Oleanolic acid improves 5-fluorouracil-induced intestinal damage and inflammation by alleviating intestinal senescence

5-Fluorouracil (5-FU) is used as a standard first-line drug for colorectal cancer malignancy (CRC), but it brings a series of side effects such as severe diarrhea and intestinal damage. Our previous study found that a large number of senescent cells increased while 5-Fu induced intestinal damage, and anti-senescence drugs can alleviate its side effects of inflammatory damage. Oleanolic acid (OA) is a common pentacyclic triterpenoid mainly derived from food fungi and medicinal plants, and studies have shown that it mainly possesses hepatoprotective, enzyme-lowering, anti-inflammatory, and anti-tumor effects. But its role in senescence is still unclear. In the present study, we demonstrated for the first time that OA ameliorated 5-Fu-induced human umbilical vein endothelial cells (HUVECs) and human normal intestinal epithelial cells (NCM460) in a 5-Fu-induced cellular senescence model by decreasing the activity of SA-β-gal-positive cells, and the expression of senescence-associated proteins (p16), senescence-associated genes (p53 and p21), and senescence-associated secretory phenotypes (SASPs: IL-1β, IL-6, IL-8, IFN-γ and TNF-α). Meanwhile, in this study, in a BALB/c mouse model, we demonstrated that 5-FU induced intestinal inflammatory response and injury, which was also found to be closely related to the increase of senescent cells, and that OA treatment was effective in ameliorating these adverse phenomena. Furthermore, our in vivo and in vitro studies showed that OA could alleviate senescence by inhibiting mTOR. In colon cancer cell models, OA also enhanced the ability of 5-FU to kill HCT116 cells and SW480 cells. Overall, this study demonstrates for the first time the potential role of OA in counteracting the side effects of 5-FU chemotherapy, providing a new option for the treatment of colorectal cancer to progressively achieve the goal of high efficacy and low toxicity of chemotherapy.