| In recently years,there have been many researches on phycoerythrin restraining tumor activity,which were mainly conducted in the following two ways.One is that the phycoerythrin is a new type of photosensitizer that can mediate Photodymamic Therapy.Another one is the ability of directly restraining tumor inside and outside the body.Inside the body,the crude phycoerythrin extracts have a restrain effect on the growth of S180 sarcoma and liver cancer H22 tumor;while outside the body,phycoerythrin can obviously suppress colon cancer SW-480 cells and induce cell apoptosis;it also has restrain effect on cervical carcinoma cell Hela proliferation and induces cell apoptosis through periodically blocking cells.Currently,there are researches indicating that phycoerythrin can restrain proliferation of human gastric carcinoma SGC-7901 cells,but action mechanism is not clear.So,this experiment shall take this as the breakthrough point to carry on the basic study of phycoerythrin anti-tumor experiment,and explore tumor inhibition mechanism of human gastric carcinoma SGC-7901 cells.This experiment adopts MTT methods to inspect the growth inhibition of phycoerythrin to the SGC-7901 cells,and the results showed that phycoerythrin has a strong restrain ability to SGC-7901 cells proliferation.Through calculating,the IC50 is 2.55μM after phycoerythrin acting on SGC-7901 cells for 72h.Applying the inverted microscope to observe the morphology of SGC-7901 cells after phycoerythrin acting on it for 48h,the results showed that with the growth of drug concentration,the morphology of SGC-7901 cells changes distinctly and most of the negative control cells are plump,adherent to cell war,and sharp edge;it can be observed that the SGC-7901 cells of each drug administration group are shrinkage and turning round,and with the increase of dosage,the attached cells reduce and the suspended cells increase.Using fluorescence microscope to observe the morphology of SGC-7901 cells after phycoerythrin acting on it for 48h,we can found out that the SGC-7901 cells nucleus of each drug administration group can be seen dispersion of low-density fluorescence,and with the growth of drug administration,the degree of fluorescent dye increases,where we can see the formative apoptotic body.Applying the flow cytometry to test apoptosis rate status after acting on SGC-7901 cells for 48h,which displayed that phycoerythrin is able to make SGC-7901 cells to apoptosis according to dose-dependent.When the dose is 5.2μM,the apoptosis rate is 24.5±1.64%.Use the flow cytometry to measure the cells periodic variation of different dosage phycoerythrin after acting on SGC-7901 cells for 24h,we can found out that cell count in Sphase distinctly increases with the growth of phycoerythrin dose.Comparing with the negative control group,phycoerythrin of low-dose group has a significant retardation effect on S-phase cells(P<0.05),and the middle and high dose groups have very obvious retardation effect on Sphase cells(P<0.01),which prompts cell count increase of DNA synthetic phase,thus the cell division process shall be accelerated and shortened.Applying the Western blot method to detect the expression of CyclinA,CDK2 and CDC25,which showed that different dose of phycoerythrin acting on human gastric cancer cell for 24h,the expression level of CyclinA significantly shall increase,which showed that the dose-dependent with the growth of administration dosage.Comparing with the negative control group,phycoerythrin of low-dose group has a significant increase effect on CyclinA expression level(P<0.05),and the middle and high dose group have very obvious increase effect on CyclinA expression level(P<0.01).CDK2 expression level distinctly decreases,which showed that the dose-dependent with the increase of dose administration.Comparing with the negative control group,phycoerythrin of low-dose group has a significant down effect on CDK2 expression level(P<0.05),and the middle and high dose group have very significant down effect on CDK2 expression level(P<0.01).The expression level of CDC25A declines significantly and has dose-dependent with the increase of administration dosage.Comparing with the negative control group,the middle and high dosage groups have very significant down effect on CDC25A expression level(P<0.01).From the above,phycoerythrin has a rather strong effect on restraining proliferation of human gastric cancer SGC-7901 cells,which is able to induce cells to apoptosis,and its mechanism has relation to the human gastric cancer SGC-7901 cells blocking in cell cycle Sphase after dosing.Through reducing CDC25A expression level,phycoerythrin can make CDK2 unable to be activated,so as to restrain the CyclinA/CDK2 complex activity and realize the S-phase period retardation to induce SGC-7901 cells apoptosis. |
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