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. 2011 Jul;2(4):613-619.
doi: 10.3892/ol.2011.313. Epub 2011 May 13.

MicroRNA profiling of gastric cancer patients from formalin-fixed paraffin-embedded samples

Soshi Osawa  1 , Yutaka Shimada, Shinichi Sekine, Tomoyuki Okumura, Takuya Nagata, Junya Fukuoka, Kazuhiro Tsukada
Affiliations

MicroRNA profiling of gastric cancer patients from formalin-fixed paraffin-embedded samples

Soshi Osawa et al. Oncol Lett. 2011 Jul.

Abstract

MicroRNA (miRNA) is a small non-coding RNA that targets specific mRNA. Recent progress in the extraction of RNA from formalin-fixed paraffin-embedded (FFPE) tissues has facilitated miRNA profiling using samples stored in laboratories worldwide. In the present study, miRNA profiling of gastric cancer patients is determined using FFPE samples. First, criteria were established for determining evaluable RNA from the FFPE samples. miRNA profiling was then undertaken using miRNA oligo chips with 885 featured genes. The FFPE samples were obtained from 47 gastric cancer patients who underwent operations between 1997 and 2007. Results showed that out of 47 paired samples, 37 pairs (78.8%) were evaluable by our criteria. A total of 30 miRNAs were significantly up-regulated and 11 miRNAs were down-regulated in gastric cancer compared with those in normal gastric tissue. Among these, 14 miRNAs, including miR-21, were identified as prognostic factors of gastric cancer patients. Furthermore, miR-34a was selected as an independent prognostic factor. In conclusion, we identified miRNAs that are associated with the prognosis of gastric cancer patients. miRNA profiling using FFPE samples is a useful and promising method of evaluation for samples stored in laboratories worldwide, and can generate extremely valuable clinical data.

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Figures

Figure 1
Figure 1
Selection of the gastric cancer patients in this study.
Figure 2
Figure 2
Method of making thin slices from a FFPE block. Tumor samples that occupy more than 70% of the slice tissue were used. T indicates the tumor in the lower figures.
Figure 3
Figure 3
Survival curves of the patients. In total, 13 over-expressed miRNAs were found to be significant prognostic factors by Kaplan-Meier estimates of overall survival (P<0.05); all cases are shown. On the other hand, miR-143 was the only significant prognostic factor exhibiting a reduced miRNA expression.
Figure 3
Figure 3
Survival curves of the patients. In total, 13 over-expressed miRNAs were found to be significant prognostic factors by Kaplan-Meier estimates of overall survival (P<0.05); all cases are shown. On the other hand, miR-143 was the only significant prognostic factor exhibiting a reduced miRNA expression.
Figure 4
Figure 4
qRT-PCR using FFPE tissues. The expression of certain miRNAs was verified in the 3 remaining FFPE specimens by qRT-PCR. miR-21 and miR106b are over-expressed in DNA chips. miR-133a, miR-133b and miR-145 exhibit a reduced expression in DNA chips.
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