CCDC88A, a prognostic factor for human pancreatic cancers, promotes the motility and invasiveness of pancreatic cancer cells.

Aki Tanouchi,Kazuhiro Hanazaki,Seiji Naganuma,Motoaki Saito,Mutsuo Furihata,Toshiji Saibara,Ken Dabanaka,Masashi Kimura,Keisuke Taniuchi,Takahiro Shimizu,Takuhiro Kohsaki,Ryohei Watanabe

doi:10.1186/s13046-016-0466-0

Abstract

BackgroundCoiled-Coil Domain Containing 88A (CCDC88A) was identified as a substrate of the serine/threonine kinase Akt that is capable of binding to the actin cytoskeleton. The aim of this study was to investigate the potential role of CCDC88A in the migration and invasiveness of pancreatic ductal adenocarcinoma (PDAC) cells.MethodsImmunohistochemistry was performed to determine whether high CCDC88A expression in human PDAC tissues is correlated with poor prognosis. Immunoprecipitation, immunoblotting and immunocytochemistry were performed to determine the intracellular distribution of CCDC88A, and its association with the serine/threonine kinase Akt and actin-filaments in PDAC cells. Phosphoprotein array analysis was performed to determine CCDC88A-associated intracellular signaling pathways. Finally, immunofluorescence analyses and Matrigel invasion assays were performed to examine the effects of CCDC88A on the formation of cell protrusions and PDAC cell invasion.ResultsExpression of CCDC88A in PDAC tissue was significantly correlated with overall survival. CCDC88A was co-localized with peripheral actin structures in cell protrusions of migrating PDAC cells. Knockdown of CCDC88A inhibited the migration and invasiveness of PDAC cells through a decrease in cell protrusions. Although CCDC88A has been previously reported to be a binding partner and substrate of Akt, the level of active Akt was not associated with the translocation of CCDC88A towards cell protrusions. CCDC88A-dependent promotion of cell migration and invasiveness was not modulated by Akt signaling. Knockdown of CCDC88A decreased phosphorylated Src and ERK1/2 and increased phosphorylated AMPK1 in PDAC cells. Knockdown of AMPK1 inhibited the migration and invasiveness of PDAC cells. The combined data suggest that CCDC88A may be a useful marker for predicting the outcome of patients with PDAC and that CCDC88A can promote PDAC cell migration and invasion through a signaling pathway that involves phosphorylation of Src and ERK1/2 and/or dephosphorylation of AMPK1.ConclusionsCCDC88A was accumulated in cell protrusions, contributed to the formation of membrane protrusions, and increased the migration and invasiveness of PDAC cells.Electronic supplementary materialThe online version of this article (doi:10.1186/s13046-016-0466-0) contains supplementary material, which is available to authorized users.

Highlights

Coiled-Coil Domain Containing 88A (CCDC88A) was identified as a substrate of the serine/threonine kinase Akt that is capable of binding to the actin cytoskeleton
To determine whether CCDC88A expression might play a crucial role in the outcome of pancreatic ductal adenocarcinoma (PDAC) through modulation of the migration and invasiveness of cancer cells, or through its association with Akt, we evaluated the role of CCDC88A in the control of PDAC cell migration and invasion
Immunofluorescence analysis showed that CCDC88A was associated with peripheral actin structures in cell protrusions of fibronectin-stimulated S2-013 cells (Fig. 4b). These results suggested that CCDC88A is an actin-binding protein that is present in cell protrusions of PDAC cells

Summary

Introduction

Coiled-Coil Domain Containing 88A (CCDC88A) was identified as a substrate of the serine/threonine kinase Akt that is capable of binding to the actin cytoskeleton. Coiled-Coil Domain Containing 88A (CCDC88A), termed Girdin, was identified as a novel substrate of the serine/threonine kinase Akt ( called protein kinase B) that is capable of binding to the actin cytoskeleton [1]. Upon stimulation of cells with various types of growth factors, Akt phosphorylates CCDC88A at Ser-1416 in the COOH terminal domain, which plays an important role in remodeling of the actin cytoskeleton during cell migration in fibroblasts [1] and in colorectal cancer [5]. CCDC88A is phosphorylated by active Akt following stimulation of breast cancer cells with insulinlike growth factor (IGF-I), and this phosphorylation plays an important role in IGF-I-dependent cell movement [7]. CCDC88A serves as a mediator of the GPCR-Akt signaling pathway

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