Okayama University Medical SchoolActa Medica Okayama0386-300X6762013In Vitro Assessment of Factors Affecting the Apparent Diffusion Coefficient of Jurkat Cells Using Bio-phantoms359367ENKazunoriKatashimaMasahiroKurodaMasakazuAshidaTakanoriSasakiTakehitoTaguchiHidenobuMatsuzakiJunMurakamiYoshinobuYanagiMikiHisatomiMarinaHaraHirokazuKatoYuichiOhmuraTomokiKobayashiSusumuKanazawaSosukeHaradaMitsuhiroTakemotoSeiichiroOhnoSeiichiMimuraJunichiAsaumiOriginal Article10.18926/AMO/52009It is well known that many tumor tissues show lower apparent diffusion coefficient (ADC) values, and that several factors are involved in the reduction of ADC values. The aim of this study was to clarify how much each factor contributes to decreases in ADC values. We investigate the roles of cell density, extracellular space, intracellular factors, apoptosis and necrosis in ADC values using bio-phantoms. The ADC values of bio-phantoms, in which Jurkat cells were encapsulated by gellan gum, were measured
by a 1.5-Tesla magnetic resonance imaging device with constant diffusion time of 30sec. Heating at 42℃ was used to induce apoptosis while heating at 48℃ was used to induce necrosis. Cell death after heating was evaluated by flow cytometric analysis and electron microscopy. The ADC values of bio-phantoms including non-heated cells decreased linearly with increases in cell density, and showed a steep decline when the distance between cells became less than 3μm. The analysis of ADC values of cells after destruction of cellular structures by sonication suggested that approximately two-thirds of the ADC values of cells originate from their cellular structures. The ADC values of bio-phantoms including necrotic cells increased while those including apoptotic cells decreased. This study quantitatively
clarified the role of the cellular factors and the extracellular space in determining the ADC values
produced by tumor cells. The intermediate diffusion time of 30msec might be optimal to distinguish
between apoptosis and necrosis.No potential conflict of interest relevant to this article was reported.Okayama University Medical SchoolActa Medica Okayama0386-300X6632012In Vitro Assessment of Factors Affecting the Apparent Diffusion Coefficient of Ramos Cells Using Bio-phantoms263270ENTakanoriSasakiMasahiroKurodaKazunoriKatashimaMasakazuAshidaHidenobuMatsuzakiJunichiAsaumiJunMurakamiSeiichiroOhnoHirokazuKatoSusumuKanazawaOriginal Article10.18926/AMO/48566The roles of cell density, extracellular space, intracellular factors, and apoptosis induced by the molecularly targeted drug rituximab on the apparent diffusion coefficient (ADC) values were investigated
using bio-phantoms. In these bio-phantoms, Ramos cells (a human Burkittｾs lymphoma cell line) were encapsulated in gellan gum. The ADC values decreased linearly with the increase in cell density, and declined steeply when the extracellular space became less than 4 μm. The analysis of ADC values after destruction of the cellular membrane by sonication indicated that approximately 65% of the ADC values of normal cells originate from the cell structures made of membranes and that the remaining 35% originate from intracellular components. Microparticles, defined as particles smaller than the normal cells, increased in number after rituximab treatments, migrated to the extracellular space and significantly decreased the ADC values of bio-phantoms during apoptosis. An in vitro study using bio-phantoms was conducted to quantitatively clarify the roles of cellular factors and of extracellular space in determining the ADC values yielded by tumor cells and the mechanism by which apoptosis changes those values.No potential conflict of interest relevant to this article was reported.Acta Medica Okayama41102005Role of O-6-methylguanine-DNA methyltransferase and effect of O-6-benzylguanine on the anti-tumor activity of cis-diaminedichloroplatinum(II) in oral cancer cell lines984993ENYuMakiJunMurakamiJun-ichiAsaumiHidetsuguTsujigiwaHitoshiNagatsukaSusumuKokeguchiKazuhiroFukuiNorikoKawaiYoshinobuYanagiMasahiroKurodaNoriakiTanakaNagahideMatsubaraKanjiKishi<p>The DNA repair enzyme, O-6-methylguanine-DNA methyltransferase (MGMT) modulates the effectiveness of alkylating agents. However, the relationship between MGMT and the sensitivities to other agents has not been explored. In the present study, the association between MGMT expression and the cellular sensitivity to the platinum agent, CDDP was examined in four human oral cancer cell tines. CDDP depleted MGMT protein and mRNA levels in all four cell tines. Two cell lines with low MGMT expression were sensitive to an alkylating agent, N-methyl-N'-nitro-N-nitrosoguanidine and CDDP, whereas two other cell tines with high MGMT expression were resistant to both agents. Furthermore, the addition of the MGMT inhibitor, O-6-benzylguanine (O-6-BG), invariably enhanced CDDP sensitivity. CDDP depleted MGMT expression, and CDDP sensitivity was enhanced by O-6-BG. These results provide valuable information about the relationship between MGMT expression and CDDP sensitivity in oral cancer chemotherapy. (c) 2005 Elsevier Ltd. All rights reserved.
</p>No potential conflict of interest relevant to this article was reported.SpringerActa Medica Okayama0344-57045612005Effects of histone deacetylase inhibitor FR901228 on expression level of telomerase reverse transcriptase in oral cancer2228ENJunMurakamiJun-ichiAsaumiNorikoKawaiHidetsuguTsujigiwaYoshinobuYanagiHitoshiNagatsukaTetsuyoshiInoueSusumuKokeguchiShojiKawasakiMasahiroKurodaNoriakiTanakaNagahideMatsubaraKanjiKishiWe speculated whether or not the expression level of telomerase reverse transcriptase (hTERT) would be modulated by agents targeting epigenetics in oral cancer cell lines. Although hTERT is known to be targeted by epigenetic changes, it remains unclear how chemoagents targeting epigenetics work on hTERT transcription. In the present study, the epigenetic effects of histone deacetylase (HDAC) inhibitor FR901228 on hTERT transcription were analysed by RT-PCR in oral cancer cell lines. The mRNA expression of hTERT was upregulated after exposure to FR901228 in hTERT-negative Hep2 cells, even in the hTERT highly expressed SAS and KB cells. Moreover, co-treatment of protein synthesis inhibitor cycloheximide (CHX) resulted in the induction of hTERT transcription by FR901228. This suggests that the induction of hTERT by FR901228 requires de novo protein synthesis to some extent and is more likely a direct than an indirect effect on epigenetic changes such as histone acetylation / deacetylation. We further examined the effect of FR901228 on c-myc protein, which is one of the main hTERT transcription activators. FR901228 repressed c-myc protein only in the absence of CHX, dependent of the enhancement of de novo protein synthesis. Our results indicate that c-myc protein is repressed indirectly by FR901228 but may not contribute FR901228-induced hTERT transcription. The present study showed that the HDAC inhibitor FR901228 induced the hTERT gene by a complex mechanism that involved other transcription factors except for c-myc, in addition to the inhibition of histone deacetylation.No potential conflict of interest relevant to this article was reported.Acta Medica Okayama4062004Effects of demethylating agent 5-aza-2 '-deoxycytidine and histone deacetylase inhibitor FR901228 on maspin gene expression in oral cancer cell lines 597603ENJunMurakamiJun-ichiAsaumiYuuMakiHidetsuguTsujigiwaMasahiroKurodaNoriyukiNagaiYoshinobuYanagiTetsuyoshiInoueShojiKawasakiNoriakiTanakaNagahideMatsubaraKanjiKishi<p>Maspin, which belongs to the serine protease inhibitor (serpin) superfamily, has been proposed as a potent tumor suppressor that inhibits cell motility, invasion, angiogenesis, and metastasis. In the present study, we examined the effects of 5-aza-2'-deoxycytidine (5-aza-dC), a demethylating agent, and FR901228, a histone deacetylase (HDAC) inhibitor, on maspin expression in oral cancer cell tines. The expression levels of maspin mRNA were divided into two groups, which was the maspin tow-expressed and high-expressed cell lines in the 12 oral cancer cell lines. The maspin promoter contained only a few methylated CpG sites in the maspin low-expressed cell lines. Moreover, the methylation status was not altered after 5-aza-dC treatment. However, the transcription of the maspin gene was clearly increased following 5-aza-dC treatment in a number of oral cancer cell tines. These results imply that an action of 5-aza-dC is separate from induction of promoter demethylation. Treatment with FR901228 resulted in a time-dependent stimulation of the re-expression of maspin mRNA as early as 4 h after treatment in the maspin downregulated cells. The re-expression of the maspin gene may contribute to the recuperation of biological functions linked to FR901228 such as an inhibitory effect on tumor angiogenesis and cell invasion. These results indicate that maspin and its target genes may be excellent leads for future studies on the potential benefits of FR901228, a HDAC inhibitor, in cancer therapy.</p>
No potential conflict of interest relevant to this article was reported.岡山医学会Acta Medica Okayama0030155811922007食道扁平上皮癌の発癌過程におけるDNAメチル化の役割113117ENTatsuhiroIshiiJunMurakamiKenjiNotoharaHiromiSasamotoTakeshiKambaraYasuhiroShirakawaYoshioNaomotoMamoruOuchidaKenjiShimizuR. JassJeremyNagahideMatsubaraNoriakiTanakaNo potential conflict of interest relevant to this article was reported.Acta Medica Okayama2003Silencing of O6-methylguanine-DNA methyltransferase gene by methylation of an upstream promoter increases the sensitivity of oral cancer cells to alkylating agents used in their chemotherapyENJunMurakamiNo potential conflict of interest relevant to this article was reported.