CT imaging of esophageal foreign bodies in children: a pictorial essay.

Foreign body (FB) ingestion is common in children, particularly from 6 months to 3 years of age. As young children may be unable to provide a clinical history and the ingestion is often unwitnessed, imaging plays an important role in diagnosis, predicting outcomes and detecting complications that require surgical intervention. Since 2015, our institution's diagnostic algorithm for suspected airway foreign bodies has included a noncontrast airway FB CT (FB-CT) with the z-axis coverage spanning from the larynx to the proximal segmental bronchi of the lower lung zones. The effective dose of radiation from this FB-CT airway protocol is typically less than 1 mSv, compared to an effective dose of just under 1 mSv to up to 3 mSv for a fluoroscopic esophagram in children under 10 years of age and 1-3 mSv for a routine pediatric CT chest. In using the FB-CT airway protocol at our institution, we observed that esophageal rather than airway FBs were sometimes encountered on these exams. However, the confidence among radiologists for definitively diagnosing an esophageal foreign body on noncontrast CT was variable. Consequently, we created a teaching module of positive cases for our group of 21 pediatric body radiologists to increase their diagnostic confidence. This pictorial essay illustrates our institutional experience and can help others to confidently diagnose esophageal foreign bodies using a dedicated CT foreign body imaging protocol. At a similar radiation dose to a fluoroscopic esophagram, CT provides the additional advantage of an expedited diagnosis without the need for a radiologist on site.

Chest CT for the Diagnosis of Pediatric Esophageal Foreign Bodies.

Foreign body ingestion is a common problem in children. Radiography is the mainstay of imaging, but many radiolucent items go undetected without further imaging by fluoroscopic esophagram. While studies in adults support the use of computed tomography (CT) for esophageal foreign body ingestion, CT has historically not been used in children given the typically higher radiation doses on CT compared with fluoroscopy. In distinction to an esophagram, CT does not require oral contrast nor presence of an onsite radiologist and can be interpreted remotely. At our institution, a dedicated CT protocol has been used for airway foreign bodies since 2015. Given the advantages of CT over esophagram, we retrospectively reviewed institutional radiation dose data from 2017 to 2020 for esophagrams, airway foreign body CT (FB-CT), and routine CT Chest to compare effective doses for each modality. For ages 1+ years, effective dose was lowest using the FB-CT protocol; esophagram mean dose showed the most variability, and was over double the dose of FB-CT for ages 5+ years. Routine CT chest doses were uniformly highest across all age ranges. Given these findings, we instituted a CT foreign body imaging protocol as the first-line imaging modality for radiolucent esophageal foreign body at our institution.

Increased 18F-FDG Uptake Associated With Gastric Banding Surgical Mesh on PET/CT.

Surgical mesh was used in the 1980s and early 1990s for vertical banded gastroplasty as treatment for morbid obesity. This procedure was replaced by the more popular laparoscopic gastric banding in the mid-1990s. Surgical mesh, commonly used in hernioplasty, has been associated with increased F-FDG uptake related to an inflammatory foreign body reaction and is a known cause of false-positive PET scans. We present a case of increased F-FDG uptake related to surgical mesh in a patient who had undergone vertical banded gastroplasty.

Effect of molecular therapeutics on liver regeneration in a murine model.

PURPOSE: Unresectable metastatic colorectal cancer (CRC) can be rendered resectable with systemic chemotherapy in approximately 20% of cases. Most patients with metastatic CRC receive chemotherapy with the addition of targeted therapy with anti-vascular endothelial growth factor (VEGF) or anti-epidermal growth factor receptor (EGFR) antibodies. We sought to determine whether anti-VEGF receptor (VEGFR) or anti-EGFR therapy would impair liver regeneration after partial hepatectomy (PH) in mice. MATERIALS AND METHODS: Mice underwent either 66% PH or sham laparotomy. In the first experiment, mice in the PH group were randomly assigned to receive daily intraperitoneal injections of monoclonal antibodies (MoABs) to murine VEGFR-2 or nonspecific MoABs (control). In the second experiment, mice in the PH group were randomly assigned to receive intraperitoneal injections of antimurine EGFR or nonspecific (control) MoABs. In both experiments, therapy was initiated the day before surgery and continued until the mice were killed on day 5. Livers were collected and processed. RESULTS: Anti-VEGFR-2 therapy slightly impaired liver regeneration and hepatic cell proliferation compared with control. Hematoxylin and eosin staining showed no differences in liver morphology. CD105 staining showed decreased levels of activated endothelium in livers in the VEGFR-2 MoAB group. VEGFR-2 MoAB therapy decreased the levels of the cell cycle regulators cyclin D1 and cyclin D3 and the regenerative cytokine interleukin-6. Anti-EGFR therapy had no effect on liver regeneration or cellular proliferation. CONCLUSION: Anti-VEGFR-2 therapy slightly impaired liver regeneration in this murine model, whereas anti-EGFR therapy had no effect on liver regeneration.

Therapeutic targeting of neuropilin-2 on colorectal carcinoma cells implanted in the murine liver.

BACKGROUND: Neuropilin-2 (NRP2) is a high-affinity kinase-deficient receptor for vascular endothelial growth factor (VEGF) and semaphorin 3F. We investigated its function in human colorectal cancers. METHODS: Immunohistochemistry and immunoblotting were used to assess NRP2 expression levels in colorectal tumors and colorectal cancer cell lines, respectively. HCT-116 colorectal cancer cells stably transfected with short hairpin RNA (shRNAs) against NRP2 or control shRNAs were assayed for proliferation by the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and for activation of the VEGFR1 pathway by immunoblotting. Soft agar assays, Annexin V staining, and Boyden chamber assays were used to examine anchorage-independent growth, apoptosis in response to hypoxia, and cell migration/invasion, respectively, in HCT-116 transfectants. Tumor growth and metastasis were analyzed in mice (groups of 10) injected with shRNA-expressing HCT-116 cells. The effect of in vivo targeting of NRP2 by small interfering RNA (siRNA) on the growth of hepatic colorectal tumors derived from luciferase-expressing HCT-116 cells was assessed by measuring changes in bioluminescence and final tumor volumes. All statistical tests were two-sided. RESULTS: NRP2 expression was substantially higher in tumors than in adjacent mucosa. HCT-116 transfectants with reduced NRP2 levels had reduced VEGFR1 signaling, but proliferation was unchanged. Anchorage-independent growth, survival under hypoxic conditions, and motility/invasiveness were also reduced. In vivo, HCT-116 transfectants with reduced NRP2 demonstrated decreased tumor growth, fewer metastases, and increased apoptosis compared with control cells. Hepatic colorectal tumors in mice treated with NRP2 siRNAs were statistically significantly smaller than those in mice treated with control siRNAs (at 28 days after implantation, mean control siRNAs = 420 mm3, mean NRP2 siRNAs = 36 mm3, NRP2 vs control: difference = 385 mm3, 95% confidence interval = 174 mm3 to 595 mm3, P = .005). CONCLUSION: NRP2 on colorectal carcinoma cells is important for tumor growth and is a potential therapeutic target in human cancers where it is expressed.

Regulation of cyclooxygenase-2 (COX-2) expression in human pancreatic carcinoma cells by the insulin-like growth factor-I receptor (IGF-IR) system.

Both the insulin-like growth factor-I receptor (IGF-IR) and cyclooxygenase-2 (COX-2) are frequently overexpressed in pancreatic cancer. We hypothesized that IGF-IR is directly involved in induction of COX-2 and sought to investigate signaling pathways mediating this effect. Pancreatic cancer cells (L3.6pl) were stably transfected with a dominant-negative receptor (IGF-IR DN) construct or empty vector (pcDNA). Cells were stimulated with IGF-I to determine activated signaling intermediates and induction of COX-2. Signaling pathways mediating COX-2 induction were identified using signaling inhibitors. IGF-I up-regulated COX-2 selectively via the MAPK/(Erk-1/2) pathway. In addition, IGF-IR DN cells showed a marked decrease in constitutive COX-2 and a blunted response to IGF-I. Similarly, treatment with an anti-IGF-IR antibody effectively inhibited IGF-IR and MAPK/Erk activation and decreased COX-2 in parental cells. In conclusion, activation of IGF-IR mediates COX-2 expression in human pancreatic cancer cells.

The development and characterization of a human midgut carcinoid cell line.

PURPOSE: Gastrointestinal neuroendocrine tumors (NET) are rare heterogeneous tumors that hypersecrete neuropeptides. The scarcity of good gastrointestinal NET models has limited the ability to study potential therapeutic agents. We describe and characterize the establishment of a human midgut carcinoid tumor cell line carcinoid tumor 2 (CNDT2). EXPERIMENTAL DESIGN: Tumor cells (CNDT2) were isolated from a liver metastasis from a patient with a primary ileal carcinoid. After 9 weeks in culture, the cells were plated in soft agar, and cells from a single colony were put back in culture (CNDT2.1). Those CNDT2.1 cells were injected s.c. into nude mice. Cells were isolated from a single resultant tumor (CNDT2.5), cultured, and characterized by electron microscopy, reverse transcription-PCR, serotonin enzyme immunoassay, Western blotting, and immunohistochemical analysis for NET markers and potential therapeutic targets. RESULTS: CNDT2 cells grew in monolayers in vitro, formed colonies in soft agar, and formed tumors in mice. Electron microscopy revealed round, pleomorphic, electron-dense neurosecretory granules characteristic of NETs. Tumor xenografts exhibited the appearance of NETs with small "salt-and-pepper" nuclei on H&E staining and chromogranin A, synaptophysin, and CD56 on immunohistochemical staining. CNDT2.5 cells produced serotonin and expressed insulin-like growth factor receptor-I, platelet-derived growth factor receptor-beta, vascular endothelial growth factor receptor-1, cMET, epidermal growth factor receptor, neuropilin-1, and somatostatin receptors 1 to 5. Cytogenetic analysis revealed the presence of deletions at 2p and 6q and numerous translocations. CONCLUSION: The establishment of this human midgut carcinoid tumor cell line may serve as a useful model system for studying cell biology and novel targeted agents in preclinical models.

Overexpression of PDGF-BB decreases colorectal and pancreatic cancer growth by increasing tumor pericyte content.

We hypothesized that overexpression of PDGF-BB in colorectal cancer (CRC) and pancreatic cancer cells would result in increased pericyte coverage of ECs in vivo, rendering the tumor vasculature more resistant to antiangiogenic therapy. We stably transfected the cDNA for the PDGF-B into HT-29 human CRC and FG human pancreatic cancer cells. Surprisingly, when HT-29 or FG parental and transfected cells were injected into mice (subcutaneously and orthotopically), we observed marked inhibition of tumor growth in the PDGF-BB-overexpressing clones. In the PDGF-BB-overexpressing tumors, we observed an increase in pericyte coverage of ECs. Treatment of PDGF-BB-overexpressing tumors with imatinib mesylate (PDGFR inhibitor) resulted in increased growth and decreased total pericyte content compared with those in untreated PDGF-BB-overexpressing tumors. In vitro studies demonstrated the ability of VSMCs to inhibit EC proliferation by approximately 50%. These data show that increasing the pericyte content of the tumor microenvironment inhibits the growth of angiogenesis-dependent tumors. Single-agent therapy targeting PDGF receptor must be used with caution in tumors when PDGFR is not the target on the tumor cell itself.

Targeting of insulin-like growth factor-I receptor with a monoclonal antibody inhibits growth of hepatic metastases from human colon carcinoma in mice.

BACKGROUND: Colorectal carcinomas (CRC) express high levels of insulin-like growth factor-I/II (IGF-I/II) and the receptor (IGF-IR). We hypothesized that selective inhibition of IGF-IR would inhibit hepatic growth of human CRC in mice. METHODS: Human CRC cells were treated in vitro with anti-IGF-IR monoclonal antibody (MoAB) with and without oxaliplatin to assess cytotoxicity. The effect of anti-IGF-IR MoAB on IGF-I-induced vascular endothelial growth factor (VEGF) production in human CRC cells was assessed by Northern blot and ELISA. We injected human CRC cells intrahepatically in nude mice, and then administered anti-IGF-IR MoAB with and without oxaliplatin. We delayed treatment in one group until large hepatic tumors were present. We assessed tumors for apoptosis, proliferation, and angiogenesis. RESULTS: Anti-IGF-IR MoAB and oxaliplatin inhibited CRC cell growth in vitro and combination treatment was even more effective. IGF-I stimulation of CRC cells resulted in significant upregulation of VEGF and this was completely inhibited by pretreatment with anti-IGF-IR MoAB. Anti-IGF-IR MoAB significantly inhibited hepatic growth of tumors in mice. Anti-IGF-IR MoAB plus oxaliplatin led to a significantly greater inhibition of tumor growth. Anti-IGF-IR MoAB plus oxaliplatin was just as effective at inhibiting growth of larger, more advanced liver tumors. Anti-IGF-IR MoAB, alone and in combination with oxaliplatin, led to a significant increase in tumor cell apoptosis, and a significant inhibition of tumor cell proliferation and angiogenesis. CONCLUSIONS: These findings suggest that IGF-IR is a potential target for therapy in patients with advanced CRC.

The role of nitric oxide in mediating tumour blood flow.

Nitric oxide (NO) is a ubiquitous molecule with a myriad of physiological and pathophysiological roles. It has numerous direct and indirect effects on tumour vasculature as both a regulatory and effector molecule. NO affects tumour blood flow through its effects on tumour angiogenesis, vascular tone and vascular permeability, partly via its interaction with vascular endothelial growth factor. In this review, the authors examine the basic tenants of NO biology, the association of NO with tumour progression, and the role NO plays in mediating alterations in vascular functions in tumours.

Regulatory role of c-Met in insulin-like growth factor-I receptor-mediated migration and invasion of human pancreatic carcinoma cells.

Pancreatic carcinoma cells overexpress the insulin-like growth factor-I (IGF-I) receptor (IGF-IR) and the hepatocyte growth factor (HGF) receptor, c-Met, which are both known to mediate tumor cell migration and invasion. We hypothesized that IGF-IR and c-Met cooperate to induce migration and invasion of human pancreatic carcinoma cells and that IGF-I-mediated migration and invasion depend on c-Met. Migration and invasion assays were done with the human pancreatic cancer cell line L3.6pl treated with PBS, IGF-I, HGF, or IGF-I plus HGF. To determine if c-Met is necessary for IGF-IR-mediated migration and invasion, c-Met was down-regulated in L3.6pl cells via adenoviral infection with a c-Met ribozyme before IGF-I treatment. IGF-I and HGF increased cell migration and invasion. Furthermore, IGF-I plus HGF had a greater than additive effect on cell migration and invasion compared with either growth factor alone. Down-regulation of c-Met nearly completely inhibited IGF-I-mediated migration and invasion. Our findings suggest that IGF-IR and c-Met cooperate to induce migration and invasion of human pancreatic carcinoma cells. Furthermore, c-Met is required for both HGF- and IGF-I-mediated migration and invasion. Elucidation of the signaling pathways that contribute to tumor progression and metastasis should provide a foundation for the development of targeted therapies for pancreatic carcinoma.

Chronic oxaliplatin resistance induces epithelial-to-mesenchymal transition in colorectal cancer cell lines.

PURPOSE: Epithelial-to-mesenchymal transition (EMT) is a process whereby cells acquire molecular alterations that facilitate cell motility and invasion. In preliminary studies, we observed that oxaliplatin-resistant (OxR) colorectal cancer (CRC) cells underwent morphologic changes suggestive of a migratory phenotype, leading us to hypothesize that OxR CRC cells undergo EMT. EXPERIMENTAL DESIGN: The human CRC cell lines KM12L4 and HT29 were exposed to increasing doses of oxaliplatin to establish stable cell lines resistant to oxaliplatin. Migration and invasion were assessed by modified Boyden chamber assays. Morphologic and molecular changes characteristic of EMT were determined by immunofluorescence staining and Western blot analyses. RESULTS: The OxR cells showed phenotypic changes consistent with EMT: spindle-cell shape, loss of polarity, intercellular separation, and pseudopodia formation. KM12L4 and HT29 OxR cells exhibited an approximately 8- to 15-fold increase in migrating and invading cells, respectively (P < 0.005 for both). Immunofluorescence staining of OxR cells revealed translocation of E-cadherin and beta-catenin from their usual membrane-bound complex to the cytoplasm and nucleus, respectively. The OxR cells also had decreased expression of the epithelial adhesion molecules E-cadherin and plakoglobin and an increase in the mesenchymal marker vimentin. The KM12L4 OxR cells exhibited increased nuclear expression of Snail, an EMT-regulatory transcription factor, whereas the HT29 OxR cells exhibited an increase in nuclear expression of the EMT-associated transcription factor nuclear factor kappaB. CONCLUSION: We hypothesize that induction of EMT may contribute to the decreased efficacy of therapy in chemoresistant CRC, as the tumor cells switch from a proliferative to invasive phenotype. Further understanding of the mechanisms of chemoresistance in CRC will enable improvements in chemotherapy for metastatic disease.

Roles of nitric oxide synthase inhibition and vascular endothelial growth factor receptor-2 inhibition on vascular morphology and function in an in vivo model of pancreatic cancer.

PURPOSE: Both nitric oxide (NO) and vascular endothelial growth factor (VEGF) mediate tumor vascular function. Because these molecules regulate one another's expression, we hypothesized that NO synthase (NOS) inhibition produces effects comparable to those of anti-VEGF therapy on human pancreatic cancer xenografts. EXPERIMENTAL DESIGN: L3.6pl human pancreatic cancer cells were s.c. implanted in nude mice. On day 6, mice were randomized to receive (a) PBS (control), (b) DC101 [VEGF receptor 2 (VEGFR-2) antibody] by i.p. injection, (c) N-nitro-l-arginine (NNLA; NOS inhibitor) in the drinking water, or (d) both DC101 and NNLA. Mice were killed on day 20. RESULTS: DC101 and NNLA as single agents inhibited tumor growth by approximately 50% to 60% (P < 0.008 for both). Furthermore, combined therapy inhibited mean tumor growth by 89% (P < 0.008). Combined inhibition of VEGFR-2 and NOS also decreased mean vessel counts by 65% (P < 0.03) and vessel area by 80% versus controls (P < 0.001). In contrast to DC101 where vessel diameter was similar to control, NNLA decreased mean vessel diameter by 42% (P < 0.001). NNLA also led to a 54% (P < 0.03) decrease in tumor uptake of the perfusion marker Hoechst 33342 versus controls whereas DC101 decreased Hoechst 33342 staining by 43% (P < 0.03). The combination of inhibitors decreased perfusion by 73% (P < 0.03). CONCLUSIONS: Although VEGFR-2 can mediate NOS activity, the combination of VEGFR-2 and NOS inhibition significantly increased the antivascular effect over single agent therapy. The addition of NOS inhibition led to an even further alteration of tumor vessel morphology and vascular perfusion compared with VEGFR-2 blockade, suggesting that NO and VEGFR-2 have distinct but complementary effects on the tumor vasculature.

Vascular endothelial growth factor receptor-1 activation mediates epithelial to mesenchymal transition in human pancreatic carcinoma cells.

Our laboratory has shown that vascular endothelial growth factor receptor-1 (VEGFR-1) expression on human pancreatic cancer cell lines mediates cell migration and invasion. Because epithelial to mesenchymal transition (EMT) also plays a role in cell motility by altering the cell phenotype and morphology, we hypothesized that VEGFR-1 activation induces molecular alterations that mediate EMT. Our treatment of the human pancreatic cancer cell line L3.6pl with the VEGFR-1 ligands VEGF-A and VEGF-B led to morphologic changes characteristic of EMT, including loss of polarity, increased intercellular separation, and the presence of pseudopodia. Immunofluorescent staining with antibodies to E-cadherin and beta-catenin showed that VEGFR-1 activation led to translocation of E-cadherin and beta-catenin from their usual cell membrane-bound location to the cytoplasm and nucleus, respectively. Western blotting showed that VEGFR-1 activation led to decreased expression of the epithelial markers E-cadherin and plakoglobin, increased expression of the mesenchymal markers vimentin and N-cadherin, and increased nuclear expression of beta-catenin. Pretreatment of tumor cells with a VEGFR-1 blocking antibody inhibited the VEGFR-1-induced immunohistochemical and molecular changes in E-cadherin. VEGFR-1 activation led to an increase in expression of the EMT-associated transcription factors Snail, Twist, and Slug. The changes mediated by VEGFR-1 in this pancreatic carcinoma cell line are highly consistent with the changes characteristic of EMT. Given our previous finding of VEGFR-1-mediated tumor cell invasion and migration in pancreatic carcinoma cells, we hypothesize that VEGFR-1 plays a role in tumor progression in pancreatic cancer through the induction of EMT.

Targeting of urokinase plasminogen activator receptor in human pancreatic carcinoma cells inhibits c-Met- and insulin-like growth factor-I receptor-mediated migration and invasion and orthotopic tumor growth in mice.

Pancreatic carcinomas express high levels of urokinase-type plasminogen activator (uPA) and its receptor (uPAR), both of which mediate cell migration and invasion. We investigated the hypotheses that (a) insulin-like growth factor-I (IGF-I)- and hepatocyte growth factor (HGF)-mediated migration and invasion of human pancreatic carcinoma cells require uPA and uPAR function and (b) inhibition of uPAR inhibits tumor growth, retroperitoneal invasion, and hepatic metastasis of human pancreatic carcinomas in mice. Using transwell assays, we investigated the effect of IGF-I and HGF on L3.6pl migration and invasion. We measured the induction of uPA and uPAR following treatment of cells with IGF-I and HGF using immunoprecipitation and Western blot analysis. The importance of uPA and uPAR on L3.6pl cell migration and invasion was studied by inhibiting their activities with amiloride and antibodies before cytokine treatment. In an orthotopic mouse model of human pancreatic carcinoma, we evaluated the effect of anti-uPAR monoclonal antibodies with and without gemcitabine on primary tumor growth, retroperitoneal invasion, and hepatic metastasis. IGF-I and HGF mediated cell migration and invasion in L3.6pl cells. In addition, IGF-I and HGF induced uPA and uPAR expression in L3.6pl cells. In vitro, blockade of uPA and uPAR activity inhibited IGF-I- and HGF-mediated cell migration and invasion. Treatment of mice with anti-uPAR monoclonal antibody significantly decreased pancreatic tumor growth and hepatic metastasis and completely inhibited retroperitoneal invasion. Our study shows the importance of the uPA/uPAR system in pancreatic carcinoma cell migration and invasion. These findings suggest that uPAR is a potential target for therapy in patients with pancreatic cancer.

Vascular endothelial growth factor receptor-1 promotes migration and invasion in pancreatic carcinoma cell lines.

BACKGROUND: Vascular endothelial growth factor receptor-1 (VEGFR-1) is one of three receptor tyrosine kinases for VEGF, a key regulator of angiogenesis in cancer. Although VEGFRs initially were believed to be expressed exclusively on endothelial cells (ECs), recent studies have demonstrated the presence of VEGFR-1 on non-EC types. The authors hypothesized that VEGFR-1 is present and functional in pancreatic carcinoma cells, contributing to the malignant phenotype. METHODS: The authors assessed the expression of VEGFR-1 and its ligands in 11 pancreatic carcinoma cell lines by reverse-transcriptase-polymerase chain reaction, enzyme-linked immunosorbent assay, and/or Western blot analysis. The function of VEGFR-1 was evaluated by treating two representative cell lines with VEGF-B, a selective ligand for VEGFR-1, and/or a specific anti-VEGFR-1 antibody and assessing the effects on signaling, migration, invasion, and proliferation. RESULTS: All 11 pancreatic carcinoma cell lines expressed VEGFR-1 mRNA and protein, as well as the VEGFR-1 ligands VEGF-A and VEGF-B. Two representative cell lines (L3.6 and Panc-1) exhibited VEGF-B-induced mitogen-activated protein kinase signaling. A VEGFR-1 neutralizing antibody abrogated signaling, confirming that the ligand effect was mediated through VEGFR-1. VEGFR-1 stimulation by VEGF-A or VEGF-B was found to promote migration in both cell lines. Panc-1 cells also demonstrated enhanced Matrigel invasion after VEGFR-1 stimulation. VEGFR-1-dependent migration and invasion were blocked by the VEGFR-1 neutralizing antibody. VEGFR-1 activation did not appear to enhance cell proliferation. CONCLUSIONS: VEGFR-1 appears to be expressed ubiquitously in pancreatic carcinoma cell lines, in which it induces signaling and promotes migration and invasion. Overexpression of VEGF in tumors may activate tumor cells bearing VEGFR-1 via an autocrine pathway. Agents targeting VEGF or its receptors may have a dual inhibitory effect on tumor growth by suppressing both angiogenesis and tumor cell function.

RON, a tyrosine kinase receptor involved in tumor progression and metastasis.

Tyrosine kinase receptors mediate many critical cellular functions that contribute to tumor progression and metastasis and thus are potential targets for molecular-based cancer therapy. As has been found for many receptor tyrosine kinases, RON (recepteur d'origine nantais) and its ligand, macrophage-stimulating protein, have recently been implicated in the progression and metastasis of tumors. In in vitro experiments using colon and breast cancer cell lines, overexpression of RON led to increased invasion and migration of cancer cells and prevented apoptosis and anoikis. In addition, transgenic mice engineered to overexpress RON in the lung epithelium developed multiple pulmonary tumors, suggesting a role for RON in tumorigenesis. In human cancer specimens, increased RON expression has been demonstrated in colon, breast, ovarian, and lung tumors. Therefore, therapies designed to inhibit RON activation may hinder critical tumor survival mechanisms and play a role in the treatment of advanced disease.

Improving delivery of antineoplastic agents with anti-vascular endothelial growth factor therapy.

It is believed that impairments in delivery of antineoplastic agents to solid tumors result from abnormalities of the tumor microenvironment. Vascular endothelial growth factor (VEGF), the prototypical angiogenic molecule, is one of the main factors responsible for the development and maintenance of the aberrant tumor vascular network, which is characterized by chaotic, leaky blood vessels with high interstitial fluid pressure and inefficient blood flow. The authors proposed that anti-VEGF therapy would reduce the elevated interstitial fluid pressure in tumors, thereby improving blood flow and potentially improving delivery of cytotoxic agents to tumor cells. For the current report, the authors reviewed characteristics of the abnormal tumor vasculature created under the influence of VEGF, the resulting tumor microenvironment, how the tumor microenvironment may impede delivery of antineoplastic agents, and how the combination of anti-VEGF and cytotoxic therapy may maximize the efficacy of antineoplastic treatment regimens.

Expression and function of vascular endothelial growth factor receptor-1 on human colorectal cancer cells.

Vascular endothelial growth factor (VEGF) is associated with tumor angiogenesis and poor prognosis in human colorectal cancer (CRC). VEGF receptor-1 (VEGFR-1 or Flt-1) is a high-affinity receptor for VEGF and is typically considered specific to endothelial cells. Here we report the expression and function of VEGFR-1 in CRC cell lines. VEGFR-1 was expressed in all CRC cell lines studied as determined by RT-PCR, Western blot analysis, FACS, and ELISA. Treatment of the human CRC cell lines HT-29 and SW480 with VEGF-A (a ligand for both VEGFR-1 and -2) or VEGF-B (a ligand specific for VEGFR-1) led to activation of Erk-1/2, SAPK/JNK, and translocation of the p65 subunit of nuclear factor-kappaB into the nucleus. Both VEGF-A and -B led to significant induction of cell motility and invasiveness of CRC cells. Stimulation of cells with VEGF-A or -B also led to larger and more numerous colonies in soft agar. However, activation of VEGFR-1 did not increase CRC cell proliferation. In contrast to the previous paradigm that VEGFRs are not present on tumor cells of epithelial origin, we found that VEGFR-1 is present and functional on CRC cells, and activation by VEGF family ligands can activate processes involved in tumor progression and metastasis.