Molecular and Cellular Pathobiology Tankyrase-Binding Protein TNKS1BP1 Regulates Actin Cytoskeleton Rearrangement and Cancer Cell Invasion Tomokazu Ohishi 1,2 , Haruka Yoshida 1 , Masamichi Katori 3 , Toshiro Migita 1 , Yukiko Muramatsu 1 , Mao Miyake 1 , Yuichi Ishikawa 3 , Akio Saiura 4 , Shun-ichiro Iemura 5 , Tohru Natsume 5 , and Hiroyuki Seimiya 1 Abstract Tankyrase, a PARP that promotes telomere elongation and Wnt/b-catenin signaling, has various binding partners, suggest- ing that it has as-yet unidentified functions. Here, we report that the tankyrase-binding protein TNKS1BP1 regulates actin cytoskeleton and cancer cell invasion, which is closely associ- ated with cancer progression. TNKS1BP1 colocalized with actin filaments and negatively regulated cell invasion. In TNKS1BP1- depleted cells, actin filament dynamics, focal adhesion, and lamellipodia ruffling were increased with activation of the ROCK/LIMK/cofilin pathway. TNKS1BP1 bound the actin-capping protein CapZA2. TNKS1BP1 depletion dissociat- ed CapZA2 from the cytoskeleton, leading to cofilin phosphor- ylation and enhanced cell invasion. Tankyrase overexpression increased cofilin phosphorylation, dissociated CapZA2 from cytoskeleton, and enhanced cell invasion in a PARP activity– dependent manner. In clinical samples of pancreatic cancer, TNKS1BP1 expression was reduced in invasive regions. We propose that the tankyrase-TNKS1BP1 axis constitutes a posttrans- lational modulator of cell invasion whose aberration promotes cancer malignancy. Cancer Res; 77(9); 2328–38. Ó2017 AACR. Introduction Invasion is a dynamic process that involves migration of cells from their original location into depth of the tissue or outside to disseminate to other organs. Enhanced cell invasion is linked to cancer metastasis, the most prominent cause of the intrac- tability of the disease (1). Cell invasion essentially depends on the mechanistic motility of the cell, which is regulated by interactions and signaling from large macromolecular com- plexes called focal adhesions to the extracellular matrix (ECM). The cellular interface of focal adhesions consists of integrin-a/b heterodimers that bind ECM proteins (e.g., fibronectin, lami- nin, and vitronectin) and adaptor complexes (e.g., talin, vin- culin, and tensin) via the extracellular and intracellular domains, respectively (2). The adaptor complexes capture the retrograde flow of actin filaments (F-actin), and this interaction array of ECM, integrin, adaptors, and F-actin generates tractive force for cell motility (3). The Rho-associated protein kinases/LIM kinases/cofilin path- way (ROCK/LIMK/cofilin pathway) and CapZ-mediated regu- lation of actin filament dynamics play key roles in the actin/ cytoskeleton network rearrangement (4, 5). ROCKs are serine/ threonine kinases that promote actin organization through phosphorylating several downstream targets, including LIMKs (6). Phosphorylated LIMKs then phosphorylate actin-depoly- merizing factor/cofilin on serine 3. While cofilin facilitates actin depolymerization, phosphorylation of cofilin on serine 3 (p-cofilin) attenuates its actin depolymerization activity and causes increased numbers of focal adhesion complexes, actin stress fiber formation, and enhanced cell motility (7, 8). Aberrant promotion of LIMK signaling (e.g., by increased expression of the upstream regulators RhoA and ROCK) is observed in many cancers and is associated with cancer metas- tasis (9, 10). Therefore, LIMK inhibitors, which inhibit gener- ation of p-cofilin, are thought to be promising anti-invasive agents (11). Tankyrase is a member of the PARP family that catalyzes formation of long PAR chains onto acceptor proteins using NAD þ (12). PARylation confers a drastic negative charge to the acceptor proteins and modulates their functions (13). Tankyrase PARylates the telomeric protein TRF1, which is a negative regulator of telomere elongation (12). PARylated TRF1 dissociates from telomeres and is degraded by the ubiquitin/proteasome system. The resulting telomeres exhibit an "open" state that allows easier access of telomerase, which in turn elongates telomeres (14, 15). 1 Division of Molecular Biotherapy, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Koto-ku, Tokyo, Japan. 2 Institute of Microbial Chemistry (BIKAKEN), Numazu, Numazu-shi, Shizuoka, Japan. 3 Divison of Pathology, Cancer Institute, Japanese Foundation for Cancer Research, Koto- ku, Tokyo, Japan. 4 Department of Gastroenterological Surgery, Cancer Institute Hospital, Japanese Foundation for Cancer Research, Koto-ku, Tokyo, Japan. 5 Molecular Profiling Research Center for Drug Discovery, National Institute of Advanced Industrial Science and Technology, Koto-ku, Tokyo, Japan. Note: Supplementary data for this article are available at Cancer Research Online (http://cancerres.aacrjournals.org/). Current address for M. Katori: Musashimurayama Hospital, 1-1-5 Enoki, Musa- shimurayama, Tokyo 208-0022, Japan; and current address for S.-i. Iemura: Translational Research Center, Fukushima Medical University, 11-25 Sakaemachi, Fukushima City, Fukushima 960-8031, Japan. Corresponding Author: Hiroyuki Seimiya, Division of Molecular Biotherapy, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan. Phone: 81-3-3570-0466; Fax: 81-3-3570-0484; E-mail: hseimiya@jfcr.or.jp doi: 10.1158/0008-5472.CAN-16-1846 Ó2017 American Association for Cancer Research. Cancer Research Cancer Res; 77(9) May 1, 2017 2328 on June 18, 2020. © 2017 American Association for Cancer Research. cancerres.aacrjournals.org Downloaded from Published OnlineFirst February 15, 2017; DOI: 10.1158/0008-5472.CAN-16-1846