Nobuya Sakai

Himeji Dokkyo University, Himezi, Hyōgo, Japan

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Publications (3)9.27 Total impact

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    ABSTRACT: Effective detection of potential nephrotoxicity is crucial for pre-clinical drug development. We evaluated a sensitive animal model for drug-induced kidney injury, which includes hemi-nephrectomy of mice. Although bucillamine and d-penicillamine are used for the treatment of rheumatoid arthritis in Japan, drug-related adverse effects on the kidney can limit their therapeutic utilities. When bucillamine (1000 or 2000 mg/kg/day) or d-penicillamine (2000 mg/kg/day) were orally administered to hemi-nephrectomised BALB/c mice, the urinary protein levels of bucillamine-treated mice, but not of those treated with d-penicillamine, the vehicle, or in bucillamine treated unnephrectomized mice, were significantly increased and remained high during the 4-week drug-loading period. Membranous glomerulonephropathy occasionally seen in bucillamine/d-penicillamine-treated arthritis patients was not reproduced in mice. Instead, our mouse model showed proximal tubular injury and podocyte foot process effacement in the bucillamine-treated kidneys. These two cell types are also the primary targets of the experimental Heymann membranous glomerulonephropathy. Gene expression profiling of the bucillamine-treated mice identified lipocalin 2 as a significantly up-regulated transcript together with cytochrome P450 CYP4a14, a group-specific component, and proprotein convertase subtilisin/kexin type 9. Moreover, large amounts of lipocalin 2 were detected in the urine of the bucillamine-treated mice, but not in the hemi-nephrectomised control mice. These results indicate that hemi-nephrectomy effectively promotes acute kidney injury by bucillamine, which is accompanied by up-regulation of the urinary biomarker lipocalin 2. Our mouse model with initial stage of kidney injury should be useful to analyse the pathogenesis of drug-induced glomerular and tubular injuries.
    European journal of pharmacology 09/2011; 670(1):208-15. · 2.59 Impact Factor
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    ABSTRACT: Patients with clinical stage I/II (T1-2N0M0) oral tongue squamous cell carcinoma (TSCC) usually undergo partial glossectomy alone. However, 14-48% of them develop delayed neck metastasis (DNM), which may lead to an unfavorable course. Recently epithelial-to-mesenchymal transition (EMT) has been thought to play a crucial role in cancer metastasis. The present study aimed to examine the associations of EMT-involved molecular factors and clinicopathological factors with DNM in stage I/II TSCC. mRNA expression levels of E-cadherin and its transcriptional repressors (snail, SIP1, and twist) in 7 head and neck squamous cell carcinoma (HNSCC) cell lines were evaluated by quantitative real-time PCR. Clinicopathological parameters and immunohistochemical expressions of E-cadherin and its repressors were examined in surgical specimens of 37 stage I/II TSCC patients who underwent partial glossectomy alone. In HNSCC cells, E-cadherin expression was inversely correlated with SIP1 expression (P = 0.023). Univariate analysis of immunohistochemistry showed that overexpression of SIP1 and loss of E-cadherin were significantly correlated with DNM, although no inverse correlation was found between E-cadherin and its repressors. Multiple logistic regression analysis including clinicopathological and molecular factors revealed that overexpression of SIP1 (P = 0.005), loss of E-cadherin (P = 0.046), and vascular invasion (P = 0.024) were independently correlated with DNM. These results suggest that development of DNM in stage I/II TSCC is closely related to induction of EMT in primary tumor cells. Especially, SIP1 and E-cadherin are considered to be the possible markers for selecting patients at high risk of DNM.
    Annals of Surgical Oncology 09/2011; 19(2):612-9. · 4.12 Impact Factor
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    ABSTRACT: A noncoding RNA, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), is upregulated in several malignant tumors. Its expression in neuroblastoma, however, is not known, and the regulatory mechanisms of MALAT1 gene expression have not been elucidated. The aim of this study is to clarify how MALAT1 gene expression is altered by extracellular signals in the SK-N-SH neuroblastoma cell line and to define its proximal promoter in order to study the mechanism of MALAT1 gene expression. Transcript amounts were analyzed by real-time semiquantitative polymerase chain reaction (qPCR). Genes coregulated with MALAT1 were identified by DNA microarray analysis. The structure of the MALAT1 transcript was delineated using a tiling microarray, and the 5'-end was determined using the rapid amplification of cDNA ends (RACE) method. We investigated binding of the cyclic AMP-responsive element binding (CREB) transcription factor to the MALAT1 promoter by using chromatin immunoprecipitation (ChIP) followed by tiling array analysis, and the results were confirmed using ChIP-qPCR. The posterior pituitary hormone oxytocin increased the levels of MALAT1 and immediate early gene transcripts as early as 15 min after stimulation. Although the expression of immediate early genes returned to basal levels after 3h, MALAT1 transcript levels peaked 6-24h after stimulation. We identified a shorter transcriptional initiation site and found that CREB binds to the defined proximal promoter of the MALAT1 gene. The expression of the tumor marker MALAT1 ncRNA is sensitive to cell surface receptor activation by oxytocin in a neuroblastoma cell line.
    Life sciences 02/2010; 86(11-12):455-60. · 2.56 Impact Factor