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. We evaluated the 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). After this period, all groups received a balanced diet until week 12. Some animals were euthanised after the last
DMH injection (week 4) for histological, immunohistochemical (Ki-67, γ-H2AX and caspase-3) and molecular analyses (real time-PCR for 91 genes), while other animals were euthanised 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.