Choline-releasing glycerophosphodiesterase EDI3 drives tumor cell migration and metastasis

Metastasis from primary tumors remains a major problem for tumor therapy. In the search for markers of metastasis and more effective therapies, the tumor metabolome is relevant because of its importance to the malignant phenotype and metastatic capacity of tumor cells. Altered choline metabolism is a hallmark of cancer. More specifically, a decreased glycerophosphocholine (GPC) to phosphocholine (PC) ratio was reported in breast, ovarian, and prostate cancers. Improved strategies to exploit this altered choline metabolism are therefore required. However, the critical enzyme cleaving GPC to produce choline, the initial step in the pathway controlling the GPC/PC ratio, remained unknown. In the present work, we have identified the enzyme, here named EDI3 (endometrial differential 3). Purified recombinant EDI3 protein cleaves GPC to form glycerol-3-phosphate and choline. Silencing EDI3 in MCF-7 cells decreased this enzymatic activity, increased the intracellular GPC/PC ratio, and decreased downstream lipid metabolites. Downregulating EDI3 activity inhibited cell migration via disruption of the PKCα signaling pathway, with stable overexpression of EDI3 showing the opposite effect. EDI3 was originally identified in our screening study comparing mRNA levels in metastasizing and nonmetastasizing endometrial carcinomas. Both Kaplan-Meier and multivariate analyses revealed a negative association between high EDI3 expression and relapse-free survival time in both endometrial (P < 0.001) and ovarian (P = 0.029) cancers. Overall, we have identified EDI3, a key enzyme controlling GPC and choline metabolism. Because inhibition of EDI3 activity corrects the GPC/PC ratio and decreases the migration capacity of tumor cells, it represents a possible target for therapeutic intervention.     

The presence of α-glucosidase, glycerophosphocholine and carnitine in the epididymis and ejaculate of the vervet monkey (Cercopithecus aethiops) and the Chacma baboon (Papio ursinus)

Summary.  The epididymis is the site of post-testicular sperm maturation in the male genital tract. Studies on human epididymides are hampered by the practical inaccessibility of epididymides of healthy men in their reproductive years. The limited use of laboratory animals therefore seems unavoidable. The objective was to establish baseline values of the epididymal markers α-glucosidase, glycerophosphocholine (GPC) and carnitine in the lumen of the caput, corpus and cauda epididymidis and in the ejaculate of adult male Chacma baboons and vervet monkeys. In both primates, α-glucosidase was found throughout the epididymis and in the ejaculate; values did not vary significantly. In monkeys, the highest concentration of GPC was found in the cauda epididymidis, but smaller amounts were found in the other regions and the ejaculate. In baboons, GPC was absent from the caput, but present in the other regions, including the ejaculate. Carnitine concentrations increased significantly from the caput to the cauda in monkeys and from the caput to the corpus in baboons. With this study, the relative concentration ranges in which these markers are present in the epididymides of these primates have been established. In future studies, changes in concentrations of these substances would probably indicate changes in epididymal function.     

Phenylbutyrate induces apoptosis and lipid accumulations via a peroxisome proliferator‐activated receptor gamma‐dependent pathway

The effects of the selective peroxisome proliferator activated receptor‐gamma (PPAR‐γ) inhibitor GW9662 on phenylbutyrate (PB)‐induced NMR‐detectable lipid metabolites was investigated on DU145 prostate cancer cells. DU145 cells were perfused with 10 mM PB in the presence or absence of 1 µM of GW9662 and the results monitored by ³¹P and diffusion‐weighted ¹H NMR spectroscopy. GW9662 completely reversed PB‐induced NMR‐visible lipid and total choline accumulation in ¹H spectra and glycerophosphocholine and β‐NTP in ³¹P spectra. In addition, pre‐incubation with GW9662 significantly reduced PB‐induced caspase‐3 activation, reversed the G₁ block as measured by flow cytometry, and otherwise had little effect on cell survival as measured by MTT assay. These results suggest that the NMR visible lipid accumulation and apoptosis induced by PB treatment occurs through a mechanism that is mediated by PPAR‐γ. Copyright © 2010 John Wiley & Sons, Ltd.     

Elevated skeletal muscle phosphodiesters in adults using statin medications

Elevated skeletal muscle phosphodiesters (PDE) have previously been reported with muscle-related disorders. Myalgia is a side effect of using statin cholesterol-lowering medications and, therefore, statin use may be associated with increased skeletal muscle PDE. The effect of cholesterol-lowering drugs on skeletal muscle phosphorus metabolites was determined with (31)P magnetic resonance spectroscopy. Resting (31)P metabolites of the anterior compartment muscles were measured in two groups (n = 20; age, 49 +/- 2 years); half were taking statins and the other half were not on these agents. Muscle PDE was 57% greater in the statin group than the control group. These data suggest that statin use increases muscle PDE. Our findings are particularly relevant due to the increasing use and higher dosing of statin medications. Further prospective studies should be performed to document a causal relationship between elevated PDE and statin use, in addition to quantifying correlates to muscle function.     

The influence of inflammation of the human male genital tract on secretion of the seminal markers α-glucosidase, glycerophosphocholine, carnitine, fructose and citric acid

Biochemical analysis was made of specific accessory gland products in the ejaculates of 362 men suffering from various acute inflammatory diseases of the reproductive tract and 33 normozoospermic patients acting as controls. The ejaculate content of the epididymal markers alpha-glucosidase and L-carnitine, but not glycerophosphocholine, was significantly reduced in ejaculates from men with epididymitis; citric acid was reduced in men suffering from prostatitis; both citric acid and alpha-glucosidase were reduced in men suffering from adnexitis. The ejaculate content of epididymal and prostatic markers in prostato-urethritis (adnexitis), where the exact localization of the inflammation was unclear, was not as low as in epididymitis or prostatitis. Seminal vesicle function, as judged from semen volumes and seminal fructose, was not different in these groups of patients. The results, although strongly related to the clinical diagnosis, were unrelated to the microbiological flora of the semen and indicate that both the epididymis and the prostate glands are involved in some forms of adnexitis.     

Absence of correlation between the levels of ATP and other seminal compounds in semen and the results of human in-vitro fertilization

As part of an in-vitro fertilization programme (IVF), semen levels of adenosine triphosphate, fructose, citrate, zinc, free L-carnitine and glycerophosphocholine were measured in 178 men. None of these substances appeared to have any predictive value with regard to the fertilizing potential of the semen during IVF.     

The concentration of some inorganic ions and organic compounds in the luminal fluid of the human ductus deferens

The concentrations of some inorganic ions (sodium, potassium, chloride and phosphate) and organic compounds (carnkine, myo-inositol, glycerophos-phocholine, phosphocholine and total phosphate) were estimated in the luminal fluid collected from sections of human ductus deferens removed at vasectomy. From the data presented it would appear that in contrast to non-primate species, in the human the inorganic ions contribute more to the total osmolarity of the luminal fluid than do the organic compounds.