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KMID : 0362919940120030271
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Journal of the Korean Society for Therapeutic Radiology and Oncology
1994 Volume.12 No. 3 p.271 ~ p.284
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The Influence of 5-Fluorouracil Administration Mode on the Expression of Phospholipase C and Ras Oncoprotein Associated with Regeneration of Rat Intestinal Mucosa Following Radiation
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Park Kyung-Ran
Rhee Chung-Sik
Kim Sung-Sook
Lee Young-Han
Ryu Sung-Ho
Suh Pan-Ghil
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Abstract
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Purpose: Phospholipase C (PLC) isozymes ply significant roles in transmembrane signal transduction. PLC-¡ 1 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.
Materials and Methods: To determine the effect of the administration 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. GroupⅠhad no treatment. GroupⅡ received radiation( 8 Gy) only. Group Ⅲ received radiation(8 Gy) and 5-FU(150mg/kg) continuous intravenous (iv) infusion for 12 hours. Group iv bolus injection. Group Ⅴ received only 5-FU(150mg/kg) iv bolus injection. Through immunoblotting and immunohistochemistry, we examined 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 administration. We also investigated the histological findings using hematoxylin and eosin stain.
Results: In the immunohistochemistry study, PLC-¡ 1 expression was the highest in group Ⅲ followed by groups Ⅱ and Ⅵ in that order and was weakly positive in groups Ⅴ and Ⅵ. PLC-¡ 1 was hardly detected in the control group. The expression of ras oncoprotein wss the same as the PLC-¡ 1 expression for all groups. These results were confirmed by the histological findings regarding the mucosal regeneration. In the immunoblotting analysis, PLC-¡ 1 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-¡ 1 on the damaged surface epithelium rather than to its expression in the regeneration region as observed in the immunohistochemistry study for group Ⅳ. The expression of PLC- 1 was positive only in group Ⅴ and Ⅵ, which received both radiation and 5-FU, and the expression of PLC-b 1was negligible for all groups.
Conclusion: These results suggest that PLC-¡ 1 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- 1 in combined group of radiation and 5-FU implies that PLC- 1 may be involved in signal transduction mediated by concerted action between radiation and 5-FU.
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KEYWORD
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Radiotherapy-5-fluorouracil interaction, Jejunal crypt cell, Phospholipase C, Ras oncoprotein
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