015 | A flavonoid-rich extract of bergamot juice modulates redox homeostasis and apoptosis in colorectal cancer experimental models

Martina Farina¹, Alessandro Maugeri², Michele Navarra¹ | ¹Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Italy; ²Department of Veterinary Sciences, University of Messina, Italy.

Colorectal cancer (CRC) is the second leading cause of cancer-related mortality worldwide, highlighting the urgent need for novel preventive and therapeutic strategies with improved safety profiles. Increasing evidence indicates that natural products rich in polyphenols may act as multitarget agents capable of modulating key oncogenic pathways. In this context, the present study was aimed at evaluating the antitumor potential of a flavonoid-rich extract of bergamot juice (BJe) in established in vitro and in vivo models of CRC, with a specific focus on the molecular mechanisms involved. BJe significantly inhibited the proliferation of multiple CRC cell lines, with HCT-116 cells showing the highest sensitivity. In this cell line, BJe induced both early and late apoptosis and blocked the cell cycle in the G1 phase. These effects were associated with the upregulation of the gene expression of pro-apoptotic markers TP53, BAX, CASP3 and CASP9, along with a downregulation of the anti-apoptotic BCL2. In parallel, cell cycle-blocking capacity of BJe was linked to an upregulation of CDKN1A and a downregulation of CCND1, two pivotal players in the G1 phase regulation. Moreover, we observed that BJe disrupted redox balance by increasing intracellular reactive oxygen species and impairing mitochondrial membrane potential, thereby triggering oxidative stress–mediated cell death. Diving deeper into the fine molecular events, we found that BJe was able to induce DNA oxidative damage, as demonstrated by the increase of levels of the oxidized nucleobase 8-oxo-2'-deoxyguanosine, as well as phosphorylation of histone H2A.X, known marker of double-strand breaks. The translational relevance of these findings was further supported in vivo using an azoxymethane-induced murine model of sporadic CRC. Oral administration of BJe significantly reduced the number of aberrant crypt foci and decreased the percentage of mice bearing both polyps and tumors, together with their number. Overall, these results indicate that BJe induced oxidative stress, prompted apoptosis and cell cycle blockage, as well as suppressed early tumorigenic events, confirming its role in counteracting CRC, offering new insights into its mechanisms of action.