Differential expression of phosphodiesterase 3B in cancers of the breast.

Breast cancer affects women at relatively high frequency (1). We mined published microarray datasets (2, 3) to determine in an unbiased fashion and at the systems level genes most differentially expressed in the primary tumors of patients with breast cancer. We report here significant differential expression of the gene encoding phosphodiesterase 3B, PDE3B, when comparing primary tumors of the breast to the tissue of origin, the normal breast. PDE3B mRNA was present at significantly lower quantities in tumors of the breast as compared to normal breast tissue. Analysis of human survival data revealed that expression of PDE3B in primary tumors of the breast was correlated with distant metastasis-free survival in patients with basal subtype cancer, demonstrating a relationship between primary tumor expression of a differentially expressed gene and patient survival outcomes influenced by PAM50 molecular subtype. PDE3B may be of relevance to initiation, maintenance or progression of cancers of the female breast.

Mechanistic Insights on Cytotoxicity of KOLR by targeting Signaling Complexes of phosphodiesterase 3B and Rap guanine nucleotide exchange factor 3

Background Protein signaling complexes play important roles in prevention of several cancer types and can be used for development of targeted therapy. The roles of signaling complexes of phosphodiesterase 3B (PDE3B) and Rap guanine nucleotide exchange factor 3 (RAPGEF3), which are two important enzymes of cyclic adenosine monophosphate (cAMP) metabolism, in cancer have not been fully explored. Methods The natural product Kaempferol-3-O-(3′′,4′′-di-E-p-coumaroyl)-α-L-rhamnopyranoside designated as KOLR was extracted from Cinnamomum pauciflorum Nees leaves using reverse phase chromatography, high-resolution mass spectrometry, and nuclear magnetic resonance spectroscopy. The antitumor effect of KOLR was analyzed by multiple cell proliferation and metastasis experiments. The PDE3B/RAPGEF3 complex was found to be the target of KOLR through mRNA sequencing, Co-Immunoprecipitation assay, gene knock-down, gene mutation of drug-resistance cell line, and molecular docking. In vivo studies have shown that KOLR has the same antitumor mechanism. Results KOLR exhibited cytotoxic effects against selected cancer cells, except for AsPC-1 pancreatic cancer cell line. KOLR stabilized PDE3B/RAPGEF3 signaling complex thus inhibiting AKT phosphorylation and Rap-1 activation. Notably, mutation of RAPGEF3 G557A inhibited effect of KOLR on stabilizing PDE3B/RAPGEF3 complex in AsPC-1 cells. Furthermore, downregulation of PDE3B expression inhibited cytotoxic effect of KOLR on tumor cells. Downregulation of RAPGEF3 and Rap-1 expression promoted apoptosis of tumor cells and inhibited tumor metastasis. PDE3B inhibits activity of RAPGEF3 and activation of downstream signaling pathway. Conclusion The findings of this study show that KOLR could stabilize PDE3B/RAPGEF3 signaling complex to play an anti-tumor role and the PDE3B/RAPGEF3 complex is a potential therapeutic cancer target.

In Vitro Inhibition of Phosphodiesterase 3B (PDE 3B) by Anthocyanin-Rich Fruit Juice Extracts and Selected Anthocyanins

Phosphodiesterases (PDEs) are essential enzymes for the regulation of pathways mediated by cyclic adenosine monophosphate (cAMP). Secondary plant compounds like anthocyanins (ACs) can inhibit PDE activity and, consequently, may be beneficial for lipid metabolism. This study investigated 18 AC-rich juice extracts and pure reference compounds from red fruits for potential inhibitory effects on PDE 3B activity. Extracts were obtained through adsorption on Amberlite® XAD 7 resin. Based on this screening, the chokeberry, blueberry, pomegranate, and cranberry extracts were active, with half maximal inhibitory concentrations (IC50) ranging from 163 ± 3 µg/mL to 180 ± 3 µg/mL. The ACs in these extracts, peonidin-3-glucoside and cyanidin-3-arabinoside, were the most active single compounds (IC50 = 56 ± 20 µg/mL, 108 ± 6 µg/mL). All extracts comprised high amounts of phenolic compounds, as determined by the Folin–Ciocalteu assay, ranging from 39.8 ± 1.5 to 73.5 ± 4.8 g gallic acid equivalents (GAE)/100 g extract. Pomegranate and chokeberry extracts exhibited the largest amounts of polyphenols (72.3 ± 0.7 g GAE/100 g, 70.6 ± 4.1 g GAE/100 g, respectively). Overall, our results showed that fruit juice extracts and their ACs can inhibit PDE activity. Any potential health benefits in vivo will be investigated in the future.

Influence of Aging and Menstrual Status on Subcutaneous Fat Cell Lipolysis

Context Aging is accompanied by inhibited fat cell mobilization of fatty acids through lipolysis, which may contribute to decreased energy expenditure in elderly subjects. However, the influence of menstrual status is unknown. Objective To investigate the role of menstrual status on changes in lipolysis induced by aging. Design A longitudinal investigation with a mean 13-year interval. Setting Ambulatory study at a clinical academic unit. Participants Eighty-two continuously recruited women between 24 and 62 years of age and with body mass index 21 to 48 kg/m2 at first examination. Twenty-nine women continued to have normal menstruation, 42 developed irregular menstruation/menopause, and 11 had a perimenstrual/menopausal phenotype already at the first examination. Main outcome measure Lipolysis measured as glycerol release from isolated subcutaneous fat cells incubated in vitro. Results On average, body weight/body fat mass levels did not change over time. In all 3 groups, aging was associated with a similar decrease in spontaneous (basal) and catecholamine-stimulated lipolysis. The latter was due to decreased signal transduction through stimulatory beta adrenoceptors and increased alpha-2-adrenoceptor–mediated antilipolytic effects. Gene microarray data from adipose tissue at baseline and follow-up (n = 53) showed that a limited set of lipolysis-linked genes, including phosphodiesterase-3B, were altered over time, but this was independent of menstrual status. Fat cell size also decreased during aging, but this could not explain the decrease in lipolysis. Conclusions In women, the rate of fat cell lipolysis decreases during aging due to multiple alterations in spontaneous (basal) and catecholamine-induced lipolysis. This is independent of changes in menstrual status or fat cell size.

Hypothalamic PDE3B deficiency alters body weight and glucose homeostasis in mouse

Pharmacological studies have suggested hypothalamic phosphodiesterase-3B to mediate leptin and insulin action in regulation of energy homeostasis. Whereas Pde3b-null mice show altered energy homeostasis, it is unknown whether this is due to ablation of Pde3b in the hypothalamus. Thus, to address the functional significance of hypothalamic phosphodiesterase-3B, we used Pde3b flox/flox and Nkx2.1-Cre mice to generate Pde3b Nkx2.1KD mice that showed 50% reduction of phosphodiesterase-3B in the hypothalamus. To determine the effect of partial ablation of phosphodiesterase-3B in the hypothalamus on energy and glucose homeostasis, males and females were subjected to either a low- or high-fat diet for 19–21 weeks. Only female but not male Pde3b Nkx2.1KD mice on the low-fat diet showed increased body weight from 13 weeks onward with increased food intake, decreased fat pad weights and hypoleptinemia. Glucose tolerance was improved in high-fat diet-fed male Pde3b Nkx2.1KD mice in association with decreased phosphoenolpyruvate carboxykinase-1 and glucose-6-phosphatase mRNA levels in the liver. Also, insulin sensitivity was increased in male Pde3b Nkx2.1KD mice on the low-fat diet. Changes in body weight or in glucose homeostasis were not associated with any alteration in hypothalamic proopiomelanocortin, neuropepide Y and agouti-related peptide mRNA levels. These results suggest that partial loss of phosphodiesterase-3B in the hypothalamus produces a sex-specific response in body weight and glucose homeostasis, and support a role, at least in part, for hypothalamic phosphodiesterase-3B in regulation of energy and glucose homeostasis in mice.