Arenobufagin enhances T-cell anti-tumor immunity in colorectal cancer by modulating HSP90ß accessibility.

BACKGROUND: Colorectal cancer (CRC) is a significant public health issue, ranking as one of the predominant cancer types globally in terms of incidence. Intriguingly, Arenobufagin (Are), a compound extracted from toad venom, has demonstrated the potential to inhibit tumor growth effectively. PURPOSE: This study aimed to explore Are's molecular targets and unravel its antitumor mechanism in CRC. Specifically, we were interested in its impact on immune checkpoint modulation and correlations with HSP90ß-STAT3-PD-L1 axis activity. METHODS: We investigated the in vivo antitumor effects of Are by constructing a colorectalcancer subcutaneous xenograft mouse model. Subsequently, we employed single-cell multi-omics technology to study the potential mechanism by which Are inhibits CRC. Utilizing target-responsive accessibility profiling (TRAP) technology, we identified heatshock protein 90ß (HSP90ß) as the direct target of Are, and confirmed this through a microscale thermophoresis experiment (MST). Further downstream mechanisms were explored through techniques such as co-immunoprecipitation, Western blotting, qPCR, and immunofluorescence. Concurrently, we arrived at the same research conclusion at the organoid level by co-cultivating with immune cells. RESULTS: We observed that Are inhibits PD-Ll expression in CRC tumor xenografts at low concentrations. Moreover, TRAP revealed that HSP90ß's accessibility significantly decreased upon Are binding. We demonstrated a decrease in the activity of the HSP90ß-STAT3-PD-Ll axis following low-concentration Are treatment in vivo. The PDO analysis showed improved enrichment of lymphocytes, particularly T cells, on the PDOs following Are treatment. CONCLUSION: Contrary to previous research focusing on the direct cytotoxicity of Are towards tumor cells, our findings indicate that it can also inhibit tumor growth at lower concentrations through the modulation of immune checkpoints. This study unveils a novel anti-tumor mechanism of Are and stimulates contemplation on the dose-response relationship of natural products, which is beneficial for the clinical translational application of Are.

Identification of the absorbed components and metabolites of Xiao-Ai-Jie-Du decoction and their distribution in rats using ultra high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry.

Xiao-Ai-Jie-Du decoction (XAJDD), a traditional Chinese medicine formula, has long been used for the treatment of hepatocarcinoma, gastric cancer and colorectal cancer. It is composed of six herbal medicines, including Scutellariae Barbatae Herba, Pseudostellariae Radix, Ophiopogonis Radix, Cremastrae Pseudobulbus, Curcumae Rhizoma and Akebiae Fructus. Despite the in-depth study on its pharmacological effects on cancer prevention and treatment, the comprehensive analysis of the chemical components and the absorbed bioactive constituents are not well studied. Thus, an ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) method was established to detect and identify the chemical constituents in XAJDD. The absorbed components and metabolites after oral administration of XAJDD in rats were also studied. In total, 102 components were identified or tentatively characterized in XAJDD, including 30 flavonoids, 19 triterpenoids, 12 organic acids, 9 steroidal saponins, 9 cyclic peptides, 7 phenanthrenes, 5 amino acids, 3 alkaloids and 8 other compounds. After analysing the metabolites in rat plasma and urine after oral administration of XAJDD, a total of 70 compounds were identified, including 15 primary components and 55 metabolites, and metabolic pathways, including hydrogenation, hydroxylation, methylation, sulfonation, and glucuronidation were evaluated. Among these, methylation and glucuronidation were the main metabolic pathways. In conclusion, the developed UHPLC-Q-TOF-MS method with high sensitivity and resolution is suitable for identifying and characterizing the chemical constituents of XAJDD in vitro and characterizing the primary components and their metabolites in vivo; moreover, the results will provide essential data for further studying the relationship between the chemical components and pharmacological activity of XAJDD.

IR820 covalently linked with self-assembled polypeptide for photothermal therapy applications in cancer.

Owing to the unique advantages of high specificity and minimal invasiveness, photothermal therapy (PTT) has been evidenced with great potential in cancer treatment. However, most photothermal agents present a shortage of photobleaching and nonspecific biodistribution in clinical application. In this study, we conjugated a new Indocyanine Green Dye (IR820) with self-assembled polypeptide (ELP) via chemical bonding in an aqueous environment. This preparation method could effectively avoid damaging the polypeptide. ELP-IR820 was fabricated as nanoconjugates with diameters of approximately 50 nm. The use of ELP-IR820 notably enhanced photothermal-mediated cytotoxicity on CT-26 cancer cells. We demonstrate that the ELP-IR820 nanoparticles significantly improved drug accumulation in the tumor and photothermal effect in vivo compared to the free dye and monomer ELP-IR820. ELP-IR820 nanoparticle also exhibited outstanding ability to cause prominent tumor tissue growth inhibition via the photothermal effect. No noticeable toxicity was detected for all treatment groups. These investigations broaden the application of NIR dyes as a multimodal photothermal therapy platform.

Zinc Depletion by TPEN Induces Apoptosis in Human Acute Promyelocytic NB4 Cells.

BACKGROUND/AIMS: The effects of zinc signaling on proliferation or apoptosis of leukemia cells remain elusive. In the present study, we used N, N, N', N'-tetrakis-(2-pyridylmethyl)-ethylene-diamine (TPEN), a membrane-permeable zinc chelator, to evaluate the effect of zinc depletion on survival and apoptosis of NB4 acute promyelocytic leukemia (APL) cells. METHODS: The pro-apoptotic effects of TPEN on NB4 cells were examined by flow cytometry, and observed using an optical microscope. Intracellular labile zinc, nitric oxide (NO) or reactive oxygen species (ROS) changes caused by TPEN were measured by flow cytometry. We then explored possible roles of the crosstalk between intracellular labile zinc signaling and nitric oxide signaling in TPEN-triggered apoptosis. RESULTS: we found that TPEN induced apoptosis in NB4 APL cells in a dosage-dependent manner. We further demonstrated that TPEN triggered apoptosis by attenuating intracellular zinc and nitric oxide signaling in NB4 cells. Both exogenous zinc supplement and the nitric donor sodium nitroprusside (SNP) pre-incubation reversed TPEN-mediated inhibition of intracellular NO and Zn2+ signaling, and rescued NB4 cells from apoptosis. CONCLUSION: These results suggest for the first time that crosstalk between zinc signaling and nitric oxide pathway is essential for the survival of NB4 cells. TPEN induces apoptosis in NB4 cells via negatively regulating intracellular NO and Zn2+ signaling. Our in vitro data suggest that zinc depletion by TPEN may be a potential therapeutic strategy for APL.