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Human apurinic/apyrimidinic endonuclease siRNA inhibits the angiogenesis induced by X-ray irradiation in lung cancer cells.

Gu X, Cun Y, Li M, Qing Y, Jin F, Zhong Z, Dai N, Qian C, Sui J, Wang D - Int J Med Sci (2013)

Bottom Line: APE1 and VEGF high expression were significantly associated with reduced disease free survival (DFS) time.Silencing of APE1 by Ad5/F35-APE1 siRNA significantly decreased DNA binding activity of HIF-1α and suppressed the expression of VEGF in A549 cells, moreover, significantly inhibited the endothelial cells immigration and capillary-like structure formation induced by irradiated A549 cells.Our results indicate that APE1 may play a crucial role in angiogenesis induced by irradiation.

View Article: PubMed Central - PubMed

Affiliation: Cancer Center, Daping Hospital and Research Institute of Surgery, Third Military Medical University, Chongqing 400042, China.

ABSTRACT

Objective: Radiotherapy is an important and effective treatment method for non-small cell lung cancer (NSCLC). Nonetheless, radiotherapy can alter the expression of proangiogenic molecules and induce angiogenesis. Human apurinic/apyrimidinic endonuclease (APE1) is a multifunctional protein, which has DNA repair and redox function. Our previous studies indicated APE1 is also a crucial angiogenic regulator. Thus, we investigated the effect of APE1 on radiation-induced angiogenesis in lung cancer and its underlying mechanism.

Methods: Tumor specimens of 136 patients with NSCLC were obtained from 2003 to 2008. The APE1 and vascular endothelial growth factor (VEGF) expression, as well as microvessel density (MVD) were observed with immunohistochemistry in tumor samples. Human lung adenocarcinoma A549 cells were treated with Ad5/F35-APE1 siRNA and/or irradiation, and then the cells were used for APE1 analysis by Western blot and VEGF analysis by RT-PCR and ELISA. To elucidate the underline mechanism of APE1 on VEGF expression, HIF-1α protein level was determined by Western blot, and the DNA binding activity of HIF-1α was detected by EMSA. Transwell migration assay and capillary-like structure assay were used to observe the migration and capillary-like structure formation ability of human umbilical veins endothelial cells (HUVECs) that were co-cultured with Ad5/F35-APE1 siRNA and (or) irradiation treated A549 cells culture medium.

Results: The high expression rates of APE1 and VEGF in NSCLC were 77.94% and 66.18%, respectively. The expressions of APE1 was significantly correlated with VEGF and MVD (r=0.369, r=0.387). APE1 and VEGF high expression were significantly associated with reduced disease free survival (DFS) time. The high expressions of APE1 and VEGF on A549 cells were concurrently induced by X-ray irradiation in a dose-dependent manner. Silencing of APE1 by Ad5/F35-APE1 siRNA significantly decreased DNA binding activity of HIF-1α and suppressed the expression of VEGF in A549 cells, moreover, significantly inhibited the endothelial cells immigration and capillary-like structure formation induced by irradiated A549 cells.

Conclusion: Our results indicate that APE1 may play a crucial role in angiogenesis induced by irradiation. Administration of Ad5/F35-APE1 siRNA during radiotherapy could be a potent adjuvant therapeutic approach to enhance the radiotherapy response, effectively eliminate metastasis and improve the efficacy of radiotherapy for NSCLC.

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Related in: MedlinePlus

Kaplan-Meier analysis of the effect of APE1 and VEGF levels on survival.
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Figure 2: Kaplan-Meier analysis of the effect of APE1 and VEGF levels on survival.

Mentions: DFS time was accounted from the day of surgery until recurrence or metastasis. The data of the patients without recurrence or metastasis until June 2011 were censored. Kaplan-Meier survival curves and the log-rank test were used to analyze univariate distributions for DFS. Results showed that the 1-, 3- and 5-year DFS rates were 65.4%, 44.6% and 42.3%, respectively. Figure 2 shows that APE1 higher expression levels had a significantly shorter DFS time compared with APE1 lower expression group, and VEGF high expression is associated with reduced survival. Moreover, the multivariate analysis by COX regression model showed that tumor size, lymphatic nodal status and VEGF expression level were the important independent prognosis factors, which indicated that APE1 expression level may not be an independent prognostic factor in NSCLC.


Human apurinic/apyrimidinic endonuclease siRNA inhibits the angiogenesis induced by X-ray irradiation in lung cancer cells.

Gu X, Cun Y, Li M, Qing Y, Jin F, Zhong Z, Dai N, Qian C, Sui J, Wang D - Int J Med Sci (2013)

Kaplan-Meier analysis of the effect of APE1 and VEGF levels on survival.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3675501&req=5

Figure 2: Kaplan-Meier analysis of the effect of APE1 and VEGF levels on survival.
Mentions: DFS time was accounted from the day of surgery until recurrence or metastasis. The data of the patients without recurrence or metastasis until June 2011 were censored. Kaplan-Meier survival curves and the log-rank test were used to analyze univariate distributions for DFS. Results showed that the 1-, 3- and 5-year DFS rates were 65.4%, 44.6% and 42.3%, respectively. Figure 2 shows that APE1 higher expression levels had a significantly shorter DFS time compared with APE1 lower expression group, and VEGF high expression is associated with reduced survival. Moreover, the multivariate analysis by COX regression model showed that tumor size, lymphatic nodal status and VEGF expression level were the important independent prognosis factors, which indicated that APE1 expression level may not be an independent prognostic factor in NSCLC.

Bottom Line: APE1 and VEGF high expression were significantly associated with reduced disease free survival (DFS) time.Silencing of APE1 by Ad5/F35-APE1 siRNA significantly decreased DNA binding activity of HIF-1α and suppressed the expression of VEGF in A549 cells, moreover, significantly inhibited the endothelial cells immigration and capillary-like structure formation induced by irradiated A549 cells.Our results indicate that APE1 may play a crucial role in angiogenesis induced by irradiation.

View Article: PubMed Central - PubMed

Affiliation: Cancer Center, Daping Hospital and Research Institute of Surgery, Third Military Medical University, Chongqing 400042, China.

ABSTRACT

Objective: Radiotherapy is an important and effective treatment method for non-small cell lung cancer (NSCLC). Nonetheless, radiotherapy can alter the expression of proangiogenic molecules and induce angiogenesis. Human apurinic/apyrimidinic endonuclease (APE1) is a multifunctional protein, which has DNA repair and redox function. Our previous studies indicated APE1 is also a crucial angiogenic regulator. Thus, we investigated the effect of APE1 on radiation-induced angiogenesis in lung cancer and its underlying mechanism.

Methods: Tumor specimens of 136 patients with NSCLC were obtained from 2003 to 2008. The APE1 and vascular endothelial growth factor (VEGF) expression, as well as microvessel density (MVD) were observed with immunohistochemistry in tumor samples. Human lung adenocarcinoma A549 cells were treated with Ad5/F35-APE1 siRNA and/or irradiation, and then the cells were used for APE1 analysis by Western blot and VEGF analysis by RT-PCR and ELISA. To elucidate the underline mechanism of APE1 on VEGF expression, HIF-1α protein level was determined by Western blot, and the DNA binding activity of HIF-1α was detected by EMSA. Transwell migration assay and capillary-like structure assay were used to observe the migration and capillary-like structure formation ability of human umbilical veins endothelial cells (HUVECs) that were co-cultured with Ad5/F35-APE1 siRNA and (or) irradiation treated A549 cells culture medium.

Results: The high expression rates of APE1 and VEGF in NSCLC were 77.94% and 66.18%, respectively. The expressions of APE1 was significantly correlated with VEGF and MVD (r=0.369, r=0.387). APE1 and VEGF high expression were significantly associated with reduced disease free survival (DFS) time. The high expressions of APE1 and VEGF on A549 cells were concurrently induced by X-ray irradiation in a dose-dependent manner. Silencing of APE1 by Ad5/F35-APE1 siRNA significantly decreased DNA binding activity of HIF-1α and suppressed the expression of VEGF in A549 cells, moreover, significantly inhibited the endothelial cells immigration and capillary-like structure formation induced by irradiated A549 cells.

Conclusion: Our results indicate that APE1 may play a crucial role in angiogenesis induced by irradiation. Administration of Ad5/F35-APE1 siRNA during radiotherapy could be a potent adjuvant therapeutic approach to enhance the radiotherapy response, effectively eliminate metastasis and improve the efficacy of radiotherapy for NSCLC.

Show MeSH
Related in: MedlinePlus