MicroRNAs and Esophageal Squamous Cell Carcinoma

Esophageal cancer is a common cause of cancer death worldwide. Esophageal squamous cell carcinoma (ESCC) is the most predominant type. Certain microRNAs (miRNAs) function in tumorgenesis involved in important biological and pathologic processes. To reveal miRNAs’ signatures of ESCC, we analyzed miRNAs extracted from ESCC cell lines with the microRNA microarray. The significant alterations were confirmed by quantitative real-time PCR using miRNAs extracted from cell lines or patients’ esophageal biopsy tissues. We found that miR-205 and miR-10a were significantly altered in cellular expression, and might be specific for ESCC with potential roles in the pathogenesis. As a result of function studies in miR-205, alterations in miR-205 expression could modulate the phenotype of epithelial cells towards epithelial-mesenchymal transition characterized by reduced abundance of E-cadherin, that is the ESCC-specific miRNA target and inhibit translationally a representative E-cadherin repressor, ZEB1 and ZEB2. Similarly, miR-10a is reported as a tumor suppressor by controlling cell migration/invasion, as it can target homeobox genes. These results provide insight Published online: June 25, 2010 Hajime Isomoto, MD Department of Gastroenterology and Hepatology Nagasaki University Hospital Nagasaki 852-8501 (Japan) Tel. +81 95 819 7481, Fax +81 95 819 7482 , E-Mail hajimei2002 @ yahoo.co.jp © 2010 S. Karger AG, Basel 0012–2823/10/0823–0138$26.00/0 Accessible online at: www.karger.com/dig MicroRNAs and Esophageal Squamous Cell Carcinoma Digestion 2010;82:138–144 139 They can function as oncogenes or tumor suppressors [4] . However, there has been little information on functional roles of miRNAs specific for esophageal cancer. We sought to identify miRNAs which could be specifically expressed and exert distinct biological actions in ESCC cells. miRNA Expression and ESCC in the Literature There have been several studies on the relationship between miRNA expression and ESCC ( table 1 ). Feber et al. [5] reported that small RNAs isolated from 35 frozen esophageal specimens of patients with ESCC and esophageal adenocarcinoma were analyzed using the comprehensive microarray method. As a result, miR-203 and -205 were expressed as being 2to 10-fold lower in squamous cell carcinoma and adenocarcinomas than in normal epithelium. On the other hand, the miR-21 expression was 3to 5-fold higher in both tumors than in normal epithelium. In another report on a microarray basis validating 70 ESCC patients, elevated miR-21 and reduced miR-375 expression were shown in ESCC tissue compared with non-cancerous tissue [1] . Ogawa et al. [6] reported that for the association of miRNAs with prognosis, the high expression levels of 6 of the 72 miRNAs assessed by quantitative reverse transcriptase PCR (RTPCR) correlated with significantly lower survival rates. In particular, the overexpression of miR-129 was identified as a significant and independent prognostic factor in surgically treated ESCC patients. Lee et al. [7] suggested miR-373 would be a potential oncogene through suppressing large tumor suppressor homolog 2 (LATS2) expression. Hiyoshi et al . [8] reported that miR-21 was significantly elevated in ESCC tissues and cell lines. The report suggested that miR-21 could regulate cell proliferation and invasion through suppressing an apoptosisrelated molecule, programmed cell death protein 4. In addition, elevated expression of miR-103 and -107 correlated with poor survival on multivariate analysis [9] . Table 1 summarizes the representative miRNA expression signatures in ESCC and other cancers and their corresponding predictive or confirmed targets. miR-205 and -10a Are Specific for ESCC We sought to determine miRNA expression signatures in ESCC cells and to assess functional roles of the specific miRNA identified. To find specific miRNAs for ESCC cells, total RNAs were extracted from OE21 and Table 1. MicroRNA expression patterns in ESCC in the literature Expression patterns in ESCC O ther cancers Involvem ent microRNA (miR) compared to non-malignant esophageal tissues compared to other histological cancer cell types proved targets miR-21 d [1, 5, 9] d [9] PDCD41, NFIB2, PTEN3, TPM14 d breast ca.5, lung ca., prostate ca., ovarian ca., pancreatic ca., colon ca., gastric ca., AML6, aggressive CLL7, glioblastoma [4], HCC8, cholangioca. [9], adenoca. of esophagus, HNSCC9 [16], SCC of tongue miR-93 d [5] FUS1, E2F110, TP53INP111 d Gastric ca., HCC f ATL12 miR-373 d [7] Rab1113, APC14, LATS215 d testicular germ cell tumor miR-129 d [6] LATS2 f colorectal ca. miR-203 f [5] d [our group] ABL116, DeltaNp63, TP53INP1, SOCS317 d pancreatic ca., ovarian ca., bladder ca., lung ca. [5] f HNSCC, CML18, ALL19 miR-205 f [5] d [our group] f [5] ZEB1, ZEB220, E2F1, E2F5, HER321, ERBB322, PRKCE23, LRP124 d HNSCC [16], SCC of lung [17] f breast ca. [22], prostate ca. [10] miR-10a f [our group] HOXA325, HOXB1, HOXB3, HOXD4, HOXD10 d HNSCC, urothelial ca. [29] f colon ca. miR-375 f [1] PDK126 f HNSCC, prostate ca. -catenin mutated HCC [30] d = Overexpression in ESCC compared the non-cancerous counterparts; f = downregulation 1 Programmed cell death 4; 2 nuclear factor I/B; 3 phosphatase and tensin homolog; 4 tropomyosin 1; 5 cancer; 6 acute myeloid leukemia; 7 chronic lymphocytic leukemia; 8 hepatocellular carcinoma; 9 head and neck squamous cell carcinoma; 10 E2F transcription factor 1; 11 tumor protein p53 inducible nuclear protein 1; 12 adult T-cell leukemia; 13 Rab protein 11; 14 adenomatous polyposis coli; 15 large tumor suppressor, homolog 2; 16 c-abl oncogene 1; 17 suppressor of cytokine signaling 3; 18 chronic myeloid leukemia; 19 acute lymphocytic leukemia; 20 zinc finger E-box binding homeobox; 21 human epidermal growth factor receptor type 3; 22 v-erb-b2 erythroblastic leukemia viral oncogene homolog 3; 23 protein kinase C, epsilon; 24 low-density lipoprotein receptor-related protein 1; 25 homeobox; 26 phosphoinositide-dependent protein kinase-1.