Colon cancer is a common malignant tumor of the digestive tract, and it is considered among the biggest killers. Scientific and reasonable treatments can effectively improve the survival rate of patients if performed in the early stages. Polyphyllin I (PPI), a pennogenyl saponin isolated from Paris polyphylla var. yunnanensis, has exhibited strong anti-cancer activities in previous studies. Here, we report that PPI exhibits a cytotoxic effect on colon cancer cells. PPI suppressed cell viability and induced autophagic cell death in SW480 cells after 12 and 24 h, with the IC50 values 4.9 ± 0.1 μmol/L and 3.5 ± 0.2 μmol/L, respectively. Furthermore, we found PPI induced time-concentration-dependent autophagy and apoptosis in SW480 cells. In addition, down-regulated AKT/mTOR activity was found in PPI-treated SW480 cells. Increased levels of ROS might link to autophagy and apoptosis because reducing the level of ROS by antioxidant N-acetylcysteine (NAC) treatment mitigated PPI-induced autophagy and apoptosis. Although we did not know the molecular mechanism of how PPI induced ROS production, this is the first study to show that PPI induces ROS production and down-regulates the AKT/mTOR pathway, which subsequently promotes the autophagic cell death and apoptosis of colon cancer cells. This present study reports PPI as a potential therapeutic agent for colon cancer and reveals its underlying mechanisms of action.

Tripartite Motif 67 (TRIM67) is an important member of TRIM family proteins, which participates in different cellular processes including immune response, proliferation, differentiation, carcinogenesis, and apoptosis. In recent years, a high fat diet (HFD) has remained one of the main causes of different metabolic diseases and increases in intestinal permeability as well as inducing intestinal inflammation. The current study investigated the protective effects of TRIM67 in the ileum and colon of obese mice. 4-week-old wild-type (WT) C57BL/6N mice and TRIM67 knockout (KO) C57BL/6N mice were selected and randomly divided into four sub-groups, which were fed with control diet (CTR) or HFD for 14 weeks. Samples were collected at the age of 18 weeks for analysis. To construct an in vitro obesity model, over-expressed IPEC-J2 cells (porcine intestinal cells) with Myc-TRIM67 were stimulated with palmitic acid (PA), and its effects on the expression level of TRM67, inflammatory cytokines, and barrier function were evaluated. The KO mice showed pathological lesions in the ileum and colon and this effect was more obvious in KO mice fed with HFD. In addition, KO mice fed with a HFD or CTR diet had increased intestinal inflammation, intestinal permeability, and oxidative stress compared to that WT mice fed with these diets, respectively. Moreover, IPEC-J2 cells were transfected with TRIM67 plasmid to perform the same experiments after stimulation with PA, and the results were found consistent with the in vivo evaluations. Taken together, our study proved for the first time that HFD and TRIM67 KO mice have synergistic damaging effects on the intestine, while TRIM67 plays an important protective role in HFD-induced intestinal damage.

The journal retracts the article titled “Polyphyllin I Promotes Autophagic Cell Death and Apoptosis of Colon Cancer Cells via the ROS-Inhibited AKT/mTOR Pathway”

Salmonella enterica serovar Typhimurium (S. Typhimurium) is an intracellular pathogen that survives and replicates within host cells. Macrophages, key immune cells in infection defense, play a vital role in pathogen clearance through polarization (M1/M2) and NLRP3 inflammasome activation. While TRIM67 regulates macrophage recruitment in the liver, its role in S. Typhimurium infection remains unclear. In this study, a S. Typhimurium infection model was established by orally infecting streptomycin-pretreated TRIM67 WT and KO mice with 1 × 10⁹ CFU of S. Typhimurium. TRIM67 expression in the ileum, colon, mesenteric lymph nodes (MLNs), and peritoneal macrophages (PMs) was assessed via qRT-PCR and Western blotting. Histopathological changes were analyzed using HE and PAS staining. IHC staining, flow cytometry (FCM), qRT-PCR, and Western blotting were used to evaluate TRIM67 knockout effects on macrophage recruitment, polarization, and NLRP3 inflammasome activation. In vitro, PMs were infected with S. Typhimurium (MOI 1:20), and TRIM67’s role in macrophage polarization and NLRP3 activation was validated. S. Typhimurium infection significantly upregulated TRIM67 in the ileum, colon, and MLN. TRIM67 knockout reduced intestinal inflammatory cell infiltration but worsened goblet cell loss and impaired digestion. Bacterial load assays revealed weakened pathogen clearance, leading to weight loss and increased mortality. TRIM67 knockout inhibited intestinal macrophage recruitment, M1 polarization in MLN, and NLRP3 activation. In vitro, TRIM67 knockout increased PMs’ intracellular bacterial load and suppressed NLRP3, caspase-1, and IL-1β expression. TRIM67 knockout impairs the host’s ability to clear S. Typhimurium by inhibiting M1 macrophage polarization and NLRP3 inflammasome activation.