Transforming activity of MECT1-MAML2 fusion oncoprotein is mediated by constitutive CREB activation.

Salivary gland tumors, a group of histologically diverse benign and malignant neoplasms, represent a challenging problem for diagnosis and treatment. A specific recurring t(11;19)(q21;p13) translocation is associated with two types of salivary gland tumors, mucoepidermoid carcinomas and Warthin's tumors. This translocation generates a fusion protein comprised of the N-terminal CREB ...
(cAMP response element-binding protein)-binding domain of the CREB regulator MECT1 (Mucoepidermoid carcinoma translocated-1) and the C-terminal transcriptional activation domain of the Notch coactivator Mastermind-like 2 (MAML2). Here, we demonstrate that the MECT1-MAML2 fusion protein induces expression of multiple genes known to be CREB transcriptional targets. MECT1-MAML2 was found to bind to CREB, recruit p300/CBP into the CREB complex through a binding domain on MAML2, and constitutively activate CREB-dependent transcription. The transforming activity of MECT1-MAML2 was markedly reduced by blocking CREB DNA binding. Thus, this fusion oncogene mimics constitutive activation of cAMP signaling, by activating CREB directly. This study has identified a novel, critical mechanism of transformation for an oncogene associated very specifically with salivary gland tumors, and identified potential targets for the development of novel therapies.
Mesh Terms:
Cell Cycle, Cell Line, Cell Transformation, Neoplastic, Cyclic AMP, Cyclic AMP Response Element-Binding Protein, Humans, Nuclear Proteins, Oligonucleotide Array Sequence Analysis, Oncogene Proteins, Fusion, Protein Structure, Tertiary, Signal Transduction, Trans-Activators, Transcription Factors, Transcription, Genetic
EMBO J.
Date: Jul. 06, 2005
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