Induction of apoptosis by morphine in human tumor cell lines in vitro.

Most previous studies of the induction of tumor cell apoptosis by morphine have been conducted with concentrations very much higher than those used clinically. An investigation of the ability of morphine to induce apoptosis at its clinical concentration (10(-8) M) was therefore undertaken. Cytotoxicity was tested by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, induction of early apoptosis and necrosis by fluorescence-activated cell sorter (FACS) analysis with Annexin V and propidium iodide (PI), activation of caspase -2, -3, -8 and -9 by cleavage of specific substrates, DNA fragmentation by agarose gel electrophoresis, radical intensity and O2- scavenging activity by ESR spectroscopy. Millimolar concentrations of morphine showed higher cytotoxicity against human tumor cell lines (HL-60, A549, MCF7) than against normal human cells (HGF, HPC, HPLF). The clinical concentration of morphine produced early apoptotic markers in HL-60 and A549 cells whereas it induced higher numbers of necrotic cells in MCF7 cells, both in a naloxone-sensitive manner. The clinical concentration of morphine failed to activate any caspase species and induced only trace amounts of internucleosomal DNA fragmentation, in contrast to cytotoxic concentrations of morphine. Morphine, with a C-3 hydroxyl group, showed higher cytotoxicity and O2- scavenging activity than codeine, in which the hydroxyl group at C-3 was replaced with a methoxy group, suggesting the involvement of a radical-mediated reaction. The present report may offer new strategies for treatment and prevention of cancer using a clinical concentration of morphine not only as an anti-nociceptive, but also as an apoptosis or necrosis inducer.

DEC-205-mediated internalization of HIV-1 results in the establishment of silent infection in renal tubular cells.

HIV-1 infection of renal cells has been proposed to play a role in HIV-1-associated nephropathy. Renal biopsy data further suggest that renal tubular cells may serve as reservoir for HIV-1. The mechanism by which HIV-1 enters these cells has not been identified. Renal tubular cells do not express any of the known HIV-1 receptors, and our results confirmed lack of the expression of CD4, CCR5, CXCR4, DC-SIGN, or mannose receptors in tubular cells. The aim of this study, therefore, was to determine the mechanism that enables viral entry into renal tubular cells. An in vitro model was used to study the HIV-1 infection of human kidney tubular (HK2) cells and to identify the receptor that enables the virus to enter these cells. Results of these studies demonstrate that the C-type lectin DEC-205 acts as an HIV-1 receptor in HK2 cells. Interaction of HIV-1 with DEC-205 results in the internalization of the virus and establishment of a nonproductive infection. HIV-1-specific strong-stop DNA is detected in the infected HK2 cells for at least 7 d, and the virus can be transmitted in trans to sensitive target cells. HIV-1 entry is blocked by pretreatment with specific anti-DEC-205 antibody. Moreover, expression of DEC-205 in cells that lack the DEC-205 receptors renders them susceptible to HIV-1 infection. These findings suggest that DEC-205 acts as an HIV-1 receptor that mediates internalization of the virus into renal tubular cells, from which the virus can be rescued and disseminated by encountering immune cells.

Morphine reciprocally regulates IL-10 and IL-12 production by monocyte-derived human dendritic cells and enhances T cell activation.

We evaluated the effect of morphine on human dendritic cells (DCs). Interestingly, immature DCs were found to express all 3 (mu, kappa, delta) opioid receptors on the cell surface. Chronic morphine treatment (10(-8) to 10(-12) M) during the development of DCs from monocytes augmented LPS-induced upregulation of HLA-DR, CD86, CD80, and CD83 and increased the T cell stimulatory capacity of DCs, which could be inhibited by naloxone, an opioid receptor antagonist. The change in surface phenotype was paralleled by a p38 MAPK-dependent decrease in IL-10 and increase in IL-12 secretion. Our data indicate that morphine exerts an immunostimulatory effect by modulating LPS-induced DC maturation.

Induction of early apoptosis marker by morphine in human lung and breast carcinoma cell lines.

We have investigated whether morphine and codeine, potent analgesic compounds most commonly used as cancer pain relievers, show tumor-specific cytotoxic activity and whether they can induce apoptosis or necrosis by monitoring the stainability with Annexin V and propidium iodide with fluorescence-activated cell sorter. Both opioids showed higher cytotoxic activity against three human tumor cell lines (lung carcinoma A549, mammary gland carcinoma MCF7, promyelocytic leukemia HL-60) than against three normal human cells (periodontal ligament fibroblast HPLF, gingival fibroblast HGF, pulp cell HPC). Morphine produced the major part of the apoptotic cell populations and the minor part of the necrotic cell populations in A549 and MCF7 cells, more effectively than codeine. In addition, morphine increased the activity of mitochondrial Mn-containing superoxide dismutase (MnSOD) in HL-60 cells, but decreased the MnSOD activity in A549 and MCF7 cells. The apoptosis-inducing activity of opioids may provide new strategies for the treatment and prevention of cancer.

[Propofol depresses the activity of hypoglossal nerve more than that of phrenic nerve in rabbits].

BACKGROUND: Respiratory depression, such as obstruction of upper airway and inadequate ventilation, often appears during sedation and anesthesia. We studied the effect of propofol on the upper airway patency and the inspiratory drives. METHODS: Experiments were performed on the adult rabbits vagotomized, paralyzed and ventilated with nitrous oxide-oxygen-sevoflurane. We evaluated and compared depressant effect of propofol on the peak amplitude of both hypoglossal nerve (AMP-HG) and phrenic nerve (AMP-PH) activities, inspiratory time (Ti), expiratory time (Te) and respiratory cycle (Tc). RESULTS: Bolus injections of propofol transiently reduced AMP-HG more than AMP-PH (18 and 70% of control, respectively). But AMPs returned to the control levels about 10-15 min after the injection. For 0.5 mg.kg-1.min-1 continuous infusion, propofol soon began to reduce both AMPs. AMP-HG was reduced to about 20% and AMP-PH to 60% of control. Administration of propofol with 1.0 mg.kg-1.min-1 caused more reduction in AMPs with respiratory slowing and AMP-HG disappeared in some animals. CONCLUSION: During the sedation with low dose of propofol, we need to pay attention to potential upper airway obstruction. In addition to the above, high doses of propofol could reduce spontaneous inspiratory drive, and we need to keep both upper airway patency and sufficient ventilation.

Comparative analysis of apoptosis-inducing activity of codeine and codeinone.

BACKGROUND: There are relatively few studies about the antiproliferative effects of codeine-related compounds on human cancer cell lines, compared with those of morphine-related compounds. The authors previously found that codeinone, an oxidation metabolite of codeine, among 10 opioids, showed the highest cytotoxic activity (DNA fragmentation-inducing activity) against human promyelocytic leukemic cell lines (HL-60). This was counteracted by an antioxidant, N-acetyl-L-cysteine (NAC). These findings prompted us to perform a more detailed study of apoptosis induction after codeinone treatment. METHODS: Apoptosis was induced by treating HL-60 cells for 1-6 h with codeine or codeinone. DNA fragmentation was assessed by both agarose gel electrophoresis and fluorometric determination of the fragmented DNA after staining with diamidinophenylindole (DAPI). The appearance of apoptotic cells was monitored by microscopic observation after staining with Hoechst (H)-33342, and fluorescence activated cell sorter (FACS) after staining with Annexin. The release of cytochrome c and cytochrome oxidase from mitochondria and activation of caspase 3 were monitored by Western blot analysis. Intracellular caspase 3-like activity was confirmed by FACS, using cell permeable substrate. Mitochondrial manganese-containing superoxide dismutase (MnSOD) activity and mRNA expression were assayed by activity staining after separation on the polyacrylamide gel electrophoresis, and reverse transcriptase-polymerase chain reaction (RT-PCR), respectively. RESULTS: Codeinone induced internucleosomal DNA fragmentation and production of Annexin-positive apoptotic cells more potently than codeine in HL-60 cells. Codeinone stimulated the release of both cytochrome c and cytochrome oxidase, and cleavage of procaspase 3 without significant changes in both the activity and expression of MnSOD. CONCLUSIONS: Codeinone was found to possess both apoptosis and necrosis-inducing activity, in addition to the reported antinociceptive activity, further substantiating its antitumor potential.

Induction of cell death by pro-oxidant action of Moxa smoke.

Moxa smoke induced internucleosomal DNA fragmentation in human promyelocytic leukemic HL-60 cells, but not in other cell lines. The cytotoxic activity of Moxa smoke was significantly reduced by a popular antioxidant, N-acetyl-L-cysteine (NAC). Moxa smoke showed oxidation potential (measured by NO monitor) and produced carbon radical (measured by ESR spectroscopy). The addition of NAC significantly reduced both the oxidation potential and carbon radical intensity of Moxa smoke. Activity staining of polyacryamide gel electrophoresis of MnSOD revealed the possible modification of the conformation and/or activity of this enzyme at an early stage of HL-60 cell death. These data suggest that Moxa smoke induces cytotoxicity by its pro-oxidant action.

Partial purification of cytotoxic substances from moxa extract.

The major cytotoxic activity of Moxa was extracted with CH2Cl2 and partially purified by three cycles of silica gel column chromatography. The active fractions showed higher cytotoxicity against six human tumor cell lines (two oral squamous cell carcinoma, one salivary gland tumor, one melanoma, two leukemia) than three normal oral human cells (gingival fibroblast, periodontal ligament fibroblast, pulp cell). All fractions failed to protect the cells from the cytopathic effect induced by HIV infection. ESR spectroscopy showed that all fractions produced little or no radical under alkaline conditions, while showing much lower O2- scavenging activity, generated by hypoxanthine-xanthine oxidase reaction, than antioxidants and polyphenols. Active fractions induced DNA fragmentation in HL-60 cells, but failed to modify the mobility and activity of mitochondrial Mn-containing superoxide dismutase (MnSOD), in contrast to Moxa smoke. These data suggest that the active principles in the Moxa extract might be different from that in Moxa smoke, which produced carbon radical and modified MnSOD mobility and activity.