title: Id-1 expression and cell survival.
abstract: The Id (inhibitor of differentiation or DNA binding) helix-loop-helix (HLH) proteins are a group of dominant negative regulators of basic HLH transcriptional factors which promote cell differentiation. Recent evidence has revealed that Id proteins, especially Id-1, are also able to promote cell proliferation and cell cycle progression through inactivation of tumour suppressor and activation of growth promoting pathways in mammalian cells. In addition, upregulation of Id-1 has been found in many types of human cancer and its expression levels are also associated with advanced tumour stage. Furthermore, ectopic expression of Id-1 in human cancer cells is able to induce cell proliferation under sub-optimal conditions and protect the cells against apoptosis. These lines of evidence strongly indicate Id-1 as a positive regulator of cell growth and its expression may be a key factor required for tumour cell proliferation. This review will discuss recent evidence on the role of Id-1 in cell proliferation and survival, and its significance in malignant transformation. In addition, we will highlight the recent development in the understanding of the molecular mechanisms responsible for the action of Id-1 in promoting cell survival and tumourigenesis. Finally, the therapeutic implications through inactivation of Id-1 in the treatment of human cancer will also be addressed.
authors.affiliation: Department of Anatomy, Cancer Biology Lab, Faculty of Medicine, and Central Laboratory of Institute of Molecular Technology for Drug Discovery and Synthesis, The University of Hong Kong, 21 Sassoon Road, Hong Kong, SAR, China. ycwong@hkuc.hku.hk
authors.forename: Y-C
authors.initials: YC
authors.lastname: Wong
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: M-T
authors.initials: MT
authors.lastname: Ling
mesh_terms: D000818:Animals; D017209:Apoptosis; D002453:Cell Cycle; D002454:Cell Differentiation; D002455:Cell Division; D002468:Cell Physiological Phenomena; D002470:Cell Survival; D002471:Cell Transformation, Neoplastic; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D051798:Inhibitor of Differentiation Protein 1; D008954:Models, Biological; D009367:Neoplasm Staging; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D004268:DNA-Binding Proteins; C497453:ID1 protein, human; D051798:Inhibitor of Differentiation Protein 1; D012097:Repressor Proteins; D014157:Transcription Factors