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Connexin 43 suppresses tumor angiogenesis by down-regulation of vascular endothelial growth factor via hypoxic-induced factor-1α.

Wang WK, Chen MC, Leong HF, Kuo YL, Kuo CY, Lee CH - Int J Mol Sci (2014)

Bottom Line: Previous work showed that connexin 43 (Cx43) reduced the expression of hypoxic-induced factor-1α (HIF-1α) in astrocytes.Furthermore, reduced Cx43 expression in B16F10 and 4T1 cells causes increased expression of VEGF and enhanced the proliferation of endothelial cells.Our findings suggest that Cx43 inhibited tumor growth by reducing angiogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Engineering and Science, Feng Chia University, Taichung 40407, Taiwan. wkwang@fcu.edu.tw.

ABSTRACT
Previous work showed that connexin 43 (Cx43) reduced the expression of hypoxic-induced factor-1α (HIF-1α) in astrocytes. HIF-1α is a master transcription factor for angiogenesis in tumor. Angiogenesis is essential for tumor progression. Here, we investigated the role of Cx43 in vascular endothelial growth factor (VEGF) production and angiogenesis in murine tumor. In the study, mouse B16F10 and 4T1 cells were overexpressed or knockdown with Cx43. The expression profiles as well as activity of the treated cells were examined. Furthermore, reduced Cx43 expression in B16F10 and 4T1 cells causes increased expression of VEGF and enhanced the proliferation of endothelial cells. On the contrary, the expression of VEGF and the proliferation of endothelial were increased in the conditioned medium of Cx43-knockdown tumor cells. We subcutaneously transplanted Cx43-overexpressing B16F10 cells into mice to evaluate the roles of Cx43 in the tumor angiogenesis. Both tumor size and the number of vessels growing in the tumor were markedly decreased compare with control group. Our findings suggest that Cx43 inhibited tumor growth by reducing angiogenesis.

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Cx43 reduced the vessel density. Groups of mice were inoculated with Cx43-overexpressing B16F10 or Cx43-knockdown B16F10 cells (1 × 106) at day 0. Mice were sacrificed at day 16. (a) Tumors were excised at day 16, snap frozen and immunostained with rabbit antibody against factor VIII-related antigen (×400); and (b) Intratumoral microvessel density was determined by averaging the number of vessels in three areas of highest vessel density at ×400 magnification in each section. Scale bar = 100 μm. Data shown were the mean ± SD (n = 4); * p < 0.05.
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ijms-16-00439-f004: Cx43 reduced the vessel density. Groups of mice were inoculated with Cx43-overexpressing B16F10 or Cx43-knockdown B16F10 cells (1 × 106) at day 0. Mice were sacrificed at day 16. (a) Tumors were excised at day 16, snap frozen and immunostained with rabbit antibody against factor VIII-related antigen (×400); and (b) Intratumoral microvessel density was determined by averaging the number of vessels in three areas of highest vessel density at ×400 magnification in each section. Scale bar = 100 μm. Data shown were the mean ± SD (n = 4); * p < 0.05.

Mentions: Microvessel density within tumors from B16F10 tumor-bearing mice were analyzed at 16 days after tumor inoculation by immunohistochemistry. The results of immunohistochemical staining are given in Figure 4a. Tumors from Cx43-overexpressing mice appeared much less vascularized than their control counterparts, whereas no such difference was found between Cx43-overexpressing control and Cx43-knockdown control groups (Figure 4b). Furthermore, microvessel density was apparently increased in the tumors of Cx43-knockdown group compared with the control groups (Figure 4b). Antitumor effects of Cx43 were evaluated in terms of tumor growth in mice bearing Cx43-overexpressing B16F10 melanoma or Cx43-knockdown B16F10 melanoma. Figure 5 shows that tumor growth was significantly retarded in mice with Cx43-overexpressing cells compared with control mice (Figure 5a). By contrast, the tumor growth was slightly increased in Cx43-knockdown B16F10 cell in mice (Figure 5b). Taken together, Cx43 expression vector exerted antitumor effects in melanoma tumor model.


Connexin 43 suppresses tumor angiogenesis by down-regulation of vascular endothelial growth factor via hypoxic-induced factor-1α.

Wang WK, Chen MC, Leong HF, Kuo YL, Kuo CY, Lee CH - Int J Mol Sci (2014)

Cx43 reduced the vessel density. Groups of mice were inoculated with Cx43-overexpressing B16F10 or Cx43-knockdown B16F10 cells (1 × 106) at day 0. Mice were sacrificed at day 16. (a) Tumors were excised at day 16, snap frozen and immunostained with rabbit antibody against factor VIII-related antigen (×400); and (b) Intratumoral microvessel density was determined by averaging the number of vessels in three areas of highest vessel density at ×400 magnification in each section. Scale bar = 100 μm. Data shown were the mean ± SD (n = 4); * p < 0.05.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4307255&req=5

ijms-16-00439-f004: Cx43 reduced the vessel density. Groups of mice were inoculated with Cx43-overexpressing B16F10 or Cx43-knockdown B16F10 cells (1 × 106) at day 0. Mice were sacrificed at day 16. (a) Tumors were excised at day 16, snap frozen and immunostained with rabbit antibody against factor VIII-related antigen (×400); and (b) Intratumoral microvessel density was determined by averaging the number of vessels in three areas of highest vessel density at ×400 magnification in each section. Scale bar = 100 μm. Data shown were the mean ± SD (n = 4); * p < 0.05.
Mentions: Microvessel density within tumors from B16F10 tumor-bearing mice were analyzed at 16 days after tumor inoculation by immunohistochemistry. The results of immunohistochemical staining are given in Figure 4a. Tumors from Cx43-overexpressing mice appeared much less vascularized than their control counterparts, whereas no such difference was found between Cx43-overexpressing control and Cx43-knockdown control groups (Figure 4b). Furthermore, microvessel density was apparently increased in the tumors of Cx43-knockdown group compared with the control groups (Figure 4b). Antitumor effects of Cx43 were evaluated in terms of tumor growth in mice bearing Cx43-overexpressing B16F10 melanoma or Cx43-knockdown B16F10 melanoma. Figure 5 shows that tumor growth was significantly retarded in mice with Cx43-overexpressing cells compared with control mice (Figure 5a). By contrast, the tumor growth was slightly increased in Cx43-knockdown B16F10 cell in mice (Figure 5b). Taken together, Cx43 expression vector exerted antitumor effects in melanoma tumor model.

Bottom Line: Previous work showed that connexin 43 (Cx43) reduced the expression of hypoxic-induced factor-1α (HIF-1α) in astrocytes.Furthermore, reduced Cx43 expression in B16F10 and 4T1 cells causes increased expression of VEGF and enhanced the proliferation of endothelial cells.Our findings suggest that Cx43 inhibited tumor growth by reducing angiogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Engineering and Science, Feng Chia University, Taichung 40407, Taiwan. wkwang@fcu.edu.tw.

ABSTRACT
Previous work showed that connexin 43 (Cx43) reduced the expression of hypoxic-induced factor-1α (HIF-1α) in astrocytes. HIF-1α is a master transcription factor for angiogenesis in tumor. Angiogenesis is essential for tumor progression. Here, we investigated the role of Cx43 in vascular endothelial growth factor (VEGF) production and angiogenesis in murine tumor. In the study, mouse B16F10 and 4T1 cells were overexpressed or knockdown with Cx43. The expression profiles as well as activity of the treated cells were examined. Furthermore, reduced Cx43 expression in B16F10 and 4T1 cells causes increased expression of VEGF and enhanced the proliferation of endothelial cells. On the contrary, the expression of VEGF and the proliferation of endothelial were increased in the conditioned medium of Cx43-knockdown tumor cells. We subcutaneously transplanted Cx43-overexpressing B16F10 cells into mice to evaluate the roles of Cx43 in the tumor angiogenesis. Both tumor size and the number of vessels growing in the tumor were markedly decreased compare with control group. Our findings suggest that Cx43 inhibited tumor growth by reducing angiogenesis.

Show MeSH
Related in: MedlinePlus