| Colorectal cancinoma is one of the most terrible diseases in the world. The incidence and mortality are climbing with the changes of life style and diet configuration. It is thought to develop from adenoma step by step with altered expression of many genes, such as activation of oncogenes and inactivation of tumor suppressor genes. Though we have done much to conquer the adversary, it still makes way without any effective obstruction. Thus, synthetical analysis of all genes concerned with the initiation and progression would be required to understand every aspect of colorectal cancer.Reg gene was first reported in 1988 by a Japanese. It was intitled as regenerating gene because of its function in regenerating course of islet beta cells in a 90% depancreatized rat. It is also named as pancreatic stone protein(PSP) and pancreatic thread protein(PTP). Some reg related genes constitute a multigene family. Reg4 is a new one in the family and was isolated from an IBD (inflammatory bowel disease ) cDNA library in 2001. Till now, it is the shortest one of reg family, encoding a secreted protein with 158 amino acids, and a signal peptide of 21 amino acids. The molecular weight is 17KD.In our lab, three cDNA libraries of A-N, T-N, T-A had been constructed in 1999,using the tissues taken from one patient with suppression subtractive hybridization (SSH). In A-N library, a frequently selected sequence was found to be 100% homologous to the protein product of Reg4. RT-PCR and Northern blot were performed to detect mRNA levels in paired normal, adenoma and cancer tissues. We found that mRNA levels were higher in adenomas and carcinomas compared wih that of normal tissues, in addition, the mRNA level was much more higher in adenomas than in carcinomas. The result indicates that Reg4 maybe is a biomarker of carcinogenesis.In this study, immunohistochemistry staining, immune electron microscopy were performed to detect the protein expression and localization of Reg4. We found that Reg4 differentially expresses in gastrointestinal tract, such as stomach, intestine, colorectum and appendix, while in pancreas, heart, liver, parotid, prostate, thyroid gland, tonsil, spinal cord, brain, urinary bladder, it is negative. In normal gastrointestinal tissue, there are two different cell types showing positive staining of Reg4, one is exocrine epithelium according to its figure and characteristics of mucin staining, while the other one is considered as endocrine cell because of its exterior similarity with neuroendocrine cell. But considering its noncolocalization with CgA and its low positive ratio in carcinoid, especially its subcellular localization, we can ensure that it is not a marker of neuroendocrine cell. On the contrary, the expression of Reg4 was decreased in the sequence of normal-adenoma-carcinoma, it is somewhat correlated with differentiation of colorectal tissue, so we presume that Reg4 positive cell has an unknown relationship with gastrointestinal stem cells.Bioinformatics is a useful method to collect any interested information which is difficult to obtain by lab work in limited time and financial support. We did somework in 3D structures of 4 mankind Reg proteins, Reglα, Reglβ, Reg3 and Reg4, with the help of some online services and softwares, such as NCBI, swiss-pdbviewer,CPH-model, clustalx, DNAStar, et al. The basic amino acids sequences and structure alignments all support the 4 mankind Reg proteins' conservation in evolution and their analogical functions.
|
PDF Full Text Request