Arthrospira (Spirulina) platensis feeding reduces the early stage of chemically-induced rat colon carcinogenesis

Abstract

Colorectal cancer is the third most diagnosed cancer worldwide and linked to dietary/lifestyle factors. Arthrospira (Spirulina) platensis (AP) contains bioactive compounds with beneficial effects in vivo/in vitro. Thus, we evaluated the preventive effects of AP feeding against 1,2- dimethylhydrazine (DMH)-induced colon carcinogenesis. Male Sprague Dawley rats were given subcutaneous injections of DMH (4×40 mg/kg body weight) (G1-G3) or vehicle (G4-G5) twice a week (weeks 3-4). During weeks 1-4, animals were fed a diet containing 1% (G2) or 2% (G3-G4) AP powder (w/w) as a chemopreventive agent. After this period, all groups received a balanced diet until week 12. Some animals were euthanized after the last DMH injection (week 4) for histological, immunohistochemical (Ki-67, γ-H2AX and caspase-3) and molecular analyses (RT-PCR for 91 genes), while other animals were euthanized at week 12 for preneoplastic aberrant crypt foci (ACF) analysis. Both AP treatments (G2-G3) significantly decreased the DMH-induced increase in γ-H2AX (DNA damage) and caspase 3 (DNA damage-induced cell death) in colonic crypts at week 4. In addition, Cyp2e1 (Drug metabolism), Notch1, Notch2, and Jag1 genes (Notch pathway) and Atm, Wee1, Chek2, Mgmt, Ogg1 and Xrcc6 genes (DNA repair) were also down-regulated by 2% AP feeding (G3) at week 4. A significant reduction in ACF development was observed in both AP-treated groups (G2-G3) at week 12. In conclusion, findings indicate that AP feeding reduced acute colonic damage after DMH, resulting in fewer preneoplastic lesions. Our study provided mechanistic insights on dietary AP-preventive effects against early colon carcinogenesis.