ABSTRACT
Cell migration is essential to cancer invasion and metastasis and is spatially and temporally integrated through transcriptionally dependent and independent mechanisms. As cell migration is studied in vitro, it is important to identify genes that both drive cell migration and are biologically relevant in promoting invasion and metastasis in patients with cancer. Here, gene expression profiling and a high-throughput cell migration system answers this question in human bladder cancer. In vitro migration rates of 40 microarray-profiled human bladder cancer cell lines were measured by radial migration assay. Genes whose expression was either directly or inversely associated with cell migration rate were identified and subsequently evaluated for their association with cancer stage in 61 patients. This analysis identified genes known to be associated with cell invasion such as versican, and novel ones, including metallothionein 1E (MT1E) and nicotinamide N-methyltransferase (NNMT), whose expression correlated positively with cancer cell migration and tumor stage. Using loss of function analysis, we show that MT1E and NNMT are necessary for cancer cell migration. These studies provide a general approach to identify the clinically relevant genes in cancer cell migration and mechanistically implicate two novel genes in this process in human bladder cancer.
Subject(s)
Cell Movement , Metallothionein/metabolism , Nicotinamide N-Methyltransferase/metabolism , Urinary Bladder Neoplasms/metabolism , Urinary Bladder Neoplasms/pathology , Cell Proliferation , Extracellular Matrix/metabolism , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Humans , Metallothionein/genetics , Neoplasm Invasiveness , Neoplasm Staging , Nicotinamide N-Methyltransferase/genetics , RNA, Small Interfering/genetics , Substrate Specificity , Urinary Bladder Neoplasms/genetics , Wound HealingABSTRACT
Expression profiling by DNA microarray analysis has provided insights into molecular alterations that underpin cancer progression and metastasis. Although differential expression of microarray-defined probes can be related to numerical or structural chromosomal alterations, it is unclear if such changes are also clustered in distinct chromosomes or genomic regions and whether chromosomal alterations always reflect changes in gene expression. Here we apply the dChip algorithm and a novel technique to test the hypothesis that expression changes occurring as a function of tumor progression and metastasis are nonrandomly distributed. Expression profiling of a human xenograft model of lung metastasis phenotype indicates that chromosomes 2, 11, and 20 contain higher percentages of differentially expressed genes (P < .05). Furthermore, we show that a number of differentially expressed probes mapped to chromosome 17q, defining the existence of an expression "hot spot" corresponding to an area of gain determined by comparative genomic hybridization (CGH). Interestingly, other areas of gains detected by CGH were not associated with expression hot spots. In summary, we show that gene expression changes during bladder cancer lung metastasis occur nonrandomly in specific chromosomes and intrachromosomal locations.
