| Summary: | 碩士 === 國立成功大學 === 生物化學研究所 === 92 === Ⅰ. Interleukin (IL)-13 is an important cytokine secreted from type 2 helper T lymphocytes and has been associated with asthma. Interleukin (IL)-19 belongs to the IL-10 family and little was known about the biologic function. Interleukin (IL)-21 is a new member of the type I cytokine superfamily and is a T helper (Th) cell 2 cytokine that specifically inhibits the differentiation of naive Th cells into interferon gamma-producing Th1 cells. In our previous studies, we explored IL-19 & IL-21 associated with pathogenesis of asthma, we employed ELISA to analyze the serum level of IL-19 & IL-21 in the asthma patients and found that IL-19 & IL-21 level in the patients was two-fold over the normal control. To investigate the regulation of IL-13 gene expression by IL-19 & IL-21 with activation of T cell in vitro. We constructed two plasmid DNA vectors which contained different length of IL-13 promoter (-1560 to +49,-940 to +49) upstream of luciferase reporter gene. We named these two constructs, pA and pB. These two plasmids were transfected into Jurkat T cell line. Jurkat T cells were used as a model to examine the requirements of T cell activation. Cell cultures were stimulated with PMA and ConA. The results of luciferase activity showed that pA region expressed higher promoter activity. Treatment of cells with IL-21 resulted in no significant effect of luciferase activity. IL-21 may induce IL-13 transcript on the activated T cells through enhancing mRNA stability or other factors. Further, we employed real-time PCR to analyze the transcription level of IL-13 by treatment of IL-19 & IL-21 in Jurkat T cell line. IL-19 & IL-21 induced IL-13 transcript by the activated T cells. Activation of T cells is required for induction of IL-13 because IL-19 & IL-21 did not induce IL-13 production on unstimulated T cells.
Ⅱ. The melanoma differentiation-associated gene 7 (mda-7) was identified by a subtraction hybridization approach from the human HO-1 melanoma cell line. The mda-7 gene belongs to the IL-10 family of cytokines and has recently been classified as IL-24. Introduction of the mda-7/IL-24 gene into a wide variety of cancer cells suppressed growth in vitro and in vivo, with minimal toxicity to normal cells. However, it has not been unkown whether IL-24 has the activity of anti-hepatoma. The purpose of this study was to determine the in vivo tumor suppression function of IL-24 on the hepatoma cells by the approach of intramuscular electroporation. We generated a hepatoma mice model by injecting ML-14acells from mice spleen to allow tumor cells grown at liver. Forty-three days after injection of ML-14a cells. Forty-six percent of mice (N=13) survived from hepatoma compare to seven percent of the negative control. This result demonstrated that IL-24 is a tumor suppressor for hepatoma cells. Also, IL-6 level of mouse serum were higher than negative control. We proposed that anti-tumor mechanism of IL-24 was associated with immunostimulatory activity. However, Treatment of ML-14a cells with IL-24 resulted in no significant antiproliferative activity in vitro. The detailed mechanism of the anti-hepatoma activity of IL-24 should be further studied. IL-24 may be an effective treatment for hepatoma in the future.
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