Identification of aHoxc8-regulated transcriptional network in mouse embryo fibroblast cells

Abstract

The transcription factor, Hoxc8, is a member of the homeobox gene family that is vital for growth and differentiation. Previously, we identified 34 genes whose expression levels were changed at least 2-fold by forced expression of Hoxc8 in C57BL͞6J mouse embryo fibroblast cells using a mouse 16,463-gene oligonucleotide microarray. In the present study, we used the combined power of microarray profiling, global Hoxc8 DNA-binding site analysis, and high-throughput chromatin immunoprecipitation assays to identify direct and biologically relevant targets of Hoxc8 in vivo. Here we show that 19 of the 34 responsive genes contain Hoxc8 consensus DNA-binding sequence(s) in their regulatory regions. Chromatin immunoprecipitation analysis indicated that Hoxc8-DNA interaction was detected in five of the 19 candidate genes. All of these five target genes have been implicated in oncogenesis, cell adhesion, proliferation, and apoptosis. Overall, the genes described here should aid in the understanding of global regulatory networks of Hox genes and to provide valuable insight into the molecular basis of Hoxc8 in development and carcinogenesis.cancer ͉ chromatin immunoprecipitation ͉ Hox protein binding sites ͉ microarray

MicroRNA miR‐196a controls melanoma‐associated genes by regulating HOX‐C8 expression

“…6 One of those HOX transcription factors-HOX-C8-raised our attention as it was shown to regulate the expression of several target genes implicated in processes with relevance to tumorigenesis. [16][17][18] To elucidate if HOX-C8 is also a target for miR-196a in melanoma cells, we first determined HOX-C8 mRNA expression levels in our cell panel and found strongly enhanced expression (ranging from two-fold to about 18-fold) in the melanoma cell lines compared with NHEMs (Fig. 1b).…”

“…For this purpose, we selected a set of four genes-osteopontin, cadherin-11, calponin-1 and hugl-1-out of the HOX-C8 target genes described in literature. [16][17][18] We first determined mRNA expression levels of those genes in our panel of stable cell clones. We were able to detect significantly reduced Osteopontin mRNA levels (by about 50%; Fig.…”

“…Lei et al performed experiments involving cDNA microarrays and high-throughput chromatin immunoprecipitation assay on mouse embryo fibroblast cells overexpressing murine Hox-C8 and thereby identified a large cohort of Hox-C8 target genes. 16,17 Interestingly, genes implicated in mechanisms closely related to oncogenesis (such as cell adhesion, migration, proliferation and apoptosis) were significantly enriched in their set of target genes. We selected three of those genes-osteopontin, cadherin-11 and calponin-1-for further investigation in our melanoma cell lines.…”

“…However, for one of the HOXgenes targeted by miR-196a-namely HOX-C8-a set of target genes has already been characterized in more depth. [16][17][18] Strikingly, almost all of them are implicated in processes of major importance in tumorigenesis, such as cell adhesion, migration, differentiation and apoptosis.…”

Homeobox D10 Gene, a Candidate Tumor Suppressor, Is Downregulated through Promoter Hypermethylation and Associated with Gastric Carcinogenesis

“…It was accepted that Hox genes could regulate the promoter of genes by binding consensus elements TTAT, TAAT and TTAC. Combined with microarray profiling, DNA binding site analysis and chromatin immunoprecipitation (Chip) analysis identified that five genes are directly regulated by HoxC8 in mouse embryo fibroblast cells (27). These candidate genes have been implicated in oncogenesis, cell proliferation and cell apoptosis.…”