Blastocystis sp. reduces chemotherapeutic potency of 5- fluorouracil against colorectal cancer

Abstract

Abstract Blastocystis is an enteric protozoan parasite with extensive genetic variation and unclear pathogenicity. It is commonly associated with gastrointestinal symptoms in immunocompromised individuals including colorectal cancer (CRC) patients. In this study, we explored the in vitro and in vivo effects of Blastocystison the activity of a commonly used CRC chemotherapeutic agent, 5-FU. The cellular and molecular effects of solubilized antigen of Blastocystisin the presence of 5-FU were investigated using HCT116, human CRC cell line and CCD 18-Co, normal human colon fibroblast cells. For the in vivo study, 30 male Wistar rats were divided into six groups, as follows; Control Group: oral administration of 0.3ml Jones' medium, Group A: rats injected with azoxymethane (AOM), Group A-30FU: Rats injected with AOM and administered 30mg/kg 5-FU, Group B-A-30FU: rats inoculated with Blastocystis cysts, injected with AOM and administered 30mg/kg 5-FU, Group A-60FU: rats injected with AOM and administered 60mg/kg 5-FU and Group B-A-60FU: rats inoculated with Blastocystis cysts, injected with AOM and administered 60mg/kg 5-FU. The in vitro study revealed that the inhibitory potency of 5-FU at 8µM and 10µM was reduced from 57.7% to 31.6% (p<0.001) and 69.0% to 36.7% (p<0.001) respectively when co-incubated with Blastocystis antigen for 24 hours. However, the inhibitory potency of 5-FU in CCD-18Co cells was not significantly affected in the presence of Blastocystis antigen. The reduced inhibitory potency of 5-FU against cancer cell proliferation due to the presence of Blastocystis is consistent with the upregulation of expression of type 2 cytokines, transforming growth factor (TGF-β) and nuclear factor E2-related factor 2 (Nrf2) gene expression. An increased inflammation and abnormal histopathological findings along with a significant cancer multiplicity and adenoma incidence were evident in the intestine of the B-A-30FU and B-A-60FU groups when compared with the A-30FU and A-60FU groups respectively. Our in vitro and in vivo findings indicate that Blastocystis infection could potentially interfere with chemotherapy regimens such as 5-FU in CRC patients undergoing chemotherapy.