| Summary: | 碩士 === 中山醫學大學 === 醫學分子毒理學研究所 === 96 === Slit2 was identified from a suppressive subtracted cDNA library generated by a set of lung cancer and its adjacent normal counterpart tissues from a female lung adenocarcinoma. Slit2 is a 200kD secreted glycoprotein. It was first identified as a repellent molecule for axon guidance in CNS via signaling through Robo1 receptor. Slit2 also participates in many normal biological functions including cell migration, axon branching, and initiate immune response, etc. Recently, Slit2 has been implicated in pathological development of various cancers. Slit2 promoter was hypermethylated in many cancers indicating that Slit2 possesses tumor suppressor activity. However, Slit2 was also shown to induce angiogenesis in melanoma. Thus, the role of Slit2 in carcinogenesis remains clarified. The expression of Slit2 mRNA was repressed in 95% of female lung adenocarcinoma using microarray analyses. Interestingly, the expression of Slit2 is inversely proportional to invasive ability of CL1 series cell line (established by Dr. Yang P.C.), i.e. the mRNA level of Slit2 is high in low invasive cell lines CL1-0 and CL1-1, but the expression level of Slit2 is low in high invasive cell lines CL1-5 and F4. Since Slit2 mediates cell motility in a variety of cell types, we attempts to hypothesize that Slit2 may affect cell invasion in lung cancer. To study the tumor suppressor role of Slit2 in lung cancer cell lines, RNA interference of Slit2 in CL1-0 cells and overexpression of Slit2 in CL1-5 cells are under investigation. The secreted Slit2 can be proteolytically cleavaged into a 140kD N-terminal and 60kD C-terminal fragments. To understand the role of protein cleavge in Slit2 tumor suppressor activiy, we generated both cleavage site positive and cleavage site negative Slit2 constructs. This thesis focuses on the method of constructing the uncleavable Slit2 by deletion its proteolytic cleavage site.
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