gastrins and Astrocytoma

It is well known that the amidated C-terminal part of gastrin is crucial for its interaction with the classical seven transmembrane domain receptors CCK-1 or CCK-2. Nevertheless, over the past 10 years, several groups have characterized new binding sites using peptides related to gastrin (particularly glycine-extended forms of gastrin) on various tumoral and nontumoral cell lines. In the present study, we focused on the human astrocytic tumoral cell line U373. Although it has been described that gastrin was able to inhibit the motility of these cells, we were unable to detect any classical CCK/gastrin receptor. On the other hand, by using the radiolabeled C-terminal heptapeptide of gastrin ((125)I-G-7), we evidenced a new binding site that possessed a pharmacological profile different from the classical CCK/gastrin receptors. This new gastrin binding site seemed to be coupled to G proteins and be implicated in c-Fos transcription gene. Moreover, we showed that G-7 was able to induce a strong inhibition of U373 cell migration, a crucial biological effect when we know that astrocytoma cells' migration in brain parenchyma constitutes a major feature of malignancy in astrocytic tumors.

Topics: Amino Acid Sequence; Astrocytoma; Binding Sites; Brain Neoplasms; Cell Division; Cell Movement; Cyclic AMP; Gastrins; Genes, fos; Humans; Inositol Phosphates; Iodine Radioisotopes; Isotope Labeling; Kinetics; Luciferases; Molecular Sequence Data; Oligopeptides; Receptor, Cholecystokinin A; Receptor, Cholecystokinin B; Receptors, Cholecystokinin; Reverse Transcriptase Polymerase Chain Reaction; Second Messenger Systems; Transfection; Tumor Cells, Cultured

Human astrocytic tumors grow into the normal brain parenchyma either as localized tumors, or as highly diffuse neoplasms. The diffuse phenotype relates to a specific sub-type of neoplastic astrocytes with a high motility and invasion capacity. Motility features refer to locomotion while invasion features refer to protease secretion. Our data reveal that several peptides belonging to the gastrin/cholecystokinin peptide class are able to significantly (and in certain cases very significantly) modify the level of tumor growth (at the level of cell proliferation and/or cell death), of motility and of invasion in various experimental models of human astrocytic tumors. We are synthesizing various gastrin/cholecystokinin-related peptides in order to develop clinical applications with which we want to inhibit astrocytic tumor growth, individual neoplastic astrocytic motility and the invasion of the normal brain parenchyma.

Topics: Animals; Astrocytoma; Biomarkers, Tumor; Brain Neoplasms; Disease Models, Animal; Drug Evaluation, Preclinical; Gastrins; Humans; Mice; Sincalide

The hormone sensitivity of a tumor is traditionally based on the presence of steroid receptors. Other factors should be taken into consideration. Here, we studied the influence of 10 nM epidermal growth factor (EGF) or gastrin on the proliferation of human ex vivo tumor cultures by means of [3H]thymidine autoradiography. The immunohistochemical EGF-receptor expression was also quantified by means of computer-assisted microscopy. The results demonstrated that the proliferation of 6/11 astrocytic tumors and 3/16 meningiomas was sensitive to at least one factor tested, i.e. EGF or gastrin (P < 0.01), and 5 of these 9 'hormone-sensitive' tumors were sensitive to both factors. The immunohistochemical labeling index for the EGF receptor was higher than 80% in 15/16 meningiomas, but only in 6/11 gliomas (P < 0.01). These results suggest that EGF and gastrin are important for astrocytic tumor proliferation and significantly (P < 0.01) less important for meningiomas. Thus, astrocytic tumors may be steroid insensitive in term of cell growth, but are certainly not hormone insensitive.

Topics: Astrocytoma; Cell Division; Epidermal Growth Factor; ErbB Receptors; Gastrins; Humans; Immunohistochemistry; Meningioma; Tumor Cells, Cultured

Gastrin and cholecystokinin (CCK) mediate their effects through at least two types of receptors (CCK receptors A and B). While it has been hypothesized that gastrin, a stimulator of gastric acid secretion, is also a neurotransmitter and a stimulator of cell proliferation in various normal and neoplastic tissues, its effect on astrocytic brain tumors has not been actively investigated.. Our goal was to determine the effects of gastrin and gastin and/or CCK antagonists on the proliferation in vitro of astrocytic tumor cells by use of both established cell lines and primary cell cultures of tumor tissue.. Ten established astrocytic tumor cell lines, SW1088, SW1783, Hs683, H4, U87, U118, U138, U373, T98G, and A172, were studied. The effects of added gastrin (at 0.01, 0.1, and microM) and the gastrin/CCK antagonists L-365,260, CI-988, L-364,718, and JMV 234 (each at 0.01, 0.1, and 1 microM) on the cellular proliferation rates of the 10 cell lines were indirectly measured by use of the colorimetric tetrazolium assay. The influence of gastrin (at 0.01 microM) on the cellular proliferation of primary cultures from nine freshly explanted astrocytic tumors was assessed by means of tritiated thymidine uptake and autoradiography.. At specific concentrations, added gastrin increased the cellular proliferation of three established astrocytic cell lines (A172, Hs683, and SW1088), decreased it in two (U373 and T98G), and was without effect on the remaining five. Gastrin decreased cellular proliferation in one primary astrocytic tumor cell culture, stimulated it in five, and had no apparent effect in the remaining three. L-365,260, a CCK receptor B antagonist used at 0.01 microM, increased cellular proliferation in seven cell lines (A172, H4, Hs683, SW1783, T98G, U118, and U138), decreased it in one (U87), and had no effect in the remaining two. CI-988, another CCK receptor B antagonist used at 0.01 microM, inhibited cellular proliferation in five cell lines (A172, H4, SW1783, U373, and U87), stimulated it in two (T98G and U138), and had no effect in three. The CCK receptor A antagonists L-364,718 and JMV 234, both used at 0.01 microM, affected the cellular proliferation of only three of the 10 cell lines.. These results suggest that gastrin (and perhaps CCK that belongs to the same peptide family) may play a role in the growth of a substantial proportion of human astrocytic tumors.

Topics: Amino Acid Sequence; Astrocytoma; Autoradiography; Benzodiazepinones; Brain Neoplasms; Cell Division; Cholecystokinin; Devazepide; Gastrins; Hormone Antagonists; Humans; Indoles; Meglumine; Molecular Sequence Data; Peptide Fragments; Phenylurea Compounds; Receptors, Cholecystokinin; Sincalide; Thymidine; Tritium; Tumor Cells, Cultured

We have investigated the potential role of gastrin in the regulation of cell growth in human astrocytic tumors. To this end we have used synthetic analogs of gastrin and cholecystokinin (CCK) which behave as gastrin and/or CCK antagonists, e.g. compounds JMV-97, JMV-209 and JMV-179. Their effects on astrocytic tumor cell proliferation was investigated by the use of the colorimetric MTT assay. The in vitro biological models used in the present study included the SW1088, U87 and U373 astrocytic tumor cell lines. The results demonstrated marked influence of gastrin and CCK antagonists in the regulation of astrocytic tumor growth. This suggests that gastrin and/or CCK antagonists might be tested in experimental glioblastoma.

Topics: Astrocytes; Astrocytoma; Brain Neoplasms; Cholecystokinin; Gastrins; Glioblastoma; Humans; Peptide Fragments; Sincalide; Tumor Cells, Cultured