Castor oil

All reagents were used as received. PVC was supplied from rhawn.cn (K value 59–55). Potassium carbonate (K₂CO₃) (AR) and tetrahydrofuran (THF) (AR) were obtained from Sinopharm Chemical Reagent Co., Ltd (China). Diethanolamine (DEA) (AR), hexamethylene diisocyanate (HDI) (>99%), hexamethylene diisocyanate trimer (THDI) (>99%), isophorone diisocyanate (IPDI) (>99%), castor oil (AR), dibutyltin dilaurate (AR) and petroleum ether were offered by Shanghai Macklin Biochemical Co., Ltd (China).

Human lung cancer cell lines A549 and H1299, human liver cancer cell lines HepG2 and Huh7, human breast cancer cell lines T-47D and MB231, human colon cancer cell line SW480, rat cardiac myoblast H9c2, were obtained from the American Type Culture Collection (Manassas, VA, USA) and Institute of Biochemistry and Cell Biology (CAS, Shanghai), passaged five to six times before use. Cells were cultured in Dulbecco's modified Eagle's medium (Hyclone, Logan, UT, USA), containing 10% fetal bovine serum (Biochrom AG, Berlin, Germany) and 100 units/mL penicillin/streptomycin solution and maintained in a humidified atmosphere of 5% CO₂ at 37 °C (standard culture conditions). MLN4924, CAR, and CAR derivatives were dissolved in dimethyl sulfoxide (DMSO) and kept at −20 °C for in vitro studies. MLN4924, CAR, or 43 were dissolved respectively in 5% 2-hydroxypropyl-β-cyclodextrin and 5% castor oil (Macklin Reagent, Shanghai, China), while doxorubicin (DOX) was dissolved in saline in vivo studies. The solution of tested agents was freshly made every day when was used.