Peter S. Dahlberg

Nontoxic chemical interdiction of the epithelial-to-mesenchymal transition by targeting cap-dependent translation

Normal growth and development depends upon high fidelity regulation of cap-dependent translation initiation, a process that is usurped and redirected in cancer to mediate acquisition of malignant properties. The epithelial-to-mesenchymal transition (EMT) is a key translationally regulated step in the development of epithelial cancers and pathological tissue fibrosis. To date, no compounds targeting EMT have been developed. Here we report the synthesis of a novel class of histidine triad nucleotide binding protein (HINT)-dependent pronucleotides that interdict EMT by negatively regulating the association of eIF4E with the mRNA cap. Compound eIF4E inhibitor-1 potently inhibited cap-dependent translation in a dose-dependent manner in zebrafish embryos without causing developmental abnormalities and prevented eIF4E from triggering EMT in zebrafish ectoderm explants without toxicity. Metabolism studies with whole cell lysates demonstrated that the prodrug was rapidly converted into 7-BnGMP. Thus we have successfully developed the first nontoxic small molecule able to inhibit EMT, a key process in the development of epithelial cancer and tissue fibrosis, by targeting the interaction of eIF4E with the mRNA cap and demonstrated the tractability of zebrafish as a model organism for studying agents that modulate EMT. Our work provides strong motivation for the continued development of compounds designed to normalize cap-dependent translation as novel chemo-preventive agents and therapeutics for cancer and fibrosis.

Ninety-day mortality and major complications are not affected by use of lung allocation score.

BACKGROUND In May 2005 the Organ Procurement Transplant Network (OPTN) and United Network for Organ Sharing (UNOS) implemented the donor lung allocation score (LAS) system to prioritize organ allocation among prospective transplant recipients. The purpose of our study was to determine the impact of LAS implementation on 90-day survival, early complications and incidence of severe primary graft dysfunction (PGD) after the transplant procedure. METHODS Early outcomes among 78 patients receiving transplants after the initiation of the scoring system were compared with those of the 78 previous patients. Survival rates at 90 days and 1 year were the primary end-points of the study. Arterial blood-gas measurements were collected for all patients at the time of ICU arrival and at 12, 24 and 48 hours after surgery to determine the distribution of International Society of Heart and Lung Transplant (ISHLT) PGD grade. Major complications within 30 days post-transplant were recorded. RESULTS We found a small but significant 1-year survival advantage among post-LAS implementation patients, which was largely due to decreased early mortality in comparison to the control cohort. The incidence of ISHLT Grade 3 PGD measured within the first 24 hours after transplant did not differ between groups, nor was there an increase in the rate of major post-operative complications. CONCLUSIONS Implementation of the LAS system has not been associated with an increase in early mortality, immediate PGD or major complications.

Volume-Outcome Relationship for Coronary Artery Bypass Grafting in an Era of Decreasing Volume

HYPOTHESIS We hypothesized that the recent reduction in procedure volume for coronary artery bypass grafting (CABG) has led to an increase in the in-hospital mortality rate. DESIGN Hospital discharge data from the Nationwide Inpatient Sample from January 1, 1988, through December 31, 2003. SETTING A 20% random sample of patients admitted to US hospitals. PATIENTS All patients who underwent CABG or percutaneous transluminal coronary interventions. Facilities performing CABG were assigned to standard volume cutoffs. MAIN OUTCOME MEASURES Rates of cardiac procedures and the proportion of hospitals meeting standard volume cutoffs, as well as the CABG mortality rate. RESULTS During our 16-year study period, the rate of CABG increased from 7.2 cases per 1000 discharges in 1988 to 12.2 cases in 1997 but then decreased to 9.1 cases in 2003, while the rate of percutaneous interventions tripled. For CABG, the proportion of high-volume hospitals declined from 32.5% in 1997 to 15.5% in 2003. Despite shifts between high- and low-volume hospitals, the CABG mortality rate steadily declined from 5.4% in 1988 to 3.3% in 2003. Hospitals performing the lowest volume of CABG experienced the largest decrease in the in-hospital mortality rate. CONCLUSIONS Since 1997, CABG volume has declined in the setting of a decrease in in-hospital mortality. A lower mortality rate in the setting of reduced CABG volume is a counterintuitive finding, suggesting that procedure volume is an insufficient predictor of outcome on which to base regionalization strategies.

Evolution of clipping for thoracoscopic sympathectomy in symptomatic hyperhidrosis.

Background Severe hyperhidrosis is treated by thoracic sympathetic chain interrupting through chain transection or clipping. Our study compared the efficacy of these 2 methods. Methods Retrospectively, patients who underwent thoracoscopic sympathectomy from 1999 to 2005 had demographic, operative, and postoperative data analyzed. Results Fifty-four operations were performed for refractory sweating of the palm (72%), axilla (66%), foot (53%), and head/neck (19%). Thirty-seven (69%) underwent clipping; 17 (31%) underwent chain transection. There was no difference in age, sex, or blood loss. One ganglion level was interrupted in 24.1% and 2 levels in 75.4%. Bothersome compensatory hyperhidrosis occurred in 13% (5—clipping and 2—transection). One patient underwent clip removal for debilitating symptoms. Three small pneumothoraces occurred (all in the transection group); all treated expectantly. Conclusions Thoracoscopic sympathectomy is a safe outpatient procedure. Both methods yield excellent results with minimal compensatory hyperhidrosis. Thoracoscopic sympathetic chain clipping and transection are equivalent.

Design of a potent novel endotoxin antagonist

BACKGROUND Bactericidal permeability increasing protein (BPI) binds to and neutralizes lipopolysaccharide (LPS, endotoxin). Small synthetic peptides based on the amino acid sequence of the LPS binding domain of BPI neutralize LPS, albeit inefficiently. Although the LPS binding domain of native BPI possesses a beta-turn secondary structure, this structure is not present in small derivative peptides. The purpose of this study was to determine whether the addition of a beta-turn to a BPI-derived peptide is associated with more potent endotoxin antagonism. METHODS We generated a hybrid peptide (BU3) on the basis of (1) a portion of the LPS binding domain from BPI and (2) amino acids known to initiate a beta-turn. BU3 folds with a beta-turn, and we tested its effects on LPS neutralization and LPS-induced tumor necrosis factor-alpha secretion, comparing it with BPI-derived peptide BG22 that lacks a beta-turn and to an irrelevant peptide (BG16). RESULTS Compared with BG22, BU3 demonstrated enhanced LPS neutralization and inhibition of LPS-induced tumor necrosis factor-alpha secretion in vitro and a similar diminution of endotoxemia and tumor necrosis factor-alpha secretion in a murine model of endotoxemia. CONCLUSIONS These data demonstrate the potential for enhancing the biologic activity of a BPI-derived peptide endotoxin antagonist via manipulation of its conformational structure.

Cap-dependent mRNA translation and the ubiquitin-proteasome system cooperate to promote ERBB2-dependent esophageal cancer phenotype

Pathological post-transcriptional control of the proteome composition is a central feature of malignancy. Two steps in this pathway, eIF4F-driven cap-dependent mRNA translation and the ubiquitin-proteasome system (UPS), are deregulated in most if not all cancers. We tested a hypothesis that eIF4F is aberrantly activated in human esophageal adenocarcinoma (EAC) and requires elevated rates of protein turnover and proteolysis and thereby activated UPS for its pro-neoplastic function. Here, we show that 80% of tumors and cell lines featuring amplified ERBB2 display an aberrantly activated eIF4F. Direct genetic targeting of the eIF4F in ERBB2-amplified EAC cells with a constitutively active form of the eIF4F repressor 4E-BP1 decreased colony formation and proliferation and triggered apoptosis. In contrast, suppression of m-TOR-kinase activity towards 4E-BP1with rapamycin only modestly inhibited eIF4F-driven cap-dependent translation and EAC malignant phenotype; and promoted feedback activation of other cancer pathways. Our data show that co-treatment with 2 FDA-approved agents, the m-TOR inhibitor rapamycin and the proteasome inhibitor bortezomib, leads to strong synergistic growth-inhibitory effects. Moreover, direct targeting of eIF4F with constitutively active 4E-BP1 is significantly more potent in collaboration with bortezomib than rapamycin. These data support the hypothesis that a finely tuned balance between eIF4F-driven protein synthesis and proteasome-mediated protein degradation is required for the maintenance of ERBB2-mediated EAC malignant phenotype. Altogether, our study supports the development of pharmaceuticals to directly target eIF4F as most efficient strategy; and provides a clear rationale for the clinical evaluation of combination therapy with m-TOR inhibitors and bortezomib for EAC treatment.

ERBB2 suppression decreases cell growth via apoptosis in gastrointestinal adenocarcinomas

BACKGROUND Although the incidence of adenocarcinoma of the esophageal and gastroesophageal junction has increased at an alarming rate in the past 30 years, little improvement has been made in treatment strategies. Previous studies have demonstrated that many upper gastrointestinal (GI) adenocarcinomas exhibit ERBB2 amplification. In cancers proven to have similar amplification, such as breast, ERBB2-targeted therapies have dramatically improved overall survival and disease-free rates of survival. This study uses siRNA to knockdown ERBB2 in GI adenocarcinoma cell lines to evaluate cell viability, apoptosis, and changes in cell cycle. METHODS A cell line with a baseline amount of ERBB2 (Seg-1) and 2 upper GI adenocarcinoma cell lines with known amplification of ERBB2 (esophageal [OE19] and gastric [MKN45]) were treated with 120 pmol of 1 of 2 independent ERBB2 siRNAs or control siRNA for 6 hours. RESULTS We demonstrate that knockdown of ERBB2 in esophageal and gastric cancer cell lines with known ERBB2 amplification effectively decreases ERBB2 protein levels and decreases cell viability mainly via apoptotic pathways. CONCLUSION ERBB-directed therapy may be of benefit in the subset of patients with GI adenocarcinomas exhibiting amplification of ERBB2.

A randomized, placebo-controlled trial of aprotinin to reduce primary graft dysfunction following lung transplantation

Herrington CS, Prekker ME, Arrington AK, Susanto D, Baltzell JW, Studenski LL, Radosevich DM, Kelly RF, Shumway SJ, Hertz MI, Bittner HB, Dahlberg PS. A randomized, placebo‐controlled trial of aprotinin to reduce primary graft dysfunction following lung transplantation.
Clin Transplant 2011: 25: 90–96.

Aprotinin Decreases Lung Reperfusion Injury and Dysfunction

Reduced lung perfusion and subsequent pulmonary ischemia can cause increased pulmonary vascular resistance, decreased oxygenation capacity, worsened compliance, and edema formation.