Establishment and characterization of a continuous murine uterine cervix cancer cell line metastatic to lymph nodes and lungs

The murine uterine cervix cancer (MUCC) cell line was derived from a chemically induced Kunming mouse uterine cervix cancer (U27) and maintained in culture on solid substrates for over 100 passages. Cultures were morphotypically heterogeneous and heteroploid, with a modal number of chromosomes = 80. Each cell showed at least two abnormal chromosomes. Immunogold-silver staining was positive for keratin, vimentin, and laminin but not for desmin. The population doubling time was 27.8 h with a saturation density of 3.2 X 10(5) cells/cm2 and a peak mitotic index of about 6%. MUCC cells produced colonies on tissue culture plastic (68%) and in soft agar (8%). MUCC cells were fully malignant inasmuch as they produced in syngeneic mice invasive tumors that reproducibly were metastatic to lymph nodes and lungs. The MUCC cell line is the first mouse cervix cancer cell line useful for the study of invasion and metastasis.

[3H]AF-DX 116 labels subsets of muscarinic cholinergic receptors in rat brain and heart

The in vitro binding properties of the novel muscarinic antagonist [3H]AF-DX 116 were studied using a rapid filtration technique. Association and dissociation rates of [3H]AF-DX 116 binding were rapid at 25 degrees C (2.74 and 2.70 X 10(7) min-1 M-1 for K+1; 0.87 and 0.93 min-1 for k-1) but 20-40 times slower at 0-4 degrees C (0.13 and 0.096 X 10(7) min-1 M-1 for k+1; 0.031 and 0.022 min-1 for k-1 in cerebral cortical and cardiac membranes, respectively). Kinetic dissociation constants (Kds) were estimated to be 31.8 nM and 30.9 nM at 25 degrees C; 23.1 nM and 0-4 degrees C for the cerebral cortex and heart, respectively. In saturation studies, [3H]AF-DX 116 labeled 29 percent of the total [3H](-)QNB binding sites in the cerebral cortical membranes and 87 percent in the cardiac membranes, with Kd values of 28.9 nM and 17.9 nM, respectively. Muscarinic antagonists inhibited [3H]AF-DX 116 binding in a rank order of potency of atropine greater than dexetimide greater than AF-DX 116 greater than PZ greater than levetimide in both tissues. Except for PZ/[3H]AF-DX 116 and AF-DX 116/[3H]AF-DX 116 in the cerebral cortex, all the antagonist competition curves had Hill coefficients close to one. Carbachol and oxotremorine produced shallow inhibition curves against [3H]AF-DX 116 binding in both tissues. Regional distribution studies with [3H](-)QNB, [3H]PZ and [3H]AF-DX 116 showed that most of the muscarinic receptors in the cerebral cortex, hippocampus, nucleus accumbens and corpus striatum are of the M1 subtype while those in the brainstem, cerebellum and other lower brain regions are of the M2 subtype. These results indicate that [3H]AF-DX 116 is a useful probe for the study of heterogeneity of muscarinic cholinergic receptors.

Thermodynamic analyses of pirenzepine binding to membrane-bound and solubilized muscarinic receptors from rat forebrain and heart

The thermodynamic properties of pirenzepine (PZ) binding to membrane-bound and digitonin-solubilized muscarinic receptors (mAChR) from the rat forebrain and heart were evaluated. Apparent dissociation constants (Kd) of PZ were measured from saturation studies using [3H]PZ for forebrain membrane-bound mAChR and from inhibition studies of (-)-[3H]quinuclidinyl benzilate binding using unlabeled PZ, at five different temperatures from 4 degrees C to 37 degrees C. The Kd values of PZ binding to both membrane-bound and solubilized mAChR decreased with decreasing temperature whereas the maximum receptor density was unchanged. The heterogeneity of membrane-bound mAChR characterized by PZ binding to mAChR from both tissues disappeared upon digitonin-solubilization of the mAChR. The magnitude of changes of the Kd values with temperature was greater in the solubilized mAChR, suggesting that some constituents in the membrane constrained the affinity changes. The Gibbs free energy of PZ binding to membrane-bound and solubilized mAChR were both negative. The Gibbs free energy for membrane-bound receptors decreased (more negative) whereas those for solubilized receptors increased (less negative) with increasing temperature. The change in entropy was the apparent major driving force for PZ binding to membrane-bound receptors with the change in enthalpy also being favorable. The change in enthalpy was the apparent major driving force for PZ binding to solubilized receptors at all temperatures with the change in entropy being unfavorable above 17 degrees C in the rat forebrain mAChR and above 10 degrees C in the heart mAChR. Our results suggest an important role for the biomembrane microenvironment and possible topographical differences in the binding sites which may contribute to the mechanism of muscarinic subtypes.

Solubilization with digitonin alters the kinetics of pirenzepine binding to muscarinic receptors from rat forebrain and heart

The binding properties of the putative M1 selective antagonist pirenzepine (PZ) to muscarinic acetylcholine receptor (mAChR) embedded in membranes and freed by solubilization with digitonin have been studied in the rat forebrain and heart. In the forebrain membranes, the k+1 and k-1 of [3H]PZ binding was 7.05 X 10(5) min-1 M-1 and 1.84 X 10(-3) min-1 (Kd = 3.34 nM), respectively, whereas those in heart membranes were estimated to be 1.21 X 10(5) min-1 M-1 and 7.46 X 10(-3) min-1 (Kd = 66 nM) by an indirect method. After solubilization, the kinetic parameters were determined as 3.17 X 10(5) min-1 M-1 and 2.23 X 10(-3) min-1 (Kd = 7.16 nM) in the forebrain and 2.41 X 10(5) min-1 M-1 and 1.41 X 10(-3) min-1 (Kd = 6.35 nM) in the heart. Similar dissociation constants were obtained from equilibrium saturation binding studies of [3H]PZ. Both high and low affinity binding sites for PZ were found in the forebrain membranes, whereas only one low affinity site was detected in the heart membranes. After solubilization, the inhibition curves in both tissues were better fitted to a one-site model with similar Ki values. The affinity of the agonist carbachol was decreased greatly in the heart and decreased slightly in the forebrain after solubilization to IC50 values that were similar in both tissues. Although 5'-guanylylimidodiphosphate was able to reduce the affinity of carbachol for membrane bound mAChR and to increase slightly the binding of (-)-[3H]quinuclidinyl benzilate it had no effect on ligand binding to the solubilized mAChR. The affinities of classic antagonists (-)-[3H]quinuclidinyl benzilate and atropine were not altered significantly by solubilization. Our results suggest that several different factors appear to be involved in the association and dissociation processes of PZ binding to the putative M1 (in forebrain) and M2 (in heart) mAChR in membranes. Most of these factors were separated from the receptors by solubilization under our conditions.

[Establishment of a mouse forestomach carcinoma cell line (MFC) with spontaneous hematogenous metastasis and preliminary study of its biological characteristics]

A mouse forestomach carcinoma cell line (MFC) prone to blood-born metastasis to lung was established in vitro. This cell line has been subcultured for more than 132 passages. MFC cells lacked in contact inhibition and, morphologically, appeared as round, polygonal and spindle cells. Ultrastructurally, there were abundant microvilli on the cellular surface and extensive filopodia in the cytoplasm; nuclei showed irregular shape with an increased nucleus-cytoplasm ratio; desmosomes, hemidesmosomes as well as a small number of tonofibrils were observed. The doubling time of MFC cell population was 24.7 hours. The average mitotic index was 32.9% and the maximum was 62% with 70-76 mode. The homotransplant efficiency was 100% (11/11). In morphology, the solid tumors induced were similar to FC tumor, from which the MFC cell line was derived and 81.8% (9/11) developed spontaneous lung metastasis. It is indicated that this cell line still retains the primary tumor's feature of spontaneous hematogenous metastasis. MFC cell line might be very useful in experimental treatment, study of tumor metastatic mechanism and isolating subpopulation.

[Establishment and biologic properties of a mouse uterine cervix cancer cell line (MUCC) with lymphatic and hematogenous metastatic capacities]

For study of tumor metastatic mechanism, a mouse uterine cervix cancer cell line (MUCC), as derived from a transplantable mouse uterine cervix cancer No. 27 (U 27) with metastatic capacities through lymphatics and blood, was established in vitro. It has been successfully maintained for more than 24 months through more than 100 passages. MUCC cells are epithelioid with definite malignant morphological features. The doubling time of the cell population is 27.8 hours. The average mitotic index is 30.6%, with a maximum of 58.9%. Chromosomes show aberration in number and structure. The homotransplant rate is 75% (9/12). The solid tumor, produced by homotransplant, is similar to the tumor U 27. Metastases are present in the lymph nodes and lungs in these 9 animal models. It is evident that this cell line retains the capacity of inducing daughter tumor lines with spontaneous lymphatic and blood metastases. MUCC cell line might be very useful in isolating subpopulations which possess the different metastatic abilities and the study of metastatic mechanism.

In vivo and in vitro studies on the regulation of cholinergic neurotransmission in striatum, hippocampus and cortex of aged rats

Young (3 months) and senescent (23 months) rats were challenged with oxotremorine both in vivo, to determine its effects on acetylcholine content in hemispheric regions, and in vitro, to assess its action on K+-evoked release of ACh from brain synaptosomes. The drug failed to inhibit KCl-induced [3H]ACh release from the P2 fraction of striatal and hippocampal homogenates of the senescent animals, whereas it was less efficient in increasing striatal ACh content. In contrast, oxotremorine was still able to stimulate an increase in ACh in the hippocampus and cerebral cortex of the aged rats to the same extent as it did in the young ones. The [3H]ACh output from striatal synaptosomes was lower in old rats with respect to young ones at low KCl depolarizing concentrations but was equal in the two groups at a high depolarizing concentration. In the hippocampus of the senescent rats, the release was significantly lower at each concentration of KCl used, resulting in a parallel downward-shift in the concentration-release plot. We also measured cholinergic muscarinic receptor binding in rat hemispheric regions using the radioligand [3H]dexetimide, a classical non-selective muscarinic receptor antagonist. It was found, in conformity with some of the literature, that receptor binding was decreased by about 32% in striatum of aged female rats as compared to younger rats. Changes were not observed in cortex and hippocampus. Analysis of the binding data indicated that the observed decrease in specific ligand binding was due to a decrease in the number of binding sites without a change in affinity. The results favor, once again, the cholinergic hypothesis for geriatric dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro and in vivo evidence for the existence of presynaptic muscarinic cholinergic receptors in the rat hippocampus

The intrahippocampal injection of kainic acid cleared 50% of muscarinic receptors and favored the detection of a further 20% loss in hippocampal presynaptic muscarinic receptors produced by electrolytic lesion of the medial septal nucleus as determined by Scatchard analysis of the saturation isotherms of [3H]dexetimide binding. In accordance, a decrease of about 20% in the in vivo accumulation of [3H]dexetimide in the hippocampus was found in animals lesioned in the medial septal nucleus. This effect occurred at both the dose of 5 micrograms/kg and at the saturating dose of 100 micrograms/kg of [3H]dexetimide. The results suggest that the loss was due to decreased receptor number rather than decreased receptor affinity.

Modifications in recognition sites for neurotransmitters in rat hippocampus by kainic acid lesion

The specific binding of the tritiated radioligands of dexetimide, serotonin, clonidine, prazosin, WB-4101 and dihydroalprenolol to hippocampal membranes was determined two weeks after producing a virtual complete degeneration of perikarya by the local application of 0.5 micrograms of kainic acid in the dorsal and ventral parts of the hippocampus. Afferent terminals were unaffected by the neurotoxin since the contents of noradrenaline, serotonin and acetylcholine, as well as the activity of choline acetyltransferase, were not modified. Scatchard analysis revealed that the kainic acid lesion produced a 60% decrease in the density of both cholinergic muscarinic binding sites and serotonin binding sites. A significant portion of alpha 1- and alpha 2-adrenoceptor binding sites are also associated with intrinsic neurons of the hippocampus, as shown by the approximately 30% reduction in the densities of tritiated WB-4101, prazosin and clonidine produced by the action of kainic acid. By contrast, the affinity and density of beta-adrenoceptor binding sites were unaffected by the lesion. It is suggested that the recognition sites of the different receptor populations surviving the lesion most likely reside on homologous and/or heterologous nerve terminals.