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Biomedical subjects

W A Matthews

Publications and source records attributed to W A Matthews.

10 recordsLinked to original sources
PubMed1996

Inhibition of hamster mesothelioma tumorigenesis by an antisense expression plasmid to the insulin-like growth factor-1 receptor.

We evaluated the effect of antisense insulin-like growth factor (IGF) receptor transcripts on the proliferation and tumorigenicity in an SV40-induced, immunocompetent hamster mesothelioma model (H9A). Expression of IGF-1 and IGF-1 receptor (IGF-1R) genes was identified from H9A RNA using reverse transcription-PCR and Northern analysis. H9A cells were electroporated with inducible expression vectors (under the transcriptional control of heat shock promoter HSP70) containing a cDNA fragment corresponding to base pairs 1-309 of IGF-1R in the sense or antisense orientation to generate the respective clones A3 sense or B9 antisense. The expression vector in genomic DNA was detected with PCR analysis as a 173-bp fragment on ethidium bromide gels. The effects of the expression vectors were then evaluated in vitro under active (at 39 degrees C) or inactive (at 34 degrees C) conditions. At 39 degrees C, the B9 antisense transfectants demonstrated significantly less proliferation than A3 sense transfectants (P2 < 0.02). At 34 degrees C, cell growth of A3 sense- and B9 antisense-transfected cells was not significantly different. In vivo tumorigenicity was evaluated in hamsters inoculated with 10(5) A3 sense- or B9 antisense-transfected cells. The A3 sense clones resulted in greater numbers of tumors in vivo compared to the B9 antisense clone (P2 = 0.0001). When genomic DNA from tumors that developed in A3 sense and B9 antisense animals was analyzed for the expression vectors, a 173-bp fragment amplified from the expression vector was identified in the sense tumors but not in antisense B9 or wild-type H9A tumors, indicating a loss of the vector from the antisense clones that proliferated in vivo. The inhibitory effect of IGF-1R antisense transcripts on hamster mesothelioma demonstrated in this study by decreased growth and tumorigenicity in vitro and in vivo may have implications for the therapy of human mesothelioma.

Animals↗
PubMed1991

Photodynamic therapy of oncogene-transformed cells.

Photodynamic therapy with dihematoporphyrin ether sensitizes malignant cells to damage by 630 nm light. The in vitro, in vivo photodynamic therapy sensitivity of a cell line transformed by the Kirsten ras oncogene (45342) was studied to establish a new photodynamic therapy model. With the colony formation assay, neither light alone nor dihematoporphyrin ether alone affected 45342 survival. Energy-dependent photodynamic therapy effects were seen in vitro in dihematoporphyrin ether-incubated and light-exposed cells (90% cytotoxicity = 950 joules/m2; 99% cytotoxicity = 1575 joules/m2; p2 less than 0.05). Subcutaneous allografts of 45342 were established in nu/nu mice, and ideal route (intravenous or intraperitoneal) of dihematoporphyrin ether delivery, dihematoporphyrin ether tissue kinetics, and in vivo photodynamic therapy effects were examined. Intravenous administration not only gave higher levels of the sensitizer in various tissues, but also was associated with less variation than the intraperitoneal route. Selective dihematoporphyrin ether retention was documented in the tumors at 24 hours after injection compared with other tissues, and photodynamic therapy with 0.3 W/cm2 to a total dose of 150 joules/cm2 led to progressive coagulative tumor necrosis and tumor regression. These studies confirm that transformed, malignant cells are sensitive to photodynamic therapy, and this model may prove in future studies to increase efficacy to photodynamic therapy (i.e., with dihematoporphyrin ether delivery by monoclonal antibodies).

Animals↗
PubMed1991

Tumor necrosis factor-alpha alters response of lung cancer cells to oxidative stress.

Selected immunotherapies (tumor necrosis factor, interleukin-1, interleukin-2, and gamma interferon), chemotherapeutic agents (mitomycin, platinum, doxorubicin [Adriamycin], and bleomycin), and radiation therapy have been described to exert cytotoxicity through the generation of reactive oxygen species, including superoxide and hydrogen peroxide. Tumor necrosis factor, however, has been shown to impart increased resistance in vitro and in vivo against reactive oxygen species stress, including radiation therapy and oxygen toxicity, possibly because of the induction of increased cellular buffering capacities. It is unknown whether the sensitivity of a lung cancer cell to reactive oxygen species therapy is altered by tumor necrosis factor through the induction of free radical scavenging enzymes such as manganese superoxide dismutase. This question was investigated as follows: A549 lung adenocarcinoma cells, exposed for 24 hours to 0, 0.1, 1.0, or 10 micrograms/ml concentrations of tumor necrosis factor, were exposed to hypoxanthine plus xanthine oxidase, a superoxide generating system, for varying intervals. The number of cells surviving 5 days after the stress was determined, and cells exposed to tumor necrosis factor were examined by Northern Blot analysis for induction of the manganese superoxide dismutase gene. The hypoxanthine-xanthine oxidase stress alone caused a time-dependent decrease in survival; however, pretreatment with tumor necrosis factor increased cell survival significantly. Moreover, the cells exposed to tumor necrosis factor had a fivefold increase in the number of manganese superoxide dismutase transcripts. These findings suggest that tumor necrosis factor may confer resistance of lung cancer cells to subsequent reactive oxygen species-based therapies, and the resistance of these cells may be due to increased expression of manganese superoxide dismutase. Clinical treatment failures may result, especially if tumor necrosis factor is given concurrently with other therapies.

Adenocarcinoma↗