Induction of apoptosis by a stilbene analog involves Bax translocation regulated by p38 MAPK and Akt

Mitogen-activated protein kinase-activated protein kinase 2 mediates apoptosis during lung vascular permeability by regulating movement of cleaved caspase 3

Apoptosis is a key pathologic feature in acute lung injury. Animal studies have demonstrated that pathways regulating apoptosis are necessary in the development of acute lung injury, and that activation of p38 mitogen-activated protein kinase (MAPK) is linked to the initiation of the apoptotic cascade. In this study, we assessed the role of the MAPK-activated protein kinase (MK) 2, one of p38 MAPK's immediate downstream effectors, in the development of apoptosis in an animal model of LPS-induced pulmonary vascular permeability. Our results indicate that wild-type (WT) mice exposed to LPS demonstrate increased apoptosis, as evidenced by cleavage of caspase 3 and poly (ADP-ribose) polymerase 1 and increased deoxynucleotidyl transferase-mediated dUDP nick-end labeling staining, which is accompanied by increases in markers of vascular permeability. In contrast, MK2(-/-) mice are protected from pulmonary vascular permeability and apoptosis in response to LPS. Although there was no difference in activation of caspase 3 in MK2(-/-) compared with WT mice, interestingly, cleaved caspase 3 translocated to the nucleus in WT mice while it remained in the cytosol of MK2(-/-) mice in response to LPS. In separate experiments, LPS-induced apoptosis in human lung microvascular endothelial cells was also associated with nuclear translocation of cleaved caspase 3 and apoptosis, which were both prevented by MK2 silencing. In conclusion, our data suggest that MK2 plays a critical role in the development of apoptosis and pulmonary vascular permeability, and its effects on apoptosis are in part related to its ability to regulate nuclear translocation of cleaved caspase 3.

Expression of CYP1A1, CYP1B1 and MnSOD in a panel of human cancer cell lines

The expression of P450 enzymes and antioxidative enzymes in tumour tissue can have a major impact on the responsiveness of tumours to cancer chemotherapeutic drugs, therefore such information may be very precious when experiments are designed. The compressive information, concerning the expression of drug metabolism enzymes or antioxidative enzymes is still lacking, therefore in this study the expression of CYP1A1, CYP1B1 and mitochondrial superoxide dismutase MnSOD (both mRNA and protein) in a panel of eight commonly used cancer cell lines, representing four tumour tissues was assayed. In the study two ovarian cancer cell lines A2780 and SKOV-3, two colorectal cancer LOVO and DLD-1, two breast cancer derived MCF-7 and MDA-MB-231 and two cervical cancer cell lines HeLa and C33A were employed. The relatively high expression of all assayed enzymes was shown in MDA-MB-231 breast cancer cells, lack of cancer cell specific CYP1B1 protein was discovered in LOVO colorectal cells. In order to test possible correlation between expression of CYP1A1, CYP1B1 and MnSOD and modulators of their activity, cytotoxicity of resveratrol and its promising hydroxylated analogue 3,3′,4,4′,5,5′-trans-hexahydroxystilbene against cell lines used in experiment was assayed. The relatively high correlation was found between IC₅₀ values calculated for 3,3′,4,4′,5,5′-trans-hexahydroxystilbene and expression of MnSOD (r = 0.6562).

Apocynin attenuates ventilator-induced lung injury in an isolated and perfused rat lung model

RATIONALE

Apocynin suppresses the generation of reactive oxygen species (ROS) that are implicated in ventilator-induced lung injury (VILI). We thus hypothesized that apocynin attenuates VILI.

METHODS

VILI was induced by mechanical ventilation with tidal volume (V(t)) of 15 ml/kg in isolated and perfused rat lung. Apocynin was administered in the perfusate at onset of mechanical ventilation. A group ventilated with low V(t) of 5 ml/kg served as control. Hemodynamics, lung injury indices, inflammatory responses, and activation of apoptotic pathways were determined upon completion of mechanical ventilation.

RESULTS

There was an increase in lung permeability and lung weight gain after mechanical ventilation with high V(t), compared with low V (t). Levels of inflammatory cytokines including interleukin-1β (IL-1β), tumor necrosis factor-alpha (TNF-α), and macrophage inflammatory protein-2 (MIP-2) increased in lung lavage fluids; concentrations of carbonyl, thiobarbituric acid reactive substances, and H(2)O(2) were higher in perfusates and lung lavage fluids, and expression of myeloperoxidase, JNK, p38, and caspase-3 in lung tissue was greater in the high-V(t) than in the low-V(t) group. Administration of apocynin attenuated these inflammatory responses and lung permeability associated with decreased activation of nuclear factor-κB.

CONCLUSIONS

VILI is associated with inflammatory responses including generation of ROS, cytokines, and activation of mitogen-activated protein kinase cascades. Administration of apocynin at onset of mechanical ventilation attenuates inflammatory responses and VILI in the isolated, perfused rat lung model.

Activation-induced cell death and total Akt content of granulocytes show a biphasic course after low-dose radiation

Low-dose radiation (single doses from 0.3 to 1.0 Gy) in clinical practice is mostly used to treat patients with several inflammatory diseases and painful degenerative disorders. Low-dose radiation is known to exert anti-inflammatory effects. However, the molecular and cellular mechanism are not fully analysed and most of the observed effects are based on empirical studies. We investigated the effects of low-dose radiation on the activation-induced cell death of polymorph nuclear granulocytes (PMN). A biphasic appearance of cell death in irradiated PMN was observed, displaying a relative maximum at 0.3 Gy and minimum at 0.5 Gy, respectively. This biphasic course of cell death was coincident with the protein level of total cellular Akt. We conclude that low-dose radiation exerts immunomodulatory effects on PMN contributing to the observed anti-inflammatory effects in clinical applications.

Alveolar cell apoptosis is dependent on p38 MAP kinase-mediated activation of xanthine oxidoreductase in ventilator-induced lung injury

Signaling via p38 MAP kinase has been implicated in the mechanotransduction associated with mechanical stress and ventilator-induced lung injury (VILI). However, the critical downstream mediators of alveolar injury remain incompletely defined. We provide evidence that high-tidal volume mechanical ventilation (HVt MV) rapidly activates caspases within the lung, resulting in increased alveolar cell apoptosis. Antagonism of MV-induced p38 MAP kinase activity with SB-203580 suppresses both MV-induced caspase activity and alveolar apoptosis, placing p38 MAP kinase upstream of MV-induced caspase activation and programmed cell death. The reactive oxygen species (ROS)-producing enzyme xanthine oxidoreductase (XOR) is activated in a p38 MAP kinase-dependent manner following HVt MV. Allopurinol, a XOR inhibitor, also suppresses HVt MV-induced apoptosis, implicating HVt MV-induced ROS in the induction of alveolar cell apoptosis. Finally, systemic administration of the pan-caspase inhibitor, z-VAD-fmk, but not its inactive peptidyl analog, z-FA-fmk, blocks ventilator-induced apoptosis of alveolar cells and alveolar-capillary leak, indicating that caspase-dependent cell death is necessary for VILI-associated barrier dysfunction in vivo.