Objective: To explore the effect of Ang-2 on angiogenesis in gastric cancer.
Methods: The expression of Ang-2 mRNA was analyzed by RT-PCR and the expression of VEGF and CD34 was detected by immunohistochemistry in 36 cases of gastric cancer tissues and their paired adjacent gastric mucosa.
Results: The expression of Ang-2 mRNA was found both in gastric cancer and their paired adjacent gastric mucosa; the correlationship between the general expression levels of Ang-2 mRNA and microvessel density (MVD) in gastric cancer tissues was not found. However, in 27 cases whose Ang-2 mRNA expression levels in cancer tissues were lower than those in adjacent gastric mucosa. A significant positive correlation between the expression level of Ang-2 mRNA and MVD in the tumor tissues was found (r = 0.411, P < 0.05). In these 27 cases, the MVD in the gastric cancer tissues with positive VEGF expression (45.45 +/- 10.30) was higher than that with negative VEGF expression (30.15 +/- 8.69, P < 0.05), whereas in the other 9 cases whose expression levels of Ang-2 mRNA in cancer tissues were higher than those in adjacent gastric mucosa, a significant negative correlation between expression level of Ang-2 mRNA and MVD in the tumor tissues (r = -0.758, P < 0.05), but without correlation between the MVD and VEGF.
Conclusion: Under the conditions that the expression of Ang-2 mRNA in cancer tissues was lower than that in adjacent gastric mucosa, VEGF could promote the sprouting of new vessels along with Ang-2 upregulation. But under the conditions that the expression of Ang-2 mRNA in cancer tissues was higher than that in adjacent gastric mucosa, Ang-2 inhibited angiogenesis. Angiopoietin-2 may play a dual effect on angiogenesis in gastric cancer.