Expression Of Apoptotic Factor Caspase-3 In Female Non-small Cell Lung Cancer

PREFACELung cancer is one of the most common malignancies. The etiology and pathogenesis of lung cancer remain unclear, but several studies suggest a prominent role for the activated proteinase in the development of lung cancer.Apoptosis is a major form of cell death, characterized, initially, by a series of stereotypic morphological changes. In the nematode Caenorhabditis elegans, the gene ced - 3 encodes a protein required for the development cell death. It is now known that CED - 3 has sequence identity with the mammalian cysteine protease (Interleuktin - 1β - converting enzyme). At least 10 kinds of this protease have been identified in mammalian cysteine family. These proteins are characterized by almost absolute specificity for aspartic acid in the p - 1 position. All the caspases (ICE - lile proteases) contain a conserved QACXG pentapeptide active site motif. Caspases are synthesized as inactive proenzymes comprising an N - terminal peptide ( prodomain) together with one large and one small sub-unit. The crystal structures of both caspase - 1 and caspase -3 show that the active enzyme is a heterotetramer, containing two small and two large subunits. Activation of caspases during apoptosis results in the cleavage of important substrates in the cells. These substrates include poly( ADP - ribose) polymerase and lamins, and the cleavage promotes the dramatic morphological changes of apoptosis.Some observations suggest that activation of caspase - 3 is highly associated with proliferation and differentiation of the cells in lung cancer. Our experimenthas detected the expression of caspase - 3 protein in human lung cancer and their corresponding tissue, to analyse the relationship between the expression of caspase -3 and clinical histopathological characteristics. Our objective is to assess the significance of caspase - 3 in tumorigenesis and progression of lung cancer.Materials and Methods1. Materials1.1 Specimens:66 lung cancer and their corresponding specimens were used in western blot study. These cases were obtained from LiaoNing provincil hospital for tumor from 2003 -2004. All the cases were non - small cell lung cancer of female patients who had surgery but without other therapies.1. 2 Major reagent and sources:Mouse monoclonal IgG2αantibody for caspase - 3 ( sc - 7272) and Alkaline Phosphatase Horse Anti - Mouse IgG ( H + L) were purchased from Beijing ZhongShan Biotechnology Company. NBT/BCIP kit was purchased from HuaMei Company. Prestained Protein Mark ( broad range) were purchased from Sigma Biotechnology Company. Proteinase inhibitor Aprotinin,Leupeptin, Sodium or-thovanadate,PMSF were purchased from Beijing ZhongShan Biotechnology Company.1. 3 Apparatus:Spectrophotometer, centrifugal machine and electrophoresis apparatus were used as major apparatus.2. Methods2.1 Protein abstraction; The tissue was flushed with cooled PBS; cut the tissue to be smashed and added with lysate; homogenate and transonic were formed after misce bene; supernatant abstract.2.2 Protein detection: Do according to Brandford method, calf serum protein being the standard.2. 3 Western blot: Proteindenaturation; SDS - PAGE electropho - resiswith equal quantity protein; transfer the protein to pyroxylin; blockage; antibody allomixis; NBT/BCIP coloration; image.2.4 Statistics: Quality data is analysed with X2 - test by SPSS 1.0. 0 software, the difference is significant if p <0.05.Result39. 39% of specimens taken from cancerous cells and 74. 24% of specimens taken from non - cancerous cells expressed positive results. The difference was statistically significant; positive expression of caspase - 3 is related to the degree of metastasis to lymph nodes and the degree of differentiation; caspase -3 expression has no significant relationship with age,lymph node stages,TNM stages and histopathological stages.DiscussionApoptosis also named programmed cell death - PCD is the active process of cell suicide controlled by gene code. Proliferation and apoptosis of cell is the base of maintaining body stabilization. The body eliminates ageing, aberration and disease causing cells through apoptosis. Studies show that if apoptosis is inhibited , malignancy proliferates without limit. Through the decrease of apoptosis and/or increase cleavage. Tumor cell down regulation of apoptosis related gene through complex mechanism. Recently several studies show that caspase family had a major role in apoptosis. When apoptosis the inactive procaspases collect and activate by themselves. The activate caspase can promote apoptosis mechanism.There are more than 14 caspases have been found. At least two thirds are involved in physiological or pathological process of apoptosis. Caspase - 3 is the most important member of apoptosis. Most initiate factors induce apoptosis through caspase - 3 mediate signal transducing pathways.The data of Western blot presented here suggest that levels of caspase - 3 is increased in female lung cancer compared with their corresponding adjacent nor-...