Monoamine oxidase A mediates prostate tumorigenesis and cancer metastasis

Monoamine oxidase B levels are highly expressed in human gliomas and are correlated with the expression of HiF-1α and with transcription factors Sp1 and Sp3

Monoamine oxidases A and B (MAOA and MAOB) are highly expressed in many cancers. Here we investigated the level of MAOB in gliomas and confirmed its high expression. We found that MAOB levels correlated with tumor grade and hypoxia-inducible factor 1-alpha (HiF-1α) expression. HiF-1α was localized to the nuclei in high-grade gliomas, but it was primarily cytosolic in low-grade gliomas and normal human astrocytes. Expression of both glial fibrillary acidic protein (GFAP) and MAOB are correlated to HiF-1α expression levels. Levels of MAOB are correlated by the levels of transcription factor Sp3 in the majority of GBM examined, but this control of MAOB expression by Sp3 in low grade astrocytic gliomas is significantly different from control in the in the majority of glioblastomas. The current findings support previous suggestions that MAOB can be exploited for the killing of cancer cells. Selective cell toxicity can be achieved by designing non-toxic prodrugs that require MAOB for their catalytic conversion into mature cytotoxic chemotherapeutics.

Phytochemical and ethnomedicinal study of Huperzia species used in the traditional medicine of Saraguros in Southern Ecuador; AChE and MAO inhibitory activity

ETHNOBOTANICAL AND ETHNOMEDICINAL RELEVANCE

This study concerns seven Huperzia species (Lycopodiaceae), namely H. brevifolia, H. columnaris, H. compacta, H. crassa, H. espinosana, H. tetragona, H. weberbaueri, which are considered sacred plants by the Saraguro community, living in the Southern Andes of Ecuador; these plants are widely used in traditional medicine and ritual ceremonies.

MATERIAL AND METHODS

The plants were selected on the basis of written interviews with 10 visionary healers (yachak) (2 women, 8 men), indicated as the most credible by the Saraguro Healers Council. The Informant Consensus Factor (F_ic) was determined. The first phytochemical study of the plants was performed by standard procedures, while the AChE and MAO-A inhibition by fractions enriched in high MW alkaloids, was measured in vitro.

AIMS OF THE STUDY

i) to investigate the uses of some Huperzia plants in healing and magical-religious practices of Saraguros; ii) to identify the main components of plant hydromethanolic extracts; iiì) to test the effects of alkaloidal fractions on the activity of two enzymes linked to mental health.

RESULTS

All the interviewed Saraguro yachak showed a high consensus about the uses of the seven Huperzia plants as purgatives and against supernatural diseases, such as the "espanto" (startle). In admixtures with other plants, some species also induce a state of trance or hallucinations in participants in magical-religious rituals. GC-MS of the volatile alkaloid fractions allowed the identification of some lycodine-type and lycopodine-type alkaloids (1-5) in H. compacta, H. columnaris, and H. tetragona. The flavones selgin) (6) and tricin (7) were isolated from H. brevifolia and H. espinosana. Tricin (7) was also detected in the other five species. The rare serratene triterpenes serratenediol (8) serratenediol-3-O-acetate (9), 21-episerratenediol (10), and 21-episerratenediol-3-O-acetate (11) were isolated from H. crassa. In addition, the presence of an unprecedented group of high molecular weight alkaloids has been determined. Alkaloid fractions of H. brevifolia, H. compacta, H. espinosana, and H. tetragona significantly inhibited AChE and MAO-A activities in vitro.

CONCLUSIONS

The first phytochemical and ethnopharmacological study of seven Huperzia plants, widely used by Saraguro healers, led to the identification of several alkaloids and triterpenoids with different remarkable biological activities. In addition, alkaloid fractions exhibited a significant AChE and MAO-A inhibitory activity. These results may support the use of these plants in brews prepared for inducing psychoactive effects in participants in magical-religious ceremonies. This study confirms the rich traditional medical knowledge of Saraguro healers which must be documented and preserved for future generations.

DAB2IP regulates EMT and metastasis of prostate cancer through targeting PROX1 transcription and destabilizing HIF1α protein

Prospero-related homeobox 1 (PROX1) is an essential regulator in lymphangiogenesis and has been implicated in both oncogenic and tumor-suppressive functions in many types of human cancers. However, the role of PROX1 in prostate cancer (PCa) remains poorly understood. In this study, based on different PCa cell lines and knockout mice, we showed that PROX1 could be suppressed by DAB2IP, a novel member of the Ras GTPase-activating protein family and a critical player in control of epithelial-mesenchymal transition (EMT) and PCa metastasis. Mechanistically, PROX1 overexpression in DAB2IP-deficient PCa cells could enhance the accumulation of HIF1α protein by inhibiting ubiquitin pathway and then consequently induce an EMT response, which is characterized by repression of E-cadherin, up-regulation of vimentin and matrix metallopeptidases (MMPs) and enhancement of cell migration. Together, our data provides a new insight into mechanism that DAB2IP regulates EMT and PCa metastasis, especially points out the potential roles of its downstream PROX1/HIF1α signaling in a unique non-skeletal metastasis of PCa.

Drinking water: a risk factor for high incidence of esophageal cancer in Anyang, China

Anyang is known to be a high-incidence area of esophageal cancer (EC) in China. Among a long list of risk factors, the quality of drinking water was evaluated. We have selected 3806 individuals and collected 550 drinking water samples correspondent with this not-matched case-control survey. There are 531 EC patients included based on Population Cancer Registry from 92 townships, of which 3275 controls with long-lived aged over 90 years and free from EC are used as controls in the same regions. Our result suggests that the quality of drinking water is a highly associated risk factor for EC. The residential ecological environment and the quality of water resource positively link with each other. The analysis of water samples also demonstrated that the concentrations of methyl ethylamine, morpholine, N-methylbenzylamine, nitrate and chloride in water from springs and rivers are higher than those in well and tap water (P = 0.001). Micronuclei formation tests show that well water and tap water in these regions have no mutagenicity.

Evaluation of the Isoflavone Genistein as Reversible Human Monoamine Oxidase-A and -B Inhibitor

Monoamine oxidases inhibitors (MAOIs) are effective therapeutic drugs for managing Parkinson's disease (PD) and depression. However, their irreversibility may lead to rare but serious side effects. As finding safer and reversible MAOIs is our target, we characterized the recombinant human (h) MAO-A and MAO-B inhibition potentials of two common natural isoflavones, genistein (GST) and daidzein (DZ) using luminescence assay. The results obtained showed that DZ exhibits partial to no inhibition of the isozymes examined while GST inhibited hMAO-B (IC₅₀ of 6.81 μM), and its hMAO-A inhibition was more potent than the standard deprenyl. Furthermore, the reversibility, mode of inhibition kinetics, and tyramine oxidation of GST were examined. GST was a time-independent reversible and competitive hMAO-A and hMAO-B inhibitor with a lower K_i of hMAO-B (1.45 μM) than hMAO-A (4.31 μM). GST also inhibited hMAO-B tyramine oxidation and hydrogen peroxide production more than hMAO-A. Docking studies conducted indicated that the GST reversibility and hMAO-B selectivity of inhibition may relate to C5-OH effects on its orientation and its interactions with the threonine 201 residue of the active site. It was concluded from this study that the natural product GST has competitive and reversible MAOs inhibitions and may be recommended for further investigations as a useful therapeutic agent for Parkinson's disease.

Monoamine oxidase A (MAO A) inhibitors decrease glioma progression

Glioblastoma (GBM) is an aggressive brain tumor which is currently treated with temozolomide (TMZ). Tumors usually become resistant to TMZ and recur; no effective therapy is then available. Monoamine Oxidase A (MAO A) oxidizes monoamine neurotransmitters resulting in reactive oxygen species which cause cancer. This study shows that MAO A expression is increased in human glioma tissues and cell lines. MAO A inhibitors, clorgyline or the near-infrared-dye MHI-148 conjugated to clorgyline (NMI), were cytotoxic for glioma and decreased invasion in vitro. Using the intracranial TMZ-resistant glioma model, clorgyline or NMI alone or in combination with low-dose TMZ reduced tumor growth and increased animal survival. NMI was localized specifically to the tumor. Immunocytochemistry studies showed that the MAO A inhibitor reduced proliferation, microvessel density and invasion, and increased macrophage infiltration. In conclusion, we have identified MAO A inhibitors as potential novel stand-alone drugs or as combination therapy with low dose TMZ for drug-resistant gliomas. NMI can also be used as a non-invasive imaging tool. Thus has a dual function for both therapy and diagnosis.

Large-scale evaluation of SLC18A2 in prostate cancer reveals diagnostic and prognostic biomarker potential at three molecular levels

Limitations of current diagnostic and prognostic tools for prostate cancer (PC) have led to over-diagnosis and over-treatment. Here, we investigate the biomarker potential of the SLC18A2 (VMAT2) gene for PC at three molecular levels. Thus, SLC18A2 promoter methylation was analyzed in 767 malignant and 78 benign radical prostatectomy (RP) samples using methylation-specific qPCR and Illumina 450K methylation microarray data. SLC18A2 transcript levels were assessed in 412 malignant and 45 benign RP samples using RNAseq data. SLC18A2 protein was evaluated by immunohistochemistry in 502 malignant and 305 benign RP samples. Cancer-specificity of molecular changes was tested using Mann-Whitney U tests and/or receiver operating characteristic (ROC) analyses. Log rank, uni- and multivariate Cox regression tests were used for survival analyses. We found that SLC18A2 promoter hypermethylation was highly cancer-specific (area under the curve (AUC): 0.923-0.976) and associated with biochemical recurrence (BCR) after RP in univariate analyses. SLC18A2 transcript levels were reduced in PC and had independent prognostic value for BCR after RP (multivariate HR 0.13, P < 0.05). Likewise, SLC18A2 protein was down-regulated in PC (AUC 0.898) and had independent prognostic value for BCR (multivariate HR 0.51, P < 0.05). Reduced SLC18A2 protein expression was also associated with poor overall survival in univariate analysis (HR 0.29, P < 0.05). Our results highlight SLC18A2 as a new promising methylation marker candidate for PC diagnosis. Furthermore, SLC18A2 expression (RNA and protein) showed promising prognostic potential beyond routine clinicopathological variables. Thus, novel SLC18A2-based molecular tests could have useful future applications for PC detection and identification of high-risk patients.

Reactive oxygen species mediate oxaliplatin-induced epithelial-mesenchymal transition and invasive potential in colon cancer

Therapeutic benefits offered by common chemotherapy drugs, such as oxaliplatin, are limited due to the development of resistance, which contributes to treatment failure and metastasis. The epithelial-mesenchymal transition (EMT) is a key event contributing to the development of resistance to chemotherapeutics. Although the relationship between oxaliplatin and chemotherapy resistance has been described for decades, the molecular mechanisms have remained elusive. The aim of the present study was to investigate the underlying mechanisms of oxaliplatin-mediated metastasis. Here, we identify reactive oxygen species (ROS) as mediators that promote the oxaliplatin-induced EMT. Following oxaliplatin treatment, the messenger RNA (mRNA) levels of most peroxiredoxin family genes, except for peroxiredoxin 1 (prdx1) gene, were constant or even decreased, resulting in ROS abundance. And the antioxidant guardian Nrf2 was unconspicuously raised both transcriptionally and translationally with oxaliplatin treatment as compared to those induced by topotecan treatment, which has been proved with no induced metastasis. In addition, the study evaluated high levels of ROS leading to EMT via activation of the known oncogenes Akt and Snail. Using the Akt inhibitor LY294002 or knocking down Snail expression via RNA interference (RNAi) reversed the effects of oxaliplatin on the EMT and metastasis. Our studies establish a role for the ROS-Akt-Snail axis as a mechanism by which chemotherapeutics induce EMT and cancer metastasis.

Pharmacology and Clinical Drug Candidates in Redox Medicine

SIGNIFICANCE

Oxidative stress is suggested to be a disease mechanism common to a wide range of disorders affecting human health. However, so far, the pharmacotherapeutic exploitation of this, for example, based on chemical scavenging of pro-oxidant molecules, has been unsuccessful.

RECENT ADVANCES

An alternative emerging approach is to target the enzymatic sources of disease-relevant oxidative stress. Several such enzymes and isoforms have been identified and linked to different pathologies. For some targets, the respective pharmacology is quite advanced, that is, up to late-stage clinical development or even on the market; for others, drugs are already in clinical use, although not for indications based on oxidative stress, and repurposing seems to be a viable option.

CRITICAL ISSUES

For all other targets, reliable preclinical validation and drug ability are key factors for any translation into the clinic. In this study, specific pharmacological agents with optimal pharmacokinetic profiles are still lacking. Moreover, these enzymes also serve largely unknown physiological functions and their inhibition may lead to unwanted side effects.

FUTURE DIRECTIONS

The current promising data based on new targets, drugs, and drug repurposing are mainly a result of academic efforts. With the availability of optimized compounds and coordinated efforts from academia and industry scientists, unambiguous validation and translation into proof-of-principle studies seem achievable in the very near future, possibly leading towards a new era of redox medicine.

Reactive Oxygen-Related Diseases: Therapeutic Targets and Emerging Clinical Indications

SIGNIFICANCE

Enhanced levels of reactive oxygen species (ROS) have been associated with different disease states. Most attempts to validate and exploit these associations by chronic antioxidant therapies have provided disappointing results. Hence, the clinical relevance of ROS is still largely unclear.

RECENT ADVANCES

We are now beginning to understand the reasons for these failures, which reside in the many important physiological roles of ROS in cell signaling. To exploit ROS therapeutically, it would be essential to define and treat the disease-relevant ROS at the right moment and leave physiological ROS formation intact. This breakthrough seems now within reach.

CRITICAL ISSUES

Rather than antioxidants, a new generation of protein targets for classical pharmacological agents includes ROS-forming or toxifying enzymes or proteins that are oxidatively damaged and can be functionally repaired.

FUTURE DIRECTIONS

Linking these target proteins in future to specific disease states and providing in each case proof of principle will be essential for translating the oxidative stress concept into the clinic.

Role of epithelial mesenchymal transition in prostate tumorigenesis

Globally, the cancer associated deaths are generally attributed to the spread of cancerous cells or their features to the nearby or distant secondary organs by a process known as metastasis. Among other factors, the metastatic dissemination of cancer cells is attributed to the reactivation of an evolutionary conserved developmental program known as epithelial to mesenchymal transition (EMT). During EMT, fully differentiated epithelial cells undergo a series of dramatic changes in their morphology, along with loss of cell to cell contact and matrix remodeling into less differentiated and invasive mesenchymal cells. Many studies provide evidence for the existence of EMT like states in prostate cancer (PCa) and suggest its possible involvement in PCa progression and metastasis. At the same time, the lack of conclusive evidence regarding the presence of full EMT in human PCa samples has somewhat dampened the interest in the field. However, ongoing EMT research provides new perspectives and unveils the enormous potential of this field in tailoring new therapeutic regimens for PCa management. This review summarizes the role of many transcription factors and other molecules that drive EMT during prostate tumorigenesis.

Curcumin inhibits cancer-associated fibroblast-driven prostate cancer invasion through MAOA/mTOR/HIF-1α signaling

Cancer-associated fibroblasts (CAFs) are key determinants in the malignant progression of cancer, supporting tumorigenesis and metastasis. CAFs also mediate epithelial to mesenchymal transition (EMT) in tumor cells and their achievement of stem cell traits. Curcumin has recently been found to possess anticancer activities via its effect on a variety of biological pathways involved in cancer progression. In this study, we found that CAFs could induce prostate cancer cell EMT and invasion through a monoamine oxidase A (MAOA)/mammalian target of rapamycin (mTOR)/hypoxia-inducible factor-1α (HIF-1α) signaling pathway, which exploits reactive oxygen species (ROS) to drive a migratory and aggressive phenotype of prostate carcinoma cells. Moreover, CAFs was able to increase CXC chemokine receptor 4 (CXCR4) and interleukin-6 (IL-6) receptor expression in prostate cancer cells. However, curcumin abrogated CAF-induced invasion and EMT, and inhibited ROS production and CXCR4 and IL-6 receptor expression in prostate cancer cells through inhibiting MAOA/mTOR/HIF-1α signaling, thereby supporting the therapeutic effect of curcumin in prostate cancer.

Heptamethine carbocyanine dye-mediated near-infrared imaging of canine and human cancers through the HIF-1α/OATPs signaling axis

Near-infrared (NIR) fluorescence imaging agents are promising tools for noninvasive cancer imaging. This study explored the specific uptake and retention of a NIR heptamethine carbocyanine MHI-148 dye by canine cancer cells and tissues and human prostate cancer (PCa) specimens and also the dye uptake mechanisms. The accumulation of MHI-148 was detected specifically in canine cancer cells and tissues and freshly harvested human PCa tissues xenografted in mice by NIR fluorescence microscopy and whole-body NIR optical imaging. Specific dye uptake in canine spontaneous tumors was further confirmed by PET imaging. Higher hypoxia-inducible factor-1α (HIF-1α) and organic anion-transporting polypeptide (OATP) protein and mRNA expression was demonstrated by multiplex quantum dots labeling and qPCR in tumors over that of normal tissues. Treating cancer cells with HIF-1α stabilizers activated HIF-1α downstream target genes, induced OATP superfamily gene expression and enhanced cellular uptake and retention of NIR dyes. Moreover, silencing HIF-1α by siRNA significantly decreased OATP mRNA expression and blocked NIR dye uptake in cancer cells. Together, these results demonstrated the preferential uptake of NIR dyes by canine and human cancer cells and tissues via the HIF-1α/OATPs signaling axis, which provides insights into future application of these dyes for cancer detection and treatment.

Near-infrared fluorescence heptamethine carbocyanine dyes mediate imaging and targeted drug delivery for human brain tumor

Brain tumors and brain metastases are among the deadliest malignancies of all human cancers, largely due to the cellular blood-brain and blood-tumor barriers that limit the delivery of imaging and therapeutic agents from the systemic circulation to tumors. Thus, improved strategies for brain tumor visualization and targeted treatment are critically needed. Here we identified and synthesized a group of near-infrared fluorescence (NIRF) heptamethine carbocyanine dyes and derivative NIRF dye-drug conjugates for effective imaging and therapeutic targeting of brain tumors of either primary or metastatic origin in mice, which is mechanistically mediated by tumor hypoxia and organic anion-transporting polypeptide genes. We also demonstrate that these dyes, when conjugated to chemotherapeutic agents such as gemcitabine, significantly restricted the growth of both intracranial glioma xenografts and prostate tumor brain metastases and prolonged survival in mice. These results show promise in the application of NIRF dyes as novel theranostic agents for the detection and treatment of brain tumors.

Molecular mechanism of monoamine oxidase A gene regulation under inflammation and ischemia-like conditions: key roles of the transcription factors GATA2, Sp1 and TBP

Monoamine oxidase A (MAOA) plays important roles in the pathogenesis of several neurological and cardiovascular disorders. The mechanism of transcriptional regulation of MAOA under basal and pathological conditions, however, remains incompletely understood. Here, we report systematic identification and characterization of cis elements and transcription factors that govern the expression of MAOA gene. Extensive computational analysis of MAOA promoter, followed by 5'-promoter deletion/reporter assays, revealed that the -71/-40 bp domain was sufficient for its basal transcription. Gel-shift and chromatin immunoprecipitation assays provided evidence of interactions of the transcription factors GATA-binding protein 2 (GATA2), Sp1 and TATA-binding protein (TBP) with this proximal promoter region. Consistently, over-expression of GATA2, Sp1 and TBP augmented MAOA promoter activity in a coordinated manner. In corroboration, siRNA-mediated down-regulation of GATA2/Sp1/TBP repressed the endogenous MAOA expression as well as transfected MAOA promoter activity. Tumor necrosis factor-α and forskolin activated MAOA transcription that was reversed by Sp1 siRNA; in support, tumor necrosis factor-α- and forskolin-induced activities were enhanced by ectopic over-expression of Sp1. On the other hand, MAOA transcription was diminished upon exposure of neuroblasts or cardiac myoblasts to ischemia-like conditions because of reduced binding of GATA2/Sp1/TBP with MAOA promoter. In conclusion, this study revealed previously unknown roles of GATA2, Sp1 and TBP in modulating MAOA expression under basal as well as pathophysiological conditions such as inflammation and ischemia, thus providing new insights into the molecular basis of aberrant MAOA expression in neuronal/cardiovascular disease states. Dysregulation of monoamine oxidase A (MAOA) have been implicated in several behavioral and neuronal disease states. Here, we identified three crucial transcription factors (GATA2, Sp1 and TBP) that regulate MAOA gene expression in a coordinated manner. Aberrant MAOA expression under pathophysiological conditions including inflammation and ischemia is mediated by altered binding of GATA2/Sp1/TBP with MAOA proximal promoter. Thus, these findings provide new insights into pathogenesis of several common diseases. GATA2, GATA-binding protein 2; Sp1, specificity protein 1; TBP, TATA-binding protein.

Dual inhibition of survivin and MAOA synergistically impairs growth of PTEN-negative prostate cancer

Background:

Survivin and monoamine oxidase A (MAOA) levels are elevated in prostate cancer (PCa) compared to normal prostate glands. However, the relationship between survivin and MAOA in PCa is unclear.

Methods:

We examined MAOA expression in the prostate lobes of a conditional PTEN-deficient mouse model mirroring human PCa, with or without survivin knockout. We also silenced one gene at a time and examined the expression of the other. We further evaluated the combination of MAOA inhibitors and survivin suppressants on the growth, viability, migration and invasion of PCa cells.

Results:

Survivin and MAOA levels are both increased in clinical PCa tissues and significantly associated with patients' survival. Survivin depletion delayed MAOA increase during PCa progression, and silencing MAOA decreased survivin expression. The combination of MAOA inhibitors and the survivin suppressants (YM155 and SC144) showed significant synergy on the inhibition of PCa cell growth, migration and invasion with concomitant decrease in survivin and MMP-9 levels.

Conclusions:

There is a positive feedback loop between survivin and MAOA expression in PCa. Considering that survivin suppressants and MAOA inhibitors are currently available in clinical trials and clinical use, their synergistic effects in PCa support a rapid translation of this combination to clinical practice.

Monoamine oxidase: radiotracer chemistry and human studies

Monoamine oxidase (MAO) oxidizes amines from both endogenous and exogenous sources thereby regulating the concentration of neurotransmitter amines such as serotonin, norepinephrine, and dopamine as well as many xenobiotics. MAO inhibitor drugs are used in the treatment of Parkinson's disease and in depression stimulating the development of radiotracer tools to probe the role of MAO in normal human biology and in disease. Over the past 30 years since the first radiotracers were developed and the first positron emission tomography (PET) images of MAO in humans were carried out, PET studies of brain MAO in healthy volunteers and in patients have identified different variables that have contributed to different MAO levels in brain and in peripheral organs. MAO radiotracers and PET have also been used to study the current and developing MAO inhibitor drugs including the selection of doses for clinical trials. In this article, we describe the following: (1) the development of MAO radiotracers; (2) human studies including the relationship of brain MAO levels to genotype, personality, neurological, and psychiatric disorders; and (3) examples of the use of MAO radiotracers in drug research and development. We will conclude with outstanding needs to improve the radiotracers that are currently used and possible new applications.

Monoamine oxidase A inhibitor-near-infrared dye conjugate reduces prostate tumor growth

Development of anti-cancer agents with high tumor-targeting specificity and efficacy is critical for modern multidisciplinary cancer research. Monoamine oxidase A (MAOA), a mitochondria-bound enzyme, degrades monoamine neurotransmitters and dietary monoamines. Recent evidence suggests a correlation between increased MAOA expression and prostate cancer (PCa) progression with poor outcomes for patients. MAOA induces epithelial-mesenchymal transition (EMT) and augments hypoxic effects by producing excess reactive oxygen species. Thus, development of MAOA inhibitors which selectively target tumors becomes an important goal in cancer pharmacology. Here we describe the design, synthesis, and in vitro and in vivo evaluation of NMI, a conjugate that combines a near-infrared dye for tumor targeting with the moiety derived from the MAOA inhibitor clorgyline. NMI inhibits MAOA with low micromolar IC50, suppresses PCa cell proliferation and colony formation, and reduces migration and invasion. In mouse PCa xenografts, NMI targets tumors with no detectable accumulation in normal tissues, providing effective reduction of the tumor burden. Analysis of tumor specimens shows reduction in Ki-67(+) and CD31(+) cells, suggesting a decrease of cell proliferation and angiogenesis and an increase in M30(+) cells, indicating increased apoptosis. Gene expression profiles of tumors treated with NMI demonstrate reduced expression of oncogenes FOS, JUN, NFKB, and MYC and cell cycle regulators CCND1, CCNE1, and CDK4/6, along with increases in the levels of tumor suppressor gene TP53, cell cycle inhibitors CDKN1A and CDKN2A, and MAOA-downstream genes that promote EMT, tumor hypoxia, cancer cell migration, and invasion. These data suggest that NMI exerts its effect through tumor-targeted delivery of a MAOA-inactivating group, making NMI a valuable anti-tumor agent.

Novel monoamine oxidase inhibitors: a patent review (2012 - 2014)

INTRODUCTION

Monoamine oxidase (MAO) inhibitors, despite the initial pharmacological interest, are used in clinic for their antidepressant effect and in the management of Parkinson symptoms, due to the established neuroprotective action. Efficacy and tolerability emerged from large-scale and randomized clinical trials.

AREAS COVERED

Thirty-six patents range from April 2012 to September 2014. The number of chemotypes with inhibitory effects on MAO is truly high (40 synthetic compounds, 22 natural products and 6 plant extracts reported and licensed), and the present review is comprehensive of all compounds, which have been patented for their relevance to clinical medicine in this period range (27 patents). Moreover, some of the collected patents deal with new formulations of compounds endowed with MAO inhibitory properties (two patents) and new therapeutic options/drug associations for already known MAO inhibitors (seven patents).

EXPERT OPINION

The patents reported in this review showed that the interest in this field is constant and mainly devoted to the study of selective MAO-B inhibitors, used as drugs for the treatment of neurological disorders. The development of novel human MAO inhibitors took advantage of the discovery of new therapeutic targets (cancer, hair loss, muscle dystrophies, cocaine addiction and inflammation), the recognized role of MAOs as molecular biomarkers and their activity in other tissues.

Molecular pathways and targets in prostate cancer

Prostate cancer co-opts a unique set of cellular pathways in its initiation and progression. The heterogeneity of prostate cancers is evident at earlier stages, and has led to rigorous efforts to stratify the localized prostate cancers, so that progression to advanced stages could be predicted based upon salient features of the early disease. The deregulated androgen receptor signaling is undeniably most important in the progression of the majority of prostate tumors. It is perhaps because of the primacy of the androgen receptor governed transcriptional program in prostate epithelium cells that once this program is corrupted, the consequences of the ensuing changes in activity are pleotropic and could contribute to malignancy in multiple ways. Following localized surgical and radiation therapies, 20-40% of patients will relapse and progress, and will be treated with androgen deprivation therapies. The successful development of the new agents that inhibit androgen signaling has changed the progression free survival in hormone resistant disease, but this has not changed the almost ubiquitous development of truly resistant phenotypes in advanced prostate cancer. This review summarizes the current understanding of the molecular pathways involved in localized and metastatic prostate cancer, with an emphasis on the clinical implications of the new knowledge.