THE EFFECT OF IONIZING RADIATION ON THE PROSTAGLANDIN CONCENTRATION OF MOUSE MAMMARY TUMORS AS MEASURED BY RADIOIMMUNOASSAY
Abstract
Many types of tumors, including mammary carcinomas, have been shown to have elevated prostaglandin levels compared to normal tissue. As irradiation is a widely used form of cancer treatment, and since the effects of irradiation on only normal tissue prostaglandin levels have been reported in the literature, this study was undertaken for the purpose of examining the effects of x-ray treatment on C3HeB/FeJ mouse mammary tumor prostaglandin levels. Tumors were induced by transplantation of an originally spontaneous mammary carcinoma. Non-irradiated mammary tumors served as controls. X rays were generated by a General Electric Maxitron 300 therapy unit. Tumors irradiated by dose regimens I and II received approximately 4250 rad in three and five fractions, respectively. Dose regimen III consisted of five fractions resulting in a total dose of 2850 rad. All fractions were given at 48 h intervals. Prostaglandin concentrations in the tumors were measured with a commercially available Prostaglandin E radioimmunoassay kit when the mice were killed on the third, sixth, or twelfth day following the final irradiation. Tumor prostaglandin concentrations were compared to determine whether there were any differences among the three irradiation regimens and the control tumors. Analyses of possible dose rate as well as total dose effects were performed. In all of the analyses, the only significant factor was time of killing following irradiation. For tumors subjected to dose regimens I and III, tumor prostaglandin levels were elevated above control tumor levels at Day 3. At Day 6, the irradiated tumor prostaglandin levels were at a low value, and were now less than control levels. There was a slight increase in prostaglandin level at Day 12, but the level was still below that of the controls. For the dose regimen II tumors, the irradiated vs. control prostaglandin levels were the opposite of those found with regimens I and III. Irradiated tumor levels were only 90% of the control levels at Day 3, and at Day 6 the irradiated tumor levels were slightly higher than controls.
Degree
Ph.D.
Subject Area
Radiology
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