| Objective: Human Colorectal adenocarcinoma (HCRC) is a cammon malignant tumor. Compared with other cammon cancers, It is characterized by multi-primary tumor tendency and to some extent genetic tendency. It is the multi-gene mutations steps in the process of occurrence and development. It has been happened that there are abnormal cell division and indifferentiatioa There are also some interaction among proteins. It is very important to study genes differential expression in the HCRC. Furthermore, the study will support some references to explore molecular mechanism of HCRC.Filtering through suppression subtractive hybridization and cDNA chip technique, we found that the EST segments of CK570304 and BM360862 showed the expression in rectum adenocarcinoma tissue was higher than in normal Colorectal tissue on gene chips. To further study the relationships with HCRC, this experiment studied the level of expression of the two genes, so as to offer some informations for studying etiopathogenesis of rectum adenocarcinoma.Methods: In this experiment we selected the EST of BM360862 as seeded sequence and utilized the method of bioinformatics to clone full-length cDNA from the EST fragment. It was predicted the chromosome location, tissue distribution, genetic orgenization expression pedigree, protein' s homology, protein' s secondary structure and subcellular location. The experiment of RT-PCR and sequence analysis was employed to validate the contig. Then, the full-length cDNA sequence was submitted Genebank and acquired accession number which is AY743663. We alsodetected the expression of AY743663 in rectum adenocarcinoma tissue and the normal rectum tissue through Real-time PCR.The gene symbolized by CK570304 is the known Calmodulin (CaM), which is the crucial receptor of Ca2+ in the cell. CaM is not only concerned with regulating numerous physiological and biochemical courses, but also plays an important role in cell proliferation, movement, differentiation, transformation and microtubule asserrbly, especially in cell cycle, the level of CaM increasing expression is a necessory condition that the cell enters into the cell cycle, such as from Goto Giperiod, from G( to S period, from G> to M period and from mid period of M to late period We also made a preliminary analysis for the expression of CaM in rectum adenocarcinoma tissue and normal rectum tissue through Real-time PCR and RT-PCR..Results: The novel gene AY743663 exists in 10q25-q26. It has a CULLIN domain among 137-270 amino acid and shows high homeology with protein of cullin-3. The result of Real-time PCR showed that the level of expression of the novel gene AY43663 in rectum carcinoma tissue is higher than in normal rectum tissue. RT-PCR and Real-time PCR for the gene CaM shows that the level of expression in rectum carcinoma tissue is higher than in normal rectum tissue.Conclusion: The protein coded by the novel gene AY743663 has a CULLIN domain among 137-270 amino acid and has high homeology with protein of cullin-3. This irrplied the production of the novel gene probably has a familiar physiological function with cullirr3. Moreover, protein of cullin-3 targets cyclinE for ubiquitination degradatioa It is helpful to form pre-replication complex by degrading cyclinE. Therefore, the increasing expression of AY743663 contributes to cell division and proliferatioa The novel gene AY743663 is found that its expression in rectum adenocarcinoma tissue is higher than in normal rectum tissue. Thus possibly have the familiar functioa CaM adjusts the cell cycle on threepositions from Gl to S, G2 to M and the mid period of M to the late period. So CaM hastens the cell cycle and proliferation, its increasing expression relates to malignant transformation of the cell.
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