C5a receptor (CD88) promotes motility and invasiveness of gastric cancer by activating RhoA

// Takayoshi Kaida 1 , Hidetoshi Nitta 1 , Yuki Kitano 1 , Kensuke Yamamura 1 , Kota Arima 1 , Daisuke Izumi 1 , Takaaki Higashi 1 , Junji Kurashige 1 , Katsunori Imai 1 , Hiromitsu Hayashi 1 , Masaaki Iwatsuki 1 , Takatsugu Ishimoto 1 , Daisuke Hashimoto 1 , Yoichi Yamashita 1 , Akira Chikamoto 1 , Takahisa Imanura 2 , Takatoshi Ishiko 1 , Toru Beppu 1 , Hideo Baba 1 1 Department of Gastroenterological Surgery, Graduate School of Life Sciences, Kumamoto University, Kumamoto, Japan 2 Department of Molecular Pathology, Graduate School of Life Sciences, Kumamoto University, Kumamoto, Japan Correspondence to: Hideo Baba, email: hdobaba@kumamoto-u.ac.jp Keywords: C5a receptor, CD88, RhoA, gastric cancer Abbreviations: C5aR, C5a receptor; GC, Gastric cancer; rC5a, recombinant human complement component C5a; GDP, guanosine diphosphate; GTP, guanosine triphosphate Received: March 14, 2016     Accepted: October 01, 2016     Published: October 14, 2016 ABSTRACT Purpose: Anaphylatoxin C5a is a strong chemoattractant of the complement system that binds the C5a receptor (C5aR). The expression of C5aR is associated with poor prognosis in several cancers. However, the role of C5aR in gastric cancer (GC) is unknown. The aim of this study was to examine the role of C5aR on GC cell motility and invasion. Experimental Design: The mechanism of invasion via C5aR was assessed by analyzing cytoskeletal rearrangement and RhoA activity after C5a treatment. Moreover, we investigated the relationship between C5aR expression and the prognosis of GC patients. Results: Two human GC cell lines (MKN1 and MKN7) had high C5aR expression. An invasion assay revealed that C5a stimulation promoted the invasive ability of MKN1 and MKN7 cells and that this was suppressed by knockdown of C5aR using siRNA or a C5aR-antagonist. Moreover, overexpression of C5aR in GC cells enhanced the conversion of RhoA-guanosine diphosphate (RhoA-GDP) to RhoA-guanosine triphosphate (RhoA-GTP) after C5a stimulation and caused morphological changes, including increased expression of stress fibers and filopodia. Examination of tumor specimens from 100 patients with GC revealed that high C5aR expression (35 of 100 samples, 35.0%) was associated with increased invasion depth, vascular invasion and advanced stage. The 5-year overall survival of patients with high or low C5aR expression was 58.2% and 68.5%, respectively (p=0.008). Conclusions: This study is the first to demonstrate that C5aR promotes GC cell invasion by activating RhoA and is associated with a poor prognosis in GC patients. Therefore, this study provides a biomarker for GC patients who require an advanced therapeutic strategy.