α-fluoro-β-alanine (FBAL), a catabolite of the chemotherapeutic agent 5-fluorouracil (5-FU), has attracted significant attention due to its cardiotoxicity and neurotoxicity. However, its association with 5-FU resistance, a major obstacle in cancer treatment, has rarely been reported. In this study, FBAL was identified as a β-arrestin1-biased ligand of sphingosine 1-phosphate receptor 2 (S1PR2), which upregulates dihydropyrimidine dehydrogenase (DPD) expression and drives 5-FU resistance in colorectal cancer. Mechanistically, following exposure to FBAL, S1PR2, a G protein-coupled receptor (GPCR), is phosphorylated by recruiting G protein-coupled receptor kinase 6 (GRK6). Phosphorylated S1PR2 coupled with β-arrestin1, but not G proteins, to activate the MEK/ERK/AP-1 pathway and promote DPYD transcription. Ser343 was identified as the key phosphorylation site of S1PR2 using IP-MS analysis. This residue within the C-terminal domain mediates receptor interaction with β-arrestin-1 to activate the β-arrestin-1-dependent ERK pathway, as was confirmed in HCT116S1PR2KO-ΔC cells and HCT116S1PR2KO-S343A cells. In vivo, mice bearing orthotopic xenografts of HCT116S1PR2KO-S343A cells exhibited significantly enhanced higher sensitivity to 5-FU treatment compared to those HCT116S1PR2KO-WT cells following FBAL. Taken together, this study showed that exposure to FBAL induces S1PR2 phosphorylation at Ser343 within the C-terminal mediated by GRK6, activating the β-arrestin1-dependent ERK pathway to upregulate DPD expression. This study not only delineates a phosphorylation-dependent signaling pathway in chemoresistance but also establishes S1PR2 as a promising therapeutic target for overcoming 5-FU resistance in cancer.

The therapeutic application of 5-fluorouracil (5-FU) is limited by its rapid metabolism, systemic toxicity, and drug resistance, which motivates the development of efficient polymer-based nanocarriers. In this study, the non-covalent interactions between 5-FU and a chitosan-conjugated poly(lactic-co-glycolic acid) (CS-PLGA) hybrid nanocarrier were investigated using density functional theory (DFT) at the PBE-D3/6-311 + G** level in an aqueous environment modeled via the Polarizable Continuum Model (PCM). Structural analysis indicates that adsorption of 5-FU induces minor elongations in PLGA carbonyl and ester bonds (up to ~ 0.01 Å), along with slight angular distortions, suggesting weak to moderate hydrogen bonding and electrostatic interactions while preserving the structural integrity of the polymer backbone. Adsorption energies ranging from -0.87 to -1.16 eV suggest energetically favorable adsorption of 5-FU on the CS-PLGA surface. Frontier molecular orbital analysis shows a moderate reduction in the HOMO-LUMO gap upon complex formation (ΔEg ≈ 15-17%), accompanied by an increase in dipole moment, indicating enhanced polarity of the drug-carrier system. UV-Vis simulations reveal bathochromic shifts in the absorption maxima (271-295 nm), reflecting electronic perturbations induced by drug adsorption, consistent with excited-state stabilization through hydrogen bonding and local electrostatic interactions. Charge transfer, ESP, and NBO analyses indicate partial electron redistribution from CS-PLGA to 5-FU, particularly in selected configurations, consistent with non-covalent adsorption. Infrared (IR) spectral shifts further support hydrogen-bond-mediated interactions between functional groups of the drug and polymer. Therefore, the results suggest that CS-PLGA provides a stable and responsive environment for 5-FU adsorption, supporting its potential application as a nanocarrier for controlled drug delivery.

5-Fluorouracil (5-FU) is the cornerstone of chemotherapy for patients with advanced colorectal cancer. 5-FU acts primarily by inhibiting thymidylate synthase to prevent DNA and RNA synthesis, causing apoptosis in rapidly dividing cancer cells. Emerging literature indicates that 5-FU also suppresses tumor development by activating tumor-reactive T cells. However, the mechanism underlying 5-FU function in T cell activation in human colorectal cancer remains incompletely understood. In a comparative screening of human colorectal tumor tissues, we found that the levels of CD7[+] cytotoxic T lymphocytes (CTLs) and IL7R[+] CTLs subsets were significantly lower in human colorectal tumor tissues compared to matched adjacent nonneoplastic colon tissues. As expected, 5-FU therapy effectively suppressed colorectal tumor growth and enhanced total CTLs tumor infiltration in tumor-bearing mice. Analysis of tumor-infiltrating CTLs revealed that 5-FU therapy induced CD7[+] and IL7R[+] CTLs differentiation in the mouse colorectal tumor microenvironment. Mechanistically, p53 regulates CD7 and IL7R expression in CTLs by directly binding to the hCD7 and hCD127 promoters, respectively. Functionally, IL7R[+]CD8[+] T cells exhibited improved cytotoxicity with elevated expression of T cell effector genes both in vivo and ex vivo in the mouse colorectal tumor microenvironment. More importantly, 5-FU therapy remarkably promoted CD7[+] and IL7R[+] CTLs tumor infiltration in colorectal cancer patients, as well as facilitated the infiltration of IL7R[+] CTLs subsets in colorectal tumor-bearing mice. Overall, our findings determine that colon cancer suppresses the infiltration of CD7[+] or IL7R[+] CTLs into tumor microenvironment as a mechanism of immune evasion. 5-FU therapy represses colon cancer progression at least in part through activating p53 to foster CD7[+] and IL7R[+] CTLs tumor infiltration, thus proposing a new perspective for the anti-tumor mechanism of 5-FU and a novel, promising therapeutic route by expanding CD7[+] and IL7R[+] CTLs to improve the response to 5-FU chemotherapy.

A 66-year-old man with stage IVB oesophageal carcinoma treated with cisplatin, 5-fluorouracil, and pembrolizumab developed gastric erosions and ulcers with lymphoplasmacytic and neutrophilic infiltrates suggestive of immune checkpoint inhibitor-induced gastritis. High-dose steroids yielded transient relief. Cytomegalovirus (CMV) DNA was later found in gastric biopsies; steroids were withdrawn, and 3 weeks of intravenous ganciclovir led to partial improvement. Subsequent haemorrhagic gastritis raised concern for underlying immunodeficiency; serum immunoglobulin G (IgG), IgA, and IgM were undetectable. Administration of intravenous immunoglobulins (0.8 g/kg) produced rapid clinical resolution. This case report underscores the need for tissue-based CMV testing and cautious steroid use in severe gastritis.

Major objective of hydrothermal method is to achieve the synthesis of Cobalt doped Graphene quantum dots (Co-GQDs) using natural precursor (Boswellia serrata gum resin). The Co-GQDs were surface engineered with folic acid (FA) and hyaluronic acid (HA) to enable dual targeting module (Co-GQDFH), followed by loading of the anticancer drug Exemestane (EXE@Co-GQDs). The nanosized, crystallite structure with high luminescence intensity was maintained after functionalization and drug loading process was assessed from preliminary physicochemical analysis. The EXE@Co-GQDFH forms complex via passive loading approach and achieves and entrapment efficiency of 68.58%. The in-vitro drug release study shows extended release of EXE from the surface functionalized Co-GQDFH for 24 h and releases (~ 88%) maximum encapsulated drug. The dose dependent toxicity was observed for EXE@Co-GQDFH (49.5 µg/ml) on MCF-7 cell breast cancer cell types while IC50 value was comparable to 5-Fluorouracil. The fluorescent Co-GQD shows high bioimaging and cellular uptake efficiency in MCF-7 cells. The surface conjugation with FA and HA on Co-GQDs shows enhanced activity with zone of inhibition was found to be 25 mm while the Co-GQD shows 20 mm suggest conjugation improved the antimicrobial effect. Radical scavenging activity was also demonstrated, with Co-GQDs showing 77.92% and EXE@Co-GQDs was 59.02% DPPH inhibition. These results suggest that surface-engineered Co-GQDs offer a multidentate nanoplatform for targeted delivery, imaging, and therapy in breast cancer applications.

When ribosome biogenesis or function is perturbed, plant cells undergo ribosomal stress, leading to growth defects and developmental alterations. The plant ribosomal stress response has recently gained recognition, but its molecular mechanism remains elusive. Here, we characterized this response in Arabidopsis thaliana using ribosome biogenesis-impairing mutations (rid2 and rid3) and ribosome biogenesis/function-interfering drugs (5-fluorouracil and puromycin) as ribosomal stressors. These stressors repressed cell proliferation and increased ploidy levels indicative of endoreduplication. Under the ribosomal stress conditions, a subset of NAC transcription factor genes and CDK inhibitor genes were upregulated, while they tended to downregulate G2/M-specific genes. Overexpression of ANAC082, which encodes a NAC factor implicated in the ribosomal stress response pathway, phenocopied the ribosomal stress response in the cellular behavior and gene expression. These results together indicated that, predominantly mediated by ANAC082, ribosomal stress arrests the cell cycle at G2 and promotes endoreduplication. Comparison of gene expressions and genetic relations between the ribosomal and DNA damage stress responses, focusing on ANAC082 and the DNA damage stress response-mediating NAC factor SOG1, revealed that these stress response pathways are distinct and largely independent from each other, although they have similar outputs in the control of cell proliferation and endoreduplication.

Patient-derived tumor organoids (PDTOs) are vital for precision oncology, but standard drug screening methods, including adenosine triphosphate (ATP) assays, are destructive and prevent longitudinal monitoring. Optical coherence tomography (OCT) offers non-destructive 3D imaging, capturing morphological features and tissue attenuation characteristics via the optical attenuation coefficient (OAC). Here, we propose a non-destructive evaluation framework for tumor organoids that fuses OAC and multi-dimensional morphological features. Using intrahepatic cholangiocarcinoma (iCCA) PDTOs treated with icaritin, we found that OAC exhibited a significant dose-dependent increase (up to 32.8% at 80 μM compared to control), accompanied by a morphological transition of cystic organoids into solid phenotypes. By integrating these features via K-means++ clustering and principal component analysis, we constructed a relative growth score. This fusion score correlated strongly with the ATP gold standard (Pearson correlation coefficient r = 0.938), outperforming a morphology-only model (r = 0.906). Furthermore, independent experiments with first-line chemotherapeutics (e.g., 5-Fluorouracil, Gemcitabine) and combinatorial regimens indicated the model's potential generalizability (r = 0.887). This method overcomes the limitations of destructive, single-metric evaluations, providing a quantitative and non-destructive platform for high-throughput drug screening and personalized treatment decision-making.

Mismatched-repair-proficient/microsatellite-stable (pMMR/MSS) metastatic colorectal cancer (mCRC) is typically refractory to immune checkpoint inhibitors. Early randomized data suggest that adding PD-1 blockade to anti-angiogenic therapy and oxaliplatin-based chemotherapy may improve outcomes, but real-world evidence remains limited. A 62-year-old woman presented with advanced sigmoid colon adenocarcinoma and liver, lung, and nodal metastases (cT4aN2bM1b). Molecular profiling showed KRAS p.G12D and pMMR/MSS status. First-line treatment with serplulimab, bevacizumab, and XELOX was initiated. After two cycles, carcinoembryonic antigen (CEA) declined from 3458.2 ng/mL to 1812.84 ng/mL. Over eight induction cycles, cross-sectional imaging demonstrated sustained regression of hepatic and pulmonary metastases without new lesions, representing a near-complete response. Following six cycles of maintenance therapy with serplulimab, bevacizumab, and capecitabine, restaging CT and endoscopy showed no visible tumor, consistent with a clinical complete response (cCR), accompanied by resolution of abdominal pain. The patient remains progression-free beyond 12 months at last follow-up. This case illustrates the feasibility and potential of combining PD-1 blockade, anti-VEGF therapy, and oxaliplatin-based chemotherapy for pMMR/MSS mCRC, aligning with efficacy signals from ASTRUM-015 (phase 2 median PFS 17.2 vs 10.7 months; HR 0.60; MSS subgroup 17.2 vs 10.1 months; HR 0.58). Prospective, biomarker-informed trials are warranted to validate patient selection and durability of benefit.