Satoru Asami

Survivin as a prognostic factor for osteosarcoma patients.

Purpose: Survivin is one of the apoptosis inhibitor genes and is rarely expressed in adult tissues. However, survivin expression has been detected in various human cancers and correlations have been recognized between the level of expression of this gene in tumors and prognosis. In this study, we investigated the correlations between survivin mRNA expression in osteosarcoma tissues and clinicopathological parameters. Methods: There were 22 osteosarcoma patients in our hospital with paraffin-embedded tissues which could be extracted from biopsy specimens. We used the RT-PCR method after extracting total RNA and conducted a densitometric analysis to determine the ratio of survivin relative to h-GAPDH as an internal marker. Results: Expression of survivin mRNA was detected in all osteosarcoma samples. Patients with metastasis had high survivin mRNA levels in initial biopsy specimens (p<0.01). Moreover, there was a statistically significant difference in survivin mRNA expression between patients with and without metastasis (p<0.01). Conclusion: We concluded that high levels of survivin mRNA expression suggest poor prognosis for osteosarcoma patients.

Upregulation of metallothionein-I mRNA expression in a rodent model for amyotrophic lateral sclerosis.

Metallothionein (MT) mRNA expression was investigated in a rodent model (G93A SOD1 transgenic mouse) for a lethal motor neuron disease, amyotrophic lateral sclerosis (ALS). In 8-wk-old mice that did not yet exhibit motor paralysis, MT-I mRNA expression was already significantly upregulated in the region of the spinal cord responsible for motor paralysis. The expression of another isoform, MT-III, was not changed. In the cerebellum, which is not responsible for motor paralysis in ALS, neither the expression profiles of MT-I nor MT-III were altered. In 16-wk-old mice exhibiting motor paralysis, the expression of MT-I mRNA remained upregulated and the MT-III level tended to be elevated. Although no significant differences were found in the levels of both isoforms in the liver or kidney of 8-wk-old mice, the MT-I mRNA expression level was significantly upregulated in the kidney and liver of 16-wk-old mice. These results indicated that the MT-I isoform, but not the MT-III isoform, is associated with motor neuron death in ALS and suggested that the disease might be a systemic disorder to which the spinal cord is particularly susceptible.

Different patterns in the induction of metallothionein mRNA synthesis among isoforms after acute ethanol administration

The induction of metallothionein (MT) isoform synthesis was investigated in mouse cerebral cortex 18 h after oral ethanol administration. The expression of MT-I isoform mRNA increased in a dose-dependent manner after ethanol loading at doses between 2 g/kg (ethanol/body weight) and 8 g/kg. Lipid peroxide formation, measured as the amount of malondialdehyde-reactive substances, remained at the control level after all of the administered ethanol doses. The expression of MT-III isoform mRNA remained at the control level up until an ethanol loading dose of 4 g/kg and then finally increased to a significant level at a dose of 8 g/kg, which is almost the LD50 for oral ethanol in mice. The different patterns of MT synthesis induction among MT isoforms suggests that the MT-I isoform, which is ubiquitous in mammalian tissues, plays a significant role as an antioxidant. On the other hand, the MT-III isoform, which has a limited tissue distribution, especially in the central nervous system, seems to be implicated in tissue repair and/or protection against critical tissue injury.

Effect of Cell Differentiation for Neuroblastoma by Vitamin K Analogs

BACKGROUND Lack of receptor tyrosine kinase (TrkA), a high-affinity nerve growth factor (NGF) receptor, is closely associated with the malignant progression of neuroblastoma (NB) and its prognosis. Vitamin K3 (VK3) analogs inhibit the activity of protein tyrosine phosphatases (PTPases), which causes hydrolysis of the phosphate groups bound to the tyrosine residues on tyrosine kinase, resulting in sustained tyrosine phosphorylation. METHODS In order to reverse this abnormal NGF/TrkA signal transduction in NB cells, we synthesized new VK3 analogs and examined their activity against NB cells. RESULTS VK3 analogs increased or maintained the expression level of c-fos mRNA in the NB cells, which express the downstream genes of NGF/TrkA signal transduction. Moreover, the expression level of GAP-43 mRNA, which is a marker of neurite outgrowth and neuronal differentiation, was increased and morphological differentiation was also observed. VK3 analogs (especially COOH analog) continued to express c-fos and GAP-43 mRNAs and induced differentiation of NB cells after stimulation of NGF by strong inhibition of PTPase without affecting TrkA autophosphorylation. CONCLUSIONS Vitamin K3 analogs may have potential as clinical therapeutic agents for NB.

Differences in apoptotic signaling and toxicity between dimethylmonothioarsinic acid (DMMTAV) and its active metabolite, dimethylarsinous acid (DMAIII), in HepaRG cells: Possibility of apoptosis cascade based on diversity of active metabolites of DMMTAV

Dimethylmonothioarsinical acid (DMMTAV), a metabolite of arsenosugars (AsSug) and arsenolipids (AsLP), which are major organoarsenicals contained in seafoods, has been a focus of our attention due to its toxicity. It has been reported that the toxicity of DMMTAV differs according to the host cell type and that dimethylarsinous acid (DMAIII), which is a higher active metabolite of inorganic and organo arsenic compounds, may be the ultimate substance. To further elucidate the details of the mechanisms of DMMTAV, we carried out toxicological characterization by comparing DMMTAV and DMAIII using HepaRG cells, which are terminally differentiated hepatic cells derived from a human hepatic progenitor cell line that retains many characteristics, e.g, primary human hepatocytes including the morphology and expression of key metabolic enzymes (P450 s and GSTs, etc.) and complete expression of all nuclear receptors. HepaRG cells were induced to undergo differentiation by DMSO, which result red in increased levels of metabolic enzymes such as P450 and GST, in non-differentiated cells the cellular toxicities of DMMTAV and DMAIII were reduced and the induction of toxicity by DMMTAV was increased by GSH but not by DMAIII. Both DMAIII and DMMTAV induce apoptosis and increase caspase 3/7 activity. DMAIII exposure increased the activity of caspase-9. On the contrary, DMMTAV exposure resulted in markedly elevated activity of caspase-8 as well as caspase-9. These results suggest there are differences between the signaling pathways of apoptosis in DMAIII and DMMTAV and that between their active metabolites. Consequently, the ultimate metabolic substance of toxicity induction of DMMTAV may not only be DMAIII, but may also be partly due to other metabolic substances produced through the activation mechanism by GSH.

Analytical Chemistry in Medical Science and Technology. Continuous measurement of retinoic acid isomers and retinol in a plasmaby column-switching reversed-phase HPLC.

独自の流路系を持つカラムスイッチング高速液体クロマトグラフィー(HPLC)により,レチノイン酸(RA)異性体である13-cis-RA,all-trans-RAと9-cisRAの相互分離を確立した.カラムスイッチングを用いることにより,カラム中に残る生体成分の洗浄が不要となり,カラム洗浄に要する時間が短縮された.又,流路中に独自の流路を加えたことにより,注入した試料を損なうことなく検出できるようになり,より良い感度と再現性が得られた.そのため,1サイクルが25分で生体成分中のRAの連続測定が可能となった.ピーク面積及び高さを用いた絶対検量線法では,共に200ngまでの間で直線の関係を示し,血中濃度を測定するのに十分な結果が得られた.又,メタノール標準試料で0.5～1.9%(n=10,0.26～0.37μg/ml),標準添加血清試料で0.8～2.2%(n=5,0.32及び0.37μg/ml)の再現性が得られた.これらのことにより,従来のRA血中濃度測定の方法よりも簡便性,操作性,再現性の向上が見られ,本法のRA血中濃度測定の有用性が示唆された.