Characterization of the Emerging Enteropathogen Escherichia Albertii Isolated from Urine Samples of Patients Attending Sapporo Area Hospitals, Japan.

Recently, Escherichia albertii has been identified as a causative agent of diarrhea in humans and is often misidentified as diarrheagenic Escherichia coli (DEC), a lactose-nondegrading bacterium. In this study, we performed biochemical characterization, gene possession status, drug susceptibility testing, and sequencing analysis of the strains detected in urine samples. One urea-degrading strain was detected in terms of biochemical characteristics, but was found to be nonurea-degrading by another method, leading to conflicting results. All target strains possessed the E. albertii-specific gene, the DEC common gene eae, and the E. coli 16S rRNA gene. In the drug susceptibility test, all urine-derived strains were sensitive to tetracycline (TC), whereas the JCM 17328 strain was resistant to TC, suggesting that TC is effective against urine-derived E. albertii strains. In 16S rRNA sequencing analysis, the E. albertii strains were ranked at the top of homology, but not in the top one, making it difficult to differentiate them from other strains. In summary, if a suspected lactose-nondegrading E. coli strain was isolated from a urine sample, it could be differentiated from E. albertii by the presence of E. albertii-specific genes.

Mild Glucose Starvation Induces KDM2A-Mediated H3K36me2 Demethylation through AMPK To Reduce rRNA Transcription and Cell Proliferation.

Environmental conditions control rRNA transcription. Previously, we found that serum and glucose deprivation induces KDM2A-mediated H3K36me2 demethylation in the rRNA gene (rDNA) promoter and reduces rRNA transcription in the human breast cancer cell line MCF-7. However, the molecular mechanism and biological significance are still unclear. In the present study, we found that glucose starvation alone induced the KDM2A-dependent reduction of rRNA transcription. The treatment of cells with 2-deoxy-d-glucose, an inhibitor of glycolysis, reduced rRNA transcription and H3K36me2 in the rDNA promoter, both of which were completely dependent on KDM2A in low concentrations of 2-deoxy-d-glucose, that is, mild starvation conditions. The mild starvation induced these KDM2A activities through AMP-activated kinase (AMPK) but did not affect another AMPK effector of rRNA transcription, TIF-IA. In the triple-negative breast cancer cell line MDA-MB-231, the mild starvation also reduced rRNA transcription in a KDM2A-dependent manner. We detected KDM2A in breast cancer tissues irrespective of their estrogen receptor, progesterone receptor, and HER2 status, including triple-negative cancer tissues. In both MCF-7 and MDA-MB-231 cells, mild starvation reduced cell proliferation, and KDM2A knockdown suppressed the reduction of cell proliferation. These results suggest that under mild glucose starvation AMPK induces KDM2A-dependent reduction of rRNA transcription to control cell proliferation.

Nb-doped rutile TiO2: a potential anode material for Na-ion battery.

The electrochemical properties of the rutile-type TiO2 and Nb-doped TiO2 were investigated for the first time as Na-ion battery anodes. Ti(1-x)Nb(x)O2 thick-film electrodes without a binder and a conductive additive were prepared using a sol-gel method followed by a gas-deposition method. The TiO2 electrode showed reversible reactions of Na insertion/extraction accompanied by expansion/contraction of the TiO2 lattice. Among the Ti(1-x)Nb(x)O2 electrodes with x = 0-0.18, the Ti(0.94)Nb(0.06)O2 electrode exhibited the best cycling performance, with a reversible capacity of 160 mA h g(-1) at the 50th cycle. As the Li-ion battery anode, this electrode also attained an excellent rate capability, with a capacity of 120 mA h g(-1) even at the high current density of 16.75 A g(-1) (50C). The improvements in the performances are attributed to a 3 orders of magnitude higher electronic conductivity of Ti(0.94)Nb(0.06)O2 compared to that of TiO2. This offers the possibility of Nb-doped rutile TiO2 as a Na-ion battery anode as well as a Li-ion battery anode.

Inhibition of the mitogen-activated protein kinase pathway results in the down-regulation of P-glycoprotein.

The multidrug resistance gene 1 (MDR1) product, P-glycoprotein (P-gp), pumps out a variety of anticancer agents from the cell, including anthracyclines, Vinca alkaloids, and taxanes. The expression of P-gp therefore confers resistance to these anticancer agents. In our present study, we found that FTI-277 (a farnesyltransferase inhibitor), U0126 [an inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)], and 17-allylamino-17-demethoxygeldanamycin (an inhibitor of heat shock protein 90) reduced the endogenous expression levels of P-gp in the human colorectal cancer cells, HCT-15 and SW620-14. In contrast, inhibitors of phosphatidylinositol 3-OH kinase, mammalian target of rapamycin, p38 mitogen-activated protein kinase, and c-Jun NH(2)-terminal kinase did not affect P-gp expression in these cells. We further found that U0126 down-regulated exogenous P-gp expression in the MDR1-transduced human breast cancer cells, MCF-7/MDR and MDA-MB-231/MDR. However, the MDR1 mRNA levels in these cells were unaffected by this treatment. PD98059 (a MEK inhibitor), ERK small interfering RNA, and p90 ribosomal S6 kinase (RSK) small interfering RNA also suppressed P-gp expression. Conversely, epidermal growth factor and basic fibroblast growth factor enhanced P-gp expression, but the MDR1 mRNA levels were unchanged in epidermal growth factor-stimulated cells. Pulse-chase analysis revealed that U0126 promoted P-gp degradation but did not affect the biosynthesis of this gene product. The pretreatment of cells with U0126 enhanced the paclitaxel-induced cleavage of poly(ADP-ribose) polymerase and paclitaxel sensitivity. Furthermore, U0126-treated cells showed high levels of rhodamine123 uptake. Hence, our present data show that inhibition of the MEK-ERK-RSK pathway down-regulates P-gp expression levels and diminishes the cellular multidrug resistance.

Flavonoids inhibit breast cancer resistance protein-mediated drug resistance: transporter specificity and structure-activity relationship.

PURPOSE: ATP-binding cassette (ABC) transporters, such as P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and multidrug resistance-related protein 1 (MRP1), confer resistance to various anticancer agents. We previously reported that some flavonoids have BCRP-inhibitory activity. Here we show the reversal effects of an extensive panel of flavonoids upon BCRP-, P-gp-, and MRP1-mediated drug resistance. METHODS: Reversal effects of flavonoids upon BCRP-, P-gp-, or MRP1-mediated drug resistance were examined in the BCRP- or MDR1-transduced human leukemia K562 cells or in the MRP1-transfected human epidermoid carcinoma KB-3-1 cells using cell growth inhibition assays. The IC(50) values were determined from the growth inhibition curves. The RI(50) values were then determined as the concentration of inhibitor that causes a twofold reduction of the IC(50) in each transfectant. The reversal of BCRP activity was tested by measuring the fluorescence of intracellular topotecan. RESULTS: The BCRP-inhibitory activity of 32 compounds was screened, and 20 were found to be active. Among these active compounds, 3',4',7-trimethoxyflavone showed the strongest anti-BCRP activity with RI(50) values of 0.012 microM for SN-38 and 0.044 muM for mitoxantrone. We next examined the effects of a panel of 11 compounds on P-gp- and MRP1-mediated drug resistance. Two of the flavones, 3',4',7-trimethoxyflavone and acacetin, showed only low anti-P-gp activity, with the remainder displaying no suppressive effects against P-gp. None of the flavonoids that we tested inhibited MRP1. CONCLUSION: Our present results thus indicate that many flavonoids selectively inhibit BCRP only. Moreover, we examined the structure-BCRP inhibitory activity relationship from our current study.

The identification of two germ-line mutations in the human breast cancer resistance protein gene that result in the expression of a low/non-functional protein.

PURPOSE: We examined the effects of the nine nonsynonymous germ-line mutations/SNPs in the breast cancer resistance protein (BCRP/ABCG2) gene on the expression and function of the protein. MATERIALS AND METHODS: We generated cDNAs for each of these mutants (G151T, C458T, C496G, A616C, T623C, T742C, T1291C, A1768T, and G1858A BCRP) and compared the effects of their exogenous expression in PA317 cells with a wild-type control. RESULTS: PA/F208S cells (T623C BCRP-transfectants) expressed marginal levels of a BCRP protein species (65kDa), which is slightly smaller than wild-type (70kDa), but this mutant did not appear on the cell surface or confer drug resistance. PA/F431L cells (T1291C BCRP-transfectants) were found to express both 70 kDa and 65 kDa BCRP protein products. In addition, although PA/F431L cells expressed 70 kDa BCRP at comparable levels to PA/WT cells, they showed only marginal resistance to SN-38. PA/T153M cells (C458T BCRP-transfectants) and PA/D620N cells (G1858A BCRP-transfectants) expressed lower amounts of BCRP and showed lower levels of resistance to SN-38 compared with PA/WT cells. CONCLUSIONS: We have shown that T623C BCRP encodes a non-functional BCRP and that T1291C BCRP encodes a low-functional BCRP. Hence, these mutations may affect the pharmacokinetics of BCRP substrates in patients harboring these alleles.