Signaling Pathways In Prostate Cancer Research Articles

Supraphysiologic Testosterone Induces Ferroptosis and Activates Immune Pathways through Nucleophagy in Prostate Cancer.

The discovery that androgens play an important role in the progression of prostate cancer led to the development of androgen deprivation therapy (ADT) as a first line of treatment. However, paradoxical growth inhibition has been observed in a subset of prostate cancer upon administration of supraphysiologic levels of testosterone (SupraT), both experimentally and clinically. Here we report that SupraT activates cytoplasmic nucleic acid sensors and induces growth inhibition of SupraT-sensitive prostate cancer cells. This was initiated by the induction of two parallel autophagy-mediated processes, namely, ferritinophagy and nucleophagy. Consequently, autophagosomal DNA activated nucleic acid sensors converge on NFκB to drive immune signaling pathways. Chemokines and cytokines secreted by the tumor cells in response to SupraT resulted in increased migration of cytotoxic immune cells to tumor beds in xenograft models and patient tumors. Collectively, these findings indicate that SupraT may inhibit a subset of prostate cancer by activating nucleic acid sensors and downstream immune signaling. SIGNIFICANCE: This study demonstrates that supraphysiologic testosterone induces two parallel autophagy-mediated processes, ferritinophagy and nucleophagy, which then activate nucleic acid sensors to drive immune signaling pathways in prostate cancer.

Deoxynivalenol induces apoptosis and autophagy in human prostate epithelial cells via PI3K/Akt signaling pathway

Phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway is one of the most deregulated signaling pathway in prostate cancer. It controls basic processes in cells: cell proliferation and death. Any disturbances in the balance between cell death and survival might result in carcinogenesis. Deoxynivalenol (DON) is one of the most common mycotoxins, a toxic metabolites of fungi, present in our everyday diet and feed. Although previous studies reported DON to induce oxidative stress, modulate steroidogenesis, DNA damage and cell cycle modulation triggering together its toxicity, its effect on normal prostate epithelial cells is not known. The aim of the study was to evaluate the effect of DON on the apoptosis and autophagy in normal prostate epithelial cells via modulation of PI3K/Akt signaling pathway. The results showed that DON in a dose of 30 µM and 10 µM induces oxidative stress, DNA damage and cell cycle arrest in G2/M cell cycle phase. The higher concentration of DON induces apoptosis, whereas lower one autophagy in PNT1A cells, indicating that modulation of PI3K/Akt by DON results in the induction of autophagy triggering apoptosis in normal prostate epithelial cells.

HN1L promotes stem cell-like properties by regulating TGF-β signaling pathway through targeting FOXP2 in prostate cancer.

Dysregulated hematological and neurological expressed 1-like (HN1L) has been implicated in carcinogenesis of difference cancers, including hepatocellular carcinoma and breast cancer. However, the role of HN1L in the progression of prostate cancer (PCA) remains unknown. Therefore, we aimed to investigate the role of HN1L in stemness and progression of PCA. The expression of HN1L in PCA tissues and cells was determined by quantitative reverse-transcription polymerase chain reaction (qRT-PCR), western blot analysis, and/or immunohistochemistry (IHC). CD133+ cells were sorted from PCA cells using magnetic fluorescence cell sorting technology and were considered as cancer stem cells (CSCs). Sphere formation assays, transwell assays, and animal experiments were conducted to assess cell stemness, migration, invasion, and in vivo tumorigenesis, respectively. The results showed that HN1L expression was higher in PCA tissues and cells as compared with normal tissues and cells, as well as in CD133+ cells as compared with CD133- cells. HN1L knockdown significantly decreased the expression levels of CSC markers including OCT4 (POU class 5 homeobox 1), CD44, and SRY-box transcription factor 2, inhibited cell migration, invasion, and tumorigenesis and decreased the number of tumor spheroids and CD133+ cell population. Furthermore, we found that HN1L could bind to forkhead box P2 (FOXP2) and positively regulated transforming growth factor-β (TGF-β) expression via upregulation of FOXP2. In addition, the overexpression of TGF-β in HN1L-knockdown PCA cells increased the number of tumor spheroids and CD133+ cell population, as well as enhanced cell migration and invasion. Collectively, this study demonstrates that HN1L promotes stem cell-like properties and cancer progression by targeting FOXP2 through TGF-β signaling pathway in PCA.

Androgen Receptor and ETS-Like Protein-1 Expression of Prostate Cancer Correlates with Gleason Score International Society of Urological Pathology 2014/WHO 2016

AIM: Prostate cancer is the second most common and the fifth leading cause of death by cancer in men worldwide now. Grading based on Gleason score is a significant prognostic factor of prostate cancer. Androgen receptor (AR) plays important role in the initiation and progression of prostate cancer. AR signaling pathways in prostate cancer can also promote MAPK/ERK signaling pathways which activate ETS-like protein1 (Elk-1). METHODS: A total of 56 slides and paraffin blocks sampling of prostate cancer by consecutive from Department of Anatomical Pathology in West Sumatera. Hematoxylin and eosin (HE) stained slides were evaluated to review Gleason score, histopathological grading, and WHO grade group based on International Society of Urological Pathology (ISUP) 2014/WHO 2016. Immunohistochemistry staining of AR and Elk-1 was performed to analyze protein expression. RESULTS: Prostate cancers were found in mean age 70.68 ± 7.99 years. The most proportion of prostate cancer was Gleason score 9 (44.64%), histopathological grading poorly differentiated/undifferentiated (76.78%), and WHO grade Group 5 (48.21%). The positive expression AR of tumor cells 39 (69.64%) and Elk-1 34 (60.71%). Statistically, these results showed significant correlations of AR (p = 0.009) and Elk-1 (p = 0.012) with Gleason score. CONCLUSIONS: These results showed complex interactions between AR and Elk-1 initiation and progression of prostate cancer. Both variables indicated a significant correlation with Gleason score so that biomarkers prognostic potentially for prostate cancer.

MP33-04 HMGB1 PROMOTES TUMOR PROGRESSION AND INVASION THROUGH HMGB1/TNFR1/NF-ΚB AXIS IN CASTRATION-RESISTANT PROSTATE CANCER

You have accessJournal of UrologyProstate Cancer: Basic Research & Pathophysiology I (MP33)1 Sep 2021MP33-04 HMGB1 PROMOTES TUMOR PROGRESSION AND INVASION THROUGH HMGB1/TNFR1/NF-ΚB AXIS IN CASTRATION-RESISTANT PROSTATE CANCER Ae Ryang Jung, Yong Hyun Park, Dong Ho Shin, Hyong Woo Moon, U-Syn Ha, Sung-Hoo Hong, Ji Youl Lee, and Sae Woong Kim Ae Ryang JungAe Ryang Jung More articles by this author , Yong Hyun ParkYong Hyun Park More articles by this author , Dong Ho ShinDong Ho Shin More articles by this author , Hyong Woo MoonHyong Woo Moon More articles by this author , U-Syn HaU-Syn Ha More articles by this author , Sung-Hoo HongSung-Hoo Hong More articles by this author , Ji Youl LeeJi Youl Lee More articles by this author , and Sae Woong KimSae Woong Kim More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002042.04AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Prostate cancer (PCa) is the most common male cancer. Most patients treated with androgen deprivation therapy progress to castration-resistant PCa. To overcome the limitations of the current treatment, identification of more effective treatment targets is urgently needed. High mobility group box 1 protein (HMGB1) is known to be associated with progression, metastasis, and poor prognosis of several solid tumors; however, the role of HMGB1 in PCa remains unclear. Thus, we aimed to evaluate the clinical significance and biological mechanism of HMGB1 in PCa. METHODS: After transient transfection of PC3 and DU-145 cells with HMGB1 siRNA, diverse experiments were performed to evaluate the changes in proliferation, apoptosis, invasion. We subsequently investigated whether HMGB1 downregulation could affect NF-κB signaling in PCa cells using a human NF-κB proteome profiler array. To identify the TNFR responsible for HMGB1 binding, we performed a Co-IP assay on HEK293 cells following co-transfection with FLAG-HMGB1 and HA-TNFR1, 3, or 5. Finally, we determined the impact of HMGB1 on overall survival in PCa using the Cancer Genome Atlas (TCGA) datasets. We further validated the prognostic importance of HMGB1 by immunofluorescence staining in 131 PCa patients from the Korean Prostate Bank. RESULTS: The inhibition of HMGB1 expression significantly reduced cell proliferation, invasive capacity, and NF-κB signaling pathway in vitro. Our results showed that HMGB1 is a critical factor in the development and progression of PCa. Moreover, we found that HMGB1 directly interacts with TNFR1, and TNFR1 overexpression in HMGB1 knockdown cells reversed the effects of HMGB1 knockdown. In TCGA data set (n=498), HMGB1 was altered in 61 of 498 patients (12%). Overall survival was shorter in the high HMGB1 expression group (medians: 115.0 months vs. not reached; p=0.0296). In the Korean Prostate Bank cohort, the positive areas of HMGB1 differed in patients with BPH, and low-, intermediate-, high-risk, and metastatic PCa (4.6, 11.9, 18.6, 19.7, and 23.4%, p<0.001). During the median follow-up of 32 months, increased expression of HMGB1 was associated with a significant decrease in biochemical recurrence free survival on Kaplan-Meier analysis. CONCLUSIONS: Our results suggest that HMGB1 binding to TNFR1 promotes tumor progression by activating the NF-κB signaling pathway in PCa, and HMGB1/TNFR1/NF-κB signaling pathway could serve as a novel therapeutic target for improving PCa therapy. Source of Funding: None © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e607-e607 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ae Ryang Jung More articles by this author Yong Hyun Park More articles by this author Dong Ho Shin More articles by this author Hyong Woo Moon More articles by this author U-Syn Ha More articles by this author Sung-Hoo Hong More articles by this author Ji Youl Lee More articles by this author Sae Woong Kim More articles by this author Expand All Advertisement Loading ...

TACR2 is associated with the immune microenvironment and inhibits migration and proliferation via the Wnt/\u03b2-catenin signaling pathway in prostate cancer

BackgroundThe tachykinin receptor 2 (TACR2) is encoded by the tachykinin receptor correlation gene. Recent microarray analysis for prostate cancer suggests that TACR2 expression is associated with clinical phenotype and disease-free survival among patients with prostate cancer.ResultsTACR2 protein levels were lower in prostate cancer tissues than in adjacent normal prostate tissue. TACR2 expression significantly correlated with clinical stage, Gleason scores, and survival outcomes. TACR2 expression positively correlated with mast cells and negatively correlated with M2 macrophages. Overexpression of TACR2 promoted the migration and proliferation of prostate cancer cells by regulating the Wnt signaling pathway.ConclusionsThe TACR2-Wnt/β-catenin signaling pathway is critical in prostate cancer. TACR2 may affect tumor cells’ occurrence and development by changing the content of immune cells in the tumor microenvironment. These findings suggest that TACR2 may be a candidate molecular biomarker for prostate cancer therapy.

Abstract 2292: Tyrosine kinome profiling of renal cell carcinoma (RCC)

Abstract Background: Tyrosine kinase inhibitors (TKIs) constitute the backbone of treatment of metastatic (m) RCC. TKIs show great inter-individual variability of both efficacy and toxicity. The aim of this study was to compare the tyrosine kinase activity in normal and malignant kidney tissue and explore TKI effect on tumor tissue ex vivo. Materials and methods: Human nephrectomy samples (n = 295) consecutively collected at Akershus University Hospital from 2013 to 2019 were available. For this study, 22 samples of patients with mRCC (twenty-one clear cell and one chromophobe histology) and 3 with non-metastatic disease (two clear cell and one papillary histology) were selected. Tumor and normal tissue from each patient were prepared and assessed by an experienced pathologist, and 5µg of protein lysates was extracted. Kinase activity profiling of 144 tyrosine kinase peptides was performed using PamChip Arrays for PAMSTATION12. Protein lysates from tumors were in addition treated with four different TKIs ex vivo, based on IC50; sunitinib (2.5 µM), cabozantinib (2.5 µM), pazopanib (10 µM) and tivozanib (2 µM). All data was processed and analyzed in Bionavigator V.6 (PamGene). Results: The overall tyrosine kinase activity was increased in tumor tissue compared to normal tissue in all samples. The activity of 36 tyrosine kinases differed significantly (FDR &amp;lt; 0.05), with 20 kinases showing higher and 16 showing lower phosphorylation in tumor compared to normal tissue. Furthermore, adding TKIs to tumor samples ex vivo revealed different potencies of the TKIs. Tivozanib and cabozantinib showed higher inhibition potency compared to sunitinib and pazopanib. Two well-defined peptide clusters were especially affected by tivozanib and cabozantinib exposure. Compared to untreated tumor tissue, the activity of 29 kinases including common TKI targets MET, EGFR, PDGFR and FGFR was significantly reduced in cluster 1. However, we also identified reduced activity of several other kinases i.e. RB, CDK2, CLB, CAM, ZAP70 and PDK1 involved in RAS, RAP1, PI3K-AKT and prostate cancer signaling pathways. In cluster 2, 21 kinases showed increased activity upon TKI exposure, amongst them JNK, ERK, erbB1/erbB2, Shp2 and PLCγ involved in MAPK, ERBB and proteoglycans signaling pathways, and possibly accounting for subsequent TKI resistance. Conclusion: Kinase activity differs significantly between malignant and normal kidney tissue. Furthermore, we have demonstrated different inhibitory effects of TKIs ex-vivo and identified two peptide clusters significantly affected by TKI. Further analysis of affected kinases and signaling pathways as well as correlations with clinical data for the same group of patients will be performed. To our knowledge, similar systematic comprehensive analysis of tyrosine kinase activity and correlation to clinical data has not been reported previously. Citation Format: Katarina Puco, Andliena Tahiri, Faris Naji, Daniel Heinrich, Vessela N. Kristenssen, Glenny C. Alfsen, Lorant Farkas, Frode S. Nilsen, Stig Müller, Jan Oldenburg, Jürgen Geisler. Tyrosine kinome profiling of renal cell carcinoma (RCC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2292.

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

BackgroundSWI/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.MethodsThe 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.ResultsOur 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.ConclusionSMARCC1 suppresses PCa cell proliferation and metastasis via the PI3K/AKT signaling pathway and is a novel therapeutic target.

GDI2 is a target of paclitaxel that affects tumorigenesis of prostate cancer via the p75NTR signaling pathway

BackgroundProstate cancer (PCa) refers to malignant tumors derived from prostate epithelial cells, whose morbidity and mortality rates have been increasing every year. Although new drugs for treating prostate cancer continue to emerge, the unclear mechanism underlying drug targets limits this therapy, thereby constraining identification of effective therapeutic targets. Although GDP dissociation inhibitor 2(GDI2) is highly expressed and closely associated with occurrence and development of many tumors, its role in prostate cancer remains unclear. In this study, we investigated the role of GDI2 and elucidated its underlying mechanism of action in prostate cancer. Moreover, we screened chemotherapeutic drugs that affect GDI2 expression with a view of identifying novel targets for diagnosis and treatment of prostate cancer. MethodsWe performed sequence analyses and functional assays to precisely elucidate the GDI2 role in prostate cancer. Moreover, we induced tumorigenesis in nude mice to verify the role of GDI2 in vivo. Finally, we used the CCK8 assay to ascertain the most suitable IC50 across the three drugs and performed quantitative real time polymerase chain reaction (qRT-PCR) and Western Blot to analyze the effects of drugs on expression of GDI2, p75NTR, and p-NFκB. ResultsGDI2 was up-regulated in prostate cancer cells and tissues. Knocking down GDI2 suppressed cell proliferation but promoted cell apoptosis. Interestingly, knocking down GDI2 activated the p75NTR signaling pathway, indicating, for the first time, that p75NTR is negatively correlated with GDI2 expression. ConclusionTaken together, these results indicate that GDI2 is a therapeutic target of paclitaxel. Knocking down of GDI2 inhibits cell proliferation and promotes cell apoptosis via the p75NTR signaling pathway in prostate cancer. Notably, paclitaxel inhibits GDI2 expression, implying that GDI2 may be a promising therapeutic target in prostate cancer.

The antiandrogenic effect of neferine, liensinine, and isoliensinine by inhibiting 5-α-reductase and androgen receptor expression via PI3K/AKT signaling pathway in prostate cancer.

Neferine, liensinine, and isoliensinine are bisbenzylisoquinoline alkaloids extracted from seed-embryos of Nelumbo nucifera Gaertn. In this study, we evaluated the anticancer activities and mechanism of action of these natural products in prostate cancer cells by MTT, wound healing, ELISA and Western blotting. Neferine, liensinine, and isoliensinine showed growth inhibition and displayed a significant anti-migration activity in prostate cancer cells. They induced apoptosis and autophagy by activating cleaved caspase-9, cleaved PAPR, Bax, LC3B-II, but decreased Bcl-2 and PARP protein expression in LNCaP cells 24 h after treatments. The apoptotic and cytotoxic effects of neferine, liensinine, and isoliensinine were significantly attenuated in the presence of the caspase inhibitor, Z-VAD-FMK. However, the effects were enhanced in the presence of Akt inhibitor (MK2206) and PI3K inhibitor (LY294002). Moreover, neferine, liensinine, and isoliensinine also downregulated the protein expression of androgen receptor, prostate-specific antigen, and type II 5-α-reductase. These results demonstrated that these bisbenzylisoquinoline alkaloids have the potential as promising therapeutics agents. They induced apoptosis via inactivation with the PI3K/AKT signal pathway.

CNTN-1 promotes docetaxel resistance and epithelial-to-mesenchymal transition via the PI3K/Akt signaling pathway in prostate cancer.

IntroductionTherapy options for prostate cancer (PCa) typically are centered on docetaxel-based chemotherapy but are limited by the effects of multi-drug resistance. Recent advances have illustrated a role of contactin-1 (CNTN-1) in tumor chemoresistance, while the function and mechanism of CNTN-1 in the resistance of docetaxel in prostate cancer have not yet been elucidated.Material and methodsDocetaxel (Dox)-resistant PCa cell lines of PC3 (PC3-DR) and DU145 (DU145-DR) were established, and short hairpin RNA (shRNA) constructs targeting CNTN-1 were generated to analyze the effect of knockdown of CNTN-1 on PCa progression. Cell Counting Kit-8 (CCK-8), flow cytometry, wound-healing, transwell and western blotting analysis were used to analyze cell proliferation, apoptosis, migration, invasion and related protein expression levels, respectively.ResultsKnockdown of CNTN-1 in PC3-DR and DU145-DR cells attenuated cell proliferation, migration, invasion, EMT phenotype, and drug resistance, and increased cell apoptosis further reduced the tumorigenic phenotype. Knockdown of CNTN-1 resulted in an anti-tumor effect in the xenograft tumor model, and decreased activity of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway both in vitro and in vivo.ConclusionsThe results of the present study suggest that downregulation of CNTN-1 may be an important mechanism to reverse chemoresistance in Dox-resistant PCa progression, thus shedding light on the development of novel anti-tumor therapeutics for the treatment of PCa.

Androgen Receptor Signaling Pathway in Prostate Cancer: From Genetics to Clinical Applications

Around 80–90% of prostate cancer (PCa) cases are dependent on androgens at initial diagnosis; hence, androgen ablation therapy directed toward a reduction in serum androgens and the inhibition of androgen receptor (AR) is generally the first therapy adopted. However, the patient’s response to androgen ablation therapy is variable, and 20–30% of PCa cases become castration resistant (CRPCa). Several mechanisms can guide treatment resistance to anti-AR molecules. In this regard, AR-dependent and -independent resistance mechanisms can be distinguished within the AR pathway. In this article, we investigate the multitude of AR signaling aspects, encompassing the biological structure of AR, current AR-targeted therapies, mechanisms driving resistance to AR, and AR crosstalk with other pathways, in an attempt to provide a comprehensive review for the PCa research community. We also summarize the new anti-AR drugs approved in non-metastatic castration-resistant PCa, in the castration-sensitive setting, and combination therapies with other drugs.

Abstract 4361: A systematic study of the impact of estrogens and selective estrogen receptor modulators on prostate cancer cell proliferation

Abstract The estrogen receptors ERα and ERβ are expressed in prostate cancer (PCa) cells and are believed to act as an oncogene and a tumor suppressor, respectively, and thus to be attractive therapeutic targets. Indeed, compounds modulating the activity of these receptors already exist and are currently used to treat ERα-positive breast tumors. However, there is a lot of discrepancies regarding the efficacy of anti-estrogen treatments for the management of PCa. Several factors explain these discrepancies, including unspecific antibodies against ERβ, lack of proper estrogenic positive controls, and usage of estrogens and anti-estrogens molecules at high dosages were off-target effects are observed. Our objective was to conduct a systematic study on the impact of estrogenic and anti-estrogenic ligands on PCa cell proliferation and survival. After optimization of our cellular assay using the human breast cancer cell line MCF7, we used five of the most commonly studied human PCa cell models, namely LNCaP, 22Rv1, LAPC4, DU145, and PC3 cells. These cells were treated with nine estrogenic/anti-estrogenic compounds, including five selective estrogen receptor modulators (SERMs), with and without co-treatment with androgens for androgen receptor (AR)-positive cells. In both AR-positive and AR-negative cells, we observed no significant modulation of proliferation following modulation of ERs activity. Using both RNA-seq and Western Blots, ERs expression was mostly undetectable in these models. Our study indicate that commonly used PCa models in vitro are not appropriate models to study the estrogen signaling pathway in PCa. Yet, expression data from PCa tissues indicate a significant expression of both receptors, and indicate that usage of new PCa models or of in vivo models are required to properly study drug repurposing of anti-estrogens and SERMs for PCa treatment. Citation Format: Camille Lafront, Lucas Germain, Cindy Weidmann, Etienne Audet-Walsh. A systematic study of the impact of estrogens and selective estrogen receptor modulators on prostate cancer cell proliferation [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4361.

Long non-coding RNA CCAT2 promotes prostate cancer cell proliferation and invasion by regulating the Wnt/β-catenin signaling pathway.

Long non-coding RNA colon cancer associated transcript 2 (CCAT2) is dysregulated in a number of different types of human cancer, and affects cancer progression via the Wnt/β-catenin signaling pathway. However, the roles of CCAT2 and the Wnt/β-catenin signaling pathway in prostate cancer (PCa) are not completely understood. The present study aimed to investigate the potential mechanism of CCAT2 in PCa. In the present study, the reverse transcription-quantitative PCR (RT-qPCR) results indicated that CCAT2 expression was significantly upregulated in PCa tissues, and DU145 and PC3 cell lines compared with normal prostate tissues and the epithelial RWPE-1 cell line, respectively. Functional assays indicated that CCAT2 downregulation inhibited DU145 and PC3 cell proliferation, cell cycle, migration and invasion. In addition, the luciferase reporter assay, RT-qPCR and western blotting results indicated that CCAT2 regulated transcription factor 7 like 2 (TCF7L2) expression by binding to microRNA-217. Further western blotting and TOPFlash assays indicated that CCAT2-knockdown inhibited the Wnt/β-catenin signaling pathway in DU145 and PC3 cell lines by inhibiting the expression of TCF7L2. However, CCAT2-knockdown-mediated effects were reversed by the Wnt/β-catenin signaling pathway activator lithium chloride (LiCl). Further cell experiments suggested that LiCl treatment reversed CCAT2-knockdown-mediated inhibition of PCa cell proliferation, cell cycle, epithelial-mesenchymal transition, migration and invasion. Overall, the results indicated that CCAT2 regulated PCa via the Wnt/β-catenin signaling pathway; therefore, CCAT2 may exhibit key role during the progression of PCa and may serve as a therapeutic target for the disease.

Rapamycin inhibits AR signaling pathway in prostate cancer by interacting with the FK1 domain of FKBP51

Reactivation of the androgen receptor signaling pathway in the emasculated environment is the main reason for the occurrence of castration-resistant prostate cancer (CRPC). The immunophilin FKBP51, as a co-chaperone protein, together with Hsp90 help the correct folding of AR. Rapamycin is a known small-molecule inhibitor of FKBP51, but its effect on the FKBP51/AR signaling pathway is not clear. In this study, the interaction mechanism between FKBP51 and rapamycin was investigated using steady-state fluorescence quenching, X-ray crystallization, MTT assay, and qRT-PCR. Steady-state fluorescence quenching assay showed that rapamycin could interact with FKBP51. The crystal of the rapamycin-FKBP51 complex indicated that rapamycin occupies the hydrophobic binding pocket of FK1 domain which is vital for AR activity. The residues involving rapamycin binding are mainly hydrophobic and may overlap with the AR interaction site. Further assays showed that rapamycin could inhibit the androgen-dependent growth of human prostate cancer cells by down-regulating the expression levels of AR activated downstream genes. Taken together, our study demonstrates that rapamycin suppresses AR signaling pathway by interfering with the interaction between AR and FKBP51. The results of this study not only can provide useful information about the interaction mechanism between rapamycin and FKBP51, but also can provide new clues for the treatment of prostate cancer and castration-resistant prostate cancer.

Independence of HIF1a and androgen signaling pathways in prostate cancer

BackgroundTherapeutic targeting of the androgen signaling pathway is a mainstay treatment for prostate cancer. Although initially effective, resistance to androgen targeted therapies develops followed by disease progression to castrate-resistant prostate cancer (CRPC). Hypoxia and HIF1a have been implicated in the development of resistance to androgen targeted therapies and progression to CRCP. The interplay between the androgen and hypoxia/HIF1a signaling axes was investigated.MethodsIn vitro stable expression of HIF1a was established in the LNCaP cell line by physiological induction or retroviral transduction. Tumor xenografts with stable expression of HIF1a were established in castrated and non-castrated mouse models. Gene expression analysis identified transcriptional changes in response to androgen treatment, hypoxia and HIF1a. The binding sites of the AR and HIF transcription factors were identified using ChIP-seq.ResultsAndrogen and HIF1a signaling promoted proliferation in vitro and enhanced tumor growth in vivo. The stable expression of HIF1a in vivo restored tumor growth in the absence of endogenous androgens. Hypoxia reduced AR binding sites whereas HIF binding sites were increased with androgen treatment under hypoxia. Gene expression analysis identified seven genes that were upregulated both by AR and HIF1a, of which six were prognostic.ConclusionsThe oncogenic AR, hypoxia and HIF1a pathways support prostate cancer development through independent signaling pathways and transcriptomic profiles. AR and hypoxia/HIF1a signaling pathways independently promote prostate cancer progression and therapeutic targeting of both pathways simultaneously is warranted.

Suppression of cathepsin a inhibits growth, migration, and invasion by inhibiting the p38 MAPK signaling pathway in prostate cancer

Prostate cancer has the highest incidence among men in advanced countries, as well as a high mortality rate. Despite the efforts of numerous researchers to identify a gene-based therapeutic target as an effective treatment of prostate cancer, there is still a need for further research. The cathepsin gene family is known to have a close correlation with various cancer types and is highly expressed across these cancer types. This study aimed at investigating the correlation between the cathepsin A (CTSA) gene and prostate cancer. Our findings indicated a significantly elevated level of CTSA gene expression in the tissues of patients with prostate cancer when compared with normal prostate tissues. Furthermore, the knockdown of the CTSA gene in the representative prostate cancer cell lines PC3 and DU145 led to reduced proliferation and a marked reduction in anchorage-independent colony formation, which was shown to be caused by cell cycle arrest in the S phase. In addition, CTSA gene-knockdown prostate cancer cell lines showed a substantial decrease in migration and invasion, as well as a decrease in the marker genes that promote epithelial mesenchymal transition (EMT). Such phenotypic changes in prostate cancer cell lines through CTSA gene suppression were found to be mainly caused by reduced p38 MAPK protein phosphorylation; i.e. the inactivation of the p38 MAPK cell signaling pathway. Tumorigenesis was also found to be inhibited in CTSA gene-knockdown prostate cancer cell lines when a xenograft assay was carried out using Balb/c nude mice, and the p38 MAPK phosphorylation was inhibited in tumor tissues. Thus, the CTSA gene is presumed to play a key role in human prostate cancer tissues through high-level expression, and the suppression of the CTSA gene leads to the inhibition of prostate cancer cell proliferation, colony formation, and metastasis. The mechanism, by which these effects occur, was demonstrated to be the inactivation of the p38 MAPK signaling pathway.

Multifaceted Function of MicroRNA-299-3p Fosters an Antitumor Environment Through Modulation of Androgen Receptor and VEGFA Signaling Pathways in Prostate Cancer

Prostate cancer (PCa) is one of the most common cancers to affect men worldwide. Androgen receptor (AR) signaling is central to PCa and PCa therapy. MicroRNAs (miRNAs) play crucial roles in the regulation of prostate cancer through modulation of signaling pathways. In the present study, we illustrate the functional significance and therapeutic benefit of miR-299-3p, an AR targeting microRNA, in PCa progression. We noted loss of expression of miR-299-3p in prostate tumors compared to noncancerous prostate tissues. Replenishment of miR-299-3p in C4-2B, 22Rv-1 and PC-3 cells contributed to cell cycle arrest, reduced proliferation, migration and increased expression of apoptotic markers. Additionally, overexpression of miR-299-3p induced a reduction of AR, PSA and VEGFA expression. AGO-RNA pulldown experiment showed enrichment of AR, VEGFA and miR-299-3p in C4-2B cells overexpressing miR-299-3p. miR-299-3p overexpression also inhibited epithelial mesenchymal transition, expression of Slug, TGF-β3, phospho-AKT and phospho-PRAS40, but increased expression of E-cadherin. Furthermore, miR-299 overexpression resulted in reduced tumor growth in xenograft models and increased drug sensitivity. Overall, this study has identified novel mechanisms of antitumor and antimigration function of miR-299-3p through modulation of AR and VEGFA signaling pathways which lead to improved drug sensitivity of PCa.

A Systematic Study of the Impact of Estrogens and Selective Estrogen Receptor Modulators on Prostate Cancer Cell Proliferation

The estrogen signaling pathway has been reported to modulate prostate cancer (PCa) progression through the activity of estrogen receptors α and β (ERα and ERβ). Given that selective estrogen receptor modulators (SERMs) are used to treat breast cancer, ERs have been proposed as attractive therapeutic targets in PCa. However, many inconsistencies regarding the expression of ERs and the efficacy of SERMs for PCa treatment exist, notably due to the use of ERβ antibodies lacking specificity and treatments with high SERM concentrations leading to off-target effects. To end this confusion, our objective was to study the impact of estrogenic and anti-estrogenic ligands in well-studied in vitro PCa models with appropriate controls, dosages, and ER subtype-specific antibodies. When using physiologically relevant concentrations of nine estrogenic/anti-estrogenic compounds, including five SERMs, we observed no significant modulation of PCa cell proliferation. Using RNA-seq and validated antibodies, we demonstrate that these PCa models do not express ERs. In contrast, RNA-seq from PCa samples from patients have detectable expression of ERα. Overall, our study reveals that commonly used PCa models are inappropriate to study ERs and indicate that usage of alternative models is essential to properly assess the roles of the estrogen signaling pathway in PCa.

Advances of Zinc Signaling Studies in Prostate Cancer.

Prostate cancer (PCa) is one of the most common cancers and the second leading cause of cancer-related death among men worldwide. Despite progresses in early diagnosis and therapeutic strategies, prognosis for patients with advanced PCa remains poor. Noteworthily, a unique feature of healthy prostate is its highest level of zinc content among all soft tissues in the human body, which dramatically decreases during prostate tumorigenesis. To date, several reviews have suggested antitumor activities of zinc and its potential as a therapeutic strategy of PCa. However, an overview about the role of zinc and its signaling in PCa is needed. Here, we review literature related to the content, biological function, compounds and clinical application of zinc in PCa. We first summarize zinc content in prostate tissue and sera of PCa patients with their clinical relevance. We then elaborate biological functions of zinc signaling in PCa on three main aspects, including cell proliferation, death and tumor metastasis. Finally, we discuss clinical applications of zinc-containing compounds and proteins involved in PCa signaling pathways. Based on currently available studies, we conclude that zinc plays a tumor suppressive role and can serve as a biomarker in PCa diagnosis and therapies.