ABSTRACT
The experiment was carried out on cultured human stomach glandular carcinoma (SGC-7901 cell line). We previously reported the cytochemical changes of (Na~+-K~+)-ATPase activity and the changes of microvilli. We here studied the relationship among the cAMP, cAMP-PDEase, Mg~(++)-ATPase activity, the cell growth and differentiation. Cells were exposed to Immol/L cAMP together with 1 mmol/L theophylline. We showed cAMP specific fluorescence by immunocytochemical method, Mg~(++)-ATPase and cAMP-PDEase activity by cytochemical methods. We found that cAMP with theophylline not only inhibited the growth of these SGC-7901 cells as shown by our previous result, but also decreased the activity of Mg~(++)-ATPase and 3', 5'-cyclic monophosphate phosphodiesterase. The result indicates that exogenous cAMP can inhibit 3', 5'-cAMP-PDEase and Mg~(++)-ATPase activity and increase cAMP level in cell, and cAMP regulated the growth and differentiation of SGC-7901 cell line
ABSTRACT
This study was carried out to investigate the effects of ATP on cultured human stomach carcinoma MGC-803 cells. After ATP(0.16—0.23 mg/ml, 24—120 hrs)treatment, inhibition of cell growth rate was observed. The inhibition rate reached 80% after 96 hr exposure to ATP. At the same time, anti-tubulin immunofluorescent staining showed increase of organized microtubules (MT) in ATP-treated MGC-803 cells, in contrast with the poor MT immunofluorescence in control MGC-803 cells. By using rhodamie phalloidin combined staining, increased number of actin bundles, took the place of actin dots and patches which were seen in control MGC-803 cells. Immunofluorescent staining of fibronectin in ATP-treated MGC-803 cells was also increased evidently as compared with the control MGC-803 cells. Concomitant with the improvement of MT and stress fiber organization, the cell Concohas become more flattened. It appeared that the increase of MT and stress fibers was closely related to the recovery of cell morphology in ATP treated tumor cells. It is therefore concluded that ATP not only may inhibit tumor cell proliferation, but also may induce differentiation of cell morphology of tumor cells through its action on cytoskeletal structures.
ABSTRACT
The experiment was carried out on Hepatoma-22 ascitic tumor cells of mice in vivo. Daily injection of 2 mg cAMP with 1 mg theophylline into the peritoneal cavity for 7 and 8 days, then these animals were sacrificed. We found that cAMP with theophylline inhibit the growth of tumor cells of Hepatoma-22 ascitic and decrease the activity of Mg~(++), (Na~+-K~+)-ATPase and cAMP-PDE on the cell surface of H-22 tumor cells of mice by cytochemical electron microscopy. Exogenic cAMP and theophlline decrease the activities of these enzymes and elevate the intracellular content of cAMP. These may indicate the reversion transformation of the cancer cell.
ABSTRACT
The experiments was conducted on the fibroblasts of human prepuce in vitro todemonstrate the distribution of cytoplasmic microfilaments with Coomassie Blue R250.It has been found that the distribution of the cytoplasmic microfilaments canbe disturbed by the specific inhibitor,Cytochalasin B.We also observed the inhi-bition by Cytochalasin B was reversible.The cytoplasmic microfilaments regainedtheir normal distribution after the Cytochalasin B was removed.This result further confirmed that the staining method of Coomassie BrilliantBlue R 250 is reliable to demonstrate microfilaments in cultured fibrablasts.
ABSTRACT
cells was not influenced if they were treated with 1(T~(-5)M taxol and 0.1?g/ml colcemid for 2 hrs. either simultaneously or in accession. The secretory activity of these cells was evidently inhibited after treatment with 4?g/ml cytochalasin B for 6 hrs. Our results indicate that the mucus secretion of MGc80-3 human stomach cancer cells closely depended on the presence of both microtubules and microfilaments. We also found that the mucus secretion of MGc80-3 cells was enhanced by treatment with l?g/ml pilocarpine for 6 hrs. The proliferation of MGc80-3 cell population was inhibited by thiazolidine-4 carboxylic acid. However, the secretory activity of these cells was evidently enhanced after treatment with 0.1?g/ml thiazolidine-4 carboxylic acid for 10 hrs. The stimulating effect of pilocarpine and thiazolidine-4 carboxylic acid disappeared after the microtubules and microfilaments were disassembled by treatment with colcemid and cytochalasin B. In addition, our experiments also show that the mucus secretion of these cells was increased after treatment with ImM db-cAMP. These findings convincingly support the assumption that motile events placed under the control of the microtubular-microfilamentous system are intimately involved in the mucus secretion of MGc80-3 human stomach cancer cells. cells was not influenced if they were treated with 1(T~(-5)M taxol and 0.1?g/ml colcemid for 2 hrs. either simultaneously or in accession. The secretory activity of these cells was evidently inhibited after treatment with 4?g/ml cytochalasin B for 6 hrs. Our results indicate that the mucus secretion of MGc80-3 human stomach cancer cells closely depended on the presence of both microtubules and microfilaments. We also found that the mucus secretion of MGc80-3 cells was enhanced by treatment with l?g/ml pilocarpine for 6 hrs. The proliferation of MGc80-3 cell population was inhibited by thiazolidine-4 carboxylic acid. However, the secretory activity of these cells was evidently enhanced after treatment with 0.1?g/ml thiazolidine-4 carboxylic acid for 10 hrs. The stimulating effect of pilocarpine and thiazolidine-4 carboxylic acid disappeared after the microtubules and microfilaments were disassembled by treatment with colcemid and cytochalasin B. In addition, our experiments also show that the mucus secretion of these cells was increased after treatment with ImM db-cAMP. These findings convincingly support the assumption that motile events placed under the control of the microtubular-microfilamentous system are intimately involved in the mucus secretion of MGc80-3 human stomach cancer cells.
ABSTRACT
This experiment was carried out in young adult albino mice,which were injectedwith Ehrlich ascites tumor cells intraperitoneally to produce Ehrlich ascites tumor.The animals were divided into 2 groups.The first group received cAMP plusaminophylline for 5 to 13 days after inoculation.The second group received saline ascontrol.We found that in the administration of cAMP together with aminophylline,thegrowth of Ehrlich ascites tumor cells was inhibited to the extent of 53% at the 9thdays after inoculation.Early or later than the 9th day,the inhibitory rates were marklylower.By using cAMP immunocytochemical method,it was found that on the9th day of inoculation,there was an increase of the intensity of intracellualr cAMPspecific fluorescence in tumor cells of the cAMP treated mice in comparison withthose of the control.It also inhibited the 3',5'-cAMP-PDE activity on the 5th to 7thday after inoculation.Under the dark field microscope on the surface of the Ehrlich tumor cells therewere numerous“brush-like”microvilli,but they were not visible on the surfaceafter treated with cAMP together with aminophylline.The agglutination by theCon.A,was decreased markly on the 7th to 9th day after the inoculation.The possible relationship between the level of intracellular cAMP and of the3',5'-cAMP-PDE,and especially the inhibition of the formation of microvilli onthe treated tumor cell surface is discussed in this paper.