PIM kinase inhibitor AZD1208 for treatment of MYC-driven prostate cancer.

BACKGROUND: PIM1 kinase is coexpressed with c-MYC in human prostate cancers (PCs) and dramatically enhances c-MYC-induced tumorigenicity. Here we examine the effects of a novel oral PIM inhibitor, AZD1208, on prostate tumorigenesis and recurrence. METHODS: A mouse c-MYC/Pim1-transduced tissue recombination PC model, Myc-CaP allografts, and human PC xenografts were treated with AZD1208 (n = 5-11 per group). Androgen-sensitive and castrate-resistant prostate cancer (CRPC) models were studied as well as the effects of hypoxia and radiation. RNA sequencing was used to analyze drug-induced gene expression changes. Results were analyzed with χ(2) test. Student's t test and nonparametric Mann-Whitney rank sum U Test. All statistical tests were two-sided. RESULTS: AZD1208 inhibited tumorigenesis in tissue recombinants, Myc-CaP, and human PC xenograft models. PIM inhibition decreased c-MYC/Pim1 graft growth by 54.3 ± 39% (P < .001), decreased cellular proliferation by 46 ± 14% (P = .016), and increased apoptosis by 326 ± 170% (P = .039). AZD1208 suppressed multiple protumorigenic pathways, including the MYC gene program. However, it also downregulated the p53 pathway. Hypoxia and radiation induced PIM1 in prostate cancer cells, and AZD1208 functioned as a radiation sensitizer. Recurrent tumors postcastration responded transiently to either AZD1208 or radiation treatment, and combination treatment resulted in more sustained inhibition of tumor growth. Cell lines established from recurrent, AZD1208-resistant tumors again revealed downregulation of the p53 pathway. Irradiated AZD1208-treated tumors robustly upregulated p53, providing a possible mechanistic explanation for the effectiveness of combination therapy. Finally, an AZD1208-resistant gene signature was found to be associated with biochemical recurrence in PC patients. CONCLUSIONS: PIM inhibition is a potential treatment for MYC-driven prostate cancers including CRPC, and its effectiveness may be enhanced by activators of the p53 pathway, such as radiation.

Stretching fibroblasts remodels fibronectin and alters cancer cell migration.

Most investigations of cancer-stroma interactions have focused on biochemical signaling effects, with much less attention being paid to biophysical factors. In this study, we investigated the role of mechanical stimuli on human prostatic fibroblasts using a microfluidic platform that was adapted for our experiments and further developed for both repeatable performance among multiple assays and for compatibility with high-resolution confocal microscopy. Results show that mechanical stretching of normal tissue-associated fibroblasts (NAFs) alters the structure of secreted fibronectin. Specifically, unstretched NAFs deposit and assemble fibronectin in a random, mesh-like arrangement, while stretched NAFs produce matrix with a more organized, linearly aligned structure. Moreover, the stretched NAFs exhibited an enhanced capability for directing co-cultured cancer cell migration in a persistent manner. Furthermore, we show that stretching NAFs triggers complex biochemical signaling events through the observation of increased expression of platelet derived growth factor receptor α (PDGFRα). A comparison of these behaviors with those of cancer-associated fibroblasts (CAFs) indicates that the observed phenotypes of stretched NAFs are similar to those associated with CAFs, suggesting that mechanical stress is a critical factor in NAF activation and CAF genesis.