Metabolites extracted from browntop millet (Urochloa ramosa (L.) T.Q. Nguyen) mitigated the proliferation of breast- and colorectal carcinoma cells in vitro and retarded the EAC tumors in vivo by binding to oncogenic proteins

Abstract

Epidemiological studies have demonstrated an inverse correlation between millet-based diets and incidence of cancers of colon and rectum. These findings highlight the potential of millets as functional foods for effective management of cancers. But the experimental evidences supporting these observations remain limited. Among diverse millet varieties, Browntop millet (BTM) has recently been reported to possess potent anti-oxidant and DNA protection properties. Therefore, in the current study we have hypothesized that metabolite rich fractions of browntop millet, particularly the free metabolites extract (BTM-F), exert anticancer effects by targeting key oncogenic pathways that regulate cell proliferation, cell cycle progression, and apoptosis in breast and colorectal cancers. To test this hypothesis, the study aimed to (a) chemically characterize free and bound metabolites (BTM-F and BTM-B) using UPLC-QTOF-MS; (b) evaluate their anticancer efficacy in vitro and in vivo models; (c) delineate their effects on cell cycle regulation and apoptosis, including modulation of caspase-dependent pathways; and(d) investigate the molecular interactions of identified bioactive metabolite with selected oncogenic protein targets using in silico approaches. Results of the study showed that metabolites of browntop millet contained bioactive phenolics and flavonoids which possessed anticancer potential. Both BTM-F and BTM-B demonstrated significant antioxidant activity and reduced viability of breast- and colorectal cancer cells (IC 50 : 15.36 ± 0.86 to 67.44 ± 7.46 μg/mL). Mechanistically, BTM-F could induce G2/M cell cycle arrest and promoted apoptosis through increased caspase-3 expression and DNA fragmentation. In silico analyses revealed strong binding of key metabolites-Formononetin-7-O-glucuronide, Naringenin-7-O-β-D-glucuronide, and Apigenin-7-glucoside to COX-2 and mtALDH-2. In vivo , BTM-F but not BTM-B significantly suppressed EAC tumor growth. In summary, results of this study for the first time, demonstrated the anti-tumor properties of browntop millet free metabolites in vitro and in vivo . Future studies shall consider BTM-F for testing against patient-derived xenografts and develop functional food-based therapeutic formulation for the better treatment of cancers.