R. Daniel Beauchamp

Claudin-1 regulates cellular transformation and metastatic behavior in colon cancer

Disruption of the cell-cell junction with concomitant changes in the expression of junctional proteins is a hallmark of cancer cell invasion and metastasis. The role of adherent junction proteins has been studied extensively in cancer, but the roles of tight junction (TJ) proteins are less well understood. Claudins are recently identified members of the tetraspanin family of proteins, which are integral to the structure and function of TJs. Recent studies show changes in expression/cellular localization of claudins during tumorigenesis; however, a causal relationship between claudin expression/localization and cancer has not been established. Here, we report an increased expression of claudin-1 in human primary colon carcinoma and metastasis and in cell lines derived from primary and metastatic tumors. We also report frequent nuclear localization of claudin-1 in these samples. Genetic manipulations of claudin-1 expression in colon cancer cell lines induced changes in cellular phenotype, with structural and functional changes in markers of epithelial-mesenchymal transition. Furthermore, we demonstrate that changes in claudin-1 expression have significant effects on growth of xenografted tumors and metastasis in athymic mice. We further provide data suggesting that the regulation of E-cadherin expression and beta-catenin/Tcf signaling is a possible mechanism underlying claudin-1-dependent changes.

Epidermal growth factor-related peptides and their relevance to gastrointestinal pathophysiology

Growth factor biology has been one of the most exciting areas of gastroenterological research in recent years. Although many fundamental questions about growth factors and their relevance to the gastrointestinal tract remain unanswered and unexplored, the available data point to major clinical significance in a large number of gastrointestinal disorders. This report reviews the biology and significance of the epidermal growth factor (EGF) family, with particular emphasis on understanding the integrated function of the family and the relationships between family members in the context of gastrointestinal physiology and pathophysiology.

Experimentally Derived Metastasis Gene Expression Profile Predicts Recurrence and Death in Patients With Colon Cancer

BACKGROUND & AIMS Staging inadequately predicts metastatic risk in patients with colon cancer. We used a gene expression profile derived from invasive, murine colon cancer cells that were highly metastatic in an immunocompetent mouse model to identify patients with colon cancer at risk of recurrence. METHODS This phase 1, exploratory biomarker study used 55 patients with colorectal cancer from Vanderbilt Medical Center (VMC) as the training dataset and 177 patients from the Moffitt Cancer Center as the independent dataset. The metastasis-associated gene expression profile developed from the mouse model was refined with comparative functional genomics in the VMC gene expression profiles to identify a 34-gene classifier associated with high risk of metastasis and death from colon cancer. A metastasis score derived from the biologically based classifier was tested in the Moffitt dataset. RESULTS A high score was significantly associated with increased risk of metastasis and death from colon cancer across all pathologic stages and specifically in stage II and stage III patients. The metastasis score was shown to independently predict risk of cancer recurrence and death in univariate and multivariate models. For example, among stage III patients, a high score translated to increased relative risk of cancer recurrence (hazard ratio, 4.7; 95% confidence interval, 1.566-14.05). Furthermore, the metastasis score identified patients with stage III disease whose 5-year recurrence-free survival was >88% and for whom adjuvant chemotherapy did not increase survival time. CONCLUSION A gene expression profile identified from an experimental model of colon cancer metastasis predicted cancer recurrence and death, independently of conventional measures, in patients with colon cancer.

Nonoperative management of primary colorectal cancer in patients with stage IV disease.

Background: Traditional teaching maintains that patients with primary colorectal adenocarcinoma require timely resection to prevent bleeding, perforation, or obstruction. The true benefits of primary tumor resection remain undocumented for patients presenting with metastatic disease, however. We postulated that resection of primary colorectal tumors could be avoided safely in a select population of asymptomatic colorectal cancer patients presenting with incurable stage IV disease.Methods: A retrospective review of the Vanderbilt University Hospital tumor registry was performed for the years 1985 to 1997. During this period, 955 patients presented for management of primary colorectal cancer. From this group, all patients with stage IV disease at the time of diagnosis were identified. Patients who initially underwent resection of their primary lesion were included in the resection group; those who underwent initial nonoperative primary tumor management were included in the nonresection group. Data were obtained regarding age, extent of disease, nonsurgical therapy, tumor-specific complications, and palliative surgical procedures. Surgery-free survival and overall survival were analyzed using the Kaplan-Meier method. For patients with liver metastases, hepatic tumor burden was defined as either H1 (<25% parenchymal replacement), H2 (25% to 50%), or H3 (>50%) disease.Results: Sixty-six patients were included in the resection group, and 23 patients with intact asymptomatic primary colorectal lesions were included in the nonresection group. Among patients with hepatic metastases, most of the patients in both groups had H1 disease. Ten patients in the resection group and 3 patients in the nonresection group presented with exclusively extrahepatic metastases. In the nonresection group, primary therapy included chemotherapy in 13 patients, external beam radiation therapy in 1 patient, and combination chemoradiation in 9 patients. The median survival in the nonresection group was 16.6 months. The 2-year actuarial survival was 18%, and the surgery-free survival was 91.3%. Only 2 of 23 patients (8.7%) managed without resection eventually developed obstruction at the primary tumor site requiring emergent diversion. There were no episodes of tumor-related hemorrhage or perforation. For the resection group, the operative morbidity was 30.3%, and the perioperative mortality rate was 4.6%. The median survival in the resection group was 14.5 months (P = 0.59, log-rank test vs. nonresection group).Conclusions: Selected patients with asymptomatic primary colorectal tumors who present with incurable metastatic disease may safely avoid resection of their primary lesions, with an anticipated low rate of hemorrhage, perforation, or obstruction before death from systemic disease. No survival advantage is gained by resection of an asymptomatic primary lesion in the setting of incurable stage IV colorectal cancer.

Regulation of Cyclooxygenase-2 Expression by the Translational Silencer TIA-1

The cyclooxygenase-2 (COX-2) enzyme catalyzes the rate-limiting step of prostaglandin formation in inflammatory states, and COX-2 overexpression plays a key role in carcinogenesis. To understand the mechanisms regulating COX-2 expression, we examined its posttranscriptional regulation mediated through the AU-rich element (ARE) within the COX-2 mRNA 3′-untranslated region (3′UTR). RNA binding studies, performed to identify ARE-binding regulatory factors, demonstrated binding of the translational repressor protein TIA-1 to COX-2 mRNA. The significance of TIA-1-mediated regulation of COX-2 expression was observed in TIA-1 null fibroblasts that produced significantly more COX-2 protein than wild-type fibroblasts. However, TIA-1 deficiency did not alter COX-2 transcription or mRNA turnover. Colon cancer cells demonstrated to overexpress COX-2 through increased polysome association with COX-2 mRNA also showed defective TIA-1 binding both in vitro and in vivo. These findings implicate that TIA-1 functions as a translational silencer of COX-2 expression and support the hypothesis that dysregulated RNA-binding of TIA-1 promotes COX-2 expression in neoplasia.

Eastern Cooperative Oncology Group Phase I Trial of Protracted Venous Infusion Fluorouracil Plus Weekly Gemcitabine With Concurrent Radiation Therapy in Patients With Locally Advanced Pancreas Cancer: A Regimen With Unexpected Early Toxicity

PURPOSE We performed a phase I trial of protracted venous infusion (PVI) fluorouracil (5-FU) plus weekly gemcitabine with concurrent radiation therapy in patients with locally advanced pancreas cancer to determine the maximum-tolerated dose of gemcitabine that could be safely administered. We also sought to identify the toxicities associated with this treatment protocol. PATIENTS AND METHODS Seven patients with locally advanced pancreas cancer were treated with planned doses of radiation (59.4 Gy) and PVI of 5-FU (200 mg/m(2)/d) with gemcitabine doses of 50 to 100 mg/m(2)/wk. RESULTS Two of three patients at the 100-mg/m(2)/wk dose level experienced dose-limiting toxicity (DLT), as did three of four at the 50-mg/m(2)/wk dose level. One patient experienced a mucocutaneous reaction described as a Stevens-Johnson syndrome that was attributed to chemotherapy. Three patients developed gastric or duodenal ulcers with severe bleeding requiring transfusion. One patient developed severe thrombocytopenia lasting longer than 4 weeks. Three of the five episodes of DLT developed at radiation doses < or = 36 Gy. CONCLUSION Based on this experience, we cannot recommend further investigation of regimens incorporating gemcitabine into regimens of radiation with PVI 5-FU. The mechanism of this synergistic toxicity remains to be determined.

Resident Work Hour Limits and Patient Safety

Objective:This study evaluates the effect of resident physician work hour limits on surgical patient safety. Background:Resident work hour limits have been enforced in New York State since 1998 and nationwide from 2003. A primary assumption of these limits is that these changes will improve patient safety. We examined effects of this policy in New York on standardized surgical Patient Safety Indicators (PSIs). Methods:An interrupted time series analysis was performed using 1995 to 2001 Nationwide Inpatient Sample data. The intervention studied was resident work hour limit enforcement in New York teaching hospitals. PSIs included rates of accidental puncture or laceration (APL), postoperative pulmonary embolus or deep venous thrombosis (PEDVT), foreign body left during procedure (FB), iatrogenic pneumothorax (PTX), and postoperative wound dehiscence (WD). PSI trends were compared pre- versus postintervention in New York teaching hospitals and in 2 control groups: New York nonteaching hospitals and California teaching hospitals. Results:A mean of 2.6 million New York discharges per year wereanalyzed with cumulative events of 33,756 (APL), 36,970 (PEDVT), 1,447 (FB), 10,727 (PTX), and 2,520 (WD). Increased rates over time (expressed per 1000 discharges each quarter) were observed in both APL (0.15, 95% confidence interval, 0.09–0.20, P<0.05) and PEDVT (0.43, 95% confidence interval, 0.03–0.83, P<0.05) after policy enforcement in New York teaching hospitals. No changes were observed in either control group for these events or New York teaching hospital rates of FB, PTX, or WD. Conclusions:Resident work hour limits in New York teaching hospitals were not associated with improvements in surgical patient safety measures, with worsening trends observed in APL and PEDVT corresponding with enforcement.

Molecular detection of micrometastatic breast cancer in histopathology-negative axillary lymph nodes correlates with traditional predictors of prognosis: An interim analysis of a prospective multi-institutional cohort study

Objective:We sought to establish the clinical relevance of micrometastatic disease detected by reverse transcription polymerase chain reaction (RT-PCR) in axillary lymph nodes (ALN) of breast cancer patients. Background:The presence of ALN metastases remains one of the most valuable prognostic indicators in women with breast cancer. However, the clinical relevance of molecular detection of micrometastatic breast cancer in sentinel lymph nodes (SLN) and nonsentinel ALN has not been established. Methods:Four hundred eighty-nine patients with T1–T3 primary breast cancers were analyzed in a prospective, multi-institutional cohort study. ALN were analyzed by standard histopathology (H&E staining) and by multimarker, real-time RT-PCR analysis (mam, mamB, muc1, CEA, PSE, CK19, and PIP) designed to detect breast cancer micrometastases. Results:A positive marker signal was observed in 126 (87%) of 145 subjects with pathology-positive ALN, and in 112 (33%) of 344 subjects with pathology-negative ALN. In subjects with pathology-negative ALN, a positive marker signal was significantly associated with traditional indicators of prognosis, such as histologic grade (P = 0.0255) and St. Gallen risk category (P = 0.022). Mammaglobin was the most informative marker in the panel. Conclusion:This is the first report to show that overexpression of breast cancer–associated genes in breast cancer subjects with pathology-negative ALN correlates with traditional indicators of disease prognosis. These interim results provide strong evidence that molecular markers could serve as valid surrogates for the detection of occult micrometastases in ALN. Correlation of real-time RT-PCR analyses with disease-free survival in this patient cohort will help to define the clinical relevance of micrometastatic disease in this patient population.

Inhibition of pancreatic adenocarcinoma cell growth by lovastatin

RAS protein (p21 ras) requires farnesyl (an intermediate of cholesterol synthesis) for activation. Activating mutations of K-ras gene have been detected in most human pancreatic adenocarcinomas. In the present study, the effect of lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A, the rate-limiting enzyme of cholesterol synthesis, on the growth of five pancreatic cancer cell lines (human-CAV, MIA Paca2, CAPAN2 and PANC1, and hamster-H2T) in vitro and of two cell lines (CAV and H2T) in vivo was examined. Inhibition of cell growth was observed with lovastatin doses at or above 2.5 micrograms/mL for H2T, CAV, MIA Paca2, and CAPAN2 or 10 micrograms/mL in PANC1. The H2T cell line was studied further to determine the reversibility of growth inhibition. Mevalonic acid (1 mmol/L) reversed lovastatin-induced inhibition of cell growth if it was added with lovastatin (2.5 micrograms/mL). Similarly, removal of lovastatin from the medium within 24 hours after treatment allowed recovery of cell growth. The effect of lovastatin on cell growth was irreversible after 48 hours of exposure. The survival fraction of H2T cells was markedly decreased by 1- or 24-hour exposure to 75 micrograms/mL but not to doses ranging from 0.5 to 60 micrograms/mL of lovastatin. Growth of pancreatic carcinoma xenografts (CAV and H2T) in nude mice was inhibited by a subcutaneous infusion of lovastatin (50 micrograms/h). These results indicate that mevalonic acid or a metabolite in the cholesterol synthesis pathway is necessary for growth of pancreatic cancer cells and suggest that lovastatin should be further examined as a potential therapeutic agent for pancreatic cancer.

Loss of Rab25 promotes the development of intestinal neoplasia in mice and is associated with human colorectal adenocarcinomas

Transformation of epithelial cells is associated with loss of cell polarity, which includes alterations in cell morphology as well as changes in the complement of plasma membrane proteins. Rab proteins regulate polarized trafficking to the cell membrane and therefore represent potential regulators of this neoplastic transition. Here we have demonstrated a tumor suppressor function for Rab25 in intestinal neoplasia in both mice and humans. Human colorectal adenocarcinomas exhibited reductions in Rab25 expression independent of stage, with lower Rab25 expression levels correlating with substantially shorter patient survival. In wild-type mice, Rab25 was strongly expressed in cells luminal to the proliferating cells of intestinal crypts. While Rab25-deficient mice did not exhibit gross pathology, ApcMin/+ mice crossed onto a Rab25-deficient background showed a 4-fold increase in intestinal polyps and a 2-fold increase in colonic tumors compared with parental ApcMin/+ mice. Rab25-deficient mice had decreased beta1 integrin staining in the lateral membranes of villus cells, and this pattern was accentuated in Rab25-deficient mice crossed onto the ApcMin/+ background. Additionally, Smad3+/- mice crossed onto a Rab25-deficient background demonstrated a marked increase in colonic tumor formation. Taken together, these results suggest that Rab25 may function as a tumor suppressor in intestinal epithelial cells through regulation of protein trafficking to the cell surface.