A critical role of integrin-linked kinase, ch-TOG and TACC3 in centrosome clustering in cancer cells

Abstract

Many cancer cells contain more than two centrosomes, which imposes a potential for multipolar mitoses, leading to cell death. To circumvent this, cancer cells develop mechanisms to cluster supernumerary centrosomes to form bipolar spindles, enabling successful mitosis. Disruption of centrosome clustering thus provides a selective means of killing supernumerary centrosome-harboring cancer cells. Although the mechanisms of centrosome clustering are poorly understood, recent genetic analyses have identified requirements for both actin and tubulin regulating proteins. In this study, we demonstrate that the integrin-linked kinase (ILK), a protein critically involved in actin and mitotic microtubule organization, is required for centrosome clustering. Inhibition of ILK expression or activity inhibits centrosome clustering in several breast and prostate cancer cell lines that have centrosome amplification. Furthermore, cancer cells with supernumerary centrosomes are significantly more sensitive to ILK inhibition than cells with two centrosomes, demonstrating that inhibiting ILK offers a selective means of targeting cancer cells. Live cell analysis shows ILK perturbation leads cancer cells to undergo multipolar anaphases, mitotic arrest and cell death in mitosis. We also show that ILK performs its centrosome clustering activity in a focal adhesion-independent, but centrosome-dependent, manner through the microtubule regulating proteins TACC3 and ch-TOG. In addition, we identify a specific TACC3 phosphorylation site that is required for centrosome clustering and demonstrate that ILK regulates this phosphorylation in an Aurora-A-dependent manner.

Integrin signalling adaptors: not only figurants in the cancer story

“…Indeed inhibition of either ILK expression or its activity results in decreased cell migration and invasion, metastasis formation, induction of apoptosis in vitro 30,129,130 and in vivo [131][132][133] . In addition, on the basis of the new role of ILK in mitosis 103,104 , the potential targeting of ILK as an anti-mitotic chemotherapeutic might provide a promising alternative to the chemotherapeutics avoiding severe toxic side effects and drug resistance.…”

Let's huddle to prevent a muddle: centrosome declustering as an attractive anticancer strategy

“…6 Furthermore, various cell polarity and adhesion proteins are required for clustering in partnership with actin. 6,92 As the spotlight now focuses on the action at the cell cortex, an exciting domain for future research would be to further tease out the interplay between the actin cytoskeleton on the one hand and focal adhesion components, cell polarity proteins, cortical landmarks, and force generators on the other. Such studies will better define how these molecular players coordinately shape the forces exerted on centrosomes.…”

“…119 In breast cancer cell lines that exhibit centrosome amplification, ILK inhibition suppresses clustering via a mechanism that is independent of its role in focal adhesions, but rather requires TACC3 and ch-TOG. 92 The Drosophila TACC3 homolog, D-TACC, is also necessary for clustering in S2 cells. 6 D-TACC associates with and stabilizes both the plus-and minus-ends of astral and spindle microtubules.…”

“…121 TACC3 and ch-TOG are required for clustering in human breast BT549 and prostate cancer PC3 cells. 92 Additional work is required to elucidate the details of how the ILK-TACC3-ch-TOG triad cross-talks with other components of the clustering machinery in space and time.…”

Integrin-linked kinase: Not so ‘pseudo’ after all

“…These include b1-integrin (Hannigan et al, 1996), myelin basic protein (Hannigan et al, 1996); b-parvin (Yamaji et al, 2001); glycogen synthase kinase-3b (GSK-3b) (Delcommenne et al, 1998); Akt (Persad et al, 2001); the regulatory light chain of myosin-II, MLC-20 ; the protein phosphatase-inhibitory proteins CPI-17, PHI-1 and KEPI (Erd + odi et al, 2003); the myosin-targeting subunit of the myosin (Attwell et al, 2003) Lactation, mammary differentiation (Akhtar et al, 2009) Smooth-muscle contraction; MLC-20 phosphorylation Eto, 2009) Mitotic spindle organization (Fielding et al, , 2011) Renal agenesis (Lange et al, 2009) Akt Ser473 phosphorylation, cell survival (Persad et al, 2000(Persad et al, , 2001) Zebrafish muscle fiber-ECM adhesion (Postel et al, 2008) Human cardiomyopathy (Knoll et al, 2007) (Zervas et al, 2001) Inhibition of growth, and apoptosis of anaplastic thyroid cancer cells (Younes et al, 2005) Pancreatic cancer xenograft apoptosis (Yau et al, 2005) Mammary tumor growth (White et al, 2001) Abbreviation: ILK, integrin-linked kinase. Evidence for kinase dependence is based on effects of point mutations predicted or shown to affect catalytic function, or inhibition by the QLT class of inhibitor, with or without corroborating genetic knockout/knockdown data.…”