(P13-016-23) Effect of Gold Nanoparticles With Curcin on Pyroptosis Pathway Activation on Antiproliferative Colorectal Cancer Cells

Objectives: The aim was to compare the antiproliferative effect of pure curcin and gold nanoparticles functionalized with curcin on human colon cancer cells HCT-116 and analyze their mechanism of action in in vitro on the pyroptosis pathway regulated by the NLRP3 inflammasome activation.

Methods: Gold nanoparticles (AuNPs) were synthesized by two methods: green synthesis (GS) and citrate reduction (CR), and functionalized with curcin. The antiproliferative effect was evaluated in colon cancer cells (HCT-116) and normal colon cells (CCD-33Co). The MTS assay performed the cytotoxic effect of AuNPs-GS and AuNPs-CR using different concentrations (5, 10, 20, 40, and 80 μM). Apoptosis was evaluated by flow cytometry using the IC₃₀ value of each treatment for 24 h. The markers tested were GAPDH, apoptosis pathway (caspas3/8), markers of the canonical (caspase1, NLRP3, IL-18, IL-1β), and non-canonical (caspase4, GSDMD) pathways. The pyroptosis pathway was measured by western blot and ELISA.

Results: The preparation of the gold nanoparticles was successful, especially the green synthesis. HCT-116 IC₅₀ inhibition values were curcin ( >150 μg/mL), AuNPs-GS (25.62 ± 0.59 μM), and AuNPs-CR (73.33 ± 3.18 μM). CCD-33Co IC₅₀ values were AuNPs GS ( >80 μM) and AuNPs-CR ( >80 μM). IC₃₀ inhibition values tested were curcin (150 μg/mL), AuNPs-CR (31.14 μM), and AuNPs-GS (12.26 μM) on the HCT-116 cells. The percentage of the apoptotic cell population was higher in AuNPs-GS (87.6%), curcin (65.5%), and AuNPs-CR (59.2%) cells than in control (15.6%). Regarding IL-1β expression, curcin (46.81 ±0.05 pg/mL) had the highest level compared to AuNPs-GS (22.61±0.02 pg/mL) and AuNPs-CR (9.31± 0.01 pg/mL). However, AuNPs-GS was the only treatment that induced the expression of IL-18 (127.85 ± 0.0 pg/mL). Markers measured showed an increase in expression of NLRP3 inflammasome, caspase 1, IL-1β, and gasdermin D compared to the control.

Conclusions: The gold nanoparticles synthesized had shown reduced cell viability and increased cytotoxicity in HCT-116. These results suggested that gold nanoparticles promoted the pyroptosis via non-canonical pathway. These treatments promise a new strategy in nanomaterials for biomedical applications.

Funding Sources: CONACyT fellowship, National Polytechnic Institute International Postgraduate Mobility 2022 and the US Department of Agriculture