DHPS-dependent hypusination of eIF5A1/2 is necessary for TGFß/fibronectin-induced breast cancer metastasis and associates with prognostically unfavorable genomic alterations in TP53.

Metastasis is the leading cause of mortality in patients with solid tumors. In this regard, we previously reported that Pseudopodium-Enriched Atypical Kinase One (PEAK1) is necessary for non-canonical Transforming Growth Factor ß (TGFß) signaling and TGFß/fibronectin-induced metastasis. Here, we demonstrate that inhibition of DHPS-dependent eIF5A1/2 hypusination blocks PEAK1 and E-Cadherin expression, breast cancer cell viability and TGFß/fibronectin-induced PEAK1-dependent breast cancer metastasis. Interestingly, TGFß stimulation of high-grade metastatic breast cancer cells increases and sustains eIF5A1/2 hypusination. We used a suite of bioinformatics platforms to search biochemical/functional interactions and clinical databases for additional control points in eIF5A1/2 and PEAK1-Epithelial to Mesenchymal Transition (EPE) pathways. This effort revealed that interacting EPE genes were enriched for TP53 transcriptional targets and were commonly co-amplified in breast cancer patients harboring inactivating TP53 mutations. Taken together, these results suggest that combinatorial therapies targeting DHPS and protein activities elevated in TP53-mutant breast cancers may reduce systemic tumor burden and improve patient outcomes.

p38 and extracellular signal-regulated kinases regulate the myogenic program at multiple steps.

The extracellular signals which regulate the myogenic program are transduced to the nucleus by mitogen-activated protein kinases (MAPKs). We have investigated the role of two MAPKs, p38 and extracellular signal-regulated kinase (ERK), whose activities undergo significant changes during muscle differentiation. p38 is rapidly activated in myocytes induced to differentiate. This activation differs from those triggered by stress and cytokines, because it is not linked to Jun-N-terminal kinase stimulation and is maintained during the whole process of myotube formation. Moreover, p38 activation is independent of a parallel promyogenic pathway stimulated by insulin-like growth factor 1. Inhibition of p38 prevents the differentiation program in myogenic cell lines and human primary myocytes. Conversely, deliberate activation of endogenous p38 stimulates muscle differentiation even in the presence of antimyogenic cues. Much evidence indicates that p38 is an activator of MyoD: (i) p38 kinase activity is required for the expression of MyoD-responsive genes, (ii) enforced induction of p38 stimulates the transcriptional activity of a Gal4-MyoD fusion protein and allows efficient activation of chromatin-integrated reporters by MyoD, and (iii) MyoD-dependent myogenic conversion is reduced in mouse embryonic fibroblasts derived from p38alpha(-/-) embryos. Activation of p38 also enhances the transcriptional activities of myocyte enhancer binding factor 2A (MEF2A) and MEF2C by direct phosphorylation. With MEF2C, selective phosphorylation of one residue (Thr293) is a tissue-specific activating signal in differentiating myocytes. Finally, ERK shows a biphasic activation profile, with peaks of activity in undifferentiated myoblasts and postmitotic myotubes. Importantly, activation of ERK is inhibitory toward myogenic transcription in myoblasts but contributes to the activation of myogenic transcription and regulates postmitotic responses (i.e., hypertrophic growth) in myotubes.

Induction of terminal differentiation by constitutive activation of p38 MAP kinase in human rhabdomyosarcoma cells.

MyoD inhibits cell proliferation and promotes muscle differentiation. A paradoxical feature of rhabdomyosarcoma (RMS), a tumor arising from muscle precursors, is the block of the differentiation program and the deregulated proliferation despite MyoD expression. A deficiency in RMS of a factor required for MyoD activity has been implicated by previous studies. We report here that p38 MAP kinase (MAPK) activation, which is essential for muscle differentiation, is deficient in RMS cells. Enforced induction of p38 MAPK by an activated MAPK kinase 6 (MKK6EE) restored MyoD function and enhanced MEF2 activity in RMS deficient for p38 MAPK activation, leading to growth arrest and terminal differentiation. Stress and cytokines could activate the p38 MAPK in RMS cells, however, these stimuli did not promote differentiation, possibly because they activated p38 MAPK only transiently and they also activated JNK, which could antagonize differentiation. Thus, the selective and sustained p38 MAPK activation, which is distinct from the stress-activated response, is required for differentiation and can be disrupted in human tumors.

Hemodynamic and hormonal changes during pneumoperitoneum and trendelenburg positioning for operative gynecologic laparoscopy surgery.

Objective: The number and types of surgical procedures being preformed using laparoscopic technique is increasing due to technological advances. Recent studies suggest the carbon dioxide pneumoperitoneum and patient positioning causes hemodynamic alterations, respiratory acidosis, and a release of stress hormones. However, to date, no studies have investigated the physiological effect of laparoscopic procedures lasting more than 60 minutes on the stress response and the effect of Trendelenburg positioning. The purpose of this study was to identify the physiological effect of pneumoperitoneum and positioning during prolonged laparoscopy on hemodynamic (cardiac index, mean arterial pressure, heart rate, systemic vascular resistance, and stroke volume), metabolic (arterial blood gases), and hormone (arginine vasopressin, aldosterone, and plasma renin activity) parameters. We hypothesized that pneumoperitoneum and patient positioning will alter the hemodynamic, hormone, and metabolic parameters.Methods: The study was longitudinal in design and sampled a total of 31 healthy subjects having a gynecologic oncologic laparoscopic procedure at Hurley Medical Center, Flint, Michigan. The subjects were randomly assigned one of three groups receiving an initial insufflation pressure of either 10, 15, or 18 mmHg. After obtaining informed consent hemodynamic, metabolic, and hormone measurements were obtained at the following times: 1) pre-induction, 2) post-induction, 3) post-insufflation, 4) post-Trendelenburg 5 minutes and at 30, 60, 90, and 120 minutes post-insufflation. The results were analyzed using multivariate analysis of variance for repeated measures with a P <.05. A power of 0.9 was obtained to identify changes over time.Results: During the time course of the study the hemodynamic, metabolic, and hormonal parameters showed significant alterations. The most dramatic hemodynamic changes occurred post-insufflation characterized by a decrease in cardiac index and stroke volume with a concurrent increase in systemic vascular resistance. The metabolic parameters showed a significant decrease in pH and corresponding increase in PaCO(2). However, the pH and PaCO(2) remained within normal limits through the study. As part of the study's protocol the investigators increased minute volume to control for a rise in PaCO(2) during the procedure. A significant increase was noted in aldosterone and arginine vasopressin at post-insufflation and Trendelenburg positioning. Plasma renin activity showed a dramatic increase following post-insufflation. None of the subjects developed any post anesthetic complications.Conclusion: Our study demonstrated that pneumoperitoneum and Trendelenburg positioning cause statistically significant elevations in the stress hormones and concurrently cause a decrease in hemodynamic parameters. A healthy patient may tolerate these changes but a patient with cardiovascular disease or pulmonary problems may not be able to compensate as efficiently.

The human Aquaporin-5 gene. Molecular characterization and chromosomal localization.

The cDNA for the fifth mammalian aquaporin (AQP5) was isolated from rat, and expression was demonstrated in rat salivary and lacrimal glands, cornea, and lung (Raina, S., Preston, G. M., Guggino, W. B., and Agre, P. (1995) J. Biol. Chem. 270, 1908-1912). Here we report the isolation and characterization of the human AQP5 cDNA and gene. The AQP5 cDNA from a human submaxillary gland library contains a 795-base pair open reading frame encoding a 265-amino acid protein. The deduced amino acid sequences of human and rat AQP5 are 91% identical with 6 substitutions in the 22-amino acid COOH-terminal domain. Expression of human AQP5 in Xenopus oocytes conferred mercurial-sensitive osmotic water permeability (Pf) equivalent to other aquaporins. The human AQP5 structural gene resides within a 7. 4-kilobase SalI-EcoRI fragment with four exons corresponding to amino acids 1-121, 122-176, 177-204, and 205-265 separated by introns of 1.2, 0.5, and 0.9 kilobases. A transcription initiation site was identified 518 base pairs upstream of the initiating methionine. Genomic Southern analysis indicated that AQP5 is a single copy gene which localized to human chromosome 12q13; this coincides with the chromosomal locations of the homologous human genes MIP and AQP2, thus confirming 12q13 as the site of an aquaporin gene cluster. The mouse gene localized to distal chromosome 15. This information may permit molecular characterization of AQP5 expression during normal development and in clinical disorders.

Postoperative nausea and vomiting: a comparison of propofol infusion versus isoflurane inhalational technique for laparoscopic patients.

Gynecologic laparoscopic procedures frequently precipitate postoperative nausea and/or vomiting. The use of specific anesthetic agents and premedicants may decrease the incidence. This study determined the occurrence of postoperative nausea/retching/vomiting (N/R/V) when propofol was used for anesthesia maintenance compared with isoflurane when both groups of patients received metoclopramide and ranitidine preoperatively and were induced with propofol. Sixty American Society of Anesthesiologists (ASA) physical status I or II patients (age 19 to 50 years, weighing 50 to 90 kilograms) who were having elective laparoscopies were evaluated for postoperative N/R/V. No significant difference in the incidence of N/R/V was demonstrated between the propofol and isoflurane groups (P < 0.05). Sixty percent of the patients who received meperidine in the recovery room experienced nausea and/or vomiting. The use of propofol versus isoflurane for maintenance of anesthesia had no effect on the incidence of postoperative N/R/V when patients were premedicated with metoclopramide and ranitidine.

Dependence on chlormethiazole and effects of its withdrawal.

Five cases of physical dependence on chlormethiazole are reported. Because sudden withdrawal may precipitate an acute "organic psychosis", chlormethiazole should only be used in hospitals and, even then, only for a maximum of 9 days.