ABSTRACT
Caveolin-1 (CAV1) is over-expressed in prostate cancer (PCa) and is associated with adverse prognosis, but the molecular mechanisms linking CAV1 expression to disease progression are poorly understood. Extensive gene expression correlation analysis, quantitative multiplex imaging of clinical samples, and analysis of the CAV1-dependent transcriptome, supported that CAV1 re-programmes TGFß signalling from tumour suppressive to oncogenic (i.e. induction of SLUG, PAI-1 and suppression of CDH1, DSP, CDKN1A). Supporting such a role, CAV1 knockdown led to growth arrest and inhibition of cell invasion in prostate cancer cell lines. Rationalized RNAi screening and high-content microscopy in search for CAV1 upstream regulators revealed integrin beta1 (ITGB1) and integrin associated proteins as CAV1 regulators. Our work suggests TGFß signalling and beta1 integrins as potential therapeutic targets in PCa over-expressing CAV1, and contributes to better understand the paradoxical dual role of TGFß in tumour biology.
Subject(s)
Caveolin 1/metabolism , Gene Expression Regulation, Neoplastic , Intracellular Signaling Peptides and Proteins/metabolism , Membrane Proteins/metabolism , Prostatic Neoplasms/metabolism , Transforming Growth Factor beta1/metabolism , Adaptor Proteins, Signal Transducing , Cell Line, Tumor , Humans , Male , Oncogenes , Phenotype , Prostatic Neoplasms/genetics , Signal Transduction , Up-RegulationABSTRACT
Hypoxia inducible transcription factors (HIF) are mainly regulated by a group of proline hydroxylases (EGLNs) that, in the presence of oxygen, target HIF for degradation. HIFalpha contains two independent oxygen degradation domains (N-ODD and C-ODD) that are substrates for these enzymes. In this work, we employed the yeast two-hybrid assay to study the sequence determinants required for the binding of EGLN1 and 3 to HIF1alpha in a cellular context. Our results demonstrate that, while EGLN1 is able to recognize both ODDs within full length HIF1alpha protein, EGLN3 only binds to CODD. The analysis of the residue substitutions within CODD uncovered novel critical determinants for EGLN1 and 3 binding. In addition, our results show that both enzymes have a very similar, albeit not identical, residue preference at specific positions in their substrate sequences.
