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Biomedical subjects

Steven C Cunningham

Publications and source records attributed to Steven C Cunningham.

At least 19 recordsLinked to original sources
PubMed2006

Targeted deletion of MKK4 in cancer cells: a detrimental phenotype manifests as decreased experimental metastasis and suggests a counterweight to the evolution of tumor-suppressor loss.

Tumor-suppressors have commanded attention due to the selection for their inactivating mutations in human tumors. However, relatively little is understood about the inverse, namely, that tumors do not select for a large proportion of seemingly favorable mutations in tumor-suppressor genes. This could be explained by a detrimental phenotype accruing in a cell type-specific manner to most cells experiencing a biallelic loss. For example, MKK4, a tumor suppressor gene distinguished by a remarkably consistent mutational rate across diverse tumor types and an unusually high rate of loss of heterozygosity, has the surprisingly low rate of genetic inactivation of only approximately 5%. To explore this incongruity, we engineered a somatic gene knockout of MKK4 in human cancer cells. Although the null cells resembled the wild-type cells regarding in vitro viability and proliferation in plastic dishes, there was a marked difference in a more relevant in vivo model of experimental metastasis and tumorigenesis. MKK4(-/-) clones injected i.v. produced fewer lung metastases than syngeneic MKK4-competent cells (P = 0.0034). These findings show how cell type-specific detrimental phenotypes can offer a paradoxical and yet key counterweight to the selective advantage attained by cells as they experiment with genetic null states during tumorigenesis, the resultant balance then determining the observed biallelic mutation rate for a given tumor-suppressor gene.

Animals↗
PubMed2006

Theoretical proposal: allele dosage of MAP2K4/MKK4 could rationalize frequent 17p loss in diverse human cancers.

Although aneuploidy is a global genomic abnormality present in most human cancers, the clonal selection model best explains the action of select activating mutations in oncogenes and homozygous losses of tumor-suppressor genes. Simple gene dosage changes are difficult however, to incorporate into this model, in part due to negative feedback loops that govern major cancer mutational targets (e.g., TP53, PTCH, SMAD4) and essentially preclude a haploinsufficient phenotype. The 17p conundrum may offer a clue to reconciling this difficulty: In comparison to the moderate mutation rate of TP53, many tumors have a disproportionately high frequency of loss of 17p. This discrepancy, and similar discrepancies at other sites of LOH, has long been thought to be due to the presence of undiscovered yet frequently mutated tumor-suppressor genes. However, over 15 years of searching for this grail has distributed bountiful disappointment. It is perhaps time to seriously consider an alternative explanation. Located on 17p adjacent to the TP53 gene, MKK4 is one of the most consistently mutated genes across tumor types, and is located on one of the most frequently lost arms in the human genome. We theorized that a gene dosage-dependent phenotype of MKK4 could plausibly promote the emergence of 17p LOH and thereby the probability of evolving the biallelic inactivation of TP53. Using MKK4 somatic human knockout cancer cells, we observed the proof-of-principle in the downstream gene dosage-dependent phenotypes: heterozygous and homozygous knockouts were progressively deficient in Mkk4 protein, in stress-induced phosphorylation of Jnk, and the resultant upregulation of JUN mRNA. These observations highlight a lack of compensatory regulation when gene dosage changes perturb the Jnk-Jun relationship. Consideration of gene dosage changes specifically affecting members of positive feedback loops may permit integration of the aneuploidy process into a conventional model of clonal selection in tumorigenesis.

Cell Line, Tumor↗
PubMed2006

MKK4 status predicts survival after resection of gastric adenocarcinoma.

HYPOTHESIS: Lack of expression of the tumor-suppressor gene MKK4 is significantly correlated with poor survival after resection of gastric adenocarcinoma. DESIGN: Retrospective review of medical records after construction and immunolabeling of tissue microarrays for clinical correlation. SETTING: The Johns Hopkins Hospital, Baltimore, Md. PATIENTS: Patients operated on because of gastric adenocarcinoma between 1983 and 1995. Main Outcome Measure Long-term survival and MKK4 status. RESULTS: Primary tumors (N = 124) were scored as 0 (no labeling), 1+ (weak labeling), or 2+ (strong labeling) in 9 (7%), 80 (65%), and 35 (28%) patients, and 5-year survival in these patients was 0%, 21%, and 28%, respectively. Given the small size (7%) of the MKK4-negative group (as expected, given the 5%-10% incidence of genetic loss in carcinomas), a Cox proportional hazards analysis was performed, adjusting for age, sex, and tumor stage. This multivariate analysis revealed a 5-fold increased risk of death (P<.001) in patients whose primary tumors were MKK4-negative. Furthermore, the addition of MKK4 status significantly improved the Cox model, changing log likelihood from -1410 to -369, confirming that MKK4 status was truly the effector of the survival difference and not a bystander. CONCLUSIONS: The lack of expression of the tumor-suppressor gene MKK4 in resected gastric adenocarcinoma is robustly associated with poor survival. This finding may provide a useful prognostic tool in patients with gastric adenocarcinoma.

Adenocarcinoma↗
PubMed2006

Pancreaticoduodenectomy in the very elderly.

It is estimated that by 2050, there will be a 300% increase in the elderly population (> or =65 years) and a corresponding increase in elderly patients presenting for surgical evaluation. Surgical decision-making in this population can be difficult because outcomes in the elderly are poorly defined. We reviewed 2698 consecutive pancreaticoduodenectomies (PDs) at our institution over a 35-year period (April 1970 through March 2005), with the last 1000 resections being done in the last 4 years. Data collected included surgical indication, mortality (defined as 30-day or in-hospital mortality), complications, and survival. Patients were divided by age into three groups (<80, 80-89, and > or =90 years) and evaluated using multiple logistic regression. Two hundred seven patients > or =80 years old underwent a PD (7.7% of 2698). Patients 80-89 years of age had a mortality rate of 4.1% (8 of 197) and a complication rate of 52.8% (99 of 197), whereas patients < or =79 years of age had a mortality of 1.7% and a complication rate of 41.6% (P < 0.05). There were no perioperative deaths among the 10 patients > or =90 years of age, and their complication rate was 50% (5 of 10). One-year survival for patients 80-89 years of age was 59.1%, and that for patients > or =90 years was 60%. Age was not an independent risk factor for perioperative mortality and morbidity following PD after adjusting for preoperative comorbidities. We demonstrate that PD can be safely performed in patients over 80 years of age and conclude that age alone should not be a contraindication to pancreatic resection. The advent of improved surgical outcomes and an aging population will likely result in a significant increase in the number of PDs performed in the next few decades.

Age Factors↗
PubMed2006

Targeted disruption of FANCC and FANCG in human cancer provides a preclinical model for specific therapeutic options.

BACKGROUND & AIMS: How specifically to treat pancreatic and other cancers harboring Fanconi anemia gene mutations has raised great interest recently, yet preclinical studies have been hampered by the lack of well-controlled human cancer models. METHODS: We endogenously disrupted FANCC and FANCG in a human adenocarcinoma cell line and determined the impact of these genes on drug sensitivity, irradiation sensitivity, and genome maintenance. RESULTS: FANCC and FANCG disruption abrogated FANCD2 monoubiquitination, confirming an impaired Fanconi anemia pathway function. On treatment with DNA interstrand-cross-linking agents, FANCC and FANCG disruption caused increased clastogenic damage, G2/M arrest, and decreased proliferation. The extent of hypersensitivity varied among agents, with ratios of inhibitory concentration 50% ranging from 2-fold for oxaliplatin to 14-fold for melphalan, a drug infrequently used in solid tumors. No hypersensitivity was observed on gemcitabine, etoposide, 3-aminobenzamide, NU1025, or hydrogen peroxide. FANCC and FANCG disruption also resulted in increased clastogenic damage on irradiation, but only FANCG disruption caused a subsequent decrease in relative survival. Finally, FANCC and FANCG disruption increased spontaneous chromosomal breakage, supporting the role of these genes in genome maintenance and likely explaining why they are mutated in sporadic cancer. CONCLUSIONS: Our human cancer cell model provides optimal controls to elucidate fundamental biologic features of individual Fanconi anemia gene defects and facilitates preclinical studies of therapeutic options. The impact of Fanconi gene defects on drug and irradiation sensitivity renders these genes promising targets for a specific, genotype-based therapy for individual cancer patients, providing a strong rationale for clinical trials.

Adenocarcinoma↗
PubMed2006

Serum lipopolysaccharide-binding protein concentrations in trauma victims.

BACKGROUND: In low concentrations, lipopolysaccharide-binding protein (LBP), an acute-phase protein recognizing lipopolysaccharide (LPS), catalyzes its transfer to the cellular receptor consisting of CD14 and Toll-like receptor-4. Previous studies have documented increased serum LBP concentrations in patients with sepsis, systemic inflammatory response syndrome (SIRS), or acute pancreatitis and after cardiopulmonary bypass. No prior studies have examined LBP expression in trauma victims. We hypothesized that admission LBP plasma concentrations are predictive of outcome (mortality) in trauma. This study assessed time-dependent changes in serum LBP concentrations in trauma patients soon after injury. METHODS: A prospective, single-institution, observational cohort study of 121 adult trauma patients (age > or =17 years) with moderate to severe injury who required hospitalization. The trauma patients were male in 79.6% of the cases and had a mean age of 43.0 +/- 20.6 years. The mean injury severity score (ISS) was 23 +/- 12, and the crystalloid resuscitation volume given in the first 24 h averaged 6,640 +/- 3,729 mL. Informed consent was obtained on admission, and blood samples were drawn on admission and at 24 h postadmission. Prospective data were collected for daily SIRS score, multiple organ dysfunction score (MODS), and sequential organ failure assessment (SOFA) score, complications, and outcomes. Plasma concentrations of LBP were measured by enzyme-linked immunosorbent assay. RESULTS: Sixty patients (48.8% of the study cohort) required emergency surgical intervention and sustained a substantial intraoperative blood loss (mean 1,404 +/- 2,757 mL). The hospital mortality rate was 16.3% (20 patients). The mean intensive care unit stay was 8.9 +/- 16.4 days, and the hospital stay was 14.8 +/- 19.6 days. The patients had a significantly higher serum concentrations of LBP on admission (mean 28.0 +/- 25.3 mg/L; range 2-100 mg/L) than did control subjects (mean 6.2 +/- 2.1 mg/L; range 1.3-12.8 mg/L; p < 0.01), similar to the plasma concentrations previously reported in septic patients. A significant increase in LBP concentration was noted at 24 h (mean 72.3 +/- 45.7 mg/L; range 8-210 mg/L; p < 0.05). The admission LBP concentration was significantly greater in nonsurvivors than in survivors. However, after controlling for age and ISS, the admission LBP concentration did not predict death.

Acute-Phase Proteins↗
PubMed2006

Assessment of complications after pancreatic surgery: A novel grading system applied to 633 patients undergoing pancreaticoduodenectomy.

OBJECTIVE: To define a simple and reproducible classification of complications following pancreaticoduodenectomy (PD) based on a therapy-oriented severity grading system. BACKGROUND: While mortality is rare after PD, morbidity rates remain high. The lack of standardization in evaluating morbidity after PD has severely hampered meaningful comparisons over time and among centers. We adapted a novel classification of complication to stratify morbidity by severity after PD, to test whether the incidence of pancreatic fistula has changed over time, and to identify risk factors in a single North American center. METHODS: The classification was applied to a consecutive series of 633 patients undergoing PD between February 2003 and August 2005. Another series of 141 patients treated between 1987 and 1990 was also analyzed to identify changes in the incidence and severity of fistula. Univariate and multivariate analyses were performed to link respective complications with preoperative and intraoperative parameters, length of hospital stay, and long-term survival. RESULTS: A total of 263 (41.5%) patients did not develop any complication, while 370 (58.5%) had at least one complication; 62 (10.0%) patients had only grade I complications (no need for specific intervention), 192 patients (30.0%) had grade II (need for drug therapy such as antibiotics), 85 patients (13.5%) had grade III (need for invasive therapy), and 19 patients (3.0%) had grade IV complications (organ dysfunction with ICU stay). Grade V (death) occurred in 12 patients (2.0%). A total of 57 patients (9.0%) developed pancreatic fistula, of which 33 (58.0%) were classified as grade II, 17 (30.0%) as grade III, 5 (9.0%) as grade IV, and 2 (3.5%) as grade V. Delayed gastric emptying was documented in 80 patients (12.7%); half of them were scored as grade II and the other half as grade III. A significant decrease in the incidence of fistula was observed between the 2 periods analyzed (14.0% vs. 9.0%, P < 0.001), mostly due to a decrease in grade II fistula. Cardiovascular disease was a risk factor for overall morbidity and complication severity, while texture of the gland and cardiovascular disease were risk factors for pancreatic fistula. CONCLUSION: This study demonstrates the applicability and utility of a new classification in grading complications following pancreatic surgery. This novel approach may provide a standardized, objective, and reproducible assessment of pancreas surgery enabling meaningful comparison among centers and over time.

Adult↗
PubMed2006

Claudin-4, mitogen-activated protein kinase kinase 4, and stratifin are markers of gastric adenocarcinoma precursor lesions.

Approximately 23,000 new gastric cancer cases and 12,000 associated deaths occur annually in the United States. Intestinal metaplasia and gastric epithelial dysplasia are precursor lesions to gastric adenocarcinoma, but are not readily detectable clinically, radiographically, or endoscopically. A noninvasive method of precursor detection would require the ability to distinguish precursor lesions from adjacent normal mucosa. In search of such markers, tissue microarrays were prepared for 133 patients of resected gastric adenocarcinoma. Tissue microarrays contained primary cancer, normal stomach, intestinal metaplasia, and gastric epithelial dysplasia and were probed with antibodies against nine potential markers that were either identified in a database of genes overexpressed in gastric adenocarcinoma or were already of interest to our laboratory: claudin-4, mitogen-activated protein kinase kinase 4 (MKK4), 14-3-3sigma (stratifin), S100A4, mesothelin, fascin, topoisomerase IIalpha, HER-2/neu, and epithelial growth factor receptor. Three markers discriminated gastric adenocarcinoma precursor lesions from normal gastric mucosa. Claudin-4 expression was present in 36 intestinal metaplasia lesions (100%) and 14 gastric epithelial dysplasia lesions (100%), but in only 16 normal stomach samples (15%). MKK4 expression was present in 24 intestinal metaplasia lesions (89%) and 12 gastric epithelial dysplasia lesions (100%), but in only 6 normal stomach samples (8%). Stratifin expression was present in 29 intestinal metaplasia lesions (97%) and 8 gastric epithelial dysplasia lesions (100%), but in only 2 normal stomach samples (3%). Sensitivity and specificity for detection of the precursor lesion intestinal metaplasia were 100% and 85%, respectively, for claudin-4; 89% and 92%, respectively, for MKK4; and 97% and 97%, respectively, for stratifin. In primary cancers, 123 of 125 (98.4%) were positive for claudin-4, 116 of 126 (94%) for MKK4, and 111 of 120 (92%) for stratifin. In conclusion, claudin-4, MKK4, and stratifin immunolabeling detects precursor lesions of gastric adenocarcinoma that are otherwise clinically, radiographically, and endoscopically inapparent. These findings may prove useful in the diagnosis and therapeutic targeting of gastric adenocarcinoma precursor lesions.

14-3-3 Proteins↗
PubMed2006

Beverage-agarose gel electrophoresis: an inquiry-based laboratory exercise with virtual adaptation.

A wide range of literature and experience has shown that teaching methods that promote active learning, such as inquiry-based approaches, are more effective than those that rely on passive learning. Gel electrophoresis, one of the most common laboratory techniques in molecular biology, has a wide range of applications in the life sciences. As such, we chose it as a platform to expose high school and undergraduate students to the active process of scientific inquiry in general, while specifically teaching electrophoresis. First, we optimized DNA electrophoresis in the laboratory by using common beverages instead of standard media (e.g., Tris-based media). Second, we adapted this laboratory process of progressive optimization to a Web-based format in which students had to achieve all the same steps of optimization by performing serial electrophoreses. And third, we evaluated the use of this entirely Web-based virtual laboratory exercise in high school and undergraduate biology courses. Students learned fundamental and practical principles of electrophoresis, while experiencing the essential inquiry-based process of optimizing a technique, and they also enjoyed it. Our findings provide a readily accessible, inexpensive, and intriguing technique for teaching electrophoresis and the progressive optimization of a laboratory technique.

Beverages↗
PubMed2005

In vivo therapeutic responses contingent on Fanconi anemia/BRCA2 status of the tumor.

PURPOSE: BRCA2, FANCC, and FANCG gene mutations are present in a subset of pancreatic cancer. Defects in these genes could lead to hypersensitivity to interstrand cross-linkers in vivo and a more optimal treatment of pancreatic cancer patients based on the genetic profile of the tumor. EXPERIMENTAL DESIGN: Two retrovirally complemented pancreatic cancer cell lines having defects in the Fanconi anemia pathway, PL11 (FANCC-mutated) and Hs766T (FANCG-mutated), as well as several parental pancreatic cancer cell lines with or without mutations in the Fanconi anemia/BRCA2 pathway, were assayed for in vitro and in vivo sensitivities to various chemotherapeutic agents. RESULTS: A distinct dichotomy of drug responses was observed. Fanconi anemia-defective cancer cells were hypersensitive to the cross-linking agents mitomycin C (MMC), cisplatin, chlorambucil, and melphalan but not to 5-fluorouracil, gemcitabine, doxorubicin, etoposide, vinblastine, or paclitaxel. Hypersensitivity to cross-linking agents was confirmed in vivo; FANCC-deficient xenografts of PL11 and BRCA2-deficient xenografts of CAPAN1 regressed on treatment with two different regimens of MMC whereas Fanconi anemia-proficient xenografts did not. The MMC response comprised cell cycle arrest, apoptosis, and necrosis. Xenografts of PL11 also regressed after a single dose of cyclophosphamide whereas xenografts of genetically complemented PL11(FANCC) did not. CONCLUSIONS: MMC or other cross-linking agents as a clinical therapy for pancreatic cancer patients with tumors harboring defects in the Fanconi anemia/BRCA2 pathway should be specifically investigated.

Animals↗
PubMed2005

Novel genotoxicity assays identify norethindrone to activate p53 and phosphorylate H2AX.

Norethindrone is a commonly used drug for contraception and hormone replacement therapy, whose carcinogenic potential is still controversial. We applied a novel and particularly sensitive method to screen for DNA damage with special attention to double-strand breaks (DSBs) and identified norethindrone to be likely genotoxic and therefore potentially mutagenic: a p53-reporter assay served as a first, high-throughput screening method and was followed by the immunofluorescent detection of phosphorylated H2AX as a sensitive assay for the presence of DSBs. Norethindrone at concentrations of 2-100 microg/ml activated p53 and phosphorylated H2AX specifically and in a dose-dependent manner. No p53 activation or H2AX phosphorylation was detected using a panel of structurally/functionally related drugs. The overall amount of DNA damage induced by norethindrone was low as compared with etoposide and ionizing radiation. Consistently, norethindrone treatment did not cause a cell cycle arrest. DSBs were not detected with the neutral comet assay, a less sensitive method for DSB assessment than H2AX phosphorylation. Our findings in the p53-reporter and gamma-H2AX assays could not be ascribed to common DSB-causing artifacts in standard genotoxicity screening, including drug precipitation, high cytotoxicity levels and increased apoptosis. Therefore, our study suggests that norethindrone induces DSBs in our experimental setting, both complementing and adding a new aspect to the existing literature on the genotoxic potential of norethindrone. As the effective concentrations of norethindrone used in our assays were approximately 100- to 1000-fold higher than therapeutical doses, the significance of these findings with regard to human exposure still remains to be determined.

Animals↗
PubMed2005

The cholinesterase inhibitor, phenserine, improves Morris water maze performance of scopolamine-treated rats.

Male Fischer-344 rats (n = 38) at 5 months old were tested in a Morris water maze to determine if treatment with the cholinesterase inhibitor, phenserine (PHEN), would overcome a learning impairment induced by scopolamine (SCOP), a muscarinic cholinergic receptor antagonist. Each rat was randomly assigned to one of five groups to receive two intraperitoneal injections 60 and 30 min, prior to testing, respectively, as follows: (1) saline-saline (SAL); (2) saline-1.0 mg/kg (SCOP); (3) 2 mg/kg PHEN- SCOP (PHEN2); (4) 4 mg/kg PHEN-SCOP (PHEN4); and (5) 1 mg/kg PHEN-SAL (PHEN1). Maze testing occurred across 5 days with 4 days of acquisition trials (4 trials per day) and a fifth day consisting of a single 120 sec probe trial. PHEN1 and SAL were combined into one control (CON) group for purposes of statistical analysis for both acquisition and probe trials as comparison of the two groups revealed that they did not significantly differ on any measure. SCOP-treated rats were significantly impaired compared to CON in learning the location of the submerged platform as measured by latency to locate the platform and the distance traversed to find the platform across days of testing. The PHEN4 group had significantly lower latencies and traveled a shorter distance to reach the submerged platform when compared to SCOP on the fourth day of trials while the PHEN2 group traveled more directly to the submerged platform but did not have shorter latencies than the SCOP group. For probe trials, CON rats swam closer to the target area (a measure of proximity to the removed platform) than did all other groups, and the PHEN4 group swam in an area more proximate to the target area than did the SCOP-treated group. These findings demonstrate the ability of this drug to improve learning when cholinergic function has been impaired in a spatial memory task.

Animals↗
PubMed2005

Neutropenic enterocolitis in adults: case series and review of the literature.

Necrotizing enterocolitis in adults is a rare disease and, in the past, has been associated with nearly uniform mortality. In recent years, necrotizing enterocolitis, now termed neutropenic enterocolitis, in adults has become more prevalent as a complication of aggressive systemic chemotherapy. In this report, we discuss two cases of neutropenic enterocolitis secondary to the administration of systemic chemotherapy in adult cancer patients: one with lung carcinoma, the other with leukemia. Both patients were successfully treated with early surgical intervention for resection of all necrotizing enteric lesions, and subsequent aggressive critical care support. Our experience suggests that early surgical intervention in adult patients with intestinal necrosis due to chemotherapy is essential to avoid mortality from this condition. Given the widespread, aggressive use of systemic chemotherapy in the neoadjuvant setting, patients at risk for this potentially lethal complication of neutropenic enterocolitis are increasingly common.

Aged↗
PubMed2005

Small-bowel diverticulosis.

Diffuse jejunoileal diverticulosis with pneumoperitoneum but without peritonitis is an uncommon but well-documented entity. Cases of jejunoileal diverticular perforation in which the perforation is evident are managed with resection of the diseased bowel and primary anastomosis. In the absence of an intraoperative finding of a perforation or an area of discrete inflammation, copious irrigation and closure of the abdomen is appropriate in cases of diffuse small-bowel diverticulosis.

Abdominal Pain↗
PubMed2004

Necrotizing soft tissue infection from decubitus ulcer after spinal cord injury.

STUDY DESIGN: A case of necrotizing soft tissue infection in a patient with spinal cord injury with extension of infection into the spinal canal and spinal cord is presented. OBJECTIVE: To review the history, risk factors, pathophysiology, diagnosis, treatment, and morbidity and mortality regarding necrotizing soft tissue infection as they relate to spinal cord injury. SUMMARY OF BACKGROUND DATA: Necrotizing soft tissue infection related to decubitus ulcers is rare. To our knowledge, this is the first report of this disease related to a sacral decubitus ulcer with extension of the necrotizing infection into the spinal canal. METHODS: The clinical, radiographic, and pathologic features associated with necrotizing soft tissue infection are presented. The patient presented with a late-stage necrotizing soft tissue infection requiring extensive de-bridement of necrotic tissue, which the patient underwent on admission. RESULTS: The patent died of refractory septic shock and multiple-organ failure after surgery. CONCLUSION: Necrotizing soft tissue infections from decubitus ulcers are rare and unpredictable, and ultimately have a progressively aggressive course. The case reported herein is the first report of necrotizing soft tissue infection from a decubitus ulcer in a patient with spinal cord injury with extension into the spinal canal and spinal cord.

Abdomen↗