Joseph E. Ippolito

Molecular properties of adult mouse gastric and intestinal epithelial progenitors in their niches

We have sequenced 36,641 expressed sequence tags from laser capture microdissected adult mouse gastric and small intestinal epithelial progenitors, obtaining 4031 and 3324 unique transcripts, respectively. Using Gene Ontology (GO) terms, each data set was compared with cDNA libraries from intact adult stomach and small intestine. Genes in GO categories enriched in progenitors were filtered against genes in GO categories represented in hematopoietic, neural, and embryonic stem cell transcriptomes and mapped onto transcription factor networks, plus canonical signal transduction and metabolic pathways. Wnt/β-catenin, phosphoinositide-3/Akt kinase, insulin-like growth factor-1, vascular endothelial growth factor, integrin, and γ-aminobutyric acid receptor signaling cascades, plus glycerolipid, fatty acid, and amino acid metabolic pathways are among those prominently represented in adult gut progenitors. The results reveal shared as well as distinctive features of adult gut stem cells when compared with other stem cell populations.

Linkage between cellular communications, energy utilization, and proliferation in metastatic neuroendocrine cancers

To identify metabolic features that support the aggressive behavior of human neuroendocrine (NE) cancers, we examined metastatic prostate NE tumors and derived prostate NE cancer (PNEC) cell lines from a transgenic mouse model using a combination of magic angle spinning NMR spectroscopy, in silico predictions of biotransformations that observed metabolites may undergo, biochemical tests of these predictions, and electrophysiological/calcium imaging studies. Malignant NE cells undergo excitation and increased proliferation when their GABAA, glutamate, and/or glycine receptors are stimulated, use glutamate and GABA as substrates for NADH biosynthesis, and produce propylene glycol, a precursor of pyruvate derived from glycine that increases levels of circulating free fatty acids through extra-NE cell effects. Treatment of nude mice containing PNEC tumor xenografts with (i) amiloride, a diuretic that inhibits Abp1, an enzyme involved in NE cell GABA metabolism, (ii) carbidopa, an inhibitor of dopa decarboxylase which functions upstream of Abp1, plus (iii) flumazenil, a benzodiazepine antagonist that binds to GABAA receptors, leads to significant reductions in tumor growth. These findings may be generally applicable: GeneChip data sets from 471 human neoplasms revealed that components of GABA metabolic pathways, including ABP1, exhibit statistically significant increases in their expression in NE and non-NE cancers.

A Fluorescence-Coupled Assay for Gamma Aminobutyric Acid (GABA) Reveals Metabolic Stress-Induced Modulation of GABA Content in Neuroendocrine Cancer

Pathways involved in the synthesis of the neurotransmitter gamma-aminobutyric acid (GABA) have been implicated in the pathogenesis of high grade neuroendocrine (NE) neoplasms as well as neoplasms from a non-NE lineage. Using The Cancer Genome Atlas, overexpression of the GABA synthetic enzyme, glutamate decarboxylase 1 (GAD1), was found to be associated with decreased disease free-survival in prostate adenocarcinoma and decreased overall survival in clear cell renal cell carcinomas. Furthermore, GAD1 was found to be expressed in castrate-resistant prostate cancer cell lines, but not androgen-responsive cell lines. Using a novel fluorescence-coupled enzymatic microplate assay for GABA mediated through reduction of resazurin in a prostate neuroendocrine carcinoma (PNEC) cell line, acid microenvironment-induced stress increased GABA levels while alkaline microenvironment-induced stress decreased GABA through modulation of GAD1 and glutamine synthetase (GLUL) activities. Moreover, glutamine but not glucose deprivation decreased GABA through modulation of GLUL. Consistent with evidence in prokaryotic and eukaryotic organisms that GABA synthesis mediated through GAD1 may play a crucial role in surviving stress, GABA may be an important mediator of stress survival in neoplasms. These findings identify GABA synthesis and metabolism as a potentially important pathway for regulating cancer cell stress response as well as a potential target for therapeutic strategies.

Acidic extracellular pH of tumors induces octamer-binding transcription factor 4 expression in murine fibroblasts in vitro and in vivo.

Octamer-binding transcription factor 4 (OCT-4) is an important marker of cellular de-differentiation that can be induced by environmental stressors, such as acidity. Here we demonstrate that chronic acidic stress in solid tumors induced OCT-4 expression in fibroblasts and other stromal cells in four tumor models. The results have implications for how tumors utilize pH modulation to recruit associated stromal cells, induce partial reprogramming of tumor-associated stromal cells, and respond to therapy.

Extracellular pH Modulates Neuroendocrine Prostate Cancer Cell Metabolism and Susceptibility to the Mitochondrial Inhibitor Niclosamide

Neuroendocrine prostate cancer is a lethal variant of prostate cancer that is associated with castrate-resistant growth, metastasis, and mortality. The tumor environment of neuroendocrine prostate cancer is heterogeneous and characterized by hypoxia, necrosis, and numerous mitoses. Although acidic extracellular pH has been implicated in aggressive cancer features including metastasis and therapeutic resistance, its role in neuroendocrine prostate cancer physiology and metabolism has not yet been explored. We used the well-characterized PNEC cell line as a model to establish the effects of extracellular pH (pH 6.5, 7.4, and 8.5) on neuroendocrine prostate cancer cell metabolism. We discovered that alkalinization of extracellular pH converted cellular metabolism to a nutrient consumption-dependent state that was susceptible to glucose deprivation, glutamine deprivation, and 2-deoxyglucose (2-DG) mediated inhibition of glycolysis. Conversely, acidic pH shifted cellular metabolism toward an oxidative phosphorylation (OXPHOS)-dependent state that was susceptible to OXPHOS inhibition. Based upon this mechanistic knowledge of pH-dependent metabolism, we identified that the FDA-approved anti-helminthic niclosamide depolarized mitochondrial potential and depleted ATP levels in PNEC cells whose effects were enhanced in acidic pH. To further establish relevance of these findings, we tested the effects of extracellular pH on susceptibility to nutrient deprivation and OXPHOS inhibition in a cohort of castrate-resistant prostate cancer cell lines C4-2B, PC-3, and PC-3M. We discovered similar pH-dependent toxicity profiles among all cell lines with these treatments. These findings underscore a potential importance to acidic extracellular pH in the modulation of cell metabolism in tumors and development of an emerging paradigm that exploits the synergy of environment and therapeutic efficacy in cancer.

Prostate Magnetic Resonance Imaging: Challenges of Implementation

Prostate cancer is among the most common causes of cancer and cancer deaths in men. Screening methods and optimal treatments have become controversial in recent years. Prostate magnetic resonance imaging (MRI) is gaining popularity as a tool to assist diagnosis, risk assessment, and staging. However, implementation into clinical practice can be difficult, with many challenges associated with image acquisition, postprocessing, interpretation, reporting, and radiologic-pathologic correlation. Although state-of-the-art technology is available at select sites for targeting tissue biopsy and interpreting multiparametric prostate MRI, many institutions struggle with adapting this new technology into an efficient multidisciplinary model of patient care. This article reviews several of the challenges that radiologists should be aware of when integrating prostate MRI into their clinical practice.

Current concepts in neuroendocrine cancer metabolism.

Neuroendocrine (NE) cancers occur in multiple anatomic locations and range in prognosis from indolent to aggressive. In addition, adenocarcinomas can express gene products associated with NE cells, referred to as NE differentiation (NED), which correlates with poor prognosis and aggressive disease. Several metabolites and peptides produced by NE cells have been discovered that engage in cellular signaling and have autocrine and paracrine effects on cancer cell proliferation. This review focuses on the current knowledge of small molecule metabolism in NE cancers involving the synthesis of biogenic amine, polyamine, and amino acid neurotransmitters. Systems biology-directed approaches to NE cancer metabolism using gene expression profiling, liquid chromatography/mass spectrometry (LC/MS) and nuclear magnetic resonance (NMR) are also discussed. Furthermore, knowledge of metabolic and signaling pathways in NE cancers has led to the successful implementation of therapeutic regimens in cell culture and animal models of NE carcinogenesis.

Beyond Seed and Soil: Understanding and Targeting Metastatic Prostate Cancer; Report From the 2016 Coffey–Holden Prostate Cancer Academy Meeting

The 2016 Coffey–Holden Prostate Cancer Academy (CHPCA) Meeting, “Beyond Seed and Soil: Understanding and Targeting Metastatic Prostate Cancer,” was held from June 23 to June 26, 2016, in Coronado, California.

Radiogenomics of High-Grade Serous Ovarian Cancer: Multireader Multi-Institutional Study from the Cancer Genome Atlas Ovarian Cancer Imaging Research Group

Purpose To evaluate interradiologist agreement on assessments of computed tomography (CT) imaging features of high-grade serous ovarian cancer (HGSOC), to assess their associations with time-to-disease progression (TTP) and HGSOC transcriptomic profiles (Classification of Ovarian Cancer [CLOVAR]), and to develop an imaging-based risk score system to predict TTP and CLOVAR profiles. Materials and Methods This study was a multireader, multi-institutional, institutional review board-approved, HIPAA-compliant retrospective analysis of 92 patients with HGSOC (median age, 61 years) with abdominopelvic CT before primary cytoreductive surgery available through the Cancer Imaging Archive. Eight radiologists from the Cancer Genome Atlas Ovarian Cancer Imaging Research Group developed and independently recorded the following CT features: characteristics of primary ovarian mass(es), presence of definable mesenteric implants and infiltration, presence of other implants, presence and distribution of peritoneal spread, presence and size of pleural effusions and ascites, lymphadenopathy, and distant metastases. Interobserver agreement for CT features was assessed, as were univariate and multivariate associations with TTP and CLOVAR mesenchymal profile (worst prognosis). Results Interobserver agreement for some features was strong (eg, α = .78 for pleural effusion and ascites) but was lower for others (eg, α = .08 for intraparenchymal splenic metastases). Presence of peritoneal disease in the right upper quadrant (P = .0003), supradiaphragmatic lymphadenopathy (P = .0004), more peritoneal disease sites (P = .0006), and nonvisualization of a discrete ovarian mass (P = .0037) were associated with shorter TTP. More peritoneal disease sites (P = .0025) and presence of pouch of Douglas implants (P = .0045) were associated with CLOVAR mesenchymal profile. Combinations of imaging features contained predictive signal for TTP (concordance index = 0.658; P = .0006) and CLOVAR profile (mean squared deviation = 1.776; P = .0043). Conclusion These results provide some evidence of the clinical and biologic validity of these image features. Interobserver agreement is strong for some features, but could be improved for others.

Sexual dimorphism in glioma glycolysis underlies sex differences in survival

The molecular bases for sex differences in cancer remain undefined and how to incorporate them into risk stratification remains undetermined. Given sex differences in metabolism and the inverse correlation between fluorodeoxyglucose (FDG) uptake and survival, we hypothesized that glycolytic phenotyping would improve glioma subtyping. Using retrospectively acquired lower-grade glioma (LGG) transcriptome data from The Cancer Genome Atlas (TCGA), we discovered male-specific decreased survival resulting from glycolytic gene overexpression. Patients within this high-glycolytic group showed significant differences in the presence of key genomic alterations (i.e., 1p/19q codeletion, CIC, EGFR, NF1, PTEN, FUBP1, and IDH mutations) compared with the low-glycolytic group. Although glycolytic stratification defined poor prognostic males independent of grade, histology, TP53, and ATRX mutation status, we unexpectedly found that females with high-glycolytic gene expression and wild-type IDH survived longer than all other wild-type patients. Validation with an independent metabolomics dataset from grade 2 gliomas determined that glycolytic metabolites selectively stratified males and also uncovered a potential sexual dimorphism in pyruvate metabolism. These findings identify a potential synergy between patient sex, tumor metabolism, and genomic alterations in determining outcome for glioma patients.