Blastocystis sp. subtype 3 triggers higher proliferation of human colorectal cancer cells, HCT116

Abstract

Blastocystis sp. is a commonly found intestinal microorganism and was reported to cause many nonspecific gastrointestinal symptoms. Various subtypes have been previously reported, and the pathogenicity of different subtypes of Blastocystis is unclear and remains as a controversial issue. A recent study has shown that the Blastocystis antigen isolated from an unknown subtype could facilitate the proliferation of colon cancer cells. Current study was conducted to compare the effect of solubilized antigen isolated from five different subtypes of Blastocystis on colon cancer cells, HCT116. A statistically significant proliferation of these cells was observed when exposed to 1.0 μg/ml solubilized antigen isolated from subtype 3 Blastocystis (37.22%, p < 0.05). Real-time polymerase chain reaction demonstrated the upregulation of Th2 cytokines especially transforming growth factor beta in subtype 3-treated cancer cells (p < 0.01, 3.71-fold difference). Of interest, subtype 3 Blastocystis antigen also caused a significantly higher upregulation of cathepsin B (subtypes 1 and 2, p < 0.01; subtypes 4 and 5, p < 0.001; 6.71-fold difference) which lead to the postulation that it may enhance the exacerbation of existing colon cancer cells by weakening the cellular immune response. The dysregulation of IFN-γ and p53 expression also suggest Blastocystis as a proponent of carcinogenesis. Therefore, it is very likely for subtype 3 Blastocystis to have higher pathogenic potential as it caused an increased propagation of cancer cells and substantial amount of inflammatory reaction compared to other subtypes.

Advantage of using colonic washouts for Blastocystis detection in colorectal cancer patients

“…These samples were collected at the initial stage of cancer detection which excluded the possibility of the patients undergoing medical treatments such as chemotherapy which could have killed the parasites. Although pathogenicity of Blastocystis is controversial, Blastocystis screening in CRC patients is crucial considering the recent in vitro studies providing evidences of the parasite’s exacerbating potential in proliferating cancer cells [21-23]. This method probably can be one of the more effective ways to screen for Blastocystis for high risk individuals and those who are suspected of infection but found negative by other less sensitive methods.…”

Elevada prevalencia de Blastocystis spp. en niños de una escuela periurbana

“…Inicialmente fue considerado un comensal; sin embargo, en las últi-mas décadas hay cada vez más evidencias que sustentan que Blastocystis spp. es patógeno y se asocia a una amplia variedad de trastornos gastrointestinales simples (dolor abdominal, diarrea, flatulencia, vómitos) (2,3) y cuadros más complejos, como anemia ferropéni-ca (2) , urticaria (2,4) , síndrome de intestino irritable (2,5,6) , cáncer colorrectal (7)(8)(9) , artritis reactiva (10) e incluso tiroiditis de Hashimoto (11) . El conocimiento de sus múltiples impactos sobre la salud llevó a que se le preste más atención, por lo que probablemente la prevalencia de blastocistosis se haya incrementado en los últimos años.…”

AcuteBlastocystis-Associated Appendicular Peritonitis in a Child, Casablanca, Morocco

“…Indeed, the presence of pathogenic strains among ST3 has been confirmed through experimental infections in rats ( 9 ). Additionally, a substantial inflammatory reaction and an increased propagation of human colorectal cancer cells exposed to Blastocystis ST3 antigens has been demonstrated in vitro ( 10 ). For humans, the pathogenicity of different STs is unclear and remains a debatable issue.…”