ABSTRACT
Cancers of the esophagus and stomach constitute a major cause of cancer deaths worldwide. Despite improvements in both surgical techniques and (radio) chemotherapy regimens, these tumors remain a great therapeutic challenge. Thus, there is a need for innovative medical treatment strategies effective even in advanced disease. An emerging understanding of the molecular events that characterize carcinogenesis, tumor growth and spread may provide novel targets in cancer therapy. In this review we discuss novel strategies to inhibit growth, angiogenesis, invasion, and spread of tumors and to induce apoptosis. Therapeutic strategies discussed include agents targeting the epidermal growth factor receptor (EGFR) family, the mitogen-activated protein kinase (MAPK) pathway, regulators of apoptosis (NF-kappaB, bcl-2, and the peripheral benzodiazepine receptor), cyclooxygenase-2, the vascular-endothelial growth factor receptor and matrix metalloproteinases.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Biomarkers, Tumor/genetics , Esophageal Neoplasms/genetics , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Apoptosis/drug effects , Apoptosis/genetics , Cell Transformation, Neoplastic/drug effects , Cell Transformation, Neoplastic/genetics , Cell Transformation, Neoplastic/pathology , Esophageal Neoplasms/blood supply , Esophageal Neoplasms/drug therapy , Esophageal Neoplasms/pathology , Gene Expression Regulation, Neoplastic/drug effects , Humans , Neovascularization, Pathologic/drug therapy , Neovascularization, Pathologic/genetics , Neovascularization, Pathologic/pathology , Prognosis , Signal Transduction/drug effects , Signal Transduction/geneticsABSTRACT
Therapeutic options to inhibit the growth and spread of neuroendocrine (NE) gastrointestinal tumours are still limited. Since gefitinib (4-(3-chloro-4-fluoroanilino)-7-methoxy-6-(3-morpholinopropoxy)quinazoline), an inhibitor of epidermal growth factor receptor-sensitive tyrosine kinase (EGFR-TK), had been shown to suppress potently the growth of various non-NE tumour entities, we studied the antineoplastic potency of gefitinib in NE gastrointestinal tumour cells. In human insulinoma (CM) cells, in human pancreatic carcinoid (BON) cells and in NE tumour cells of the gut (STC-1), gefitinib induced a time- and dose-dependent growth inhibition by almost 100%. The antiproliferative potency of gefitinib correlated with the proliferation rate of the tumour cells. So the IC(50) value of gefitinib was 4.7+/-0.6 microM in the fast-growing CM cells, still 16.8+/-0.4 microM in the moderate-growing BON cells, and up to 31.5+/-2.5 microM in the slow-growing STC-1 cells. Similarly, the induction of apoptosis and cell-cycle arrest by gefitinib differed according to growth characteristics: fast-growing CM cells displayed a strong G0/G1 arrest in response to gefitinib, while no significant cell-cycle alterations were seen in the slow-growing STC-1. Vice versa, the proapoptotic effects of gefitinib, as determined by caspase-3 activation and DNA fragmentation, were most pronounced in the slow-growing STC-1 cells. Using cDNA microarrays, we found extensive changes in the expression of genes involved in the regulation of apoptosis and cell cycle after incubation with gefitinib. Among them, an upregulation of the growth arrest and DNA damage-inducible gene GADD153 was observed. Phosphorylation of ERK1/2, which inhibits GADD153 expression, was reduced in a time-dependent manner. However, no gefitinib-induced activation of the GADD153-inducing p38 mitogen-activated protein kinase was detected. Our data demonstrate that the inhibition of EGFR-TK by gefitinib induces growth inhibition, apoptosis and cell-cycle arrest in NE gastrointestinal tumour cells. Thus, EGFR-TK inhibition appears to be a promising novel approach for the treatment of NE tumour disease.
Subject(s)
Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Carcinoma, Neuroendocrine/drug therapy , ErbB Receptors/drug effects , Gastrointestinal Neoplasms/drug therapy , Quinazolines/pharmacology , Blotting, Western , Carcinoid Tumor/drug therapy , Carcinoid Tumor/genetics , Carcinoma, Neuroendocrine/genetics , Cell Cycle/drug effects , Cell Line, Tumor , Dose-Response Relationship, Drug , Fluorescent Antibody Technique , Gastrointestinal Neoplasms/genetics , Gefitinib , Gene Expression Regulation, Neoplastic/drug effects , Humans , Insulinoma/drug therapy , Insulinoma/genetics , Oligonucleotide Array Sequence Analysis , Pancreatic Neoplasms/drug therapy , Pancreatic Neoplasms/genetics , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
The use of restricted replication-competent adenoviruses (RRCAs) inducing tumor cell-specific lysis is a promising approach in cancer gene therapy. However, the use of RRCAs in humans carries considerable risk, since after injection into the patient, further regulation or inhibition of virus replication from the outside is impossible. Therefore, we have developed a novel system allowing external pharmacological control of RRCA replication. We show here that a tumor-selective E1B-deleted RRCA can be tightly regulated by use of doxycycline (dox)-controlled adenoviral E1A gene expression, which in turn determines vector replication. RRCA replication is switched on by addition and switched off by withdrawal of dox. The system results in efficient tumor cell killing after induction by dox, whereas cells are unaffected by the uninduced system. It was also employed for efficient external control of transgene expression from cotransfected replication-deficient adenovectors. Furthermore, the use of a liver cell-specific human alpha1-antitrypsin (hAAT)-promoter driving a tetracycline-controlled transcriptional silencer allowed specific protection of cells with hAAT-promoter activity in the absence of dox in vitro and in vivo, delineating a new principle of 'tissue protective' gene therapy. The concept of external control of RRCAs may help to improve the safety of cancer gene therapy.
Subject(s)
Adenoviridae/genetics , Doxycycline/pharmacology , Genetic Therapy/methods , Neoplasms/therapy , Protein Synthesis Inhibitors/pharmacology , Virus Replication/genetics , Adenovirus E1A Proteins/metabolism , Adenovirus E1B Proteins/genetics , Animals , Gene Deletion , Humans , Mice , Mice, Nude , Tumor Cells, Cultured , Virus Replication/drug effectsABSTRACT
Specific ligands of the peripheral benzodiazepine receptor (PBR) are known to induce apoptosis and cell cycle arrest in oesophageal cancer cells. However, the underlying mechanisms are still unknown. Here, we investigated the transcriptional alterations and activation of protein kinases in response to PBR-specific ligands. Using cDNA arrays, we examined the transcriptional effects of the PBR-specific ligand FGIN-1-27 in two oesophageal cancer cell lines, KYSE-140 (squamous cell carcinoma) and OE-33 (adenocarcinoma). In oesophageal cancer cells, FGIN-1-27 induced extensive changes in the expression of genes involved in the regulation of apoptosis and cell cycle. Both in oesophageal cancer cell lines (KYSE-140, OE-33) we observed a strong upregulation of the growth arrest and DNA-damage-inducible genes, gadd45 and gadd153, in response to PBR ligands. gadd genes are known to be induced by p38MAPK activation. Using Western blotting we detected a time- and dose-dependent phosphorylation of p38MAPK, which was found to be functionally involved in gadd induction, apoptosis, and cell cycle arrest. In conclusion, our data indicate that PBR-specific ligands cause apoptosis and cell cycle arrest by activation of the p38MAPK pathway and induction of gadd45 and gadd153.
Subject(s)
Apoptosis , Carcinoma, Squamous Cell/genetics , Carcinoma, Squamous Cell/pathology , Cell Cycle , Esophageal Neoplasms/genetics , Esophageal Neoplasms/pathology , Gene Expression Regulation, Neoplastic , Mitogen-Activated Protein Kinases/pharmacology , Proteins , Receptors, GABA-A/metabolism , Blotting, Western , CCAAT-Enhancer-Binding Proteins/biosynthesis , DNA Damage , Humans , Indoleacetic Acids/pharmacology , Intracellular Signaling Peptides and Proteins , Ligands , Oligonucleotide Array Sequence Analysis , Phosphorylation , Protein Biosynthesis , Reverse Transcriptase Polymerase Chain Reaction , Signal Transduction , Transcription Factor CHOP , Transcription Factors/biosynthesis , Tumor Cells, Cultured , p38 Mitogen-Activated Protein Kinases , GADD45 ProteinsABSTRACT
BACKGROUND AND AIMS: Photodynamic therapy (PDT) is a new treatment modality for early esophageal neoplasia. With two absorption maxima in the visible light range (550 and 588 nm) hypericin is a very promising photosensitizer for PDT with incoherent light sources. We studied the effects of photosensitizing hypericin in both primary cell cultures and cell lines (squamous: Kyse-140 and adenocarcinoma: OE-33) of human esophageal cancer using an incoherent white light source. MATERIALS AND METHODS: Esophageal cancer cells were preincubated (4-24 h) with hypericin (10 nM-1 micro M) and then irradiated with a light energy dose of 30 J/cm(2). RESULTS: Hypericin showed strong phototoxic effects and induced apoptosis in a dose-dependent fashion. The IC(50) value of hypericin phototoxicity was approximately 30 nM in both squamous and adenocarcinoma cells. In the concentrations used nonphotoactivated hypericin showed no toxic or apoptotic potency. The phototoxicity of hypericin was compared to that of delta-aminolevulinic acid (5-ALA), which is already being used for photodynamic therapy of gastrointestinal cancer. 5-ALA produced similar phototoxic effects but at a much higher dose (IC(50) 182+/-8 micro M in Kyse-140 and 308+/-40 micro M in OE-33 cells). Moreover, 5-ALA did not induce apoptosis to a relevant extent. CONCLUSION: Hypericin is a very promising new photosensitizer for innovative photodynamic therapy of esophageal cancer. Both the well known clinical safety of hypericin and the lower costs of broad band light sources argue in favor of clinical trials.
Subject(s)
Adenocarcinoma/drug therapy , Antineoplastic Agents/therapeutic use , Carcinoma, Squamous Cell/drug therapy , Esophageal Neoplasms/drug therapy , Perylene/analogs & derivatives , Perylene/pharmacology , Photochemotherapy/methods , Photosensitizing Agents/therapeutic use , Aminolevulinic Acid/therapeutic use , Anthracenes , Apoptosis/drug effects , Dose-Response Relationship, Radiation , Female , Humans , Male , Middle Aged , Time Factors , Tumor Cells, Cultured/drug effectsABSTRACT
Extracellular ATP is known to inhibit growth of various tumours by activating specific purinergic receptors (P2-receptors). Since the therapy of advanced oesophageal cancer is unsatisfying, new therapeutic approaches are mandatory. Here, we investigated the functional expression and potential antiproliferative effects of P2-purinergic receptors in human oesophageal cancer cells. Prolonged incubation of primary cell cultures of human oesophageal cancers as well as of the squamous oesophageal cancer cell line Kyse-140 with ATP or its stable analogue ATP gamma S dose-dependently inhibited cell proliferation. This was due to both an induction of apoptosis and cell cycle arrest. The expression of P2-receptors was examined by RT-PCR, immunocytochemistry, and [Ca(2+)](i)-imaging. Application of various extracellular nucleotides dose-dependently increased [Ca(2+)](i). The rank order of potency was ATP=UTP>ATP gamma S>ADP=UDP. 2-methylthio-ATP and alpha,beta-methylene-ATP had no effects on [Ca(2+)](i). Complete cross-desensitization between ATP and UTP was observed. Moreover, the phospholipase C inhibitor U73122 dose-dependently reduced the ATP triggered [Ca(2+)](i) signal. The pharmacological features strongly suggest the functional expression of G-protein coupled P2Y(2)-receptors in oesophageal squamous cancer cells. P2Y(2)-receptors are involved in the antiproliferative actions of extracellular nucleotides. Thus, P2Y(2)-receptors are promising target proteins for innovative approaches in oesophageal cancer therapy.