Transcriptional and posttranscriptional activation of urokinase plasminogen activator gene expression in metastatic tumor cells.

Henderson BR, Tansey WP, Phillips SM, Ramshaw IA, Kefford RF
Cancer Res. 1992 52 (9): 2489-96

PMID: 1568219

Urokinase plasminogen activator (uPA) is a serine protease which has frequently been implicated in the process of tumor cell invasion and metastasis. The degree of expression and mode(s) of regulation of the uPA gene in metastatic compared with nonmetastatic tumor cells have not yet been addressed. We have cloned and sequenced a full-length rat uPA complementary DNA and utilized Northern blot analysis to report that the uPA gene is expressed at levels 3.5- to 70-fold higher in metastatic cell lines than in nonmetastatic cell lines derived from two independent rat mammary adenocarcinomas. Nuclear run-on assays and RNA half-life estimations indicated that metastatic MAT 13762 rat mammary adenocarcinoma cells expressed 3.5-fold higher levels of uPA RNA than a nonmetastatic derivative (J-clone), due to a combined increase in uPA gene transcription and cytoplasmic RNA stability. By contrast, uPA RNA (and enzyme) levels were elevated by up to 70-fold in metastatic clones of dimethylbenz(a)anthracene-induced rat mammary adenocarcinoma (DMBA-8) due to predominantly posttranscriptional mechanisms. Moreover, treatment of nonmetastatic DMBA-8 cell lines with protein synthesis inhibitors led to an increase in nuclear and cytoplasmic uPA RNA levels, without altering the rate of uPA gene transcription. These results suggest that in addition to gene transcription, posttranscriptional events localized in the nucleus and cytoplasm are key determinants of uPA gene activation in rat mammary adenocarcinomas.

MeSH Terms (17)

9,10-Dimethyl-1,2-benzanthracene Amino Acid Sequence Animals DNA Down-Regulation Enzyme Activation Female Gene Expression Regulation, Enzymologic Gene Expression Regulation, Neoplastic Mammary Neoplasms, Experimental Molecular Sequence Data Rats Rats, Inbred F344 RNA, Messenger Transcription, Genetic Transcriptional Activation Urokinase-Type Plasminogen Activator

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