C5a induces A549 cell proliferation of non-small cell lung cancer via GDF15 gene activation mediated by GCN5-dependent KLF5 acetylation

Chenhui Zhao,Yongqian Shu,Fengxia He,Ling Ma,Weiming Zhang,Dan Zhao,Wen Qiu,Pei Ma,Erbao Zhang,Yingwei Wang,Fengming Yang,Zhiwei Zhang,Yongting Li,Yiqian Liu

doi:10.1038/s41388-018-0298-9

Abstract

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, and multiple evidence has confirmed that C5a production is elevated in NSCLC microenvironment. Although NSCLC cell proliferation induced by C5a has been reported, the involved mechanism has not been elucidated. In this study, we examined the proliferation-related genes (i.e., KLF5, GCN5, and GDF15) and C5a receptor (C5aR) expression in tumor tissues as well as C5a concentration in plasma of NSCLC patients, and then determined the roles of KLF5, GCN5, and GDF15 in C5a-triggered NSCLC cell proliferation and the related mechanism both in vitro and in vivo. Our results found that the expression of KLF5, GCN5, GDF15, C5aR, and C5a was significantly upregulated in NSCLC patients. Mechanistic exploration in vitro revealed that C5a could facilitate A549 cell proliferation through increasing KLF5, GCN5, and GDF15 expression. Besides, KLF5 and GCN5 could form a complex, binding to GDF15 promoter in a KLF5-dependent manner and leading to GDF15 gene transcription. More importantly, GCN5-mediated KLF5 acetylation contributing to GDF15 gene transcription and cell proliferation upon C5a stimulation, the region (−103 to +58 nt) of GDF15 promoter which KLF5 could bind to, and two new KLF5 lysine sites (K335 and K391) acetylated by GCN5 were identified for the first time. Furthermore, our experiment in vivo demonstrated that the growth of xenograft tumors in BALB/c nude mice was greatly suppressed by the silence of KLF5, GCN5, or GDF15. Collectively, these findings disclose that C5a-driven KLF5–GCN5–GDF15 axis had a critical role in NSCLC proliferation and might serve as targets for NSCLC therapy.

Highlights

Complement participates in the processes of inflammatory diseases and malignant tumors [1,2,3]
Given that the proproliferation function of kruppel-like factor 5 (KLF5), GCN5, and growth differentiation factor 15 (GDF15) has been confirmed, and the earlier stage of our study found that KLF5, GCN5, GDF15, C5a and C5a receptor (C5aR) expression increased in Non-small cell lung cancer (NSCLC) patients, how C5a triggers NSCLC cell proliferation and the expression of KLF5, GCN5, or GDF15, and what impact of KLF5, GCN5, or GDF15 on NSCLC cell proliferation in response to C5a and the corresponding mechanism need to be clarified
We analyzed the correlation between KLF5, GCN5, GDF15, or C5aR expression and clinic-pathological parameters of the 185 NSCLC patients, and found that the expression of these proteins was tightly linked with the tumor size, lymph node metastasis, and TNM stage, but not related to tumor type, patient age and sex (Supplementary Tables 3 to 6)

Summary

Introduction

Complement participates in the processes of inflammatory diseases and malignant tumors [1,2,3]. Non-small cell lung cancer (NSCLC) is the most common type of lung cancer [9]. Many researchers have uncovered that inflammatory cytokines or mediators, e.g., C5a are involved in NSCLC carcinogenesis and proliferation [10,11,12], the mechanism of C5a governing NSCLC cell proliferation remains largely unclear. It is well known that cell proliferation is associated with the upregulation of transcription factors, transcriptional coactivators and pro-proliferation molecules in response to extracellular stimuli [13, 14]. Kruppel-like factor 5 (KLF5), as a transcription factor, can boost breast cancer cell proliferation [15], and activate sox or HIF-1α transcription via binding to GC-rich DNA sequences, resulting in lung cancer proliferation [16]. Growth differentiation factor 15 (GDF15) tends to be an oncoprotein contributing to

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Conclusion