| ObjectiveGastric cancer is a common malignant cancer,and is the most frequently - occurring cancer in the digestive system. In our country, the incidence and the mortality of gastric cancer are the highest in malignant cancers. The invasion and metastasis is the main reason of failurein the treatment of patients. About thirty percent patients with solid tumor that is newly diagnosed have had the clinical metastasis. Therefore , how to prevent and treat invasion and metastasis becomes the focus in the study of cancerous treatment.Peritoneal metastasis constitutes forty to fifty percent or so after radical dissection of advanced gastric cancer. Its one of the main reasons that affect prognosis. At present CD44 and integrin among adhesion molecules are surely associated with peritoneal metastasis. CD44 is a family of transmembrane glycoproteins on cell surface and intermediates the adhesion of cell - cell, cell - matrix. If we interfere the interaction of CD44 and its ligand,then will find new targets that inhibit the growth and metastasis of cancer. The principle of antisense technique is based'on the base complementary principle,and is a technique using artificial or biological expressing DNA or UNA fragment (antisense nucleotides) to inhibit or close gene expression. With the further study,phosphothioate -modified oligodeoxynucleotides becomethe first successful oligonucleotide substitutes, because it has the water - solubility, stability of ribozyme splitting, easily synthesized. After li-posome carrying oligonucleotides into cells, it can protect oligonucle-otides splitting by ribozyme, prolong the effect in the nucleus, transform the distribution in cells.In this study,we designed a special oligonucleotide in accordance with CD44 gene sequence to observe the change of mRNA and protein expression after asODN acting on the cell line SGC7901, then detected the change of adhesion and invasion, observed the morphological change by transmission electron microscopy, thus affirmed that anti-sense technique is an effective way to obstruct metastasis.MethodsSGC7901 were cultured routinely with DMEM supplemented by 10% FCS. The distribution of ODN in cells was observed by histocyto-chemistry with Biotin - CD44 asODN. The change of protein expression was detected by immunohistochemistry. ODN were transfected into SGC7901, taking liposome as vector. Changes in the expression of CD44 mRNA, protein, adhesion and invasion to ECM were determined by RT - PCR, FCM, MTT and polycarbonate filters respectively. Ultra-microscopic structure was observed by transmission electron microscopy. All the data were analyzed by SPSS10. 0 software.Results1. There was no obviously change in cytoplasm and nucleus three hours after CD44 asODN was transfected into SGC7901, appeared light brown pellets in cells six hours later. 2. The expression of CD44 protein decreased after thirty - six hours. 3. CD44/P - actin mRNA rela-live quantitative ratio (0.641 ±0.084) of asODN groups was obviously lower than that(0.894 ±0.120) of control groups( P < 0.05). 4. The mean fluorescent index(2.087 ±0.577) of asODN groups detected by FCM was evidently decreased than that (5. 283 ± 1. 783) of control groups(P < 0.05 ). 5. The adhesive ability of asODN groups( 0.159 ± 0. 025 ) obviously declined compared with control groups ( 0. 294 ± 0.058) ( P < 0. 01). 6. There was marked difference between asODN groups(7. 5 ± 1. 291 ) and control groups ( 15. 75 ± 1. 708) on the number of cells that infiltrate the polycarbonate membrane ( P < 0.01). 7. Being treated with asODN, there were fewer pseudopodia and globular processes on the cancer cell surface. But there was no difference between the above mentioned indexes of rODN groups and that of control groups.Conclusion1. Liposome did transfect phosphorothioate - modified asODN into SGC7901.2. Transfection of CD44 asODN into SGC7901 induced a decrease in the expression of CD44 mRNA and protein, thus a decrease in adhesion and invasion to ECM, with a better effect than rODN. 3. The...
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