Resveratrol and its Nanoparticle suppress Doxorubicin/Docetaxel-resistant anaplastic Thyroid Cancer Cells in vitro and in vivo

Background: Docetaxel and doxorubicin combination has been widely used in anaplastic thyroid cancer/ATC treatment but often results in serious adverse effects and drug resistance. Resveratrol effectively inhibits ATC cell proliferation in vitro without affecting the corresponding normal cells, while its in vivo anti-ATC effects especially on the ones with docetaxel/doxorubicin-resistance have not been reported due to its low bioavailability. Nanoparticles with sustained-release and cancer-targeting features may overcome this therapeutic bottleneck. Methods: The resveratrol nanoparticles with sustained-release and IL-13Rα2-targeting capacities (Pep-1-PEG(3.5k)-PCL(4k)@Res) were prepared to improve the in vivo resveratrol bioavailability. Human THJ-16T ATC cell line was employed to establish nude mice subcutaneous transplantation model. The tumor-bearing mice were divided into four groups as Group-1, without treatment, Group-2, treated by 30 mg/kg free resveratrol, Group-3, treated by 30 mg/kg Pep-1-PEG(3.5k)-PCL(4k)@Res and Group-4, treated by 5 mg/kg docetaxel/5 mg/kg doxorubicin combination. TUNEL staining was used to detect the apoptotic cells in the tumor tissues. Docetaxel/doxorubicin resistant xenografts named as THJ-16T/R were isolated and subjected to 2D and 3D culture. The docetaxel/doxorubicin and resveratrol sensitivities of the original THJ-16T and THJ-16T/R cells were analyzed by multiple methods. Results: Docetaxel/doxorubicin and Pep-1-PEG(3.5k)-PCL(4k)@Res but not free resveratrol significantly delayed tumor growth (P < 0.01) and caused extensive apoptosis. The mice in docetaxel/doxorubicin-treated group suffered from weight loss (> 10%) and 2/3 of them died within 3 times of treatment and the chemotherapy was stop to avoid further animal loss. One week after drug withdrawal, the subcutaneous tumors regrew and the tumor volume increased 55.28% within 14 days. The cells isolated from the regrowing tumors (THJ-16T/R) were successfully cultured under 2D and 3D condition and underwent drug treatments. Compared with THJ-16T, the death rate of docetaxel/doxorubicin-treated THJ-16T/R population was lower (39.3% vs 18.0%), which remained almost unchanged in resveratrol-treated group (45.3% vs 49.3%). Conclusion: Resveratrol sustained-release targeting nanoparticles effectively inhibit in vivo ATC growth. Docetaxel/doxorubicin suppresses ATC xenografts but causes obvious side effects and secondary drug resistance that can be overcome by resveratrol.