방사선 조사 후 백서 공장 점막의 재생과정에서 5-fluorouracil 투여가 phospholipase C 와 ras 암유전자단백의 발현에 미치는 영향

The influence of 5-Fluorouracil Administration Mode on the Expression of Phospholipase C and Ras Oncoprotein Associated with Regeneraiton of Rat Intestinal Mucosa Following Radiation

Purpose : Phospholipase C(PLC) isozymes play significant roles in transmembranesignal transduction. PLC-γ1 acts as the intracellular effector in signal transduction for cellular proliferation and differentiation. Ras oncoprotein is also involved in cell growth. We determined the biological significance of PLC and ras oncoprotein in regeneration following radiation and the effect of different modes of administration of 5-FU Meterials and Methods : To determine the effect of the administrations mode of 5-FU on the regeneration of intestinal mucosa of rats following radiation, we compared the expression of PLC and ras oncoprotein in six groups. Group Ⅰ had no treatment. Group Ⅱ received radiation(8 Gy) only. Group Ⅲ received radiation(8Gy) and 5-FU(150mg/kg) continuous intravenous (ⅳ) infusion for 12 hours. Group Ⅳ received radiation(8Gy) and 5-FU(150mg/kg) ⅳbolus injection. Group Ⅴ received only 5-FU(150mg/kg) continuous ⅳ infusion for 12 hours. Group Ⅵ received only 5-FU(150mg/kg) ⅳ bolus injection. Through immunoblotting and immumohistochemistry, we exmained the expression of PLC and ras oncoprotein in rat jejunum at 96 hours after radiation or 5-FU administration and at 120 hours after radiation and 5-FU adminstration. We also investigated the histological findings using hematoxyling and eosin stain. Results : In the immumohistochemistry study, PLC-γ1 expression was the highest in group Ⅲ followed by groups Ⅱ and Ⅳ in that order and was weakly positive in groups Ⅴ and Ⅵ. PLC-γ1 was hardly detected in the control group. The expression of ras oncoprotein was the same as the PLC-γ1 expression for all groups. These results were confirmed by the histological findings regarding the mucosal regeneration. In the immunoblotting analysis, PLC-γ1 expression was the highest in group Ⅲ followed by group Ⅳ and Ⅱ in that order. This difference between the immunoblotting and immunohistochemistry study was due to the high expression of PLC-γ1 on the damaged surface epithelium rather than to its expression in the regeneration region as obsrved in the immunohistochemistry study for group Ⅳ. The expression of PLC-γ1 was positive only in group Ⅴ and Ⅵ, which received both radiation and 5-FU and the expression of PLC-β1 was negligible for all groups. Conclusion : These results suggest that PLC-γ1 mediated signal transduction and ras oncoprotein may have a significant role in mucosal regeneration after radiation, and that continuous ⅳ infusion of 5-FU may induce active regeneration in intestinal mucosa following radiation. In addition the expression of PLC-δ1 in combined group of radiation and 5-FU implies that PLC-δ1 may be involved in signal transduction mediated by concerted action between radiation and 5-FU.