Effect of miR-433-3p and miR-883b-5p on murine CYP 3A family enzymes in AML12 cells.

Here we searched for microRNAs that could interact with cytochrome P450 (CYP) enzymes in silico, and then investigated their effects on Cyp gene expressions using the cultured mouse liver cell line AML12. Among the mouse Cyp3a genes, some miRNAs were found to interact with Cyp3a11, 13, 16, and 44 by the in silico analysis using the miRWalk2.0 database. In addition to this software, which included twelve miRNA target prediction algorithms, we also applied our in-house-developed Excel VBA algorithm to obtain predictions more efficiently. Finally, two miRNAs, miR-433-3p and miR-883b-5p, were extracted as candidates that interact with Cyp3a genes. To evaluate the effects of these miRNAs on Cyp3a gene expression, we first examined whether they actually interacted with the Cyp3a 3'-untranslated region (3'-UTR) using a luciferase assay system in AML12 cells. We then evaluated whether the expression of each miRNA affected the expression of Cyp3a mRNAs and their transcribed proteins. We found that the transiently expressed miRNAs significantly reduced the reporter activity of the Cyp3a 3'-UTR site in AML12 cells. In addition, the mRNA and protein expressions of the corresponding Cyp3as were significantly decreased in the miRNA-treated AML12 cells. Using cultured cells, we clearly demonstrated that miR-433-3p and miR-883b-5p, which were identified by in silico prediction, actually bind to Cyp3a mRNAs and regulate Cyp gene expressions.

Different expression patterns of hepatic cytochrome P450 s during anaphylactic or lipopolysaccharide-induced inflammation.

Certain physiological states and diseases can alter the expression and activity of cytochrome P450 s (CYPs), which have the potential to cause unexpected adverse effects. We previously demonstrated that lipopolysaccharide (LPS)-induced inflammation attenuates the induction of CYPs by xenobiotics in mouse liver. In this study, to investigate whether anaphylaxis-induced inflammation affects the hepatic CYPs' expression, we examined the effects of ovalbumin (OVA)-induced anaphylaxis on constitutive CYP mRNA and protein expressions. We also compared these effects with those obtained with LPS treatment. In addition, we examined the tumor necrosis factor (TNF) alpha and interleukin (IL)-113 mRNA levels, because these cytokines are known to be induced by LPS treatment and anaphylactic reactions. LPS treatment decreased the constitutively expressed Cyp1a2, Cyp2c29, and Cyp3al 1 mRNAs, and increased the TNFalpha and IL-1beta mRNAs. LPS treatment also decreased the CYP1A2 and CYP3A protein levels. Anaphylaxis, on the other hand, did not change the levels of the constitutively expressed Cyp1a2, Cyp2c29, or Cyp3a1 1 mRNAs, although it increased the TNFalpha and IL-1beta mRNAs, as observed in the LPS-treated mice. These results suggest that anaphylaxis-induced inflammation had less effect than LPS-induced inflammation on these CYPs in the liver. In contrast, we observed that the expressions of Cyp2b10 mRNA and its protein were quite different from those of the other CYPs in both the anaphylactic and LPS-treated mice. Our findings strongly suggest that the alteration of the constitutive CYPs' expression levels during inflammation varies according to the immunostimulation pathway.

Novel morphological features in the death of MCF-7 human breast cancer cells after exposure to anticancer drugs.

Cell death of human breast cancer cell line MCF-7/pDsRed2-Mito, caused by independent- or multi-administration of three anticancer drugs, cyclophosphamide [CPA], doxorubicin [DXR], and 5-fluorouracil [5-FU], was studied using fluorescence and electron microscopy. In our previous study using cell viability assays, microscopic inspection of heterochromatin condensation, a DNA fragmentation assay, and flow cytometric analyses, the death of MCF-7 cells was classified into two groups. The cell death induced by CPA or 5-FU was classified as apoptotic, while the cell death induced by DXR treatment or a mixture of all three anticancer drugs was classified as non-apoptotic. Here, we examined the morphology of the whole cell and its organelles, including the mitochondria, using electron microscopy. Mitochondria are of particular interest because they are the key organelle for the molecular apoptotic-death cascade. To monitor mitochondrial morphology, we used our previously constructed MCF-7/pDsRed2-Mito line, generated by introducing the pDsRed2-Mito vector into MCF-7 cells. The mitochondria in these cells emit red fluorescence. We found that the administration of DXR alone or of all three anticancer drugs together resulted in the clumping of the red-fluorescent materials on both sides of the round dying cells, interrupted by the nucleus. Detailed electron microscopic observation revealed that the novel morphology of the dying MCF-7 cells might be owing, not to destruction of the mitochondrial membrane, but to the tight structure of the nuclear membrane. Other anticancer drugs showed different, characteristic features in electron microscopic images, which suggested that death induced by anti-cancer drugs in the human breast cancer cell line, MCF-7, may result from any of a number of diverse processes.

Construction of a model cell line for the assay of MDR1 (multi drug resistance gene-1) substrates/inhibitors using HeLa cells.

Cancer cells often become resistant to chemotherapy, and induction of the ABC transporter Multi-drug Resistance gene-1 (MDR1) is a major cause. We established a tool for high-throughput screening of substrates and inhibitors of MDR1, using transformed HeLa cells that over-express MDR1. The cDNA for human MDR1 was subcloned into the eukaryotic expression vector pBK-CMV to produce an MDR1 expression vector, pBK-CMV/MDR1. HeLa cells were transfected with pBK-CMV/MDR1 or the empty vector pBK-CMV. Transfection of the vector sequence for MDR1 and its expression were evaluated by genomic PCR and western blotting, respectively. The efficiency of the MDR1 transporter for pumping a substrate out of the transformed cells was evaluated using rhodamine123 (R-123), a mitochondrial dye that is also an MDR1 substrate. After treatment of the MDR1-expressing HeLa cells with MDR1 substrate vinblastin or inhibitors cyclosporin A and verapamil, the amount of R-123 retained in the cells was increased to 2 to 2.3 times the level in untreated MDR1-expressing HeLa cells. The transfection of empty pBK-CMV had no effect on the R-123 retention in HeLa cells, regardless of drug treatment. In conclusion, we have established a model human carcinoma cell line that expresses functional MDR1 and can be used to screen for substrates and inhibitors of MDR1.

Buprenorphine hydrochloride induces apoptosis in NG108-15 nerve cells.

A morphine alkaloid derivative, buprenorphine hydrochloride, induces apoptosis in NG108-15 cells. Apoptosis was detected mainly by apoptosis-specific DNA fragmentation and morphological changes. This apoptosis was dose-dependent and the time-course experiment indicated that DNA fragmentation occurred within 4 h after administration of buprenorphine hydrochloride. Specific inhibitors of the previously characterized apoptotic signal cascade as well as antagonists for opioid receptors were tested. Zn2+, herbimycin A, caspase inhibitors YVAD (Ac-Tyr-Val-Ala-Asp-CHO) and DEVD (Ac-Asp-Glu-Val-Asp-CHO), naloxone and naltrindole had no effect on apoptosis-specific DNA fragmentation. The serine protease inhibitor TPCK (N-tosyl-L-phenylalanyl chloromethyl ketone) specifically inhibited apoptosis-specific DNA fragmentation induced by buprenorphine hydrochloride; however, cell viability measurements revealed that cell death still occurred in NG108-15 cells. Thus TPCK pretreatment before buprenorphine hydrochloride administration induced apoptosis-independent cell death, presumably necrosis, in NG108-15 cells. This suggests that an unidentified serine protease, presumably functioning in the buprenorphine hydrochloride-specific death-signal cascade, could be pivotal for the rapid apoptosis observed in NG108-15 cells upon treatment with buprenorphine hydrochloride.

Metallothionein genes in the nematode Caenorhabditis elegans and metal inducibility in mammalian culture cells.

Genomic DNAs of metallothionein I and II in Caenorhabditis elegans (CeMT-I and CeMT-II) were isolated by YAC library/polytene filter hybridization followed by subcloning of corresponding cosmid clones. Both genes are mapped at chromosome V. Although the similarities of 5'-flanking regions and coding regions have shown only 55-58%, the introns are split at the same position in both genes, indicating that these two genes are originally from the same gene. While several metal responsive elements are conserved among eukaryotes, only one metal responsive element was found in the promoter region in CeMT-II and not in CeMT-I. Indeed, neither of 5'-flanking regions of CeMT-I nor CeMT-II connected to chloramphenicol acetyltransferase reporter gene is responsive to heavy metals in mammalian culture cells by transient transfection analysis. These results would suggest that the metal regulatory factors in C. elegans might be different from those conserved in invertebrates and vertebrates, although the MTs in C. elegans revealed the similarities to mammalian MTs in several points.

Apoptosis of NG108-15 cells induced by buprenorphine hydrochloride occurs via the caspase-3 pathway.

Apoptosis of NG108-15 neuroblastoma x glioma hybrid cells (NG108-15 cells) is induced by a morphine alkaloid derivative, buprenorphine hydrochloride (Bph). In a previous report, we used various apoptosis inhibitors to identify the "death pathway," and found that caspase inhibitors Ac-YVAD-CHO (Ac-Tyr-Val-Ala-Asp-CHO) and Ac-DEVD-CHO (Ac-Asp-Glu-Val-Asp-CHO) did not inhibit this particular apoptosis. Here, we tested Z-VAD-FMK (Z-Val-Ala-Asp[OMe]-CH2F) and Z-DEVD-FMK (Z-Asp[OMe]-Glu-[OMe]Val-Asp[OMe]-CH2F) for their ability to inhibit Bph-induced NG108-15 apoptosis. These tri- or tetra-peptide caspase inhibitors have a fluoromethyl ketone in their C-terminus instead of an aldehyde, and thus are more permeable than Ac-YVAD-CHO and AC-DEVD-CHO. Our observations of DNA ladder formation, cell morphology changes, and caspase-3 activities all indicated that these cell membrane-permeable caspase inhibitors completely inhibited the apoptosis, providing strong evidence that this apoptosis occurs through the caspase cascade "death pathway." Our previous report also showed that pretreatment of NG108-15 cells with TPCK (N-tosyl-L-phenylalanyl chloromethyl ketone) prevented DNA fragmentation and decreased the cell viability in Bph-induced apoptosis. The comparison of caspase-3 activities in Bph-induced samples with or without TPCK pretreatment revealed that caspase-3 was activated in both samples. Taken together, these results indicate that the Bph-induced apoptosis of NG108-15 cells occurs via the conventional caspase-dependent death pathway and that TPCK pretreatment results in a DNA ladder-deficient apoptosis.

Cloning of Xenopus Dr1 (TBP-binding repressor) and its expression in oocytes and early embryos.

With a final goal to study how TBP-binding repressor Dr1 regulates transcription in Xenopus early embryos, we cloned its cDNA from Xenopus liver cDNA library. The cDNA was 1,986 bp long, with the open reading frame coding for 175 amino acids, whose sequence was highly homologous to its human counterpart. Xenopus Dr1 mRNA was expressed from the earliest stage of oogenesis, inherited as maternal mRNA at a high level, but its level became low at and after the neurula stage where RNA synthetic activity is strongly activated. Dr1 mRNA occurred in larger amounts in the animal half than in the vegetal half in 8-cell stage embryos, and in neurula and tailbud stage embryos its distribution was slightly larger in the anterior part than in the posterior part. These data show that Dr1 mRNA is expressed in a temporally and spatially regulated manner, and its occurrence at higher levels in earlier stage embryos may be responsible for their low transcriptional activity.

Cloning of Xenopus TFIIS and its expression in oocytes and early embryos.

The transcriptional factor TFIIS has been cloned from Xenopus laevis. The length of the cDNA is 1668bp and contains the complete open reading frame of 303 amino acids. Xenopus TFIIS has high homologies to its human and mouse counterparts. In Northern blot analyses, TFIIS mRNAs that consisted of four different sizes were expressed relatively highly from the early stages of Xenopus oogenesis. During oocyte maturation, the pattern of Xenopus TFIIS messages showed a transient peak of expression. TFIIS mRNA occurred maternally and its level increased in later stage embryos. These data suggest that TFIIS mRNA is expressed in a developmentally regulated way in Xenopus laevis.