MAP Kinases and Prostate Cancer

Design, synthesis, molecular docking and biological evaluation of 1,3,5-trisubstituted-1H-pyrazole derivatives as anticancer agents with cell cycle arrest, ERK and RIPK3- kinase activities

The need for new ERK and RIPK3 kinase modulators arises from their central roles in cellular processes, especially in diseases like cancer. This research focused on a ligand-based strategy, incorporating previously documented 1,3,5-trisubstituted-1H-pyrazole derivatives, to craft innovative inhibitors specifically targeting ERK and RIPK3 kinases. Compounds 6, 7, 10a, 10c, and 10d exhibited significant cytotoxicity against PC-3 and MCF-7 cancer cell lines, with IC50 values ranging from 21.9 to 28.6 µM and 3.90-35.5 µM, respectively values surpassing those of the reference compound Doxorubicin. Additionally, cell cycle analysis revealed intriguing results, particularly with 10d inducing cell cycle arrest at the S phase in treated PC-3 cells, indicating potential DNA replication phase inhibition. Moreover, compounds 6, 10a, and 10d exhibited promising results in the in vitro kinase assay supported by molecular docking studies. The core scaffold of these compounds established interactions with vital amino acids within the active pockets of ERK and RIPK3 kinases, thereby securely anchoring them in place. These findings underscore the development of promising modulators for ERK and RIPK3 kinases, suggesting their potential for future contributions to cancer treatments.

HIRA-mediated loading of histone variant H3.3 controls androgen-induced transcription by regulation of AR/BRD4 complex assembly at enhancers

Incorporation of histone variant H3.3 comprises active territories of chromatin. Exploring the function of H3.3 in prostate cancer (PC), we found that knockout (KO) of H3.3 chaperone HIRA suppresses PC growth in vitro and in xenograft settings, deregulates androgen-induced gene expression and alters androgen receptor (AR) binding within enhancers of target genes. H3.3 affects transcription in multiple ways, including activation of p300 by phosphorylated H3.3 at Ser-31 (H3.3S31Ph), which results in H3K27 acetylation (H3K27Ac) at enhancers. In turn, H3K27Ac recruits bromodomain protein BRD4 for enhancer-promoter interaction and transcription activation. We observed that HIRA KO reduces H3.3 incorporation, diminishes H3.3S31Ph and H3K27Ac, modifies recruitment of BRD4. These results suggest that H3.3-enriched enhancer chromatin serves as a platform for H3K27Ac-mediated BRD4 recruitment, which interacts with and retains AR at enhancers, resulting in transcription reprogramming. In addition, HIRA KO deregulates glucocorticoid- (GR) driven transcription of genes co-regulated by AR and GR, suggesting a common H3.3/HIRA-dependent mechanism of nuclear receptors function. Expression of HIRA complex proteins is increased in PC compared with normal prostate tissue, especially in high-risk PC groups, and is associated with a negative prognosis. Collectively, our results demonstrate function of HIRA-dependent H3.3 pathway in regulation of nuclear receptors activity.

Elucidation of scandenolone as anti-cancer activity through impairment of the metabolic and signaling vulnerabilities in prostate cancer

Prostate cancer (PCa) is the most prevalent men's cancer in America and Western countries. No effective therapies are currently available for PCa aggressiveness, including castration-resistant progression (CRPC). This study aims at evaluation of the prospective efficacy and the molecular mechanism of scandenolone (SCA), a natural isoflavone, in PCa progression. SCA suppressed cell viability and progression and induced apoptosis in PCa cells. SCA inhibited the expression of lipogenesis and cholesterogenesis related key genes. Through inhibition of these metabolic genes, SCA decreased the levels of fatty acids, lipid droplets and cholesterols in PCa cells. Moreover, SCA enhanced the expression of antioxidant factors, including Nrf2, HO-1, catalase and SOD-1, and reduced the ROS levels in PCa cells. Substantially, SCA displayed the potential efficacy on CRPC tumors. This paper offers a new insight into the underlying molecular basis of SCA in PCa cells. By coordinated impairment of the metabolic and signaling vulnerabilities, including lipogenesis, cholesterogenesis, ROS and the AR/PSA axis, SCA could be applied as a novel and promising remedy to cure malignant PCa.

Asiatic acid exhibits antimetastatic activity in human prostate cancer cells by modulating the MZF-1/Elk-1/Snail signaling axis

Prostate cancer metastasis is associated with poor prognosis and is difficult to treat clinically. Numerous studies have shown that Asiatic Acid (AA) has antibacterial, anti-inflammatory, and antioxidant effects. However, the effect of AA on prostate cancer metastasis is still unclear. This purpose of this study is to investigate the effect of AA on prostate cancer metastasis and to better understand its molecular mechanisms of action. Our results indicate that AA ≤ 30 μM did not influence cell viability and cell cycle distribution in PC3, 22Rv1 and DU145 cells. AA inhibited the migratory and invasive capabilities of three prostate cancer cells to be due to its effects on Snail, but did not have activity on Slug. We observed that AA inhibited the Myeloid zinc finger 1 (MZF-1) and ETS Like-1 (Elk-1) protein interaction and affected the complex's binding capacity to the Snail promoter region, ultimately blocking Snail transcription activity. Kinase cascade analysis revealed that phosphorylation of MEK3/6 and p38MAPK was inhibited by AA treatment. Moreover, knockdown of p38MAPK enhanced AA-suppressed protein levels of MZF-1, Elk-1, and Snail, suggesting that p38MAPK influences prostate cancer cell metastasis. These results provide promise for AA as a future candidate in the development of drug therapies to prevent or treat prostate cancer metastasis.

A comparative mRNA- and miRNA transcriptomics reveals novel molecular signatures associated with metastatic prostate cancers

Background: Prostate cancer (PC) is a fatally aggressive urogenital cancer killing millions of men, globally. Thus, this study aims to identify key miRNAs, target genes, and drug targets associated with prostate cancer metastasis.

Methods: The miRNA and mRNA expression datasets of 148 prostate tissue biopsies (39 tumours and 109 normal tissues), were analysed by differential gene expression analysis, protein interactome mapping, biological pathway analysis, miRNA-mRNA networking, drug target analysis, and survival curve analysis.

Results: The dysregulated expression of 53 miRNAs and their 250 target genes involved in Hedgehog, ErbB, and cAMP signalling pathways connected to cell growth, migration, and proliferation of prostate cancer cells was detected. The subsequent miRNA-mRNA network and expression status analysis have helped us in narrowing down their number to 3 hub miRNAs (hsa-miR-455-3p, hsa-miR-548c-3p, and hsa-miR-582-5p) and 9 hub genes (NFIB, DICER1, GSK3B, DCAF7, FGFR1OP, ABHD2, NACC2, NR3C1, and FGF2). Further investigations with different systems biology methods have prioritized NR3C1, ABHD2, and GSK3B as potential genes involved in prostate cancer metastasis owing to their high mutation load and expression status. Interestingly, down regulation of NR3C1 seems to improve the prostate cancer patient survival rate beyond 150 months. The NR3C1, ABHD2, and GSK3B genes are predicted to be targeted by hsa-miR-582-5p, besides some antibodies, PROTACs and inhibitory molecules.

Conclusion: This study identified key miRNAs (miR-548c-3p and miR-582-5p) and target genes (NR3C1, ABHD2, and GSK3B) as potential biomarkers for metastatic prostate cancers from large-scale gene expression data using systems biology approaches.

Cytotoxic N-Methylpretrichodermamide B Reveals Anticancer Activity and Inhibits P-Glycoprotein in Drug-Resistant Prostate Cancer Cells

N-methylpretrichodermamide B (NB) is a biologically active epidithiodiketopiperazine isolated from several strains of the algae-derived fungus Penicillium sp. Recently, we reported the first data on its activity in human cancer cells lines in vitro. Here, we investigated the activity, selectivity, and mechanism of action of NB in human prostate cancer cell lines, including drug-resistant subtypes. NB did not reveal cross-resistance to docetaxel in the PC3-DR cell line model and was highly active in hormone-independent 22Rv1 cells. NB-induced cell death was stipulated by externalization of phosphatidylserine and activation of caspase-3. Moreover, inhibition of caspase activity by z-VAD(OMe)-fmk did not affect NB cytotoxicity, suggesting a caspase-independent cell death induced by NB. The compound has a moderate p-glycoprotein (p-gp) substrate-like affinity and can simultaneously inhibit p-gp at nanomolar concentrations. Therefore, NB resensitized p-gp-overexpressing PC3-DR cells to docetaxel. A kinome profiling of the NB-treated cells revealed, among other things, an induction of mitogen-activated protein kinases JNK1/2 and p38. Further functional analysis confirmed an activation of both kinases and indicated a prosurvival role of this biological event in the cellular response to the treatment. Overall, NB holds promising anticancer potential and further structure-activity relationship studies and structural optimization are needed in order to improve its biological properties.

Combinatorial approaches of nanotherapeutics for inflammatory pathway targeted therapy of prostate cancer

Prostate cancer (PC) is the most prevalent male urogenital cancer worldwide. PC patients presenting an advanced or metastatic cancer succumb to the disease, even after therapeutic interventions including radiotherapy, surgery, androgen deprivation therapy (ADT), and chemotherapy. One of the hallmarks of PC is evading immune surveillance and chronic inflammation, which is a major challenge towards designing effective therapeutic formulations against PC. Chronic inflammation in PC is often characterized by tumor microenvironment alterations, epithelial-mesenchymal transition and extracellular matrix modifications. The inflammatory events are modulated by reactive nitrogen and oxygen species, inflammatory cytokines and chemokines. Major signaling pathways in PC includes androgen receptor, PI3K and NF-κB pathways and targeting these inter-linked pathways poses a major therapeutic challenge. Notably, many conventional treatments are clinically unsuccessful, due to lack of targetability and poor bioavailability of the therapeutics, untoward toxicity and multidrug resistance. The past decade witnessed an advancement of nanotechnology as an excellent therapeutic paradigm for PC therapy. Modern nanovectorization strategies such as stimuli-responsive and active PC targeting carriers offer controlled release patterns and superior anti-cancer effects. The current review initially describes the classification, inflammatory triggers and major inflammatory pathways of PC, various PC treatment strategies and their limitations. Subsequently, recent advancement in combinatorial nanotherapeutic approaches, which target PC inflammatory pathways, and the mechanism of action are discussed. Besides, the current clinical status and prospects of PC homing nanovectorization, and major challenges to be addressed towards the advancement PC therapy are also addressed.

Acridone Derivatives from Atalantia monophyla Inhibited Cancer Cell Proliferation through ERK Pathway

The present study aimed to investigate the effect of acridone alkaloids on cancer cell lines and elucidate the underlying molecular mechanisms. The ten acridone alkaloids from Atalantia monophyla were screened for cytotoxicity against LNCaP cell lines by a WST-8 assay. Then, the most potential acridone, buxifoliadine E, was evaluated on four types of cancer cells, namely prostate cancer (LNCaP), neuroblastoma (SH SY5Y), hepatoblastoma (HepG2), and colorectal cancer (HT29). The results showed that buxifoliadine E was able to significantly inhibit the proliferation of all four types of cancer cells, having the most potent cytotoxicity against the HepG2 cell line. Western blotting analysis was performed to assess the expression of signaling proteins in the cancer cells. In HepG2 cells, buxifoliadine E induced changes in the levels of Bid as well as cleaved caspase-3 and Bax through MAPKs, including Erk and p38. Moreover, the binding interaction between buxifoliadine E and Erk was investigated by using the Autodock 4.2.6 and Discovery Studio programs. The result showed that buxifoliadine E bound at the ATP-binding site, located at the interface between the N- and C-terminal lobes of Erk2. The results of this study indicate that buxifoliadine E suppressed cancer cell proliferation by inhibiting the Erk pathway.

Protein signatures to distinguish aggressive from indolent prostate cancer

BACKGROUND

Distinguishing men with aggressive from indolent prostate cancer is critical to decisions in the management of clinically localized prostate cancer. Molecular signatures of aggressive disease could help men overcome this major clinical challenge by reducing unnecessary treatment and allowing more appropriate treatment of aggressive disease.

METHODS

We performed a mass spectrometry-based proteomic analysis of normal and malignant prostate tissues from 22 men who underwent surgery for prostate cancer. Prostate cancer samples included Grade Groups (3-5), with 8 patients experiencing recurrence and 14 without evidence of recurrence with a mean of 6.8 years of follow-up. To better understand the biological pathways underlying prostate cancer aggressiveness, we performed a systems biology analysis and gene enrichment analysis. Proteins that distinguished recurrent from nonrecurrent cancer were chosen for validation by immunohistochemical analysis on tissue microarrays containing samples from a larger cohort of patients with recurrent and nonrecurrent prostate cancer.

RESULTS

In all, 24,037 unique peptides (false discovery rate < 1%) corresponding to 3,313 distinct proteins were identified with absolute abundance ranges spanning seven orders of magnitude. Of these proteins, 115 showed significantly (p < 0.01) different levels in tissues from recurrent versus nonrecurrent cancers. Analysis of all differentially expressed proteins in recurrent and nonrecurrent cases identified several protein networks, most prominently one in which approximately 24% of the proteins in the network were regulated by the YY1 transcription factor (adjusted p < 0.001). Strong immunohistochemical staining levels of three differentially expressed proteins, POSTN, CALR, and CTSD, on a tissue microarray validated their association with shorter patient survival.

CONCLUSIONS

The protein signatures identified could improve understanding of the molecular drivers of aggressive prostate cancer and be used as candidate prognostic biomarkers.

Nimbolide inhibits 2D and 3D prostate cancer cells migration, affects microtubules and angiogenesis and suppresses B-RAF/p.ERK-mediated in vivo tumor growth

BACKGROUND

Prostate cancer (PCa) is the most prominent malignancy among men worldwide. PCa cells have a high tendency to metastasize to various distant organs, and this activity is the main cause of PCa mortality. Nimbolide is a promising phytochemical constituent of neem Azadirachta indica (Meliaceae). Previous studies showed that nimbolide exhibited potent anticancer activity however, its role against PCa tumorigenesis has not been fully elucidated.

PURPOSE

Our work aims to explore the role of nimbolide in regulating the essential tumor-associated processes involved in the metastatic cascade in PCa cells.

STUDY DESIGN

Cytotoxicity assay, wound healing and spheroid invasion assays, western blotting, immunofluorescence, tube-formation assay, in vivo and immunohistochemistry.

METHODS

The cytotoxicity of nimbolide towards PCa cell lines was assessed by resazurin assays. The cell mobility and migration of nimbolide-treated DU145 cells were determined by wound healing and spheroid invasion assays. Tubulin network was visualized using U2OS cells and DU145 cells. The effect of nimbolide on E-cadherin, β-catenin, acetylated α-tubulin and HDAC6 protein expressions levels were measured by Western blot. The potentiality of nimbolide to inhibit angiogenesis was revealed by HUVEC tube-formation assay. Nimbolide antitumor effect was studied in a syngeneic model of murine prostate cancer.

RESULTS

The current study indicated that nimbolide negatively affected the migratory and invasive capacity of DU145 prostate cancer cells in 2D and three-dimensional (3D) spheroid cultures. Interestingly, nimbolide induced downregulation of E-cadherin without any influence on the expression level of β-catenin. Additionally, we demonstrated that nimbolide influenced the microtubule network which was supported by the upregulation of acetylated α-tubulin and the reduction in HDAC6 protein. Moreover, the inhibitory effect of nimbolide on angiogenesis was clearly observed in HUVEC tube formation assay. In vivo experiments revealed the significant suppression of PCa growth and targeting of the B-RAF/p.ERK signaling pathway by nimbolide.

CONCLUSION

Our results showed that nimbolide inhibited 2D and 3D prostate cancer cells migration and downregulated E-cadherin protein expression, a marker for metastatic chemoresistance and tumor recurrence. Nimbolide stabilized the microtubules, combated angiogenesis and suppressed B.RAF/ERK-mediated in vivo tumor growth. Nimbolide may be considered as potential therapeutic agent for metastatic and advanced PCa patients and merits further investigations.

Exploring the Value of BRD9 as a Biomarker, Therapeutic Target and Co-Target in Prostate Cancer

Background and aims: Despite recent advances in advanced prostate cancer treatments, clinical biomarkers or treatments for men with such cancers are imperfect. Targeted therapies have shown promise, but there remain fewer actionable targets in prostate cancer than in other cancers. This work aims to characterise BRD9, currently understudied in prostate cancer, and investigate its co-expression with other genes to assess its potential as a biomarker and therapeutic target in human prostate cancer. Materials and methods: Omics data from a total of 2053 prostate cancer patients across 11 independent datasets were accessed via Cancertool and cBioPortal. mRNA M.expression and co-expression, mutations, amplifications, and deletions were assessed with respect to key clinical parameters including survival, Gleason grade, stage, progression, and treatment. Network and pathway analysis was carried out using Genemania, and heatmaps were constructed using Morpheus. Results: BRD9 is overexpressed in prostate cancer patients, especially those with metastatic disease. BRD9 expression did not differ in patients treated with second generation antiandrogens versus those who were not. BRD9 is co-expressed with many genes in the SWI/SNF and BET complexes, as well as those in common signalling pathways in prostate cancer. Summary and conclusions: BRD9 has potential as a diagnostic and prognostic biomarker in prostate cancer. BRD9 also shows promise as a therapeutic target, particularly in advanced prostate cancer, and as a co-target alongside other genes in the SWI/SNF and BET complexes, and those in common prostate cancer signalling pathways. These promising results highlight the need for wider experimental inhibition and co-targeted inhibition of BRD9 in vitro and in vivo, to build on the limited inhibition data available.

Polyphenols as Antitumor Agents Targeting Key Players in Cancer-Driving Signaling Pathways

Polyphenols constitute an important group of natural products that are traditionally associated with a wide range of bioactivities. These are usually found in low concentrations in natural products and are now available in nutraceuticals or dietary supplements. A group of polyphenols that include apigenin, quercetin, curcumin, resveratrol, EGCG, and kaempferol have been shown to regulate signaling pathways that are central for cancer development, progression, and metastasis. Here, we describe novel mechanistic insights on the effect of this group of polyphenols on key elements of the signaling pathways impacting cancer. We describe the protein modifications induced by these polyphenols and their effect on the central elements of several signaling pathways including PI3K, Akt, mTOR, RAS, and MAPK and particularly those affecting the tumor suppressor p53 protein. Modifications of p53 induced by these polyphenols regulate p53 gene expression and protein levels and posttranslational modifications such as phosphorylation, acetylation, and ubiquitination that influence stability, subcellular location, activation of new transcriptional targets, and the role of p53 in response to DNA damage, apoptosis control, cell- cycle regulation, senescence, and cell fate. Thus, deep understanding of the effects that polyphenols have on these key players in cancer-driving signaling pathways will certainly lead to better designed targeted therapies, with less toxicity for cancer treatment. The scope of this review centers on the regulation of key elements of cancer signaling pathways by the most studied polyphenols and highlights the importance of a profound understanding of these regulations in order to improve cancer treatment and control with natural products.

Coexpression network analysis identified lncRNAs-mRNAs with potential relevance in African ancestry prostate cancer

AIM

This study aims to investigate similarities and differences using lncRNA and mRNA coexpression network analysis in African ancestry (AA) and European ancestry (EA) among prostate cancer (PCa) patients.

METHODS

We performed weighted gene coexpression network analysis of the expression from 49 of AA and 49 of EA to identify lncRNAs-mRNAs.

RESULTS

27 lncRNAs and 36 mRNAs were highly expressed in patients of AA. Two mRNAs and their antisense lncRNAs were expressed. Additionally, seven mRNAs were DE or coexpressed and had an impact on survival.

CONCLUSION

We present a list of lncRNAs and mRNAs that were DE and coexpressed when comparing patients of AA and EA, and these data are a resource for future studies to understand the role of lncRNAs.

Modulation of cell physiology under hypoxia in pancreatic cancer

In solid tumors, the development of vasculature is, to some extent, slower than the proliferation of the different types of cells that form the tissue, both cancer and stroma cells. As a consequence, the oxygen availability is compromised and the tissue evolves toward a condition of hypoxia. The presence of hypoxia is variable depending on where the cells are localized, being less extreme at the periphery of the tumor and more severe in areas located deep within the tumor mass. Surprisingly, the cells do not die. Intracellular pathways that are critical for cell fate such as endoplasmic reticulum stress, apoptosis, autophagy, and others are all involved in cellular responses to the low oxygen availability and are orchestrated by hypoxia-inducible factor. Oxidative stress and inflammation are critical conditions that develop under hypoxia. Together with changes in cellular bioenergetics, all contribute to cell survival. Moreover, cell-to-cell interaction is established within the tumor such that cancer cells and the microenvironment maintain a bidirectional communication. Additionally, the release of extracellular vesicles, or exosomes, represents short and long loops that can convey important information regarding invasion and metastasis. As a result, the tumor grows and its malignancy increases. Currently, one of the most lethal tumors is pancreatic cancer. This paper reviews the most recent advances in the knowledge of how cells grow in a pancreatic tumor by adapting to hypoxia. Unmasking the physiological processes that help the tumor increase its size and their regulation will be of major relevance for the treatment of this deadly tumor.

Host versus cell-dependent effects of β-arrestin 1 expression in prostate tumorigenesis

Prostate cancer (PCa) constitutes a serious health challenge and remains one of the main causes of cancer-related death among men. The more aggressive form of the disease has been attributed to androgen independence, resulting in a lack of response to androgen deprivation therapy and sustained activation of other growth pathways. The scaffold proteins β-arrestin 1 and 2 (βarr1 and βarr2), which are known to mediate G protein-coupled receptor desensitization and internalization, were also shown to modulate prostate tumorigenesis. βarr1 is significantly overexpressed (>4-fold) in PCa cells relative to βarr2. In this study, we investigated the effect of βarr1 overexpression in PCa development and progression using the mouse and human PCa cell xenografts, and autochthonous transgenic adenocarcinoma of the mouse prostate (TRAMP) models deficient in β-arrestin depletion of βarr1 in TRAMP mice (TRAMP/βarr1-/-) increased PCa growth and decreased overall survival relative to control TRAMP or TRAMP/βarr2-/- animals. Prostate tissues from TRAMP/βarr1-/- tumors displayed an increase in androgen receptor (AR) expression, whereas overexpression of βarr1 in TRAMP-C1 (TRAMP-C1-βarr1-GFP) which derived from TRAMP decreased AR expression, cell proliferation and tumor growth in nude mice xenografts, relative to control TRAMP-C1-GFP. Knockdown of βarr1 expression in human MDA PCa 2b cells (MDA PCa 2b-βarr1-/-) also decreased AR expression cell proliferation and tumor growth relative to control (MDA PCa 2b-Sham) cells. Interestingly, both TRAMP-C1-βarr1-GFP and MDA PCa 2b-βarr1-/- xenografts showed a decrease in AKT phosphorylation but an increase in MAPK activation. Altogether, the data indicate that the effect of βarr1 in modulating AR signaling to regulate PCa aggressiveness is cell and host autonomous.

Signaling Pathways That Control Apoptosis in Prostate Cancer

Prostate cancer is the second most common malignancy and the fifth leading cancer-caused death in men worldwide. Therapies that target the androgen receptor axis induce apoptosis in normal prostates and provide temporary relief for advanced disease, yet prostate cancer that acquired androgen independence (so called castration-resistant prostate cancer, CRPC) invariably progresses to lethal disease. There is accumulating evidence that androgen receptor signaling do not regulate apoptosis and proliferation in prostate epithelial cells in a cell-autonomous fashion. Instead, androgen receptor activation in stroma compartments induces expression of unknown paracrine factors that maintain homeostasis of the prostate epithelium. This paradigm calls for new studies to identify paracrine factors and signaling pathways that control the survival of normal epithelial cells and to determine which apoptosis regulatory molecules are targeted by these pathways. This review summarizes the recent progress in understanding the mechanism of apoptosis induced by androgen ablation in prostate epithelial cells with emphasis on the roles of BCL-2 family proteins and "druggable" signaling pathways that control these proteins. A summary of the clinical trials of inhibitors of anti-apoptotic signaling pathways is also provided. Evidently, better knowledge of the apoptosis regulation in prostate epithelial cells is needed to understand mechanisms of androgen-independence and implement life-extending therapies for CRPC.

Efficacy and Mechanism of Action of Marine Alkaloid 3,10-Dibromofascaplysin in Drug-Resistant Prostate Cancer Cells

Efficacy and mechanism of action of marine alkaloid 3,10-dibromofascaplysin (DBF) were investigated in human prostate cancer (PCa) cells harboring different levels of drug resistance. Anticancer activity was observed across all cell lines examined without signs of cross-resistance to androgen receptor targeting agents (ARTA) or taxane based chemotherapy. Kinome analysis followed by functional investigation identified JNK1/2 to be one of the molecular targets of DBF in 22Rv1 cells. In contrast, no activation of p38 and ERK1/2 MAPKs was observed. Inhibition of the drug-induced JNK1/2 activation or of the basal p38 activity resulted in increased cytotoxicity of DBF, whereas an active ERK1/2 was identified to be important for anticancer activity of the alkaloid. Synergistic effects of DBF were observed in combination with PARP-inhibitor olaparib most likely due to the induction of ROS production by the marine alkaloid. In addition, DBF intensified effects of platinum-based drugs cisplatin and carboplatin, and taxane derivatives docetaxel and cabazitaxel. Finally, DBF inhibited AR-signaling and resensitized AR-V7-positive 22Rv1 prostate cancer cells to enzalutamide, presumably due to AR-V7 down-regulation. These findings propose DBF to be a promising novel drug candidate for the treatment of human PCa regardless of resistance to standard therapy.

Activation of overexpressed glucagon-like peptide-1 receptor attenuates prostate cancer growth by inhibiting cell cycle progression

AIMS/INTRODUCTION

Incretin therapy is a common treatment for type 2 diabetes mellitus. We have previously reported an anti-prostate cancer effect of glucagon-like peptide-1 receptor (GLP-1R) agonist exendin-4. The attenuation of cell proliferation in the prostate cancer cell line was dependent on GLP-1R expression. Here, we examined the relationship between human prostate cancer severity and GLP-1R expression, as well as the effect of forced expression of GLP-1R using a lentiviral vector.

MATERIALS AND METHODS

Prostate cancer tissues were extracted by prostatectomy and biopsy. GLP-1R was overexpressed in ALVA-41 cells using a lentiviral vector (ALVA-41-GLP-1R cells). GLP-1R expression was detected by immunohistochemistry and quantitative polymerase chain reaction. Cell proliferation was examined by growth curves and bromodeoxyuridine incorporation assays. Cell cycle distribution and regulators were examined by flow cytometry and western blotting. In vivo experiments were carried out using a xenografted model.

RESULTS

GLP-1R expression levels were significantly inversely associated with the Gleason score of human prostate cancer tissues. Abundant GLP-1R expression and functions were confirmed in ALVA-41-GLP-1R cells. Exendin-4 significantly decreased ALVA-41-GLP-1R cell proliferation in a dose-dependent manner. DNA synthesis and G1-to-S phase transition were inhibited in ALVA-41-GLP-1R cells. SKP2 expression was decreased and p27Kip1 protein was subsequently increased in ALVA-41-GLP-1R cells treated with exendin-4. In vivo experiments carried out by implanting ALVA-41-GLP-1R cells showed that exendin-4 decreased prostate cancer growth by activation of GLP-1R overexpressed in ALVA41-GLP-1R cells.

CONCLUSIONS

Forced expression of GLP-1R attenuates prostate cancer cell proliferation by inhibiting cell cycle progression in vitro and in vivo. Therefore, GLP-1R activation might be a potential therapy for prostate cancer.

Genome-wide gene expression analysis of a murine model of prostate cancer progression: Deciphering the roles of IL-6 and p38 MAPK as potential therapeutic targets

BACKGROUND

Prostate cancer (PCa) is the most commonly diagnosed cancer and the second leading cause of cancer-related deaths among adult males globally. The poor prognosis of PCa is largely due to late diagnosis of the disease when it has already progressed to an advanced stage marked by androgen-independence, thus necessitating new strategies for early detection and treatment. We construe that these direly needed advances are limited by our poor understanding of early events in the progression of PCa and that would thus represent ideal targets for early intervention. To begin to fill this void, we interrogated molecular "oncophenotypes" that embody the transition of PCa from an androgen-dependent (AD) to-independent (AI) state.

METHODS

To accomplish this aim, we used our previously established AD and AI murine PCa cell lines, PLum-AD and PLum-AI, respectively, which recapitulate primary and progressive PCa morphologically and molecularly. We statistically surveyed global gene expressions in these cell lines by microarray analysis. Differential profiles were functionally interrogated by pathways, gene set enrichment and topological gene network analyses.

RESULTS

Gene expression analysis of PLum-AD and PLum-AI transcriptomes (n = 3 each), revealed 723 differentially expressed genes (392 upregulated and 331 downregulated) in PLum-AI compared to PLum-AD cells. Gene set analysis demonstrated enrichment of biological functions and pathways in PLum-AI cells that are central to tumor aggressiveness including cell migration and invasion facilitated by epithelial-to-mesenchymal transition (EMT). Further analysis demonstrated that the p38 mitogen-activated protein kinase (MAPK) was predicted to be significantly activated in the PLum-AI cells, whereas gene sets previously associated with favorable response to the p38 inhibitor SB203580 were attenuated (i.e., inversely enriched) in the PLum-AI cells, suggesting that these aggressive cells may be therapeutically vulnerable to p38 inhibition. Gene set and gene-network analysis also alluded to activation of other signaling networks particularly those associated with enhanced EMT, inflammation and immune function/response including, but not limited to Tnf, IL-6, Mmp 2, Ctgf, and Ptges. Accordingly, we chose SB203580 and IL-6 to validate their effect on PLum-AD and PLum-AI. Some of the common genes identified in the gene-network analysis were validated at the molecular and functional level. Additionally, the vulnerability to SB203580 and the effect of IL-6 were also validated on the stem/progenitor cell population using the sphere formation assay.

CONCLUSIONS

In summary, our study highlights pathways associated with an augmented malignant phenotype in AI cells and presents new high-potential targets to constrain the aggressive malignancy seen in the castration-resistant PCa.

miR-137-3p Modulates the Progression of Prostate Cancer by Regulating the JNK3/EZH2 Axis

Background

Prostate cancer (PCa) is one of the most common cancers in men worldwide. Early detection of prostate cancer by prostate-specific antigen (PSA) screening still has limitations. The discovery of new candidates is urgent and can provide insights into the mechanism involved in prostate cancer tumorigenesis.

Methods

We conducted a cross-sectional study involving prostate cancer cell lines and clinical samples. qPCR and IHC were used to evaluate the expression of miR-137-3p/JNK3/EZH2. Furthermore, cell growth, migration, invasion, cell cycle and apoptosis were analyzed to describe the function of this axis. Moreover, xenograft models, pathology platforms and TCGA data were generated to confirm the role of the miR-137-3p/JNK3/EZH2 axis.

Results

In this study, we determined that miR-137-3p was significantly reduced in prostate cancer, and low expression of miR-137-3p was correlated with tumor stage . The overexpression of miR-137-3p suppressed cell proliferation, migration and invasion in prostate cancer by enhancing cell apoptosis. We also validated JNK3 (MAPK10) as a direct target gene of miR-137-3p. Down-regulation of JNK3 in prostate cancer also inhibited cell proliferation and invasion and promoted apoptosis. Moreover, JNK3 expression was up-regulated and negatively correlated with miR-137-3p in prostate cancer tissues. Furthermore, JNK3 modulated EZH2 expression, which is a key oncogene in prostate cancer. Survival data indicated that patients with high levels of JNK3 and EZH2 had a worse prognosis.

Conclusion

Collectively, the identification of miR-137-3p and the JNK3/EZH2 pathway might facilitate the development of biomarkers and therapeutic targets for prostate cancer.

Marine alkaloid monanchoxymycalin C: a new specific activator of JNK1/2 kinase with anticancer properties

Monanchoxymycalin C (MomC) is a new marine pentacyclic guanidine alkaloid, recently isolated from marine sponge Monanchora pulchra by us. Here, anticancer activity and mechanism of action was investigated for the first time using a human prostate cancer (PCa) model. MomC was active in all PCa cell lines at low micromolar concentrations and induced an unusual caspase-independent, non-apoptotic cell death. Kinase activity screening identified activation of mitogen-activated protein kinase (MAPK) c-Jun N-terminal protein kinase (JNK1/2) to be one of the primary molecular mechanism of MomC anticancer activity. Functional assays demonstrated a specific and selective JNK1/2 activation prior to the induction of other cell death related processes. Inhibition of JNK1/2 by pretreatment with the JNK-inhibitor SP600125 antagonized cytotoxic activity of the marine compound. MomC caused an upregulation of cytotoxic ROS. However, in contrast to other ROS-inducing agents, co-treatment with PARP-inhibitor olaparib revealed antagonistic effects indicating an active PARP to be necessary for MomC activity. Interestingly, although no direct regulation of p38 and ERK1/2 were detected, active p38 kinase was required for MomC efficacy, while the inhibition of ERK1/2 increased its cytotoxicity. In conclusion, MomC shows promising activity against PCa, which is exerted via JNK1/2 activation and non-apoptotic cell death.

Unique targeting of androgen-dependent and -independent AR signaling in prostate cancer to overcome androgen resistance

The androgen receptor (AR) is a major driver of prostate cancer (PCa) and a key therapeutic target for AR inhibitors (ie, Enzalutamide). However, Enzalutamide only inhibits androgen-dependent AR signaling, enabling intrinsic AR activation via androgen-independent pathways, leading to aggressive castration-resistant PCa (CRPC). We investigated the ability of novel anti-cancer agents, Dp44mT and DpC, to overcome androgen resistance. The effect of Dp44mT and DpC on androgen-dependent and independent AR signaling was assessed in androgen-dependent and -independent PCa cells using 2D- and 3D-tissue culture. The clinically trialed DpC was then examined in vivo and compared to Enzalutamide. These agents uniquely promote AR proteasomal degradation and inhibit AR transcription in PCa cells via the upregulation of c-Jun, potently reducing the AR target, prostate-specific antigen (PSA). These agents also inhibited the activation of key molecules in both androgen-dependent and independent AR signaling (ie, EGFR, MAPK, PI3K), which promote CRPC. The clinically trialed DpC also significantly inhibited PCa tumor growth, AR, and PSA expression in vivo, being more potent than Enzalutamide. DpC is a promising candidate for a unique, structurally distinct generation of AR inhibitors that simultaneously target both androgen-dependent and independent arms of AR signaling. No other therapies exhibit such comprehensive and potent AR suppression, which is critical for overcoming the development of androgen resistance.

Identification of candidate miRNAs in early-onset and late-onset prostate cancer by network analysis

The incidence of patients under 55 years old diagnosed with Prostate Cancer (EO-PCa) has increased during recent years. The molecular biology of PCa cancer in this group of patients remains unclear. Here, we applied weighted gene coexpression network analysis of the expression of miRNAs from 24 EO-PCa patients (38–45 years) and 25 late-onset PCa patients (LO-PCa, 71–74 years) to identify key miRNAs in EO-PCa patients. In total, 69 differentially expressed miRNAs were identified. Specifically, 26 and 14 miRNAs were exclusively deregulated in young and elderly patients, respectively, and 29 miRNAs were shared. We identified 20 hub miRNAs for the network built for EO-PCa. Six of these hub miRNAs exhibited prognostic significance in relapse‐free or overall survival. Additionally, two of the hub miRNAs were coexpressed with mRNAs of genes previously identified as deregulated in EO-PCa and in the most aggressive forms of PCa in African-American patients compared with Caucasian patients. These genes are involved in activation of immune response pathways, increased rates of metastasis and poor prognosis in PCa patients. In conclusion, our analysis identified miRNAs that are potentially important in the molecular pathology of EO-PCa. These genes may serve as biomarkers in EO-PCa and as possible therapeutic targets.

Activator of G protein signaling 3 modulates prostate tumor development and progression

Prostate cancer (PCa) is a leading cause of cancer death among men, with greater prevalence of the disease among the African American population in the USA. Activator of G-protein signaling 3 (AGS3/G-protein signaling modulator 1) was shown to be overexpressed in prostate adenocarcinoma relative to the prostate gland. In this study, we investigated the correlation between AGS3 overexpression and PCa malignancy. Immunoblotting analysis and real-time quantitative-PCR showed increase in AGS3 expression in the metastatic cell lines LNCaP (~3-fold), MDA PCa 2b (~2-fold), DU 145 (~2-fold) and TRAMP-C1 (~20-fold) but not in PC3 (~1-fold), relative to control RWPE-1. Overexpression of AGS3 in PC3, LNCaP and MDA PCa 2b enhanced tumor growth. AGS3 contains seven tetratricopeptide repeats (TPR) and four G-protein regulatory (GPR) motifs. Overexpression of the TPR or the GPR motifs in PC3 cells had no effect in tumor growth. Depletion of AGS3 in the TRAMP-C1 cells (TRAMP-C1-AGS3-/-) decreased cell proliferation and delayed wound healing and tumor growth in both C57BL/6 (~3-fold) and nude mice xenografts, relative to control TRAMP-C1 cells. TRAMP-C1-AGS3-/- tumors also exhibited a marked increase (~5-fold) in both extracellular signal-regulated kinase (ERK) 1/2 and P38 mitogen-activated protein kinase (MAPK) activation, which correlated with a significant increase (~3-fold) in androgen receptor (AR) expression, relative to TRAMP-C1 xenografts. Interestingly, overexpression of AGS3 in TRAMP-C1-AGS3-/- cells inhibited ERK activation and AR overexpression as compared with control TRAMP-C1 cells. Taken together, the data indicate that the effect of AGS3 in prostate cancer development and progression is probably mediated via a MAPK/AR-dependent pathway.

Ras and Wnt Interaction Contribute in Prostate Cancer Bone Metastasis

Prostate cancer (PCa) is one of the most prevalent and malignant cancer types in men, which causes more than three-hundred thousand cancer death each year. At late stage of PCa progression, bone marrow is the most often metastatic site that constitutes almost 70% of metastatic cases of the PCa population. However, the characteristic for the osteo-philic property of PCa is still puzzling. Recent studies reported that the Wnt and Ras signaling pathways are pivotal in bone metastasis and that take parts in different cytological changes, but their crosstalk is not well studied. In this review, we focused on interactions between the Wnt and Ras signaling pathways during each stage of bone metastasis and present the fate of those interactions. This review contributes insights that can guide other researchers by unveiling more details with regard to bone metastasis and might also help in finding potential therapeutic regimens for preventing PCa bone metastasis.

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.

The Prospect of Identifying Resistance Mechanisms for Castrate-Resistant Prostate Cancer Using Circulating Tumor Cells: Is Epithelial-to-Mesenchymal Transition a Key Player?

Prostate cancer (PCa) is initially driven by excessive androgen receptor (AR) signaling with androgen deprivation therapy (ADT) being a major therapeutic approach to its treatment. However, the development of drug resistance is a significant limitation on the effectiveness of both first-line and more recently developed second-line ADTs. There is a need then to study AR signaling within the context of other oncogenic signaling pathways that likely mediate this resistance. This review focuses on interactions between AR signaling, the well-known phosphatidylinositol-3-kinase/AKT pathway, and an emerging mediator of these pathways, the Hippo/YAP1 axis in metastatic castrate-resistant PCa, and their involvement in the regulation of epithelial-mesenchymal transition (EMT), a feature of disease progression and ADT resistance. Analysis of these pathways in circulating tumor cells (CTCs) may provide an opportunity to evaluate their utility as biomarkers and address their importance in the development of resistance to current ADT with potential to guide future therapies.

The molecular function of kallikrein-related peptidase 14 demonstrates a key modulatory role in advanced prostate cancer

Kallikrein-related peptidase 14 (KLK14) is one of the several secreted KLK serine proteases involved in prostate cancer (PCa) pathogenesis. While relatively understudied, recent reports have identified KLK14 as overexpressed during PCa development. However, the modulation of KLK14 expression during PCa progression and the molecular and biological functions of this protease in the prostate tumor microenvironment remain unknown. To determine the modulation of KLK14 expression during PCa progression, we analyzed the expression levels of KLK14 in patient samples using publicly available databases and immunohistochemistry. In order to delineate the molecular mechanisms involving KLK14 in PCa progression, we integrated proteomic, transcriptomic, and in vitro assays with the goal to identify substrates, related-signaling pathways, and functional roles of this protease. We showed that KLK14 expression is elevated in advanced PCa, and particularly in metastasis. Additionally, KLK14 levels were found to be decreased in PCa tissues from patients responsive to neoadjuvant therapy compared to untreated patients. Furthermore, we also identified that KLK14 expression reoccurred in patients who developed castrate-resistant PCa. The combination of proteomic and transcriptomic analysis as well as functional assays revealed several new KLK14 substrates (agrin, desmoglein 2, vitronectin, laminins) and KLK14-regulated genes (Interleukin 32, midkine, SRY-Box 9), particularly an involvement of the mitogen-activated protein kinase 1 and interleukin 1 receptor pathways, and an involvement of KLK14 in the regulation of cellular migration, supporting its involvement in aggressive features of PCa progression. In conclusion, our work showed that KLK14 expression is associated with the development of aggressive PCa suggesting that targeting this protease could offer a novel route to limit the progression of prostate tumors. Additional work is necessary to determine the benefits and implications of targeting/cotargeting KLK14 in PCa as well as to determine the potential use of KLK14 expression as a predictor of PCa aggressiveness or response to treatment.

Proteomics Analysis of Formalin Fixed Paraffin Embedded Tissues in the Investigation of Prostate Cancer

Prostate cancer (PCa) is one of the leading causes of death in men worldwide. The molecular features, associated with the onset and progression of the disease, are under vigorous investigation. Formalin-fixed paraffin-embedded (FFPE) tissues are valuable resources for large-scale studies; however, their application in proteomics is limited due to protein cross-linking. In this study, the adjustment of a protocol for the proteomic analysis of FFPE tissues was performed which was followed by a pilot application on FFPE PCa clinical samples to investigate whether the optimized protocol can provide biologically relevant data for the investigation of PCa. For the optimization, FFPE mouse tissues were processed using seven protein extraction protocols including combinations of homogenization methods (beads, sonication, boiling) and buffers (SDS based and urea-thiourea based). The proteome extraction efficacy was then evaluated based on protein identifications and reproducibility using SDS electrophoresis and high resolution LC-MS/MS analysis. Comparison between the FFPE and matched fresh frozen (FF) tissues, using an optimized protocol involving protein extraction with an SDS-based buffer following beads homogenization and boiling, showed a substantial overlap in protein identifications with a strong correlation in relative abundances (r_s = 0.819, p < 0.001). Next, FFPE tissues (3 sections, 15 μm each per sample) from 10 patients with PCa corresponding to tumor (GS = 6 or GS ≥ 8) and adjacent benign regions were processed with the optimized protocol. Extracted proteins were analyzed by GeLC-MS/MS followed by statistical and bioinformatics analysis. Proteins significantly deregulated between PCa GS ≥ 8 and PCa GS = 6 represented extracellular matrix organization, gluconeogenesis, and phosphorylation pathways. Proteins deregulated between cancerous and adjacent benign tissues, reflected increased translation, peptide synthesis, and protein metabolism in the former, which is consistent with the literature. In conclusion, the results support the relevance of the proteomic findings in the context of PCa and the reliability of the optimized protocol for proteomics analysis of FFPE material.

pathfindR: An R Package for Comprehensive Identification of Enriched Pathways in Omics Data Through Active Subnetworks

Pathway analysis is often the first choice for studying the mechanisms underlying a phenotype. However, conventional methods for pathway analysis do not take into account complex protein-protein interaction information, resulting in incomplete conclusions. Previously, numerous approaches that utilize protein-protein interaction information to enhance pathway analysis yielded superior results compared to conventional methods. Hereby, we present pathfindR, another approach exploiting protein-protein interaction information and the first R package for active-subnetwork-oriented pathway enrichment analyses for class comparison omics experiments. Using the list of genes obtained from an omics experiment comparing two groups of samples, pathfindR identifies active subnetworks in a protein-protein interaction network. It then performs pathway enrichment analyses on these identified subnetworks. To further reduce the complexity, it provides functionality for clustering the resulting pathways. Moreover, through a scoring function, the overall activity of each pathway in each sample can be estimated. We illustrate the capabilities of our pathway analysis method on three gene expression datasets and compare our results with those obtained from three popular pathway analysis tools. The results demonstrate that literature-supported disease-related pathways ranked higher in our approach compared to the others. Moreover, pathfindR identified additional pathways relevant to the conditions that were not identified by other tools, including pathways named after the conditions.

Chinese Herbal Medicine Ganoderma tsugae Displays Potential Anti-Cancer Efficacy on Metastatic Prostate Cancer Cells

Resistance to the current therapies is the main clinical challenge in the treatment of lethal metastatic prostate cancer (mPCa). Developing novel therapeutic approaches with effective regimes and minimal side effects for this fatal disease remain a priority in prostate cancer study. In the present study, we demonstrated that a traditional Chinese medicine, quality-assured Ganoderma tsugae ethanol extract (GTEE), significantly suppressed cell growth and metastatic capability and caused cell cycle arrest through decreasing expression of cyclins in mPCa cells, PC-3 and DU145 cells. GTEE also induced caspase-dependent apoptosis in mPCa cells. We further showed the potent therapeutic efficacy of GTEE by inhibiting subcutaneous PC-3 tumor growth in a xenograft model. The in vitro and in vivo efficacies on mPCa cells were due to blockade of the PI3K/Akt and MAPK/ERK signaling pathways associated with cancer cell growth, survival and apoptosis. These preclinical data provide the molecular basis for a new potential therapeutic approach toward the treatment of lethal prostate cancer progression.

IGHG1 Regulates Prostate Cancer Growth via the MEK/ERK/c-Myc Pathway

Increasing evidence indicates that immunoglobulins are important for the regulation of various cancers including prostate cancer (PCa). However, the underlying mechanisms of IgG regulated PCa development remain to be further explored. Here, we demonstrated that IgG1 heavy chain (IGHG1) was increased in tissues from PCa patients. Inhibition of IGHG1 by antibody blocking or genetic knockdown suppressed cell growth and induced cell cycle arrest and ultimate apoptosis. Expression levels of c-Myc were positively correlated with the levels of IGHG1. Furthermore, MEK/ERK/c-Myc pathway lied downstream of IGHG1 in cultured prostate cancer cells. Inhibition of IGHG1 restrained the tumor growth in nude mice and inactivated MEK/ERK/c-Myc pathway both in vitro and in vivo. These findings suggest that IGHG1 play a crucial role during the development of prostate cancer and inhibition of IGHG1 may be a potential therapy in the treatment of PCa.

CID-6033590 inhibits p38MAPK pathway and induces S-phase cell cycle arrest and apoptosis in DU145 and PC-3 cells

Metastatic prostate cancer, with no effective treatment, is among the leading causes of cancer-associated deaths in men. Overexpression of p38αMAPK has been observed in neuroendocrine prostate cancer patients and in both DU145 and PC-3 cell lines and represents a good drug target. Sulfonamide derivatives have shown biological activities against many human diseases, including cancer. CID-6033590, a sulfonylhydrazide compound, screened from PubChem database by molecular docking with p38αMAPK, was evaluated for anti-cancerous activities. CID-6033590 induced toxicity in both DU145 and PC-3 cells in a concentration and time-dependent manner with an IC₅₀ value of 60 μM and 66 μM, respectively. Sub-cytotoxic concentrations of the compound significantly induced S-phase cell cycle arrest, inhibited cyclinA/CDK2 complex and blocked cell proliferation. Further, CID-6033590 downregulated phosphorylation of p38MAPK (P-p38) as well as its downstream targets, Activating transcription factor 2 (ATF-2) and Heat shock protein 27 (Hsp27). The compound increased ROS and decreased mitochondrial membrane potential (Δψm), downregulated Bcl-2 and survivin and cleaved poly ADP ribose polymerase (PARP) and caspase-3, indicating the induction of apoptosis. The evaluaion of the compound on noncancerous, human prostatic epithelial cell line RWPE-1, and healthy murine tissues yielded no significant toxicity. Taken together, we suggest CID-6033590 as a potential candidate for prostate cancer therapy.

Kinase impact assessment in the landscape of fusion genes that retain kinase domains: a pan-cancer study

Assessing the impact of kinase in gene fusion is essential for both identifying driver fusion genes (FGs) and developing molecular targeted therapies. Kinase domain retention is a crucial factor in kinase fusion genes (KFGs), but such a systematic investigation has not been done yet. To this end, we analyzed kinase domain retention (KDR) status in chimeric protein sequences of 914 KFGs covering 312 kinases across 13 major cancer types. Based on 171 kinase domain-retained KFGs including 101 kinases, we studied their recurrence, kinase groups, fusion partners, exon-based expression depth, short DNA motifs around the break points and networks. Our results, such as more KDR than 5'-kinase fusion genes, combinatorial effects between 3'-KDR kinases and their 5'-partners and a signal transduction-specific DNA sequence motif in the break point intronic sequences, supported positive selection on 3'-kinase fusion genes in cancer. We introduced a degree-of-frequency (DoF) score to measure the possible number of KFGs of a kinase. Interestingly, kinases with high DoF scores tended to undergo strong gene expression alteration at the break points. Furthermore, our KDR gene fusion network analysis revealed six of the seven kinases with the highest DoF scores (ALK, BRAF, MET, NTRK1, NTRK3 and RET) were all observed in thyroid carcinoma. Finally, we summarized common features of 'effective' (highly recurrent) kinases in gene fusions such as expression alteration at break point, redundant usage in multiple cancer types and 3'-location tendency. Collectively, our findings are useful for prioritizing driver kinases and FGs and provided insights into KFGs' clinical implications.

The Secret Life of Translation Initiation in Prostate Cancer

Prostate cancer (PCa) is the second most prevalent cancer in men worldwide. Despite the advances understanding the molecular processes driving the onset and progression of this disease, as well as the continued implementation of screening programs, PCa still remains a significant cause of morbidity and mortality, in particular in low-income countries. It is only recently that defects of the translation process, i.e., the synthesis of proteins by the ribosome using a messenger (m)RNA as a template, have begun to gain attention as an important cause of cancer development in different human tissues, including prostate. In particular, the initiation step of translation has been established to play a key role in tumorigenesis. In this review, we discuss the state-of-the-art of three key aspects of protein synthesis in PCa, namely, misexpression of translation initiation factors, dysregulation of the major signaling cascades regulating translation, and the therapeutic strategies based on pharmacological compounds targeting translation as a novel alternative to those based on hormones controlling the androgen receptor pathway.

Dietary Carcinogens and DNA Adducts in Prostate Cancer

Prostate cancer (PC) is the most commonly diagnosed non-cutaneous cancer and the second leading cause of cancer-related to death in men. The major risk factors for PC are age, family history, and African American ethnicity. Epidemiological studies have reported large geographical variations in PC incidence and mortality, and thus lifestyle and dietary factors influence PC risk. High fat diet, dairy products, alcohol and red meats, are considered as risk factors for PC. This book chapter provides a comprehensive, literature-based review on dietary factors and their molecular mechanisms of prostate carcinogenesis. A large portion of our knowledge is based on epidemiological studies where dietary factors such as cancer promoting agents, including high-fat, dairy products, alcohol, and cancer-initiating genotoxicants formed in cooked meats have been evaluated for PC risk. However, the precise mechanisms in the etiology of PC development remain uncertain. Additional animal and human cell-based studies are required to further our understandings of risk factors involved in PC etiology. Specific biomarkers of chemical exposures and DNA damage in the prostate can provide evidence of cancer-causing agents in the prostate. Collectively, these studies can improve public health research, nutritional education and chemoprevention strategies.

Involvement of the glutamine RF‑amide peptide and its cognate receptor GPR103 in prostate cancer

Glutamine RF‑amide peptide (QRFP) belongs to the RFamide neuropeptide family, which is involved in a wide spectrum of biological activities, ranging from food intake and cardiovascular functioning to analgesia, aldosterone secretion, locomotor activity and reproduction. Recently, QRFP has been demonstrated to exert its effects by activating the G protein‑coupled receptor GPR103. QRFP is expressed in the brain and peripherally in the adipose tissue, bladder, colon, testis, parathyroid and thyroid gland, as well as in the prostate gland. Following lung cancer, prostate cancer constitutes the second most frequently diagnosed cancer among men, whilst obesity appears to be a contributing factor for aggressive prostate cancer. In the present study, we sought to investigate the role of QRFP in prostate cancer, using two androgen‑independent human prostate cancer cell lines (PC3 and DU145) as in vitro experimental models and clinical human prostate cancer samples. The expression of both QRFP and GPR103 at the gene and protein level was higher in human prostate cancer tissue samples compared to control and benign prostatic hyperplasia (BHP) samples. Furthermore, in both prostate cancer cell lines used in the present study, QRFP treatment induced the phosphorylation of ERK1/2, p38, JNK and Akt. In addition, QRFP increased cell migration and invasion in these in vitro models, with the increased expression of MMP2. Furthermore, we demonstrated that the pleiotropic adipokine, leptin, increased the expression of QRFP and GPR103 in PC3 prostate cancer cells via a PI3K‑ and MAPK‑dependent mechanism, indicating a novel potential link between adiposity and prostate cancer. Our findings expand the existing evidence and provide novel insight into the implication of QRFP in prostate cancer.

Dual functions for OVAAL in initiation of RAF/MEK/ERK prosurvival signals and evasion of p27-mediated cellular senescence

Here, we report that the long noncoding RNA (lncRNA) ovarian adenocarcinoma-amplified lncRNA (OVAAL) is a mediator of cancer cell resistance, counteracting the effects of apoptosis-inducing agents acting through both the extrinsic and intrinsic pathways. Building upon previous reports associating OVAAL amplification with ovarian and endometrial cancers, we now show that OVAAL overexpression occurs during the pathogenesis of colorectal cancer and melanoma. Mechanistically, our findings also establish that OVAAL expression more generally contributes a prosurvival role to cancer cells under steady-state conditions. OVAAL accomplishes these actions utilizing distinct functional modalities: one promoting activation of RAF/MEK/ERK signaling and the other blocking cell entry into senescence. Our study demonstrates that expression of a single OVAAL in cancer cells drives two distinct but coordinated actions contributing to cancer pathology.

Long noncoding RNAs (lncRNAs) function through a diverse array of mechanisms that are not presently fully understood. Here, we sought to find lncRNAs differentially regulated in cancer cells resistant to either TNF-related apoptosis-inducing ligand (TRAIL) or the Mcl-1 inhibitor UMI-77, agents that act through the extrinsic and intrinsic apoptotic pathways, respectively. This work identified a commonly up-regulated lncRNA, ovarian adenocarcinoma-amplified lncRNA (OVAAL), that conferred apoptotic resistance in multiple cancer types. Analysis of clinical samples revealed OVAAL expression was significantly increased in colorectal cancers and melanoma in comparison to the corresponding normal tissues. Functional investigations showed that OVAAL depletion significantly inhibited cancer cell proliferation and retarded tumor xenograft growth. Mechanically, OVAAL physically interacted with serine/threonine-protein kinase 3 (STK3), which, in turn, enhanced the binding between STK3 and Raf-1. The ternary complex OVAAL/STK3/Raf-1 enhanced the activation of the RAF protooncogene serine/threonine-protein kinase (RAF)/mitogen-activated protein kinase kinase 1 (MEK)/ERK signaling cascade, thus promoting c-Myc–mediated cell proliferation and Mcl-1–mediated cell survival. On the other hand, depletion of OVAAL triggered cellular senescence through polypyrimidine tract-binding protein 1 (PTBP1)–mediated p27 expression, which was regulated by competitive binding between OVAAL and p27 mRNA to PTBP1. Additionally, c-Myc was demonstrated to drive OVAAL transcription, indicating a positive feedback loop between c-Myc and OVAAL in controlling tumor growth. Taken together, these results reveal that OVAAL contributes to the survival of cancer cells through dual mechanisms controlling RAF/MEK/ERK signaling and p27-mediated cell senescence.

Anoikis‑resistant human osteosarcoma cells display significant angiogenesis by activating the Src kinase‑mediated MAPK pathway

Tumor cells must resist anoikis to metastasize. There is a key role of angiogenesis in the growth and metastasis of tumors. However, the relationship between anoikis resistance and angiogenesis has not been well explored in human osteosarcoma. In the present study, we reported the higher expression of vascular endothelial growth factor-A (VEGF-A) in osteosarcoma cells that were resistant to anoikis than in parental osteosarcoma cells, promoting the proliferation, tube formation, and migration of human umbilical vein endothelial cells (HUVECs). Src, JNK (Jun amino-terminal kinase) and ERK (extracellular signal-regulated kinase) signaling pathway phosphorylation was activated in anoikis-resistant cells; Src inhibitor reduced the expression of VEGF-A and angiogenesis and inhibited JNK and ERK pathway activity. Overexpression of phosphorylated (p)-Src and VEGF-A was positively correlated to the metastatic potential in human osteosarcoma tissues, as quantified by immunohistochemistry. In addition, p-Src expression was directly correlated with VEGF-A expression and microvessel density in vivo. Our findings revealed that anoikis resistance in osteosarcoma cells increased the expression of VEGF-A and angiogenesis through the Src/JNK/ERK signaling pathways. Thus, Src may be a potential therapeutic alternative in osteosarcoma angiogenesis and metastasis.

Pharmacological inhibition of the Notch pathway enhances the efficacy of androgen deprivation therapy for prostate cancer

Although androgen deprivation therapy (ADT) is a standard treatment for metastatic prostate cancer, this disease inevitably recurs and progresses to ADT-resistant stage after this therapy. Accordingly, understanding the mechanism of resistance to ADT and finding new approach to enhance the efficacy of ADT may provide a major benefit to PCa patients. In our study, we found upregulated expression of Notch receptors is positive associated with ADT-resistance progression. Using fluorescent Notch signaling reporter system, we observed that endogenous Notch signaling could be activated after treatment of androgen deprivation in LNCaP cells via activation of Notch3. In addition, exogenous activation of the Notch signaling though Dox-induced overexpression of any Notch intracellular domains (NICD1-4) could enhance the resistance of PCa cells to ADT under ex vivo 3D culture conditions and upregulate expression of ADT resistance-associated phospho-p38 and Bcl-2 in LNCaP cells. As a result, pharmacological inhibition of the Notch pathway using γ-secretase inhibitor (GSI), DAPT, downregulated both phospho-p38 and Bcl-2 expression and significantly enhanced the efficacy of ADT in androgen sensitive PCa cells with impaired proliferation and 3D colony formation, increased apoptosis and remarkable inhibition of tumor growth in murine subcutaneous xenograft model. These results indicate that activated Notch signaling contributes to ADT resistance, and suggest that inhibition of the Notch pathway may be a promising adjuvant therapy of ADT for PCa.

Protective Effect of Sulfated Polysaccharides from Celluclast-Assisted Extract of Hizikia fusiforme Against Ultraviolet B-Induced Skin Damage by Regulating NF-κB, AP-1, and MAPKs Signaling Pathways In Vitro in Human Dermal Fibroblasts

Our previous study evaluated the antioxidant activities of sulfated polysaccharides from Celluclast-assisted extract of Hizikia fusiforme (HFPS) in vitro in Vero cells and in vivo in zebrafish. The results showed that HFPS possesses strong antioxidant activity and suggested the potential photo-protective activities of HFPS. Hence, in the present study, we investigated the protective effects of HFPS against ultraviolet (UV) B-induced skin damage in vitro in human dermal fibroblasts (HDF cells). The results indicate that HFPS significantly reduced intracellular reactive oxygen species (ROS) level and improved the viability of UVB-irradiated HDF cells in a dose-dependent manner. Furthermore, HFPS significantly inhibited intracellular collagenase and elastase activities, remarkably protected collagen synthesis, and reduced matrix metalloproteinases (MMPs) expression by regulating nuclear factor kappa B (NF-κB), activator protein 1 (AP-1), and mitogen-activated protein kinases (MAPKs) signaling pathways in UVB-irradiated HDF cells. These results suggest that HFPS possesses strong UV protective effect, and can be a potential ingredient in the pharmaceutical and cosmetic industries.

Disruption of MEK/ERK/c-Myc signaling radiosensitizes prostate cancer cells in vitro and in vivo

PURPOSE

Prostate cancer (PCa) cell radioresistance causes the failure of radiation therapy (RT) in localized or locally advanced disease. The aberrant accumulation of c-Myc oncoprotein, known to promote PCa onset and progression, may be due to the control of gene transcription and/or MEK/ERK-regulated protein stabilization. Here, we investigated the role of MEK/ERK signaling in PCa.

METHODS

LnCAP, 22Rv1, DU145, and PC3 PCa cell lines were used in in vitro and in vivo experiments. U0126, trametinib MEK/ERK inhibitors, and c-Myc shRNAs were used. Radiation was delivered using an x-6 MV photon linear accelerator. U0126 in vivo activity alone or in combination with irradiation was determined in murine xenografts.

RESULTS

Inhibition of MEK/ERK signaling down-regulated c-Myc protein in PCa cell lines to varying extents by affecting expression of RNA and protein, which in turn determined radiosensitization in in vitro and in vivo xenograft models of PCa cells. The crucial role played by c-Myc in the MEK/ERK pathways was demonstrated in 22Rv1 cells by the silencing of c-Myc by means of short hairpin mRNA, which yielded effects resembling the targeting of MEK/ERK signaling. The clinically approved compound trametinib used in vitro yielded the same effects as U0126 on growth and C-Myc expression. Notably, U0126 and trametinib induced a drastic down-regulation of BMX, which is known to prevent apoptosis in cancer cells.

CONCLUSIONS

The results of our study suggest that signal transduction-based therapy can, by disrupting the MEK/ERK/c-Myc axis, reduce human PCa radioresistance caused by increased c-Myc expression in vivo and in vitro and restores apoptosis signals.

Drug-like dietary vanilloids induce anticancer activity through proliferation inhibition and regulation of bcl-related apoptotic proteins

In this study, a series of 20 structurally similar vanilloids (Vn) were tested for their antiproliferative effects against 12 human cancer cells: human breast (MCF-7 and MDA-MB-231), cervical (HeLa), ovarian (Caov-3), lung (A549), liver (HepG2), colorectal (HT-29 and HCT116), nasopharyngeal (CNE-1 and HK-1), and leukemic (K562 and CEM-SS) cancer cells. Among all the tested vanilloids, Vn16 (6-shogaol) exhibited the most potent cytotoxic effects against human colorectal cancer cells (HT-29). The apoptotic induction effects exhibited by Vn16 on HT-29 cells were confirmed using dual staining fluorescence microscopy and enzyme-linked immunosorbent assay. The effects of Vn16 on regulation of 43 apoptotic-related markers were determined in HT-29. The results suggested that 8 apoptotic markers (caspase 8, BAD, BAX, second mitochondrial-derived activator, caspase 3, survivin, bcl-2, and cIAP-2) were either upregulated or downregulated. These results further support the chemopreventive properties of foods that contain vanilloids.

Selective Androgen Receptor Modulator S42 Suppresses Prostate Cancer Cell Proliferation

We previously identified the selective androgen receptor (AR) modulator S42, which does not stimulate prostate growth but has a beneficial effect on lipid metabolism. In the prostate cancer (PC) cell line LNCaP, S42 did not induce AR transactivation but antagonized 5α-dihydrotestosterone (DHT)‒induced AR activation. Next, we investigated whether S42 suppresses the growth of PC cell lines. Basal growth of LNCaP cells was significantly suppressed by treatment with S42 compared with vehicle, as determined by cell counting and 5-bromo-2'-deoxyuridine assays. The suppressive effect of S42 on cell growth was evident in the AR-positive PC cells LNCaP and 22Rv1 and was slightly observed even in the AR-negative PC-3 cells. However, S42 did not induce apoptosis as determined by the terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling assay. S42 had an even greater suppressive effect on DHT-dependent LNCaP cell proliferation than on basal proliferation (P < 0.05). DHT treatment increased the expression of phosphorylated extracellular signal-regulated kinase (ERK)-mitogen-activated protein kinase (MAPK), a major signaling molecule for PC proliferation, and this was significantly inhibited by S42. DHT also significantly upregulated AR, insulinlike growth factor-1 receptor (IGF-1R), and insulin receptor (IR)-β protein levels, which were similarly reduced by S42 treatment. Importantly, S42 administration to mice attenuated the growth of LNCaP tumors and reduced tumor expression of the prostate-specific antigen, P504S, Ki67, and phosphorylated ERK-MAPK. These data suggest that S42 attenuates LNCaP tumor growth not by inducing apoptosis but by inhibiting the expression of proliferation-related receptors, including IGF-1R, IR, and AR, and by suppressing ERK-MAPK activation. S42 may thus be a feasible candidate for PC treatment.

Prunella vulgaris L. Exerts a Protective Effect Against Extrinsic Aging Through NF-κB, MAPKs, AP-1, and TGF-β/Smad Signaling Pathways in UVB-Aged Normal Human Dermal Fibroblasts

Prunella vulgaris L., a well-known traditional Chinese herbal medicine, has anti-inflammatory and antioxidant activities. In the present study, the underlying molecular mechanisms of the protective effect of P. vulgaris extract (PVE) were investigated in UVB-irradiated normal human dermal fibroblasts (NHDFs). The mRNA expression of matrix metalloproteinases (MMPs), procollagen type I, and cytokines, such as interleukin-6 (IL-6) and tumor necrosis factor (TNF-α), was determined by reverse transcription–polymerase chain reaction. The expression of anti-photoaging-related signaling molecules in the NF-κB, MAPK/AP-1, and TGF/Smad pathways was assessed by western blot. We observed that PVE blocked the upregulated production of radical oxygen species induced in UVB-irradiated NHDFs in a dose-dependent manner. Treatment with PVE also significantly ameliorated the mRNA levels of MMPs, procollagen type I, TNF-α, and IL-6. In addition, the phosphorylation level of c-Jun and c-Fos was decreased through the attenuated expression levels of p-ERK and p-JNK after treatment with PVE. Furthermore, cells treated with PVE showed inhibited Smad 7 and increased Smad 2/3 expression in the TGF-β/Smad signaling pathway. Hence, synthesis of procollagen type I, a precursor of collagen I, was promoted. These findings indicate that treatment with PVE has a potential protective effect against UVB-induced photoaging and photoinflammation.