Elevated expression of mature miR-21 and miR-155 in cancerous gastric tissues from Chinese patients with gastric cancer

Abstract

Objective: MicroRNA (miRNA) expression is deregulated in many types of human cancers. We sought to investigate the expression patterns of the miRNAs, miR-21, miR-145 and miR-155 in sporadic gastric cancer in a Chinese population.

Methods: Total RNA was extracted from archived gastric cancer tissues and adjacent non-cancerous tissues from 20 pairs of paraffin-embedded specimens. Expression levels of miR-21, miR-145 and miR-155 were detected by quantitative reverse transcriptase PCR using a specific stem-loop primer, with U6 as the internal reference gene.

Results: The expression of miR-21 and miR-155 in gastric cancer samples was significantly higher than in paired non-cancerous samples (P < 0.05). There was no statistically significant difference in expression levels of miR-145 between cancerous and non-cancerous tissues (P > 0.05).

Conclusion: In Chinese sporadic gastric cancer tissues, the expressions of the oncogenic miR-21 and miR-155 were significantly up-regulated, while the expression of the tumor suppressor miR-145 was decreased, although this decrease was not statistically significant. Thus there is specificity in the miRNA expression pattern in gastric cancers in the Chinese population.

Keywords: MicroRNA; expression; gastric cancer.

Fig. 1. Ct values of miR-21, -145 and -155 in human gastric tumor tissue (TT) and adjacent non-tumor tissue (NTT) by qRT-PCR.

Expression of miR-21, -145 and -155 in human gastric cancer FFPE tissues were examined by qRT-PCR using real-time PCR. Twenty cases of gastric cancers were examined. The paired samples from tumor tissue and the adjacent non-tumor tissue in the same patient were examined. A0: miR-21 in NTT; A1: miR-21 in TT; B0: miR-145 in NTT; B1: miR-145 in TT; C0: miR-153 in NTT; C1: miR-153 in TT.

Fig. 2. Value of ΔCt and the respective 2^−ΔCt of miR-21 in gastric tumor tissue (TT) and non-tumor tissue (NTT).

The ΔCt range was from -6.318 to -1.707 and the 2^−ΔCt range was from 3.265 to 79.804 in non-tumor tissues, while the ΔCt range was from -7.900 to -1.814 and 2^−ΔCt range was from 3.517 to 238.870 in cancerous tissues.

Fig. 3. Value of ΔCt and the respective 2^−ΔCt of miR-145 in gastric tumor tissue (TT) and non-tumor tissue (NTT).

The ΔCt range was from -5.761 to 1.897 and the 2^−ΔCt range was from 0.269 to 54.213 in non-tumor tissues. The ΔCt range was from -5.045 to 0.987 and the 2^−ΔCt range was from 0.504 to 33.023 in cancerous tissues.

Fig. 4. Value of ΔCt and the respective 2^−ΔCt of miR-155 in gastric tumor tissue (TT) and non-tumor tissue (NTT).

The ΔCt range was from 0.768 to 7.241 and the 2^−ΔCt range was from 0.007 to 0.587 in non-tumor tissues. The ΔCt range was from -1.857 to 4.300 and the 2^−ΔCt range was from 0.051 to 3.624 in cancerous tissues.

Fig. 5. Fold changes of the expression of the three miRNAs.

The mean RQ of miR-21 was 5.161±6.908; The mean RQ of miR-145 was 3.014±7.719; The mean RQ of miR-155 was 4.696±5.690. The correlation between RQ of miR-21 and RQ of miR-145: P = 0.013, r = 0.558 (Spearman Rank test, 2-tailed); The correlation between RQ of miR-21 and RQ of miR-155: P = 0.000, r = 0.904 (Pearson test, 2-tailed); The correlation between RQ of miR-145 and RQ of miR-155: P = 0.110, r = 0.368 (Spearman Rank test, 2-tailed).