The new generation androgen receptor (AR) pathway inhibitor enzalutamide can prolong the survival of patients with metastatic prostate cancer. However, resistance to enzalutamide inevitably develops in these patients, and the underlying mechanisms of this resistance are not fully defined. Here we demonstrate that the kinesin family member 15 (KIF15) contributes to enzalutamide resistance by enhancing the AR signaling in prostate cancer cells. KIF15 directly bound the N-terminus of AR/AR-V7 and prevented AR/AR-V7 proteins from degradation by increasing the protein association of ubiquitin-specific protease 14 (USP14) with AR/AR-V7. In turn, the transcriptionally active AR stimulated KIF15 expression. KIF15 inhibitors alone or in combination with enzalutamide significantly suppressed enzalutamide-resistant prostate cancer cell growth and xenograft progression. These findings highlight a key role of KIF15 in enabling prostate cancer cells to develop therapy resistance to enzalutamide and rationalize KIF15 as a potential therapeutic target. Significance: These findings demonstrate how reciprocal activation between KIF15 and AR contributes to enzalutamide resistance in prostate cancer and highlights cotargeting KIF15 and AR as a therapeutic strategy for these tumors.

Numerous studies have demonstrated that rheumatoid arthritis (RA) is often associated with bone loss; however, few experiments have focused on cancellous and cortical bone changes in rats during the process of arthritis. We have investigated bone changes in rats with collagen-induced arthritis (CIA) and have explored the characteristics of how RA induces osteoporosis by means of bone histomorphometry, bone biomechanics studies, bone mineral density studies, micro computer tomography, enzyme-linked immunosorbant assay, immunohistochemistry, and Western blot analysis. Bone mineral density of the femur and lumbar vertebrae and biomechanical properties of the femur were decreased in CIA rats. Trabecular bone volume of the tibia and lumbar vertebrae was decreased whereas bone resorption was increased in CIA rats. Bone formation of the tibial shaft in periosteal surfaces was decreased in CIA rats. Furthermore, the trabecular bone loss in CIA rats was severer at 16 weeks than at 8 weeks, as was cortical bone loss. The serum level of tumor necrosis factor α in CIA rats was increased, and the expression of dickkopf 1 and that of receptor activator of nuclear factor κB (RANKL) ligand (RANKL) in the ankle joints were also increased, but the expression of osteoprotegerin (OPG) was decreased. We conclude that CIA rats developed systemic osteoporosis, and that osteoporosis became more serious with CIA development. The mechanism may be related to the increase of bone resorption in cancellous bone cause by upregulation of the expression of DKK-1 and regulation of the RANKL/RANK/OPG signaling pathway, and the decrease of bone formation in cortical bone caused by an increase in the expression of DKK-1.

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Background Cancer stem-like traits contribute to prostate cancer (PCa) progression and metastasis. Deciphering the novel molecular mechanisms underlying stem-like traits may provide important insight for developing novel therapeutics. Methods Immunohistochemistry and immunofluorescence assays in prostatic tissues; gain- and loss-of-function analyses using ectopic overexpression and shRNAs in PCa cell lines; measurements of tumorigenic and stemness properties, and transcription in vitro and in vivo; transcriptional analysis in public databases. Results We identified that overexpression of BTF3 in PCa tissues and BTF3 expression highly correlates to stem-like traits. Cancer stem-like characteristics in PCa including self-renewal and metastatic potential were impaired by BTF3 loss and promoted by BTF3 overexpression. Mechanistically, BTF3 could stabilize BMI1, which is a crucial regulator of prostate stem cell self-renewal. More importantly, our data revealed that BTF3 is highly predictive of poor prognosis and may help in risk stratification of PCa patients. Conclusions BTF3 promotes PCa progression though modeling stem-like traits in PCa. BTF3 represents a stratification marker in PCa progression and outcomes. Electronic supplementary material The online version of this article (10.1186/s13046-019-1222-z) contains supplementary material, which is available to authorized users.

Background: Castrate-resistant prostate cancer (CRPC) is an aggressive and lethal disease. The pathogenesis of CRPC is not fully understood and novel therapeutic targets need to be identified to improve the patients' prognosis. has been demonstrated to be a tumor suppressor in many types of solid malignancies. However, its role in androgen-independent (AI) growth of prostate cancer (PCa) received limited attention as yet. Methods:The clinical association of miR-30a and its potential targets with AI growth was characterized by bioinformatics analyses. Regulation of cell proliferation and colony formation rates by miR-30a were tested using PCa cell models. Xenograft models were used to measure the regulation of prostate tumor growth by miR-30a.The real-time quantitative polymerase chain reaction was used to validate whether miR-30a and its targets regulate cell cycle control genes and androgen receptor (AR)-dependent transcription. Bioinformatics tools, Western blot, and luciferase reporter assays were utilized to identify miR-30a targets. Results: Bioinformatic analysis showed that low expression of miR-30a is associated with castration resistance of PCa patients and poor outcomes. Transfection of miR-30a mimics inhibited the AI growth of PCa cells in vitro and in vivo. Upregulation of miR-30a in 22RV1 cells altered the expression of cell cycle control genes and AR-mediated transcription, while downregulation of miR-30a in LNCaP cells had the opposite effects to AR-mediated transcription. MYBL2, FOXD1, and SOX4 were identified as miR-30a targets. Downregulation of MYBL2, FOXD1, and SOX4 affected the expression of cell cycle control genes and AR-mediated transcription and suppressed the AI growth of 22RV1 cells. Conclusions: Our results suggest that miR-30a inhibits AI growth of PCa by targeting MYBL2, FOXD1, and SOX4. They provide novel insights into developing new treatment strategies for CRPC. K E Y W O R D S castration-resistant prostate cancer, FOXD1, miR-30a, MYBL2, SOX4