Biomedical subjects

John I Johnsen

Publications and source records attributed to John I Johnsen.

3 recordsLinked to original sources

PubMed2005

NSAIDs in neuroblastoma therapy.

Cyclooxygenases (COX) catalyse the conversion of arachidonic acid to prostaglandins. COX-2 is upregulated in several adult epithelial cancers. In neuroblastoma it has been shown that the majority of primary tumours and cell lines express high levels of COX-2, whereas normal adrenal medullas from children do not express COX-2. Treatment of neuroblastoma cells with nonsteroidal anti-inflammatory drugs (NSAIDs), inhibitors of COX, induces caspase-dependent apoptosis via the intrinsic mitochondrial pathway. Established neuroblastoma xenografts in nude rats treated with the dual COX-1/COX-2 inhibitor, diclofenac, or the COX-2 specific inhibitor, celecoxib significantly inhibits neuroblastoma growth in vivo. In vitro, arachidonic acid and diclofenac synergistically induces neuroblastoma cell death. This effect is further pronounced when lipoxygenases is inhibited simultaneously. Proton MR-spectroscopy (1H MRS) of neuroblastoma cells treated with COX-inhibitors demonstrates accumulation of polyunsaturated fatty acids and depletion of choline compounds. Thus, 1H MRS, which can be performed with clinical MR-scanners, is likely to provide pharmacodynamic markers of neuroblastoma response to COX-inhibition. Taken together, these data suggest the use of NSAIDs as a novel adjuvant therapy for children with neuroblastoma.

Animals↗

PubMed2004

Cyclooxygenase-2 is expressed in neuroblastoma, and nonsteroidal anti-inflammatory drugs induce apoptosis and inhibit tumor growth in vivo.

Neuroblastoma is the single most common and deadly tumor of childhood and is often associated with therapy resistance. Cyclooxygenases (COXs) catalyze the conversion of arachidonic acid to prostaglandins. COX-2 is up-regulated in several adult epithelial cancers and is linked to proliferation and resistance to apoptosis. We detected COX-2 expression in neuroblastoma primary tumors and cell lines but not in normal adrenal medullas from children. Treatment of neuroblastoma cells with nonsteroidal anti-inflammatory drugs, inhibitors of COX, induced caspase-dependent apoptosis via the intrinsic mitochondrial pathway. Treatment of established neuroblastoma xenografts in nude rats with the dual COX-1/COX-2 inhibitor diclofenac or the COX-2-specific inhibitor celecoxib significantly inhibited tumor growth in vivo (P < 0.001). In vitro, arachidonic acid and diclofenac synergistically induced neuroblastoma cell death. This effect was further pronounced when lipooxygenases were simultaneously inhibited. Proton magnetic resonance spectroscopy ((1)H MRS) of neuroblastoma cells treated with COX inhibitors demonstrated accumulation of polyunsaturated fatty acids and depletion of choline compounds. Thus, (1)H MRS, which can be performed with clinical magnetic resonance scanners, is likely to provide pharmacodynamic markers of neuroblastoma response to COX inhibition. Taken together, these data suggest the use of nonsteroidal anti-inflammatory drugs as a novel adjuvant therapy for children with neuroblastoma.

Adrenal Gland Neoplasms↗

PubMed2004

Synergistic induction of apoptosis in neuroblastoma cells using a combination of cytostatic drugs with interferon-gamma and TRAIL.

The majority of high-risk neuroblastomas lack the expression of caspase-8 due to gene silencing which suggest a mechanism for the selection of tumour cells that are refractory to multiple cytotoxic drugs including tumour necrosis factor-related apoptosis-inducing ligand (TRAIL). Inhibitors of DNA methyltransferases and IFN-gamma induce expression of caspase-8, and sensitise some neuroblastoma cells to TRAIL-mediated apoptosis. Here we demonstrate that a combination of cytostatic drugs with IFN-gamma and TRAIL synergistically induces neuroblastoma cell death, which may have implications for future therapy of children with neuroblastoma. Treatment of neuroblastoma cells with IFN-gamma induced caspase-8 expression in all cell lines investigated. In five of the neuroblastoma cell lines (SHEP-1, SK-N-AS, SK-N-FI, SH-SY-5Y and Kelly), IFN-gamma promoted TRAIL-mediated cleavage of caspase-8, initiating a caspase cascade involving caspase-7 and PARP followed by apoptosis. IFN-gamma-mediated facilitation of apoptosis was inhibited by the pan-caspase inhibitor zVAD-fmk and the caspase-8 specific inhibitor zIEDT-fmk, indicating an important role of caspase-8 in mediating sensitation by IFN-gamma in neuroblastoma cells. In three of the cell lines [SK-N-BE(2), SK-N-DZ and IMR-32] caspase-8 expression was induced by IFN-gamma, but the cells were still resistant to TRAIL-mediated apoptosis. The pattern of basal TRAIL receptor expression, decoy receptors, FLIP and FADD could not be correlated with resistance or sensitivity to TRAIL-induced apoptosis. Importantly, treatment of neuroblastoma cell lines with cytostatic drugs increased apoptosis in the TRAIL-sensitive cell lines whereas the resistant cell lines were susceptible to TRAIL-mediated apoptosis in the presence of the anticancer drugs. The mechanism of the increased susceptibility to apoptosis might results from drug-mediated up-regulation of the death receptors DR4 and DR5.

Antineoplastic Agents↗