Role of non-genomic androgen signalling in suppressing proliferation of fibroblasts and fibrosarcoma cells

Filamin A in triple negative breast cancer

Triple-negative breast cancer is a rare but highly heterogeneous breast cancer subtype with a limited choice of specific treatments. Chemotherapy remains the only efficient treatment, but its side effects and the development of resistance consolidate the urgent need to discover new targets. In TNBC, filamin A expression correlates to grade and TNM stage. Accordingly, this protein could constitute a new target for this BC subtype. Even if most of the data indicates its direct involvement in cancer progression, some contrasting results underline the need to deepen the studies. To elucidate a possible function of this protein as a TNBC marker, we summarized the main characteristic of filamin A and its involvement in physiological and pathological processes such as cancer. Lastly, we scrutinized its actions in triple-negative breast cancer and highlighted the need to increase the number of studies useful to better clarify the role of this versatile protein as a marker and target in TNBC, alone or in "collaboration" with other proteins with a relevant role in this BC subgroup.

Filamin A cooperates with the androgen receptor in preventing skeletal muscle senescence

Aging induces a slow and progressive decrease in muscle mass and function, causing sarcopenia. Androgens control muscle trophism and exert important anabolic functions through the binding to the androgen receptor. Therefore, analysis of the androgen receptor-mediated actions in skeletal muscle might provide new hints for a better understanding of sarcopenia pathogenesis. In this study, we report that expression of the androgen receptor in skeletal muscle biopsies from 20 subjects is higher in young, as compared with old subjects. Co-immunoprecipitation experiments reveal that the androgen receptor is complexed with filamin A mainly in young, that in old subjects. Therefore, we have in depth analyzed the role of such complex using C2C12 myoblasts that express a significant amount of the androgen receptor. In these cells, hormone stimulation rapidly triggers the assembly of the androgen receptor/filamin A complex. Such complex prevents the senescence induced by oxidative stress in C2C12 cells, as disruption of the androgen receptor/filamin A complex by Rh-2025u stapled peptide re-establishes the senescent phenotype in C2C12 cells. Simultaneously, androgen stimulation of C2C12 cells rapidly triggers the activation of various signaling effectors, including Rac1, focal adhesion kinase, and mitogen-activated kinases. Androgen receptor blockade by bicalutamide or perturbation of androgen receptor/filamin A complex by Rh-2025u stapled peptide both reverse the hormone activation of signaling effectors. These findings further reinforce the role of the androgen receptor and its extranuclear partners in the rapid hormone signaling that controls the functions of C2C12 cells. Further investigations are needed to promote clinical interventions that might ameliorate muscle cell function as well the clinical outcome of age-related frailty.

Recent trends in diabetic wound healing with nanofibrous scaffolds

There is an emphasis in this review on nanofibrous scaffolds (NFSs) in diabetic wound healing, as well as their mechanisms and recent advancements. Diabetes-related complex wounds pose an important problem to humanity, due to the fact that their chronic nature can lead to serious complications including sepsis and amputations. Despite the fact that there are certain therapy options available for diabetic wound healing, these options are either ineffective or intrusive, making clinical intervention difficult. Clinical research is also challenged by the emergence of bacterial resistance to standard antibiotics. However, research into nanotechnology, in particular NFSs, is growing swiftly and has a positive impact on the treatment of diabetic wounds. For instance, SpinCare™, developed by Nanomedic Technologies Ltd, has successfully finished clinical testing and can re-epithelialize second-degree burns and chronic diabetic wounds in 7 and 14 days, respectively. In this review, we discussed homologous studies as well as other recent research studies on diabetic wound healing using NFSs.

Cancer-Associated Fibroblast: Role in Prostate Cancer Progression to Metastatic Disease and Therapeutic Resistance

Prostate cancer (PCa) is one of the most common cancers in European males. Although therapeutic approaches have changed in recent years, and several new drugs have been approved by the Food and Drug Administration (FDA), androgen deprivation therapy (ADT) remains the standard of care. Currently, PCa represents a clinical and economic burden due to the development of resistance to ADT, paving the way to cancer progression, metastasis, and to long-term side effects induced by ADT and radio-chemotherapeutic regimens. In light of this, a growing number of studies are focusing on the tumor microenvironment (TME) because of its role in supporting tumor growth. Cancer-associated fibroblasts (CAFs) have a central function in the TME because they communicate with prostate cancer cells, altering their metabolism and sensitivity to drugs; hence, targeted therapy against the TME, and, in particular, CAFs, could represent an alternative therapeutic approach to defeat therapy resistance in PCa. In this review, we focus on different CAF origins, subsets, and functions to highlight their potential in future therapeutic strategies for prostate cancer.

Androgens and NGF Mediate the Neurite-Outgrowth through Inactivation of RhoA

Steroid hormones and growth factors control neuritogenesis through their cognate receptors under physiological and pathological conditions. We have already shown that nerve growth factor and androgens induce neurite outgrowth of PC12 cells through a reciprocal crosstalk between the NGF receptor, TrkA and the androgen receptor. Here, we report that androgens or NGF induce neuritogenesis in PC12 cells through inactivation of RhoA. Ectopic expression of the dominant negative RhoA N19 promotes, indeed, the neurite-elongation of unchallenged and androgen- or NGF-challenged PC12 cells and the increase in the expression levels of βIII tubulin, a specific neuronal marker. Pharmacological inhibition of the Ser/Thr kinase ROCK, an RhoA effector, induces neuritogenesis in unchallenged PC12 cells, and potentiates the effect of androgens and NGF, confirming the role of RhoA/ROCK axis in the neuritogenesis induced by androgen and NGF, through the phosphorylation of Akt. These findings suggest that therapies based on new selective androgen receptor modulators and/or RhoA/ROCK inhibitors might exert beneficial effects in the treatment of neuro-disorders, neurological diseases and ageing-related processes.

New Insights and Emerging Therapeutic Approaches in Prostate Cancer

Prostate cancer is the second most frequently diagnosed cancer in men and several therapeutic approaches are currently available for patient's care. Although the androgen receptor status represents a good predictor of response to androgen deprivation therapy, prostate cancer frequently becomes resistant to this approach and spreads. The molecular mechanisms that contribute to progression and drug-resistance of this cancer remain still debated. However, few therapeutic options are available for patient's management, at this stage. Recent years have seen a great expansion of the studies concerning the role of stromal-epithelial interactions and tumor microenvironment in prostate cancer progression. The findings so far collected have provided new insights into diagnostic and clinical management of prostate cancer patients. Further, new fascinating aspects concerning the intersection of the androgen receptor with survival factors as well as calcium channels have been reported in cultured prostate cancer cells and mouse models. The results of these researches have opened the way for a better understanding of the basic mechanisms involved in prostate cancer invasion and drug-resistance. They have also significantly expanded the list of new biomarkers and druggable targets in prostate cancer. The primary aim of this manuscript is to provide an update of these issues, together with their translational aspects. Exploiting the power of novel promising therapeutics would increase the success rate in the diagnostic path and clinical management of patients with advanced disease.

A Small Peptide Targeting the Ligand-Induced Androgen Receptor/Filamin a Interaction Inhibits the Invasive Phenotype of Prostate Cancer Cells

Prostate cancer (PC) is one of the most widespread malignancies among males worldwide. The androgen receptor (AR) plays a major role in prostate cancer development and progression and is the main target of PC therapy. Nonetheless, its action is not yet fully elucidated. We report here that the AR associates with Filamin A (FlnA) promoting migration and invasiveness of various PC-derived cells after androgen challenging. Inhibition of the AR/FlnA complex assembly by a very low concentration of Rh-2025u, an AR-derived peptide specifically interfering with this association, impairs such phenotype in monolayer cells and in 3D models. This study, together with our recent data in cancer-associated fibroblasts (CAFs), indicates that targeting the AR/FlnA complex could improve the clinical management of invasive PC, as the limited number of new drugs reaching the market suggests that we must re-examine the way invasive PC is currently treated. In this context, the synthesis of new biologically active molecules, such as the Rh-2025u peptide, which has been shown to efficiently interfere in the complex assembly in CAFs and PC cells, should overcome the limits of current available therapies, mostly based on hormone antagonists.

Therapeutic potential of TRPM8 antagonists in prostate cancer

Transient receptor potential melastatin-8 (TRPM8) represents an emerging target in prostate cancer, although its mechanism of action remains unclear. Here, we have characterized and investigated the effects of TRPM8 modulators in prostate cancer aggressiveness disclosing the molecular mechanism underlying their biological activity. Patch-clamp and calcium fluorometric assays were used to characterize the synthesized compounds. Androgen-stimulated prostate cancer-derived cells were challenged with the compounds and the DNA synthesis was investigated in a preliminary screening. The most effective compounds were then employed to inhibit the pro-metastatic behavior of in various PC-derived cells, at different degree of malignancy. The effect of the compounds was then assayed in prostate cancer cell-derived 3D model and the molecular targets of selected compounds were lastly identified using transcriptional and non-transcriptional reporter assays. TRPM8 antagonists inhibit the androgen-dependent prostate cancer cell proliferation, migration and invasiveness. They are highly effective in reverting the androgen-induced increase in prostate cancer cell spheroid size. The compounds also revert the proliferation of castrate-resistant prostate cancer cells, provided they express the androgen receptor. In contrast, no effects were recorded in prostate cancer cells devoid of the receptor. Selected antagonists interfere in non-genomic androgen action and abolish the androgen-induced androgen receptor/TRPM8 complex assembly as well as the increase in intracellular calcium levels in prostate cancer cells. Our results shed light in the processes controlling prostate cancer progression and make the transient receptor potential melastatin-8 as a ‘druggable’ target in the androgen receptor-expressing prostate cancers.

Non-genomic signaling of steroid receptors in cancer

Steroid receptors (SRs) are members of the nuclear receptor family, which are ligand-activated transcription factors. SRs regulate many physiological functions including development and reproduction, though they can also be involved in several pathologies, especially cancer. Highly controlled cellular responses to steroids involve transcriptional regulation (genomic activity) combined with direct activation of signaling cascades (non-genomic activity). Non-genomic signaling has been extensively studied in cancer, mainly in breast cancer for ER and PR, and prostate cancer for AR. Even though most of the studies have been conducted in cells, some of them have been confirmed in vivo, highlighting the relevance of this pathway in cancer. This review provides an overview of the current and emerging knowledge on non-genomic signaling with a focus on breast and prostate cancers and its clinical relevance. A thorough understanding of ER, PR, AR and GR non-genomic pathways may open new perspectives for the development of therapeutic strategies.

Communication between cells: exosomes as a delivery system in prostate cancer

Despite the considerable efforts in screening and diagnostic protocols, prostate cancer still represents the second leading cause of cancer-related death in men. Many patients with localized disease and low risk of recurrence have a favourable outcome. In a substantial proportion of patients, however, the disease progresses and becomes aggressive. The mechanisms that promote prostate cancer progression remain still debated. Many findings point to the role of cross-communication between prostate tumor cells and their surrounding microenvironment during the disease progression. Such a connection fosters survival, proliferation, angiogenesis, metastatic spreading and drug-resistance of prostate cancer. Recent years have seen a profound interest in understanding the way by which prostate cancer cells communicate with the surrounding cells in the microenvironment. In this regard, direct cell-to-cell contacts and soluble factors have been identified. Increasing evidence indicates that PC cells communicate with the surrounding cells through the release of extracellular vesicles, mainly the exosomes. By directly acting in stromal or prostate cancer epithelial cells, exosomes represent a critical intercellular communication system. By querying the public database ( https://pubmed.ncbi.nlm.nih.gov ) for the past 10 years, we have found more than four hundred papers. Among them, we have extrapolated the most relevant about the role of exosomes in prostate cancer malignancy and progression. Emerging data concerning the use of these vesicles in diagnostic management and therapeutic guidance of PC patients are also presented. Video Abstract.

The Role of Androgen Receptor in Cross Talk Between Stromal Cells and Prostate Cancer Epithelial Cells

Prostate cancer (PCa) lists as the second most lethal cancer for men in western countries, and androgen receptor (AR) plays a central role in its initiation and progression, which prompts the development of androgen deprivation therapy (ADT) as the standard treatment. Prostate tumor microenvironment, consisting of stromal cells and extracellular matrix (ECM), has dynamic interactions with PCa epithelial cells and affects their growth and invasiveness. Studies have shown that both genomic and non-genomic AR signaling pathways are involved in the biological regulation of PCa epithelial cells. In addition, AR signaling in prostate stroma is also involved in PCa carcinogenesis and progression. Loss of AR in PCa stroma is clinically observed as PCa progresses to advanced stage. Especially, downregulation of AR in stromal fibroblasts dysregulates the expression levels of ECM proteins, thus creating a suitable environment for PCa cells to metastasize. Importantly, ADT treatment enhances this reciprocal interaction and predisposes stromal cells to promote cell invasion of PCa cells. During this process, AR in PCa epithelium actively responds to various stimuli derived from the surrounding stromal cells and undergoes enhanced degradation while elevating the expression of certain genes such as MMP9 responsible for cell invasion. AR reduction in epithelial cells also accelerates these cells to differentiate into cancer stem-like cells and neuroendocrine cells, which are AR-negative PCa cells and inherently resistant to ADT treatments. Overall, understanding of the cross talk between tumor microenvironment and PCa at the molecular level may assist the development of novel therapeutic strategies against this disease. This review will provide a snapshot of AR's action when the interaction of stromal cells and PCa cells occurs.

Targeting the Nerve Growth Factor Signaling Impairs the Proliferative and Migratory Phenotype of Triple-Negative Breast Cancer Cells

Triple-negative breast cancer is a heterogeneous disease that still lacks specific therapeutic approaches. The identification of new biomarkers, predictive of the disease's aggressiveness and pharmacological response, is a challenge for a more tailored approach in the clinical management of patients. Nerve growth factor, initially identified as a key factor for neuronal survival and differentiation, turned out to be a multifaceted molecule with pleiotropic effects in quite divergent cell types, including cancer cells. Many solid tumors exhibit derangements of the nerve growth factor and its receptors, including the tropomyosin receptor kinase A. This receptor is expressed in triple-negative breast cancer, although its role in the pathogenesis and aggressiveness of this disease is still under investigation. We now report that triple-negative breast cancer-derived MDA-MB-231 and MDA-MB-453 cells express appreciable levels of tropomyosin receptor kinase A and release a biologically active nerve growth factor. Activation of tropomyosin receptor kinase by nerve growth factor treatment positively affects the migration, invasion, and proliferation of triple-negative breast cancer cells. An increase in the size of triple-negative breast cancer cell spheroids is also detected. This latter effect might occur through the nerve growth factor-induced release of matrix metalloproteinase 9, which contributes to the reorganization of the extracellular matrix and cell invasiveness. The tropomyosin receptor kinase A inhibitor GW441756 reverses all these responses. Co-immunoprecipitation experiments in both cell lines show that nerve growth factor triggers the assembly of the TrkA/β1-integrin/FAK/Src complex, thereby activating several downstream effectors. GW441756 prevents the complex assembly induced by nerve growth factor as well as the activation of its dependent signaling. Pharmacological inhibition of the tyrosine kinases Src and FAK (focal adhesion kinase), together with the silencing of β1-integrin, shows that the tyrosine kinases impinge on both proliferation and motility, while β1-integrin is needed for motility induced by nerve growth factor in triple-negative breast cancer cells. The present data support the key role of the nerve growth factor/tropomyosin receptor kinase A pathway in triple-negative breast cancer and offer new hints in the diagnostic and therapeutic management of patients.

The androgen receptor/filamin A complex as a target in prostate cancer microenvironment

Prostate cancer represents the major cause of cancer-related death in men and patients frequently develop drug-resistance and metastatic disease. Most studies focus on hormone-resistance mechanisms related to androgen receptor mutations or to the acquired property of prostate cancer cells to over-activate signaling pathways. Tumor microenvironment plays a critical role in prostate cancer progression. However, the mechanism involving androgen/androgen receptor signaling in cancer associated fibroblasts and consequences for prostate cancer progression still remains elusive. We now report that prostate cancer associated fibroblasts express a transcriptional-incompetent androgen receptor. Upon androgen challenging, the receptor co-localizes with the scaffold protein filamin A in the extra-nuclear compartment of fibroblasts, thus mediating their migration and invasiveness. Cancer-associated fibroblasts move towards epithelial prostate cancer cells in 2D and 3D cultures, thereby inducing an increase of the prostate cancer organoid size. Androgen enhances both these effects through androgen receptor/filamin A complex assembly in cancer-associated fibroblasts. An androgen receptor-derived stapled peptide, which disrupts the androgen receptor/filamin A complex assembly, abolishes the androgen-dependent migration and invasiveness of cancer associated fibroblasts. Notably, the peptide impairs the androgen-induced invasiveness of CAFs in 2D models and reduces the overall tumor area in androgen-treated 3D co-culture. The androgen receptor in association with β1 integrin and membrane type-matrix metalloproteinase 1 activates a protease cascade triggering extracellular matrix remodeling. The peptide also impairs the androgen activation of this cascade. This study offers a potential new marker, the androgen receptor/filamin A complex, and a new therapeutic approach targeting intracellular pathways activated by the androgen/androgen receptor axis in prostate cancer-associated fibroblasts. Such a strategy, alone or in combination with conventional therapies, may allow a more efficient treatment of prostate cancer.

Androgen Signaling in the Tumor Microenvironment

The key function of mesenchymal/stromal androgen receptor (AR) signaling for prostate development has been well documented by tissue recombination experiments. Some studies have addressed the expression and function of AR in stromal cells in prostate cancer, yet our understanding of the role of stromal AR in other tissues beyond prostate is still insufficient.Genomic analysis has revealed that cellular responses to androgens differ between epithelial and stromal cells. AR in stromal cells seems not to act via classical AR transcription factors such as FOXA1 but rather depends on the JUN/AP1 complex. Stromal AR appears to have tumor-promoting and tumor-protective functions depending on tumor stage. Loss of AR signaling in fibroblasts has been detected already in premalignant lesions in the skin and prostate and has been associated with tumor induction in xenografts of skin cancer and aggressive disease features and poor patient prognosis in prostate cancer. Moreover, AR expression is found on virtually all tissue-infiltrating immune cells and plays critical roles in immune cell function. These findings suggest a potential deleterious impact of current androgen deprivation therapies which inhibit both epithelial and stromal AR, highlighting the need to develop tissue-specific AR inhibitors.

Novel Therapeutic Strategies for CDK4/6 Inhibitors in Metastatic Castrate-Resistant Prostate Cancer

The majority of patients with castrate-resistant prostate cancer will have metastatic disease at the time of diagnosis. Investigative efforts on new therapeutics for this patient population have improved with the development of androgen signaling inhibitors, such as abiraterone and enzalutamide, and PARP inhibitors, such as rucaparib and olaparib, to accompany the previously FDA-approved docetaxel, cabazitaxel, sipuleucel-T, and Radium 223. However, new therapeutic strategies are necessary to prolong survival as progression after these agents is inevitable. CDK4/6 inhibitors have advanced the field of estrogen receptor positive breast cancer treatment and are being investigated in prostate cancer given the role of androgen receptor signaling effects on the cell cycle. Response to CDK4/6 inhibitors may be predicted by the tumors' genomic profile and may provide insight into combinatory therapy with CDK4/6 inhibitors in order to delay resistance or provide synergistic effects. Here, we review the use of CDK4/6 inhibitors in prostate cancer and potential combinations based on known resistance mechanisms to CDK4/6 inhibitors, prostate cancer regulatory pathways, and prostate-cancer-specific genomic alterations.

Mechanisms of Androgen Receptor Agonist- and Antagonist-Mediated Cellular Senescence in Prostate Cancer

The androgen receptor (AR) plays a leading role in the control of prostate cancer (PCa) growth. Interestingly, structurally different AR antagonists with distinct mechanisms of antagonism induce cell senescence, a mechanism that inhibits cell cycle progression, and thus seems to be a key cellular response for the treatment of PCa. Surprisingly, while physiological levels of androgens promote growth, supraphysiological androgen levels (SAL) inhibit PCa growth in an AR-dependent manner by inducing cell senescence in cancer cells. Thus, oppositional acting ligands, AR antagonists, and agonists are able to induce cellular senescence in PCa cells, as shown in cell culture model as well as ex vivo in patient tumor samples. This suggests a dual AR-signaling dependent on androgen levels that leads to the paradox of the rational to keep the AR constantly inactivated in order to treat PCa. These observations however opened the option to treat PCa patients with AR antagonists and/or with androgens at supraphysiological levels. The latter is currently used in clinical trials in so-called bipolar androgen therapy (BAT). Notably, cellular senescence is induced by AR antagonists or agonist in both androgen-dependent and castration-resistant PCa (CRPC). Pathway analysis suggests a crosstalk between AR and the non-receptor tyrosine kinase Src-Akt/PKB and the PI3K-mTOR-autophagy signaling in mediating AR-induced cellular senescence in PCa. In this review, we summarize the current knowledge of therapeutic induction and intracellular pathways of AR-mediated cellular senescence.

Androgen receptor activation reduces the endothelial cell proliferation through activating the cSrc/AKT/p38/ERK/NFκB-mediated pathway

The effect of androgen on angiogenesis has been documented. However, its underlying molecular mechanisms have not been well illustrated. Here, we show that treatment with an androgen receptor (AR) agonist, metribolone (R1881; 0.05-5 nM), or dihydrotestosterone (DHT; 0.5-2 nM), concentration- and time-dependently inhibited proliferation in human umbilical venous endothelial cells (HUVEC). This inhibitory effect was confirmed in human microvascular endothelial cells (HMEC-1). Flow cytometric analysis demonstrated that R1881 induced G0/G1 phase cell cycle arrest in HUVEC. Blockade of the AR activity by pre-treatment with an AR antagonist, hydroxyflutamide (HF), or knockdown of AR expression using the shRNA technique abolished the R1881-induced HUVEC proliferation inhibition, suggesting that AR activation can inhibit endothelial cell proliferation. We further investigated the signaling pathway contributing to the proliferation inhibition induced by AR activation. Our data suggest that R1881 reduced the proliferation rate of HUVEC through activating the AR/cSrc/AKT/p38/ERK/NFκB pathway, subsequently up-regulating p53 expression, which in turn increased the levels of p21 and p27 protein, hence decreasing the activities of cyclin-dependent kinase 2 (CDK2) and CDK4, and finally reduced the cell proliferation rate. An extra-nuclear pathway involved in the proliferation inhibition induced by AR activation in vascular endothelial cells was confirmed by showing that membrane-impermeable testosterone-bovine serum albumin (BSA) treatment significantly increased the levels of p53, p27 and p21 protein and reduced cell proliferation. These data highlight the underlying molecular mechanisms by which AR activation induced proliferation inhibition in vascular endothelial cells.

Non-nuclear AR Signaling in Prostate Cancer

Despite the key role played by androgen receptor (AR) in tumor cell aggressiveness and prostate cancer (PCa) progression, its function in the tumor microenvironment (TME) is still controversial. Increasing studies highlight the crucial role played by TME modulation in treatment outcome and tumor cell spreading. In this context, targeting specific constituents of the TME could be considered an alternative approach to classic treatments directed against cancer cells. Currently, androgen deprivation therapy (ADT) is a routinely adopted strategy in the management of PCa, with initial success, and consecutive fail. A possible justification to this is the fact that ADT aims to target all the transcription/translation-related activities of AR, which are typical of tumor epithelial cells. Less is still known about side effects of ADT on TME. Cancer Associated Fibroblasts (CAFs), for example, express a classic AR, mostly confined in the extra-nuclear portion of the cell. In CAFs ADT exerts a plethora of non-transcriptional effects, depending by the protein partner linked to AR, leading to cell migration, proliferation, and differentiation. In recent years, substantial progress in the structure-function relationships of AR, identification of its binding partners and function of protein complexes including AR have improved our knowledge of its signaling axis. Important AR non-genomic effects and lots of its cytoplasmatic binding partners have been described, pointing out a fine control of AR non-genomic pathways. Accordingly, new AR inhibitors have been designed and are currently under investigation. Prompt development of new approaches to target AR or block recruitment of its signaling effectors, or co-activators, is urgently needed. The present review takes an in-depth look at current literature, furnishing an exhaustive state-of-the-art overview of the non-genomic role of AR in PCa, with particular emphasis on its involvement in TME biology.

Nerve Growth Factor Induces Proliferation and Aggressiveness In Prostate Cancer Cells

Resistance to hormone therapy and disease progression is the major challenge in clinical management of prostate cancer (PC). Drugs currently used in PC therapy initially show a potent antitumor effects, but PC gradually develops resistance, relapses and spreads. Most patients who fail primary therapy and have recurrences eventually develop castration-resistant prostate cancer (CRPC), which is almost incurable. The nerve growth factor (NGF) acts on a variety of non-neuronal cells by activating the NGF tyrosine-kinase receptor, tropomyosin receptor kinase A (TrkA). NGF signaling is deregulated in PC. In androgen-dependent PC cells, TrkA mediates the proliferative action of NGF through its crosstalk with the androgen receptor (AR). Epithelial PC cells, however, acquire the ability to express NGF and TrkA, as the disease progresses, indicating a role for NGF/TrkA axis in PC progression and androgen-resistance. We here report that once activated by NGF, TrkA mediates proliferation, invasiveness and epithelial-mesenchymal transition (EMT) in various CRPC cells. NGF promotes organoid growth in 3D models of CRPC cells, and specific inhibition of TrkA impairs all these responses. Thus TrkA represents a new biomarker to target in CRPC.

Androgens Induce Invasiveness of Triple Negative Breast Cancer Cells Through AR/Src/PI3-K Complex Assembly

Breast cancer (BC) is still characterized by high morbidity and mortality. A specific BC subtype named triple negative BC (TNBC) lacks estrogen and progesterone receptors (ER and PR, respectively) and is characterized by the absence of overexpression/amplification of human epidermal growth factor receptor 2 (HER2). The androgen receptor (AR) is expressed in TNBC, although its function in these cancers is still debated. Moreover, few therapeutic options are currently available for the treatment of TNBC. In this study, we have used TNBC-derived MDA-MB231 and MDA-MB453 cells that, albeit at different extent, both express AR. Androgen challenging induces migration and invasiveness of these cells. Use of the anti-androgen bicalutamide or AR knockdown experiments show that these effects depend on AR. Furthermore, the small peptide, S1, which mimics the AR proline-rich motif responsible for the interaction of AR with SH3-Src, reverses the effects in both cell lines, suggesting that the assembly of a complex made up of AR and Src drives the androgen-induced motility and invasiveness. Co-immunoprecipitation experiments in androgen-treated MDA-MB231 and MDA-MB453 cells show that the AR/Src complex recruits p85α, the regulatory subunit of PI3-K. In such a way, the basic machinery leading to migration and invasiveness is turned-on. The S1 peptide inhibits motility and invasiveness of TNBC cells and disrupts the AR/Src/p85α complex assembly in MDA-MB231 cells. This study shows that the rapid androgen activation of Src/PI3-K signaling drives migration and invasiveness of TNBC cells and suggests that the S1 peptide is a promising therapeutic option for these cancers.

Estrogens Modulate Somatostatin Receptors Expression and Synergize With the Somatostatin Analog Pasireotide in Prostate Cells

Prostate cancer (PC) is one of the most frequently diagnosed cancers and a leading cause of cancer-related deaths in Western society. Current PC therapies prevalently target the functions of androgen receptor (AR) and may only be effective within short time periods, beyond which the majority of PC patients progress to castration-resistant PC (CRPC) and metastatic disease. The role of estradiol/estradiol receptor (ER) axis in prostate transformation and PC progression is well established. Further, considerable efforts have been made to investigate the mechanism by which somatostatin (SST) and somatostatin receptors (SSTRs) influence PC growth and progression. A number of therapeutic strategies, such as the combination of SST analogs with other drugs, show, indeed, strong promise. However, the effect of the combined treatment of SST analogs and estradiol on proliferation, epithelial mesenchyme transition (EMT) and migration of normal- and cancer-derived prostate cells has not been investigated so far. We now report that estradiol plays anti-proliferative and pro-apoptotic effect in non-transformed EPN prostate cells, which express both ERα and ERβ. A weak apoptotic effect is observed in transformed CPEC cells that only express low levels of ERβ. Estradiol increases, mainly through ERα activation, the expression of SSTRs in EPN, but not CPEC cells. As such, the hormone enhances the anti-proliferative effect of the SST analog, pasireotide in EPN, but not CPEC cells. Estradiol does not induce EMT and the motility of EPN cells, while it promotes EMT and migration of CPEC cells. Addition of pasireotide does not significantly modify these responses. Altogether, our results suggest that pasireotide may be used, alone or in combination with other drugs, to limit the growth of prostate proliferative diseases, provided that both ER isoforms (α and β) are present. Further investigations are needed to better define the cross talk between estrogens and SSTRs as well as its role in PC.

Deregulation of ATG9A by impaired AR signaling induces autophagy in prostate stromal fibroblasts and promotes BPH progression

The activation of androgen receptor (AR) signaling plays an essential role in both prostate stromal cells and epithelial cells during the development of benign prostatic hyperplasia (BPH). Here we demonstrated that androgen ablation after 5α-reductase inhibitor (5-ARI) treatment induced autophagy in prostate stromal fibroblasts inhibiting cell apoptosis. In addition, we found that ATG9A expression was increased after androgen ablation, which facilitated autophagic flux development. Knockdown of ATG9A not only inhibited autophagy notably in prostate stromal fibroblasts, but also reduced the volumes of prostate stromal fibroblast and epithelial cell recombinant grafts in nude mice. In conclusion, our findings suggested that ATG9A upregulation after long-term 5-ARI treatment constitutes a possible mechanism of BPH progression. Thus, combined treatment with 5-ARI and autophagy inhibitory agents would reduce the risk of BPH progression.

Estrogens and Their Receptors in Prostate Cancer: Therapeutic Implications

A major challenge in clinical management of prostate cancer (PC) is to limit tumor growth and prevent metastatic spreading. Considerable efforts have been made to discover new compounds for PC therapy and recent years have seen promising progress in this field. Pharmacological approaches have been designed to achieve benefits in PC treatment and avoid the negative side effects resulting from administration of antagonists or agonists or new drugs. Nonetheless, the currently available therapies frequently induce resistance and PC progresses toward castration-resistant forms that can be caused by the androgen receptor reactivation and/or mutations, or derangement of signaling pathways. Preclinical and clinical findings have also shown that other nuclear receptors are frequently altered in PC. In this review, we focus on the role of estradiol/estradiol receptor (ER) axis, which controls PC growth and progression. Selective targeting of ER subtypes (α or β) may be an attractive way to limit the growth and spreading of prostatic cancer cells.

Androgens trigger different growth responses in genetically identical human hair follicles in organ culture that reflect their epigenetic diversity in life

Male sex hormones-androgens-regulate male physique development. Without androgen signaling, genetic males appear female. During puberty, increasing androgens harness the hair follicle's unique regenerative ability to replace many tiny vellus hairs with larger, darker terminal hairs ( e.g., beard). Follicle response is epigenetically varied: some remain unaffected ( e.g., eyelashes) or are inhibited, causing balding. How sex steroid hormones alter such developmental processes is unclear, despite high incidences of hormone-driven cancer, hirsutism, and alopecia. Unfortunately, existing development models are not androgen sensitive. Here, we use hair follicles to establish an androgen-responsive human organ culture model. We show that women's intermediate facial follicles respond to men's higher androgen levels by synthesizing more hair over several days, unlike donor-matched, androgen-insensitive, terminal follicles. We demonstrate that androgen receptors-androgen-activated gene transcription regulators-are required and are present in vivo within these follicles. This is the first human organ that involves multiple cell types that responds appropriately to hormones in prolonged culture, in a way which mirrors its natural behavior. Thus, intermediate hair follicles offer a hormone-switchable human model with exceptional, unique availability of genetically identical, but epigenetically hormone-insensitive, terminal follicles. This should enable advances in understanding sex steroid hormone signaling, gene regulation, and developmental and regenerative systems and facilitate better therapies for hormone-dependent disorders.-Miranda, B. H., Charlesworth, M. R., Tobin, D. J., Sharpe, D. T., Randall, V. A. Androgens trigger different growth responses in genetically identical human hair follicles in organ culture that reflect their epigenetic diversity in life.

Differential protein expression profile in the hypothalamic GT1-7 cell line after exposure to anabolic androgenic steroids

The abuse of anabolic androgenic steroids (AAS) has been considered a major public health problem during decades. Supraphysiological doses of AAS may lead to a variety of neuroendocrine problems. Precisely, the hypothalamic-pituitary-gonadal (HPG) axis is one of the body systems that is mainly influenced by steroidal hormones. Fluctuations of the hormonal milieu result in alterations of reproductive function, which are made through changes in hypothalamic neurons expressing gonadotropin-releasing hormone (GnRH). In fact, previous studies have shown that AAS modulate the activity of these neurons through steroid-sensitive afferents. To increase knowledge about the cellular mechanisms induced by AAS in GnRH neurons, we performed proteomic analyses of the murine hypothalamic GT1-7 cell line after exposure to 17α-methyltestosterone (17α-meT; 1 μM). These cells represent a good model for studying regulatory processes because they exhibit the typical characteristics of GnRH neurons, and respond to compounds that modulate GnRH in vivo. Two-dimensional difference in gel electrophoresis (2D-DIGE) and mass spectrometry analyses identified a total of 17 different proteins that were significantly affected by supraphysiological levels of AAS. Furthermore, pathway analyses showed that modulated proteins were mainly associated to glucose metabolism, drug detoxification, stress response and cell cycle. Validation of many of these proteins, such as GSTM1, ERH, GAPDH, PEBP1 and PDIA6, were confirmed by western blotting. We further demonstrated that AAS exposure decreased expression of estrogen receptors and GnRH, while two important signaling pathway proteins p-ERK, and p-p38, were modulated. Our results suggest that steroids have the capacity to directly affect the neuroendocrine system by modulating key cellular processes for the control of reproductive function.

Androgen receptor dysfunction as a prevalent manifestation in young male carriers of a FLNA gene mutation

Androgenic actions require the proper signal transmission by the androgen receptor (AR), a nuclear transcription factor. This is initially located in the cell cytoplasm and should translocates to the nucleus to interact with DNA. AR functional impairment causes diverse blockage degrees of androgenic steroid action, known as androgen insensitivity syndromes. Filamin A, a protein coded by the FLNA gene, is a co-activator of various cytoplasmic factors, including AR. The mutational inactivation of the FLNA gene induces insufficiency of translocation and activation of AR. Consequently, it causes a developmental disorder of the male gonad and hypogonadism, similar to those observed in partial androgen insensitivity. We report two brothers carrying a loss-of-function mutation of FNLA with gonadal differentiation disorder and hypospadias. Specific staining for AR shows almost an absolute absence of these receptors in the testicular tissue. This association recommends investigating a possible mutational inactivation of the FLNA gene in patients with cryptorchidism and epididymo-testicular dissociation. The study is especially indicated when the family history, more often that of the mother, is suggestive. Likewise, growth and gonadal development of all male patients carrying this genetic trait should be monitored since childhood.

Non-Genomic Actions of the Androgen Receptor in Prostate Cancer

Androgen receptor (AR) is a validated drug target for prostate cancer based on its role in proliferation, survival, and metastases of prostate cancer cells. Unfortunately, despite recent improvements to androgen deprivation therapy and the advent of better antiandrogens with a superior affinity for the AR ligand-binding domain (LBD), most patients with recurrent disease will eventually develop lethal metastatic castration-resistant prostate cancer (CRPC). Expression of constitutively active AR splice variants that lack the LBD contribute toward therapeutic resistance by bypassing androgen blockade and antiandrogens. In the canonical pathway, binding of androgen to AR LBD triggers the release of AR from molecular chaperones which enable conformational changes and protein-protein interactions to facilitate its nuclear translocation where it regulates the expression of target genes. However, preceding AR function in the nucleus, initial binding of androgen to AR LBD in the cytoplasm may already initiate signal transduction pathways to modulate cellular proliferation and migration. In this article, we review the significance of signal transduction pathways activated by rapid, non-genomic signaling of the AR during the progression to metastatic CRPC and put into perspective the implications for current and novel therapies that target different domains of AR.

Androgen Signaling in Esophageal Adenocarcinoma Cell Lines In Vitro

BACKGROUND

We showed previously that nuclear localization of the androgen receptor (AR) and expression of the androgen-responsive gene FK506-binding protein 5 (FKBP5) in esophageal adenocarcinoma (EAC) tissues were associated with decreased patient survival, suggesting a role for androgens in this cancer.

AIM

To investigate the effect of the AR ligand 5α-dihydrotestosterone (DHT) on AR-expressing EAC cell lines in vitro.

METHODS AND RESULTS

In tissue resection specimens from EAC patients, FKBP5 expression was positively associated with proliferation as measured by Ki-67 expression. We stably transduced AR into three AR-negative EAC cell lines, OE33, JH-EsoAd1, and OE19, to investigate androgen signaling in vitro. In the AR-expressing cell lines, 10 nM DHT, the concentration typically used to study AR signaling, induced changes in the expression of androgen-responsive genes and inhibited proliferation by inducing cell cycle arrest and senescence. At lower DHT concentrations near the half maximal inhibitory concentration (IC50), the AR-expressing cell lines proliferated and there were changes in the expression of androgen-responsive genes. In direct co-culture with cancer-associated fibroblast-like PShTert myofibroblasts, 10 nM DHT induced changes in the expression of androgen-responsive genes but did not inhibit proliferation.

CONCLUSIONS

This is the first study to show that EAC cell lines respond to androgen in vitro. Proliferation together with the expression of androgen-responsive genes was dependent on the concentration of DHT, or the presence of a permissive microenvironment, consistent with observations in the tissues. These findings are consistent with a role for androgen signaling in EAC.

Extranuclear partners of androgen receptor: at the crossroads of proliferation, migration, and neuritogenesis

In this review, we focus on the role played by the protein partners of ligand-activated extranuclear androgen receptor (AR) in the final effects of hormone action, such as proliferation, migration, and neuritogenesis. The choice of AR partner, at least in part, depends on cell type. Androgen-activated receptor directly associates with cytoplasmic Src tyrosine kinase in epithelial cells, whereas in mesenchymal and neuronal cells, it prevalently interacts with filamin A. In the former, proliferation represents the final hormonal outcome, whereas in the latter, either migration or neuritogenesis, respectively, occurs. Furthermore, AR partner filamin A is replaced with Src when mesenchymal cells are stimulated with very low androgen concentrations. Consequently, the migratory effect is replaced by mitogenesis. Use of peptides that prevent receptor/partner assembly abolishes the effects that are dependent on their association and offers new therapeutic approaches to AR-related diseases. Perturbation of migration is often associated with metastatic spreading in cancer. In turn, cell cycle aberration causes tumors to grow faster, whereas toxic signaling triggers neurodegenerative events in the CNS. Here, we provide examples of new tools that interfere in rapid androgen effects, including migration, proliferation, and neuronal differentiation, together with their potential therapeutic applications in AR-dependent diseases-mainly prostate cancer and neurodegenerative disorders.-Castoria, G., Auricchio, F., Migliaccio, A. Extranuclear partners of androgen receptor: at the crossroads of proliferation, migration, and neuritogenesis.

Prostate cancer stem cells: the role of androgen and estrogen receptors

Prostate cancer is one of the most commonly diagnosed cancers in men, and androgen deprivation therapy still represents the primary treatment for prostate cancer patients. This approach, however, frequently fails and patients develop castration-resistant prostate cancer, which is almost untreatable.

Cancer cells are characterized by a hierarchical organization, and stem/progenitor cells are endowed with tumor-initiating activity. Accumulating evidence indicates that prostate cancer stem cells lack the androgen receptor and are, indeed, resistant to androgen deprivation therapy. In contrast, these cells express classical (α and/or β) and novel (GPR30) estrogen receptors, which may represent new putative targets in prostate cancer treatment.

In the present review, we discuss the still-debated mechanisms, both genomic and non-genomic, by which androgen and estradiol receptors (classical and novel) mediate the hormonal control of prostate cell stemness, transformation, and the continued growth of prostate cancer. Recent preclinical and clinical findings obtained using new androgen receptor antagonists, anti-estrogens, or compounds such as enhancers of androgen receptor degradation and peptides inhibiting non-genomic androgen functions are also presented. These new drugs will likely lead to significant advances in prostate cancer therapy.

Celastrol Induces Autophagy by Targeting AR/miR-101 in Prostate Cancer Cells

Autophagy is an evolutionarily conserved process responsible for the degradation and recycling of cytoplasmic components through autolysosomes. Targeting AR axis is a standard strategy for prostate cancer treatment; however, the role of AR in autophagic processes is still not fully understood. In the present study, we found that AR played a negative role in AR degrader celastrol-induced autophagy. Knockdown of AR in AR-positive prostate cancer cells resulted in enhanced autophagy. Ectopic expression of AR in AR-negative prostate cancer cells, or gain of function of the AR signaling in AR-positive cells, led to suppression of autophagy. Since miR-101 is an inhibitor of autophagy and its expression was decreased along with AR in the process of celastrol-induced autophagy, we hypothesize that AR inhibits autophagy through transactivation of miR-101. AR binding site was defined in the upstream of miR-101 gene by luciferase reporter and ChIP assays. MiR-101 expression correlated with AR status in prostate cancer cell lines. The inhibition of celastrol-induced autophagy by AR was compromised by blocking miR-101; while transfection of miR-101 led to inhibition of celastrol-induced autophagy in spite of AR depletion. Furthermore, mutagenesis of the AR binding site in miR-101 gene led to decreased suppression of autophagy by AR. Finally, autophagy inhibition by miR-101 mimic was found to enhance the cytotoxic effect of celastrol in prostate cancer cells. Our results demonstrate that AR inhibits autophagy via transactivation of miR-101, thus combination of miR-101 mimics with celastrol may represent a promising therapeutic approach for treating prostate cancer.

Cross-talk between androgen receptor/filamin A and TrkA regulates neurite outgrowth in PC12 cells

Steroids and growth factors control neuronal development through their receptors under physiological and pathological conditions. We show that PC12 cells harbor endogenous androgen receptor (AR), whose inhibition or silencing strongly interferes with neuritogenesis stimulated by the nonaromatizable synthetic androgen R1881 or NGF. This implies a role for AR not only in androgen signaling, but also in NGF signaling. In turn, a pharmacological TrkA inhibitor interferes with NGF- or androgen-induced neuritogenesis. In addition, androgen or NGF triggers AR association with TrkA, TrkA interaction with PI3-K δ, and downstream activation of PI3-K δ and Rac in PC12 cells. Once associated with AR, filamin A (FlnA) contributes to androgen or NGF neuritogenesis, likely through its interaction with signaling effectors, such as Rac. This study thus identifies a previously unrecognized reciprocal cross-talk between AR and TrkA, which is controlled by β1 integrin. The contribution of FlnA/AR complex and PI3-K δ to neuronal differentiation by androgens and NGF is also novel. This is the first description of AR function in PC12 cells.

Androgen Receptor Targeted Conjugate for Bimodal Photodynamic Therapy of Prostate Cancer in Vitro

Prostate cancer (PC) represents the most common type of cancer among males and is the second leading cause of cancer death in men in Western society. Current options for PC therapy remain unsatisfactory, since they often produce uncomfortable long-term side effects, such as impotence (70%) and incontinence (5-20%) even in the first stages of the disease. Light-triggered therapies, such as photodynamic therapy, have the potential to provide important advances in the treatment of localized and partially metastasized prostate cancer. We have designed a novel molecular conjugate (DR2) constituted of a photosensitizer (pheophorbide a, Pba), connected to a nonsteroidal anti-androgen molecule through a small pegylated linker. This study aims at investigating whether DR2 represents a valuable approach for PC treatment based on light-induced production of single oxygen and nitric oxide (NO) in vitro. Besides being able to efficiently bind the androgen receptor (AR), the 2-trifluoromethylnitrobenzene ring on the DR2 backbone is able to release cytotoxic NO under the exclusive control of light, thus augmenting the general photodynamic effect. Although DR2 is similarly internalized in cells expressing different levels of androgen receptor, the AR ligand prevents its efflux through the ABCG2-pump. In vitro phototoxicity experiments demonstrated the ability of DR2 to kill cancer cells more efficiently than Pba, while no dark toxicity was observed. Overall, the presented approach is very promising for further development of AR-photosensitizer conjugates in the multimodal photodynamic treatment of prostate cancer.

Non-genomic androgen action regulates proliferative/migratory signaling in stromal cells

Prostate cancer (PCa) is the major cause of cancer-related death among the male population of Western society, and androgen-deprivation therapy (ADT) represents the first line in PCa treatment. However, although androgen receptor (AR) expression is maintained throughout the various stages of PCa, ADT frequently fails. Clinical studies have demonstrated that different androgen/AR signaling pathways operate in target tissues. AR stimulates growth and transformation of target cells, but under certain conditions slows down their proliferation. In this review, we discuss the role of AR in controlling different functions of mesenchymal and transformed mesenchymal cells. Findings here presented support the role of AR in suppressing proliferation and stimulating migration of stromal cells, with implications for current approaches to cancer therapy.