Biomedical subjects

M D Duncan

Publications and source records attributed to M D Duncan.

18 recordsLinked to original sources

PubMed2004

Electroporative transfection with KGF-1 DNA improves wound healing in a diabetic mouse model.

We recently demonstrated that electroporation enhances transfection in a mouse wound-healing model. Keratinocyte growth factor (KGF) is an inducer of epithelial cell proliferation and differentiation and has been shown to be under expressed in the wounds of diabetic individuals. We hypothesized that KGF delivered into an excisional wound via naked DNA injection with subsequent electroporation would be a novel and potentially effective method to enhance wound closure in a diabetic mouse model. ELISA assays confirmed production of KGF protein in cultured mouse cells and RT-PCR assays confirmed KGF mRNA in skin samples taken from mice. In all, 32 genetically diabetic mice were given two identical excisional wounds of their dorsum and split into two groups with one group receiving KGF DNA injection and electroporation with the other group receiving no treatment. Over 90% of wounds healed in the presence of KGF and electroporation versus 40% in the untreated group by day 12. Histological analysis of the wounds demonstrated that untreated wounds contained microulcers with thin or incomplete epithelium with unresolved inflammation as compared to treated wounds where intact and mature epithelium was observed. Taken together these findings suggest that a single injection of KGF DNA encoded on a plasmid coupled with electroporation improves and accelerates wound closure in a delayed wound-healing model.

Animals↗

PubMed2001

Acidic fibroblast growth factor overexpression partially protects 3T3 fibroblasts from apoptosis induced by synthetic retinoid CD437.

Retinoids are proapoptotic compounds with therapeutic potential for treating cancer. We evaluated the apoptotic effect of the novel retinoid CD437, and particularly its relationship to Akt and acidic fibroblast growth factor (aFGF). We hypothesized that the novel synthetic retinoid CD437 would exert its apoptotic effect by reducing the activity of Akt. We further hypothesized that aFGF would protect against CD437 apoptosis by preserving the activity of Akt. Initially we demonstrated that CD437 produces apoptotic cell death in NIH 3T3 fibroblasts, and that this effect is attenuated in fibroblasts transfected to express aFGF. Next we assessed Akt activity and showed that phospho-Akt is significantly reduced in 3T3 cells exposed to CD437. We showed that this effect is less pronounced in aFGF transfected 3T3 cells. Furthermore, we observed that the addition of exogenous aFGF to 3T3 cells significantly increases Akt phosphorylation. These findings tend to confirm our hypothesis that reduction in Akt activation is a mechanism involved in the apoptotic effect of the retinoid CD437, and that preservation of Akt phosphorylation occurs in response to aFGF and appears to explain the partially protective effect of aFGF for 3T3 cells vis a vis CD437.

3T3 Cells↗

PubMed2000

Management of Barrett's esophagus.

There have been major recent advances in the understanding of the pathogenesis and epidemiology of Barrett's esophagus and adenocarcinoma of the esophagus. The advent of potent acid suppression with proton pump inhibitors and safe, minimally invasive antireflux procedures has made alleviating symptoms and eliminating peptic complications achievable goals for the vast majority of patients. Endoscopic surveillance of Barrett's esophagus is considered the standard of care and is widely used in clinical practice. Neither medical nor surgical antireflux procedures, however, result in the regression of Barrett's esophagus in any consistent manner. Thermal and chemical endoscopic ablation techniques show promise in both the management of high grade dysplasia and the reversal of Barrett's esophagus, but these techniques are still of unproven benefit, and can be costly and risky. Therefore, prospective and controlled studies with long term follow-up are needed before incorporating ablative techniques into routine clinical practice. Management of high grade dysplasia remains controversial. Alternative management strategies include surveillance, resection or ablation, tailored to the individual patient and the available expertise. Targets for future research include defining appropriate surveillance intervals; finding biological markers that identify patients at higher risk of progressing to cancer; defining the cancer risk and the appropriate management of patients with short segment Barrett's esophagus; understanding the natural history of dysplasia and comparing alternatives for the management of high grade dysplasia; and studying whether surgical management can delay or prevent the progression to dysplasia and adenocarcinoma.

Adenocarcinoma↗

PubMed1999

Utility of magnetic resonance cholangiography in the evaluation of biliary obstruction.

BACKGROUND: Evaluation of suspected biliary obstruction has traditionally involved a variety of imaging modalities including ultrasound, CT, and invasive cholangiography. These techniques have limitations because of poor visualization of intraductal stones (ultrasound and CT) and the need for an invasive procedure (ERCP and percutaneous transhepatic cholangiography). Magnetic resonance cholangiography (MRC) is a noninvasive imaging modality that provides good visualization of the hepatobiliary system. The aim of the present study was to determine the utility of MRC in evaluating patients with suspected biliary obstruction. STUDY DESIGN: One hundred forty-three patients were identified with suspected acute biliary obstruction and underwent MRC. Patient selection was based on clinical criteria including an elevation in serum liver chemistries or evidence of biliary ductal dilatation on conventional imaging. MRC was performed using a half-Fourier acquisition single-shot turbo spin-echo sequence involving single breath-hold rapid image acquisition. A final diagnosis was determined in each patient based on invasive cholangiography, findings at surgery, and clinical course. RESULTS: Of the 143 patients, 73 had an obstructing biliary lesion. A malignant process was identified in 25 patients with final diagnoses of pancreatic cancer (n = 15), ampullary cancer (n = 4), cholangiocarcinoma (n = 3), and hepatic or nodal metastases (n = 3). MRC correctly identified biliary obstruction in all these patients and accurately identified the level of biliary obstruction in 24 of 25 patients. Based on the MRC images alone, a malignant process was suspected in 21 of the 25 patients. Forty patients were found to have common bile duct stones and eight patients had a benign distal bile duct stricture. MRC correctly identified common bile duct stones in 37 patients with one false-positive exam (sensitivity = 92%; specificity = 99%). MRC also correctly identified distal biliary strictures in eight patients. In the remaining 70 patients, no definite biliary obstruction was identified by MRC, and in all patients the absence of mechanical obstruction was confirmed by invasive cholangiography or overall clinical course. CONCLUSIONS: This study demonstrates that MRC is able to accurately identify the level and cause of biliary obstruction in both malignant and benign disease. MRC may prove to be an important noninvasive tool in preoperative evaluation of patients with suspected biliary obstruction and identification of patients most likely to benefit from an invasive radiologic or surgical procedure.

Adolescent↗

PubMed1999

Hospital volume can serve as a surrogate for surgeon volume for achieving excellent outcomes in colorectal resection.

OBJECTIVE: To examine the association of surgeon and hospital case volumes with the short-term outcomes of in-hospital death, total hospital charges, and length of stay for resection of colorectal carcinoma. METHODS: The study design was a cross-sectional analysis of all adult patients who underwent resection for colorectal cancer using Maryland state discharge data from 1992 to 1996. Cases were divided into three groups based on annual surgeon case volume--low (< or =5), medium (5 to 10), and high (>10)--and hospital volume--low (<40), medium (40 to 70), and high (> or =70). Poisson and multiple linear regression analyses were used to identify differences in outcomes among volume groups while adjusting for variations in type of resections performed, cancer stage, patient comorbidities, urgency of admission, and patient demographic variables. RESULTS: During the 5-year period, 9739 resections were performed by 812 surgeons at 50 hospitals. The majority of surgeons (81%) and hospitals (58%) were in the low-volume group. The low-volume surgeons operated on 3461 of the 9739 total patients (36%) at an average rate of 1.8 cases per year. Higher surgeon volume was associated with significant improvement in all three outcomes (in-hospital death, length of stay, and cost). Medium-volume surgeons achieved results equivalent to high-volume surgeons when they operated in high- or medium-volume hospitals. CONCLUSIONS: A skewed distribution of case volumes by surgeon was found in this study of patients who underwent resection for large bowel cancer in Maryland. The majority of these surgeons performed very few operations for colorectal cancer per year, whereas a minority performed >10 cases per year. Medium-volume surgeons achieved excellent outcomes similar to high-volume surgeons when operating in medium-volume or high-volume hospitals, but not in low-volume hospitals. The results of low-volume surgeons improved with increasing hospital volume but never equaled those of the high-volume surgeons.

Aged↗

PubMed1998

Characterization of an aFGF gene expression vector with therapeutic potential.

BACKGROUND: Topical application of growth factors to wounds has proven to be suboptimal in achieving epithelial growth and accelerating healing. We propose transfection of fibroblasts with a gene for acidic fibroblast growth factor (aFGF) which will allow continuous, local delivery of the growth factor to wounds, ulcerative lesions, or healing tissues. METHODS: We utilized a pMEXneo vector containing the human aFGF gene with a secretory signal sequence from the hst/KS3 gene to obtain continuous secretion of therapeutic doses of aFGF. NIH 3T3 fibroblasts were transfected using a liposomal transfection reagent and grown in selective media. RESULTS: Dot blot hybridization with labeled complementary DNA probes revealed the presence of plasmid DNA in transfected but not wild type fibroblasts. Intracellular concentrations of aFGF remained low in transfected cells; however, the media contained high levels (32 +/- 7 nM) of aFGF as measured by ELISA. Concentrations of aFGF capable of stimulating cell proliferation were maintained for several weeks. CONCLUSIONS: The aFGF cDNA was transcribed and translated into a functional polypeptide that is secreted from NIH 3T3 cells at physiologically significant concentrations. Stable transfection with a eukaryotic vector which induces secretion of aFGF at levels promoting cell growth holds promise for clinical application in wounds or healing tissue. Transfection could be achieved by topical or endoscopic injection of this type of vector.

3T3 Cells↗

PubMed1998

Role of insulin-like growth factor-I in esophageal mucosal healing processes.

The current study examines the stimulation of healing processes and signal transduction that is mediated by insulin-like growth factor-I (IGF-I) in an ex vivo esophageal explant model when using tyrphostin inhibition of receptor tyrosine kinase. The explant model provides a 3-dimensional cellular environment of multiple interacting cells isolated from the neural and vascular supply. Tyrphostins previously characterized for their interactions with epithelial growth factor (EGF) receptor-associated protein tyrosine kinases were tested for their potential effects on IGF-I growth-promoting activity. Explants of rabbit esophagus were incubated in media with or without IGF-I. Tyrphostins 1, 23, 25, 46, 47, 51, and 63 were added. We assessed DNA synthesis by tritiated thymidine incorporation. Outgrowth from the edge of the primary mucosa of the explant was evaluated on histologic sections, and cell proliferation was confirmed with immunohistology. IGF-I increased the incorporation of tritiated thymidine by 50% to 100%. Tyrphostins 23 and 47 eliminated IGF-I-induced proliferation in a dose-dependent manner. Tyrphostins 25, 46, and 51--along with negative controls tyrphostin 1 and tyrphostin 63--were ineffective, inasmuch as IGF-I-stimulated growth remained unchanged in their presence. Proliferative activity demonstrated by PCNA staining was confined to new mucosa. Two of 5 tyrphostins originally developed as EGF receptor protein tyrosine kinase inhibitors were effective in inhibiting the actions of exogenous IGF-I. We conclude that IGF-I stimulation may play an important role in repair processes in the esophagus and that this stimulation can be inhibited by using specific tyrphostins.

Animals↗

PubMed1997

Cucurbitacin E targets proliferating endothelia.

Tumor vasculature offers a target for drugs directed against proliferating endothelia. We hypothesized that cucurbitacin E (CuE), an actin-disrupting agent, would preferentially inhibit proliferating vs. quiescent endothelia. Log-phase and confluent ECV304 and HUVEC human endothelial cells were exposed to 10-200 nM CuE for 1-96 hr, and toxicity was determined at 2-6 days by sulforhodamine B assay. Confluent ECV cells were scraped by Q-tip to allow proliferation at the margin and exposed to CuE at LD50, and the actin cytoskeleton was stained by rhodamine-phalloidin. Cell cycle analysis was performed by flow cytometry. Log-phase cells were significantly inhibited compared to confluent. LD50's of log-phase cells were much less than for confluent cells (12 vs. 170 nM, ECV; 13 vs 76 nM, HUVEC). Persistent growth inhibition required 24-96 hr exposure to LD50. Followed less than 6 hr exposure. CuE induced F-actin to accumulate centrally in clumps in newly proliferating cells; actin appeared normal in quiescent cells. CuE treated endothelial cells were not blocked at cytokinesis. CuE preferentially potently inhibits proliferating human endothelia compared to quiescent cells in vitro. CuE induces depolymerization of F-actin in proliferating cells. At low concentrations, cucurbitacin E may potently inhibit vascular proliferation by disrupting actin.

Actins↗

PubMed1997

EGF and IGF-I synergistically stimulate proliferation of human esophageal epithelial cells.

Proliferation of esophageal mucosal cells is important in repair of reflux-induced injury. We studied the effects of EGF, IGF-I, and IGF-I/binding protein-3 (BP-3) complex on immortalized esophageal epithelial (HET-1A) cells and searched for synergy between the growth factors. HET-1A cells were plated at 5 x 10(4) in 12 well plates. After 2 days in optimal media, they were maintained in basal media with or without the test peptides: EGF at 0.05-5 nM, IGF-I at 0.1-10 nM, IGF-I/BP-3 at 0.1-10 nM, and a combination of EGF at 5 nM and IGF-I or IGF-I/BP-3 at 1 and 10 nM. In comparison to basal media EGF and IGF-I stimulated cell proliferation over baseline at 5 and 10 nM, respectively. The combination of EGF at 5 nM and IGF-I at 1 and 10 nM worked synergistically, increasing cell counts over baseline to 10.3 +/- 0.2 and 14.6 +/- 0.8 x 10(5), respectively. The calculated additive effect of EGF and IGF-I at 1 and 10 nM individually increased cell counts to 8.2 +/- 0.2 and 10.4 +/- 0.6 x 10(5), respectively. The difference between the observed and the calculated values was significant at P < 0.05, ANOVA, Turkey test. IGF-I/BP-3 complex enhanced this synergy at low levels of IGF-I but not at 10 nM IGF-I. EGF, IGF, and IGF-I/BP-3 independently promote HET-1A proliferation. IGF and EGF in combination demonstrate synergism with potentiated interaction presumably because of their different roles in the cell cycle, EGF being a competence factor and IGF being a progression factor. This combination may have potential as a treatment for esophageal mucosal injury, and IGF-I/BP-3 may further enhance their benefit.

Cell Cycle↗

PubMed1996

Cucurbitacin E-induced disruption of the actin and vimentin cytoskeleton in prostate carcinoma cells.

Cucurbitacin E has been identified by an empiric screening strategy as a sterol with potent growth inhibitory activity in vitro directed against prostate carcinoma explants (IC50 of 7-50 nM in 2- to 6-day exposures). The mechanism of cucurbitacin cytoxicity has not been elucidated previously. In the present study, we observed that cucurbitacin E caused marked disruption of the actin cytoskeleton, and in a series of cucurbitacin analogues, anti-proliferative activity correlated directly with the disruption of the F-actin cytoskeleton. The distribution of vimentin was also altered in cells exposed to cucurbitacin E, as vimentin associated with drug-induced membrane blebs. The appearance of microtubules was unaffected. Western blot analysis of intracellular actin in cells exposed to cucurbitacins and quantitation of rhodamine-phalloidin binding support the hypothesis that cucurbitacin treatment leads to an inappropriate increase in the filamentous or polymerized actin fraction in prostate carcinoma cells. We conclude that cucurbitacins are potent disruptors of cytoskeletal integrity. Prostate carcinoma cells appear notably sensitive to growth inhibition by cucurbitacin E.

Actins↗

PubMed1996

Actin disruption inhibits bombesin stimulation of focal adhesion kinase (pp125FAK) in prostate carcinoma.

UNLABELLED: Jasplakinolide is a member of a new class of antitumor agents targeting the actin cytoskeleton with activity against prostate cancer. Focal adhesion kinase (FAK) is an actin-associated mediator of mitogenic peptides. We hypothesized that the neuropeptide bombesin would activate FAR in prostate carcinoma, and that disruption of the actin network would block FAK activation and inhibit cell growth. METHODS: PC-3 human prostate carcinoma cells were exposed to 50-200 nM jasplakinolide (Jas) or cytochalasin E (CyE) in cytotoxicity experiments. FAK phosphorylation was measured in cells stimulated with 0.01-10 nM bombesin; separate cells were pretreated 6 hr with 50-500 nM Jas or CyE. Cell lysates and anti-FAK immunoprecipitates were subjected to SDS-PAGE, Western blotting, and detection with anti-actin or anti-phosphotyrosine. Depolymerized G-actin was separated from total actin by ultracentrifugation. Cytoskeletal changes were confirmed by fluorescence microscopy. RESULTS: Jas (GI50 = 47 +/- 7 nM) and CyE (GI50 61 +/- 20 nM) potently inhibited PC-3 growth (P < 0.01 vs control). Bombesin rapidly stimulated tyrosine phosphorylation of FAK in a dose dependent manner. FAK phosphorylation was inhibited to near-basal levels (50% of bombesin stimulated) by 500 nM Jas (63%) and 500 nM CyE (61%). CONCLUSIONS: Bombesin stimulated FAK in prostate carcinoma cells. Jasplakinolide, which induced over-polymerization of actin, and CyE, which depolymerizes actin, both inhibited bombesin-stimulated phosphorylation of FAK and inhibited PC-3 cell growth. Actin-disrupting agents block FAK signal transduction, which may be critical to their antitumor activity in prostate carcinoma.

Actins↗

PubMed1994

Epidermal growth factor primes intestinal epithelial cells for proliferative effect of insulin-like growth factor I.

Insulin-like growth factor I (IGF-I) synergistically enhances epidermal growth factor (EGF)-stimulated proliferation of intestinal epithelial cells. A possible mechanism of this synergy is that EGF acts as a "competence" factor increasing the fraction of proliferating cells by promoting transition from G0 to G1, thus allowing IGF-I, a "progression" factor, to act as a proliferative agent on the cycling population. Consistent with this hypothesis would be temporally distinct actions wherein initial brief exposure to EGF would permit synergy, whereas pretreatment with IGF-I would not. Rat intestinal epithelial cells of the IEC-18 crypt cell line were serum-deprived, then treated with EGF (5 x 10(-9) M), IGF-I (5 x 10(-9) M), or insulin (2 x 10(-6) M) for a 30-min pulse and then media containing EGF, IGF-I, insulin, or no factor was substituted for 48 hr. IGF-I and EGF each stimulated enterocyte proliferation; together they synergistically promoted cell growth. A brief pulse of IGF-I neither induced cell proliferation nor enhanced the EGF effect. Initial brief exposure to EGF, however, was equally efficacious as continuous exposure and allowed full synergy with IGF-I. Insulin at supraphysiologic levels acted similarly to IGF-I. Thus, EGF acted as a competence factor priming the cells for subsequent action by IGF-I. The cell kinetic parameters of these growth factors may be important to both physiologic and pathologic enterocyte growth regulation.

Analysis of Variance↗

PubMed1993

Extracellular matrix composition influences insulinlike growth factor I receptor expression in rat IEC-18 cells.

BACKGROUND: The composition of the extracellular matrix (ECM) as well as insulinlike growth factor I (IGF-I) receptor density vary along the crypt-villus axis. We determined whether components of the ECM influence IGF-I receptor expression in IEC-18 rat small intestine crypt cells. METHODS: IEC-18 cells were cultured on plastic, collagen type IV, Matrigel, and laminin at the plateau and proliferative growth phases. Receptor affinity (Kd) and number (Bmax) were determined by competitive binding of 125I-IGF-I in the presence of increasing concentrations of unlabeled IGF-I. Receptor isolation was performed by affinity cross linking. Messenger RNA (mRNA) for IGF-I receptor was quantified by Northern analysis. RESULTS: Specific binding of IGF-I > IGF-II > insulin was observed. A 130,000-molecular weight protein was identified by cross-linking, consistent with the alpha subunit of the IGF-I receptor. Scatchard analysis revealed no effect of ECM on IGF-I binding affinity. In contrast, the Bmax was 18% lower for plateau-phase cells cultured on Matrigel vs. plastic and was 42% lower for cells cultured on laminin vs. collagen type IV. The Bmax for proliferative growth phase cells was decreased when cultured on Matrigel vs. plastic and was 10-fold less than for cells cultured at the plateau growth phase. Northern analysis revealed that IEC-18 cells cultured on Matrigel had less mRNA for IGF-I receptor than cells cultured on plastic. CONCLUSIONS: The rate of cell proliferation and the composition of the ECM influence IGF-I receptor expression in IEC-18 cells.

Animals↗

PubMed1991

Advantages of handsewn over stapled bowel anastomosis.

Bowel anastomoses are conventionally performed using a handsewn technique or a stapling device. Each has potential benefits and disadvantages. The most clinically significant complications of the bowel anastomosis are anastomotic leakage and stricture formation. The indices of healing and tissue cohesion were compared dynamically over time in 24 dogs randomized to undergo either a standard two-layer handsewn anastomosis or a stapled anastomosis with the Premium CEEA (United States Surgical Corporation, Norwalk, CT). Animals were sacrificed at 1, 4, 7, and 28 days postoperatively. Each anastomosis was evaluated for anastomotic index, burst pressure, collagen content, and histologic appearance. The anastomotic index was similar on postoperative day (POD) 1, 4, and 7; but on day 28 all handsewn anastomoses had larger diameters than the widest CEEA anastomosis. Burst pressure was higher in handsewn anastomoses at all intervals. Collagen content tended to be higher on POD 7 in the CEEA anastomoses. Histological evaluation showed more complete epithelialization and less inflammation in handsewn anastomoses on POD 28. The higher level of collagen in the CEEA anastomoses on POD 7 may be implicated in the tendency toward stricture formation found with this type of anastomosis. This study demonstrates that the greater speed and ease of the stapled anastomosis is offset by the greater strength, reduced tendency to stricture, and more complete healing of the handsewn anastomosis.

Anastomosis, Surgical↗

PubMedDate not supplied

Esophagogastric adenocarcinoma in an E1A/E1B transgenic model involves p53 disruption.

We studied tumorigenesis and p53 immunostaining in a murine transgenic model introducing E1A/E1B under the control of the mouse mammary tumor virus-long terminal repeat (MMTV-LTR) promoter in which adenocarcinoma occurs at the squamocolumnar junction in the foregut, predominantly in males, and at no other site. Mutations of p53 are frequent in human esophageal adenocarcinoma and the E1B gene product interferes with p53-mediated apoptosis, inhibiting tumor suppression at the G(1)/S checkpoint. Transgenic animals were generated utilizing a purified linear 6.7 kb fragment of plasmid DNA containing MMTV-LTR/E1A/E1B and were confirmed by dot blot hybridization of tail DNA to (32)P-labeled E1A/E1B probe and polymerase chain reaction (PCR) amplification of E1A. Transgenic and control animals were observed for morbidity and weight changes. Eleven of 45 animals were transgenic (24% efficiency) with an estimated 5 to 57 copies of the gene per genome. Profound weight loss (>20%) led to sacrifice or death of one of five females (at 12 weeks) and four of six males (at 16 to 17 weeks). Grossly visible tumors (2 to 10 mm) were noted in the forestomach at the visible margin between the proximal (squamous-lined) stomach and the distal glandular stomach. Histologic sections confirmed adenocarcinoma arising in each case at the squamocolumnar junction with glandular formation, pleomorphism, and frequent mitotic figures. Immunostaining was positive for p53 indicating accumulation of mutated or altered p53 protein. E1A/E1B transgenic animals developed macroscopic and microscopic adenocarcinoma at the squamocolumnar junction, which corresponds to adenocarcinoma at the human esophagogastric junction. Disruption of p53 was present in the transgenic model as in the human cancer.

Adenocarcinoma↗

PubMedDate not supplied

Success and limitations of a naked plasmid transfection protocol for keratinocyte growth factor-1 to enhance cutaneous wound healing.

Our group and others have previously reported enhancement of cutaneous wound healing following the transfection of tissue with plasmid vectors expressing the DNA for growth factors. In these experiments, growth factor treated animals were usually compared to animals treated with control plasmid vector. To achieve consistent transfection, high DNA plasmid load and repeated penetrations of the wound by needle or gene gun were required. In the current experiments, we assessed the effect of the plasmid load and repeated tissue penetrations on wound healing of excisional wounds in diabetic C57 mice. Animals received 5 mm excisional wounds, and were assigned to the following groups, no treatment, phosphate buffered saline solution injections, and plasmid vector injection with and without the keratinocyte growth factor-1 gene. Intradermal injections of 100 microg plasmid were given adjacent to the wounds at days 1-5, 7 and 11. At day 9, wound closure was more advanced in keratinocyte growth factor-1 treated animals compared to those treated with control plasmid. But a detrimental effect of the DNA plasmid injection was evident from a comparison of the DNA control group versus the non-injected group. Therefore, the challenge for developing an effective system for the enhancement of wound healing lies in improving transfection efficiency.

Animals↗

PubMedDate not supplied

Evidence of androgen receptor expression in squamous and adenocarcinoma of the esophagus.

Androgen receptors (AR) are known to stimulate cellular proliferation in certain tumors. We have assessed the androgen receptor status of esophageal carcinoma in surgically resected specimens as well as in established human esophageal carcinoma cells lines. In these initial studies we sought to characterize the frequency of expression of androgen receptors in squamous versus adenocarcinoma and in male versus female patients, and to assess the possible influence of AR expression on survivaL We analyzed androgen receptor expression utilizing immunohistochemistry in adenocarcinoma and squamous cell carcinoma of the esophagus in surgical specimens from 25 patients treated at Johns Hopkins Bayview Medical Center. Tumors in 7 of 21 males (33%) and 1 of 4 females (25%) showed positive androgen receptor staining with the monoclonal body antibody AR 441. There was no suggestion of a difference in expression of AR between males and females. Five of 11 adenocarcinomas (45%) and 3 of 14 squamous carcinomas were positive. Survival was similar in AR+ and AR- patients. Studies with established tissue culture cell lines showed AR expression by RT-PCR, with stronger expression of AR in adenocarcinoma lines than in squamous carcinoma lines. The presence of AR in human esophageal cancer is an impetus for further studies to assess anti-androgen therapy for treatment and or prevention of these tumors.

Adenocarcinoma↗

PubMedDate not supplied

Synthetic retinoid CD437 induces apoptosis of esophageal squamous HET-1A cells through the caspase-3-dependent pathway.

6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (AHPN/CD437) is a novel retinoid that has shown to be a potent inducer of apoptosis in cancer cells. We investigated the apoptosis-inducing activity of CD437 and its mechanism of action in the human esophageal squamous epithelial cell line (HET-1A). CD437 decreased HET-1A cell viability in a time and dose dependent manner. CD437 was found to induce DNA fragmentation. Apoptosis was accompanied by markedly increased activity of caspase-3 as well expression of caspase-3 and -8 and APRP fragmentation. The CD437-mediated activation of caspase-3 was inhibited by Z-DEVD-FMK These data indicate that CD437-induced apoptosis in HET-1A cells may be mediated through the caspase-3 dependent pathway. In addition, apoptosis was also accompanied by increased expression of Bad protein and down-regulation of Bcl-2 expression. Phosphorylation of Jun occurred following CD437 exposure indicating that Jun kinase (JNK) activity was strongly induced by CD437. Understanding these apoptotic pathways of esophageal epithelial cells may allow therapeutic induction of cell death in malignant orpremalignant lesions of the esophagus by agents such as CD437.

Antineoplastic Agents↗