To investigate the suppressing tumor-promoting effects via multi-anti-angiogenesis activity of the copper chelator (Ammonium Tetrathiomolybdate, TM) combined with lenvatinib for hepatocellular carcinoma.
Material and methods
Fifty-five C57 mice were injected subcutaneously with Hepa1-6 hepatoma cell suspensions into the right posterior thigh. Seven days later, all subcutaneous tumors were formed and the mice were randomly distributed into 5 groups: TM Group (G1), Lenvatinib Group (G2), TM+Lenvatinib Group (G3), Control Group (G4), and Copper (II) Gluconate Group (G5). And copper concentrations in serum and tumors were measured at the predetermined times. After fourteen days of treatments, tumor weight and volumes were analyzed, histology was observed, and the expressions of VEGF and microvessel density (MVD) in tumor tissues were measured by immunohistochemistry (IHC).
Average concentration of copper in serum was 405.14 ug/L, 480.44 ug/L, and 679.80 ug/L in normal mice, in mice on 7 days after implantation, and in the control group, respectively. Similarly, intratumoral copper concentrations were greater in G4 mice (1511.90 ug/L) than mice on 7 days after implantation (852.80 ug/L) (p < 0.05). And the serum concentration of copper was 363.65 ug/L, 508.83 ug/L, 370.52 ug/L, 822.12 ug/L in G1, G2, G3, and G5 [G5 vs other Groups, all p < 0.05; (G1, G2, and G3) vs G4, p < 0.05; G1 vs G2, p = 0.013; G2 vs G3, p = 0.018; G1 vs G3, p = 0.903] while intratumoral copper concentrations was 674.31 ug/L, 988.91 ug/L, 550.52 ug/L, and 3004.95 ug/L in G1, G2, G3, and G5 And the average tumor weight was 0.55 g, 0.44 g, 0.08 g, 1.37 g, 3.11 g in the mice of G1, G2, G3, G4, and G5, respectively. [G5 vs other Groups, all p < 0.05; (G1, G2, and G3) vs G4, p < 0.05; G1 vs G3, p < 0.05; G2 vs G3, p < 0.05; G1 vs G2, p > 0.05]. Furthermore, tumors were collected for HE staining and IHC examination. The expression levels of VEGF in G1, G2, and G3 were 43.75, 32.48, and 15, and all of them were significantly lower than those in G4 (64.28) and G5 (89.03) (G4 vs G5, p < 0.05). Similarly, the trend of MVD was just like that of VEGF in the five groups whereas no significant difference occurred in G1 and G2.
The study shows that there is a significant positive correlation between tumor load and copper. Administration of copper can promote tumor progression, and copper chelating could suppress tumor growth. The combination of TM with lenvatinib can reduce tumor angiogenesis and improved the effect of antitumor treatment. These findings offer basic data support and theoretical foundation for the clinical application of the combination therapy.