Morphine inhibits doxorubicin-induced reactive oxygen species generation and nuclear factor kappaB transcriptional activation in neuroblastoma SH-SY5Y cells.
ABSTRACT Morphine is recommended as a first-line opioid analgesic in the pain management of cancer patients. Accumulating evidence shows that morphine has anti-apoptotic activity, but its impact on the therapeutic applications of antineoplastic drugs is not well known. The present study was undertaken to test the hypothesis that morphine might antagonize the pro-apoptotic activity of DOX (doxorubicin), a commonly used antitumour drug for the treatment of neuroblastoma, in cultured SH-SY5Y cells. In the present study we demonstrated that morphine suppressed DOX-induced inhibition of cell proliferation and programmed cell death in a concentration-dependent, and naloxone as well as pertussis toxin-irreversible, manner. Further studies showed that morphine inhibited ROS (reactive oxygen species) generation, and prevented DOX-mediated caspase-3 activation, cytochrome c release and changes of Bax and Bcl-2 protein expression. The antioxidant NAC (N-acetylcysteine) also showed the same effects as morphine on DOX-induced ROS generation, caspase-3 activation and cytochrome c release and changes in Bax (Bcl-2-associated X protein) and Bcl-2 protein expression. Additionally, morphine was found to suppress DOX-induced NF-kappaB (nuclear factor kappaB) transcriptional activation via a reduction of IkappaBalpha (inhibitor of nuclear factor kappaB) degradation. These present findings support the hypothesis that morphine can inhibit DOX-induced neuroblastoma cell apoptosis by the inhibition of ROS generation and mitochondrial cytochrome c release, as well as by blockade of NF-kappaB transcriptional activation, and suggests that morphine might have an impact on the antitumour efficiency of DOX.
Article: Implication of radical oxygen species in ceramide generation, c-Jun N-terminal kinase activation and apoptosis induced by daunorubicin.[show abstract] [hide abstract]
ABSTRACT: Anthracyclines such as daunorubicin (DNR) generate radical oxygen species (ROS), which account, at least in part, for their cytotoxic effect. We observed that early ceramide generation (within 6-10 min) through neutral sphingomyelinase stimulation was inhibitable by the antioxidants N-acetylcysteine and pyrrolidine dithiocarbamate, which led to a decrease in apoptosis (>95% decrease in DNA fragmentation after 6 h). Furthermore, we observed that DNR triggers the c-Jun N-terminal kinase (JNK) and the transcription factor activated protein-1 through an antioxidant-inhibitable mechanism. Treatment of U937 cells with cell-permeant ceramides induced both an increase in ROS generation and JNK activation, and apoptosis, all of which were antioxidant-sensitive. In conclusion, DNR-triggered apoptosis implicates a ceramide-mediated, ROS-dependent JNK and activated protein-1 activation.Molecular Pharmacology 12/1999; 56(5):867-74. · 4.88 Impact Factor
Article: Evidence that activation of nuclear factor-kappaB is essential for the cytotoxic effects of doxorubicin and its analogues.[show abstract] [hide abstract]
ABSTRACT: Several reports within the last 5 years have suggested that nuclear factor (NF)-kappaB activation suppresses apoptosis through expression of anti-apoptotic genes. In the present report, we provide evidence from four independent lines that NF-kappaB activation is required for the cytotoxic effects of doxorubicin. We used doxorubicin and its structural analogues WP631 and WP744, to demonstrate that anthracyclines activate NF-kappaB, and this activation is essential for apoptosis in myeloid (KBM-5) and lymphoid (Jurkat) cells. All three anthracyclines had cytotoxic effects against KBM-5 cells; analogue WP744, was most potent, with an IC(50) of 0.5 microM, and doxorubicin was least active, with an IC(50) of 2 microM. We observed maximum NF-kappaB activation at 1 microM with WP744 and at 50 microM with doxorubicin and WP631, and this activation correlated with the IkappaBalpha degradation. Because the anthracycline analogue (WP744), most active as a cytotoxic agent, was also most active in inducing NF-kappaB activation and the latter preceded the cytotoxic effects, suggests that NF-kappaB activation may mediate cytotoxicity. Second, receptor-interacting protein-deficient cells, which did not respond to doxorubicin-induced NF-kappaB activation, were also protected from the cytotoxic effects of all the three anthracyclines. Third, suppression of NF-kappaB activation by pyrrolidine dithiocarbamate, also suppressed the cytotoxic effects of anthracyclines. Fourth, suppression of NF-kappaB activation by NEMO-binding domain peptide, also suppressed the cytotoxic effects of the drug. Overall our results clearly demonstrate that NF-kappaB activation and IkappaBalpha degradation are early events activated by doxorubicin and its analogues and that they play a critical pro-apoptotic role.Biochemical Pharmacology 02/2004; 67(2):353-64. · 4.70 Impact Factor
[show abstract] [hide abstract]
ABSTRACT: The tumour suppressor p53 inhibits cell growth through activation of cell-cycle arrest and apoptosis, and most cancers have either mutation within the p53 gene or defects in the ability to induce p53. Activation or re-introduction of p53 induces apoptosis in many tumour cells and may provide effective cancer therapy. One of the key proteins that modulates the apoptotic response is NF-kappaB, a transcription factor that can protect or contribute to apoptosis. Here we show that induction of p53 causes an activation of NF-kappaB that correlates with the ability of p53 to induce apoptosis. Inhibition or loss of NF-kappaB activity abrogated p53-induced apoptosis, indicating that NF-kappaB is essential in p53-mediated cell death. Activation of NF-kappaB by p53 was distinct from that mediated by tumour-necrosis factor-alpha and involved MEK1 and the activation of pp90rsk. Inhibition of MEK1 blocked activation of NF-kappaB by p53 and completely abrogated p53-induced cell death. We conclude that inhibition of NF-kappaB in tumours that retain wild-type p53 may diminish, rather than augment, a therapeutic response.Nature 05/2000; 404(6780):892-7. · 36.28 Impact Factor