Kengo Saito

Overexpression of stathmin in oral squamous-cell carcinoma: correlation with tumour progression and poor prognosis

Stathmin is an intracellular phosphoprotein that is overexpressed in a number of human malignancies. Our previous study using proteomic profiling showed that significant upregulation of stathmin occurs in oral squamous-cell carcinoma (OSCC)-derived cell lines. In the current study, to determine the potential involvement of stathmin in OSCC, we evaluated the state of stathmin protein and mRNA expression in OSCC-derived cell lines and human primary OSCCs. A significant increase in stathmin expression was observed in all OSCC-derived cell lines examined compared to human normal oral keratinocytes. In immunohistochemistry, 65% of the OSCCs were positive for stathmin, and no immunoreaction was observed in corresponding normal tissues. Real-time quantitative reverse transcriptase–polymerase chain reaction data were consistent with the protein expression status. Moreover, stathmin expression status was correlated with the TNM stage grading. Furthermore, we found a statistical correlation between the protein expression status and disease-free survival (P=0.029). These results suggest that expression of stathmin could contribute to cancer progression/prognosis, and that stathmin may have potential as a biomarker and a therapeutic target for OSCC.

MicroRNA-125b regulates proliferation and radioresistance of oral squamous cell carcinoma.

Background:MicroRNAs (miRNAs) are involved in essential biological activities, and have been reported to exhibit differential expression profiles in various cancers. Our previous study demonstrated that intercellular adhesion molecule-2 (ICAM2) inhibition induces radiosensitisation in oral squamous cell carcinoma (OSCC) cells. Thus, we hypothesised that certain miRNAs play crucial roles in radioresistance in OSCC by regulating ICAM2 expression.Methods:Because predicted target gene analyses revealed that microRNA-125b (miR-125b) potentially regulates ICAM2 mRNA expression, we examined the association between miR-125b and radioresistance. The expression of miR-125b was investigated by real-time quantitative reverse transcriptase–PCR. For a functional analysis, miR-125b was transfected to OSCC-derived cells.Results:A downregulated expression of miR-125b was found in OSCC-derived cell lines and OSCC samples. The miR-125b-transfected cells showed a decreased proliferation rate, enhanced radiosensitivity to X-ray irradiation and diminished ICAM2 mRNA expression. Moreover, miR-125b expression correlated with OSCC tumour staging and survival.Conclusion:These findings suggested that the downregulated miR-125b expression was associated with proliferation and radioresistance mechanisms, probably through ICAM2 signalling. Thus, controlling the expression or activity of miR-125b might contribute to suppressing proliferation and overcoming radioresistance in OSCC.

Identification of cisplatin-resistance related genes in head and neck squamous cell carcinoma.

Resistance to cisplatin is a major obstacle to successful treatment of head and neck squamous cell carcinoma (HNSCC). To investigate the molecular mechanism of this resistance, we compared the gene expression profiles between the cisplatin‐sensitive SCC cell lines (Sa‐3, H‐1 and KB) and the cisplatin‐resistant cell lines established from them (Sa‐3R, H‐1R and KB‐R) using Affymetrix U133 Plus 2.0 microarray. We identified 199 genes differentially expressed in each group. To identify important functional networks and ontologies to cisplatin resistance, the 199 genes were analyzed using the Ingenuity Pathway Analysis Tool. Fifty‐one of these genes were mapped to genetic networks, and we validated the top‐10 upregulated genes by real‐time reverse transcriptase‐polymerase chain reaction. Five novel genes, LUM, PDE3B, PDGF‐C, NRG1 and PKD2, showed excellent concordance with the microarray data. In 48 patients with oral SCC (OSCC), positive immunohistochemical staining for the five genes correlated with chemoresistance to cisplatin‐based combination chemotherapy. In addition, the expression of the five genes predicted the patient outcomes with chemotherapy. Furthermore, siRNA‐directed suppressed expression of the five genes resulted in enhanced susceptibility to cisplatin‐mediated apoptosis. These results suggested that these five novel genes have great potential for predicting the efficacy of cisplatin‐based chemotherapy against OSCC. Global gene analysis of cisplatin‐resistant cell lines may provide new insights into the mechanisms underlying clinical cisplatin resistance and improve the efficacy of chemotherapy for human HNSCC.

Genes and molecular pathways related to radioresistance of oral squamous cell carcinoma cells

To identify genes associated with radioresistant oral squamous cell carcinoma (OSCC), we compared gene expression signatures between OSCC cell lines exhibiting radioresistance and cells with radiosensitivity after X‐ray irradiation in a dose‐dependent manner using Affymetrix GeneChip analysis with Human Genome‐U133 plus 2.0 GeneChip. The microarray data identified 167 genes that were significantly overexpressed in radioresistant cells after X‐ray irradiation. Among the genes identified, 40 were mapped to 3 highly significant genetic networks identified by the Ingenuity Pathway Analysis tool. Gene ontology analysis showed that cancer‐related function had the highest significance. The 40 genes included 25 cancer‐related genes that formed 1 network and were categorized by function into growth and proliferation, apoptosis, and adhesion. Furthermore, real‐time quantitative reverse transcriptase–polymerase chain reaction showed that the mRNA expression levels of the 25 genes were higher in radioresistant cells than in radiosensitive cells in a dose‐dependent manner and in a time‐dependent manner. Our results suggest that the identified genes help to elucidate the molecular mechanisms of the radioresistance of OSCC and could be radiotherapeutic molecular markers for choosing the appropriate radiotherapy for this disease.

Protein expression profiling identifies maspin and stathmin as potential biomarkers of adenoid cystic carcinoma of the salivary glands

Adenoid cystic carcinoma (ACC) is one of the most common malignant tumors of the salivary glands. It tends to grow slowly but is associated with a poor prognosis compared to other malignant salivary gland tumors. To identify specific markers of ACC, we examined protein expression profiling in ACC xenograft and normal salivary glands (NSG) using fluorescent 2‐dimensional differential in‐gel electrophoresis (2‐D‐DIGE), an emerging technique for comparative proteomics, that improves the reproducibility and reliability of differential protein expression analysis between the samples. To identify the proteins, matrix‐assisted laser desorption/ionization time‐of‐flight peptide mass fingerprinting was carried out. Using these strategies, we detected 4 upregulated proteins and 5 downregulated proteins in ACC xenograft. Maspin and stathmin were selected for further analyses. Western blotting and immunohistochemical staining showed a higher expression of these proteins in ACC xenograft and clinical ACC tissue compared to NSG. Furthermore, Expression of these proteins was correlated with the histologic grading of ACC (n = 10). Therefore, our data indicate that maspin and stathmin may be not only useful biomarkers of ACC but also markers of biologic behavior in this tumor.

Hepatitis C Virus Nonstructural 5A Protein Inhibits Lipopolysaccharide-Mediated Apoptosis of Hepatocytes by Decreasing Expression of Toll-Like Receptor 4

BACKGROUND Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) has been shown to modulate multiple cellular processes, including apoptosis. The aim of this study was to assess the effects of HCV NS5A on apoptosis induced by Toll-like receptor (TLR) 4 ligand, lipopolysaccharide (LPS). METHODS Apoptotic responses to TLR4 ligands and the expression of molecules involved in TLR signaling pathways in human hepatocytes were examined with or without expression of HCV NS5A. RESULTS HCV NS5A protected HepG2 hepatocytes against LPS-induced apoptosis, an effect linked to reduced TLR4 expression. A similar downregulation of TLR4 expression was observed in Huh-7-expressing genotype 1b and 2a. In agreement with these findings, NS5A inhibited the expression of numerous genes encoding for molecules involved in TLR4 signaling, such as CD14, MD-2, myeloid differentiation primary response gene 88, interferon regulatory factor 3, and nuclear factor-κB2. Consistent with a conferred prosurvival advantage, NS5A diminished the poly(adenosine diphosphate-ribose) polymerase cleavage and the activation of caspases 3, 7, 8, and 9 and increased the expression of anti-apoptotic molecules Bcl-2 and c-FLIP. CONCLUSIONS HCV NS5A downregulates TLR4 signaling and LPS-induced apoptotic pathways in human hepatocytes, suggesting that disruption of TLR4-mediated apoptosis may play a role in the pathogenesis of HCV infection.

Preparation and characterization of phospholipid-conjugated indocyanine green as a near-infrared probe

We have rationally designed and synthesized a novel near-infrared (NIR) photoactivating probe, designated by iDOPE, in which an indocyanine green (ICG) fluorophore is covalently conjugated with a phospholipid moiety, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), to incorporate into liposome bilayers. NIR irradiation showed that iDOPE retained the optical and fluorescence properties of ICG and demonstrated photoactivator characteristics: fluorescence emission at around 820 nm in a solvent, singlet oxygen production, and concentration-dependent heat generation. Additionally, iDOPE was incorporated into liposome bilayers and maintained stable liposomally formulated iDOPE (LP-iDOPE) over 1week under physiological conditions. We also observed the tumor-specific biodistribution of LP-iDOPE of in vivo xenografts. These findings suggest that LP-iDOPE might be a promising tool for NIR optical imaging, photodynamic therapy, and photothermal therapy.

Lin-7C/VELI3/MALS-3: An Essential Component in Metastasis of Human Squamous Cell Carcinoma

Using proteomic selection, functional verification, and clinical validation, we identified specific down-regulation of Lin-7C/VELI3/MALS-3 (Lin-7C), which marks oral squamous cell carcinoma (OSCC) metastasis. Despite a rarity of sequence variations in the Lin-7C gene in both primary OSCC and OSCC-derived cells, a high prevalence of hypermethylation was detected in the CpG island region that strongly correlated with its down-regulation. Inducible Lin-7C mRNA by experimental demethylation was found in all OSCC cells tested. Overexpression of the Lin-7C gene in an OSCC cell clone does not contribute to underproliferation but results in a noninvasive phenotype with elevated beta-catenin expression. Experimental metastases in multiple organs of immunodeficient mice were inhibited in cells expressing Lin-7C. Finally, the Lin-7C expression status in primary tumors afforded significantly (P<0.001) high accuracy for predicting lymph node metastasis. These results establish Lin-7C as a novel target of early detection, prevention, and therapy for OSCC metastasis.

Inhibition of human coronavirus 229E infection in human epithelial lung cells (L132) by chloroquine: involvement of p38 MAPK and ERK.

Abstract The antiviral effects of chloroquine (CQ) on human coronavirus 229E (HCoV-229E) infection of human fetal lung cell line, L132 are reported. CQ significantly decreased the viral replication at concentrations lower than in clinical usage. We demonstrated that CQ affects the activation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK). Furthermore, p38 MAPK inhibitor, SB203580, inhibits CPE induced by HCoV-229E infection and viral replication. Our findings suggest that CQ affects the activation of MAPKs, involved in the replication of HCoV-229E.

Reactivation of Hepatitis B Virus in Hematopoietic Stem Cell Transplant Recipients in Japan: Efficacy of Nucleos(t)ide Analogues for Prevention and Treatment

We retrospectively reviewed 413 recipients with hematologic malignancies who underwent hematopoietic stem cell transplantation (HSCT) between June 1986 and March 2013. Recipients with antibody to hepatitis B core antigen (anti-HBc) and/or to hepatitis B surface antigen (anti-HBs) were regarded as experiencing previous hepatitis B virus (HBV) infection. Clinical data of these recipients were reviewed from medical records. We defined ≥1 log IU/mL increase in serum HBV DNA from nadir as HBV reactivation in hepatitis B surface antigen (HBsAg)-positive recipients, and also defined ≥1 log IU/mL increase or re-appearance of HBV DNA and/or HBsAg as HBV reactivation in HBsAg-negative recipients. In 5 HBsAg-positive recipients, 2 recipients initially not administered with nucleos(t)ide analogues (NUCs) experienced HBV reactivation, but finally all 5 were successfully controlled with NUCs. HBV reactivation was observed in 11 (2.7%) of 408 HBsAg-negative recipients; 8 of these were treated with NUCs, and fortunately none developed acute liver failure. In 5 (6.0%) of 83 anti-HBc and/or anti-HBs-positive recipients, HBV reactivation occurred. None of 157 (0%) recipients without HBsAg, anti-HBs or anti-HBc experienced HBV reactivation. In HSCT recipients, HBV reactivation is a common event in HBsAg-positive recipients, or in HBsAg-negative recipients with anti-HBc and/or anti-HBs. Further attention should be paid to HSCT recipients with previous exposure to HBV.