Sustained delivery of vemurafenib using polymeric nanocapsules induces apoptosis in anaplastic thyroid carcinoma (8305C cancer cells)

Anaplastic thyroid carcinoma (ATC) is an aggressive malignancy with limited treatment options and a poor prognosis. Although vemurafenib targets the BRAFV600E mutation, its therapeutic efficacy in ATC is limited due to poor solubility and insufficient intracellular retention. In this study, vemurafenib was encapsulated in biocompatible polymeric nanocapsules (VEM-PNCs) to enable sustained intracellular delivery and evaluate its time-dependent anticancer effects. We tested the physical and chemical properties of these nanocapsules and examined their biological effects in human ATC 8305C cells. We measured cell death using MTT assays and assessed programmed cell death (apoptosis) by flow cytometry with Annexin V and Propidium Iodide, Hoechst staining, and microscopic examination. We also measured gene expression changes related to apoptosis and DNA damage using RT-qPCR. The VEM-PNCs produced a delayed onset but prolonged cytotoxic activity compared with free vemurafenib, consistent with controlled intracellular drug release rather than enhanced immediate cytotoxic potency. Empty nanocapsules showed minimal cytotoxicity. Following longer incubation periods, VEM-PNC-treated cells exhibited a higher proportion of apoptotic cells than cells treated with free vemurafenib, suggesting prolonged intracellular drug exposure. These effects were associated with up-regulation of ATM, CHEK2, and TP53, and down-regulation of MDM2 and MDM4, indicating activation of DNA damage response (DDR) and p53-associated signaling pathways. Increased expression of Caspase-3, -8, -9 and BAD suggested that both extrinsic and intrinsic apoptotic pathways were activated. Microscopic examination confirmed apoptotic features, including condensed nuclei and membrane blebbing, in cells treated with VEM-PNCs. These findings suggest that delivering vemurafenib in polymeric nanocapsules produces delayed but sustained cytotoxic and apoptotic effects in ATC cells in vitro, warranting further investigation of this nanocarrier approach for thyroid cancer treatment. Altogether, the biological results reported in this study are derived from in vitro experiments and require further validation in in vivo models.