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Biomedical subjects

Lee M Ellis

Publications and source records attributed to Lee M Ellis.

At least 73 records · Page 4Linked to original sources

ZD6474, a vascular endothelial growth factor receptor tyrosine kinase inhibitor with additional activity against epidermal growth factor receptor tyrosine kinase, inhibits orthotopic growth and angiogenesis of gastric cancer.

Vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF) have been strongly implicated in the growth and metastasis of gastric cancer. The purpose of this study was to examine the effects of ZD6474, an inhibitor of inhibitor of VEGF receptor (VEGFR) tyrosine kinase with additional activity against EGF receptor (EGFR), on tumor growth and angiogenesis in an orthotopic model of gastric cancer. In vitro, ZD6474 inhibited human umbilical vascular endothelial cell and TMK-1 human gastric tumor cell proliferation in a dose-dependent fashion. EGF-mediated activation of EGFR and Erk-1/2 was decreased in tumor cells after ZD6474 treatment. In addition, VEGF-mediated activation of VEGFR2 and Erk-1/2 was decreased in human umbilical vascular endothelial cells. TMK-1 human gastric adenocarcinoma cells were injected into the gastric wall of nude mice. ZD6474 therapy was initiated on day 10. Mice (n = 14 per group) were treated p.o. with (a) 1% Tween 80 (control), (b) 50 mg/kg/d ZD6474, or (c) 100 mg/kg/d ZD6474. Mice were sacrificed on day 33. Tumors from each group were stained for markers of blood vessels, pericytes, proliferation, and apoptosis. ZD6474 at both 50 and 100 mg/kg/d led to marked inhibition of tumor growth (P < 0.05). ZD6474 reduced tumor cell proliferation by 48% in the 50 mg/kg/d group and 65% in the 100 mg/kg/d group (P < 0.03) and increased tumor cell apoptosis (P < 0.001) in vivo. ZD6474 led to a 69% decrease in microvessel density in the 50 mg/kg/d group (P < 0.001) and a 62% decrease in the 100 mg/kg/d group (P < 0.001). Although microvessel density was decreased by ZD6474, the remaining vessels showed a relatively higher percentage of pericyte coverage (3-fold increase; P < 0.001), perhaps reflecting selective loss of uncovered vessels in the ZD6474 group. In conclusion, therapies such as ZD6474 that target two distinct aspects of tumor growth, angiogenesis and tumor cell proliferation, warrant further investigation.

Angiogenesis Inhibitors↗

Vascular endothelial growth factor receptors: expression and function in solid tumors.

Vascular endothelial growth factor (VEGF) and its family members are important mediators of tumor angiogenesis. The multiple functions of the VEGF are mediated through complex and selective interactions between the ligands, their high-affinity tyrosine kinase receptors, and co-receptors (neuropilins). While these receptors are historically described as being exclusively expressed on endothelial cells, emerging evidence has documented expression of these receptors on a number of nonendothelial cells, including tumor cells. The VEGF receptors (VEGFR) have also been shown to be functional in a number of nonendothelial systems, where they may be targets for anti-VEGF therapy. This article will review the basic effects and interactions of the VEGFRs on endothelial cells and the evidence for their expression and function on tumor cells. The novel expression of VEGFRs on tumor cells contributes to the understanding of the complex roles of VEGF within the tumor microenvironment, potentially affecting both endothelial cells and tumor cells expressing the VEGFRs. This elucidation of VEGF activity may further refine antineoplastic regimens for solid malignancies.

Angiogenesis Inhibitors↗

Expression and regulation of the novel vascular endothelial growth factor receptor neuropilin-1 by epidermal growth factor in human pancreatic carcinoma.

BACKGROUND: It was recently shown that neuropilin-1 (NRP-1), which was described originally as a receptor for the semaphorins/collapsins (ligands involved in neuronal guidance), is a coreceptor for vascular endothelial growth factor (VEGF) and increases the affinity of specific isoforms of VEGF to its receptor, VEGF-R2. METHODS: The authors investigated the expression and regulation of NRP-1 in human pancreatic adenocarcinoma specimens and cell lines. RESULTS: Immunohistochemical analysis revealed that NRP-1 was expressed in 12 of 12 human pancreatic adenocarcinoma specimens but was absent in nonmalignant pancreatic tissue. Northern blot analysis revealed NRP-1 mRNA expression in 8 of 11 human pancreatic adenocarcinoma cell lines. NRP-1 mRNA expression was increased by epidermal growth factor (EGF) but not by tumor necrosis factor alpha in several of the human pancreatic adenocarcinoma cell lines studied. Treating human Panc-48 adenocarcinoma cells with EGF activated Akt and Erk but not P-38. Blockade of the phosphatidylinositol-3 kinase (PI-3K)/Akt, mitogen-activated protein kinase (MAPK)/Erk, or P-38 pathways abrogated EGF-induced NRP-1 expression. Finally, EGF receptor blockade in vivo led to a decrease in NRP-1 expression in an orthotopic model of human pancreatic carcinoma. CONCLUSIONS: NRP-1 is expressed in most human pancreatic adenocarcinomas and cell lines but not in nonmalignant pancreatic tissue. EGF regulates NRP-1 expression through the PI-3K/Akt and MAPK/Erk signaling pathways, and blockade of the EGF receptor is associated with decreased expression of NRP-1 in vivo. NRP-1 may act as a coreceptor for VEGF in pancreatic carcinoma, as it does in other tumor systems, thereby enhancing angiogenesis and the effect of VEGF on the growth of pancreatic adenocarcinoma.

Adenocarcinoma↗

Cyclooxygenase-2 is up-regulated by interleukin-1 beta in human colorectal cancer cells via multiple signaling pathways.

Overexpression of cyclooxygenase-2 (COX-2) has been observed in human colorectal cancer. COX-2 expression in human tumors can be induced by growth factors, cytokines, oncogenes, and other factors. The mechanisms regulating COX-2 expression in human colon cancer have not been completely elucidated. We hypothesized that the proinflammatory cytokine interleukin-1 beta (IL-1 beta) mediates COX-2 expression in HT-29 human colon cancer cells. Treatment of HT-29 cells with IL-1 beta induced expression of COX-2 mRNA and protein in a time- and dose-dependent manner. Inhibitors of the extracellular signal-regulated kinase 1/2, c-Jun NH(2)-terminal kinase, P38 mitogen-activated protein kinase, and nuclear factor-kappa B (NF-kappa B) signaling pathways blocked the ability of IL-1 beta to induce COX-2 mRNA. In contrast, Wortmannin, a phosphoinositide 3-kinase inhibitor upstream of protein kinase B/Akt, led to a slight increase in COX-2 mRNA expression after IL-1 beta treatment. Electrophoretic mobility shift assay on nuclear extracts demonstrated that IL-1 beta induced NF-kappa B DNA binding activity in HT-29 cells, and the activated NF-kappa B complex was eliminated after treatment with an inhibitor of NF-kappa B. Supershift assay indicated that the two NF-kappa B subunits, p65 and p50, were involved in activation of NF-kappa B complex by IL-1 beta stimulation. The stability of COX-2 mRNA was not altered by IL-1 beta treatment. These data demonstrate that IL-1 beta induces COX-2 expression in HT-29 cells through multiple signaling pathways and NF-kappa B.

Colonic Neoplasms↗

Angiopoietin-1 inhibits vascular permeability, angiogenesis, and growth of hepatic colon cancer tumors.

Angiopoietin (Ang)-1 and -2 are critical regulators of embryonic and postnatal neovascularization. Ang-1 activates the endothelial cell-specific tyrosine kinase receptor Tie-2, which in turn leads to enhanced endothelial cell survival and stabilization. The effects of Ang-1 on tumor angiogenesis remain controversial; although we have previously demonstrated that Ang-1 overexpression in colon cancer cells leads to a decrease in s.c. tumor growth, others have shown that Ang-1 may be proangiogenic. Few studies have addressed the role of the Angs in tumors growing in the organ of metastatic growth. We hypothesized that overexpression of Ang-1 may inhibit the growth of colon cancers growing in the liver by inhibition of angiogenesis. We also wanted to investigate the mechanisms by which Ang-1 affects angiogenesis in vivo. Human colon cancer cells (HT29) were stably transfected with an Ang-1 construct or an empty vector (pcDNA) and injected directly into the livers of nude mice. After 37 days, livers were harvested and weighed, and tumor sizes were measured. In an additional experiment, to validate the paracrine effect of Ang-1, various mixtures of control cells and Ang-1-transfected cells were injected into livers, and tumor growth was assessed. Direct effects of recombinant Ang-1 on angiogenesis were studied with an in vivo Gelfoam angiogenesis assay. The impact of Ang-1 on vascular permeability was investigated using an intradermal Miles assay with conditioned media from transfected cells. Liver weights (P < 0.05), tumor volumes (P < 0.05), vessel counts (P < 0.01), and tumor cell proliferation (P < 0.01) in the Ang-1 group were significantly lower than those in the control (pcDNA) group. Tumor vessels in the Ang-1 group developed a significantly higher degree of pericyte coverage (P < 0.02) than vessels in pcDNA tumors. In the cell mixture experiment, even as few as a 1:10 mixture of Ang-1-transfected cells/control cells resulted in a significant reduction of hepatic tumor volumes (P < 0.04). In the angiogenesis assay, vessel counts in Gelfoam implants were significantly decreased by the addition of Ang-1 (P < 0.01). Finally, conditioned medium from Ang-1-transfected cells decreased vascular permeability more than that from control cells (P < 0.05). Our results suggest that Ang-1 is an important regulator of angiogenesis and vascular permeability and that this effect may be secondary to increasing periendothelial support and vessel stabilization. Thus, Ang-1 could potentially serve as an antineoplastic or anti-permeability agent for patients with metastatic colorectal cancer.

Angiogenesis Inducing Agents↗

Down-regulation of c-Met inhibits growth in the liver of human colorectal carcinoma cells.

Overexpression of c-Met, the protein tyrosine kinase receptor for the hepatocyte growth factor/scatter factor, has been implicated in the progression and metastasis of human colorectal carcinoma. To examine the role of c-Met on in vitro and in vivo growth of human colon tumor cell lines, stable subclones of the high metastatic human colorectal carcinoma cell line, KM20, isolated from a Dukes' D patient, with reduced c-Met expression were obtained after transfection with a c-Met-specific targeting ribozyme. The subclones were only modestly reduced in c-Met expression because of c-Met playing an important role in cellular survival. However, a 60-90% reduction in basal c-Met autophosphorylation and kinase activity were observed. Correlating with the reduction in c-Met kinase activity, subclones with reduced c-Met expression had significantly reduced in vitro growth rates and soft-agar colony-forming abilities. The in vivo growth of these cells was examined at both the ectopic SQ site and the orthotopic site of metastatic growth, the liver. SQ growth was delayed significantly in the c-Met down-regulated clones compared with controls, with tumors growing on loss of the ribozyme construct. In contrast, tumor incidence was significantly reduced when the c-Met down-regulated cells were grown in the orthotopic liver site. Thus, c-Met activation may be important in metastatic growth of colon tumor cells in the liver. Collectively these data demonstrate that a small reduction in c-Met protein levels leads to profound biological effects, and potential c-Met inhibitors may be of therapeutic value in treatment of colon cancer.

Adenoviridae↗

Alphavbeta3 integrin antagonist S247 decreases colon cancer metastasis and angiogenesis and improves survival in mice.

Members of the integrin family influence several aspects of tumor progression and metastasis, including cell survival, proliferation, and angiogenesis. Specific integrins such as alpha(v)beta(3) and alpha(v)beta(5) are involved in regulating endothelial cell function, and thus angiogenesis. We evaluated the effect of the alpha(v)beta(3)/alpha(v)beta(5) integrin antagonist S247 on the growth and angiogenesis of colon cancer liver metastases in an orthotopic murine model. Murine colon cancer cells were injected into the spleens of BALB/c mice to produce liver metastases. On day 7, miniature osmotic pumps were implanted into the subcutis to continuously infuse either saline or 70 mg/kg/day S247. All mice were sacrificed when control mice became moribund. Mice that received S247 developed significantly fewer liver metastases than did controls (P < 0.05). Using the same model, a subsequent survival study was performed. Mice were sacrificed when moribund as determined by an observer blinded to the treatment given. Treatment with S247 significantly prolonged overall survival (P < 0.05). Interestingly, primary tumors in the spleen were the cause of death in the S247-treated group as S247 appeared to have little effect on these tumors. Immunohistochemical staining demonstrated a significant reduction of vessels in liver metastases of S247-treated mice (P < 0.001), a significant increase in endothelial cell apoptosis (P < 0.05), and a significant decrease in pericyte coverage (P < 0.0001). To determine the role of S247 on angiogenesis, we examined the effect of S247 in vitro on human umbilical vein endothelial cells (HUVECs) and human vascular smooth muscle cells (hVSMCs). The addition of S247 to HUVECs and hVSMCs growing on vitronectin-coated flasks and in Matrigel significantly impaired cell growth and colony formation, respectively (P < 0.05). Furthermore, S247 completely inhibited the attachment of HUVECs and hVSMCs and increased apoptosis by six- to 9fold compared with controls. In in vitro invasion assays, S247-treated cells demonstrated decreased migration (P < 0.05). In conclusion, S247 demonstrated significant antimetastatic and antiangiogenic activity and impaired both endothelial and hVSMC/pericyte function in vitro and in vivo. The use of agents such as integrin antagonists that target multiple cell types involved in angiogenesis may be a more effective method of inhibiting angiogenesis than agents targeting only the endothelial cells.

Angiogenesis Inhibitors↗

Inhibition of integrin alpha5beta1 function with a small peptide (ATN-161) plus continuous 5-FU infusion reduces colorectal liver metastases and improves survival in mice.

Integrin alpha(5)beta(1) is expressed on activated endothelial cells and plays a critical role in tumor angiogenesis. We hypothesized that a novel integrin alpha(5)beta(1) antagonist, ATN-161, would inhibit angiogenesis and growth of liver metastases in a murine model. We further hypothesized that combining ATN-161 with 5-fluorouracil (5-FU) chemotherapy would enhance the antineoplastic effect. Murine colon cancer cells (CT26) were injected into spleens of BALB/c mice to produce liver metastases. Four days thereafter, mice were given either ATN-161 (100 mg/kg, every 3rd day) or saline by intraperitoneal injection, with or without combination of continuous-infusion 5-FU (100 mg/kg/2 weeks), which was started on day 7. On day 20 after tumor cell inoculation, mice were killed and liver weights and number of liver metastases were determined. A follow-up study on survival was also conducted in which mice were randomized to receive ATN-161, 5-FU or ATN-161+5-FU. Combination therapy with ATN-161+5-FU significantly reduced tumor burden (liver weight) and number of liver metastases (p<0.02). Liver tumors in the ATN-161 and ATN-161+5-FU groups had significantly fewer microvessels (p<0.05) than tumors in the control or 5-FU-treated groups. Unlike treatment with either agent alone, ATN-161+5-FU significantly increased tumor cell apoptosis and decreased tumor cell proliferation (p<0.03) and improved overall survival (p<0.03, log-rank test). Targeting integrin alpha(5)beta(1) in combination with 5-FU infusion reduced liver metastases formation and improved survival in this colon cancer model. The enhancement of antineoplastic activity from the combination of anti-angiogenic therapy and chemotherapy may be a promising approach for treating metastatic colorectal cancer.

Angiogenesis Inhibitors↗

Biology of angiogenesis in tumors of the gastrointestinal tract.

The realization that the growth and spread of tumors are dependent on angiogenesis has created new avenues of research designed to help us to better understand cancer biology and to facilitate the development of new therapeutic strategies. However, the process of angiogenesis consists of multiple, sequential, and interdependent steps with a myriad of positive and negative regulators of angiogenesis being involved. The survival of tumors and thus their metastases are dependent upon the balance of endogenous angiogenic and anti-angiogenic factors such that the outcome favors increased angiogenesis. Several growth factors have been identified that regulate angiogenesis in cancers of the gastrointestinal tract. These include pro-angiogenic factors like vascular endothelial growth factor (VEGF) and anti-angiogenic factors, i.e., thrombospondin. The following review provides a brief overview about the most important factors that are involved in the angiogenic process in tumors derived from colon, stomach, and pancreas. A thorough understanding of the role these factors play in the angiogenic process may lead to the development of novel therapeutic antineoplastic strategies.

Angiogenesis Inhibitors↗

Phase II trial of systemic continuous fluorouracil and subcutaneous recombinant interferon Alfa-2b for treatment of hepatocellular carcinoma.

PURPOSE: Because cirrhosis is extremely common in hepatocellular carcinoma (HCC) in the United States, and it precludes the use of several chemotherapy agents, this phase II trial of fluorouracil (FU) and recombinant interferon alfa-2b (rIFNalpha2b) in HCC was launched with the assumption that it could be tolerated by cirrhotics. PATIENTS AND METHODS: Forty-three patients with HCC (34), and fibrolamellar HCC (FLHCC; nine) were treated with continuous intravenous (IV) FU (200 mg/m2/d x 21 every 28 days) and subcutaneous (SC) rIFNalpha2b (4 million U/m2) three times weekly. Survival was determined in all 43 patients, and response could be assessed in 28 HCC and 8 FLHCC patients. RESULTS: The median ages of the patients were 63.5 and 19 years among HCC and FLHCC patients, respectively. Liver cirrhosis was present among 71% of HCC patients but among none of the FLHCC patients. Nine of 36 (25%; four of 28 [14%] HCC patients; five of eight [62.5%] FLHCC patients) patients in which a response could be assessed had a complete response (CR; one patient with FLHCC and no patients with HCC) or partial response (PR; eight patients [four HCC and four FLHCC patients]). Four HCC patients underwent resection, and two had a histologic CR; one HCC patient with a PR underwent orthotopic liver transplantation. One FLHCC patient also underwent resection without clear margins. Overall median survival was 19.5 months (95% confidence interval [CI], 11.2 to 27.8 months); median survival was 15.5 months (95% CI, 8.5 to 22.5 months) among HCC patients, and that of FLHCC patients was 23.1 months (95% CI, 10.3 to 35.9 months). Overall grade 3 or 4 toxicity included stomatitis (32.6%), fatigue (4.7%), and hematologic toxicity (9.3%). CONCLUSION: Continuous IV FU and thrice-weekly SC rIFNalpha2b are an effective treatment, especially for FLHCC, and may have a neoadjuvant role in this disease. This regimen has activity in HCC and can be tolerated even by cirrhotic patients.

Adolescent↗

Response to preoperative chemoradiation increases the use of sphincter-preserving surgery in patients with locally advanced low rectal carcinoma.

BACKGROUND: Although controversial, some believe that preoperative chemoradiation increases the use of sphincter-preserving surgery in low rectal carcinoma patients. This article investigates the relationship between objective tumor response and sphincter preservation in low rectal carcinoma patients. METHODS: The authors reviewed the records of 238 patients with T3 or T4 low rectal carcinoma (< or = 6 cm from the anal verge) who underwent preoperative pelvic chemoradiation (45 Gy/25 fractions/5 weeks, n = 182 or 52.5 Gy/30 fractions/5 weeks, n = 56 with continuous infusion 5-fluorouracil at 300 mg/m(2), Monday to Friday) followed by mesorectal (n = 223) or local excision (n = 15). A logistic regression analysis was used to analyze the influence of objective tumor response (defined as complete clinical response) and other prognostic factors on sphincter preservation. Because degrees of partial response could not be objectively defined retrospectively, the influence of partial response on sphincter preservation could not be evaluated. RESULTS: Overall, 49% of patients (117 of 238) had sphincter-preserving surgery. The clinical complete response rate was 47%. Independent predictors of sphincter preservation included the year of surgery, tumor distance from the anal verge, circumferential tumor involvement, and response to chemoradiation. The sphincter preservation rate increased over the period of the study (from 28% [December 1989 to December 1992] to 44% [January 1993 to December 1996] to 67% [January 1997 to December 2000]). The difference in the rates of sphincter preservation according to response was most striking among patients with tumors 3 cm or less from the anal verge (44% vs. 22%, P = 0.01). The pelvic disease recurrence rate among patients undergoing sphincter-preserving surgery has been less than 10% since January 1993 and was not statistically different between the groups treated from January 1993 to December 1996 and from January 1997 to December 2000. CONCLUSIONS: There has been an increase in the use of sphincter-preserving surgery without an increase in pelvic disease recurrence over the past decade. Although not necessary for sphincter preservation, clinical response to preoperative chemoradiation independently contributed to sphincter-preserving surgery, particularly in patients with low rectal tumors.

Adult↗

Perioperative complications in patients undergoing major liver resection with or without neoadjuvant chemotherapy.

Systemic chemotherapy is used increasingly prior to resection of hepatic colorectal metastases. Previous reports have indicated an increased risk of perioperative complications associated with the use of systemic chemotherapy prior to resection. The purpose of this study was to investigate perioperative complications in patients receiving neoadjuvant systemic chemotherapy consisting of 5-fluorouracil (5-FU) and leucovorin (LV) with or without CPT-11 within 6 months of major liver resection. A retrospective review of 108 patients undergoing major liver resection for colorectal metastases with curative intent from 1997 to 2002 was performed. Patient and tumor characteristics, perioperative parameters, and morbidity and mortality were measured. Forty-seven patients (44%) received no chemotherapy, 27 patients (25%) received systemic 5-FU/LV, and 34 (31%) received systemic 5-FU/LV/CPT-11. A significantly higher number of patients in the group treated with preoperative 5-FU/LV plus CPT-11 had multiple tumors. Patients in this group also tended to have smaller tumors, fewer complications, and a higher R0 margin resection rate, but these findings were not statistically significant. Median blood loss and length of hospital stay were also not significantly different. There were no perioperative deaths. We conclude that the use of fluoropyrimidine-based chemotherapy and CPT-11 prior to major liver resection is not associated with increased morbidity or mortality. It may therefore provide a better therapeutic option, particularly in patients with multiple colorectal metastases.

Adult↗

Regulation of hypoxia-inducible factor-1alpha, vascular endothelial growth factor, and angiogenesis by an insulin-like growth factor-I receptor autocrine loop in human pancreatic cancer.

Activation of the insulin-like growth factor-I receptor (IGF-IR) was recently shown to modulate angiogenesis by up-regulating the expression of vascular endothelial growth factor (VEGF). We hypothesized that inhibiting IGF-IR function would inhibit angiogenesis and growth of pancreatic cancer in vivo and sought to identify major signaling pathways regulated by IGF-IR in pancreatic cancer cells. Human pancreatic cancer cells (L3.6pl) were stably transfected with a dominant-negative form of IGF-IR (IGF-IR DN) or an empty vector (pcDNA). In vitro, IGF-IR DN cells exhibited a decrease in both constitutive and inducible phosphorylation of IGF-IR and Erk1/2. Constitutive expression of nuclear hypoxia-inducible factor-1alpha and secreted VEGF (P < 0.01) protein levels also were significantly lower in IGF-IR DN cells than in pcDNA cells. In vivo, IGF-IR inhibition led to decreases in pancreatic tumor volume and weight, vessel density, and tumor cell proliferation (P < 0.01 for all) and increases in tumor cell apoptosis (P < 0.02). Our results suggest that autocrine activation of the IGF-IR system significantly affects VEGF expression and angiogenesis in human pancreatic cancer. Thus, IGF-IR may be a valid target in the treatment of pancreatic cancer.

Adenocarcinoma↗

Biology of colorectal liver metastases.

The elucidation of the interaction of the tumor and its microenvironment has increased surgeons' understanding of the biologic mechanisms mediating metastases formation. The ability to develop effective biologic therapies will depend on understanding the complex interactions among endothelial cells and tumor cells and on the cytokine cross-talk among all cells within a particular tumor at a particular site. Biologic therapies must be targeted to both the site and the tumor. By the time metastases form, most steps in the metastatic cascade have been completed. Therapy to down-regulate or interrupt the last stages of metastases, proliferation, and angiogenesis and mechanisms to disrupt cell survival signals appear to be the most promising areas of investigation.

Carcinoma↗

Promises and pitfalls of anti-angiogenic therapy in clinical trials.

A significant body of research has implicated the process of angiogenesis in the growth and spread of tumors. Elucidation of the mechanisms of tumor angiogenesis has led to the development of multiple anti-angiogenic agents. However, the perceived differences between the results of preclinical studies and those of early phases of clinical trials have led to questions being asked regarding the efficacy of these agents. There are many reasons for this discrepancy, including difficulties in the appropriate interpretation of preclinical data and clinical trial design. Further insights into the complex process of angiogenesis are essential for the development of effective anti-angiogenic regimens.

Angiogenesis Inhibitors↗