Aki Komatsu

Serum microRNA expression profile: miR-1246 as a novel diagnostic and prognostic biomarker for oesophageal squamous cell carcinoma

Background:Recent studies have demonstrated that microRNAs (miRNAs) are stably detectable in blood and can serve as useful biomarkers for cancer.Methods:We performed an miRNA array using serum samples obtained from oesophageal squamous cell carcinoma (ESCC) patients or healthy controls. MiR-1246 was the most markedly elevated in ESCC patients. Therefore, miR-1246 was selected as a candidate for further analysis. The serum miR-1246 level in 46 healthy controls and 101 ESCC patients was evaluated and compared among various clinicopathological characteristics. MiR-1246 expressions in tissue, exosomal, and cellular samples were also examined.Results:Serum miR-1246 alone yielded an receiver-operating characteristic curve area of 0.754, with 71.3% sensitivity and 73.9% specificity for distinguishing ESCC patients from healthy controls. Serum miR-1246 was significantly correlated with the TNM stage and showed to be the strongest independent risk factor for poor survival (HR, 4.032; P=0.017). Unlike the tendency shown in previous reports, miR-1246 was not upregulated in ESCC tissue samples. Furthermore, exosomal miR-1246 did not reflect the abundance in the cell of origin.Conclusion:These data support our contention that serum miR-1246 has strong potential as a novel diagnostic and prognostic biomarker in ESCC, and its releasing mechanism is selective and independent of tissue miRNA abundance.

Strong HLA-DR antigen expression on cancer cells relates to better prognosis of colorectal cancer patients : Possible involvement of c-myc suppression by interferon-γ in situ

Strong HLA‐DR antigen expression on cancer cells relates to better prognosis of colorectal cancer patients, although the precise mechanism is controversial. From an immunological point of view, HLA‐DR antigen, induced by interferon (IFN)‐γ, is required for tumor‐associated antigen recognition by CD4+ T cells. For instance, as reported previously, the expression of HLA‐DR antigen in normal colorectal epithelium immediately adjacent to cancer coincided significantly with the existence of IFN‐γ mRNA in the tissue. From another aspect, IFN‐γ has been revealed to suppress c‐myc expression in vivo through a stat1‐dependent mechanism, which is important for cell growth, cell cycle and chromosome instability. In the present study, strong HLA‐DR‐positive expression on cancer cells was significantly related to better prognosis for colorectal cancer patients. High IFN‐γ mRNA expression in situ indicated significantly less activation of c‐myc mRNA expression. Further, HLA‐DR antigen expression in cancer cells, as well as Dukes stages, was an independent factor for better long‐term survival by multivariate analysis. Taken together, IFN‐γ, which induces HLA‐DR antigens on the cell surface, also suppresses c‐myc expression in situ, and is a possible non‐immunological mechanism involved in the better long‐term survival of colorectal cancer patients. (Cancer Sci 2006; 97: 57– 63)

Quantification of plasma exosome is a potential prognostic marker for esophageal squamous cell carcinoma

Exosomes play important roles in cancer progression. Although its contents (e.g., proteins and microRNAs) have been focused on in cancer research, particularly as potential diagnostic markers, the exosome behavior and methods for exosome quantification remain unclear. In the present study, we analyzed the tumor-derived exosome behavior and assessed the quantification of exosomes in patient plasma as a biomarker for esophageal squamous cell carcinoma (ESCC). A CD63-GFP expressing human ESCC cell line (TE2-CD63-GFP) was made by transfection, and mouse subcutaneous tumor models were established. Fluorescence imaging was performed on tumors and plasma exosomes harvested from mice. GFP-positive small vesicles were confirmed in the plasma obtained from TE2-CD63-GFP tumor-bearing mice. Patient plasma was collected in Chiba University Hospital (n=86). Exosomes were extracted from 100 µl of the plasma and quantified by acetylcholinesterase (AChE) activity. The relationship between exosome quantification and the patient clinical characteristics was assessed. The quantification of exosomes isolated from the patient plasma revealed that esophageal cancer patients (n=66) expressed higher exosome levels than non-malignant patients (n=20) (P=0.0002). Although there was no correlation between the tumor progression and the exosome levels, exosome number was the independent prognostic marker and low levels of exosome predicted a poor prognosis (P=0.03). In conclusion, exosome levels may be useful as an independent prognostic factor for ESCC patients.

Combined Effects of p53 Gene Therapy and Leptomycin B in Human Esophageal Squamous Cell Carcinoma

Background: p53 gene therapy has been examined in several clinical trials, however, the results of those trials have mostly been unsatisfactory due to the low efficacy of this therapy. Leptomycin B (LMB) is an antibiotic originally isolated from Streptomyces that has the ability to inhibit the export of proteins containing a nuclear export signal from the nucleus to the cytoplasm. Currently, it has been shown that p53 protein has a nuclear export signal. In this study, we assessed whether LMB augments the transduced p53 gene effect. Methods: Antiproliferative effect of LMB was assessed in human esophageal squamous cancer cell lines. Accumulation of p53 protein into the nucleus by LMB was observed by fluorescence microscopy. The combined effect of p53 and LMB was evaluated in in vitro experiments. Results: LMB induced cell death in a dose-dependent manner and p53 drastically accumulated in the nucleus after LMB treatment. The combinatory treatment of p53 gene and LMB significantly increases the efficiency compared to either agent alone. Conclusions: Our findings suggest that LMB has a potent ability to augment the effect of the tumor suppressor p53 in esophageal squamous cancer cell lines and that it is a promising component in p53 gene therapy.

Histone Demethylase LSD1 Inhibitors Prevent Cell Growth by Regulating Gene Expression in Esophageal Squamous Cell Carcinoma Cells.

BackgroundThe expression of genes can be influenced by the balance of histone acetylation and/or histone demethylation, with an imbalance of these processes possibly observed in many cancers. The histone demethylase LSD1 inhibitor activity is associated with selective transcriptional regulation and alterations in the gene expression. However, the exact mechanisms underlying the antitumor effects of LSD1 inhibitors are not fully understood.MethodsThe antitumor effects of NCL1, an LSD1 inhibitor, in esophageal squamous cell cancer (ESCC) cell lines were evaluated. A comprehensive analysis of the changes in the gene expression in ESCC cell lines induced by NCL1 was carried out using a microarray analysis. A loss-of-function assay using a siRNA analysis was performed to examine the oncogenic function of the gene.ResultsNCL1 strongly inhibited the cell growth of T.Tn and TE2 ESCC cells and induced apoptosis. According to the microarray analysis, 81 genes in the T.Tn cells and 149 genes in the TE2 cells were up- or down-regulated 2-fold or more by NCL1 exposure. Among these genes, 27 were contained in both cell lines and exhibited similar expression patterns. PHLDB2, one of the genes down-regulated by NCL1, was overexpressed in the ESCC tumor tissues. Moreover, a high expression level of PHLDB2 was found to be significantly correlated with poor prognosis.ConclusionsThe present observations of the comprehensive analysis of the gene expression levels provide insight into the mechanisms underlying the antitumor effects of LSD1 inhibitors in ESCC patients.

ZNF750 Expression Is a Potential Prognostic Biomarker in Esophageal Squamous Cell Carcinoma

Objective: ZNF750, a transcriptional regulator of epidermal differentiation, has been identified as a tumor suppressor in esophageal squamous cell carcinoma (ESCC). The aim of the present study was to investigate the clinical and prognostic significance of ZNF750 expression and to evaluate the effect of ZNF750 knockdown on cell proliferation, migration, and invasion in ESCC. Methods: A total of 124 patients with ESCC who underwent curative esophagectomy were evaluated in this study. The expression of ZNF750 in surgical specimens was immunohistochemically assessed and used in the analysis of clinicopathological features and overall survival (OS). The molecular role of ZNF750 was investigated by ZNF750 knockdown using small interfering RNA (siRNA) in ESCC cell lines. Results: Low ZNF750 expression had a significant correlation with positive lymph node metastasis (p = 0.028). Furthermore, there was a significant relationship between low expression of ZNF750 in ESCC and a poor OS, and a multivariate analysis showed that low ZNF750 expression was an independent prognostic factor (p = 0.020). The cell growth, migration, and invasion were significantly increased by downregulation of ZNF750. Conclusions: The low expression of ZNF750 was significantly associated with a poor prognosis, and ZNF750 expression may, therefore, be a reliable prognostic biomarker in ESCC.

Fra-1 Regulates the Expression of HMGA1, Which is Associated with a Poor Prognosis in Human Esophageal Squamous Cell Carcinoma

BackgroundThe expression of Fos-related antigen 1 (Fra-1) affects tumor progression, migration, and invasion. In this study, we identified the genes regulated by Fra-1 in esophageal squamous cell carcinoma (ESCC).MethodsWe constructed Fra-1 knockdown models via the transfection of small interfering RNA (siRNA) into ESCC cell lines (TE10, TE11). The expression levels of the genes in the knockdown models were analyzed using a microarray and a Biobase Upstream Analysis, while the expression levels of the candidate genes in the primary tumors of surgical specimens obtained from ESCC patients were determined using real-time polymerase chain reaction (PCR) and immunohistochemical staining. The clinicopathological features were then analyzed.ResultsThe Biobase Upstream Analysis showed the high-mobility-group protein-1 (HMGA1) to be a significant gene regulated by Fra-1. Actual binding of Fra-1 to the promotor region of HMGA1 was revealed in subsequent chromatin immunoprecipitation PCR experiments. Patients with a positive HMGA1 expression had a poor prognosis, and a multivariate analysis demonstrated a positive HMGA1 expression to be a significant independent prognostic factor.ConclusionHMGA1 is regulated by Fra-1 in ESCC, and the HMGA1 expression is significantly associated with a poor prognosis in ESCC patients. Downregulation of the HMGA1 expression may become a practical treatment strategy against ESCC in the future.