Abstract
Multiple myeloma (MM) is one of malignant plasmacyte neoplasm in hematopietic system. Although nearly 70% patients of myeloma response to chemotherapy, but repeated therapies will induce drug resistance soon and lead to refractory or relapsed myelomas. In recent years, thalidomide is used to treat relapsed and refractory myeloma with satisfied effects and overall therapeutic rate with thalidomide is about 60%. Furthermore, the adverse effects of thalidomide is slight without myelosuppression, hepatotoxicity and renal toxicity. So thalidomide is likely to be a prospective antitumor agent. However, the mechanism of antitumor activity of the agent is still not clear. DNA microarray technology has provided us a very useful method to detect simultaneously the expression pattern of thousands of genes for investigating the molecular antitumor mechanism of thalidomide.
To investigate the genes expression profiles of multiple myeloma cell line RPMI8226 treated with thalidomide, cDNA microarray were used to detect thousands of gene expression in a chip. Two cDNA probes were prepared through reverse transcription from mRNA of RPMI8226 cells with or without thalidomide treatment. The probes were labled with Cy3 and Cy5 fluorescence dyes individually,
hybridized with cDNA microarray representing 1152 different human genes. Fluorescent intensity were scanned and screened by means of differential analysis between two gene expression profiles. After 72 hrs’ co-culture of RPMI8226 cells and thalidomide in 100μmol/L concentration, the expression of 18 genes were up-regulated and 4 genes were down-regulated. The up-regulated genes(GeneBank Accession) included: 1) protein synthesis-related genes:NM_004184(WARS), NM_ 003335(UBE1L); 2) immune-related protein:NM_001465(FYB), NM_004341 (CAD), NM_002388(MCM3); 3) matabolism relatedgenes: BC008861, NM_001640(APEH), NM_020040(TUBB4Q), NM_001033(RRM1), NM_ 001976(ENO3), NM_003330 (TXNRD1); 4) cell signals and transducing proteins: NM_005167(ARHC), NM_001465(FYB); 5) other genes: NM_ 017432(PTOV1), NM_003564 (TAGLN2), NM_005053(RAD23A), NM_ 001033(RRM1), AK025983, NM_015685 (CLONE24904), NM_033158 (HYAL2). The down-regulated genes includes: 1) protein synthesis-related genes: NM_000994(RPL32); 2) immune-related proteins: NM_001551 (IGBP1); 3) other genes: NM_002983(SCYA3), NM_002421(MMP1).
These genes were involved in preotein synthesis and degradation, cell signal transduction, cytoskeletal movement immune cell matabolism and regulation of anti-oncogene. WARS gene encoding tryptophanyl-tRNA synthetase was up-regulated by thalidomide, while MMP1 gene encoding matrix metalloprotein 1 was down-regulated. They may be related to the inhibition of angiogenesis caused by thalidomide. SCYA3 gene encoding macrophage inflammatory protein-1alpha was down-regulated by thalidomide, as well as IGBP1 gene which encoding immunoglobulin binding protein 1. They may play a role in the inhibition of cell proliferation caused by thalidomide. TUBB4Q gene encoding tubulinβ4, UBE1L gene encoding ubiquitin- activating enzyme E1-like protein and TXNRD1 gene encoding thioredoxin reductase 1 were up-regulated by thalidomide. They may involve in apoptosis of RPMI8226 cells induced by thalidomide. FYB gene encoding Fyn-binding protein was up regulated by thalidomide. The elevated expression of this gene may play a role in the killing of RPMI8226 cells by thalidomide.
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