Phosphodiesterase 11A (PDE11A) genetic variants may increase susceptibility to prostatic cancer

Cyclic nucleotide phosphodiesterases as drug targets

Cyclic nucleotides are synthesized by adenylyl and/or guanylyl cyclase, and downstream of this synthesis, the cyclic nucleotide phosphodiesterase families (PDEs) specifically hydrolyze cyclic nucleotides. PDEs control cyclic adenosine-3',5'monophosphate (cAMP) and cyclic guanosine-3',5'-monophosphate (cGMP) intracellular levels by mediating their quick return to the basal steady state levels. This often takes place in subcellular nanodomains. Thus, PDEs govern short-term protein phosphorylation, long-term protein expression, and even epigenetic mechanisms by modulating cyclic nucleotide levels. Consequently, their involvement in both health and disease is extensively investigated. PDE inhibition has emerged as a promising clinical intervention method, with ongoing developments aiming to enhance its efficacy and applicability. In this comprehensive review, we extensively look into the intricate landscape of PDEs biochemistry, exploring their diverse roles in various tissues. Furthermore, we outline the underlying mechanisms of PDEs in different pathophysiological conditions. Additionally, we review the application of PDE inhibition in related diseases, shedding light on current advancements and future prospects for clinical intervention. SIGNIFICANCE STATEMENT: Regulating PDEs is a critical checkpoint for numerous (patho)physiological conditions. However, despite the development of several PDE inhibitors aimed at controlling overactivated PDEs, their applicability in clinical settings poses challenges. In this context, our focus is on pharmacodynamics and the structure activity of PDEs, aiming to illustrate how selectivity and efficacy can be optimized. Additionally, this review points to current preclinical and clinical evidence that depicts various optimization efforts and indications.

Evaluate the Role of Phosphodiesterase, Myeloperoxidase and Iron in Oral Cancer

OBJECTIVE

The present study aimed to estimate the levels of phosphodiesterase (PDE), myeloperoxidase (MPO) and iron levels in patients with oral cancer.

METHOD

50 patients reporting to the Department of Oral Medicine and Radiology A.B. Shetty Memorial Institute of Dental Sciences, Deralakatte, Mangalore were recruited for the study after taking informed consent. The study group consists of 50 control groups with no complications and 50 oral cancer patients. A 5 ml venous Blood sample was taken, centrifuged and serum was collected for subsequent analysis. 50 normal control samples were also collected for comparison purposes. PDE, MPO and iron levels were estimated.

RESULTS

PDE levels were significantly elevated in the case group compared to the control. MPO and iron levels were significantly reduced in the case group compared to the control.

CONCLUSION

Immunological and biochemical assessment of oral precancer and cancer patients may help in earlier diagnosis and/or prognosis of these lesions. This may also serve in predicting the malignant potential of the pre-malignant lesions.

Prevalence and spectrum of cancer predisposition germline mutations in young patients with the common late-onset cancers

BACKGROUND

Pathogenic germline variants (PGVs) can play a vital role in the oncogenesis process in carriers. Previous studies have recognized that PGVs contribute to early onset of tumorigenesis in certain cancer types, for example, colorectal cancer and breast cancer. However, the reported prevalence data of cancer-associated PGVs were highly inconsistent due to nonuniform patient cohorts, sequencing methods, and prominent difficulties in pathogenicity interpretation of variants. In addition to the above difficulties, due to the rarity of cases, the prevalence of cancer PGV carriers in young cancer patients affected by late-onset cancer types has not been comprehensively evaluated to date.

METHODS

A total of 131 young cancer patients (1-29 years old at diagnosis) were enrolled in this study. The patients were affected by six common late-onset cancer types, namely, lung cancer, liver cancer, colorectal cancer, gastric cancer, renal cancer, and head-neck cancer. Cancer PGVs were identified and analyzed. based on NGS-based targeted sequencing followed by bioinformatic screening and strict further evaluations of variant pathogenicity.

RESULTS

Twenty-three cancer PGVs in 21 patients were identified, resulting in an overall PGV prevalence of 16.0% across the six included cancer types, which was approximately double the prevalence reported in a previous pancancer study. Nine of the 23 PGVs are novel, thus expanding the cancer PGV spectrum. Seven of the 23 (30.4%) PGVs are potential therapeutic targets of olaparib, with potential implications for clinical manipulation. Additionally, a small prevalence of somatic mutations of some classic cancer hallmark genes in young patients, in contrast to all-age patients, was revealed.

CONCLUSION

This study demonstrates the high prevalence of PGVs in young cancer patients with the common late-onset cancers and the potentially significant clinical implications of cancer PGVs, the findings highlight the value of PGV screening in young patients across lung cancer, liver cancer, colorectal cancer, gastric cancer, renal cancer, or head-neck cancer.

Functional characteristics and research trends of PDE11A in human diseases (Review)

cAMP and cGMP are important secondary messengers involved in cell regulation and metabolism driven by the G protein-coupled receptor. cAMP is converted via adenylyl cyclase (AC) and activates protein kinase A to phosphorylate intracellular proteins that mediate specific responses. cAMP signaling serves a role at multiple steps in tumorigenesis. The level of cAMP is increased in association with cancer cell formation through activation of AC-stimulatory G protein by mutation. Phosphodiesterases (PDEs) hydrolyze cAMP and cGMP to AMP and GMP. PDEs are composed of 11 families, and each can hydrolyze cAMP and cGMP or both cAMP and cGMP. PDEs perform various roles depending on their location and expression site, and are involved in several diseases, including male erectile dysfunction, pulmonary hypertension, Alzheimer's disease and schizophrenia. PDE11A is the 11th member of the PDE family and is characterized by four splice variants with varying tissue expression and N-terminal regulatory regions. Among tissues, the expression of PDE11A was highest in the prostate, and it was also expressed in hepatic skeletal muscle, pituitary, pancreas and kidney. PDE11A is the first PDE associated with an adrenocortical tumor associated genetic condition. In several studies, three PDE11A mutations have been reported in patients with Cushing syndrome with primary pigmented nodular adrenocortical disease or isolated micronodular adrenocortical disease without other genetic defects. It has been reported that an increase in PDE11A expression affects the proliferation of glioblastoma and worsens patient prognosis. The present mini-review summarizes the location of PDE11A expression, the impact of structural differences and disease relevance.

Microbiota and Transcriptomic Effects of an Essential Oil Blend and Its Delivery Route Compared to an Antibiotic Growth Promoter in Broiler Chickens

This study evaluated the effect of the delivery of a commercial essential oil blend containing the phytonutrients star anise, cinnamon, rosemary, and thyme oil (via different routes) on broiler chickens’ ileal and ceca microbiota and liver transcriptome compared to an antibiotic growth promoter. Eggs were incubated and allocated into three groups: non-injected, in ovo saline, and in ovo essential oil. On day 18 of incubation, 0.2 mL of essential oil in saline (dilution ratio of 2:1) or saline alone was injected into the amnion. At hatch, chicks were assigned to post-hatch treatment combinations: (A) a negative control (corn-wheat-soybean diet), (B) in-feed antibiotics, (C) in-water essential oil (250 mL/1000 L of drinking water), (D) in ovo saline, (E) in ovo essential oil, and (F) in ovo essential oil plus in-water essential oil in eight replicate cages (six birds/cage) and raised for 28 days. On days 21 and 28, one and two birds per cage were slaughtered, respectively, to collect gut content and liver tissues for further analysis. Alpha and beta diversity differed significantly between ileal and ceca samples but not between treatment groups. In-feed antibiotic treatment significantly increased the proportion of specific bacteria in the family Lachnospiraceae while reducing the proportion of bacteria in the genus Christensenellaceae in the ceca, compared to other treatments. Sex-controlled differential expression of genes related to cell signaling and tight junctions were recorded. This study provides data that could guide the use of these feed additives and a foundation for further research.

Molecular Genetic and Genomic Alterations in Cushing's Syndrome and Primary Aldosteronism

The genetic alterations that cause the development of glucocorticoid and/or mineralocorticoid producing benign adrenocortical tumors and hyperplasias have largely been elucidated over the past two decades through advances in genomics. In benign aldosterone-producing adrenocortical tumors and hyperplasias, alteration of intracellular calcium signaling has been found to be significant in aldosterone hypersecretion, with causative defects including those in KCNJ5, ATP1A1, ATP2B3, CACNA1D, CACNA1H, and CLCN2. In benign cortisol-producing adrenocortical tumors and hyperplasias abnormal cyclic adenosine monophosphate-protein kinase A signaling has been found to play a central role in tumorigenesis, with pathogenic variants in GNAS, PRKAR1A, PRKACA, PRKACB, PDE11A, and PDE8B being implicated. The role of this signaling pathway in the development of Cushing's syndrome and adrenocortical tumors was initially discovered through the study of the underlying genetic defects causing the rare multiple endocrine neoplasia syndromes McCune-Albright syndrome and Carney complex with subsequent identification of defects in genes affecting the cyclic adenosine monophosphate-protein kinase A pathway in sporadic tumors. Additionally, germline pathogenic variants in ARMC5, a putative tumor suppressor, were found to be a cause of cortisol-producing primary bilateral macronodular adrenal hyperplasia. This review describes the genetic causes of benign cortisol- and aldosterone-producing adrenocortical tumors.

A phosphodiesterase 11 (Pde11a) knockout mouse expressed functional but reduced Pde11a: Phenotype and impact on adrenocortical function

Phosphodiesterases catalyze the hydrolysis of cyclic nucleotides and maintain physiologic levels of intracellular concentrations of cyclic adenosine and guanosine mono-phosphate (cAMP and cGMP, respectively). Increased cAMP signaling has been associated with adrenocortical tumors and Cushing syndrome. Genetic defects in phosphodiesterase 11A (PDE11A) may lead to increased cAMP signaling and have been found to predispose to the development of adrenocortical, prostate, and testicular tumors. A previously reported Pde11a knockout (Pde11a-/-) mouse line was studied and found to express PDE11A mRNA and protein still, albeit at reduced levels; functional studies in various tissues showed increased cAMP levels and reduced PDE11A activity. Since patients with PDE11A defects and Cushing syndrome have PDE11A haploinsufficiency, it was particularly pertinent to study this hypomorphic mouse line. Indeed, Pde11a-/- mice failed to suppress corticosterone secretion in response to low dose dexamethasone, and in addition exhibited adrenal subcapsular hyperplasia with predominant fetal-like features in the inner adrenal cortex, mimicking other mouse models of increased cAMP signaling in the adrenal cortex. We conclude that a previously reported Pde11a-/- mouse showed continuing expression and function of PDE11A in most tissues. Nevertheless, Pde11a partial inactivation in mice led to an adrenocortical phenotype that was consistent with what we see in patients with PDE11A haploinsufficiency.

Phenotypic and genotypic features of a large kindred with a germline AIP variant

CONTEXT

Acromegaly is usually a sporadic disease, but familial cases occur. Mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene are associated with familial pituitary adenoma predisposition. However, the pathogenicity of some AIP variants remains unclear and additional unknown genes may be involved.

OBJECTIVE

To explore the phenotype and genotype of a large kindred carrying the p.R304Q AIP variant.

METHODS

The family comprised 52 family members at risk of carrying the p.R304Q AIP variant including a case with gigantism and one with acromegaly and several family members with acromegalic features. Nine family members (three trios) underwent exome sequencing to identify putative pathogenic variants.

RESULTS

We identified 31 p.R304Q carriers, and based on two cases with somatotropinomas, the disease penetrance was 6%. We observed physical signs of acromegaly in several family members, which were independent of AIP status. Serum insulin-like growth factor-I (IGF-I) levels in all family members were above the mean for age and sex (IGF-I SDS: +0.6 [CI95% +0.4-0.9], P < .01). Exome analysis identified two candidate genes: PDE11A, known to be associated with the development of adrenal tumours, and ALG14. Ten asymptomatic p.R304Q family members (age >50 years) were screened for the PDE11A and ALG14 variant; both variants were present in five of ten persons.

CONCLUSIONS

This large family adds new information on the p.R304Q AIP variant, and data suggest two new candidate genes could be associated with growth hormone excess.

Adrenocortical tumorigenesis: Lessons from genetics

Advances in genomics over the past two decades have allowed for elucidation of the genetic alterations leading to the development of adrenocortical tumors and/or hyperplasias. These molecular changes were initially discovered through the study of rare familial tumor syndromes such as McCune-Albright Syndrome, Carney complex, Li-Fraumeni syndrome, and Beckwith-Wiedemann syndrome, with the identification of alterations in genes and molecular pathways that subsequently led to the discovery of aberrations in these or related genes and pathways in sporadic tumors. Genetic alterations in GNAS, PRKAR1A, PRKACA, PRKACB, PDE11A, and PDE8B, that lead to aberrant cyclic adenosine monophosphate-protein (cAMP) kinase A signaling, were found to play a major role in the development of benign cortisol-producing adrenocortical tumors and/or hyperplasias, whereas genetic defects in KCNJ5, ATP1A1, ATP2B3, CACNA1D, CACNA1H, and CLCN2 were implicated in the development of benign aldosterone-producing tumors and/or hyperplasias through modification of intracellular calcium signaling. Germline ARMC5 defects were found to cause the development of primary bilateral macronodular adrenocortical hyperplasia with glucocorticoid and/or mineralocorticoid oversecretion. Adrenocortical carcinoma was linked primarily to aberrant p53 signaling and/or Wnt-β-catenin signaling, as well as IGF2 overexpression, with frequent genetic alterations in TP53, ZNRF3, CTNNB1, and 11p15. This review focuses on the genetic underpinnings of benign cortisol- and aldosterone-producing adrenocortical tumors/hyperplasias and adrenocortical carcinoma.

Latin American Study of Hereditary Breast and Ovarian Cancer LACAM: A Genomic Epidemiology Approach

Purpose: Hereditary Breast and Ovarian Cancer (HBOC) syndrome is responsible for ~5-10% of all diagnosed breast and ovarian cancers. Breast cancer is the most common malignancy and the leading cause of cancer-related mortality among women in Latin America (LA). The main objective of this study was to develop a comprehensive understanding of the genomic epidemiology of HBOC throughout the establishment of The Latin American consortium for HBOC-LACAM, consisting of specialists from 5 countries in LA and the description of the genomic results from the first phase of the study. Methods: We have recruited 403 individuals that fulfilled the criteria for HBOC from 11 health institutions of Argentina, Colombia, Guatemala, Mexico and Peru. A pilot cohort of 222 individuals was analyzed by NGS gene panels. One hundred forty-three genes were selected on the basis of their putative role in susceptibility to different hereditary cancers. Libraries were sequenced in MiSeq (Illumina, Inc.) and PGM (Ion Torrent-Thermo Fisher Scientific) platforms. Results: The overall prevalence of pathogenic variants was 17% (38/222); the distribution spanned 14 genes and varied by country. The highest relative prevalence of pathogenic variants was found in patients from Argentina (25%, 14/57), followed by Mexico (18%, 12/68), Guatemala (16%, 3/19), and Colombia (13%, 10/78). Pathogenic variants were found in BRCA1 (20%) and BRCA2 (29%) genes. Pathogenic variants were found in other 12 genes, including high and moderate risk genes such as MSH2, MSH6, MUTYH, and PALB2. Additional pathogenic variants were found in HBOC unrelated genes such as DCLRE1C, WRN, PDE11A, and PDGFB. Conclusion: In this first phase of the project, we recruited 403 individuals and evaluated the germline genetic alterations in an initial cohort of 222 patients among 4 countries. Our data show for the first time in LA the distribution of pathogenic variants in a broad set of cancer susceptibility genes in HBOC. Even though we used extended gene panels, there was still a high proportion of patients without any detectable pathogenic variant, which emphasizes the larger, unexplored genetic nature of the disease in these populations.

A Novel Flavonoid Kushenol Z from Sophora flavescens Mediates mTOR Pathway by Inhibiting Phosphodiesterase and Akt Activity to Induce Apoptosis in Non-Small-Cell Lung Cancer Cells

The roots of Sophora flavescens (SF) are clinically used as a traditional Chinese medicine for the treatment of various lung diseases. In this study, we investigated the mechanism by which SF inhibits proliferation and induces apoptosis in non-small-cell lung cancer (NSCLC) cells. A new compound, kushenol Z (KZ), and 14 known flavonoids were isolated from SF. KZ, sophoraflavanone G, and kushenol A demonstrated potent cytotoxicity against NSCLC cells in a dose- and time-dependent manner; KZ showed a wide therapeutic window. We also found that KZ induced NSCLC cell apoptosis by increasing the Bax/Bcl-2 ratio and by activating caspase-3 and caspase-9 leading to mitochondrial apoptosis, and upregulated CHOP and activatedcaspase-7 and caspase-12, which triggered the endoplasmic reticulum stress pathway. After KZ treatment, we observed cAMP accumulation, which reflected the inhibition of cAMP-phosphodiesterase (PDE), along with the increase in PKA activity; additionally, phospho-p70 S6 kinase was downregulated. KZ also attenuated the phosphorylation of Akt and PRAS40, which was partially rescued by an Akt activator. This suggested that KZ mediated the antiproliferative activity in NSCLC cells by inhibiting the mTOR pathway through the inhibition of cAMP-PDE and Akt. These findings suggested that KZ may be used as a promising cAMP-PDE and Akt inhibitor in targeted chemotherapeutic drug development.

Therapeutic opportunities in colon cancer: Focus on phosphodiesterase inhibitors

Despite novel technologies, colon cancer remains undiagnosed and 25% of patients are diagnosed with metastatic colon cancer. Resistant to chemotherapeutic agents is one of the major problems associated with treating colon cancer which creates the need to develop novel agents targeting towards newer targets. A phosphodiesterase is a group of isoenzyme, which, hydrolyze cyclic nucleotides and thereby lowers intracellular levels of cAMP and cGMP leading to tumorigenic effects. Many in vitro and in vivo studies have confirmed increased PDE expression in different types of cancers including colon cancer. cAMP-specific PDE inhibitors increase intracellular cAMP that leads to activation of effector molecules-cAMP-dependent protein kinase A, exchange protein activated by cAMP and cAMP gated ion channels. These molecules regulate cellular responses and exert its anticancer role through different mechanisms including apoptosis, inhibition of angiogenesis, upregulating tumor suppressor genes and suppressing oncogenes. On the other hand, cGMP specific PDE inhibitors exhibit anticancer effects through cGMP dependent protein kinase and cGMP dependent cation channels. Elevation in cGMP works through activation of caspases, suppression of Wnt/b-catenin pathway and TCF transcription leading to inhibition of CDK and survivin. These studies point out towards the fact that PDE inhibition is associated with anti-proliferative, anti-apoptotic and anti-angiogenic pathways involved in its anticancer effects in colon cancer. Thus, inhibition of PDE enzymes can be used as a novel approach to treat colon cancer. This review will focus on cAMP and cGMP signaling pathways leading to tumorigenesis and the use of PDE inhibitors in colon cancer.

An update on adrenal endocrinology: significant discoveries in the last 10 years and where the field is heading in the next decade

The last 10 years have produced an amazing number of significant discoveries in the field of adrenal endocrinology. The development of the adrenal gland was linked to specific molecules. Cortisol-producing lesions were associated mostly with defects of the cyclic AMP (cAMP) signaling pathway, whereas aldosterone-producing lesions were found to be the result of defects in aldosterone biosynthesis or the potassium channel KCNJ5 and related molecules. Macronodular adrenal hyperplasia was linked to ARMC5 defects and new genes were found to be involved in adrenocortical cancer (ACC). The succinate dehydrogenase (SDH) enzyme was proven to be the most important molecular pathway involved in pheochromocytomas, along with several other genes. Adrenomedullary tumors are now largely molecularly elucidated. Unfortunately, most of these important discoveries have yet to produce new therapeutic tools for our patients with adrenal diseases: ACC in its advanced stages remains largely an untreatable disorder and malignant pheochromocytomas are equally hard to treat. Thus, the challenge for the next 10 years is to translate the important discoveries of the previous decade into substantial advances in the treatment of adrenal disorders and tumors.

Comprehensive Analysis of Germline Variants in Mexican Patients with Hereditary Breast and Ovarian Cancer Susceptibility

Hereditary breast and ovarian cancer syndrome (HBOC) represents 5⁻10% of all patients with breast cancer and is associated with high-risk pathogenic alleles in BRCA1/2 genes, but only for 25% of cases. We aimed to find new pathogenic alleles in a panel of 143 cancer-predisposing genes in 300 Mexican cancer patients with suspicion of HBOC and 27 high-risk patients with a severe family history of cancer, using massive parallel sequencing. We found pathogenic variants in 23 genes, including BRCA1/2. In the group of cancer patients 15% (46/300) had a pathogenic variant; 11% (33/300) harbored variants with unknown clinical significance (VUS) and 74% (221/300) were negative. The high-risk group had 22% (6/27) of patients with pathogenic variants, 4% (1/27) had VUS and 74% (20/27) were negative. The most recurrent mutations were the Mexican founder deletion of exons 9-12 and the variant p.G228fs in BRCA1, each found in 5 of 17 patients with alterations in this gene. Rare VUS with potential impact at the protein level were found in 21 genes. Our results show for the first time in the Mexican population a higher contribution of pathogenic alleles in other susceptibility cancer genes (54%) than in BRCA1/2 (46%), highlighting the high locus heterogeneity of HBOC and the necessity of expanding genetic tests for this disease to include broader gene panels.

Inhibitors of phosphodiesterase as cancer therapeutics

Phosphodiesterases (PDEs) are a class of enzymes that hydrolyze cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) which is involved in many physiological processes including visual transduction, cell proliferation and differentiation, cell-cycle regulation, gene expression, inflammation, apoptosis, and metabolic function. PDEs are composed of 11 different families and each family contains different subtypes. The distribution, expression, regulation mode and sensitivity to inhibitors of each subtype are different, and they are involved in cancer, inflammation, asthma, depression, erectile dysfunction and other pathological processes of development. A large number of studies have shown that PDEs play an important role in the development of tumors by affecting the intracellular level of cAMP and/or cGMP and PDEs could become diagnostic markers or therapeutic targets. This review will give a brief overview of the expression and regulation of PDE families in the process of tumorigenesis and their anti-tumor inhibitors, which may guide the design of novel therapeutic drugs targeting PDEs for anticancer agent.

A Role for Phosphodiesterase 11A (PDE11A) in the Formation of Social Memories and the Stabilization of Mood

The most recently discovered 3',5'-cyclic nucleotide phosphodiesterase family is the Phosphodiesterase 11 (PDE11) family, which is encoded by a single gene PDE11A. PDE11A is a dual-specific PDE, breaking down both cAMP and cGMP. There are four PDE11A splice variants (PDE11A1-4) with distinct tissue expression profiles and unique N-terminal regulatory regions, suggesting that each isoform could be individually targeted with a small molecule or biologic. PDE11A4 is the PDE11A isoform expressed in brain and is found in the hippocampal formation of humans and rodents. Studies in rodents show that PDE11A4 mRNA expression in brain is, in fact, restricted to the hippocampal formation (CA1, possibly CA2, subiculum, and the adjacently connected amygdalohippocampal area). Within the hippocampal formation of rodents, PDE11A4 protein is expressed in neurons but not astrocytes, with a distribution across nuclear, cytoplasmic, and membrane compartments. This subcellular localization of PDE11A4 is altered in response to social experience in mouse, and in vitro studies show the compartmentalization of PDE11A4 is controlled, at least in part, by homodimerization and N-terminal phosphorylation. PDE11A4 expression dramatically increases in the hippocampus with age in the rodent hippocampus, from early postnatal life to late aging, suggesting PDE11A4 function may evolve across the lifespan. Interestingly, PDE11A4 protein shows a three to tenfold enrichment in the rodent ventral hippocampal formation (VHIPP; a.k.a. anterior in primates) versus dorsal hippocampal formation (DHIPP). Consistent with this enrichment in VHIPP, studies in knockout mice show that PDE11A regulates the formation of social memories and the stabilization of mood and is a critical mechanism by which social experience feeds back to modify the brain and subsequent social behaviors. PDE11A4 likely controls behavior by regulating hippocampal glutamatergic, oxytocin, and cytokine signaling, as well as protein translation. Given its unique tissue distribution and relatively selective effects on behavior, PDE11A may represent a novel therapeutic target for neuropsychiatric, neurodevelopmental, or age-related disorders. Therapeutically targeting PDE11A4 may be a way to selectively restore aberrant cyclic nucleotide signaling in the hippocampal formation while leaving the rest of the brain and periphery untouched, thus, relieving deficits while avoiding unwanted side effects.

Phosphodiesterase type 5 and cancers: progress and challenges

Cancers are an extraordinarily heterogeneous collection of diseases with distinct genetic profiles and biological features that directly influence response patterns to various treatment strategies as well as clinical outcomes. Nevertheless, our growing understanding of cancer cell biology and tumor progression is gradually leading towards rational, tailored medical treatments designed to destroy cancer cells by exploiting the unique cellular pathways that distinguish them from normal healthy counterparts. Recently, inhibition of the activity of phosphodiesterase type 5 (PDE5) is emerging as a promising approach to restore normal intracellular cyclic guanosine monophosphate (cGMP) signalling, and thereby resulting into the activation of various downstream molecules to inhibit proliferation, motility and invasion of certain cancer cells. In this review, we present an overview of the experimental and clinical evidences highlighting the role of PDE5 in the pathogenesis and prevention of various malignancies. Current data are still not sufficient to draw conclusive statements for cancer patient management, but could provide further rational for testing PDE5-targeting drugs as anticancer agents in clinical settings.

Phosphodiesterase sequence variants may predispose to prostate cancer

We hypothesized that mutations that inactivate phosphodiesterase (PDE) activity and lead to increased cAMP and cyclic guanosine monophosphate levels may be associated with prostate cancer (PCa). We sequenced the entire PDE coding sequences in the DNA of 16 biopsy samples from PCa patients. Novel mutations were confirmed in the somatic or germline state by Sanger sequencing. Data were then compared to the 1000 Genome Project. PDE, CREB and pCREB protein expression was also studied in all samples, in both normal and abnormal tissue, by immunofluorescence. We identified three previously described PDE sequence variants that were significantly more frequent in PCa. Four novel sequence variations, one each in the PDE4B,PDE6C, PDE7B and PDE10A genes, respectively, were also found in the PCa samples. Interestingly, PDE10A and PDE4B novel variants that were present in 19 and 6% of the patients were found in the tumor tissue only. In patients carrying PDE defects, there was pCREB accumulation (P<0.001), and an increase of the pCREB:CREB ratio (patients 0.97±0.03; controls 0.52±0.03; P-value <0.001) by immunohistochemical analysis. We conclude that PDE sequence variants may play a role in the predisposition and/or progression to PCa at the germline and/or somatic state respectively.

McCune Albright syndrome and bilateral adrenal hyperplasia: the GNAS mutation may only be present in adrenal tissue

OBJECTIVE

Corticotropin (ACTH)-independent hypercortisolism due to bilateral adrenocortical hyperplasia (BAH) in infancy is an extremely rare condition that is often caused by McCune Albright syndrome (MAS). MAS is caused by an activating mutation of the GNAS gene which leads to increased cyclic (c) adenosine monophosphate (AMP) signaling. Most forms of BAH are linked to increased cAMP signaling. We report the case of an infant with MAS who had BAH.

METHODS

Genomic DNA fragments from blood and adrenal tissue encompassing regions (exons 8 and 9) with the hot spot activating missense GNAS mutations were amplified by classical bidirectional Sanger sequencing.

RESULTS

The infant was found to carry the most common GNAS mutation, in exon 8 (c.602G >A, p. R201H), only in her adrenocortical tissue, despite extensive skin and other findings.

CONCLUSIONS

We conclude that infants with MAS, despite absence of the GNAS activating mutation in blood, may still have significant clinical findings, including ACTH-independent hypercortisolism. Molecular confirmation of the diagnosis should be sought at the tissue level in these patients.

Is IGSF1 involved in human pituitary tumor formation?

IGSF1 is a membrane glycoprotein highly expressed in the anterior pituitary. Pathogenic mutations in the IGSF1 gene (on Xq26.2) are associated with X-linked central hypothyroidism and testicular enlargement in males. In this study, we tested the hypothesis that IGSF1 is involved in the development of pituitary tumors, especially those that produce growth hormone (GH). IGSF1 was sequenced in 21 patients with gigantism or acromegaly and 92 healthy individuals. Expression studies with a candidate pathogenic IGSF1 variant were carried out in transfected cells and immunohistochemistry for IGSF1 was performed in the sections of GH-producing adenomas, familial somatomammotroph hyperplasia, and in normal pituitary. We identified the sequence variant p.N604T, which in silico analysis suggested could affect IGSF1 function, in two male patients and one female with somatomammotroph hyperplasia from the same family. Of 60 female controls, two carried the same variant and seven were heterozygous for other variants. Immunohistochemistry showed increased IGSF1 staining in the GH-producing tumor from the patient with the IGSF1 p.N604T variant compared with a GH-producing adenoma from a patient negative for any IGSF1 variants and with normal control pituitary tissue. The IGSF1 gene appears polymorphic in the general population. A potentially pathogenic variant identified in the germline of three patients with gigantism from the same family (segregating with the disease) was also detected in two healthy female controls. Variations in IGSF1 expression in pituitary tissue in patients with or without IGSF1 germline mutations point to the need for further studies of IGSF1 action in pituitary adenoma formation.

p54nrb/NONO regulates cyclic AMP-dependent glucocorticoid production by modulating phosphodiesterase mRNA splicing and degradation

Glucocorticoid production in the adrenal cortex is activated in response to an increase in cyclic AMP (cAMP) signaling. The nuclear protein p54(nrb)/NONO belongs to the Drosophila behavior/human splicing (DBHS) family and has been implicated in several nuclear processes, including transcription, splicing, and RNA export. We previously identified p54(nrb)/NONO as a component of a protein complex that regulates the transcription of CYP17A1, a gene required for glucocorticoid production. Based on the multiple mechanisms by which p54(nrb)/NONO has been shown to control gene expression and the ability of the protein to be recruited to the CYP17A1 promoter, we sought to further define the molecular mechanism by which p54(nrb)/NONO confers optimal cortisol production. We show here that silencing p54(nrb)/NONO expression in H295R human adrenocortical cells decreases the ability of the cells to increase intracellular cAMP production and subsequent cortisol biosynthesis in response to adrenocorticotropin hormone (ACTH) stimulation. Interestingly, the expression of multiple phosphodiesterase (PDE) isoforms, including PDE2A, PDE3A, PDE3B, PDE4A, PDE4D, and PDE11A, was induced in p54(nrb)/NONO knockdown cells. Investigation of the mechanism by which silencing of p54(nrb)/NONO led to increased expression of select PDE isoforms revealed that p54(nrb)/NONO regulates the splicing of a subset of PDE isoforms. Importantly, we also identify a role for p54(nrb)/NONO in regulating the stability of PDE transcripts by facilitating the interaction between the exoribonuclease XRN2 and select PDE transcripts. In summary, we report that p54(nrb)/NONO modulates cAMP-dependent signaling, and ultimately cAMP-stimulated glucocorticoid biosynthesis by regulating the splicing and degradation of PDE transcripts.

Phosphodiesterases and adrenal Cushing in mice and humans

The majority of benign adrenal cortex lesions leading to Cushing syndrome are associated to one or another abnormality of the cAMP/cGMP-phosphodiesterase signaling pathway. Phosphodiesterases (PDEs) are key regulatory enzymes of intracellular cAMP/cGMP levels. These second messengers play important regulatory roles in controlling steroidogenesis in the adrenal. Disruption of PDEs has been associated with a number of adrenal diseases. Specifically, genetic mutations have been associated with benign adrenal lesions, leading to Cushing syndrome and/or related adrenal hyperplasias. A Genome Wide Association study, in 2006, led to the identification of mutations in 2 PDE genes: PDE8B and PDE11A; mutations in these 2 genes modulate steroidogenesis. Further human studies have identified PDE2 as also directly regulating steroidogenesis. PDE2 decreases aldosterone production. This review focuses on the most recent knowledge we have gained on PDEs and their association with adrenal steroidogenesis and altered function, through analysis of patient cohorts and what we have learned from mouse studies.

Cyclic nucleotide phosphodiesterases: important signaling modulators and therapeutic targets

By catalyzing hydrolysis of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), cyclic nucleotide phosphodiesterases are critical regulators of their intracellular concentrations and their biological effects. As these intracellular second messengers control many cellular homeostatic processes, dysregulation of their signals and signaling pathways initiate or modulate pathophysiological pathways related to various disease states, including erectile dysfunction, pulmonary hypertension, acute refractory cardiac failure, intermittent claudication, chronic obstructive pulmonary disease, and psoriasis. Alterations in expression of PDEs and PDE-gene mutations (especially mutations in PDE6, PDE8B, PDE11A, and PDE4) have been implicated in various diseases and cancer pathologies. PDEs also play important role in formation and function of multimolecular signaling/regulatory complexes, called signalosomes. At specific intracellular locations, individual PDEs, together with pathway-specific signaling molecules, regulators, and effectors, are incorporated into specific signalosomes, where they facilitate and regulate compartmentalization of cyclic nucleotide signaling pathways and specific cellular functions. Currently, only a limited number of PDE inhibitors (PDE3, PDE4, PDE5 inhibitors) are used in clinical practice. Future paths to novel drug discovery include the crystal structure-based design approach, which has resulted in generation of more effective family-selective inhibitors, as well as burgeoning development of strategies to alter compartmentalized cyclic nucleotide signaling pathways by selectively targeting individual PDEs and their signalosome partners.

Macronodular adrenal hyperplasia due to mutations in an armadillo repeat containing 5 (ARMC5) gene: a clinical and genetic investigation

CONTEXT

Inactivating germline mutations of the probable tumor suppressor gene, armadillo repeat containing 5 (ARMC5), have recently been identified as a genetic cause of macronodular adrenal hyperplasia (MAH).

OBJECTIVE

We searched for ARMC5 mutations in a large cohort of patients with MAH. The clinical phenotype of patients with and without ARMC5 mutations was compared.

METHODS

Blood DNA from 34 MAH patients was genotyped using Sanger sequencing. Diurnal serum cortisol measurements, plasma ACTH levels, urinary steroids, 6-day Liddle's test, adrenal computed tomography, and weight of adrenal glands at adrenalectomy were assessed.

RESULTS

Germline ARMC5 mutations were found in 15 of 34 patients (44.1%). In silico analysis of the mutations indicated that seven (20.6%) predicted major implications for gene function. Late-night cortisol levels were higher in patients with ARMC5-damaging mutations compared with those without and/or with nonpathogenic mutations (14.5 ± 5.6 vs 6.7 ± 4.3, P < .001). All patients carrying a pathogenic ARMC5 mutation had clinical Cushing's syndrome (seven of seven, 100%) compared with 14 of 27 (52%) of those without or with mutations that were predicted to be benign (P = .029). Repeated-measures analysis showed overall higher urinary 17-hydroxycorticosteroids and free cortisol values in the patients with ARMC5-damaging mutations during the 6-day Liddle's test (P = .0002).

CONCLUSIONS

ARMC5 mutations are implicated in clinically severe Cushing's syndrome associated with MAH. Knowledge of a patient's ARMC5 status has important clinical implications for the diagnosis of Cushing's syndrome and genetic counseling of patients and their families.

Clinical and molecular genetics of the phosphodiesterases (PDEs)

Cyclic nucleotide phosphodiesterases (PDEs) are enzymes that have the unique function of terminating cyclic nucleotide signaling by catalyzing the hydrolysis of cAMP and GMP. They are critical regulators of the intracellular concentrations of cAMP and cGMP as well as of their signaling pathways and downstream biological effects. PDEs have been exploited pharmacologically for more than half a century, and some of the most successful drugs worldwide today affect PDE function. Recently, mutations in PDE genes have been identified as causative of certain human genetic diseases; even more recently, functional variants of PDE genes have been suggested to play a potential role in predisposition to tumors and/or cancer, especially in cAMP-sensitive tissues. Mouse models have been developed that point to wide developmental effects of PDEs from heart function to reproduction, to tumors, and beyond. This review brings together knowledge from a variety of disciplines (biochemistry and pharmacology, oncology, endocrinology, and reproductive sciences) with emphasis on recent research on PDEs, how PDEs affect cAMP and cGMP signaling in health and disease, and what pharmacological exploitations of PDEs may be useful in modulating cyclic nucleotide signaling in a way that prevents or treats certain human diseases.

cAMP/PKA signaling defects in tumors: genetics and tissue-specific pluripotential cell-derived lesions in human and mouse

In the last few years, bench and clinical studies led to significant new insight into how cyclic adenosine monophosphate (cAMP) signaling, the molecular pathway that had been identified in the early 2000s as the one involved in most benign cortisol-producing adrenal hyperplasias, affects adrenocortical growth and development, as well as tumor formation. A major discovery was the identification of tissue-specific pluripotential cells (TSPCs) as the culprit behind tumor formation not only in the adrenal, but also in bone. Discoveries in animal studies complemented a number of clinical observations in patients. Gene identification continued in parallel with mouse and other studies on the cAMP signaling and other pathways.

Research and development in the molecular genetics of pituitary adenomas and related tumors

Interview by Rona Williamson Constantine A Stratakis received his MD and Doctor of Medical Sciences degrees from the University of Athens (Greece) in 1989 and 1994, respectively; he did predoctoral work at the Unit of Endocrinology, Department of Experimental Pharmacology of the same University and at Hospital Cochin (Paris, France), before joining the Developmental Endocrinology Branch of the then National Institute of Child Health & Human Development (NICHD) at the NIH (MD, USA). He continued his postgraduate medical education at Georgetown University Medical School (DC, USA), where he finished a residency in Pediatrics and two fellowships, in Pediatric Endocrinology, followed by Medical Genetics and Clinical Dysmorphology (in a joint program with the then newly founded National Center for Genomic Research, now NHGRI). Dr Stratakis is Board-certified in Pediatrics, Pediatric Endocrinology and Medical Genetics; after a brief stint as faculty at Georgetown University Department of Pediatrics and the Fairfax Children's Hospital, he joined the Developmental Endocrinology Branch, NICHD, NIH as a Unit Chief in 1996; he continued there as a Senior Investigator and Chief of the Section on Genetics & Endocrinology. Since 2002, he is the Director of the Pediatric Endocrinology Training Fellowship and from 2007 to 2011, he served as Branch Chief and then Head of the Program on Developmental Endocrinology & Genetics (PDEGEN), the largest Department of the Intramural Clinical Research program of NICHD at the NIH Clinical Center. He is the author of more than 400 publications, and has served as a regular Reviewer in more than 100 journals, including Science, Nature Genetics, New England Journal of Medicine and others; he was Editor-in-Chief of the Journal of Endocrine Genetics (2000-2005) and is currently serving on the Editorial Boards of several journals; as of 1 January 2010, Dr Stratakis is a Deputy Editor of the Journal of Clinical Endocrinology & Metabolism, the leading journal in endocrinology. Dr Stratakis has been the recipient of the 1999 Pharmacia-Endocrine Society Award for Excellence in Published Clinical Research, three NIH Merit Awards and other honors, and has been named Visiting Professor in academic centers around the world. He was awarded the 2009 Ernst Oppenheimer Award of the Endocrine Society. Dr Stratakis has been the Scientific Director of the Eunice Kennedy Shriver National Institute of Child Health & Human Development since 2011.

Phosphodiesterase 11A (PDE11A) gene defects in patients with acth-independent macronodular adrenal hyperplasia (AIMAH): functional variants may contribute to genetic susceptibility of bilateral adrenal tumors

CONTEXT

Phosphodiesterases (PDEs) are key regulatory enzymes of intracellular cAMP levels. PDE11A function has been linked to predisposition to adrenocortical tumors.

OBJECTIVE

The aim of the study was to study the PDE11A gene in a large cohort of patients with ACTH-independent macronodular adrenal hyperplasia (AIMAH) and in control subjects.

DESIGN

The PDE11A entire coding region was sequenced in 46 patients with AIMAH and 192 controls. Two variants found in AIMAH patients were transiently expressed in HEK 293 and adrenocortical H295R cells for further functional studies.

RESULTS

The frequency of all PDE11A variants was significantly higher among patients with AIMAH (28%) compared to controls (7.2%) (P = 5 × 10(-5)). Transfection of the two PDE11A variants found in AIMAH patients only (D609N or M878V) showed that cAMP levels were higher, after forskolin stimulation, in cells transfected with the PDE11A mutants, compared to cells transfected with the wild-type PDE11A in HEK 293 cells (P < 0.05). Moreover, transfection with mutants PDE11A increased transcriptional activity of a cAMP-response element reporter construct compared to wild-type PDE11A in HEK 293 cells (P < 0.0004 for D609N and P < 0.003 for M878V) and in the adrenocortical H295R cells (P < 0.05 for D609N and M878V). In addition, analysis of cAMP levels in intact living culture cells by fluorescence resonance energy transfer probes showed increased cAMP in forskolin-treated cells transfected with PDE11A variants compared with wild-type PDE11A (P < 0.05).

CONCLUSION

We conclude that PDE11A genetic variants may increase predisposition to AIMAH.

Cyclic AMP, protein kinase A, and phosphodiesterases: proceedings of an international workshop

Cyclic nucleotides cAMP and cGMP are part of almost all major cellular signaling pathways. Phosphodiesterases (PDEs) are enzymes that regulate the intracellular levels of cAMP and cGMP. Protein kinase A or cAMP-dependent protein kinase mediates most cAMP effects in the cell. Over the last 25 years, various components of this group of molecules have been involved in human diseases, both genetic and acquired. Lately, the PDEs attract more attention. The pharmacological exploitation of the PDE's ability to regulate cGMP and cAMP, and through them, a variety of signaling pathways, has led to a number of new drugs for diverse applications from the treatment of erectile dysfunction to heart failure, asthma, and chronic obstructive pulmonary disease. We present the abstracts (available online) and selected articles from the proceedings of a meeting that took place at the National Institutes of Health (NIH), Bethesda, MD, June 8-10, 2011.

Identification of novel genetic variants in phosphodiesterase 8B (PDE8B), a cAMP-specific phosphodiesterase highly expressed in the adrenal cortex, in a cohort of patients with adrenal tumours

BACKGROUND

Genetic aberrations in various components of cAMP signalling pathway predispose to endocrine tumours. Mutations in the phosphodiesterases (PDEs) are involved in the predisposition to adrenocortical neoplastic conditions.

OBJECTIVE

To screen for genetic variations in PDE8B among patients with different types of adrenocortical tumours.

DESIGN AND SUBJECTS

This is a case-control study followed by functional analyses. Two hundred and sixteen unrelated patients with different types of adrenocortical tumours and 192 healthy control individuals participated in the study.

METHODS

Bidirectional Sanger sequencing, in vitro cell line transfection and in silico modelling are used in this study.

RESULTS

Nine different PDE8B sequence changes, six novel and three previously reported, were identified in our patients and controls. Two of the variations, seen only in the patient group, showed significant potential to impair protein function, both in vitro and in silico.

CONCLUSION

PDE8B is another PDE gene in which variations may contribute to predisposition of adrenocortical tumours.

Identification of biologically active PDE11-selective inhibitors using a yeast-based high-throughput screen

The biological roles of cyclic nucleotide phosphodiesterase 11 (PDE11) enzymes are poorly understood, in part due to the lack of selective inhibitors. To address the need for such compounds, we completed an ~200,000 compound high-throughput screen (HTS) for PDE11 inhibitors using a yeast-based growth assay, and identified 4 potent and selective PDE11 inhibitors. One compound, along with two structural analogs, elevates cAMP and cortisol levels in human adrenocortical cells, consistent with gene association studies that link PDE11 activity to adrenal function. As such, these compounds can immediately serve as chemical tools to study PDE11 function in cell culture, and as leads to develop therapeutics for the treatment of adrenal insufficiencies. Our results further validate this yeast-based HTS platform for the discovery of potent, selective, and biologically active PDE inhibitors.

Phosphodiesterase function and endocrine cells: links to human disease and roles in tumor development and treatment

Phosphodiesterases (PDEs) are enzymes that regulate the intracellular levels of cyclic adenosine monophosphate and cyclic guanosine monophosphate, and, consequently, exhibit a central role in multiple cellular functions. The pharmacological exploitation of the ability of PDEs to regulate specific pathways has led to the discovery of drugs with selective action against specific PDE isoforms. Considerable attention has been given to the development of selective PDE inhibitors, especially after the therapeutic success of PDE5 inhibitors in the treatment of erectile dysfunction. Several associations between PDE genes and genetic diseases have been described, and more recently PDE11A and PDE8B have been implicated in predisposition to tumor formation. This review focuses on the possible function of PDEs in a variety of tumors, primarily in endocrine glands, both in tumor predisposition and as potential therapeutic targets.