| Gastric cancer is a kind of malignant tumor that occurs in gastric epithelial tissue. It is estimated that every year more than80million patients are suffered from gastric cancer, probably accounting for about9%of newly diagnosed cancers, after lung, breast and colon cancer, ranking the fourth most prevalent cancer, with an annual mortality rate of approximately60million, probably second only to lung cancer as the leading cause of cancer-related death worldwide. Early gastric cancer is of good prognosis,5-year relative survivals up to90%. When muscle layer invasion is present,5-year survival is40%to50%postoperative and is only10%when the lesions invading the serosa or outside, so the adjuvant chemotherapy of gastric cancer occupies an important position. It is an aggressive cancer that is often not diagnosed until an advanced stage, for we do not effectively carry out gastric cancer screening, patients with advanced GC have a relatively poor prognosis with a5-year survival less than10%. Surgical resection is the mainstay of curative treatment, and treatment strategies in gastric cancer incorporate a multidisciplinary approach and require the co-operation of gastroenterologists, surgeons, medical and radiation oncologists, pathologists and radiologists. Once the cancer found to infiltrate or metastasize, surgery is often palliative chemotherapy in treatment as the preferred treatment option is adjuvant chemotherapy in order to improve patients’quality of life and prolong survival time. Since the1960s, fluorouracil (5-FU) was used for gastric cancer treatment, the development of gastric cancer in first-line combination chemotherapy regimens had experienced the evolution of FAMâ†'FAMTXâ†'FPâ†'ECF within40years.5-FU becomes the classic and basic drug in the first-line chemotherapy regimens. Multidrug resistance caused primary or secondary are not sensitive to chemotherapeutic drugs, often affect the effectiveness of chemotherapy and the total efficiency of20%to58%, as to advanced gastric cancer the median survival time is not more than10months. So chemotherapy resistance becomes one of the most common and difficult problem in clinical, which has a long way to go.Micro-RNA are a group of highly conserved small RNA in evolution in eukaryotes, which are single-stranded and consist of approximately22nucleotides. They do not code for any protein or peptide; however, they regulate gene expression or translation involved in regulating cell development, proliferation, differentiation, and apoptosis. Micro-RNA with tumor suppressor activity and oncogenic activity have important roles in the development, invasion, metastasis and treatment of digestive tract tumor.The latest study found that micro-RNA closely related to tumor including gastric cancer and provides a new direction in the study of chemotherapy resistance. Partâ… Establishment of5-Fluorouracil Resistant Human Stomach Cancer Cell Line SGC-7901/5-FU and Analysis of Biological PropertiesObjective:To establish the5-fluorouracil (5-FU)-resistant stomach cancer cell line SGC-7901/5-FU with its biological characteristics studied. Methods:the5-FU-resistant stomach cancer cell line SGC-7901/5-FU was established by repeatedly exposing stomach cancer cell line SGC-7901to increased gradually concentration of5-FU. Cell growth curve was painted and the doubling time was accouted by cell counting assay. The resistant index of the resistant cell line to different chemotherapy drugs was determined by the methyl thiazolyl tetrazolium assay (MTT).The protein expression levels of P-ga of the drug-resistant and parental cells were determined by Western-blot. The mRNA expression levels of MDRP were determined by realtime-PCR. Results:The5-FU-resistant human stomach cancer cell line SGC-7901/5-FU was established after8months. The resistant cell line was slow in proliferation, the doubling time was extended by5.7hours than the parental cell line The drug resistant index being8.2, but are not cross-resistant to Cisplatin (CDDP), Adriamycin (ADR). The resistant cell line expressed the P-ga, while the parental cells not. MDRP (multidrug resistance protein) mRNA expression was18times more than the parental cell line. Conclusions:This study established a human gastric cancer5-fluorouracil resistant cell lines SGC-7901/5-FU, its biological properties different from the parental cell line SGC-7901, with the basic biological characteristics of drug-resistant cell lines, can be used for downstream experiment. Part â…ˇMicroarray analysis of the parental and resistant cell lines of micro-RNA expression profileObjective:To analyze micro-RNA expression profiles in the human gastric carcinoma parental cell line SGC-7901and SGC-7901/5-FU resistant cell lines and screen the differentially expr -essed micro-RNA. Methods:micro-RNA array was used to analyze micro-RNA expression profile. Real-time PCR was used to validate the result of micro-RNA expression change from micro-RNA array analysis. Results:Compared with SGC7901cells,4micro-RNA were up-regulated more than2-fold(microRNA190, microRNA142-5p, microRNA668, micro-RNA-501-5p), and2micro-RNA were down-regulated more than2-fold (microRNA197, micro RNA210) in SGC7901/5-FU cells. Micro-RNA190was confirmed up expressed in SGC7901/5-FU cells by real-time PCR. Conclusions:the multidrug resistance characteristic in SGC-7901/5-FU resistant cells may be related to micro-RNA expression profile changes, providing a new research direction to solve the multidrug resistance of tumor chemotherapy. |
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