BACKGROUND: We examined plasma microRNA (miRNA) concentrations from patients with gastric cancers (GCs) to assess their clinical application for diagnosing and monitoring diseases. METHODS: We initially investigated the appropriateness of plasma miRNA assay, and then compared plasma miRNA results with the expressions in cancer tissues from eight GC patients, and also compared plasma miRNAs between pre-and post-operative paired samples from 10 GC patients. Then, plasma miRNAs (miR-17-5p, miR-21, miR-106a, miR-106b and let-7a) were analysed in 69 GC patients and 30 healthy volunteers in total. RESULTS: The initial analysis showed that miRNAs were stable and detectable in all plasma samples, and the plasma miRNA levels reflected the tumour miRNAs in most cases. The levels of these miRNAs were significantly reduced in post-operative samples. In large-scale analysis, the plasma concentrations of miRNAs (miR-17-5p, miR-21, miR-106a, miR-106b) were significantly higher in GC patients than controls (P ¼ 0.05, 0.006, 0.008 and o0.001 respectively), whereas let-7a was lower in GC patients (P ¼ 0.002). The values of the area under the receiver-operating characteristic curve were 0.721 for the miR-106b assay and 0.879 for the miR-106a/ let-7a ratio assay. CONCLUSION: Detection of circulating miRNAs might provide new complementary tumour markers for GC.

Background:Several recent studies demonstrated that microRNAs (miRNAs) are stably detectable in plasma/serum. We hypothesised that plasma miRNAs concentrations contributed to potential biomarkers in patients with oesophageal squamous cell carcinoma (ESCC).Methods:We selected three oncogenic miRNAs (miR-21, miR-184, miR-221) and one tumour suppressive miRNA (miR-375), which are frequently reported in squamous cell carcinoma, as candidate targets for this plasma miRNA assay. This study was divided into three steps: (1) Determination of appropriate plasma miRNAs in preliminary tests. (2) Evaluation of whether the plasma miRNA assays could monitor tumour dynamics. (3) Validation study on the clinical application of plasma miRNA assays in 50 ESCC patients and 20 healthy volunteers.Results:(1) In preliminary tests, the plasma level of miR-21 was significantly higher (P=0.0218) and that of miR-375 (P=0.0052) was significantly lower in ESCC patients than controls. (2) The high plasma miR-21 levels reflected tumour levels in all cases (100%). The plasma level of miR-21 was significantly reduced in postoperative samples (P=0.0058). (3) On validation analysis, the plasma level of miR-21 tended to be higher in ESCC patients (P=0.0649), while that of miR-375 was significantly lower (P<0.0001) and the miR-21/miR-375 ratio was significantly higher (P<0.0001) in ESCC patients than in controls. The value of the area under the receiver-operating characteristic curve (AUC) was 0.816 for the miR-21/miR-375 ratio assay. Patients with a high plasma level of miR-21 tended to have greater vascular invasion (P=0.1554) and to show a high correlation with recurrence (P=0.0164).Conclusion:Detection of circulating miRNAs might provide new complementary tumour markers for ESCC.

Background:Several recent studies have demonstrated that microRNAs (miRNAs) are stably detectable in plasma/serum. We tested miR-221 and miR-375, which are frequently reported to be highly and poorly expressed in pancreatic cancer (PCa), as candidates for plasma biomarkers in PCa.Methods:This study was divided into three parts: (1) Confirmation of higher miR-221 levels in primary PCa tissue and cell lines than normal pancreatic tissues. (2) Evaluation of plasma miR-221 and miR-375 concentrations by comparing results from 47 consecutive PCa patients and 30 healthy volunteers. (3) Evaluation of the assay for monitoring tumour dynamics in PCa patients.Results:(1) Expression of miR-221 was significantly higher in PCa tissues and cell lines than normal pancreatic tissues. (2) Plasma miR-221 concentrations were significantly higher in PCa patients than that in benign pancreatic tumours (P=0.016) and controls (P<0.0005), while plasma miR-375 concentrations tended to be lower in PCa patients (P=0.064), and the miR-221/miR-375 ratio was significantly higher (P<0.0001) in PCa patients than in controls. (3) Plasma miR-221 concentrations were significantly reduced in postoperative samples (P=0.018). Furthermore, PCa patients with high plasma miR-221 concentrations had significant correlation with distant metastasis (P=0.041), and non-resectable status (P=0.021).Conclusion:Plasma miR-221 could be a useful biomarker for cancer detection, monitoring tumour dynamics and predicting malignant outcomes in PCa patients, and may contribute to clinical decision making in PCa treatments.

Background:Recently, it was reported that plasma microRNAs (miRNAs) are low-invasive useful biomarkers for cancer. We attempted to isolate gastric cancer (GC)-associated miRNAs comparing pre- and post-operative paired plasma, thereby excluding the possible effects of individual variability.Methods:This study was divided into four steps: (1) microarray analysis comparing pre- and post-operative plasma; (2) validation of candidate miRNAs by quantitative RT–PCR; (3) validation study of selected miRNAs using paired plasma; and (4) comparison of the levels of selected miRNAs in plasma between healthy controls and patients.Results:From the results of microarray analysis, nine candidate miRNAs the levels of which were markedly decreased in post-operative plasma were selected for further studies. After confirmation of their post-operative marked reduction, two candidate miRNAs, miR-451 and miR-486, were selected as plasma biomarkers, considering the abundance in plasma, and marked decrease in post-operative samples. In validation, the two miRNAs were found to decrease in post-operative plasma in 90 and 93% of patients (both P<0.01). In comparison with healthy controls, the levels of both miRNAs were found to be significantly higher in patients, and the area under the curve values were high at 0.96 and 0.92.Conclusion:Plasma miR-451 and miR-486 could be useful blood-based biomarkers for screening GC.

Background We previously demonstrated the potential of circulating tumor DNA (ctDNA) for the amplification of detecting HER2 in patients with gastric cancer (GC). In the present study, we focused on the clinical courses of patients who developed recurrence with GC, and investigated the potential clinical utility of the ddPCR-based HER2 copy number (CN) as a marker for the temporal and/or spatial heterogeneities of GC during treatment progress. Method We enrolled 30 healthy volunteers and 60 patients with GC who underwent surgery, including 17 patients who developed recurrence. Using ribonuclease P RNA component H1 (RPPH1) as a reference gene, plasma HER2 to RPPH1 ratios (the HER2 ratio) were determined using ddPCR. Results The preoperative plasma HER2 ratio correlated with the tumor HER2 status (p \ 0.001), and sensitivity and specificity were 0.733 and 0.933, respectively.Analyses of plasma samples during the postoperative follow-up periods revealed that high plasma HER2 ratios were detected at the time of recurrence in 7 of 13 cases, which were diagnosed as being HER2 negative at the time of surgery. These results were supported by continuously increasing HER2 ratios thereafter with the progression of recurrent cancer. Conclusion The plasma HER2 ratio determined by ddPCR is a repeatable and noninvasive approach for realtime evaluations of the HER2 status to monitor the effects of treatments for patients with HER2-positive GC and enable treatment options for patients with HER2-negative GC but positive conversion of the HER2 status after recurrence.