| Objective: To investgate the expression of histamine 2 receptor in the colorectal cancer,and the effect of histamine 2 receptor antagonist(H2RA, for example cimetidine,nizatidine) on the proliferation and apoptosis in human colorectal cancer cell line SW480.This study was designed to explore the machanism that H2RA(cimetidine,nizatidine) can effectively inhibit the proliferation and induce apoptosis in cell line SW480.Methods: Immunohistochemical staining was used to detect the expression of histamine 2 receptor in the colorectal cancer and human colorectal cancer cell line SW480. The growth inhibition effect of H2RA(cimetidine,nizatidine) against SW480 cells was measured by growth curve analysis,vitality detection and MTT assay. Cell morphology of SW480 cells was observed by optics microscope and inverted microscope.Phase distribution of cell cycle and cell apoptosis of H2RA(cimetidine,nizatidine) against SW480 cells was analyzed by flow cytometry(FCM).Results:1. The masculine expression of histamine 2 receptor on sixty human colorectal cancer is 86.667%,but this is 11.667% on sixty colorectal organization by the side of cancer,and 5% in human colorectal tissue. That means the expression of histamine 2 receptor on human colorectal cancer is confirmed highly,and the expression of histamine 2 receptor on human colorectal cancer is surpassed to the compared organization by the side of cancer or human colorectal tissue(P<0.01),and the difference is remarkable.The masculine expression of histamine 2 receptor on the moderately-low differentiated colorectal cancer is higher than the highly differentiated(P<0.05).2. The expression of histamine 2 receptor on human colorectal cancer cell line SW480 is located in cell membrane and (or) cell cytoplasm.The masculine signal is yellowish brown or yellow granulated.That means the expression of histamine 2 receptor on human colorectal cancer cell line SW480 is confirmed.3. The suppression rate of cimetidine(2.5μM,5μM,10μM,20μM,40μM) on the proliferation in human colorectal cancer cell line SW480 is 11.31%,24.87%,44.93%,64.19%,89.06%,and the suppression rate of nizatidine(1.25μM,2.5μM,5μM,10μM,20μM) is 14.51%,31.36%,47.12%,62.95%,87.89%.The growth inhibition effect of the H2RA(cimetidine,nizatidine) against SW480 cells after 24 hour was measured in evidence by MTT assay,and exhibited a dose-dependent modal.4. The cell colony twice-adding time of the control of SW480 cells is 34.42 hour.When the concentration of cimetidine adds from 0μM to 10μM,it's cell colony twice-adding time delays from 34.42 hour to 67.44 hour(P<0.01);when the concentration of nizatidine adds from 0μM to 5μM,it's cell colony twice-adding time delays from 34.42 hour to 61.34hour(P<0.01).That means cell colony twice-adding time is lengthened obviously when the H2RA(cimetidine,nizatidine) against SW480 cells after 24 hour,and the cell proliferation cycle is delayed,and the cell proliferation speed becomes slowly(P<0.01).5. As exposed to optics microscope and inverted microscope,compared to control,SW480 cells with Giemsa staining that treated with the H2RA(cimetidine,nizatidine) took on malignance declining as crimpled firstly,cellular bulk and heteromorphism dimimished,the amount of rounded cell manifolded,nucleolus bulk lessened,dyeing thin,the amount of nucleolus decreased,partial cell organs manifest side-gathering phenomenon on chromatin,and the link between SW480 cell is loosened , subsequently partial rounded cell is floated.When the H2RA(cimetidine 40μM,nizatidine 20μM) against SW480 cells after 3 day,SW480 cells change roundly,nucleolus smashed,shrinking nucleolus came into being,and part of those not adhibited cell wall. 6. Flow cytometry analysis reveals that the apoptosis of cimetidine against SW480 cells after 24 hour exhibited a dose-dependent modal.When the drug concentration of cimetidine is enhanced , compared to the control and the menstruum-Control,the cell content of G2-phase and S-phase declined whereas G1-phase increased obviously after exposure to cimetidine(P<0.01),which indicated that colon cancer cells arrested in G1-phase,and cells in G1-phase become perished slowly.The apoptosis of nizatidine against SW480 cells after 24 hour exhibited a dose-dependent modal.When the drug concentration of nizatidine is enhanced,the cell content of S-phase declined whereas G1-phase and G2-phase increased obviously after exposure to nizatidine(P<0.01),which indicated that colon cancer cells arrested in G1-phase and G2-phase,and cells in two phase become perished slowly.Conclusion:1. The expression of histamine 2 receptor on human colorectal cancer is confirmed , and the masculine expression of histamine 2 receptor on the moderately-low differentiated colorectal cancer is higher than the highly differentiated colorectal cancer.2. The expression of histamine 2 receptor on human colorectal cancer cell line SW480 is confirmed.3. The histamine 2 receptor antagonist (H2RA,for example cimetidine,nizatidine) can effectively inhibit the proliferation and induce apoptosis in human colorectal cancer cell line SW480. |
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