Targeting the unique methylation pattern of androgen receptor (AR) promoter in prostate stem/progenitor cells with 5-aza-2'-deoxycytidine (5-AZA) leads to suppressed prostate tumorigenesis

Regulation and signaling pathways in cancer stem cells: implications for targeted therapy for cancer

Cancer stem cells (CSCs), initially identified in leukemia in 1994, constitute a distinct subset of tumor cells characterized by surface markers such as CD133, CD44, and ALDH. Their behavior is regulated through a complex interplay of networks, including transcriptional, post-transcriptional, epigenetic, tumor microenvironment (TME), and epithelial-mesenchymal transition (EMT) factors. Numerous signaling pathways were found to be involved in the regulatory network of CSCs. The maintenance of CSC characteristics plays a pivotal role in driving CSC-associated tumor metastasis and conferring resistance to therapy. Consequently, CSCs have emerged as promising targets in cancer treatment. To date, researchers have developed several anticancer agents tailored to specifically target CSCs, with some of these treatment strategies currently undergoing preclinical or clinical trials. In this review, we outline the origin and biological characteristics of CSCs, explore the regulatory networks governing CSCs, discuss the signaling pathways implicated in these networks, and investigate the influential factors contributing to therapy resistance in CSCs. Finally, we offer insights into preclinical and clinical agents designed to eliminate CSCs.

Epigenetic mechanism of therapeutic resistance and potential of epigenetic therapeutics in chemorefractory prostate cancer

Prostate cancer is the second leading cause of cancer death among men in the United States. Depending upon the histopathological subtypes of prostate cancers, various therapeutic options, such as androgen deprivation therapy (ADT), androgen receptor signaling inhibitors (ARSI), immunotherapy, and chemotherapy, are available to treat prostate cancer. While these therapeutics are effective in the initial stages during treatments, the tumors subsequently develop resistance to these therapies. Despite all the progress made so far, therapeutic resistance remains a major challenge in the treatment of prostate cancer. Although various mechanisms have been reported for the resistance development in prostate cancer, altered expression of genes either directly or indirectly involved in drug response pathways is a common event. In addition to the genetic basis of gene regulation such as mutations and gene amplifications, epigenetic alterations involved in the aberrant expression of genes have frequently been shown to be associated not only with cancer initiation and progression but also with therapeutic resistance development. There are several review articles compiling reports on genetic mechanisms involved in therapeutic resistance in prostate cancer. However, epigenetic mechanisms for the therapeutic resistance development in prostate cancer have not yet been summarized in a review article. Therefore, the objective of this article is to compile various reports and provide a comprehensive review of the epigenetic aberrations, and aberrant expression of genes by epigenetic mechanisms involved in CRPCs and therapeutic resistance development in prostate cancer. Additionally, the potential of epigenetic-based therapeutics in the treatment of chemorefractory prostate cancer as evidenced by clinical trials has also been discussed.

Epigenetics in cancer development, diagnosis and therapy

Cancer is a dangerous disease and one of the leading causes of death in the world. In 2020, there were nearly 10 million cancer deaths and approximately 20 million new cases. New cases and deaths from cancer are expected to increase further in the coming years. To have a deeper insight into the mechanism of carcinogenesis, epigenetics studies have been published and received much attention from scientists, doctors, and patients. Among alterations in epigenetics, DNA methylation and histone modification are studied by many scientists. They have been reported to be a major contributor in tumor formation and are involved in metastasis. From the understanding of DNA methylation and histone modification, effective, accurate and cost-effective methods for diagnosis and screening of cancer patients have been introduced. Furthermore, therapeutic approaches and drugs targeting altered epigenetics have also been clinically studied and have shown positive results in combating tumor progression. Several cancer drugs that rely on DNA methylation inactivation or histone modification have been approved by the FDA for the treatment of cancer patients. In summary, epigenetics changes such as DNA methylation or histone modification are take part in tumor growth, and they also have great prospect to study diagnostic and therapeutic methods of this dangerous disease.

Epigenetic regulation of cancer stem cells: Shedding light on the refractory/relapsed cancers

The resistance to drugs, ability to enter quiescence and generate heterogeneous cancer cells, and enhancement of aggressiveness, make cancer stem cells (CSCs) integral part of tumor progression, metastasis and recurrence after treatment. The epigenetic modification machinery is crucial for the viability of CSCs and evolution of aggressive forms of a tumor. These mechanisms can also be targeted by specific drugs, providing a promising approach for blocking CSCs. In this review, we summarize the epigenetic regulatory mechanisms in CSCs which contribute to drug resistance, quiescence and tumor heterogeneity. We also discuss the drugs that can potentially target these processes and data from experimental and clinical studies.

Dynamic plasticity of prostate cancer intermediate cells during androgen receptor-targeted therapy

Treatment-emergent small cell neuroendocrine prostate cancer (t-SCNC) is associated with an epithelial lineage switch from an androgen receptor (AR)-positive to neuroendocrine (NE)-marker-positive status. Understanding the potential for reversibility of this aggressive disease state has been hampered by the paucity of models suitable for studying rate-limiting, transitional, or intermediate tumor cell subpopulations. We define a dual reporter model that measures acute transcriptional changes in response to castration or AR targeting agents. We identify steady-state transcriptional heterogeneity in AR and NE biomarkers, including intermediate subpopulations that are coordinately high for prostate-specific antigen (PSA) and neuron-specific enoclase (NSE) promoter activity. In the presence of castration or AR inhibitors, intermediate cells were necessary and sufficient for therapy-induced conversion of human PC cells to an NSE-high transcriptional status. Using hormone add-back studies, treatment-induced PSA-NSE transcriptional plasticity was reversible in PTEN-deficient PC cells but not in the presence of secondary genetic driver genes, including MYCN.

The metabolic addiction of cancer stem cells

Cancer stem cells (CSC) are the minor population of cancer originating cells that have the capacity of self-renewal, differentiation, and tumorigenicity (when transplanted into an immunocompromised animal). These low-copy number cell populations are believed to be resistant to conventional chemo and radiotherapy. It was reported that metabolic adaptation of these elusive cell populations is to a large extent responsible for their survival and distant metastasis. Warburg effect is a hallmark of most cancer in which the cancer cells prefer to metabolize glucose anaerobically, even under normoxic conditions. Warburg's aerobic glycolysis produces ATP efficiently promoting cell proliferation by reprogramming metabolism to increase glucose uptake and stimulating lactate production. This metabolic adaptation also seems to contribute to chemoresistance and immune evasion, a prerequisite for cancer cell survival and proliferation. Though we know a lot about metabolic fine-tuning in cancer, what is still in shadow is the identity of upstream regulators that orchestrates this process. Epigenetic modification of key metabolic enzymes seems to play a decisive role in this. By altering the metabolic flux, cancer cells polarize the biochemical reactions to selectively generate "onco-metabolites" that provide an added advantage for cell proliferation and survival. In this review, we explored the metabolic-epigenetic circuity in relation to cancer growth and proliferation and establish the fact how cancer cells may be addicted to specific metabolic pathways to meet their needs. Interestingly, even the immune system is re-calibrated to adapt to this altered scenario. Knowing the details is crucial for selective targeting of cancer stem cells by choking the rate-limiting stems and crucial branch points, preventing the formation of onco-metabolites.

From Therapy Resistance to Targeted Therapies in Prostate Cancer

Prostate cancer (PCa) is the second most common malignancy among men worldwide. Although early-stage disease is curable, advanced stage PCa is mostly incurable and eventually becomes resistant to standard therapeutic options. Different genetic and epigenetic alterations are associated with the development of therapy resistant PCa, with specific players being particularly involved in this process. Therefore, identification and targeting of these molecules with selective inhibitors might result in anti-tumoral effects. Herein, we describe the mechanisms underlying therapy resistance in PCa, focusing on the most relevant molecules, aiming to enlighten the current state of targeted therapies in PCa. We suggest that selective drug targeting, either alone or in combination with standard treatment options, might improve therapeutic sensitivity of resistant PCa. Moreover, an individualized analysis of tumor biology in each PCa patient might improve treatment selection and therapeutic response, enabling better disease management.

Epi-immunotherapy for cancers: rationales of epi-drugs in combination with immunotherapy and advances in clinical trials

Over the last two decades, several epi-drugs, immune checkpoint inhibitors (ICIs) and adoptive cell therapies have received clinical approval for use in certain types of cancer. However, monotherapy with epi-drugs or ICIs has shown limited efficacy in most cancer patients. Epigenetic agents have been shown to regulate the crosstalk between the tumor and host immunity to alleviate immune evasion, suggesting that epi-drugs can potentially synergize with immunotherapy. In this review, we discuss recent insights into the rationales of incorporating epigenetic therapy into immunotherapy, called epi-immunotherapy, and focus on an update of current clinical trials in both hematological and solid malignancies. Furthermore, we outline the future challenges and strategies in the field of cancer epi-immunotherapy.

Targeting DNMTs to Overcome Enzalutamide Resistance in Prostate Cancer

Prostate cancer is the second leading cause of cancer death among men in the United States. The androgen receptor (AR) antagonist enzalutamide is an FDA-approved drug for treatment of patients with late-stage prostate cancer and is currently under clinical study for early-stage prostate cancer treatment. After a short positive response period to enzalutamide, tumors will develop drug resistance. In this study, we uncovered that DNA methylation was deregulated in enzalutamide-resistant cells. DNMT activity and DNMT3B expression were upregulated in resistant cell lines. Enzalutamide induced the expression of DNMT3A and DNMT3B in prostate cancer cells with a potential role of p53 and pRB in this process. The overexpression of DNMT3B3, a DNMT3B variant, promoted an enzalutamide-resistant phenotype in C4-2B cell lines. Inhibition of DNA methylation and DNMT3B knockdown induced a resensitization to enzalutamide. Decitabine treatment in enzalutamide-resistant cells induced a decrease of the expression of AR-V7 and changes of genes for apoptosis, DNA repair, and mRNA splicing. Combination treatment of decitabine and enzalutamide induced a decrease of tumor weight, Ki-67 and AR-V7 expression and an increase of cleaved-caspase3 levels in 22Rv1 xenografts. The collective results suggest that DNA methylation pathway is deregulated after enzalutamide resistance onset and that targeting DNA methyltransferases restores the sensitivity to enzalutamide in prostate cancer cells.

Targeting the Lnc-OPHN1-5/androgen receptor/hnRNPA1 complex increases Enzalutamide sensitivity to better suppress prostate cancer progression

Long non-coding RNAs (lncRNAs) have been found to play critical roles in regulating gene expression, but their function in translational control is poorly understood. We found lnc-OPHN1-5, which lies close to the androgen receptor (AR) gene on chromosome X, increased prostate cancer (PCa) Enzalutamide (Enz) sensitivity via decreasing AR protein expression and associated activity. Mechanism dissection revealed that lnc-OPHN1-5 interacted with AR-mRNA to minimize its interaction with the RNA binding protein (RBP) hnRNPA1. Suppressing lnc-OPHN1-5 expression promoted the interaction between AR-mRNA and hnRNPA1, followed by an increase of ribosome association with AR-mRNA and translation. This effect was reversed by increasing lnc-OPHN1-5 expression. Consistently, the in vivo mice model confirmed that knocking down lnc-OPHN1-5 expression in tumors significantly increased the tumor formation rate and AR protein expression compared with the control group. Furthermore, knocking down hnRNPA1 blocked/reversed shlnc-OPHN1-5-increased AR protein expression and re-sensitized cells to Enz treatment efficacy. Evidence from Enz-resistant cell lines, patient-derived xenograft (PDX) models, clinical samples, and a human PCa study accordantly suggested that patients with low expression of lnc-OPHN1-5 likely have unfavorable prognoses and probably are less sensitive to Enz treatment. In summary, targeting this newly identified lnc-OPHN1-5/AR/hnRNPA1 complex may help develop novel therapies to increase Enz treatment sensitivity for suppressing the PCa at an advanced stage.

Local ablation of gastric cancer by reconstituted apolipoprotein B lipoparticles carrying epigenetic drugs

Epigenetic inhibitors have shown anticancer effects. Combination chemotherapy with epigenetic inhibitors has shown high effectiveness in gastric cancer clinical trials, but severe side effect and local progression are the causes of treatment failure. Therefore, we sought to develop an acidity-sensitive drug delivery system to release drugs locally to diminish unfavorable outcome of gastric cancer. In this study, we showed that, as compared with single agents, combination treatment with the demethylating agent 5'-aza-2'-deoxycytidine and HDAC inhibitors Trichostatin A or LBH589 decreased cell survival, blocked cell cycle by reducing number of S-phase cells and expression of cyclins, increased cell apoptosis by inducing expression of Bim and cleaved Caspase 3, and reexpressed tumor suppressor genes more effectively in MGCC3I cells. As a carrier, reconstituted apolipoprotein B lipoparticles (rABLs) could release drugs in acidic environments. Orally administrated embedded drugs not only showed inhibitory effects on gastric tumor growth in a syngeneic orthotopic mouse model, but also reduced the hepatic and renal toxicity. In conclusion, we have established rABL-based nanoparticles embedded epigenetic inhibitors for local treatment of gastric cancer, which have good therapeutic effects but do not cause severe side effects.

Cancer Stem Cells: Powerful Targets to Improve Current Anticancer Therapeutics

A frequent observation in several malignancies is the development of resistance to therapy that results in frequent tumor relapse and metastasis. Much of the tumor resistance phenotype comes from its heterogeneity that halts the ability of therapeutic agents to eliminate all cancer cells effectively. Tumor heterogeneity is, in part, controlled by cancer stem cells (CSC). CSC may be considered the reservoir of cancer cells as they exhibit properties of self-renewal and plasticity and the capability of reestablishing a heterogeneous tumor cell population. The endowed resistance mechanisms of CSC are mainly attributed to several factors including cellular quiescence, accumulation of ABC transporters, disruption of apoptosis, epigenetic reprogramming, and metabolism. There is a current need to develop new therapeutic drugs capable of targeting CSC to overcome tumor resistance. Emerging in vitro and in vivo studies strongly support the potential benefits of combination therapies capable of targeting cancer stem cell-targeting agents. Clinical trials are still underway to address the pharmacokinetics, safety, and efficacy of combination treatment. This review will address the main characteristics, therapeutic implications, and perspectives of targeting CSC to improve current anticancer therapeutics.

Downregulation of DACT-2 by Promoter Methylation and its Clinicopathological Significance in Prostate Cancer

Backgrounds: Dapper homolog (DACT) 2, a member of DACT gene family, is frequently down-regulated in various malignancies and linked to tumor progression. However, the regulatory mechanism of DACT-2 expression and its biological role in human prostate cancer (PCa) remains elusive. Here, we investigated the expression and an epigenetic change of DACT-2 in prostate cancer, and determined if these findings were correlated with clinicopathologic characteristics of PCa.

Methods: The expression profile of DACT-2 of was detected by qRT-PCR, Western blotting, and immunohistochemistry in four prostate cell lines (RWPE-1, LNCaP, PC-3 and DU145), 56 cases of frozen prostate tissues (forty-seven primary prostate carcinomas, nine paired noncancerous and cancerous prostate tissues) and a tissue microarray sets including 100 paraffin-embedded prostate samples (3 normal tissues, 2 cases of adjacent tissues and 95 cases of cancer). Subsequently, the regulatory mechanism of DACT-2 down-regulation was investigated through methylation-specific PCR (MSP) and bisulfite sequencing (BSP). The role of DACT-2 in prostate cancer cell migration and invasion was respectively examined by wound healing and transwell assay. After 5-aza-2'-deoxycytidine treatment of prostate cancer cells, qRT-PCR was used to detect whether the expression of DACT-2 gene mRNA in the cells recovered.

Results: Immunohistochemical results shown that the DACT-2 protein was strongly (3+) expressed in the cytoplasm of all 5 noncancerous tissues and 12.7% (12/95) prostate cancer (PCa) tissues. Whereas 68.4% (65/95) PCa samples and 18.9% (18/95) PCa tissues respectively displayed weakly (1+) expressed and moderately (2+) expressed. In addition, DACT-2 expression was negatively associated with Gleason score in tumor specimens (p=0.029). What's more, down-regulation and promoter methylation of DACT-2 were observed in 68.1% (32/47) frozen PCa tissues and all three prostate cancer cell lines. And, the expression of DACT-2 mRNA was restored by the treatment of demethylated drug 5-aza-2'-deoxycytidine in all prostate cancer lines. Prostate cancer cells invasion and migration were significantly suppressed by ectopic expression of DACT-2 in vitro.

Conclusions: Our study provides evidence that DACT-2 may be a useful biomarker for distinguishing prostate tumor tissues from non-cancerous samples and a potential target for epigenetic silencing in primary prostate Cancer.

Dysregulated Transcriptional Control in Prostate Cancer

Recent advances in whole-genome and transcriptome sequencing of prostate cancer at different stages indicate that a large number of mutations found in tumors are present in non-protein coding regions of the genome and lead to dysregulated gene expression. Single nucleotide variations and small mutations affecting the recruitment of transcription factor complexes to DNA regulatory elements are observed in an increasing number of cases. Genomic rearrangements may position coding regions under the novel control of regulatory elements, as exemplified by the TMPRSS2-ERG fusion and the amplified enhancer identified upstream of the androgen receptor (AR) gene. Super-enhancers are increasingly found to play important roles in aberrant oncogenic transcription. Several players involved in these processes are currently being evaluated as drug targets and may represent new vulnerabilities that can be exploited for prostate cancer treatment. They include factors involved in enhancer and super-enhancer function such as bromodomain proteins and cyclin-dependent kinases. In addition, non-coding RNAs with an important gene regulatory role are being explored. The rapid progress made in understanding the influence of the non-coding part of the genome and of transcription dysregulation in prostate cancer could pave the way for the identification of novel treatment paradigms for the benefit of patients.

Key actors in cancer therapy: epigenetic modifiers

Epigenetic reprogramming plays a crucial role in the tumorigenicity and maintenance of tumor-specific gene expression that especially occurs through DNA methylation and/or histone modifications. It has well-defined mechanisms. It is known that alterations in the DNA methylation pattern and/or the loss of specific histone acetylation/methylation markers are related to several hallmarks of cancer, such as drug resistance, stemness, epithelial-mesenchymal transition, and metastasis. It has also recently been highlighted that epigenetic alterations are critical for the regulation of the stemlike properties of cancer cells (tumor-initiating cells; cancer stem cells). Cancer stem cells are thought to be responsible for the recurrence of cancer which makes the patient return to the clinic with metastatic tumor tissue. Hence, the dysregulation of epigenetic machinery represents potential new therapeutic targets. Therefore, compounds with epigenetic activities have become crucial for developing new therapy regimens (e.g., antimetastatic agents) in the fight against cancer. Here, we review the epigenetic modifiers that have already been used in the clinic and/or in clinical trials, related preclinical studies in cancer therapy, and the smart combination strategies that target cancer stem cells along with the other cancer cells. The emerging role of epitranscriptome (RNA epigenetic) in cancer therapy has also been included in this review as a new avenue and potential target for the better management of cancer-beneficial epigenetic machinery.

DNA methylation among firefighters

Firefighters are exposed to carcinogens and have elevated cancer rates. We hypothesized that occupational exposures in firefighters would lead to DNA methylation changes associated with activation of cancer pathways and increased cancer risk. To address this hypothesis, we collected peripheral blood samples from 45 incumbent and 41 new recruit non-smoking male firefighters and analyzed the samples for DNA methylation using an Illumina Methylation EPIC 850k chip. Adjusting for age and ethnicity, we performed: 1) genome-wide differential methylation analysis; 2) genome-wide prediction for firefighter status (incumbent or new recruit) and years of service; and 3) Ingenuity Pathway Analysis (IPA). Four CpGs, including three in the YIPF6, MPST, and PCED1B genes, demonstrated above 1.5-fold statistically significant differential methylation after Bonferroni correction. Genome-wide methylation predicted with high accuracy incumbent and new recruit status as well as years of service among incumbent firefighters. Using IPA, the top pathways with more than 5 gene members annotated from differentially methylated probes included Sirtuin signaling pathway, p53 signaling, and 5' AMP-activated protein kinase (AMPK) signaling. These DNA methylation findings suggest potential cellular mechanisms associated with increased cancer risk in firefighters.

Targeting DNA Methyltranferases in Urological Tumors

Urological cancers are a heterogeneous group of malignancies accounting for a considerable proportion of cancer-related morbidity and mortality worldwide. Aberrant epigenetic traits, especially altered DNA methylation patterns constitute a hallmark of these tumors. Nonetheless, these alterations are reversible, and several efforts have been carried out to design and test several epigenetic compounds that might reprogram tumor cell phenotype back to a normal state. Indeed, several DNMT inhibitors are currently under evaluation for therapeutic efficacy in clinical trials. This review highlights the critical role of DNA methylation in urological cancers and summarizes the available data on pre-clinical assays and clinical trials with DNMT inhibitors in bladder, kidney, prostate, and testicular germ cell cancers.

Inhibition of DNMT suppresses the stemness of colorectal cancer cells through down-regulating Wnt signaling pathway

Cancer stem cell (CSC) theory reveals a new insight into the understanding of tumorigenesis and metastasis. Recently, DNA methylation is suggested to be a potential epigenetic mechanism for maintenance of CSCs. What's more, studies have shown that DNA methyltransferase (DNMT) is essential for CSCs and deletion of DNMT can reduce tumorigenesis by limiting CSC pool. Therefore, targeting the epigenetic modifiers especially DNA methylation offers an optional strategy for treating human cancers. In the present study we found that DNMT inhibitor 5-Aza-2'-deoxycytidine (5-AzaDC) markedly reduced colorectal CSC abundance in vitro and suppressed liver metastatic tumor growth in vivo. And 5-AzaDC inhibited the expression of active β-catenin and down-regulated the Wnt signaling pathway. The Wnt inhibitors were frequently inactivated by promoter methylation in colorectal cancer; however analysis of TCGA data base showed that only the expression of SFRP1 was significantly reduced in tumors compared to normal tissues. In addition, restoring of SFRP1 expression inhibited the stem cell-like potential of colorectal cancer cells. Our results indicated that inhibition of DNMT blocked the self-renewal of colorectal CSCs and SFRP1 was essential for the maintenance of colorectal CSCs.

DNMT1 ablation suppresses tumorigenesis by inhibiting the self-renewal of esophageal cancer stem cells

Cancer stem cells (CSCs) have been isolated from many tumors and considered as the main reason of cancer recurrence and metastasis. DNA methyltransferase 1 (DNMT1) mediates DNA methylation and plays an important role in CSCs maintenance. However, the function of DNMT1 in CSCs of esophageal squamous cell carcinoma (ESCC) remains unclear. In this study, we examined the role of DNMT1 in regulating self-renewal in CSCs of ESCC. We found a high expression of DNMT1 in both side population (SP) cells and sphere formation cells that represented as substitutes for CSCs in KYSE150 and EC109 ESCC cell lines. We performed the knockdown of DNMT1 using lentivirus-mediated RNA interference (RNAi) methods. We revealed that ablation of DNMT1 resulted in the numbers and self-renewal abilities of CSCs refrained significantly in ESCC cells. As a result of the CSCs inhibition, the malignant phenotypes such as cell proliferation, colony formation, migration and drug resistance abilities were dramatically inhibited in ESCC cells. Treatment of 5-aza-2'-deoxycytidine (5-aza-dC), a DNMT inhibitor, also resulted in the inhibition of CSCs and malignant profiles in ESCC cells. Our findings also provided the first evidence that 5-aza-dC inhibited the colony and sphere formation of CSCs. Thus, our results indicated that DNMT1 was important for the self-renewal maintenance of CSCs in ESCC, and 5-aza-dC could be a potential therapy for the CSCs of ESCC.

NRIP/DCAF6 stabilizes the androgen receptor protein by displacing DDB2 from the CUL4A-DDB1 E3 ligase complex in prostate cancer

Both nuclear receptor interaction protein (NRIP) and DNA damage binding protein 2 (DDB2) belong to the Cullin 4 (CUL4)-DDB1 binding protein family and are androgen receptor (AR)-interacting proteins. Here, we investigated the expression patterns of the NRIP, DDB2 and AR proteins in human prostate cancer tissues and found that the expression levels of NRIP and AR were higher, but the DDB2 level was lower, in prostate cancer tissues than in non-neoplastic controls, suggesting NRIP as a candidate tumor promoter and DDB2 as a tumor suppressor in prostate cancer. Furthermore, both NRIP and DDB2 shared the same AR binding domain; they were competitors for the AR, but not for DDB1 binding, in the AR-DDB2-DDB1-CUL4A complex. Conclusively, NRIP stabilizes the AR protein by displacing DDB2 from the AR-DDB2 complex. Consistent with our hypothesis, a specific expression pattern with high levels of NRIP and AR, together with a low level of DDB2, was found more frequently in the human prostate cancer tissues with a cribriform pattern than in non-cribriform tumors, suggesting that disruption of the balance between NRIP and DDB2 may change AR protein homeostasis and contribute to pathogenesis in certain aggressive types of prostate cancer.

Epigenetic Modifications and Head and Neck Cancer: Implications for Tumor Progression and Resistance to Therapy

Head and neck squamous carcinoma (HNSCC) is the sixth most prevalent cancer and one of the most aggressive malignancies worldwide. Despite continuous efforts to identify molecular markers for early detection, and to develop efficient treatments, the overall survival and prognosis of HNSCC patients remain poor. Accumulated scientific evidences suggest that epigenetic alterations, including DNA methylation, histone covalent modifications, chromatin remodeling and non-coding RNAs, are frequently involved in oral carcinogenesis, tumor progression, and resistance to therapy. Epigenetic alterations occur in an unsystematic manner or as part of the aberrant transcriptional machinery, which promotes selective advantage to the tumor cells. Epigenetic modifications also contribute to cellular plasticity during tumor progression and to the formation of cancer stem cells (CSCs), a small subset of tumor cells with self-renewal ability. CSCs are involved in the development of intrinsic or acquired therapy resistance, and tumor recurrences or relapse. Therefore, the understanding and characterization of epigenetic modifications associated with head and neck carcinogenesis, and the prospective identification of epigenetic markers associated with CSCs, hold the promise for novel therapeutic strategies to fight tumors. In this review, we focus on the current knowledge on epigenetic modifications observed in HNSCC and emerging Epi-drugs capable of sensitizing HNSCC to therapy.

Dissecting the roles of the androgen receptor in prostate cancer from molecular perspectives

Androgen receptor plays a pivotal role in prostate cancer progression, and androgen deprivation therapy to intercept androgen receptor signal pathway is an indispensable treatment for most advanced prostate cancer patients to delay cancer progression. However, the emerging of castration-resistant prostate cancer reminds us the alteration of androgen receptor, which includes androgen receptor mutation, the formation of androgen receptor variants, and androgen receptor distribution in cancer cells. In this review, we introduce the process of androgen receptor and also its variants' formation, translocation, and function alteration by protein modification or interaction with other pathways. We dissect the roles of androgen receptor in prostate cancer from molecular perspective to provide clues for battling prostate cancer, especially castration-resistant prostate cancer.

Epigenetics in cancer stem cells

Compelling evidence have demonstrated that bulk tumors can arise from a unique subset of cells commonly termed "cancer stem cells" that has been proposed to be a strong driving force of tumorigenesis and a key mechanism of therapeutic resistance. Recent advances in epigenomics have illuminated key mechanisms by which epigenetic regulation contribute to cancer progression. In this review, we present a discussion of how deregulation of various epigenetic pathways can contribute to cancer initiation and tumorigenesis, particularly with respect to maintenance and survival of cancer stem cells. This information, together with several promising clinical and preclinical trials of epigenetic modulating drugs, offer new possibilities for targeting cancer stem cells as well as improving cancer therapy overall.

Kaiso, a transcriptional repressor, promotes cell migration and invasion of prostate cancer cells through regulation of miR-31 expression

Kaiso, a member of the BTB/POZ zinc finger protein family, functions as a transcriptional repressor by binding to sequence-specific Kaiso binding sites or to methyl-CpG dinucleotides. Previously, we demonstrated that Kaiso overexpression and nuclear localization correlated with the progression of prostate cancer (PCa). Therefore, our objective was to explore the molecular mechanisms underlying Kaiso-mediated PCa progression. Comparative analysis of miRNA arrays revealed that 13 miRNAs were significantly altered (> 1.5 fold, p < 0.05) in sh-Kaiso PC-3 compared to sh-Scr control cells. Real-time PCR validated that three miRNAs (9, 31, 636) were increased in sh-Kaiso cells similar to cells treated with 5-aza-2′-deoxycytidine. miR-31 expression negatively correlated with Kaiso expression and with methylation of the miR-31 promoter in a panel of PCa cell lines. ChIP assays revealed that Kaiso binds directly to the miR-31 promoter in a methylation-dependent manner. Over-expression of miR-31 decreased cell proliferation, migration and invasiveness of PC-3 cells, whereas cells transfected with anti-miR-31 restored proliferation, migration and invasiveness of sh-Kaiso PC-3 cells. In PCa patients, Kaiso high/miR-31 low expression correlated with worse overall survival relative to each marker individually. In conclusion, these results demonstrate that Kaiso promotes cell migration and invasiveness through regulation of miR-31 expression.

The Efflux Transporter ABCG2 Maintains Prostate Stem Cells

Prostate stem cells (PSC) are characterized by their intrinsic resistance to androgen deprivation therapy (ADT), possibly due to the lack of androgen receptor (AR) expression. PSCs resistance to ADT and PSC expansion in castration resistant prostate cancer (CRPC) has sparked great interest in using differentiation therapy as an adjuvant to ADT. Understanding the mechanisms, by which PSCs maintain their undifferentiated phenotype, thus has important implications in differentiation therapy. In the prostate, the ATP binding cassette sub-family G member 2 (ABCG2) transporters, which enrich for AR-positive, ADT-resistant PSCs, play an important role in regulating the intracellular androgen levels by effluxing androgens. We hypothesized that the ABCG2-mediated androgen efflux is responsible for maintaining PSCs in an undifferentiated state. Using the HPr-1-AR (nontumorigenic) and CWR-R1 (tumorigenic) prostate cell lines, it was demonstrated that inhibiting the ABCG2-mediated androgen efflux, with Ko143 (ABCG2 inhibitor), increased the nuclear AR expression due to elevated intracellular androgen levels. Increased nuclear translocation of AR is followed by increased expression of AR regulated genes, a delayed cell growth response, and increased luminal differentiation. Furthermore, Ko143 reduced tumor growth rates in mice implanted with ABCG2-expressing CWR-R1 cells. In addition, Ko143-treated mice had more differentiated tumors as evidenced by an increased percentage of CK8⁺/AR⁺ luminal cells and decreased percentage of ABCG2-expressing cells. Thus, inhibiting ABCG2-mediated androgen efflux forces the PSCs to undergo an AR-modulated differentiation to an ADT-sensitive luminal phenotype.

IMPLICATIONS

This study identifies the mechanism by which the prostate stem cell marker, ABCG2, plays a role in prostate stem cell maintenance and provides a rationale for targeting ABCG2 for differentiation therapy in prostate cancer. Mol Cancer Res; 15(2); 128-40. ©2016 AACR.

Epigenetic modulators as therapeutic targets in prostate cancer

Prostate cancer is one of the most common non-cutaneous malignancies among men worldwide. Epigenetic aberrations, including changes in DNA methylation patterns and/or histone modifications, are key drivers of prostate carcinogenesis. These epigenetic defects might be due to deregulated function and/or expression of the epigenetic machinery, affecting the expression of several important genes. Remarkably, epigenetic modifications are reversible and numerous compounds that target the epigenetic enzymes and regulatory proteins were reported to be effective in cancer growth control. In fact, some of these drugs are already being tested in clinical trials. This review discusses the most important epigenetic alterations in prostate cancer, highlighting the role of epigenetic modulating compounds in pre-clinical and clinical trials as potential therapeutic agents for prostate cancer management.

Regulation of miR-200c and miR-141 by Methylation in Prostate Cancer

BACKGROUND

In prostate cancer (PCa), abnormal expression of several microRNAs (miRNAs) has been previously reported. Increasing evidence shows that aberrant epigenetic regulation of miRNAs is a contributing factor to their altered expression in cancer. In this study, we investigate whether expression of miR-200c and miR-141 in PCa is related to the DNA methylation status of their promoter.

METHODS

PCR analysis of miR-200c and miR-141, and CpG methylation analysis of their common promoter, was performed in PCa cell-lines and in archived prostate biopsy specimens. The biological significance of miR-200c and miR-141 expression in prostate cancer cells was assessed by a series of in vitro bioassays and the effect on proposed targets DNMT3A and TET1/TET3 was investigated. The effect on promoter methylation status in cells treated with demethylating agents was also examined.

RESULTS

miR-200c and miR-141 are both highly elevated in LNCaP, 22RV1, and DU145 cells, but significantly reduced in PC3 cells. This correlates inversely with the methylation status of the miR-200c/miR-141 promoter, which is unmethylated in LNCaP, 22RV1, and DU145 cells, but hypermethylated in PC3. In PC3 cells, miR-200c and miR-141 expression is subsequently elevated by treatment with the demethylating drug decitabine (5-aza-2'deoxycytidine) and by knockdown of DNA methyltransferase 1 (DNMT1), suggesting their expression is regulated by methylation. Expression of miR-200c and miR-141 in prostate biopsy tissue was inversely correlated with methylation in promoter CpG sites closest to the miR-200c/miR-141 loci. In vitro, over-expression of miR-200c in PC3 cells inhibited growth and clonogenic potential, as well as inducing apoptosis. Expression of the genes DNMT3A and TET1/TET3 were down-regulated by miR-200c and miR-141 respectively. Finally, treatment with the soy isoflavone genistein caused demethylation of the promoter CpG sites closest to the miR-200c/miR-141 loci resulting in increased miR-200c expression.

CONCLUSIONS

Our findings provide evidence that miR-200c and miR-141 are under epigenetic regulation in PCa cells. We propose that profiling their expression and methylation status may have potential as a novel biomarker or focus of therapeutic intervention in the diagnosis and prognosis of PCa. Prostate 76:1146-1159, 2016. © 2016 Wiley Periodicals, Inc.

Infiltrating mast cells enhance prostate cancer invasion via altering LncRNA-HOTAIR/PRC2-androgen receptor (AR)-MMP9 signals and increased stem/progenitor cell population

Early studies indicated that selective inflammatory immune cells in the prostate tumor microenvironment might be able to influence prostate cancer (PCa) progression. Here we found treating PCa cells with androgen deprivation therapy (ADT) results in the recruitment of more mast cells, which might then increase PCa cell invasion via down-regulation of AR signals in 4 different PCa cell lines. Mechanism dissection revealed infiltrating mast cells could decrease AR transcription via modulation of the PRC2 complex with LncRNA-HOTAIR at the AR 5' promoter region in PCa cells. The consequences of suppressing AR may then increase PCa cell invasion via increased MMP9 expression and/or increased stem/progenitor cell population. The in vivo mouse model with orthotopically xenografted PCa CWR22Rv1 cells with/without mast cells also confirmed that infiltrating mast cells could increase PCa cell invasion via suppression of AR signals. Together, our results provide a new mechanism for the ADT-enhanced PCa metastasis via altering the infiltrating mast cells to modulate PCa AR-MMP9 signals and/or AR-stem/progenitor cell population. Targeting these newly identified inflammatory mast cells-AR signals may help us to better suppress PCa metastasis at the castration resistant stage.

Two-hit exposure to polychlorinated biphenyls at gestational and juvenile life stages: 2. Sex-specific neuromolecular effects in the brain

Exposures to polychlorinated biphenyls (PCBs) during early development have long-lasting, sexually dimorphic consequences on adult brain and behavior. However, few studies have investigated their effects during juvenile development, a time when increases in pubertal hormones influence brain maturation. Here, male and female Sprague Dawley rats were exposed to PCBs (Aroclor 1221, 1 mg/kg/day) or vehicle prenatally, during juvenile development, or both, and their effects on serum hormone concentrations, gene expression, and DNA methylation were assessed in adulthood. Gene expression in male but not female brains was affected by 2-hits of PCBs, a result that paralleled behavioral effects of PCBs. Furthermore, the second hit often changed the effects of a first hit in complex ways. Thus, PCB exposures during critical fetal and juvenile developmental periods result in unique neuromolecular phenotypes, with males most vulnerable to the treatments.

Concise review: androgen receptor differential roles in stem/progenitor cells including prostate, embryonic, stromal, and hematopoietic lineages

Stem/progenitor (S/P) cells are special types of cells that have the ability to generate tissues throughout their entire lifetime and play key roles in the developmental process. Androgen and the androgen receptor (AR) signals are the critical determinants in male gender development, suggesting that androgen and AR signals might modulate the behavior of S/P cells. In this review, we summarize the AR effects on the behavior of S/P cells, including self-renewal, proliferation, apoptosis, and differentiation in normal S/P cells, as well as proliferation, invasion, and self-renewal in prostate cancer S/P cells. AR plays a protective role in the oxidative stress-induced apoptosis in embryonic stem cells. AR inhibits the self-renewal of embryonic stem cells, bone marrow stromal cells, and prostate S/P cells, but promotes their differentiation except for adipogenesis. However, AR promotes the proliferation of hematopoietic S/P cells and stimulates hematopoietic lineage differentiation. In prostate cancer S/P cells, AR suppresses their self-renewal, metastasis, and invasion. Together, AR differentially influences the characteristics of normal S/P cells and prostate cancer S/P cells, and targeting AR might improve S/P cell transplantation therapy, especially in embryonic stem cells and bone marrow stromal cells.

Gene methylation of human ovarian carcinoma stromal progenitor cells promotes tumorigenesis

Background

This study aimed to investigate whether the DNA methylation of human ovarian carcinoma stromal progenitor cells (OCSPCs) could promote the tumorigenesis of ovarian carcinoma.

Methods

OCSPCs were first isolated from fresh tumor tissues and ascites of ovarian cancer patients. In vivo and in vitro experiments on the effect of the OCSPCs on tumorigenesis and the effects of DNA demethylation on the OCSPCs were then performed.

Results

The OCSPCs possessed self-renewal and multipotent differentiation capacity with elevated expressions of OCT4, NANOG, BMP2, BMP4, Rex-1, AC133 and TGF-β. The OCSPCs, when combined with tumor cells in vivo could promote tumor growth. The methylation profiles of tumor suppressor genes (TSGs) were significantly higher in the OCSPCs than in ovarian cancer cells (p < 0.001). 5-aza-2-dC could alter the methylation levels of TSGs in OCSPCs and also inhibit the tumor promoting capabilities of the OCSPCs by decreasing the proliferation of tumors cells. The expression levels of TSGs were re-expressed by 5-aza-2-dC to inhibit the self-renewal and growth of OCSPCs.

Conclusions

OCSPCs with decreased TSG expressions in the ovarian tumor microenvironment were able to promote tumorigenesis which could be reversed by DNA demethylation. DNA demethylation reversing the expression of TSGs in OCSPCs may represent a potential therapeutic target for ovarian cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0722-7) contains supplementary material, which is available to authorized users.

Epigenetic changes in gastroenteropancreatic neuroendocrine tumours

An understanding of epigenetic drivers of tumorigenesis has developed rapidly during the last years. The identification of these changes including DNA methylation and histone modifications in gastroenteropancreatic neuroendocrine tumours (GEP-NETs) is a step forward in trying to define underlying biologic processes in this heterogeneous disease. The reversible nature of these changes represents a potential therapeutic target. We present an overview of the current knowledge of epigenetic alterations related to GEP-NETs, focusing on the influence and impact these changes have on pathogenesis and prognosis. The potential role of demethylating agents in the management of this patient population is discussed.

The androgen receptor plays a suppressive role in epithelial- mesenchymal transition of human prostate cancer stem progenitor cells

BACKGROUND

To investigate the roles of androgen receptor (AR) in epithelial- mesenchymal transition (EMT) in human prostate cancer stem progenitor (S/P) cells isolated from LNCaP cell line.

METHODS

The S/P cells were obtained from LNCaP cell line through florescence-activated cell sorting (FACS). AR was overexpressed in S/P cells through lentivirus. Western blot assay was used to detect the EMT markers expression, such as E Cadherin, N Cadherin, Vimentin and Snail. MTT assay, soft agar colony formation assay, sphere formation assay and migration assay were used to investigate AR's roles in EMT of S/P cells. Cell signaling pathways associated with proliferation and apoptosis of S/P cells were detected simultaneously. And S/P cells were treated with in vitro combinatory use of LY 294002 (inhibitor of AKT signaling molecules) with γ-TT and/or 5-AZA.

RESULTS

Our data showed that S/P cells from LNCaP had high EMT markers expression, more tumorigenesis and strong migration ability. And in S/P cells overexpressed with AR, the expression of EMT markers decreased. In addition, these cells had less proliferation ability, tumorigenesis ability, self-renewal and migration ability. At the same time, targeting S/P cells with AKT signaling pathway inhibitor LY29004 and γ-TT and/or 5-AZA could inhibit S/P cell's proliferation and tumorigenesis.

CONCLUSIONS

Our data suggest that AR played a negative role in EMT of PCa S/P cells, by regulating AKT cell signaling pathway, which could be a new strategy to treat castration resistant prostate cancer (CRPC).

Epigenetic regulation of Elf5 is associated with epithelial-mesenchymal transition in urothelial cancer

E74-like factor 5 (Elf5) has been associated with tumor suppression in breast cancer. However, its role in urothelial cancer (UC) is completely unknown. Immunohistochemistry (IHC) and methylation specific PCR (MSP) were done to detect Elf5 expression level and its promoter methylation. Results revealed that low expression of Elf5 on protein and mRNA levels were associated with tumor progression, early relapse and poor survival. In vitro, down-regulation of Elf5 can increase epithelial-mesenchymal transition (EMT). Aberrant Elf5 methylation was identified as major mechanism for Elf5 gene silence. Accordingly, restoration of Elf5 by infection or demethylating treatment effectively reversed EMT processes. In conclusion, we identified Elf5 as a novel biomarker of UC on several biological levels and established a causative link between Elf5 and EMT in UC.

Epigenetic therapy of cancer stem and progenitor cells by targeting DNA methylation machineries

Recent advances in stem cell biology have shed light on how normal stem and progenitor cells can evolve to acquire malignant characteristics during tumorigenesis. The cancer counterparts of normal stem and progenitor cells might be occurred through alterations of stem cell fates including an increase in self-renewal capability and a decrease in differentiation and/or apoptosis. This oncogenic evolution of cancer stem and progenitor cells, which often associates with aggressive phenotypes of the tumorigenic cells, is controlled in part by dysregulated epigenetic mechanisms including aberrant DNA methylation leading to abnormal epigenetic memory. Epigenetic therapy by targeting DNA methyltransferases (DNMT) 1, DNMT3A and DNMT3B via 5-Azacytidine (Aza) and 5-Aza-2’-deoxycytidine (Aza-dC) has proved to be successful toward treatment of hematologic neoplasms especially for patients with myelodysplastic syndrome. In this review, I summarize the current knowledge of mechanisms underlying the inhibition of DNA methylation by Aza and Aza-dC, and of their apoptotic- and differentiation-inducing effects on cancer stem and progenitor cells in leukemia, medulloblastoma, glioblastoma, neuroblastoma, prostate cancer, pancreatic cancer and testicular germ cell tumors. Since cancer stem and progenitor cells are implicated in cancer aggressiveness such as tumor formation, progression, metastasis and recurrence, I propose that effective therapeutic strategies might be achieved through eradication of cancer stem and progenitor cells by targeting the DNA methylation machineries to interfere their “malignant memory”.

Epigenetics in breast and prostate cancer

Most recent investigations into cancer etiology have identified a key role played by epigenetics. Specifically, aberrant DNA and histone modifications which silence tumor suppressor genes or promote oncogenes have been demonstrated in multiple cancer models. While the role of epigenetics in several solid tumor cancers such as colorectal cancer are well established, there is emerging evidence that epigenetics also plays a critical role in breast and prostate cancer. In breast cancer, DNA methylation profiles have been linked to hormone receptor status and tumor progression. Similarly in prostate cancer, epigenetic patterns have been associated with androgen receptor status and response to therapy. The regulation of key receptor pathways and activities which affect clinical therapy treatment options by epigenetics renders this field high priority for elucidating mechanisms and potential targets. A new set of methylation arrays are now available to screen epigenetic changes and provide the cutting-edge tools needed to perform such investigations. The role of nutritional interventions affecting epigenetic changes particularly holds promise. Ultimately, determining the causes and outcomes from epigenetic changes will inform translational applications for utilization as biomarkers for risk and prognosis as well as candidates for therapy.

Androgen receptor DNA methylation regulates the timing and androgen sensitivity of mouse prostate ductal development

Androgen receptor (AR) signaling initiates mouse prostate development by stimulating prostate ductal bud formation and specifying bud patterns. Curiously, however, prostatic bud initiation lags behind the onset of gonadal testosterone synthesis by about three days. This study's objective was to test the hypothesis that DNA methylation controls the timing and scope of prostate ductal development by regulating Ar expression in the urogenital sinus (UGS) from which the prostate derives. We determined that Ar DNA methylation decreases in UGS mesenchyme during prostate bud formation in vivo and that this change correlates with decreased DNA methyltransferase expression in the same cell population during the same time period. To examine the role of DNA methylation in prostate development, fetal UGSs were grown in serum-free medium and 5 alpha dihydrotestosterone (DHT) and the DNA methylation inhibitor 5'-aza-2'-deoxycytidine (5AzadC) were introduced into the medium at specific times. As a measure of prostate development, in situ hybridization was used to visualize and count Nkx3-1 mRNA positive prostatic buds. We determined that inhibiting DNA methylation when prostatic buds are being specified, accelerates the onset of prostatic bud development, increases bud number, and sensitizes the budding response to androgens. Inhibition of DNA methylation also reduces Ar DNA methylation in UGS explants and increases Ar mRNA and protein in UGS mesenchyme and epithelium. Together, these results support a novel mechanism whereby Ar DNA methylation regulates UGS androgen sensitivity to control the rate and number of prostatic buds formed, thereby establishing a developmental checkpoint.

Novel epigenetic target therapy for prostate cancer: a preclinical study

Epigenetic events are critical contributors to the pathogenesis of cancer, and targeting epigenetic mechanisms represents a novel strategy in anticancer therapy. Classic demethylating agents, such as 5-Aza-2′-deoxycytidine (Decitabine), hold the potential for reprograming somatic cancer cells demonstrating high therapeutic efficacy in haematological malignancies. On the other hand, epigenetic treatment of solid tumours often gives rise to undesired cytotoxic side effects. Appropriate delivery systems able to enrich Decitabine at the site of action and improve its bioavailability would reduce the incidence of toxicity on healthy tissues. In this work we provide preclinical evidences of a safe, versatile and efficient targeted epigenetic therapy to treat hormone sensitive (LNCap) and hormone refractory (DU145) prostate cancers. A novel Decitabine formulation, based on the use of engineered erythrocyte (Erythro-Magneto-Hemagglutinin Virosomes, EMHVs) drug delivery system (DDS) carrying this drug, has been refined. Inside the EMHVs, the drug was shielded from the environment and phosphorylated in its active form. The novel magnetic EMHV DDS, endowed with fusogenic protein, improved the stability of the carried drug and exhibited a high efficiency in confining its delivery at the site of action in vivo by applying an external static magnetic field. Here we show that Decitabine loaded into EMHVs induces a significant tumour mass reduction in prostate cancer xenograft models at a concentration, which is seven hundred times lower than the therapeutic dose, suggesting an improved pharmacokinetics/pharmacodynamics of drug. These results are relevant for and discussed in light of developing personalised autologous therapies and innovative clinical approach for the treatment of solid tumours.

The Multifaceted Roles of STAT3 Signaling in the Progression of Prostate Cancer

The signal transducer and activator of transcription (STAT)3 governs essential functions of epithelial and hematopoietic cells that are often dysregulated in cancer. While the role for STAT3 in promoting the progression of many solid and hematopoietic malignancies is well established, this review will focus on the importance of STAT3 in prostate cancer progression to the incurable metastatic castration-resistant prostate cancer (mCRPC). Indeed, STAT3 integrates different signaling pathways involved in the reactivation of androgen receptor pathway, stem like cells and the epithelial to mesenchymal transition that drive progression to mCRPC. As equally important, STAT3 regulates interactions between tumor cells and the microenvironment as well as immune cell activation. This makes it a major factor in facilitating prostate cancer escape from detection of the immune response, promoting an immunosuppressive environment that allows growth and metastasis. Based on the multifaceted nature of STAT3 signaling in the progression to mCRPC, the promise of STAT3 as a therapeutic target to prevent prostate cancer progression and the variety of STAT3 inhibitors used in cancer therapies is discussed.

Quality of Life and Sexual Health in the Aging of PCa Survivors

Prostate cancer (PCa) is the most common malignancy in elderly men. The progressive ageing of the world male population will further increase the need for tailored assessment and treatment of PCa patients. The determinant role of androgens and sexual hormones for PCa growth and progression has been established. However, several trials on androgens and PCa are recently focused on urinary continence, quality of life, and sexual function, suggesting a new point of view on the whole endocrinological aspect of PCa. During aging, metabolic syndrome, including diabetes, hypertension, dyslipidemia, and central obesity, can be associated with a chronic, low-grade inflammation of the prostate and with changes in the sex steroid pathways. These factors may affect both the carcinogenesis processes and treatment outcomes of PCa. Any treatment for PCa can have a long-lasting negative impact on quality of life and sexual health, which should be assessed by validated self-reported questionnaires. In particular, sexual health, urinary continence, and bowel function can be worsened after prostatectomy, radiotherapy, or hormone treatment, mostly in the elderly population. In the present review we summarized the current knowledge on the role of hormones, metabolic features, and primary treatments for PCa on the quality of life and sexual health of elderly Pca survivors.

Contributions of epithelial-mesenchymal transition and cancer stem cells to the development of castration resistance of prostate cancer

An important clinical challenge in prostate cancer therapy is the inevitable transition from androgen-sensitive to castration-resistant and metastatic prostate cancer. Albeit the androgen receptor (AR) signaling axis has been targeted, the biological mechanism underlying the lethal event of androgen independence remains unclear. New emerging evidences indicate that epithelial-to-mesenchymal transition (EMT) and cancer stem cells (CSCs) play crucial roles during the development of castration-resistance and metastasis of prostate cancer. Notably, EMT may be a dynamic process. Castration can induce EMT that may enhance the stemness of CSCs, which in turn results in castration-resistance and metastasis. Reverse of EMT may attenuate the stemness of CSCs and inhibit castration-resistance and metastasis. These prospective approaches suggest that therapies target EMT and CSCs may cast a new light on the treatment of castration-resistant prostate cancer (CRPC) in the future. Here we review recent progress of EMT and CSCs in CRPC.

Androgen receptor (AR) differential roles in hormone-related tumors including prostate, bladder, kidney, lung, breast and liver

The androgen receptor (AR) is expressed in many cell types and the androgen/AR signaling has been found to have important roles in modulating tumorigenesis and metastasis in several cancers including prostate, bladder, kidney, lung, breast and liver. However, whether AR has differential roles in the individual cells within these tumors that contain a variety of cell types remains unclear. Generation of AR knockout (ARKO) mouse models with deletion of AR in selective cells within tumors indeed have uncovered many unique AR roles in the individual cell types during cancer development and progression. This review will discuss the results obtained from various ARKO mice and different human cell lines with special attention to the cell type- and tissue-specific ARKO models. The understanding of various results showing the AR indeed has distinct and contrasting roles in each cell type within many hormone-related tumors (as stimulator in bladder, kidney and lung metastases vs as suppressor in prostate and liver metastases) may eventually help us to develop better therapeutic approaches by targeting the AR or its downstream signaling in individual cell types to better battle these hormone-related tumors in different stages.

Prostate cancer research in China

Prostate cancer (PCa) research in China has been on a rocketing trend in recent years. The first genome-wide association study (GWAS) in China identified two new PCa risk associated single nucleotide polymorphisms (SNPs). Next generation sequencing is beginning to be used, yielding novel findings: gene fusions, long non-coding RNAs and other variations. Mechanisms of PCa progression have been illustrated while various diagnosis biomarkers have been investigated extensively. Personalized therapy based on genetic factors, nano-medicine and traditional Chinese medicine has been the focus of experimental therapeutic research for PCa. This review intends to shed light upon the recent progress in PCa research in China and points out the possible breakthroughs in the future.