CircRNA microarray profiling identifies a novel circulating biomarker for detection of gastric cancer

Abstract

CircRNA expression profiles for gastric cancer (GC) were screened using plasma samples from 10 GC patients with different TNM stages and 5 healthy individuals as controls. Results showed lower expression of circ-KIAA1244 in GC tissues, plasmas, and cells compare to normal controls. Further clinical data analysis demonstrated that a decreased expression of circ-KIAA1244 in plasmas was negatively correlated with TNM stage and lymphatic metastasis, and a shorter overall survival time of GC patients. Moreover, we found that circ-KIAA1244 could be detected in GC plasma exosomes and showed no obvious significance compared to the expression level in the corresponding plasmas. This study revealed a GC-tissues-derived circ-KIAA1244 could serve a novel circulating biomarker for detection of GC.

Keywords: Biomarker; Exosomes; Microarray; Plasma; circRNAs.

Fig. 1

Profiling of circular RNAs in the plasmas from GC patients with early TNM stages and normal controls. (a) Heat map shows the up-regulated and down-regulated circRNAs in case1 vs control group. (G for GC, and N for normal individuals’ plasma). Each column represents the expression profile of a tissue sample, and each row corresponds to a circRNA. High expression level is indicated by “red” and lower levels by “green”. (b) Volcano plot shows the up-regulated and down-regulated circRNAs in case1 vs control group. Higher expression levels are indicated by “red”, lower expression levels are indicated by “green”, and no significant difference is indicated by “black”. (c) KEGG analysis of circRNAs in case1 vs control group. (d) GO analysis of circRNAs in case1 vs control group. (e) Disease pathway analysis of circRNAs in case1 vs control group

Fig. 2

The biological structure of circ-KIAA1244. (a) Schematics showed that circ-KIAA1244 is derived from KIAA1244 exons 3–8. The amplification products were inserted into a T-vector for Sanger sequencing to determine their full-length. (b) qRT-PCR for the abundance of circ-KIAA1244 and KIAA1244 mRNA in GC cells treated with RNase R. (c) qRT-PCR for the abundance of circ-KIAA1244and KIAA1244 mRNA in GC cells treated with actinomycin D. (d) circ-KIAA1244 was mainly localized in the cytoplasm. (e) circ-KIAA1244 was enriched in Ago2-containing immunoprecipitates compared with control immunoglobulin G (IgG) immunoprecipitates. (f) The possible binding miRNAs and mRNAs of circ-KIAA1244. **P<0.01

Fig. 3

The expressions of circ-KIAA1244 GC samples and clinical information analysis. (a) circ-KIAA1244 expression was down-regulated in GC tissues and plasmas compared to normal controls. The correlation of their -ΔCt value was determined. N indicates normal and T indicates tumor. (b) The expression of circ-KIAA1244 in GC cell lines was lower than that in GES-1 significantly. (c) The area under the ROC curve (AUC) in distinguishing GC plasmas and normal ones was 0.7481. (d) Kaplan-Meier overall survival curve revealed patients with lower circ-KIAA1244 expression showed a reduced survival time. (e) There was no significant difference between the expression of circ-KIAA1244 in plasmas and corresponding plasma exosomes. (f) Theoretical model diagram of circ-KIAA1244 in GC: we proposed that GC-tissues-derived circ-KIAA1244 might be transmitted to plasmas via exosomes delivery and could serve as a biomarker in GC.*P<0.05, **P<0.01, ***P<0.001