A Downmodulated MicroRNA Profiling in Patients with Gastric Cancer

Abstract

Objective. Here, we aim to investigate the microRNA (miR) profiling in human gastric cancer (GC). Methods. Tumoral and matched peritumoral gastric specimens were collected from 12 GC patients who underwent routine surgery. A high-throughput miR sequencing method was applied to detect the aberrantly expressed miRs in a subset of 6 paired samples. The stem-loop quantitative real-time polymerase chain reaction (qRT-PCR) assay was subsequently performed to confirm the sequencing results in the remaining 6 paired samples. The profiling results were also validated in vitro in three human GC cell lines (BGC-823, MGC-803, and GTL-16) and a normal gastric epithelial cell line (GES-1). Results. The miR sequencing approach detected 5 differentially expressed miRs, hsa-miR-132-3p, hsa-miR-155-5p, hsa-miR-19b-3p, hsa-miR-204-5p, and hsa-miR-30a-3p, which were significantly downmodulated between the tumoral and peritumoral GC tissues. Most of the results were further confirmed by qRT-PCR, while no change was observed for hsa-miR-30a-3p. The in vitro finding also agreed with the results of both miR sequencing and qRT-PCR for hsa-miR-204-5p, hsa-miR-155-5p, and hsa-miR-132-3p. Conclusion. Together, our findings may serve to identify new molecular alterations as well as to enrich the miR profiling in human GC.

Figure 1

Five downregulated miRs between gastric tumor (T) and peritumoral tissue (PT) were identified by the high-throughput miR sequencing method. Tag counts refers to the normalized tag number of the mature miRs annotated in miRBase 21 (TPM), including the tag number of all samples. A fold change less than 0.5 (as well as p value less than 0.05) indicated that the expression of the miR was downregulated in gastric tumor compared with the corresponding adjacent tissue. Data are represented as mean ± SD, n = 6.

Figure 2

Stem-loop qRT-PCR confirmed the altered expression pattern of four miRs between tumoral (T) and peritumoral tissues (PT) in vivo. The relative miR expression levels were normalized by RNU6B. Data are expressed as mean ± SD, n = 6. An asterisk (^∗) indicates p < 0.05.

Figure 3

The expression levels of hsa-miR-204-5p, hsa-miR-155-5p, and hsa-miR-132-3p were relatively downregulated in three human GC cell lines. The expression levels of the three GC cell lines (MGC-803, BGC-823, and GTL-16) were calculated as relative expression to that of the control group, that is, the normal gastric epithelial cell line (GES-1). Experiments were performed in triplicate. Data are expressed as mean ± SD. An asterisk (^∗) indicates p < 0.05 (versus that in GES-1).