Cloning, Expression And Function Analysis Of Human Inhibitor Of Differentiation 3(Id3) In A549 Cells

Id(inhibitors of differentiation/DNA binding) proteins, which inhibit cell differentiation and promote cell proliferation, are negative regulators of basic helix-loop- helix (bHLH) type transcription factor. There are four related members of the Id family called Id1, Id2, Id3 and Id4 in mammalian cells.Id3 was originally identified as a serm-inducible immediate early gene in an established murine fibroblastic cell line. It involved in various biological processes including T and B cell development, skeletal muscle differentiation, vascular smooth muscle cell proliferation,embryonic neurogenesis ,osteogenesis and tumor -induced angiogenesis. Expression and function of this protein is under many complex layer of regulation. The expression patter of Id3 overlaps with but is not identical to that of Idl gene. It has different expression pattern in different kinds of cancer.The total cellular RNA were extracted from the peripheral blood mononuclear cell(PBMC) of the patients with hematologic disorders, PBMC from health adults and 8 human tumor cell lines(including Daudi,Jurkat,K562,U937,PC-3M,A549, BGC,COC2). The expression levels of Id2 and Id3 mRNA in PBMC and tumor cells were detected by RT-PCR technique. The results show that Id2 and Id3 mRNA have different expression levels in different cells. Id2 is widely expressed in many cell types, both in normal and malignant cells.The expression levels of Id3 mRNA in tumor cells and PBMC from hematologic disorder patients are significantly higher than which in healthy adult's PBMC.The expression levels of Id3 mRNA in different tumor cells have evident diversity. It seems that Id3 may play some important roles in the proliferation and differentiation of tumor cells, as well as in the development and growth of tumors.The human Id3 cDNA was amplified from human prostate cells PC-3M by RT-PCR technique and then was inserted into the pEGFP-N1 vector to construct the...