Exosomal PGAM1 promotes prostate cancer angiogenesis and metastasis by interacting with ACTG1.

Tumor-derived exosomes and their contents promote cancer metastasis. Phosphoglycerate mutase 1 (PGAM1) is involved in various cancer-related processes. Nevertheless, the underlying mechanism of exosomal PGAM1 in prostate cancer (PCa) metastasis remains unclear. In this study, we performed in vitro and in vivo to determine the functions of exosomal PGAM1 in the angiogenesis of patients with metastatic PCa. We performed Glutathione-S-transferase pulldown, co-immunoprecipitation, western blotting and gelatin degradation assays to determine the pathway mediating the effect of exosomal PGAM1 in PCa. Our results revealed a significant increase in exosomal PGAM1 levels in the plasma of patients with metastatic PCa compared to patients with non-metastatic PCa. Furthermore, PGAM1 was a key factor initiating PCa cell metastasis by promoting invadopodia formation and could be conveyed by exosomes from PCa cells to human umbilical vein endothelial cells (HUVECs). In addition, exosomal PGAM1 could bind to γ-actin (ACTG1), which promotes podosome formation and neovascular sprouting in HUVECs. In vivo results revealed exosomal PGAM1 enhanced lung metastasis in nude mice injected with PCa cells via the tail vein. In summary, exosomal PGAM1 promotes angiogenesis and could be used as a liquid biopsy marker for PCa metastasis.

CircSMARCC1 facilitates tumor progression by disrupting the crosstalk between prostate cancer cells and tumor-associated macrophages via miR-1322/CCL20/CCR6 signaling.

BACKGROUND: Circular RNAs (circRNAs) mediate the infiltration of tumor-associated macrophages (TAMs) to facilitate carcinogenesis and development of various types of cancers. However, the role of circRNAs in regulating macrophages in prostate cancer (PCa) remains uncertain. METHODS: Differentially expressed circRNAs in PCa were identified by RNA sequencing. The expression of circSMARCC1 was recognized and evaluated using fluorescence in situ hybridization and quantitative real-time PCR. The oncogenic role of circSMARCC1 in PCa tumor proliferation and metastasis was investigated through a series of in vitro and in vivo assays. Finally, Western blot, biotin-labeled RNA pulldown, luciferase assay, rescue experiments, and co-culture experiments with TAMs were conducted to reveal the mechanistic role of circSMARCC1. RESULTS: CircSMARCC1 was dramatically up-regulated in PCa cells, plasma and tissues. Overexpression of circSMARCC1 promotes tumor proliferation and metastasis both in vitro and in vivo, whereas knockdown of circSMARCC1 exerts the opposite effects. Mechanistically, circSMARCC1 regulates the expression of CC-chemokine ligand 20 (CCL20) via sponging miR-1322 and activate PI3K-Akt signaling pathway involved in the proliferation and epithelial mesenchymal transformation. More importantly, high expression of circSMARCC1 was positively associated with colonization of CD68+/CD163+/CD206+ TAMs in tumor microenvironment. In addition, overexpression of circSMARCC1 facilitates the expression of CD163 in macrophages through the CCL20-CCR6 axis, induces TAMs infiltration and M2 polarization, thereby leading to PCa progression. CONCLUSIONS: CircSMARCC1 up-regulates the chemokine CCL20 secretion by sponging miR-1322, which is involved in the crosstalk between tumor cells and TAMs by targeting CCL20/CCR6 signaling to promote progression of PCa.

Hsa_circ_0003258 promotes prostate cancer metastasis by complexing with IGF2BP3 and sponging miR-653-5p.

BACKGROUND: More and more studies have shown that circular RNAs (circRNAs) play a critical regulatory role in many cancers. However, the potential molecular mechanism of circRNAs in prostate cancer (PCa) remains largely unknown. METHODS: Differentially expressed circRNAs were identified by RNA sequencing. The expression of hsa_circ_0003258 was evaluated using quantitative real-time PCR and RNA in situ hybridization. The impacts of hsa_circ_0003258 on the metastasis of PCa cells were investigated by a series of in vitro and in vivo assays. Lastly, the underlying mechanism of hsa_circ_0003258 was revealed by Western blot, biotin-labeled RNA pulldown, RNA immunoprecipitation, luciferase assays and rescue experiments. RESULTS: Increased expression of hsa_circ_0003258 was found in PCa tissues and was associated with advanced TNM stage and ISUP grade. Overexpression of hsa_circ_0003258 promoted PCa cell migration by inducing epithelial mesenchymal transformation (EMT) in vitro as well as tumor metastasis in vivo, while knockdown of hsa_circ_0003258 exerts the opposite effect. Mechanistically, hsa_circ_0003258 could elevate the expression of Rho GTPase activating protein 5 (ARHGAP5) via sponging miR-653-5p. In addition, hsa_circ_0003258 physically binds to insulin like growth factor 2 mRNA binding protein 3 (IGF2BP3) in the cytoplasm and enhanced HDAC4 mRNA stability, in which it activates ERK signalling pathway, then triggers EMT programming and finally accelerates the metastasis of PCa. CONCLUSIONS: Upregulation of hsa_circ_0003258 drives tumor progression through both hsa_circ_0003258/miR-653-5p/ARHGAP5 axis and hsa_circ_0003258/IGF2BP3 /HDAC4 axis. Hsa_circ_0003258 may act as a promising biomarker for metastasis of PCa and an attractive target for PCa intervention.

SMARCC1 Suppresses Tumor Progression by Inhibiting the PI3K/AKT Signaling Pathway in Prostate Cancer.

BACKGROUND: SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin subfamily C member 1 (SMARCC1) protein is a potential tumor suppressor in various cancers. However, its role in prostate cancer (PCa) remains controversial. The aim of this study was to determine the biological function of SMARCC1 in PCa and explore the underlying regulatory mechanisms. METHODS: The expression of SMARCC1 was validated in PCa tissues by immunohistochemistry. Meanwhile, function experiments were used to evaluate the regulatory role on cell proliferation and metastasis in PCa cells with SMARCC1 depletion both in vitro and in vivo. The expression levels of relevant proteins were detected by Western blotting. RESULTS: Our finding showed that SMARCC1 was significantly downregulated in prostate adenocarcinoma, with a higher Gleason score (GS) than that in low GS. The decreased expression of SMARCC1 was significantly correlated with a higher GS and poor prognosis. Additionally, we found that silencing of SMARCC1 dramatically accelerated cell proliferation by promoting cell cycle progression and enhancing cell migration by inducing epithelial mesenchymal transition (EMT). Furthermore, depletion of SMARCC1 facilitated PCa xenograft growth and lung metastasis in murine models. Mechanistically, the loss of SMARCC1 activated the PI3K/AKT pathway in PCa cells. CONCLUSION: SMARCC1 suppresses PCa cell proliferation and metastasis via the PI3K/AKT signaling pathway and is a novel therapeutic target.

LncRNA SNHG1 and RNA binding protein hnRNPL form a complex and coregulate CDH1 to boost the growth and metastasis of prostate cancer.

The interaction between LncRNA and RNA-binding protein (RBPs) plays an essential role in the regulation over the malignant progression of tumors. Previous studies on the mechanism of SNHG1, an emerging lncRNA, have primarily focused on the competing endogenous RNA (ceRNA) mechanism. Nevertheless, the underlying mechanism between SNHG1 and RBPs in tumors remains to be explored, especially in prostate cancer (PCa). SNHG1 expression profiles in PCa were determined through the analysis of TCGA data and tissue microarray at the RNA level. Gain- and loss-of-function experiments were performed to investigate the biological role of SNHG1 in PCa initiation and progression. RNA-seq, immunoblotting, RNA pull-down and RNA immunoprecipitation analyses were utilized to clarify potential pathways with which SNHG1 might be involved. Finally, rescue experiments were carried out to further confirm this mechanism. We found that SNHG1 was dominantly expressed in the nuclei of PCa cells and significantly upregulated in PCa patients. The higher expression level of SNHG1 was dramatically correlated with tumor metastasis and patient survival. Functionally, overexpression of SNHG1 in PCa cells induced epithelial-mesenchymal transition (EMT), accompanied by down-regulation of the epithelial marker, E-cadherin, and up-regulation of the mesenchymal marker, vimentin. Increased proliferation and migration, as well as accelerated xenograft tumor growth, were observed in SNHG1-overexpressing PCa cells, while opposite effects were achieved in SNHG1-silenced cells. Mechanistically, SNHG1 competitively interacted with hnRNPL to impair the translation of protein E-cadherin, thus activating the effect of SNHG1 on the EMT pathway, eventually promoting the metastasis of PCa. Our findings demonstrate that SNHG1 is a positive regulator of EMT activation through the SNHG1-hnRNPL-CDH1 axis. SNHG1 may serve as a novel potential therapeutic target for PCa.

Phosphoribosyl pyrophosphate synthetases 2 knockdown inhibits prostate cancer progression by suppressing cell cycle and inducing cell apoptosis.

Phosphoribosyl pyrophosphate synthetases 2 (PRPS2) protein function as nucleotide synthesis enzyme that plays vital roles in cancer biology. However, the expression profile and function of PRPS2 in prostate cancer (PCa) remain to be identified. Here we investigated the expression of PRPS2 protein in human PCa and paired normal tissues by immunohistochemistry, meanwhile the regulatory effects on cell proliferation, apoptosis and growth of xenograft tumors in nude mice were evaluated in PCa cells with PRPS2 depletion. Moreover, the signaling pathways were also explored by western blot analysis and quantitative polymerase chain reaction assays. We found that PRPS2 was dramatically upregulated in prostate adenocarcinoma tissues in comparison with normal tissues, and that increased PRPS2 was linked intimately to advanced clinical stage and pT status. Functional experiments showed that knockdown of PRPS2 significantly suppressed cell growth both in vitro and in vivo. In addition, depletion of PRPS2 induced G1 phase cell cycle arrest and elevated cell apoptosis. Silencing of PRPS2 resulted in the decreased expression of Bcl­2 and cyclinD1 and increased levels of Bax, cleavage of caspases­3, caspases­9 and PARP. Furthermore, we also detected PRPS2 expression was significantly induced after DHT treatment, which implied the important role of PRPS2 in oncogenesis of PCa. Taken together, our findings elucidated that PRPS2 may be a potential novel candidate for PCa therapy.

HMGB1 Promotes Prostate Cancer Development and Metastasis by Interacting with Brahma-Related Gene 1 and Activating the Akt Signaling Pathway.

Background and Aim: We have previously shown that high-mobility group box 1 (HMGB1) is an independent biomarker for shortened survival of prostate cancer (PCa) patients. However, the specific role of HMGB1 in tumor development and progression remains largely unknown. In this study, we investigated the molecular mechanisms of HMGB1 in PCa tumorigenesis. Methods: Gain-of-function and loss-of-function experiments were used to determine the biological functions of HMGB1 both in vitro and in vivo. Bioinformatic analysis, immunoprecipitation, and immunofluorescence assays were applied to discern and examine the relationship between HMGB1 and its potential targets. Specimens from 64 patients with PCa were analyzed for the expression of HMGB1 and its relationship with Brahma-related gene 1 (BRG1) was examined by immunohistochemistry. Results: The results demonstrated that ectopic expression of HMGB1 facilitated growth and metastasis of PCa by enhancing Akt signaling pathway and promoting epithelial-mesenchymal transition (EMT), while silencing of HMGB1 showed the opposite effects. Mechanistically, HMGB1 exerted these functions through its interaction with BRG1 which may augment BRG1 function and activate the Akt signaling pathway thereby promoting EMT. Importantly, both HMGB1 and BRG1 expression was markedly increased in human PCa tissues. Conclusions: Taken together, these findings indicate that upregulation of HMGB1 promotes PCa development via activation of Akt and accelerates metastasis through regulating BRG1-mediated EMT. HMGB1 could be used as a novel potential target for the treatment of PCa.

Synthesis and biological evaluation of arylpiperazine derivatives as potential anti-prostate cancer agents.

A novel scaffold of arylpiperazine derivatives was discovered as potent androgen receptor (AR) antagonist through rational drug designation based on our pre-work, leading to the discovery of a series of new antiproliferative compounds. Compounds 10, 16, 27, 29 and 31 exhibited relatively strong antagonistic potency against AR and exhibited potent AR binding affinities, while compounds 5, 6, 10, 14, 16, 19, 21, 27 and 31 exhibited strong cytotoxic activities against LNCaP cells (AR-rich) as well as also displayed the higher activities than finasteride toward PC-3 (AR-deficient) and DU145 (AR-deficient). Docking study suggested that the most potent antagonist 16 mainly bind to AR ligand binding pocket (LBP) site through hydrogen bonding interactions. The structure-activity relationship (SAR) of these designed arylpiperazine derivatives was rationally explored and discussed. These results indicated that the novel scaffold compounds demonstrated a step towards the development of novel and improved AR antagonists, and promising candidates for future development were identified.

Downregulation of lncRNA PVT1 expression inhibits proliferation and migration by regulating p38 expression in prostate cancer.

Long non-coding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1) has been reported to be overexpressed in prostate cancer cells and associated with tumorigenesis in various types of cancer. However, the biological function of lncRNA PVT1 remains largely unknown. The aim of the present study was to investigate the effect of lncRNA PVT1 expression on the proliferation and migration of prostate cancer cells. Stably transfected prostate cancer cells with downregulated expression of lncRNA PVT1 were constructed by an efficient siRNA fragment, followed by confirmation by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Proliferation was assessed using CCK-8, colony formation and xenograft assays, and cell migration was evaluated using a wound healing assay. The PathScan® Intracellular Signaling Array kit was utilized to explore the underlying molecular mechanisms of lncRNA PVT1 expression in prostate cancer cells. RT-qPCR results confirmed that the lncRNA PVT1 expression level was successfully knocked down in prostate cancer cells. When lncRNA PVT1 expression was downregulated in prostate cancer cells, proliferation and migration were significantly inhibited, compared with the control lncRNA PVT1 group. Furthermore, PVT1 knockdown decreased the phosphorylation of p38 in DU145 cells. Therefore, the present study demonstrated that lncRNA PVT1 downregulation inhibits the proliferation and migration of prostate cancer cells, and is associated with p38 phosphorylation.

Suppressed epithelial-mesenchymal transition and cancer stem cell properties mediate the anti-cancer effects of ethyl pyruvate via regulation of the AKT/nuclear factor-κB pathway in prostate cancer cells.

Castration-resistant prostate cancer (CRPC) is a leading cause of mortality among cases of prostate cancer (PCa). Current treatment options for CRPC are limited. Ethyl pyruvate (EP), a lipophilic derivative of pyruvic acid, has been reported to have antitumor activities. In the present study, the efficacy of EP against PCa was investigated using two human PCa cell lines and a mouse xenograft tumor model. PC3 and CWR22RV1 cells were treated with EP, and cytotoxicity was evaluated via Cell Counting Kit-8 and colony formation assays, while cell cycle distribution was assessed by flow cytometry. Changes in cell migration and invasion caused by EP treatment were also evaluated with Transwell and wound healing assays, and changes in the expression of intracellular signaling pathway components were detected by western blotting. EP treatment reduced cell viability, induced G1 arrest, and activated the intrinsic apoptosis pathway. Additionally, the in vivo experiments revealed that EP administration markedly inhibited tumor growth. EP also reversed epithelial-mesenchymal transition and suppressed cancer stem cell properties in part through negative regulation of AKT/nuclear factor-κB signaling. These results indicate that EP has anticancer activity in vitro and in vivo, and is therefore a promising therapeutic agent for the treatment of PCa.

Phosphoglycerate mutase 1 knockdown inhibits prostate cancer cell growth, migration, and invasion.

Phosphoglycerate mutase 1 (PGAM1) is upregulated in many cancer types and involved in cell proliferation, migration, invasion, and apoptosis. However, the relationship between PGAM1 and prostate cancer is poorly understood. The present study investigated the changes in PGAM1 expression in prostate cancer tissues compared with normal prostate tissues and examined the cellular function of PGAM1 and its relationship with clinicopathological variables. Immunohistochemistry and Western blotting revealed that PGAM1 expression was upregulated in prostate cancer tissues and cell lines. PGAM1 expression was associated with Gleason score (P = 0.01) and T-stage (P = 0.009). Knockdown of PGAM1 by siRNA in PC-3 and 22Rv1 prostate cancer cell lines inhibited cell proliferation, migration, and invasion and enhanced cancer cell apoptosis. In a nude mouse xenograft model, PGAM1 knockdown markedly suppressed tumor growth. Deletion of PGAM1 resulted in decreased expression of Bcl-2, enhanced expression of Bax, caspases-3 and inhibition of MMP-2 and MMP-9 expression. Our results indicate that PGAM1 may play an important role in prostate cancer progression and aggressiveness, and that it might be a valuable marker of poor prognosis and a potential therapeutic target for prostate cancer.