| Baldder cancer is one of the most common tumor in urinary system. It is the fifth most common cancer in the Western world, affecting 4% of all cancer patients, and is the cause of 2% of all cancer-related deaths, It is estimated that, in 2000, approximately 31200 Americans received a diagnosis of bladder cancer and 12200 died of this disease. Both invasion and recurrence are the major reasons that limited the therapeutic prognosis of bladder cancer.With the development of molecular biology and its application in study of tumorrigenesis, it has been demonstrated that the development of malignant tumors is due to the activation of protooncogenes and inactivation of tumor suppressor genes leading to loss of control on cell proliferation and apoptosis. Cancer can be regarded as a gene disease, and will be treated in molecular level to correct the mistakes of genes in the tumor cell, through to restrain the expression of oncogene and to increase the expression of antioncogene.Formerly molecular genetic studies of bladder cancer have implicated severalchromosal regions as the target sites for genetic alterations. Frequent allelic losses have been detected on chromosomes 4p, 8p, 9p, 9q, 10q, lip and 17p. p53 and p16 have been identified as a tumor suppressor gene. Recently, a new gene was cloned from a homozygously deleted region on 10q23.3 in tumor, and it is named as PTEN. The PTEN gene has some characters such as: 1. Mutated in multiple advanced cancers. 2. Phophatase and tensin homolog. 3. Transforming growth factor- 3 -regulated and epithelial cell-enriched phosphtase. PTEN is frequently deleted or mutated in a variety of advanced cancers, including malignant melanoma, and cancers of the brain, breast, endometrium, prostate, thyroid, head and neck, ovary, pancreas, bladder, and colon. PTEN, regarded as a new tumor suppressor gene, is not only a homologous with the protein tyrosine phosphatase (PTP) family and with the cytoskeletal protein tensin, but also a dual-specificity phosphatase, the protein can dephosphorylate substrates phosphorylated on serine, threonine, and tyrosine, and can modulate cell signaling transduction. Function for PTEN have been identified in the regulation of many cell processes, including growth, adhesion, migration, invasion and apoptosis. The study on PTEN, a novel gene, in bladder cancer has been beginning, PTEN mutation in bladder cancer have been reported abroad, but the reports of PTEN in bladder has not been found in our country.We transfected WT-PTEN and DN-PTEN(mutated) cDNA to bladder cell line EJ, and investigated its anti-tumor effects and PTEN mediated sensitization of the bladder cancer to chemotherapy. Through the detection of the PTEN mutation in baldder cancer tissues, we think PTEN mutation is not common in baldder cancer. We also detected PTEN and Bcl-2 expression analysis in baldder cancer tissues.Part IThe study on the effect of WT-PTEN gene on the behavior of bladder cancer cellsThe plasmids pSvEGFP-PTEN (phosphatase active), pSvEGFP-C 124A(phsophatase-null) and pSvEGFP (empty), which have not antibiotics selection marker, and the empty vector plasmid p-IRSE-Vector with Amp and Hyg resistance were replicated in bacteria and purified. The plasmids pSvEGFP-PTEN, pSvEGFP-C124A, pSvEGFP were transfected together with p-IRSE-Vector respectively into human bladder cell line EJ by lipofectAMIN transfection. Green positive transfected cell clones EJ-pSvEGFP-PTEN ( WT-PTEN ) , EJ-pSvEGFP-C124A ( DN-PTEN ) and EJ-pSvEGFP were selected out by Hyg(Hygromycin). Further more the protein expression were also detected by immunohistochemstry and Western blot to certify that the plasimds could expressed effectively in EJ cells.We observed the growth rate of EJ-pSvEGFP-PTEN with PTEN overexpression was lower than other cells, and it decreased by 42.7%( P<0.01) in 6th day, no difference was observed among EJ-pSvEGFP-C124A, EJ-pSvEGFP and EJ cells (P>0.05). Clones with high expression of WT-PTEN showed decreased proliferation than other cells by MTT metho...
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