Colon cancer is one of the leading causes of death worldwide. In recent years,
cannabinoids have been extensively studied for their potential anticancer effects and symptom management. Several in vitro studies reported
anandamide's (AEA) ability to block
cancer cell proliferation and migration, but evidence from in vivo studies is still lacking. Thus, in this study, the effects of AEA exposure in zebrafish embryos transplanted with HCT116 cells were evaluated. Totally, 48 hpf xenografts were exposed to 10 nM AEA, 10 nM
AM251, one of the
cannabinoid 1
receptor (CB1) antagonist/inverse agonists, and to AEA + AM251, to verify the specific effect of AEA treatment. AEA efficacy was evaluated by confocal microscopy, which demonstrated that these xenografts presented a smaller
tumor size, reduced
tumor angiogenesis, and lacked
micrometastasis formation. To gain deeper evidence into AEA action, microscopic observations were completed by molecular analyses.
RNA seq performed on zebrafish transcriptome reported the downregulation of genes involved in cell proliferation, angiogenesis, and the immune system. Conversely, HCT116 cell transcripts resulted not affected by AEA treatment. In vitro HCT116 culture, in fact, confirmed that AEA exposure did not affect cell proliferation and viability, thus suggesting that the reduced
tumor size mainly depends on direct effects on the fish rather than on the transplanted
cancer cells. AEA reduced cell proliferation and
tumor angiogenesis, as suggested by socs3 and pcnp mRNAs and Vegfc
protein levels, and exerted anti-inflammatory activity, as indicated by the reduction of il-11a, mhc1uba, and csf3b
mRNA. Of note, are the results obtained in groups exposed to
AM251, which presence nullifies AEA's beneficial effects. In conclusion, this study promotes the efficacy of AEA in personalized
cancer therapy, as suggested by its ability to drive
tumor growth and
metastasis, and strongly supports the use of zebrafish xenograft as an emerging model platform for
cancer studies.