Oral Administration of Carotenoid-Rich Dunaliella salina Powder Inhibits Colon Carcinogenesis via Modulation of Wnt/β-catenin Signaling Cascades in a Rat Model

The present study aims to investigate the oral therapeutic and molecular role of carotenoid-rich Dunaliella salina powder (DSP) against 1,2-dimethylhydrazine (DMH)-triggered colon carcinogenesis. In this study, thirty six male Wistar rats were categorized into six distinct groups (G1-G6): G1 group with no intervention, G2 group received only DSP (1000 mg/kg), G3 group received only DMH carcinogen (20 mg/kg), and G4-G6 group received both DMH and DSP at various phases (pre-initiation, post-initiation and entire phases) for 32 weeks. Body weight, tumor incidence, tumor volume, histopathological examination, antioxidants, and detoxification enzymes activities were analyzed in the experimental rats. In addition, the protein expression profile of components involved in the Wnt/beta-catenin signaling pathway was determined by western blot analysis. Matrix metalloproteinases (MMP-7 and MMP-9), proliferation marker (PCNA), and pro-apoptotic (Bcl-2 and Bax) proteins were analyzed using immunohistochemistry. Colorimetric assay was used to determine the levels of anti-inflammatory (iNOS and COX-2) and apoptotic proteins (Caspase-3 and Caspase-9). Results showed that concomitant administration of DSP with DMH significantly reduced tumor progression and prevented colon carcinogenesis in rats. However, treatment with DSP before or after DMH exposure did not significantly prevent colon carcinogenesis. DMH and DSP treatment group showed increased activities of antioxidant enzymes with significant reduction in the oxidative stress. Additionally, the detoxification enzymes and colonic histopathology of those rats were restored to that of control rats. The administration of DSP to rats exposed to DMH exhibited antitumor effects via inhibition of the Wnt/beta-catenin signaling pathway with induced apoptosis through the Bcl-2/Bax/caspases signaling cascades. Moreover, the same group also showed significant anti-inflammatory activity via regulating iNOS and COX-2 biomarkers. Our findings revealed molecular chemopreventive activity of carotenoid-rich DSP through regulating Wnt/beta-catenin and intrinsic apoptotic pathways. Thus, DSP is propound to function as a potent antioxidant, anti-proliferative, and anti-inflammatory therapeutic agent against colon carcinogenesis.