BACKGROUND

This study sought to examine whether candesartan induces tumor vascular normalization in a narrow therapeutic window to increase perfusion and oxygen content, and thus enhance the effect of radiotherapy (RT).

METHODS

Candesartan was administered to tumor-bearing mice to induce the normalization of tumor vessels, and the time window for normalization was determined. Then, tumor vascular density, perfusion, pericyte coverage, hypoxia of tumor-bearing mice was detected at 3, 6, 9, 12 days, respectively. In the treatment window, RT was administered to enhance the anti-tumor effect, which was evaluated based on relevant anti-tumor indicators. The tumor volume and tumor weight were recorded. Next, tumor growth inhibition rate was calculated according to the tumor weight. The Tunnel and Ki-67 expression of the tumor tissues of every group was measured to evaluate the effects on tumor proliferation and apoptosis.

RESULTS

Based on tumor vascular density, perfusion, pericyte coverage, hypoxia, and other indicators, the tumor vascular normalization window occurred 9 days after the administration of candesartan. The anti-tumor results showed that administering RT during the therapeutic window enhanced anti-tumor efficacy, with a tumor growth inhibition rate of 66.67%. The results of Tunnel and Ki-67 expression showed that window-period RT significantly promoted tumor cell apoptosis and limited proliferation compared to the control group (P<0.05 in Tunnel expression and P<0.01 in Ki-67 expression).

CONCLUSIONS

Candesartan regulates the normalization of tumor vessels and increases the sensitivity of RT in the therapeutic window.