Normalizing the disordered tumor vasculature, rather than blocking it, is a novel method for anticancer therapy. Astragali polysaccharide (APS) and curcumin were reported to be active against carcinomas. However, the effect and mechanism of the combination of APS and curcumin on vascular normalization in hepatocellular carcinoma (HCC) was not clear. In the present study, effects of combined APS and curcumin on tumor vascular normalization were evaluated in HepG2 tumor-bearing mice. Photoacoustic tomography (PAT) was performed to observe the morphological structure of tumor vessels in vivo. The microstructure of the tumor vessels was also analyzed through scanning electron microscopy. Additionally, the expression of CD31 and NG2 was analyzed by immunohistochemical staining. Tumor vessels of HepG2 tumor-bearing mice treated with the combination were sparse with uniform growth, morphology rules, and complete vascular walls, which had fewer branches and sprouts. ECs of tumor vessels were arranged regularly and were tightly connected, tending toward normalization. The expression of CD31 was reduced while NG2 was increased significantly by the combination of APS and curcumin. The results indicated that APS and curcumin in combination showed a better effect on inhibiting tumor growth in an orthotopic nude-mouse model of HCC. More important, the combination induced normalization of tumor vascular better than APS or curcumin administration alone, improving the morphological structure of tumor vessels and promoting maturation of tumor vessels. The results of the present study provided a reasonable possibility for combination therapy of APS and curcumin in the treatment of HCC via tumor vascular normalization.
Keywords: Astragali polysaccharide; curcumin; hepatocellular carcinoma; photoacoustic tomography; vascular normalization.