Understanding how castration-resistant prostate cancer (CRPC) cells survive the androgen-deprivation condition is crucial for treatment of this advanced prostate cancer (PCa). Here, we reported for the first time the up-regulation of protein S (PROS), an anticoagulant plasma glycoprotein with multiple biological functions, in androgen-insensitive PCa cells and in experimentally induced castration-resistant PCa cells. Overexpression of exogenous PROS in LNCaP cells reduced androgen deprivation-induced apoptosis and enhanced anchorage-dependent clonogenic ability under androgen deprivation condition. Reciprocally, PROS1 knockdown inhibited cell invasiveness and migration, caused the growth inhibition of castration-resistant tumor xenograft under androgen-depleted conditions, and potentiated Taxol (a widely prescribed anti-neoplastic agent)-mediated cell death in PC3 cells. Furthermore, PROS overexpression significantly stimulated AKT activation but failed to evoke oxidative stress in LNCaP cells under normal condition, suggesting that the malignance-promoting effects of the above-mentioned pathway may occur in the order of oxidative stress/PROS/AKT. The potential mechanism may be due to control of oxidative stress-elicited activation of PI3K-AKT-mTOR pathway. Taken together, our gain-of-function, loss-of-function analyses suggest that PROS may facilitate cell proliferation and promote castration resistance in human castration-resistant PCa-like cells via its apoptosis-regulating property. Future study emphasizing on delineating how PROS regulate cellular processes controlling transformation during the development of castration resistance should open new doors for the development of novel therapeutic targets for CRPC.

The targeted delivery of nanomedicines into solid tumors remains challenging in cancer treatment. Stem cells with tumortropic migration ability are promising as biocarriers to transport nanomedicines. The transportation of nanomedicines into cancer cells is the key step for tumor targeted delivery via stem cells. In this study, we designed a magnetic nanocube (scMNP) loaded in mesenchymal stem cells for magnetic hyperthermia of prostate cancer, and the delivery and transportation pathways into the cancer cells were fully investigated. The MSCs acted as the carrier of the loaded scMNPs along with the upregulation of CXCR4 for the migration to cancer cells. The therapeutic effect was mainly due to scMNPs via magnetic hyperthermia. Stem cell-derived microvesicles containing scMNPs played an essential role in the crosstalk between stem cells and cancer cells for targeted delivery. Both in vitro and in vivo studies demonstrated that the system showed satisfactory therapeutic efficiency under magnetic hyperthermia therapy. Our investigation presents a comprehensive study of magnetic nanoparticles in combination with MSCs and their extracellular microvesicles and is promising as an effective strategy for magnetic hyperthermia therapy of prostate cancer.