MicroRNA-19 (miR-19) regulates tissue factor expression in breast cancer cells.

Tissue factor has been recognized as a regulator of tumor angiogenesis and metastasis. The tissue factor gene is selectively expressed in highly invasive breast cancer cells, and the mechanisms regulating tissue factor expression in these cells remain unclear. This study demonstrates that microRNA-19 (miR-19) regulates tissue factor expression in breast cancer cells, providing a molecular basis for the selective expression of the tissue factor gene. Tissue factor protein was barely detectable in MCF-7, T47D, and ZR-75-1 cells (less invasive breast lines) but was expressed at a significantly higher level in MDA-MB-231 and BT-20 cells (invasive breast lines) as assayed by Western blot. The tissue factor gene promoter was activated, and forced expression of tissue factor cDNA was achieved in MCF-7 cells, implying that the 3'-UTR of the tissue factor transcript is responsible for the suppression of tissue factor expression. Bioinformatics analysis predicted microRNA-binding sites for miR-19, miR-20, and miR-106b in the 3'-UTR of the tissue factor transcript. Reporter gene assay using the TF-3'-UTR luciferase reporter construct confirmed that the 3'-UTR negatively regulates gene expression in MCF-7 cells, an effect reversed by deletion of the miR-19-binding site. Application of the miR-19 inhibitor induces endogenous tissue factor expression in MCF-7 cells, and overexpression of miR-19 down-regulates tissue factor expression in MDA-MB-231 cells. RT-PCR analysis using cDNA made from Ago2-immunoprecipitated RNA samples confirmed that Ago2 binds preferentially to tissue factor 3'-UTR in MCF-7 cells, as compared with MDA-MB-231 cells, consistent with the observation that miR-19 levels are higher in MCF-7 cells.

Docosahexaenoic acid inhibits superoxide dismutase 1 gene transcription in human cancer cells: the involvement of peroxisome proliferator-activated receptor alpha and hypoxia-inducible factor-2alpha signaling.

Docosahexaenoic acid (DHA; n-3, 22:6) is known to have anticancer activity, but its mechanisms of action remain to be further elucidated. We recently demonstrated that DHA down-regulates superoxide dismutase (SOD) 1 gene expression, thereby weakening cellular antioxidant forces and enhancing cytotoxicity in various human cancer cells. The objective of this study was to investigate the mechanism of the inhibitory effect of DHA on SOD-1 gene expression in human cancer cells. A reporter gene assay indicated that DHA suppresses SOD-1 gene transcription in a time- and concentration-dependent manner in human cancer cells. Pretreatment with vitamin E did not block the inhibitory effect of DHA, indicating that this suppression does not depend on lipid peroxidation. The suppressive effect of DHA on SOD-1 gene transcription could be mimicked by the peroxisome proliferator-activator receptor (PPAR) alpha ligand clofibrate but not the PPARgamma ligand troglitazone, suggesting the involvement of PPARalpha signaling. Deletion analysis of the key DNA binding elements in the SOD-1 gene promoter identified the distal hypoxia response element (HRE), but not the peroxisome proliferator response element or nuclear factor-kappaB element, as essential for the suppressive effects of DHA. Coimmunoprecipitation confirmed that PPARalpha, but not PPARgamma, forms a complex with hypoxia-inducible factor (HIF)-2alpha in cancer cells. Chromatin immunoprecipitation analysis indicated that both DHA and clofibrate reduce HIF-2alpha binding to the HRE. Thus, we have identified the distal HRE in the SOD-1 gene promoter that mediates the suppression on the transcription of this gene by DHA, and we have demonstrated the involvement of PPARalpha and HIF-2alpha signaling in this event.

Quality control analytical methods: microbial limit tests for nonsterile pharmaceuticals, Part 1.

Contamination of pharmaceuticals with microorganisms may lead to deleterious effects on the therapeutic properties of the drug, and may potentially cause injuries to intended recipients. Cases of contaminated nonsterile products have been reported in increasing numbers, and often associated with the presence of objectionable microorganisms. Methods for detection of these organisms are described in three major Pharmacopeias. Their functions and their limitations in the examination of microbiological quality for nonsterile products will be reviewed in this report.

Quality Control: microbial limit tests for nonsterile pharmaceuticals, part 2.

Cases of contaminated nonsterile products have been reported in increasing numbers. Often, these contaminated products are associated with the presence of objectionable microorganisms. The major contaminants of nonsterile pharmaceutical products and ingredients are bacteria, yeasts, and molds. The combination of parts 1 and 2 of this series of articles provides a thorough examination of microbiological quality testing for nonsterile products.

Clioquinol independently targets NF-kappaB and lysosome pathways in human cancer cells.

We have reported that clioquinol alters lysosome integrity, inhibits nuclear factor kappa B (NF-kappaB) activity, and induces apoptosis in human cancer cells. The present study investigated whether clioquinol targets both pathways dependently or independently in human prostate cancer DU 145 cells. Clioquinol inhibited NF-kappaB activity, an effect being more pronounced in the presence of zinc. This inhibition was mediated through a reduced nuclear level of p65, the most frequently detected NF-kappaB subunit. Clioquinol also induced alterations of lysosome permeability in a zinc concentration-dependent manner. Pretreatment of the cells with ammonium, a lysosome protection agent, attenuated clioquinol-induced disruption of the lysosomes, yet ammonium had no effect on clioquinol-induced inhibition of NF-kappaB signaling. MG132, an established NF-kappaB inhibitor, suppressed NF-kappaB activity without causing alterations of lysosome permeability. These findings indicate that clioquinol targets NF-kappaB and lysosome pathways independently, favoring further development of clioquinol as a novel anticancer agent.

Transient metals enhance cytotoxicity of curcumin: potential involvement of the NF-kappaB and mTOR signaling pathways.

BACKGROUND/AIM: Curcumin has been recognized as a metal-binding compound and an anticancer agent, yet the involvement of metals in the anticancer action of curcumin remains unclear. The present study examined the role of transient metals in curcumin-induced cytotoxicity in cancer cells. MATERIALS AND METHODS: Metal-binding activity and cytotoxicity of curcumin were examined in human cancer lines with cell viability assay, confocal microscopy, Western blot, and measurement of hydrogen peroxide generation. RESULTS: It was found that Cu (II) most significantly potentiated the cytotoxicity of curcumin among the metals tested. The combination of curcumin and Cu (II) did not generate reactive oxygen species and vitamin E did not block the cytotoxicity. Curcumin plus Cu (II) enhanced intracellular copper levels and potentiated curcumin-induced suppression of the nuclear factor kappa B (NF-κB) pathway, as well as alterations of mammalian target of rapamycin-raptor (mTOR) signaling. CONCLUSION: Transient metals enhance the cytotoxicity of curcumin, likely through targeting of the NF-κB and mTOR signaling pathways.

N-Acetylcysteine interacts with copper to generate hydrogen peroxide and selectively induce cancer cell death.

A variety of metal-binding compounds have been found to exert anti-cancer activity. We postulated that N-acetylcysteine (NAC), which is a membrane-permeable metal-binding compound, might have anti-cancer activity in the presence of metals. We found that NAC/Cu(II) significantly alters growth and induces apoptosis in human cancer lines, yet NAC/Zn(II) and NAC/Fe(III) do not. We further confirmed that this cytotoxicity of NAC/Cu(II) is attributed to reactive oxygen species (ROS). These findings indicate that the combination of Cu(II) and thiols generates cytotoxic ROS that induce apoptosis in cancer cells. They also indicate a fourth class of anti-neoplastic metal-binding compounds, the "ROS generators".

PPARalpha signaling mediates the synergistic cytotoxicity of clioquinol and docosahexaenoic acid in human cancer cells.

This study investigated the involvement of PPARgamma and PPARalpha signaling in the synergistic anticancer activity of clioquinol (5-chloro-7-iodo-8-hydroxyquinoline) and docosahexaenoic acid (DHA) in human cancer cells. The synergistic cytotoxicity of DHA and clioquinol was demonstrated in nine human cancer cell lines representing different tissues of origin. A2780, a well-established ovarian cancer model system, was chosen for further characterization because of its sensitivity to DHA and clioquinol. Both PPARalpha and PPARgamma were expressed in A2780 cells when analyzed with western blotting and reporter gene technique. Treatment of the cells with clofibrate (a PPARalpha agonist) and clioquinol for three days mimicked the synergy of DHA and clioquinol, whereas this synergy could not be seen with the use of troglitazone (a PPARgamma agonist) and clioquinol, suggesting that PPARalpha signaling is involved in the synergistic action. When used alone, the IC50 of clofibrate was 513 microM in A2780 cells. However, the addition of 5 microM clioquinol to clofibrate-treated cells led to a dramatic reduction of its IC50 value (148 microM). The combination effects index (CI) analysis confirmed the synergy of clioquinol and clofibrate on inhibiting cancer cell viability. Using inhibitors to block PPARalpha signaling diminished the synergistic cytotoxicity of clioquinol and DHA. These results provide pharmacological evidence that the synergistic anticancer action of clioquinol and DHA is mediated by PPARalpha signaling in human cancer cells.