Hirotaka Konishi

Circulating microRNAs in plasma of patients with gastric cancers

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=0.05, 0.006, 0.008 and <0.001 respectively), whereas let-7a was lower in GC patients (P=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.

Circulating microRNAs in plasma of patients with oesophageal squamous cell carcinoma

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.

Clinical impact of circulating miR-221 in plasma of patients with pancreatic cancer

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.

Clinical impact of circulating miR-18a in plasma of patients with oesophageal squamous cell carcinoma

Background:Several recent studies demonstrated that microRNAs are stably detectable in plasma/serum. We tested whether miR-18a, which is located in the miR-17-92 cluster and reported to be highly expressed in tissues of oesophageal squamous cell carcinoma (ESCC), served as a plasma biomarker in patients with ESCC.Methods:This study was divided into three steps: (1) confirmation of higher miR-18a levels in primary ESCC tissues and cell lines than normal ESCC tissues and a human fibroblast cell line. (2) Evaluation of the plasma miR-18a assay using quantitative RT–PCR by comparing results from 106 consecutive patients with ESCC and 54 healthy volunteers. (3) Evaluation of the assay for monitoring tumour dynamics in patients with ESCC.Results:(1) Expression of miR-18a was significantly higher in ESCC tissues (P=0.0020) and ESCC cell lines (P=0.0121) than normal tissues and fibroblasts. (2) Plasma concentrations of miR-18a were significantly higher in ESCC patients than healthy volunteers (P<0.0001; ESCC patients vs healthy volunteers (mean±s.d.): 11.77±13.45 vs 0.73±0.54 amol μl−1). The value of the area under the receiver-operating characteristic (ROC) curve (AUC) was 0.9449. Furthermore, the ROC curves to detect early ESCC such as pTis-1 and pStage0-I showed AUCs of 0.9479 and 0.9642, respectively. (3) Plasma levels of miR-18a were significantly lower in postoperative samples than preoperative samples (P=0.0076).Conclusion:Plasma miR-18a may be a very useful biomarker for cancer detection and the monitoring of tumour dynamics in patients with ESCC.

Prognostic impact of circulating miR-21 and miR-375 in plasma of patients with esophageal squamous cell carcinoma

Background: miR-21 and miR-375 are reported to be highly and poorly expressed in esophageal squamous cell carcinoma (ESCC) tissues, respectively. Recently, we demonstrated that circulating miR-21 and miR-375 were stably detectable in plasma and reflected tumor dynamics as a tumor marker for ESCC. We hypothesized that these plasma miRNA concentrations contributed to prognostic markers in patients with ESCC. Methods: Between 2008 and 2010, 50 preoperative plasma samples were collected from consecutive patients with ESCC, who underwent curative esophagectomy in our hospital. We examined the association between plasma miRNA concentrations and prognosis retrospectively. Results: i) The postoperative cause-specific survival rate of patients with high plasma miR-21 concentration tended to be poorer than low group (3-yr survival rate: 53.4 and 81.5%, p = 0.1038), while that of high plasma miR-375 group was better than low group (3-yr survival rate: 100 and 65.2%). ii) Patients with high miR-21 and low miR-375 concentrations in plasma had significantly poorer prognosis than other patients (3-yr survival rate: 48.4 and 83.1%, p = 0.039). Multivariate analysis revealed that the presence of high miR-21 and low miR-375 concentrations in plasma was an independent prognostic factor (p = 0.029, hazard ratio 3.8 (1.14-12.5)). Conclusion: Circulating miR-21 and miR-375 could be reliable prognostic markers for ESCC. These plasma markers might facilitate clinical decision-making to select prospective candidates, which need meticulous follow-up for early detection of recurrences and additional treatments such as neo-adjuvant chemotherapy and postoperative chemotherapy in ESCC.

Circulating MicroRNA in Digestive Tract Cancers

d t For many decades, cell-free nucleic acids have been known to be present in peripheral blood. Several tudies have identified tumor-specific and/or tumor-assoiated alterations in the circulating nucleic acids of paients with various cancers. In recent years, cell-free miroRNA (miRNA) have been stably detected in the plasma nd serum, like other molecules; their presence in the lood has attracted the attention of researchers due to heir potential use as valuable blood biomarkers.1 MiRNAs are short, noncoding RNAs that play important roles in various physiologic and developmental processes. The mature miRNAs are produced from long primary transcripts through 2 sequential cleavage steps. The long primary miRNA transcript is cleaved by the Drosha complex in the nucleus, generating intermediate precursor miRNA. Precursor miRNA is transported by exportin-5 from the nucleus into the cytoplasm, and then subjected to further cleavage by a Dicer RNAase III enzyme, generating a short double-strand miRNA. One strand (guided strand) of mature miRNA is then incorporated into the RNA-induced silencing complex and subsequently hybridize to the 3=-untranslated region of their target mRNAs to repress translation or degrade these mRNAs. Thus, a single miRNA can influence the expression of hundreds of genes and allow them to function in a coordinated manner. Therefore, miRNAs have been implicated as key molecules in all cellular processes. Numerous studies have shown that alterations in miRNA expression correlate with various diseases, including the development and progression of cancer, and some miRNAs can function as oncogenes or tumor suppressors. These findings have opened up a new and interesting field in the diagnosis of cancer and the treatments of cancer patients. Mitchell et al2 first demonstrated that circulating miRNAs had the potential to be new biomarkers in patients with solid cancers. In recent years, several papers have demonstrated that circulating miRNAs can also be detected in the peripheral blood of patients with digestive tract cancers. Although the origins and physiologic functions of cell-free miRNAs in the blood remain to be fully elucidated, a noninvasive assay for miRNAs should be developed to exploit these molecules as potential diagnostic and prognostic biomarkers. This assay undoubtedly contributes to an improvement in the clinical outcomes of cancer patients. In this article, we review the current state of biological and clinical research regarding circulating miRNAs of digestive tract cancer patients and discuss the future perspectives.

Fluorescent detection of peritoneal metastasis in human colorectal cancer using 5-aminolevulinic acid

A precise diagnosis of peritoneal dissemination is necessary to determine the appropriate treatment strategy for colorectal cancer. However, small peritoneal dissemination is difficult to diagnose. 5-aminolevulinic acid (5-ALA) is an intermediate substrate of heme metabolism. The administration of 5-ALA to cancer patients results in tumor-specific accumulation of protoporphyrin IX (PpIX), which emits red fluorescence with blue light irradiation. We evaluated the usefulness of photodynamic diagnosis (PDD) using 5-ALA to detect the peritoneal dissemination of colorectal cancer. EGFP-tagged HT-29 cells were injected into the peritoneal cavity of BALB/c nude mice. After 2 weeks, the mice were given 5-ALA hydrochloride, and metastatic nodules in the omentum were observed with white light and fluorescence images. Twelve colorectal cancer patients suspected to have serosal invasion according to preoperative computed tomography (CT) were enrolled in this study. 5-ALA (15-20 mg per kg body weight) was administered orally to the patients 3 h before surgery. The abdominal cavity was observed under white light and fluorescence. Fluorescence images were analyzed with image analysis software (ImageJ 1.45s, National Institutes of Health, Bethesda, MD, USA). The mice developed peritoneal disseminations. The observed 5-ALA-induced red fluorescence was consistent with the EGFP fluorescent-positive nodules. Peritoneal dissemination was observed with conventional white light imaging in 8 patients. All nodules suspected as being peritoneal dissemination lesions by white light observation were similarly detected by ALA-induced fluorescence. In 1 patient, a small, flat lesion that was missed under white light observation was detected by ALA-induced fluorescence; the lesion was pathologically diagnosed as peritoneal metastasis. In the quantitative fluorescence image analysis, the red/(red + green + blue) ratio was higher in the metastatic nodules compared to the non-metastatic sites of the abdominal wall, fat and liver. We demonstrated better diagnostic accuracy using 5-ALA-PDD compared to conventional laparoscopy in patients with colorectal cancer. 5-ALA-PDD is a promising candidate method for diagnosing peritoneal dissemination of colorectal cancer.

Plasma level of metastasis‐associated lung adenocarcinoma transcript 1 is associated with liver damage and predicts development of hepatocellular carcinoma

Recent studies have shown that metastasis‐associated lung adenocarcinoma transcript 1 (MALAT1) was overexpressed in many human solid cancers, however, its roles in plasma of hepatocellular carcinoma (HCC) patients were unclear. The aim of this study was to investigate the significance of plasma MALAT1 levels in HCC patients. Plasma samples were collected from pre‐operative HCC, hepatic disease patients, and healthy controls, and tissue samples from HCC patients and colorectal cancer patients with liver metastasis. Plasma and tissue MALAT1 levels were measured. Plasma MALAT1 levels were progressively and significantly higher in HCC patients than hepatic disease patients, and higher in hepatic disease patients than healthy controls. The expression of MALAT1 in HCC tissue was slightly higher than that in paired non‐cancerous liver tissue, but not significant. The expression of MALAT1 in the non‐cancerous liver tissue of 20 HCC patients was significantly higher than that in normal liver tissue of 13 colorectal cancer patients. In contrast, plasma MALAT1 levels were significantly low in HCC patients with hepatitis B infection, and significantly high in patients with liver damage B or liver cirrhosis. In a receiver–operator curve analysis of HCC and hepatic disease patients, the cut‐off value of plasma MALAT1 was 1.60 and the area under the curve was 0.66. Plasma MALAT1 levels were not correlated with α‐fetoprotein or protein induced by vitamin K absence II, whereas sensitivity and specificity for the detection of HCC with the combination of MALAT1, α‐fetoprotein, and protein induced by vitamin K absence II were 88.6% and 75%, respectively. In conclusion, the plasma MALAT1 level is associated with liver damage, and has clinical utility for predicting development of HCC.

Overexpression of TRIM44 contributes to malignant outcome in gastric carcinoma.

Recent studies have shown that some members of the tripartite motif‐containing protein (TRIM) family, which is characterized by a conserved RING finger, B‐box, and coiled‐coil domains, function as important regulators for carcinogenesis. In this study, we tested whether TRIM44 (11p13) acts as a cancer‐promoting gene through overexpression in gastric cancer. We analyzed seven gastric cancer cell lines and 112 primary tumors, which were curatively resected in our hospital between 2001 and 2003. Expression of the TRIM44 protein was detected in gastric cancer cell lines (2/7 cell lines; 29%) and primary tumor samples of gastric cancer (29/112 cases; 25%). Knockdown of TRIM44 expression using several specific siRNAs inhibited the proliferation, migration, and invasion of TRIM44‐overexpressing cells. Overexpression of the TRIM44 protein was significantly correlated with an advanced type of macroscopic appearance, lymphatic invasion, and higher recurrence rate. TRIM44‐overexpressing tumors had a worse overall rate of survival than those with non‐expressing tumors (P = 0.0038, log–rank test) in both intensity and proportion expression‐dependent manner. TRIM44 positivity was independently associated with worse outcome in multivariate analysis (P = 0.0233, hazard ratio 3.37 [1.18–9.64]). These findings suggest that TRIM44 plays a crucial role in tumor cell proliferation through its overexpression, and highlight its usefulness as a predictor and potential therapeutic target in gastric cancer.

Plasma microRNA profiles: identification of miR-744 as a novel diagnostic and prognostic biomarker in pancreatic cancer

Background:This study aims to explore novel microRNAs in plasma for screening cancer and predicting clinical outcomes in pancreatic cancer (PCa) patients using a microRNA array-based approach.Methods:We used the Toray 3D-Gene microRNA array-based approach to compare plasma levels between PCa patients and healthy volunteers.Results:(1) Six oncogenic microRNAs (miR-615-5p, -744, -575, -557, -675, and -550a) with high expression in plasma were selected. (2) By quantitative RT–PCR using plasma samples from 94 PCa patients and 68 healthy volunteers, a significantly higher level of plasma miR-744 in PCa patients than in healthy volunteers was validated in small-scale analysis (P=0.0038), two independent cohort analyses, and large-scale analysis (P<0.0001, AUC 0.8307). (3) miR-744 expression was significantly higher in PCa tissues (P=0.0069) and PCa cell lines (P=0.0074) than in normal tissues and fibroblasts, respectively. Preoperative plasma level of miR-744 was significantly reduced in postoperative samples (P=0.0063). (4) A high level of plasma miR-744, which was correlated with lymph node metastasis (P=0.0407) and recurrences (P=0.0376), was an independent poor prognostic factor of PCa patients after pancreatectomy (P=0.0007, HR 21.2 (3.17–436)). Furthermore, a high level of plasma miR-744 contributed to poorer progression-free survival of non-operable PCa patients who underwent gemcitabine-based chemotherapy (P=0.0533). Overexpression of miR-744 in PCa cells induced significant chemoresistance to gemcitabine in vitro.Conclusions:Plasma miR-744 might be useful biomarker for screening PCa, monitoring, and predicting poor prognosis and chemoresistance in PCa patients.