ER resident protein 44 promotes malignant phenotype in nasopharyngeal carcinoma through the interaction with ATP citrate lyase

Hui Tian,Miao Gu,Si Shi,Bo You,Qicheng Zhang,Yiwen You

doi:10.1186/s12967-020-02694-1

Hui Tian, Miao Gu + Show 4 more

Open Access

https://doi.org/10.1186/s12967-020-02694-1

Copy DOI

Abstract

BackgroundNasopharyngeal carcinoma (NPC) is one of the most common malignancy in head and neck. With the development of treatments, the prognosis has improved these years, but metastasis is still the main cause of treatment failure. The endoplasmic reticulum (ER) resident protein 44 is a UPR-induced ER protein of the protein disulphide isomerase (PDI) family. This study investigated the role of ERp44 in NPC progression.MethodsFirstly, immunohistochemistry, western blot and qRT-PCR were used to investigate the expression of ERp44 in NPC samples and cell lines. We analyzed 44 NPC samples for ERp44 expression and investigated the association between its expression level with clinicopathologic parameters. Then we took CCK8, Transwell migration assay and used the zebrafish model to access the role of ERp44 on the malignant phenotype in NPC cells. Secondly, we used co-IP to gain the proteins that interact with ERp44 and took proteomic analysis. Furthermore, we successfully constructed the mutant variants of ERp44 and found the interaction domain with ATP citrate lyase(ACLY). Lastly, we subcutaneously injected NPC cells into nude mice and took immunohistochemistry to exam the expression of ACLY and ERp44. Then we used western blot to detect the expression level of epithelial-mesenchymal transition (EMT) markers.ResultsIn the present study, we found ERp44 was elevated in NPC tissues and correlated with clinical stages and survive state of the patients. In vitro, the downregulation of ERp44 in NPC cells (CNE2, 5-8F) could suppress cells proliferation and migration. After that, we recognized that ACLY might be a potential target that could interact with ERp44. We further constructed the mutant variants of ERp44 and found the interaction domain with ACLY. The promotion of ERp44 on cell migration could be inhibited when ACLY was knocked down. More importantly, we also observed that the interaction of ERp44 with ACLY, especially the thioredoxin region in ERp44 play a vital role in regulating EMT. Lastly, we found ERp44 was positively correlated with the expression of ACLY and could promote NPC cells growth in nude mice.ConclusionOur data indicated that ERp44 participates in promoting NPC progression through the interaction with ACLY and regulation of EMT.

Highlights

Nasopharyngeal carcinoma (NPC) is one of the most common malignancy in head and neck
The results showed that both the protein and mRNA levels of ERp44 were increased in most NPC tissues (Fig. 1a, b)
We found in most NPC samples, ERp44 was cytoplasmic positively staining, and more importantly, it had higher expression in NPC than normal tissues (Fig. 1c)

Summary

Introduction

Nasopharyngeal carcinoma (NPC) is one of the most common malignancy in head and neck. With the development of treatments, the prognosis has improved these years, but metastasis is still the main cause of treatment failure. According to the International Agency for Research on Cancer (IARC), more than 120,000 new cases were reported in 2018 [1]. NPC has a tendency to invade and metastasize, more than 70% of the patients were locoregionally advanced when they were newly diagnosed [3]. Though the prognosis has improved with the development of treatments, distant metastasis is still the main cause of treatment failure [4, 5]. Know more about the molecular mechanism of NPC development might help to develop novel prognostic markers and advance treatments for NPC patients

Methods

Results

Conclusion