| Summary: | 碩士 === 國立中興大學 === 生物科技學研究所 === 98 === Phosphoglucose isomerase (PGI) is a multifunctional protein ubiquitously expressed in cell. Inside the cells, it catalyzes the interconversion of glucose-6-phosphate (G6P) and fructose-6-phosphate (F6P), the second step of the glycolytic pathway. Outside the cells, PGI moonlights as an autocrine motility factor (AMF) involved in cancer metastasis development. PGI can also function as a neuroleukin that facilitates survival and growth of embryonic spinal and sensory neurons; a maturation factor mediating the differentiation of myeloid leukemic HL-60 cells to terminal monocytic cells. AMF/PGI is secreted by tumor cells to detectable levels in both serum and urine and thus has been used as a prognostic marker of cancer progression. Previous study discovered that human PGI (hPGI) could bind to GTP; however, the physiological significance of interaction is unknown. Thus, to realize the effects of the interaction between hPGI and GTP on cell proliferation, hPGI and/or GTP was added into the culture media of A549 and HEK293 cell lines. Cell viability was quantified after 48 hours incubation by using MTT and WST-1 assays. The data showed that GTP decreased cell proliferation when its concentration was more than 50 uM, whereas hPGI (0.16 uM、0.79 uM) enhanced proliferation about 10%-20%. However, treatment of hPGI with low GTP concentrations (i.e. 25 uM and 50 uM) caused a decline in the number of cells. By Hoechst 33342 staining used to observe nuclear morphological changes, A549 cells exhibited condensed chromatin gathering with the co-treatment of hPGI and GTP suggesting the binding of hPGI to GTP may induce apoptosis of A549 cells. To study the effects of hPGI and GTP on cell motility, the migration rates of HepG2 and CT-26 cell lines were assayed by transwell. hPGI and GTP inhibited the cell motility-stimulating activity of AMF/PGI. Compared to the cells with hPGI, co-treatment of hPGI and GTP reduced the migration rate by 90% and 50% on HepG2 cells and CT-26 cells respectively. These results implicating there is an unknown mechanism of inhibition of the cell locomotion by hPGI-GTP.
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