Exploring tumourigenic potential of the parasite Anisakis: a pilot study.

Anisakiasis is a global disease caused by consumption of raw or lightly cooked fish parasitised with Anisakis spp. third-stage larvae. Cases in the literature show colocalised anisakiasis and colorectal cancer, and the incidental finding of Anisakis larvae at the tumour site was reported. Data from our group suggested an epidemiological link between previous infection and gastrointestinal cancer. Furthermore, it has recently been reported that Anisakis products lead to inflammation and DNA damage. Based on these facts, the aim was to investigate whether Anisakis antigens are able to induce changes in the proliferation of epithelial cells in vitro or in the expression of serum microRNA (miRNA) in Sprague-Dawley rats. Anisakis complete extract (CE) induced increases in cell proliferation and decreases in apoptosis compared with nontreated cells, which resulted in a significant increase in the absolute number of viable cells at 48 h of exposure (P < .05). Furthermore, the miRNAs mmu-miR-1b-5p and mmu-miR-10b-5p (a cancer-related miRNA) were significantly decreased (P < .05) in sera from the rats inoculated with Anisakis CE, compared with control rats inoculated with saline. Additionally, based on their relative quantification values, four other cancer-related miRNAs were considered to be differently expressed, rno-miR-218a-5p and mmu-miR-224-5p (decreased) and rno-miR-125a-3p and rno-miR-200c-3p (increased). Anisakis CE was able to induce changes both in epithelial cells in vitro and in an animal model. The results obtained with Anisakis CE, in terms of increasing cell proliferation, decreasing apoptosis and inducing changes in the expression of serum cancer-related miRNAs in rats, suggest that Anisakis could have tumourigenic potential.