A double-edged sword effect of silver nanoparticles on angiogenesis in 4T1 breast cancer-bearing mice

Background: Silver nanoparticles (AgNPs) are increasingly known to have anticancer effects, but few studies have examined their adverse effects, so the underlying mechanisms are not yet fully understood. The current study investigated the critical influence of AgNPs on angiogenesis in 4T1 breast cancer-bearing mice.

Methods: The sub-lethal dose of AgNPs (0.25 mg/kg) was carried out. Female BALB/c mice (N = 35) were divided into 7 groups; normal control, cancer control, AgNPs control (one dose of (0.25 mg/kg) AgNPs), single dose AgNPs before cancer, single dose AgNPs after cancer, 5 doses AgNPs after cancer, and doxorubicin. 4T1 breast cancer cell induction was performed subcutaneously on the left flank. Intraperitoneal (IP) administration of AgNPs and doxorubicin was carried out for all studied groups.

Results: Weight gain was normal in all study groups except the doxorubicin-treated group. Administering AgNPs before cancer induction promotes tumorigenesis, raises MMP-2 and MMP-9 activity, and increases CD31 and Ki67 expression. The cancer control group experienced the same outcomes. On the other hand, depending on the administered doses, the injection of AgNPs after tumor induction resulted in a notable decrease in tumor volume. In the doxorubicin-treated group, similar results were observed, while a dose of AgNPs‌ before cancer induction lead to increasing tumor volume compared to the cancer control group. The differences of biochemical markers including LDH, ALP, AST, ALT, BUN, and Cr between different groups were not significant. Significant differences were seen among all studied groups except doxorubicin and single dose AgNPs before cancer groups for serum TAC levels.

Conclusions: It appears that AgNPs are considered a double-edged sword in the fight against cancer. AgNPs not only have anti-cancer effects on tumor size and angiogenesis, but they also might have cancer-stimulating roles. To confirm this conclusion, more detailed investigations are needed.