Fu, Lingchen

Abstract Accurate endoscopic marking of suspicious lesions and polyps is essential for the effective surgical management of gastrointestinal (GI) diseases, including colorectal cancer and inflammatory bowel disease. Currently, lesion localization relies on submucosal injection of a carbon-based tattoo ink; however, this ink exhibits extensive tissue diffusion and extravasation, leading to poor spatial fidelity, compromised precision, and risk for fibrotic responses. Given the need for contrast relative to endoscopic white light and biocompatibility, we report here the design and evaluation of melanin-inspired nanoparticle tattoo (MINT) inks, formulated from synthetic melanin nanoparticles and biopolymer-encapsulated synthetic melanin. MINT inks are designed to be durable, high-contrast, easily injectable, and colloidally stable for at least 2 months and to elicit minimal macrophage-mediated inflammatory responses in vitro. In live porcine colon studies, submucosal injection of MINT inks resulted in highly localized tattoos with minimal lateral spread over 9 weeks of follow-up, which is a significant advantage over the extensive diffusion observed with clinical carbon ink. MINT tattoo markings were distinctly visible from both mucosal and serosal surfaces of the intestine and enabled reproducible multipoint and quadrant-based marking, which enhanced spatial orientation. Collectively, these findings demonstrate that MINT inks are biocompatible and capable of providing precise, long-lasting, high-contrast marking of lesions in the colon. By overcoming the limitations of conventional carbon-particle-based tattoos, MINT inks represent a promising next-generation contrast agent for improving endoscopic localization and surgical outcomes in GI diseases.

Abstract The nuclear hormone receptor peroxisome proliferator-activated receptor delta (PPARδ) is a ligand-dependent transcription factor involved in fatty acid metabolism, obesity, wound healing, inflammation, and cancer. Although PPARδ has been shown to promote intestinal adenoma formation and growth, the molecular mechanisms underlying the contribution of PPARδ to colorectal cancer remain unclear. Here, we demonstrate that activation of PPARδ induces expansion of colonic cancer stem cells (CSC) and promotes colorectal cancer liver metastasis by binding to the Nanog promoter and enhancing Nanog expression. Moreover, PPARδ mediated the effect of a high-fat diet in promoting liver metastasis and induction of colonic CSC expansion. Our findings uncover a novel role of dietary fats in colorectal cancer metastasis and reveal novel mechanisms underlying PPARδ-mediated induction of CSCs and those responsible for the contribution of dietary fats to colorectal cancer progression. These findings may provide a rationale for developing PPARδ antagonists to therapeutically target CSCs in colorectal cancer. Significance: These findings show that PPARδ contributes to colorectal cancer metastasis by expanding the CSC population, indicating that antagonists that target PPARδ may be beneficial in treating colorectal cancer.

Significance Our study not only reveals a novel role of peroxisome proliferator-activated receptor δ (PPARδ) in colonic inflammation and colitis-associated tumorigenesis, but also provides some rationale for development of PPARδ antagonists as new therapeutic agents in the treatment of inflammatory bowel disease and colitis-associated colorectal cancer. Moreover, our findings indicate that prostaglandin E 2 generated by chronic inflammation is a crucial mediator connecting chronic inflammation and colorectal carcinogenesis.