Regulation of 5-fluorodeoxyuridine monophosphate-thymidylate synthase ternary complex levels by autophagy confers resistance to 5-fluorouracil

Pentagalloyl glucose targets the JAK1/JAK3-STAT3 pathway to inhibit cancer stem cells and epithelial-mesenchymal transition in 5-fluorouracil-resistant colorectal cancer

BACKGROUND

Colorectal cancer (CRC) resistance to 5-fluorouracil (5-FU), primarily driven by cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT), remains a major clinical challenge, necessitating novel therapeutic strategies.

PURPOSE

This study aims to evaluate the therapeutic potential of pentagalloyl glucose (PGG), a bioactive compound derived from Bouea macrophylla seeds, in overcoming 5-FU resistance in CRC.

METHOD

Anti-tumor effects of PGG were investigated using two- and three-dimensional (2D and 3D) cell culture models and subcutaneous xenograft and metastatic mouse models. Transcriptome sequencing, western blotting, and pharmacological inhibitors were employed to elucidate the underlying molecular mechanisms.

RESULTS

PGG demonstrated potent anti-CSC activity; suppressed EMT-driven invasion and metastasis; and induced apoptosis in 2D monolayers, 3D spheroid models, and xenograft tumor models. Mechanistically, PGG selectively inhibited the JAK1/JAK3-STAT3 signaling pathway, considerably reducing STAT3 phosphorylation. This disruption downregulated the expression of CSC markers (CD133 and CD44), EMT regulators (N-cadherin and vimentin), and anti-apoptotic proteins (Bcl-2), effectively sensitizing 5-FU-resistant CRC to therapy.

CONCLUSION

PGG inhibit dual-target of CSCs and EMT via JAK1/JAK3-STAT3 signaling pathway in 5-FU-resistant CRC, providing a novel therapeutic approach to overcome chemoresistance.

Anticancer sensitivity and biological aspect of 5-fluorouracil-resistant human colorectal cancer HCT116 cells in three-dimensional culture under high- and low-glucose conditions

5-Fluorouracil (5-FU) is a commonly used anticancer drug for colorectal cancer (CRC). Therefore, it is crucial to elucidate the mechanisms that contribute to 5-FU resistance. We established an acquired 5-FU resistant cell line, HCT116RF10, derived from CRC cells and investigated its energy metabolism as well as the underlying mechanism of 5-FU resistance. We examined the sensitivity to 5-FU and the formation of tumor spheres in parental HCT116 cells and 5-FU-resistant HCT116RF10 cells under 3D culture conditions at high-glucose (HG 25 mM) and low-glucose (LG 5.5 mM) concentrations. These results suggested that the tumor spheres of parental HCT116 cells displayed higher sensitivity to 5-FU under LG conditions than under HG conditions. HCT116RF10 tumor spheres exhibited comparable sensitivity to 5-FU under HG and LG conditions. Furthermore, under HG conditions, there was a marked decrease in extracellular lactate in the HCT116RF10 tumor sphere compared to that in the LG tumor sphere. Similarly, HCT116 tumor spheres showed decreased extracellular lactate levels under LG conditions compared to those grown under HG conditions. Moreover, the evidence reveals that the tumor spheres of HCT116RF10 and HCT116 cells exhibit disparate dependencies on energy metabolism, glycolysis, and mitochondrial respiration under both HG and LG conditions. These results have important clinical implications for overcoming 5-FU resistance and enhancing antitumor treatment strategies.