 cells w...
(A) PC9 cells were treated with or without GNF5 followed by addition of MG132 (10 μM for 6 hours, 1 μM for 24 hours). TAZ and β-catenin protein levels were evaluated by Western blotting. Tubulin was used as loading control. (B) PC9 parental or PC9 cells expressing active ABL1 (ABL1-PP) were treated with cycloheximide (CHX, 100 μg/ml) for the indicated times. Expression of TAZ and β-catenin proteins was analyzed by Western blotting and quantified using Fiji ImageJ software. Relative protein intensity is shown. The membrane was stripped and reprobed with anti-tubulin antibody. (C) PC9 cells were treated with or without GNF5 (left panel), or transduced with either scrambled (SCR) or ABL1/ABL2-specific (AA) shRNAs (right panel). Cell lysates were analyzed by Western blotting with antibodies specific for phosphorylated serine (S) or threonine (T) residues in β-catenin (p-β-catenin), GSK3β (p-GSK3β), and Akt (p-Akt). Tubulin was used as loading control. The same samples were run contemporaneously in several parallel gels to blot with indicated antibodies. (D) PC9 cells were treated with or without GNF5 (24 hours); β-catenin protein was immunoprecipitated (IP) followed by Western blotting with anti–β-TrCP and reprobed with anti–β-catenin antibodies. (E) PC9 cells were treated with or without GNF5 in the indicated doses (μM) for 48 hours. IP-TAZ was followed by Western blotting with anti–p-YAP (S127) for detecting p-TAZ S89 and reprobed with anti-TAZ antibody. (F) PC9 cells were treated with or without GNF5 (24 hours); IP-TAZ was followed by Western blotting with anti–β-TrCP and anti–14-3-3 antibodies and reprobed with anti-TAZ antibodies. Normal mouse IgG was used for control IPs.