LNCaP Atlas: gene expression associated with in vivo progression to castration-recurrent prostate cancer

Role of hematological and neurological expressed 1 (HN1) in human cancers

Hematological and neurological expressed 1 (HN1), also known as Jupiter microtubule associated homolog 1 (JPT1), is a highly conserved protein with widespread expression in various tissues. Ectopic elevation of HN1 has been observed in multiple cancers, highlighting its role in tumorigenesis and progression. Both proteomics and transcriptomics reveal that HN1 is closely associated with severe disease progression, poor prognostic and shorter overall survival. HN1's involvement in cancer cell proliferation and metastasis has been extensively investigated. Overexpression of HN1 is associated with increased tumor growth and disease progression, while its depletion leads to cell cycle arrest and apoptosis. The pivotal role of HN1 in cancer progression, particularly in proliferation, migration, and invasion, underscores its significance in cancer metastasis. Validation of the efficacy and safety of HN1 inhibition, along with the development of diagnostic methods to determine HN1 expression levels in patients, is essential for the translation of HN1-targeted therapies into clinical practice. Overall, HN1 emerges as a valuable prognostic marker and therapeutic target in cancer, and further investigations hold the potential to improve patient outcomes by impeding metastasis and enhancing treatment strategies.

Regulation of Molecular Biomarkers Associated with the Progression of Prostate Cancer

Androgen receptor signaling regulates the normal and pathological growth of the prostate. In particular, the growth and survival of prostate cancer cells is initially dependent on androgen receptor signaling. Exposure to androgen deprivation therapy leads to the development of castration-resistant prostate cancer. There is a multitude of molecular and cellular changes that occur in prostate tumor cells, including the expression of neuroendocrine features and various biomarkers, which promotes the switch of cancer cells to androgen-independent growth. These biomarkers include transcription factors (TP53, REST, BRN2, INSM1, c-Myc), signaling molecules (PTEN, Aurora kinases, retinoblastoma tumor suppressor, calcium-binding proteins), and receptors (glucocorticoid, androgen receptor-variant 7), among others. It is believed that genetic modifications, therapeutic treatments, and changes in the tumor microenvironment are contributing factors to the progression of prostate cancers with significant heterogeneity in their phenotypic characteristics. However, it is not well understood how these phenotypic characteristics and molecular modifications arise under specific treatment conditions. In this work, we summarize some of the most important molecular changes associated with the progression of prostate cancers and we describe some of the factors involved in these cellular processes.

Pan-caner analysis identifies PSMA7 as a targets for amplification at 20q13.33 in tumorigenesis

The chromosome 20 long arm (20q) is one of the genomic hotspots where copy number alterations frequently occur in multiple types of tumors. However, it remains elusive which genes are implicated in 20q-related tumorigenesis. Here, by querying TCGA and GEO databases, we observed frequent copy number amplification at 20q and the chromosome subband 20q13.33 was amplificated in multiple cancers. Among those genes at 20q13.33, PSMA7 was found with the strongest correlation with cancers. Further analysis revealed that PSMA7 amplification was the most frequent genetic alteration event conferring adverse prognosis in various cancers. Consistent with the strong positive correlation between PSMA7 amplification and gene expression, elevated PSMA7 expression was observed in 20 of 33 types of cancers with a close link to adverse outcomes in certain tumors. In addition, PSMA7 was essential for the growth of almost 1095 cancer lines. Mechanistically, aberrant PSMA7 most probably influenced the proteasome and protease-related pathways to promote tumorigenesis and might be antagonized by several compounds, e.g., Docetaxel in relevant cancers. The current in-depth pan-cancer analysis refines our understanding of the crucial oncogenic role of copy number amplifications at PSMA7 loci at the novel chromosome amplicon 20q13.33 across different tumors.

DHCR24 in Tumor Diagnosis and Treatment: A Comprehensive Review

As an important nutrient in the human body, cholesterol can not only provide structural components for the body's cells, but also can be transformed into a variety of active substances to regulate cell signaling pathways. As an important cholesterol synthase, DHCR24 participates in important regulatory processes in the body. The application of DHCR24 in tumor clinical diagnosis and treatment also attracts much attention. This article reviews the structure and regulatory characteristics of DHCR24, and the research of DHCR24 on tumor progression. We summarize the possible mechanisms of DHCR24 promoting tumor progression through reactive oxygen species (ROS), p53, Ras and PI3K-AKT pathways. Through our review, we hope to provide more research ideas and reference value for the application of DHCR24 in tumor prevention and treatment.

Reduction in Nuclear Size by DHRS7 in Prostate Cancer Cells and by Estradiol Propionate in DHRS7-Depleted Cells

Increased nuclear size correlates with lower survival rates and higher grades for prostate cancer. The short-chain dehydrogenase/reductase (SDR) family member DHRS7 was suggested as a biomarker for use in prostate cancer grading because it is largely lost in higher-grade tumors. Here, we found that reduction in DHRS7 from the LNCaP prostate cancer cell line with normally high levels of DHRS7 increases nuclear size, potentially explaining the nuclear size increase observed in higher-grade prostate tumors where it is lost. An exogenous expression of DHRS7 in the PC3 prostate cancer cell line with normally low DHRS7 levels correspondingly decreases nuclear size. We separately tested 80 compounds from the Microsource Spectrum library for their ability to restore normal smaller nuclear size to PC3 cells, finding that estradiol propionate had the same effect as the re-expression of DHRS7 in PC3 cells. However, the drug had no effect on LNCaP cells or PC3 cells re-expressing DHRS7. We speculate that separately reported beneficial effects of estrogens in androgen-independent prostate cancer may only occur with the loss of DHRS7/ increased nuclear size, and thus propose DHRS7 levels and nuclear size as potential biomarkers for the likely effectiveness of estrogen-based treatments.

Aberrant expression of multiple glycolytic enzyme genes is significantly associated with disease progression and survival outcomes in prostate cancers

Prostate cancer is the leading cause of cancer death after lung cancer in men. Recent studies showed that aberrant metabolic pathways are involved in prostate cancer development and progression. In this study, we performed a systemic analysis of glycolytic enzyme gene expression using the TCGA-PRAD RNAseq dataset. Our analysis revealed that among 25 genes, only four genes (HK2/GPI/PFKL/PGAM5) were significantly upregulated while nine genes (HK1/GCK/PFKM/PFKP/ALDOC/PGK1/PGAM1/ENO2/PKM) were downregulated in primary prostate cancer tissues compared to benign compartments. Among these 13 altered genes, four genes (ENO2/ALDOC/GPI/GCK) exhibited strong diagnostic potential in distinguishing malignant and benign tissues. Meanwhile, GPI expression exerted as a prognostic factor of progression-free and disease-specific survival. PFKL and PGAM5 gene expressions were associated with AR signaling scores in castration-resistant patients, and AR-targeted therapy suppressed their expression. In LuCap35 xenograft tumors, PFKL and PGAM5 expression was significantly reduced after animal castration, confirming the AR dependency. Conversely, GCK/PKLR genes were significantly associated with neuroendocrinal progression, representing two novel neuroendocrinal biomarkers for prostate cancer. In conclusion, our results suggest that GPI expression is a strong prognostic factor for prostate cancer progression and survival while GCK/PKLR are two novel biomarkers of prostate cancer progression to neuroendocrinal status.

Characterization of the TRPV6 calcium channel-specific phenotype by RNA-seq in castration-resistant human prostate cancer cells

Background: Transient receptor potential vanilloid subfamily member 6 (TRPV6), a highly calcium-selective channel, has been shown to play a significant role in calcium homeostasis and to participate both in vitro and in vivo in growth, cell survival, and drug resistance of prostate cancer. Its role and the corresponding calcium-dependent pathways were mainly studied in hormone-dependent human prostate cancer cell lines, often used as a model of early-stage prostate cancers. The goal of the present study was to describe the TRPV6-specific phenotype and signaling pathways it is involved in, using castration-resistant prostate cancer cell lines. Methods: RNA sequencing (RNA-seq) was used to study the gene expression impacted by TRPV6 using PC3Mtrpv6-/- versus PC3Mtrpv6+/+ and its derivative PC3M-luc-C6trpv6+/+ cell line in its native and TRPV6 overexpressed form. In addition to the whole-cell RNA sequencing, immunoblotting, quantitative PCR, and calcium imaging were used to validate trpv6 gene status and functional consequences, in both trpv6 -/- and TRPV6 overexpression cell lines. Results: trpv6 -/- status was validated using both immunoblotting and quantitative PCR, and the functional consequences of either trpv6 gene deletion or TRPV6 overexpression were shown using calcium imaging. RNA-seq analysis demonstrated that the calcium channel TRPV6, being a crucial player of calcium signaling, significantly impacts the expression of genes involved in cancer progression, such as cell cycle regulation, chemotaxis, migration, invasion, apoptosis, ferroptosis as well as drug resistance, and extracellular matrix (ECM) re-organization. Conclusion: Our data suggest that the trpv6 gene is involved in and regulates multiple pathways related to tumor progression and drug resistance in castration-resistant prostate cancer cells.

The immunoexpression of valosin-containing protein and small VCP-interacting protein in rat ovaries

Numerous cellular processes are controlled by the ubiquitin-proteasome-mediated degradation pathway, involve the 97-kDa valosin-containing protein (p97/VCP). Small p97/VCP-interacting protein (SVIP) was first discovered as one of the novel androgen-responsive genes as well as one of the many cofactors controlling p97/VCP. The aim of the study was to investigate localization and immunoexpression of p97/VCP and SVIP in rat ovarian tissue. The histomorphological examination of rat ovarian tissue was performed by using haematoxylin-eosin (HE) staining. Using the immunohistochemical technique, cellular location and expression of p97/VCP and SVIP in rat ovarian tissue were examined. The nuclear and cytoplasmic immunoexpression of p97/VCP and SVIP was observed in the different stages of ovarian follicles and corpus luteum in the rat ovaries. The immunolocalization of SVIP and VCP in the rat ovaries suggest that they may be involved in the oogenesis. Further studies should be performed about the function of the VCP and SVIP in the female reproductive tract.

HN1 Is Enriched in the S-Phase, Phosphorylated in Mitosis, and Contributes to Cyclin B1 Degradation in Prostate Cancer Cells

HN1 has previously been shown as overexpressed in various cancers. In Prostate cancer, it regulates AR signaling and centrosome-related functions. Previously, in two different studies, HN1 expression has been observed as inversely correlated with Cyclin B1. However, HN1 interacting partners and the role of HN1 interactions in cell cycle pathways have not been completely elucidated. Therefore, we used Prostate cancer cell lines again and utilized both transient and stable inducible overexpression systems to delineate the role of HN1 in the cell cycle. HN1 characterization was performed using treatments of kinase inhibitors, western blotting, flow cytometry, immunofluorescence, cellular fractionation, and immunoprecipitation approaches. Our findings suggest that HN1 overexpression before mitosis (post-G2), using both transient and stable expression systems, leads to S-phase accumulation and causes early mitotic exit after post-G2 overexpression. Mechanistically, HN1 interacted with Cyclin B1 and increased its degradation via ubiquitination through stabilized Cdh1, which is a co-factor of the APC/C complex. Stably HN1-expressing cells exhibited a reduced Cdt1 loading onto chromatin, demonstrating an exit from a G1 to S phenotype. We found HN1 and Cdh1 interaction as a new regulator of the Cyclin B1/CDK1 axis in mitotic regulation which can be explored further to dissect the roles of HN1 in the cell cycle.

Physiological and Pathological Functions of TMEM30A: An Essential Subunit of P4-ATPase Phospholipid Flippases

Phospholipids are asymmetrically distributed across mammalian plasma membrane. The function of P4-ATPases is to maintain the abundance of phosphatidylserine (PS) and phosphatidylethanolamine (PE) in the inner leaflet as lipid flippases. Transmembrane protein 30A (TMEM30A, also named CDC50A), as an essential β subunit of most P4-ATPases, facilitates their transport and functions. With TMEM30A knockout mice or cell lines, it is found that the loss of TMEM30A has huge influences on the survival of mice and cells because of PS exposure-triggered apoptosis signaling. TMEM30A is a promising target for drug discovery due to its significant roles in various systems and diseases. In this review, we summarize the functions of TMEM30A in different systems, present current understanding of the protein structures and mechanisms of TMEM30A-P4-ATPase complexes, and discuss how these fundamental aspects of TMEM30A may be applied to disease treatment.

IL-6 evoked biochemical changes in prostate cancer cells

The pro-inflammatory cytokine IL-6 has been associated with the progression of PCa to a castration-resistant phenotype. In this work, we characterized the biochemical changes evoked by IL-6 in three different models of PCa cells, including LNCaP, C4-2, and PC3. The effect of IL-6 on PCa cells was compared with the effect obtained by co-stimulation with the cAMP-inducing agent forskolin (FSK). Stimulation of LNCaP cells with IL-6 or IL-6 + FSK evoked increased expression of the neuroendocrine marker tubulin IIIβ and Cav3.2 T-type Ca²⁺ channel subunit. PC3 cells, representing a more advanced state of PCa, had high levels of tubulin IIIβ expression without any further changes observed by treatment with IL-6 or IL-6 + FSK. Elevated expression of the glucocorticoid receptor was observed in PC3, but not in LNCaP or C4-2 cells. Glucocorticoid receptor expression was not regulated by IL-6 stimulation of LNCaP or C4-2 cells. IL-6 acting alone or together with FSK evoked a significant reduction in the expression of the transcription factor REST and retinoblastoma tumor suppressor protein Rb1. In LNCaP cells, IL-6 acting alone or together with FSK had no effect on the expression of several biological markers of advanced PCa, including Aurora kinase A, valosin-containing protein, calcium-sensing receptor, calreticulin, S100A protein, and Protein S. In PC3 cells, co-treatment with IL-6 + FSK evoked increased expression of REST and S100A proteins, as well as a reduction in Protein S levels. These findings reveal a complex pattern of biochemical changes in PCa cells under the influence of IL-6.

Monoamine oxidase A: An emerging therapeutic target in prostate cancer

Monoamine oxidase A (MAOA), a mitochondrial enzyme degrading biogenic and dietary amines, has been studied in the contexts of neuropsychiatry and neurological disorders for decades, but its importance in oncology, as best exemplified in prostate cancer (PC) to date, was only realized recently. PC is the most commonly diagnosed non-skin cancer and the second deadliest malignancy for men in the United States. In PC, the increased expression level of MAOA is correlated with dedifferentiated tissue microarchitecture and a worse prognosis. A wealth of literature has demonstrated that MAOA promotes growth, metastasis, stemness and therapy resistance in PC, mainly by increasing oxidative stress, augmenting hypoxia, inducing epithelial-to-mesenchymal transition, and activating the downstream principal transcription factor Twist1-dictated multiple context-dependent signaling cascades. Cancer-cell-derived MAOA also enables cancer-stromal cell interaction involving bone stromal cells and nerve cells by secretion of Hedgehog and class 3 semaphorin molecules respectively to modulate the tumor microenvironment in favor of invasion and metastasis. Further, MAOA in prostate stromal cells promotes PC tumorigenesis and stemness. Current studies suggest that MAOA functions in PC in both cell autonomous and non-autonomous manners. Importantly, clinically available monoamine oxidase inhibitors have shown promising results against PC in preclinical models and clinical trials, providing a great opportunity to repurpose them as a PC therapy. Here, we summarize recent advances in our understanding of MAOA roles and mechanisms in PC, present several MAOA-targeted strategies that have been nominated for treating PC, and discuss the unknowns of MAOA function and targeting in PC for future exploration.

Loading of "cocktail siRNAs" into extracellular vesicles via TAT-DRBD peptide for the treatment of castration-resistant prostate cancer

Extracellular vesicles (EVs) are cell-derived, membranous nanoparticles that mediate intercellular communication by transferring biomolecules between cells. As natural vehicles, EVs may exhibit higher delivery efficiency, lower immunogenicity, and better compatibility than existing RNA carriers. A major limitation of their therapeutic use is the shortage of efficient, robust, and scalable methods to load siRNA of interest. Here, we report a novel strategy using polycationic membrane-penetrating peptide TAT to encapsulate siRNAs into EVs. Three TAT peptides were co-expressed with DRBD as 3TD fusion protein. The sequence-independent binding of DRBD facilitates multiplex genes targeting of mixed siRNAs. Functional assays for siRNA-mediated gene silencing of CRPC were performed after engineered EVs treatment. EVs were isolated using differential centrifugation from WPMY-1 cell culture medium. The increase of merged yellow fluorescence in the engineered EVs showed by TIRFM and the decrease in zeta potential absolute values certified the co-localization of siRNA with EVs, which indicated that siRNA had been successfully delivered into WPMY-1 EVs. qRT-PCR analysis revealed that the mRNA level of FLOH1, NKX3, and DHRS7 was dramatically decreased when cells were treated with engineered EVs loaded with siRNAs mixtures relative to the level of untreated cells. Western and flow cytometry results indicate that delivery of siRNA mixtures by engineered EVs can effectively downregulate AR expression and induce LNCaP-AI cell apoptosis. The uptake efficiency of the EVs and the significantly downregulated expression of three genes suggested the potential of TAT as efficient siRNA carriers by keeping the function of the cargoes.

Crosstalk between lncRNAs in the apoptotic pathway and therapeutic targets in cancer

The assertion that a significant portion of the mammalian genome has not been translated and that non-coding RNA accounts for over half of polyadenylate RNA have received much attention. In recent years, increasing evidence proposes non-coding RNAs (ncRNAs) as new regulators of various cellular processes, including cancer progression and nerve damage. Apoptosis is a type of programmed cell death critical for homeostasis and tissue development. Cancer cells often have inhibited apoptotic pathways. It has recently been demonstrated that up/down-regulation of various lncRNAs in certain types of tumors shapes cancer cells' response to apoptotic stimuli. This review discusses the most recent studies on lncRNAs and apoptosis in healthy and cancer cells. In addition, the role of lncRNAs as novel targets for cancer therapy is reviewed here. Finally, since it has been shown that lncRNA expression is associated with specific types of cancer, the potential for using lncRNAs as biomarkers is also discussed.

Role of MicroRNAs in Neuroendocrine Prostate Cancer

Therapy-induced neuroendocrine prostate cancer (t-NEPC/NEPC) is an aggressive variant of prostate cancer (PCa) that frequently emerges in castration-resistant prostate cancer (CRPC) under the selective pressure of androgen receptor (AR)-targeted therapies. This variant is extremely aggressive, metastasizes to visceral organs, tissues, and bones despite low serum PSA, and is associated with poor survival rates. It arises via a reversible trans-differentiation process, referred to as ‘neuroendocrine differentiation’ (NED), wherein PCa cells undergo a lineage switch and exhibit neuroendocrine features, characterized by the expression of neuronal markers such as enolase 2 (ENO2), chromogranin A (CHGA), and synaptophysin (SYP). The molecular and cellular mechanisms underlying NED in PCa are complex and not clearly understood, which contributes to a lack of effective molecular biomarkers for diagnosis and therapy of this variant. NEPC is thought to derive from prostate adenocarcinomas by clonal evolution. A characteristic set of genetic alterations, such as dual loss of retinoblastoma (RB1) and tumor protein (TP53) tumor suppressor genes and amplifications of Aurora kinase A (AURKA), NMYC, and EZH2, has been reported to drive NEPC. Recent evidence suggests that microRNAs (miRNAs) are important epigenetic players in driving NED in advanced PCa. In this review, we highlight the role of miRNAs in NEPC. These studies emphasize the diverse role that miRNAs play as oncogenes and tumor suppressors in driving NEPC. These studies have unveiled the important role of cellular processes such as the EMT and cancer stemness in determining NED in PCa. Furthermore, miRNAs are involved in intercellular communication between tumor cells and stromal cells via extracellular vesicles/exosomes that contribute to lineage switching. Recent studies support the promising potential of miRNAs as novel diagnostic biomarkers and therapeutic targets for NEPC.

PCGEM1 promotes proliferation, migration and invasion in prostate cancer by sponging miR-506 to upregulate TRIAP1

BACKGROUND

The important role of long noncoding RNAs (lncRNAs) in cancer has been demonstrated in many studies. Prostate cancer gene expression marker 1 (PCGEM1) is a lncRNA specifically expressed within the prostate and overexpressed in many cancer cells. Numerous studies have shown that PCGEM1 promotes cell proliferation, invasion and migration. However, the specific mechanism of PCGEM1 within prostate cancer (PCa) has not been elucidated. MicroRNA-506-3p (miR-506-3p) is a noncoding RNA, and studies have indicated that miR-506-3p is downregulated in prostate cancer cell lines and functions as a tumor suppressor.

METHODS

The TCGA (GEPIA) database ( http://gepia.cancer-pku.cn/ ) was employed to measure PCGEM1 levels in PCa. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to determine the PCGEM1 gene level. CCK-8 (Cell Counting Kit-8) and colony formation assays were used to detect cell proliferation, and Transwell assays were applied to assess cell invasion and migration. The interacting ability of miR-506-3p with PCGEM1 or TRIAP1 was validated through a dual-luciferase reporter assay. TRIAP1 protein expression was detected by Western blotting.

RESULTS

PCGEM1 expression was increased in PCa tissues and cells. In PCa tissues, High PCGEM1 expression was associated with high Gleason score, distant metastasis and extracapsular extension. In addition, PCGEM1 knockdown inhibited PCa cell (C4-2B and PC-3) proliferation, invasion and migration. miR-506-3p may interact with PCGEM1 or TRIAP1, and the suppressive effect of PCGEM1 knockdown was reversed when TRIAP1 or a miR-506-3p inhibitor was cotransfected.

CONCLUSION

PCGEM1 expression increased in PCa cells and tissues, enhancing PCa cell proliferation, migration and invasion by sponging miR-506 to upregulate TRIAP1.

Growth arrest-specific 5 lncRNA as a valuable biomarker of chemoresistance in osteosarcoma

Osteosarcoma is the most common primary malignant bone tumour in children and teenagers, and it is characterised by drug resistance and high metastatic potential. Increasing studies have highlighted the critical roles of long noncoding RNAs (lncRNAs) as oncogenes or tumour suppressors as well as new biomarkers and therapeutic targets in osteosarcoma. The growth arrestspecific 5 (GAS5) lncRNA can function as a tumour suppressor in several cancers. The present study aimed to validate GAS5 and other chemoresistanceassociated lncRNAs as biomarkers in a cohort of primary osteosarcoma samples, to obtain predictive information on resistance or sensitivity to treatment. The GAS5 and a panel of lncRNAs related to chemoresistance [SNGH1, FOXD2-AS1, deleted in lymphocytic leukemia (DLEU2) and LINC00963] were evaluated in a cohort of osteosarcoma patients enrolled at the Careggi University Hospital. Total RNA was extracted from formalin-fixed paraffin-embedded (FFPE) tissue sections and the expression levels of the lncRNAs were quantified by qPCR. A bioinformatic analysis on deposited RNA-seq data was performed to validate the qPCR results. Clustering analysis shows that GAS5 could be linked to the expression of isoforms 02 and 04 of the lncRNA DLEU2, whereas the DLEU2 isoform 08 is linked to the lncRNA LINC00963. We found that GAS5 is significantly increased in patients with a good prognosis and is expressed differently between chemosensitive and chemoresistant osteosarcoma patients. However, the results obtained are not concordant with the in-silico analysis performed on the TARGET osteosarcoma dataset. In the future, we would enlarge the case series, including different disease settings.

Vitamin K2 Inhibits Hepatocellular Carcinoma Cell Proliferation by Binding to 17β-Hydroxysteroid Dehydrogenase 4

Our previous studies have proved that 17β-hydroxysteroid dehydrogenase 4 (HSD17B4) is a novel proliferation-promoting protein. The overexpression of HSD17B4 promotes hepatocellular carcinoma (HCC) cell proliferation. Vitamin K2 (VK2), a fat-soluble vitamin, has the function of promoting coagulation and can inhibit the progression of liver cancer. A previous study demonstrated that VK2 could bind to HSD17B4 in HepG2 cells. However, the mechanism of VK2 in inhibiting HCC cell proliferation is not clear. In this study, we investigate whether VK2 can inhibit the proliferation of HCC cell induced by HSD17B4 and the possible mechanism. We detected the effect of VK2 on HSD17B4-induced HCC cell proliferation, and the activation of STAT3, AKT, and MEK/ERK signaling pathways. We measured the effect of HSD17B4 on the growth of transplanted tumor and the inhibitory effect of VK2. Our results indicated that VK2 directly binds to HSD17B4, but does not affect the expression of HSD17B4, to inhibit the proliferation of HCC cells by inhibiting the activation of Akt and MEK/ERK signaling pathways, leading to decreased STAT3 activation. VK2 also inhibited the growth of HSD17B4-induced transplanted tumors. These findings provide a theoretical and experimental basis for possible future prevention and treatment of HCC using VK2.

HN1 interacts with γ-tubulin to regulate centrosomes in advanced prostate cancer cells

Prostate cancer is one of the most common cancer for men worldwide with advanced forms showing supernumerary or clustered centrosomes. Hematological and neurological expressed 1 (HN1) also known as Jupiter Microtubule Associated Homolog 1 (JPT1) belongs to a small poorly understood family of genes that are evolutionarily conserved across vertebrate species. The co-expression network of HN1 from the TCGA PRAD dataset indicates the putative role of HN1 in centrosome-related processes in the context of prostate cancer. HN1 expression is low in normal RWPE-1 cells as compared to cancerous androgen-responsive LNCaP and androgen insensitive PC-3 cells. HN1 overexpression resulted in differential response for cell proliferation and cell cycle changes in RWPE-1, LNCaP, and PC-3 cells. Since HN1 overexpression increased the proliferation rate in PC-3 cells, these cells were used for functional characterization of HN1 in advanced prostate carcinogenesis. Furthermore, alterations in HN expression led to an increase in abnormal to normal nuclei ratio and increased chromosomal aberrations in PC-3 cells. We observed the co-localization of HN1 with γ-tubulin foci in prostate cancer cells, further validated by immunoprecipitation. HN1 was observed as physically associated with γ-tubulin and its depletion led to increased γ-tubulin foci and disruption in microtubule spindle assembly. Higher HN1 expression was correlated with prostate cancer as compared to normal tissues. The restoration of HN1 expression after silencing suggested that it has a role in centrosome clustering, implicating a potential role of HN1 in cell division as well as in prostate carcinogenesis warranting further studies.

High expression of regulator of G-protein signalling 1 is associated with the poor differentiation and prognosis of gastric cancer

Emerging evidence has highlighted that immune and stromal cells form the majority of the tumour microenvironment (TME), which plays important roles in tumour progression. The present study aimed to screen vital prognostic genes associated with the TME in gastric cancer (GC). The ESTIMATE algorithm was applied to calculate TME-related scores, and the relationship between clinicopathological variables and these scores was analysed. Heatmaps and Venn plots were then used to visualize and screen differentially expressed genes. Furthermore, functional enrichment analysis was performed, and a protein-protein interaction network was constructed. Kaplan-Meier curves were generated to evaluate survival differences for each hub gene. Reverse transcription quantitative PCR was employed to evaluate the expression of the three hub genes in the validation cohort. The association between gene expression, clinicopathological variables and survival was also evaluated. Higher stromal scores were associated with worse outcomes in patients with GC. In addition, higher scores were significantly associated with a higher tumour grade, American Joint Committee on Cancer stage and T stage with regard to immune scores, stromal scores and ESTIMATE scores, respectively. In total, 644 upregulated intersecting genes and 126 downregulated genes were identified. Moreover, 71 TME-associated hub genes were identified. Batch survival analysis revealed that higher expression of CXCR4, PTGFR and RGS1 was significantly associated with worse outcome. Subsequently, the relationship between high expression of RGS1 and poor prognosis was verified, and high expression of RGS1 was associated with poor differentiation. In conclusion, it was found that compared with immune cells, stromal cells may play a more important role in the prognosis of patients with GC. In addition, the influence of RGS1 expression on survival in GC patients was identified and verified, and high expression of RGS1 was found to be associated with a low differentiation degree of GC.

Rs145204276 and rs4759314 affect the prognosis of prostate cancer by modulating the GAS5/miR-1284/HMGB1 and HOTAIR/miR-22/HMGB1 signalling pathways

Non-coding RNAs play an important role in the pathogenesis of prostate cancer (PC). This study aims to characterize the role of GAS5 rs145204276 and HOTAIR rs4759314 polymorphisms in the pathogenesis of PC. Both INS allele of GAS5 rs145204276 and A allele of HOTAIR rs4759314 were identified to increase the survival of PC patients. And patients carrying DEL/DEL + AG genotypes tend to present higher levels of HMGB1, GAS5, HOTAIR and lower levels of miR-1284 and miR-22. In addition, the transcription activity of GAS5 promoter was increased by the deletion allele of rs145204276 polymorphism, while the G allele of rs4759314 polymorphism increased the transcription activity of HOTAIR promoter. GAS5 and HOTAIR could bind to miR-1284 and miR-22, respectively, while miR-1284 and miR-22 could bind to the 3'UTR of HMGB1. Compared with the control group, the expressions of miR-1284 or miR-22 were decreased with the presence of GAS5 or HOTAIR, and the expression of HMGB1 was the highest in the GAS5 + HOTAIR group. In summary, the findings of this study demonstrated that both GAS5 rs145204276 and HOTAIR rs4759314 polymorphisms could affect the prognosis of PC by modulating the expression of HMGB1 via modulating the GAS5/miR-1284/HMGB1 and HOTAIR/miR-22/HMGB1 signalling pathways.

MicroRNAs in treatment-induced neuroendocrine differentiation in prostate cancer

Prostate cancer is a condition commonly associated with men worldwide. Androgen deprivation therapy remains one of the targeted therapies. However, after some years, there is biochemical recurrence and metastatic progression into castration-resistant prostate cancer (CRPC). CRPC cases are treated with second-line androgen deprivation therapy, after which, these CRPCs transdifferentiate to form neuroendocrine prostate cancer (NEPC), a highly aggressive variant of CRPC. NEPC arises via a reversible transdifferentiation process, known as neuroendocrine differentiation (NED), which is associated with altered expression of lineage markers such as decreased expression of androgen receptor and increased expression of neuroendocrine lineage markers including enolase 2, chromogranin A and synaptophysin. The etiological factors and molecular basis for NED are poorly understood, contributing to a lack of adequate molecular biomarkers for its diagnosis and therapy. Therefore, there is a need to fully understand the underlying molecular basis for this cancer. Recent studies have shown that microRNAs (miRNAs) play a key epigenetic role in driving therapy-induced NED in prostate cancer. In this review, we briefly describe the role of miRNAs in prostate cancer and CRPCs, discuss some key players in NEPCs and elaborate on miRNA dysregulation as a key epigenetic process that accompanies therapy-induced NED in metastatic CRPC. This understanding will contribute to better clinical management of the disease.

Long Non-Coding Small Nucleolar RNA Host Genes (SNHGs) in Endocrine-Related Cancers

Long non-coding RNAs (lncRNAs) are emerging regulators of a diverse range of biological processes through various mechanisms. Genome-wide association studies of tumor samples have identified several lncRNAs, which act as either oncogenes or tumor suppressors in various types of cancers. Small nucleolar RNAs (snoRNAs) are predominantly found in the nucleolus and function as guide RNAs for the processing of transcription. As the host genes of snoRNAs, lncRNA small nucleolar RNA host genes (SNHGs) have been shown to be abnormally expressed in multiple cancers and can participate in cell proliferation, tumor progression, metastasis, and chemoresistance. Here, we review the biological functions and emerging mechanisms of SNHGs involved in the development and progression of endocrine-related cancers including thyroid cancer, breast cancer, pancreatic cancer, ovarian cancer and prostate cancer.

Analysis of the developmental expression of small VCP-interacting protein and its interaction with steroidogenic acute regulatory protein in Leydig cells

Small VCP-interacting protein (SVIP) is a 9-kDa protein that is composed of 76 amino acids, and it plays a role in the endoplasmic reticulum-associated protein degradation (ERAD) pathway. Recent studies have shown that SVIP is an androgen-responsive protein and its expression is regulated by androgens. Because no data are available regarding the cellular localization and expression of SVIP in the mouse testis, where androgens are highly expressed, immunohistochemistry and western blotting were performed. In the fetal testis, we found that moderate but consistent staining of SVIP is present in the cytoplasm of Leydig cells. In prepubertal and adult life, SVIP remains present in Leydig cells as well as in the cytoplasm of some peritubular and Sertoli cells. From postnatal day 15 onward, SVIP is strongly expressed in the cytoplasm of Leydig cells. Furthermore, TM3, MA-10 Leydig and Sertoli cell lines were also used to evaluate the expression of SVIP. To identify the interacting partners, such as steroidogenic acute regulatory (STAR) protein, colocalization studies were performed by fluorescence microscopy, showing that STAR colocalized with SVIP in the adult mouse testis. The expression changes of STAR were studied by using SVIP siRNAs in Leydig cell line cultures. Depletion of SVIP resulted in decreased expression of STAR. Additionally, the number and size of lipid droplets were significantly increased in SVIP-depleted Leydig cells. Taken together, our data identify SVIP as a marker of Leydig cell lineage and as a regulator of STAR protein expression and lipid droplet status in Leydig cells.

Overexpression of PSMA7 predicts poor prognosis in patients with gastric cancer

Gastric cancer (GC) is the fourth most common tumor and the second most common cause of cancer-associated mortality worldwide. Current tumor biomarkers for GC, such as serum carcinoembryonic antigen and carbohydrate antigen 19-9, are not ideal due to their limited role as prognostic indicators for GC. Proteasome subunit α7 (PSMA7) is a multifunctional protein, which has been revealed to be involved in the development and progression of various types of malignancy. However, little is known about the role of PSMA7 in GC. In the present study, PSMA7 was identified to be overexpressed at the mRNA and protein levels in GC tissues, compared with in non-tumor tissues, using reverse transcription-quantitative PCR and immunohistochemistry. Furthermore, PSMA7 expression is associated with tumor invasion, lymph node metastasis, distant metastasis, and Tumor-Node-Metastasis stage. Univariate and multivariate Cox regression analysis identified that PSMA7 expression is an independent prognostic factor for poor survival. Kaplan-Meier survival curves revealed that high PSMA7 expression is associated with a poor prognosis in patients with GC. Overall, the results of the present study suggested that PSMA7 may be a promising biomarker for the prognosis of GC, and may represent a new diagnostic marker and molecular therapeutic target for GC.

The Redox Role of G6PD in Cell Growth, Cell Death, and Cancer

The generation of reducing equivalent NADPH via glucose-6-phosphate dehydrogenase (G6PD) is critical for the maintenance of redox homeostasis and reductive biosynthesis in cells. NADPH also plays key roles in cellular processes mediated by redox signaling. Insufficient G6PD activity predisposes cells to growth retardation and demise. Severely lacking G6PD impairs embryonic development and delays organismal growth. Altered G6PD activity is associated with pathophysiology, such as autophagy, insulin resistance, infection, inflammation, as well as diabetes and hypertension. Aberrant activation of G6PD leads to enhanced cell proliferation and adaptation in many types of cancers. The present review aims to update the existing knowledge concerning G6PD and emphasizes how G6PD modulates redox signaling and affects cell survival and demise, particularly in diseases such as cancer. Exploiting G6PD as a potential drug target against cancer is also discussed.

Long non-coding RNAs in prostate cancer: Functional roles and clinical implications

Long noncoding RNAs (lncRNAs) are defined as RNA transcripts longer than 200 nucleotides that do not encode proteins. LncRNAs have been documented to exhibit aberrant expression in various types of cancer, including prostate cancer. Currently, screening for prostate cancer results in overdiagnosis. The consequent overtreatment of patients with indolent disease in the clinic is due to the lack of appropriately sensitive and specific biomarkers. Thus, the identification of lncRNAs as novel biomarkers and therapeutic targets for prostate cancer is promising. In the present review, we attempt to summarize the current knowledge of lncRNA expression patterns and mechanisms in prostate cancer. In particular, we focus on lncRNAs regulated by the androgen receptor and the specific molecular mechanism of lncRNAs in prostate cancer to provide a potential clinical therapeutic strategy for prostate cancer.

Transcriptomics Signature from Next-Generation Sequencing Data Reveals New Transcriptomic Biomarkers Related to Prostate Cancer

Prostate cancer is one of the most common types of cancer among Canadian men. Next-generation sequencing using RNA-Seq provides large amounts of data that may reveal novel and informative biomarkers. We introduce a method that uses machine learning techniques to identify transcripts that correlate with prostate cancer development and progression. We have isolated transcripts that have the potential to serve as prognostic indicators and may have tremendous value in guiding treatment decisions. Analysis of normal versus malignant prostate cancer data sets indicates differential expression of the genes HEATR5B, DDC, and GABPB1-AS1 as potential prostate cancer biomarkers. Our study also supports PTGFR, NREP, SCARNA22, DOCK9, FLVCR2, IK2F3, USP13, and CLASP1 as potential biomarkers to predict prostate cancer progression, especially between stage II and subsequent stages of the disease.

Long non-coding RNA GAS5 promotes PC12 cells differentiation into Tuj1-positive neuron-like cells and induces cell cycle arrest

Growth arrest-specific 5 (GAS5) is an anti-oncogene that has been extensively studied in tumors. However, research on GAS5 in the context of nervous system disease is rare at present. This study aimed to investigate the role of the long non-coding RNA GAS5 in rat pheochromocytoma cells (PC12 cells). GAS5-overexpressing lentivirus was transfected into PC12 cells, and expression levels of GAS5 and C-myc were detected by real-time PCR. Ratios of cells in S phase were detected by 5-ethynyl-2′-deoxyuridine. Immunohistochemical staining was used to detect the immunoreactivity of neuron microtubule markers Tuj1, doublecortin, and microtubule-associated protein 2. Apoptosis was detected by flow cytometry, while expression of acetylcholine in cells was detected by western blot assay. We found that GAS5 can promote PC12 cells to differentiate into Tuj1-positive neuron-like cells with longer processes. In addition, cell proliferation and cell cycle were significantly suppressed by GAS5, whereas it had no effect on apoptosis of PC12 cells. Our results indicate that GAS5 could increase the expression of choline acetyltransferase and acetylcholine release. Thus, we speculate that GAS5 is beneficial to the recovery of neurons and the cholinergic nervous system.

LncRNA GAS5 regulates redox balance and dysregulates the cell cycle and apoptosis in malignant melanoma cells

PURPOSE

Clinical outcomes for advanced malignant melanoma (MM) are often poor due to tumor invasiveness, metastasis, recurrence, and multidrug resistance.

METHODS

We investigated whether apoptosis, cell cycle regulation, oxidative status, and redox balance were altered by changes in the expression of the long noncoding RNA, growth arrest-specific transcript 5 (GAS5), in MM cells.

RESULTS

Analysis of clinical samples from MM patients showed that the rate of reduced GAS5 expression, relative to that in adjacent noncancerous tissues, was significantly lower for tumors from patients with advanced disease (76.6%, P < 0.001), as evidenced by larger tumor size, higher TNM stage, and higher incidences of ulceration and metastasis (P < 0.001 for all). Cell culture experiments showed that siRNA-mediated knockdown of GAS5 increased the viability of A375-GAS5si cells. Flow cytometry and western blotting showed that GAS5 knockdown increased MM cell proliferation by inducing G1/S cell cycle progression through increases in Cyclin D1, CDK4, and p27 expression (P < 0.05 for all) and by inhibiting apoptosis through an increase in Bcl-2 expression (P < 0.001). Knockdown of GAS5 also increased levels of superoxide anion (P < 0.01), NADP⁺(P < 0.001), and oxidized glutathiones (P < 0.01) through increases in NOX4 expression (P < 0.001), G6PD expression (P < 0.01), and NOX activity (P < 0.05), and RNA co-immunoprecipitation showed that GAS5 induced these changes through a physical interaction between GAS5 and the G6PD protein.

CONCLUSIONS

Our findings show GAS5 contributes to regulation of the apoptosis, cell cycle, homeostasis of reactive oxygen species, and redox balance in MM cells, and suggest that reduced GAS5 expression contributes to disease progression in MM patients.

Aberrant lncRNA Expression in Multiple Myeloma

Multiple myeloma (MM), a type of malignant tumor, is characterized by dysplasia of clonal plasma cells in the bone marrow. People with MM will have damaged organs or tissues due to secretion of large amounts of monoclonal immunoglobulin or fragments (M protein). Despite improved survivability by novel treatment strategies over the last decade, MM is still incurable by current therapies. Long noncoding RNAs (lncRNAs), with length of more than 200 nucleotides, have been reported to act as important regulators in many diseases, including MM. Recent studies have reported aberrant lncRNA expression in MM; these dysregulated lncRNAs can play oncogenic and/or tumor-suppressive roles in the development and progression of MM. In this article, we present a general overview on the role of lncRNAs in MM pathogenesis and discuss their potential as prognostic biomarkers and targets for treatment.

The identification of new substrates of human DHRS7 by molecular modeling and in vitro testing

Human DHRS7 (SDR34C1) is one of insufficiently described enzymes of the short-chain dehydrogenase/reductase superfamily. The members of this superfamily often play an important pato/physiological role in the human body, participating in the metabolism of diverse substrates (e.g. retinoids, steroids, xenobiotics). A systematic approach to the identification of novel, physiological substrates of DHRS7 based on a combination of homology modeling, structure-based virtual screening and experimental evaluation has been used. Three novel substrates of DHRS7 (dihydrotestosterone, benzil and 4,4'-dimetylbenzil) have been described.

DHRS7 (SDR34C1) - A new player in the regulation of androgen receptor function by inactivation of 5α-dihydrotestosterone?

DHRS7 (SDR34C1) has been associated with potential tumor suppressor effects in prostate cancer; however, its function remains largely unknown. Recent experiments using purified recombinant human DHRS7 suggested several potential substrates, including the steroids cortisone and Δ4-androstene-3,17-dione (androstenedione). However, the substrate and cofactor concentrations used in these experiments were very high and the physiological relevance of these observations needed to be further investigated. In the present study, recombinant human DHRS7 was expressed in intact HEK-293 cells in order to investigate whether glucocorticoids and androgens serve as substrates at sub-micromolar concentrations and at physiological cofactor concentrations. Furthermore, the membrane topology of DHRS7 was revisited using redox-sensitive green-fluorescent protein fusions in living cells. The results revealed that (1) cortisone is a substrate of DHRS7; however, it is not reduced to cortisol but to 20β-dihydrocortisone, (2) androstenedione is not a relevant substrate of DHRS7, (3) DHRS7 catalyzes the oxoreduction of 5α-dihydrotestosterone (5αDHT) to 3α-androstanediol (3αAdiol), with a suppressive effect on androgen receptor (AR) transcriptional activity, and (4) DHRS7 is anchored in the endoplasmic reticulum membrane with a cytoplasmic orientation. Together, the results show that DHRS7 is a cytoplasmic oriented enzyme exhibiting 3α/20β-hydroxysteroid dehydrogenase activity, with a possible role in the modulation of AR function. Further research needs to address the physiological relevance of DHRS7 in the inactivation of 5αDHT and AR regulation.

Src promotes castration-recurrent prostate cancer through androgen receptor-dependent canonical and non-canonical transcriptional signatures

Progression of prostate cancer (PC) to castration-recurrent growth (CRPC) remains dependent on sustained expression and transcriptional activity of the androgen receptor (AR). A major mechanism contributing to CRPC progression is through the direct phosphorylation and activation of AR by Src-family (SFK) and ACK1 tyrosine kinases. However, the AR-dependent transcriptional networks activated by Src during CRPC progression have not been elucidated. Here, we show that activated Src (Src527F) induces androgen-independent growth in human LNCaP cells, concomitant with its ability to induce proliferation/survival genes normally induced by dihydrotestosterone (DHT) in androgen-dependent LNCaP and VCaP cells. Src induces additional gene signatures unique to CRPC cell lines, LNCaP-C4-2 and CWR22Rv1, and to CRPC LuCaP35.1 xenografts. By comparing the Src-induced AR-cistrome and/or transcriptome in LNCaP to those in CRPC and LuCaP35.1 tumors, we identified an 11-gene Src-regulated CRPC signature consisting of AR-dependent, AR binding site (ARBS)-associated genes whose expression is altered by DHT in LNCaP[Src527F] but not in LNCaP cells. The differential expression of a subset (DPP4, BCAT1, CNTNAP4, CDH3) correlates with earlier PC metastasis onset and poorer survival, with the expression of BCAT1 required for Src-induced androgen-independent proliferation. Lastly, Src enhances AR binding to non-canonical ARBS enriched for FOXO1, TOP2B and ZNF217 binding motifs; cooperative AR/TOP2B binding to a non-canonical ARBS was both Src- and DHT-sensitive and correlated with increased levels of Src-induced phosphotyrosyl-TOP2B. These data suggest that CRPC progression is facilitated via Src-induced sensitization of AR to intracrine androgen levels, resulting in the engagement of canonical and non-canonical ARBS-dependent gene signatures.

Androgen Mediated Regulation of Endoplasmic Reticulum-Associated Degradation and its Effects on Prostate Cancer

The endoplasmic reticulum (ER) comprises thirty percent of the newly translated proteins in eukaryotic cells. The quality control mechanism within the ER distinguishes between properly and improperly folded proteins and ensures that unwanted proteins are retained in the ER and subsequently degraded through ER-associated degradation (ERAD). Besides cleaning of misfolded proteins ERAD is also important for physiological processes by regulating the abundance of normal proteins of the ER. Thus it is important to unreveal the regulation patterns of ERAD. Here, we describe that ERAD pathway is regulated by androgen, where its inhibitor SVIP was downregulated, all other ERAD genes were upregulated. Consistently, androgen treatment increased the degradation rate of ERAD substrates. Using several independent techniques, we showed that this regulation is through androgen receptor transactivation. ERAD genes found to be upregulated in prostate cancer tissues and silencing expression of Hrd1, SVIP, and gp78 reduced the in vitro migration and malignant transformation of LNCaP cells. Our data suggests that expression levels of ERAD components are regulated by androgens, that promotes ERAD proteolytic activity, which is positively related with prostate tumorigenesis.

Epigenomic Regulation of Androgen Receptor Signaling: Potential Role in Prostate Cancer Therapy

Androgen receptor (AR) signaling remains the major oncogenic pathway in prostate cancer (PCa). Androgen-deprivation therapy (ADT) is the principle treatment for locally advanced and metastatic disease. However, a significant number of patients acquire treatment resistance leading to castration resistant prostate cancer (CRPC). Epigenetics, the study of heritable and reversible changes in gene expression without alterations in DNA sequences, is a crucial regulatory step in AR signaling. We and others, recently described the technological advance Chem-seq, a method to identify the interaction between a drug and the genome. This has permitted better understanding of the underlying regulatory mechanisms of AR during carcinogenesis and revealed the importance of epigenetic modifiers. In screening for new epigenomic modifiying drugs, we identified SD-70, and found that this demethylase inhibitor is effective in CRPC cells in combination with current therapies. The aim of this review is to explore the role of epigenetic modifications as biomarkers for detection, prognosis, and risk evaluation of PCa. Furthermore, we also provide an update of the recent findings on the epigenetic key processes (DNA methylation, chromatin modifications and alterations in noncoding RNA profiles) involved in AR expression and their possible role as therapeutic targets.

MALAT1 and HOTAIR Long Non-Coding RNAs Play Opposite Role in Estrogen-Mediated Transcriptional Regulation in Prostate Cancer Cells

In the complex network of nuclear hormone receptors, the long non-coding RNAs (lncRNAs) are emerging as critical determinants of hormone action. Here we investigated the involvement of selected cancer-associated lncRNAs in Estrogen Receptor (ER) signaling. Prior studies by Chromatin Immunoprecipitation (ChIP) Sequencing showed that in prostate cancer cells ERs form a complex with the endothelial nitric oxide synthase (eNOS) and that in turn these complexes associate with chromatin in an estrogen-dependent fashion. Among these associations (peaks) we focused our attention on those proximal to the regulatory region of HOTAIR and MALAT1. These transcripts appeared regulated by estrogens and able to control ERs function by interacting with ERα/ERβ as indicated by RNA-ChIP. Further studies performed by ChIRP revealed that in unstimulated condition, HOTAIR and MALAT1 were present on pS2, hTERT and HOTAIR promoters at the ERE/eNOS peaks. Interestingly, upon treatment with17β-estradiol HOTAIR recruitment to chromatin increased significantly while that of MALAT1 was reduced, suggesting an opposite regulation and function for these lncRNAs. Similar results were obtained in cells and in an ex vivo prostate organotypic slice cultures. Overall, our data provide evidence of a crosstalk between lncRNAs, estrogens and estrogen receptors in prostate cancer with important consequences on gene expression regulation.

LncRNA GAS5 inhibits proliferation and progression of prostate cancer by targeting miR-103 through AKT/mTOR signaling pathway

In prior research, evidence has been found for a relation between low exposure of long non-coding RNAs (lncRNAs) and prostate tumor genesis. This study aims to clarify the underlying mechanisms of lncRNA GAS5 in prostate cancer (PCa). In total, 118 pairs of PCa tissues and matched adjacent non-tumor tissues were collected. Additionally, lncRNA GAS5 exposure levels were determined using RT-PCR and in situ hybridization. In addition, dual-luciferase report assay was performed to verify the target effect of lncRNA GAS5 on miR-103. The exposure levels of the proteins related to the protein kinase B (AKT)/mammalian target of rapamycin (mTOR) axis, including AKT, mTOR, and S6K1, were measured by western blot PC3 cells infected with lncRNA GAS5 mimic; lncRNA GAS5 siRNA; or a combination of lncRNA and miR-103. The proliferation, invasion, and migration ability of PC3 cells after being infected were tested by MTT assay, wound healing assay, and transwell assays. Finally, nude mouse xenograft models were used to measure lncRNA GAS5 effects on prostate tumor growth in vivo. The lncRNA GAS5 levels were reduced significantly in the PCa tissues and cell lines (P < 0.05). A low exposure of lncRNA GAS5 caused AKT/mTOR signaling pathway activation in PC3 cells (P < 0.05). In addition, over-exposure of lncRNA GAS5 was proven to significantly decelerate PCa cell progression in vitro and tumor growth in vivo through inactivating the AKT/mTOR signaling pathway (P < 0.05). This study proves that lncRNA GAS5 plays a significant role in the decelerating PCa development via mediating the AKT/mTOR signaling pathway through targeting miR-103.

Regulation of PCGEM1 by p54/nrb in prostate cancer

PCGEM1 is a long non-coding RNA (lncRNA) that is often upregulated in prostate cancer. However, little is known how PCGEM1 is regulated. In the present study, we show transcriptional regulation of PCGEM1 in response to androgen deprivation by p54/nrb. While ectopic expression of p54/nrb increases, suppression of p54/nrb by RNAi or knockout (KO) reduces PCGEM1. Moreover, rescue experiments indicate that re-expression of p54/nrb in KO cells restores the ability to induce PCGEM1, leading to upregulation of the androgen receptor splice variant AR3 which has been shown to play a role in castration resistance. Finally, 3,3′-Diindolylmethane (DIM), a known chemoprevention agent, is capable of suppressing PCGEM1 expression by preventing the interaction of p54/nrb with the PCGEM1 promoter. In particular, DIM reduces tumor growth by suppression of PCGEM1 and promoting apoptosis in the castrated xenograft mouse model. Together, these results demonstrate a novel mechanism of p54/nrb-mediated expression of PCGEM1 and AR3, contributing to castration resistance in prostate cancer.

Modulation of long noncoding RNAs by risk SNPs underlying genetic predispositions to prostate cancer

Long noncoding RNAs (lncRNAs) represent an attractive class of candidates to mediate cancer risk. Through integrative analysis of the lncRNA transcriptome with genomic data and SNP data from prostate cancer genome-wide association studies (GWAS), we identified 45 candidate lncRNAs associated with risk to prostate cancer. We further evaluated the mechanism underlying the top hit, PCAT1, and found that a risk-associated variant at rs7463708 increases binding of ONECUT2, a novel androgen receptor (AR)-interacting transcription factor, at a distal enhancer that loops to the PCAT1 promoter, resulting in upregulation of PCAT1 upon prolonged androgen treatment. In addition, PCAT1 interacts with AR and LSD1 and is required for their recruitment to the enhancers of GNMT and DHCR24, two androgen late-response genes implicated in prostate cancer development and progression. PCAT1 promotes prostate cancer cell proliferation and tumor growth in vitro and in vivo. These findings suggest that modulating lncRNA expression is an important mechanism for risk-associated SNPs in promoting prostate transformation.

Long Noncoding RNAs as Targets and Regulators of Nuclear Receptors

Intensive research has been directed at the discovery, biogenesis, and expression patterns of long noncoding RNAs , yet their biochemical functions have remained elusive for the most part. Nuclear receptors that interpret signaling mediated by small molecule hormones play a role in regulating the expression of some long noncoding RNAs. More importantly, these RNAs have also been shown to effect hormone-affected gene transcription regulated by the nuclear receptors. In this chapter, we summarize the current knowledge that has been acquired on hormonal signaling inducing expression of long noncoding RNAs and how they then may act in trans or in cis to modulate gene transcription. We highlight a few of these noncoding RNA molecules in terms of how they may impact hormone-driven cancers. Future directions critical for moving this field forward are presented, with a clear emphasis on the need for better biochemical approaches to address the mechanism of action of these exciting RNAs.

Identification of novel genes that regulate androgen receptor signaling and growth of androgen-deprived prostate cancer cells

Prostate cancer progression to castration refractory disease is associated with anomalous transcriptional activity of the androgen receptor (AR) in an androgen-depleted milieu. To identify novel gene products whose downregulation transactivates AR in prostate cancer cells, we performed a screen of enzymatically-generated shRNA lenti-libraries selecting for transduced LNCaP cells with elevated expression of a fluorescent reporter gene under the control of an AR-responsive promoter. The shRNAs present in selected populations were analyzed using high-throughput sequencing to identify target genes. Highly enriched gene targets were then validated with siRNAs against selected genes, testing first for increased expression of luciferase from an AR-responsive promoter and then for altered expression of endogenous androgen-regulated genes in LNCaP cells. We identified 20 human genes whose silencing affected the expression of exogenous and endogenous androgen-responsive genes in prostate cancer cells grown in androgen-depleted medium. Knockdown of four of these genes upregulated the expression of endogenous AR targets and siRNAs targeting two of these genes (IGSF8 and RTN1) enabled androgen-independent proliferation of androgen-dependent cells. The effects of IGSF8 appear to be mediated through its interaction with a tetraspanin protein, CD9, previously implicated in prostate cancer progression. Remarkably, homozygous deletions of IGSF8 are found almost exclusively in prostate cancers but not in other cancer types. Our study shows that androgen independence can be achieved through the inhibition of specific genes and reveals a novel set of genes that regulate AR signaling in prostate cancers.

Assembly of an Evolutionarily Conserved Alternative Proteasome Isoform in Human Cells

Targeted intracellular protein degradation in eukaryotes is largely mediated by the proteasome. Here, we report the formation of an alternative proteasome isoform in human cells, previously found only in budding yeast, that bears an altered subunit arrangement in the outer ring of the proteasome core particle. These proteasomes result from incorporation of an additional α4 (PSMA7) subunit in the position normally occupied by α3 (PSMA4). Assembly of "α4-α4" proteasomes depends on the relative cellular levels of α4 and α3 and on the proteasome assembly chaperone PAC3. The oncogenic tyrosine kinases ABL and ARG and the tumor suppressor BRCA1 regulate cellular α4 levels and formation of α4-α4 proteasomes. Cells primed to assemble α4-α4 proteasomes exhibit enhanced resistance to toxic metal ions. Taken together, our results establish the existence of an alternative mammalian proteasome isoform and suggest a potential role in enabling cells to adapt to environmental stresses.

Long non-coding RNA: A newly deciphered "code" in prostate cancer

As one of the most frequently diagnosed cancers in males, the development and progression of prostate cancer remains an open area of research. The role of lncRNAs in prostate cancer is an emerging field of study. In this review, we summarize what is currently known about lncRNAs in prostate cancer while focusing on a few key lncRNAs. PCA3 was the first lncRNA identified in prostate cancer and has been shown to be expressed in a majority of prostate cancer cases. It may act in both an androgen dependent and independent fashion and has clinical utility as a biomarker. Other lncRNAs are known to interact directly with the androgen receptor pathway including PlncRNA-1, HOTAIR, PRNCR1 and PCGEM1. Additionally, lncRNAs have been shown to interfere with tumor suppressors, DNA break repair, transcription and alternate RNA splicing. While only in its infancy, an understanding of the role of lncRNAs in prostate cancer development should present ample opportunities for the discovery of new cancer biomarkers and therapeutic targets.

Lentiviral-mediated overexpression of long non-coding RNA GAS5 reduces invasion by mediating MMP2 expression and activity in human melanoma cells

The present study evaluated the effects of long non-coding RNA GAS5 on the migration and invasion of melanoma cells. Using the SK-Mel‑110 melanoma cell line, we stably expressed GAS5, visualized the distribution of GAS5 by RNA fluorescence in situ hybridization (FISH) and examined changes in cell migration and invasion with Transwell assays. In GAS5 overexpressed SK-Mel‑110 cells, migrated and invaded cells decreased by 65.3 and 55.6%, respectively. Moreover, the MMP2 protein level, and its activity was downregulated by 67.9 and 15.8%, respectively. Overexpressing lncRNA GAS5 inhibited the migration and invasion ability of melanoma SK-Mel‑110 cells, partially by decreasing the MMP2 expression and its activity. This study is the first to reveal a potential relationship between lncRNA GAS5 and the migration and invasion of melanoma.

Human DHRS7, promising enzyme in metabolism of steroids and retinoids?

The metabolism of steroids and retinoids has been studied in detail for a long time, as these compounds are involved in a broad spectrum of physiological processes. Many enzymes participating in the conversion of such compounds are members of the short-chain dehydrogenase/reductase (SDR) superfamily. Despite great effort, there still remain a number of poorly characterized SDR proteins. According to various bioinformatics predictions, many of these proteins may play a role in the metabolism of steroids and retinoids. Dehydrogenase/reductase (SDR family) member 7 (DHRS7) is one such protein. In a previous study, we determined DHRS7 to be an integral membrane protein of the endoplasmic reticulum facing the lumen which has shown at least in vitro NADPH-dependent reducing activity toward several eobiotics and xenobiotics bearing a carbonyl moiety. In the present paper pure DHRS7 was used for a more detailed study of both substrate screening and an analysis of kinetics parameters of the physiologically important substrates androstene-3,17-dione, cortisone and all-trans-retinal. Expression patterns of DHRS7 at the mRNA as well as protein level were determined in a panel of various human tissue samples, a procedure that has enabled the first estimation of the possible biological function of this enzyme. DHRS7 is expressed in tissues such as prostate, adrenal glands, liver or intestine, where its activity could be well exploited. Preliminary indications show that DHRS7 exhibits dual substrate specificity recognizing not only steroids but also retinoids as potential substrates and could be important in the metabolism of these signalling molecules.

A role for the dehydrogenase DHRS7 (SDR34C1) in prostate cancer

Several microarray studies of prostate cancer (PCa) samples have suggested altered expression of the "orphan" enzyme short-chain dehydrogenase/reductase DHRS7 (retSDR4, SDR34C1). However, the role of DHRS7 in PCa is largely unknown and the impact of DHRS7 modulation on cancer cell properties has not yet been studied. Here, we investigated DHRS7 expression in normal human prostate and PCa tissue samples at different tumor grade using tissue microarray and immunovisualization. Moreover, we characterized the effects of siRNA-mediated DHRS7 knockdown on the properties of three distinct human prostate cell lines. We found that DHRS7 protein expression decreases alongside tumor grade, as judged by the Gleason level, in PCa tissue samples. The siRNA-mediated knockdown of DHRS7 expression in the human PCa cell lines LNCaP, BPH1, and PC3 significantly increased cell proliferation in LNCaP cells as well as cell migration in all of the investigated cell lines. Furthermore, cell adhesion was decreased upon DHRS7 knockdown in all three cell lines. To begin to understand the mechanisms underlying the effects of DHRS7 depletion, we performed a microarray study with samples from LNCaP cells treated with DHRS7-specific siRNA. Several genes involved in cell proliferation and adhesion pathways were found to be altered in DHRS7-depleted LNCaP cells. Additionally, genes of the BRCA1/2 pathway and the epithelial to mesenchymal transition regulator E-cadherin were altered following DHRS7 knockdown. Based on these results, further research is needed to evaluate the potential role of DHRS7 as a tumor suppressor and whether its loss-of-function promotes PCa progression and metastasis.

Long non-coding RNA growth arrest-specific transcript 5 in tumor biology

The recognition of the biological relevance of long non-coding RNA (lncRNA) molecules has only recently been recognized as one of the most significant advances in contemporary molecular biology. A growing body of evidence indicates that lncRNAs act not only as the intermediary between DNA and protein but also as significant protagonists of cellular functions. The dysregulation of lncRNAs has increasingly been linked to numerous human diseases, particularly cancers. Recent studies have demonstrated that the lncRNA growth arrest-specific transcript 5 (GAS5) was pervasively downexpressed in most human cancers compared with non-cancerous adjacent tissues including gastric, breast, lung and prostate cancer. In addition, patients with decreased GAS5 expression have a significantly poorer prognosis than those with higher expression. Furthermore, GAS5 is involved in the control of cell apoptosis, proliferation, metastasis, angiogenesis, DNA repair and tumor cell metabolism. This review provides an overview of the current knowledge concerning the role of GAS5 in tumor expression and biology function.

Molecular and Cellular Mechanisms of Action of Tumour Suppressor GAS5 LncRNA

It is increasingly recognised that lncRNAs play essential regulatory roles in fundamental biological processes and, consequently, that their dysregulation may contribute to major human diseases, including cancer. Better understanding of lncRNA biology may therefore offer new insights into pathogenetic mechanisms and thereby offer novel opportunities for diagnosis and therapy. Of particular interest in this regard is GAS5 lncRNA, which is down-regulated in multiple cancers, with expression levels related to both clinico-pathological characteristics and patient prognosis. Functional studies have further shown that GAS5 lncRNA both inhibits the proliferation and promotes the apoptosis of multiple cell types, and that together these cellular mechanisms of action are likely to form the basis of its tumour suppressor action. At the same time, advances have been made in our understanding of the molecular mechanisms of GAS5 lncRNA action in recent years, including riborepression of certain steroid hormone receptors and sequestration of miR-21, impacting key regulatory pathways of cell survival. Overall this accumulating knowledge has the potential to improve both the diagnosis and treatment of cancer, and ultimately patient outcome.