Original Article
Copyright ©2014 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Dec 21, 2014; 20(47): 17883-17893
Published online Dec 21, 2014. doi: 10.3748/wjg.v20.i47.17883
Differential gene expression profiling of gastric intraepithelial neoplasia and early-stage adenocarcinoma
Xue Xu, Lin Feng, Yu Liu, Wei-Xun Zhou, Ying-Cai Ma, Gui-Jun Fei, Ning An, Yuan Li, Xi Wu, Fang Yao, Shu-Jun Cheng, Xing-Hua Lu
Xue Xu, Gui-Jun Fei, Xi Wu, Fang Yao, Xing-Hua Lu, Department of Gastroenterology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100730, China
Xue Xu, Ning An, Graduate School of Peking Union Medical College and Chinese Academy of Medical Science, Beijing 100730, China
Lin Feng, Yu Liu, Ning An, Shu-Jun Cheng, State Key Laboratory of Molecular Oncology, Cancer Institute Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100021, China
Wei-Xun Zhou, Yuan Li, Department of Pathology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100730, China
Ying-Cai Ma, Department of Gastroenterology, Qinghai Provincial People’s Hospital, Xining 810007, Qinghai Province, China
Author contributions: Xu X carried out most of the experiments and participated in drafting the manuscript; Lu XH and Cheng SJ were leaders of the project, who conceived, initiated, and designed the study; Feng L contributed to the design of all experiments and revised the manuscript; Wu X, Yao F, Lu XH, Ma YC and Fei GJ collected all the patient samples and contributed to the design of the experiments; Fei GJ and Xu X collected patient clinical data; An N and Xu X contributed to the RNA preparation; Feng L performed array hybridization with assistance from Xu X and An N; Xu X participated in the bioinformatics analyses with the guidance of Feng L and Liu Y; Xu X performed the real time qPCR and immunohistochemical staining experiments and statistical analysis with assistance from Feng L and Liu Y; Zhou WX and Li Y carried out most of the pathological diagnosis and immunohistochemical evaluation; Lu XH and Cheng SJ supervised the project; all authors read and approved the final manuscript.
Supported by The specific grants of Public-Funded Projects in the Health Industry, Grant 200902002
Correspondence to: Xing-Hua Lu, Department of Gastroenterology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Shuai Fu Yuan 1, Dongcheng District, Beijing 100730, China. lxhbj2000@aliyun.com
Telephone: +86-10-69155016 Fax: +86-10-69155016
Received: May 4, 2014
Revised: June 5, 2014
Accepted: June 14, 2014
Published online: December 21, 2014
Abstract

AIM: To investigate the differentiated whole genome expression profiling of gastric high- and low-grade intraepithelial neoplasia and early-stage adenocarcinoma.

METHODS: Gastric specimens from an upper magnifying chromoendoscopic targeted biopsy were collected from March 2010 to May 2013. Whole genome expression profiling was performed on 19 low-grade intraepithelial neoplasia (LGIN), 20 high-grade intraepithelial neoplasia (HGIN), 19 early-stage adenocarcinoma (EGC), and 19 chronic gastritis tissue samples using Agilent 4 × 44K Whole Human Genome microarrays. Differentially expressed genes between different types of lesions were identified using an unpaired t-test and corrected with the Benjamini and Hochberg false discovery rate algorithm. A gene ontology (GO) enrichment analysis was performed using the GeneSpring software GX 12.6. The differentially expressed gene was verified using a real-time TaqMan® PCR assay with independent tissue samples, including 26 LGIN, 15 HGIN, 14 EGC, and 20 chronic gastritis. The expression of G0S2 were further validated by immunohistochemical staining (IHC) in 24 LGIN, 40 HGIN, 30 EGC and 61 chronic gastritis specimens.

RESULTS: The gene expression patterns of LGIN and HGIN tissues were distinct. There were 2521 significantly differentially expressed transcripts in HGIN, with 951 upregulated and 1570 downregulated. A GO enrichment analysis demonstrated that the most striking overexpressed transcripts in HGIN compared with LGIN were in the category of metabolism, defense response, and nuclear factor κB (NF-κB) cascade. While the vast majority of transcripts had barely altered expression in HGIN and EGC tissues, only 38 transcripts were upregulated in EGC. A GO enrichment analysis revealed that the alterations of the immune response were most prominent in the progression from HGIN to EGC. It is worth noting that, compared with LGIN, 289 transcripts were expressed at higher levels both in HGIN and EGC. A characteristic gene, G0/G1 switch 2 (G0S2) was one of the 289 transcripts and related to metabolism, the immune response, and the NF-κB cascade, and its expression was validated in independent samples through real-time TaqMan® PCR and immunohistochemical staining. In real-time PCR analysis, the expression of G0S2 was elevated both in HGIN and EGC compared with that in LGIN (P < 0.01 and P < 0.001, respectively). In IHC analysis, G0S2 immunoreactivity was detected in the cytoplasmic of neoplastic cells, but was undetectable in chronic gastritis cells. The G0S2 expression in HGIN was higher than that of LGIN (P = 0.012, χ2 = 6.28) and EGC (P = 0.008, χ2 = 6.94).

CONCLUSION: A clear biological distinction between gastric high- and low-grade intraepithelial neoplasia was identified, and provides molecular evidence for clinical application.

Keywords: Gastric early-stage adenocarcinoma, High-and low-grade intraepithelial neoplasia, G0/G1 switch 2, Whole genome expression microarray, Quantitative real-time PCR, Immunohistochemical staining

Core tip: This is the first study to perform a comprehensive detection of the gene expression profiling of gastric low-grade and high-grade intraepithelial neoplasia and early-stage adenocarcinoma. This study collected precise samples and reports a clear distinction of gene expression profiles between gastric low-grade and high-grade intraepithelial neoplasia, thus providing molecular evidence for their different clinical application. The characteristic upregulated genes during gastric early carcinogenesis were involved in metabolism and the immune response and nuclear factor-κB pathway, whose expression was validated in independent samples through real-time TaqMan® polymerase chain reaction and immunohistochemical staining.