Expression of homeobox-containing genes in primary and metastatic colorectal cancer.

Homeobox genes are a network of genes encoding nuclear proteins functioning as transcriptional regulators. Human and murine homeobox genes of the HOX family are organised in four clusters on different chromosomes. Gene order within each cluster is highly conserved, perhaps in direct relation to their expression. Homeobox genes have recently been involved in normal development and oncogenesis. We have analysed HOX gene expression in normal human colon and in primary and metastatic colorectal carcinomas. The majority of HOX genes are active in normal adult colon and their overall expression pattern is characteristic of this organ. Furthermore, the expression of some HOX genes is identical in normal and neoplastic colon indicating that these genes may exert an organ-specific function. In contrast, other HOX genes exhibit altered expression in primary colon cancers and their hepatic metastases which may suggest an association with colon cancer progression.