Monitoring Gene Expression Profile Changes In Human Bladder Transitional Cell Carcinoma Using CDNA Microarray

Bladder carcinoma has become the most frequent and lethal cancer from urogenital system in our country. The etiology of bladder cancer is still unknown. Earlier diagnosis helps to cure the disease, but the cancer is easy to recur after operation. There is clearly a need for novel more effective diagnostic and therapeutic methods. The Human Genome Project(HGP) is the most important biology project that has ever been undertaken, it aims to sequence the 3×109bp nucleotide sequence of human genome and identify all the estimated 70,000-100,000 genes. Although sequencing of the human genome will soon be completed, gene identification and annotation remains a challenge. Identifying and sequencing a set of full-length cDNAs that represent all human genes would help in both gene discovery and functional analysis. Constructing a high-quality eDNA library with good representation of full-length cDNAs is very important for full-length cDNA cloning. From a high-quality eDNA library constructed by our laboratory, we have obtained thousands of human new full-length cDNAs by high efficiency subtraction and large-scale cDNA sequencing. Some of the new full-length cDNAs have been submitted to the GenBank. Part of the full-length and partial cDNAs representing known, novel and control genes cloned from the cDNA library was used to construct eDNA microarrays. Microarray analysis on a genomic scale was used to monitor profile changes in gene expression accompanying human transitional cell carcinoma(TCC). Ten patients were screened for expression of 12,800 human genes. The hybridizations for each individual were repeated twice. According the results of hybridization to the microarray with Cy3-labeled cDNA probe from normal bladder 6 and Cy5-labeled eDNA probe from TCC, 854 genes (7%), whose ratios of Cy5/Cy3 were higher than 2.0 or lower than 0.5, were screened out after 10 couples of hybridizations. In the cancerous tissue 198 of them showed higher expression and 656 lower. 576 genes (67.4%) are already known and registered in GenBank. However, if we took 4.0 folds as the base line of significant difference, there were 384 differential expressed genes(3%), among which 87 showed higher expression in the cancerous tissue and 297 lower. These differentially expressed genes are always involved in the physiological processes such as signal transduction, apoptosis and cell cycle, etc. The overexpressed genes in TCC include: ~D signal-transduction-related genes: (PTK-related gene; G-protein; intracellular kinase; second messenger; calmodulin); ヽell-cycle-related gene; 畉umor-metastasis-related gene; (I~)apoptosis inhibition gene; ~mitochondria-related gene. The downexpressed genes in TCC include: 0 apoptosis-related gene; ?PTP(protein tyrosine phosphatase)-related genes; ? adherent-molecule-related gene (fibronectin; laminin; collagen); OTGF- P -related gene; ﹖umor suppression gene; ﹝inc finger protein gene. There were 125 novel genes unregistered in GenBank showing obvious difference greater than 4 folds between Cy3 and Cy5 signals. The study shows that TCC cells are much more active than normal cells in many steps of multiple pathways of signal transduction. The stable state of normal somatic cells depends on the dynamic equilibrium of apoptosis and proliferation. apoptosis-related gene was down-expressed in TCC, while some of the apoptosis-suppr...