Prelimenary Studies On Effects Of Cellular Adhesion Tripeptide RGD On Inhibiting Growth Of HCT-8 And Inducing Its Apoptosis

The tripeptide, Arg-Gly-Asp (RGD) motif is an integrin-recognitionsite found in adhesive proteins present in extracellular matrices (ECM)and in blood. RGD and some synthetic RGD-containing peptides ascompetitive, reversible inhibitors for adhesive proteins binding have beenwidely used to study adhesive interaction between cells and suppresstumor metastasis etc. Recently, it has been also reported that RGD canenter the cells directly and induce apoptosis by activating some membersof caspase family. It attracts more and more attention of researchers onstudying the effect of RGD on inducing apoptosis of tumor cells.Apoptosis is a natural and physiological process. It is decided bygene and it is also called programmed cell death. Apoptosis and necrosisare different cytological-phenomenon. During the apoptosis, conformity ofmembrane is all right and many apoptotic bodies can be formed. Contentof dead cells will not escape out to extracellular environment to result ininflammation. On other way round, when necrosis happend, cell is swolnand membrane broke. It results in content of cells coming out and causinginflammation. So inducing apoptosis of tumor cells not only can kill tumorbut also will not arise inflammation to injure other organ. This studyprovides a new way of exploring anti-tumor drugs.Recently, it has been reported that RGD can kill human prostatecancer cells (TSU), glomerular mesangial cells from adult human kidneys(GMC) and human leucocythemia cells (HL-60). This study armed toinvestigate the inhibitory effect of RGD on growth and proliferation ofhuman ileocecal adenocarcinoma cells HCT-8 and induced apoptosis. Wetest the proliferation of HCT-8 cells by the MTT assay and observe cellmorphological feature and ultramicroscopic structure of apoptotic cells.We find RGD can inhibit proliferation of HCT-8 cells by inducing itapoptosis. To approve it further, flow cytometry analysis andelectrophoresis of DNA are done to test apoptosis. We can find a apoptoticpeak. With increasing the concentration of RGD, proportion of apoptoticpeak increased. In the figure of electrophoresis of DNA, there is a typicalDNA ladder of apoptotic cells. These results indicate that RGD doesinduce apoptosis of HCT-8 cells and the RGD concentration of 37.5μg/mlis the best condition. In addition, we display anti-apoptosis proteinSurvivin in cells by way of immunohistochemistry staining and find thatRGD can inhibit expression of Survivin. It suggests that it may be amechanism of RGD inducing apoptosis. We would do more study toapprove this point later.Nowadays, it has attracted much attention that RGD can directlyenter into cells and induce apoptosis. But study on this field is still notenough. So our study can base the theory of cure of tumor by RGD.