Inositol Pyrophosphates and Their Unique Metabolic Complexity: Analysis by Gel Electrophoresis

Inositol pyrophosphates are a recently characterized cell signalling molecules responsible for the pyrophosphorylation of protein substrates. Though likely involved in a wide range of cellular functions, the study of inositol pyrophosphates has suffered from a lack of readily available methods for their analysis

Preparation of Quality Inositol Pyrophosphates

Myo-inositol is present in nature either unmodified or in more complex phosphorylated derivates. Of the latest, the two most abundant in eukaryotic cells are inositol pentakisphosphate (IP5) and inositol hexakisphosphate (phytic acid or IP6). IP5 and IP6 are the precursors of inositol pyrophosphate molecules that contain one or more pyrophosphate bonds1. Phosphorylation of IP6 generates diphoshoinositolpentakisphosphate (IP7 or PP-IP5) and bisdiphoshoinositoltetrakisphosphate (IP8 or (PP)2-IP4). Inositol pyrophosphates have been isolated from all eukaryotic organisms so far studied. In addition, the two distinct classes of enzymes responsible for inositol pyrophosphate synthesis are highly conserved throughout evolution2-4

Dissecting the predictive value of MAPK/AKT/estrogen-receptor phosphorylation axis in primary breast cancer to treatment response for tamoxifen over exemestane: a Translational Report of the Intergroup Exemestane Study (IES)-PathIES

Purpose The prognostic and predictive values of the MAPK/AKT/ERα phosphorylation axis (pT202/T204MAPK, pT308AKT, pS473AKT, pS118ERα and pS167ERα) in primary tumours were assessed to determine whether these markers can differentiate between patient responses for switching adjuvant endocrine therapy after 2–3 years from tamoxifen to exemestane and continued tamoxifen monotherapy in the Intergroup Exemestane Study (IES). Methods Of the 4724 patients in IES, 1506 were managed in a subset of centres (N = 89) participating in PathIES. These centres recruited 1282 (85%, 1282/1506) women into PathIES of whom 1036 had phospho-marker data. All phospho-markers were analysed by immunohistochemistry staining. Multivariable Cox proportional hazards models of the phospho-markers for disease-free survival (DFS) and overall survival (OS) were adjusted for clinicopathological factors. Treatment effects on the biomarker expression were determined by interaction tests. Benjamini–Hochberg adjustment for multiple testing with a false discovery rate of 10% was applied (pBH). Results Phospho-T202/T204MAPK, pS118ERα and pS167ERα were all found to be correlated (pBH = 0.0002). These markers were not associated with either DFS or OS when controlling for the established clinicopathological factors. Interaction terms between the phospho-markers and treatment strategies for either DFS or OS were not statistically significant (pBH > 0.05 for all). Conclusions This PathIES study confirmed previously described associations between the phosphorylation site markers of AKT, MAPK and ERα activity in postmenopausal breast cancer patients. No prognostic correlations between the phosphorylation markers and clinical outcome were found, nor were they predictive for clinical outcomes among patients who switched therapy over those treated with tamoxifen alone

Derivation and Validation of a Chronic Total Coronary Occlusion Intervention Procedural Success Score From the 20,000-Patient EuroCTO Registry: The EuroCTO (CASTLE) Score.

OBJECTIVES: The aim was to establish a contemporary scoring system to predict the outcome of chronic total occlusion coronary angioplasty. BACKGROUND: Interventional treatment of chronic total coronary occlusions (CTOs) is a developing subspecialty. Predictors of technical success or failure have been derived from datasets of modest size. A robust scoring tool could facilitate case selection and inform decision making. METHODS: The study analyzed data from the EuroCTO registry. This prospective database was set up in 2008 and includes >20,000 cases submitted by CTO expert operators (>50 cases/year). Derivation (n = 14,882) and validation (n = 5,745) datasets were created to develop a risk score for predicting technical failure. RESULTS: There were 14,882 patients in the derivation dataset (with 2,356 [15.5%] failures) and 5,745 in the validation dataset (with 703 [12.2%] failures). A total of 20.2% of cases were done retrogradely, and dissection re-entry was performed in 9.3% of cases. We identified 6 predictors of technical failure, collectively forming the CASTLE score (Coronary artery bypass graft history, Age (≥70 years), Stump anatomy [blunt or invisible], Tortuosity degree [severe or unseen], Length of occlusion [≥20 mm], and Extent of calcification [severe]). When each parameter was assigned a value of 1, technical failure was seen to increase from 8% with a CASTLE score of 0 to 1, to 35% with a score ≥4. The area under the curve (AUC) was similar in both the derivation (AUC: 0.66) and validation (AUC: 0.68) datasets. CONCLUSIONS: The EuroCTO (CASTLE) score is derived from the largest database of CTO cases to date and offers a useful tool for predicting procedural outcome

Ki67 Is an Independent Predictor of Recurrence in the Largest Randomized Trial of 3 Radiation Fractionation Schedules in Localized Prostate Cancer

Purpose: To assess whether the cellular proliferation marker Ki67 provides prognostic information and predicts response to radiation therapy fractionation in patients with localized prostate tumors participating in a randomized trial of 3 radiation therapy fractionation schedules (74 Gy/37 fractions vs 60 Gy/20 fractions vs 57 Gy/19 fractions). Methods and Materials: A matched case–control study design was used; patients with biochemical/clinical failure >2 years after radiation therapy (BCR) were matched 1:1 to patients without recurrence using established prognostic factors (Gleason score, prostate-specific antigen, tumor stage) and fractionation schedule. Immunohistochemistry was used to stain diagnostic biopsy specimens for Ki67, which were scored using the unweighted global method. Conditional logistic regression models estimated the prognostic value of mean and maximum Ki67 scores on BCR risk. Biomarker–fractionation interaction terms determined whether Ki67 was predictive of BCR by fractionation. Results: Using 173 matched pairs, the median for mean and maximum Ki67 scores were 6.6% (interquartile range, 3.9%-9.8%) and 11.0% (interquartile range, 7.0%-15.0%) respectively. Both scores were significant predictors of BCR in models adjusted for established prognostic factors. Conditioning on matching variables and age, the odds of BCR were estimated to increase by 9% per 1% increase in mean Ki67 score (odds ratio 1.09; 95% confidence interval 1.04-1.15, P =.001). Interaction terms between Ki67 and fractionation schedules were not statistically significant. Conclusions: Diagnostic Ki67 did not predict BCR according to fractionation schedule in CHHiP; however, it was a strong independent prognostic factor for BCR

Identification of an Evolutionarily Conserved Family of Inorganic Polyphosphate Endopolyphosphatases

Inorganic polyphosphate (poly-P) consists of just a chain of phosphate groups linked by high energy bonds. It is found in every organism and is implicated in a wide variety of cellular processes (e.g. phosphate storage, blood coagulation, and pathogenicity). Its metabolism has been studied mainly in bacteria while remaining largely uncharacterized in eukaryotes. It has recently been suggested that poly-P metabolism is connected to that of highly phosphorylated inositol species (inositol pyrophosphates). Inositol pyrophosphates are molecules in which phosphate groups outnumber carbon atoms. Like poly-P they contain high energy bonds and play important roles in cell signaling. Here, we show that budding yeast mutants unable to produce inositol pyrophosphates have undetectable levels of poly-P. Our results suggest a prominent metabolic parallel between these two highly phosphorylated molecules. More importantly, we demonstrate that DDP1, encoding diadenosine and diphosphoinositol phosphohydrolase, possesses a robust poly-P endopolyphosphohydrolase activity. In addition, we prove that this is an evolutionarily conserved feature because mammalian Nudix hydrolase family members, the three Ddp1 homologues in human cells (DIPP1, DIPP2, and DIPP3), are also capable of degrading poly-P