Identification of URIM, a novel gene up-regulated in metastasis.

URIM (Up-Regulated In Metastasis) was identified as a new gene by Differential Display Technique during investigation of the transcriptional pattern of a metastasizing (NMCL-1) and a non-metastasizing (530) human melanoma cell line. The protein is encoded by 206 amino acids with an isoelectric point of 10.4. In addition, URIM displays a putative nuclear localization signal and a putative leucine zipper suggesting that URIM may function as a nuclear protein. Expression of URIM in several normal tissues and tumor cell lines was studied by Northern blotting. Surprisingly, 17 fold increased steady-state mRNA levels for URIM were detected in three cell lines derived from bone marrow micrometastasis of mammary carcinoma and one mammary carcinoma cell line derived from ascites fluid compared to normal epithelial cells from mammary gland and two cell lines derived from primary mammary carcinoma. These findings indicate that expression of URIM might be deregulated in metastases of different types of tumors.