cholecystokinin and Glioma

Cholecystokinin (CCK) is a gut-brain peptide has been described to be able to induce mitosis according to recent studies. Additionally, conflicting data has been published on whether tumours of the central and peripheral nervous system in general, and gliomas in particular, express CCK receptors. In the present in vitro study we employed reverse transcription followed by the polymerase chain reaction (RT-PCR) to investigate whether mRNA for CCK-A and CCK-B receptors as well as CCK peptide itself is present in primary human gliomas and the U-87 MG GBM cell line. The data show that 14/14 (100%) of the primary gliomas exhibited mRNA expression for the CCK peptide gene and the B receptor including the U-87 MG cells, whereas, only 2/14 (14%) showed presence of the CCK-A receptor. The presence of CCK receptors together with CCK peptide expression itself suggests presence of an autocrine loop controlling glioma cell growth. In support of this conclusion, a neutralizing antibody against the CCK peptide exhibited a dose dependent inhibition of cell growth whereas, antagonists to CCK caused a dose depend inhibition of exogenous stimulated glioma cell growth in vitro, via the CCK-B receptor which is PKC activated. Assessment of apoptosis and proteasome activity were undertaken and we report that treatment with CCK antagonists decreased proteasome and increased caspase-3 activity. These data indicate that CCK peptide and CCK-B are abundant in human gliomas and they act to stimulate cell growth in an autocrine manner, primarily via the high affinity CCK-B receptor, which was blocked by antagonists to CCK, perhaps via apoptosis.

Topics: Autocrine Communication; Brain Neoplasms; Caspase 3; Caspase Inhibitors; Cell Line, Tumor; Cell Proliferation; Cholecystokinin; Cyclic AMP; Dose-Response Relationship, Drug; Glioma; Humans; Hydrolysis; Paracrine Communication; Phosphatidylinositols; Proteasome Endopeptidase Complex; Receptors, Cholecystokinin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Thymidine

The effect of the cholecystokininB (CCKB) receptor-selective cholecystokinin octapeptide (CCK-8) analog SNF 9007 on forskolin-stimulated adenylyl cyclase activity in NG108-15 hybrid cells was measured. The activity of SNF 9007 was compared to the delta opioid agonists D-Pen2-D-Pen5-enkephalin (DPDPE, delta 1 receptor-selective) and Tyr-D-Ala-Phe-Glu-Val-Val-Gly-NH2, (D-Ala2-deltorphin II, delta 2-receptor-selective) because SNF 9007 binds with moderate affinity to delta opioid receptors. SNF 9007 inhibited forskolin-stimulated adenylyl cyclase activity with efficacy similar to DPDPE. IC50 determinations showed that D-Ala2-deltorphin II was the most potent, followed by DPDPE, then SNF 9007 (IC50 values = 0.013, 0.21 and 4.8 microM, respectively). CCK-8 had no effect on adenylyl cyclase activity. The delta 1 receptor-selective antagonist 7-benzylidenenaltrexone hydrochloride (BNTX, 10 nM) had no effect on the activity of any of these agonists, but the delta 2 receptor-selective antagonist naltriben methanesulfonate (NTB, 10 nM) increased IC50 values of all the agonists. Combinations of BNTX and NTB (10 nM each) increased the D-Ala2-deltorphin II IC50 value 12-fold, the DPDPE IC50 value 18-fold and the SNF 9007 IC50 value 26-fold. The effect of the combined delta antagonists on SNF 9007 activity was different from the effect on DPDPE or D-Ala2-deltorphin II activity. These data suggest that the interaction of the CCK-8 analog SNF 9007 with opioid receptors in NG108-15 hybrid cells is different from the interaction of opioid peptides with these receptors.

Topics: Adenylyl Cyclase Inhibitors; Amino Acid Sequence; Analgesics; Cholecystokinin; Enkephalin, D-Penicillamine (2,5)-; Enkephalins; Enzyme Inhibitors; Glioma; Hybrid Cells; Molecular Sequence Data; Neuroblastoma; Oligopeptides; Pain; Peptide Fragments; Receptors, Opioid, delta

Cholecystokinin (CCK) is known to stimulate cell proliferation but involvement of CCKB type receptors has not been exactly demonstrated so far. We examined the effect of CCK-8S and two receptor agonists on rat glioma C6 cells when using different CCKB receptor agonists and antagonists. Both CCK-8S and CCKB receptor agonists BC 264 and Suc-Trp-N(Me)Nle-Asp-Phe-NH2 stimulate [3H]thymidine incorporation. These effects were inhibited by CCKB receptor antagonist L-365,260 over 100-fold more effectively than it was seen by using CCKA receptor antagonist L-364,718. The data indicate that CCKB receptor agonists are potent stimulants of rat glioma C6 cell DNA synthesis suggesting that CCKB receptor activation is involved in cell proliferation within the central nervous system.

Topics: Amino Acid Sequence; Animals; Benzodiazepinones; Cell Division; Cholecystokinin; Devazepide; DNA; Glioma; Hormone Antagonists; Molecular Sequence Data; Oligopeptides; Peptide Fragments; Phenylurea Compounds; Rats; Receptors, Cholecystokinin; Sincalide; Thymidine; Tritium; Tumor Cells, Cultured

The present study was undertaken to compare binding characteristics of CCKB-type receptors in guinea-pig cortex, Jurkat T-cells, GH3 cells and C6 cells. The rank order of potency of a variety of CCK agonists and antagonists in inhibiting specific [3H]CCK-8S binding was highly correlated for the 4 CCKB receptor models as demonstrated by a computer-assisted statistical analysis. Taking the ligand binding profiles as the criterion it is concluded that CCKB receptors in guinea-pig cortex, Jurkat T-cells, pituitary GH3 cells and rat glioma C6 cells share identical pharmacological properties.

Topics: Animals; Binding, Competitive; Cell Line; Cerebral Cortex; Cholecystokinin; Glioma; Guinea Pigs; Kinetics; Pituitary Gland, Anterior; Rats; Receptors, Cholecystokinin; Sincalide; Structure-Activity Relationship; Tritium; Tumor Cells, Cultured