Somatic mutation in the ACK1 ubiquitin association domain enhances oncogenic signaling through EGFR regulation in renal cancer derived cells

Chua, Boon Tin; Lim, Shu Jing; Tham, Su Chin; Poh, Wei Jie; Ullrich, Axel

doi:10.1016/j.molonc.2010.03.001

« Previous Next »Molecular Oncology
Volume 4, Issue 4 , Pages 323-334, August 2010

Somatic mutation in the ACK1 ubiquitin association domain enhances oncogenic signaling through EGFR regulation in renal cancer derived cells

Boon Tin Chua
- Singapore OncoGenome Project, Institute of Medical Biology, A* STAR, 8A Biomedical Grove, #06-06 Immunos, Singapore 138648, Singapore
- Corresponding author. Tel.: +65 64070270; fax: +65 64642049.
Shu Jing Lim
- Singapore OncoGenome Project, Institute of Medical Biology, A* STAR, 8A Biomedical Grove, #06-06 Immunos, Singapore 138648, Singapore
Su Chin Tham
- Singapore OncoGenome Project, Institute of Medical Biology, A* STAR, 8A Biomedical Grove, #06-06 Immunos, Singapore 138648, Singapore
Wei Jie Poh
- Singapore OncoGenome Project, Institute of Medical Biology, A* STAR, 8A Biomedical Grove, #06-06 Immunos, Singapore 138648, Singapore
Axel Ullrich
- Singapore OncoGenome Project, Institute of Medical Biology, A* STAR, 8A Biomedical Grove, #06-06 Immunos, Singapore 138648, Singapore
- Max-Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany

Received 10 February 2010; received in revised form 3 March 2010; accepted 3 March 2010. published online 22 March 2010.

Abstract

Activated Cdc42-associated Kinase, ACK1, is a non-receptor tyrosine kinase with numerous interacting partners, including Cdc42 and EGFR. Gene amplification and overexpression of ACK1 were found in many cancer types such as those of the lung and prostate. Previously, we identified both somatic- and germ line missense mutations in the ACK1 coding sequence, by surveying 261 cancer cell lines and 15 control tissues. Here, we verified and characterized the non-synonymous mutation, ACK-S985 N, located in the ubiquitin association domain of the protein.

Both overexpression and silencing experiments in MCF7 and A498 cells, respectively, demonstrated a role of the ACK1 S985 N mutation in enhancing cell proliferation, migration and anchorage-independent growth as well as the epithelial–mesenchymal transition. Further, we showed that the ACK1 S985 N mutant is unable to bind ubiquitin, unlike the wild type kinase. This contributed to ACK1 protein stability and stabilized EGFR after EGF stimulation, thereby prolonging mitogenic signaling in cancer cells. In addition, the ACK1 S985 N-EGFR interaction is enhanced, but not the ubiquitination of the receptor. Intriguingly, silencing of ACK1 in A498 cells sensitized the renal carcinoma cells to gefitinib, against which they are otherwise resistant.

The work demonstrates that other than gene amplification, a single somatic mutation in ACK1 can result in extended protein stability enabling the oncoprotein to exert its oncogenic function in tumor progression. It also provides a rationale to target ACK1 in combination with other chemotherapeutic drugs, such as EGFR inhibitors, to potentiate therapeutic action against resistant tumors.

Keywords: ACK1, Somatic mutation, Stability, EGFR, EMT, Gefitinib

Abbreviations: ACK1, activated Cdc42-associated kinase 1, UBA, Ubiquitin association domain, EGFR, epidermal growth factor receptor, RCC, renal clear cell carcinoma, EMT, epithelial–mesenchymal transition, TNF, tumor necrosis factor, HSP60, heat shock protein 60