방사선 조사가 백서 피부 Fibroblast의 Collagen 합성에 미치는 영향 = EFFECTS OF RADIATION ON COLLAGEN SYNTHESIS IN CULTURED FIBROBLASTS OF RAT SKIN

다국어 초록 (Multilingual Abstract)

Keloids are predominantly fibrous sKin tumors that take the form, variable pruritic or tender growth near the site of an injury. Histopathologically, they are rich in various connective tissue components such as collagen. The exact mechanism of keloid formation is at pressure, local injection of syntheic steroids and radiation are now clinically used in the therapy of these lesions. Although radiation is widely used in keloid treatment at present, its mechanism is unknown at the molecular level.
In the present study, cultured fibroblasts of rat skin were treated with various radiation doses and the cell grouth and the amounts of collagen and collagen mRNA were measured. Fibroblasts were isolated and cultured from 2-day-old rat skin, and the subcultured cells were irradiated with 300rads at 24hour intervals(one time with 300 rads, 2 times for a total of 600 rads, and 3 times for a total of 900 rads)from 24 hours after the subculture.
The thymidine incoration in the culture flasks treated with 300, 600, and 900 rads was 54.6, 29.0, and 23.9% of the control at 2 hours, and 59.8, 40.1, and 34.6% at 8 hours respectively, indicating that radiation severely ingibits the cell growth.
The effects of radiation on the amount of collagen were examined by measuring the hydroxyproline, which is a specific amino acid in collagen. The amounts of hydroxyproline in the 300 and 600 rad radiation groups were decreased to 44.2 and 33.3% of that of the control group, and that of the 900 rad radiation group could not be detected. To discriminate whether-these decreases in collagen content by radiation were due only to inhibition of cell growth or whether the radiation had a selective inhibitory effect on collagen content by radiation were due only to inhibition of cell growth or whether the radiation had a selective inhibitory effect on collagen synthesis, we counted the radioactivities of the peptide released by collagenase with the quantitation of DNA. The newly synthesized total protein if the 300, 600 and 900 rad radiation groups was decreased to 66.8, 48.2 and 40.3% of that the control group, respectively, but the total protein per ㎍ DNA was increased to 137.2, 132.3 and 109.7% respectively. The amounts of newly synthesized collagen were also decreased to 66.2, 50.2 and 40.1% of that of the control, but the amount of collagen per ㎍ DNA was increased to 136.1, 138.5 and 40.1% of that of the control, but the amount of collagen per ㎍ DNA was increased to 136.1, 138.5 and 109.3%, respectively, which was a similar pattern to the observed changes of total protein. the radiation did not inhibit the transcription of collagen α1(I)mRAN, according to the result of RAN dot hybridization.
These results indicate that radiation has no selective inhibitory effect on collagen synthesis and the decrease of collagen amounts by radiation is due only to its inhibition of cell growth.