• Journal of Life Science
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• v.23 no.10
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• pp.1183-1191
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• 2013

Human apurinic/apyrimidinic endonuclease (APEX-1) is a multifunctional protein that is capable of repairing abasic sites and single-strand breaks in damaged DNA. In addition, it serves as a redox-modifying factor for a number of transcription factors. Identifying the transcriptional targets of APEX-1 is essential for understanding how it affects various cellular outcomes. Expression array analysis was used to identify glial cell-derived neurotropic factor receptor ${\alpha}1$ ($GFR{\alpha}1$), which is an encoding receptor for the glial cell-derived neurotropic factor (GDNF) family, the expression of which is induced by APEX-1. A target of GDNF/$GFR{\alpha}$ signaling, c-Src (Tyr418) was strongly phosphorylated by GNDF in the APEX-1 expressing cells. Moreover, GDNF initiated cell proliferation, measured by counting the number of cells, in the APEX-1 expressing cells. Importantly, the down-regulation of APEX-1 by siRNA caused a marked reduction in the $GFR{\alpha}1$ expression level, and it reduced the ability of GDNF to phosphorylate c-Src (Tyr418) and stimulate cell proliferation. These results demonstrate an association between APEX-1 and GDNF/$GFR{\alpha}$ signaling and suggest a potential molecular mechanism for the involvement of APEX-1 in cell survival and proliferation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.1
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• pp.8-18
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• 2006

Purpose: The purpose of this study was to verify that the expressions of angiogenin, transforming growth factor-beta(TGF-${\beta}$), vascular endothelial growth factor(VEGF), human apurinic/apyrimidinic endonuclease(APEX) and tumor necrosis factor-alpha(TNF-${\alpha}$) were associated with the tumorigenesis of the oral squamous cell carcinoma(OSCC). Materials and Methods: Fifty-one samples of OSCC and fifteen normal oral mucosae were obtained to analyze the expression levels of above five factors. mRNA expressions were quantified by the quantitative competitive PCR(QC-PCR) method. After 2% agarose gel electrophoresis stained with ethidium bromide, the concentration of mRNA was calculated by a digital image analysis system. The expression levels of angiogenin, TGF-${\beta}$, VEGF, APEX and TNF-${\alpha}$ were compared by unpaired Student's t-tests between cancer and normal tissues. We analyzed statistically to find the cut-off values that would be useful as diagnostic markers, and the linear regression analysis between every two factors of these five factors by SAS system. Results: All of these five factors (angiogenin: P<0.0037, TGF-${\beta}$: P<0.0001, VEGF: P<0.0102, APEX: P<0.0023, TNF-${\alpha}$: P<0.0074) were significantly correlated with OSCC. In the analysis to find the cut-off values for the diagnosis, we could not find any value that had a reasonable sensitivity and specificity. In the linear regression analysis, there were correlations between angiogenin and TNF-${\alpha}$, TGF-${\beta}$ and VEGF, TGF-${\beta}$ and APEX, TGF-${\beta}$ and TNF-${\alpha}$, VEGF and APEX, VEGF and TNF-${\alpha}$, APEX and TNF-${\alpha}$. Conclusion: Our results suggest that not only angiogenin, TGF-${\beta}$, VEGF, APEX and TNF-${\alpha}$ are significantly associated with the tumorigenesis, but also the close relationship between these factors might enhance the tumorigenesis of OSCC. We can not find clinical availability for diagnosis.