The Regulation And Mechanisms Of Transcription Factor NF-?B On Adhesion Molecule VLA-4 Transcription

Multiple myeloma(MM)is a malignant plasma cell disease of the bone marrow that is an incurable disease characterized by the accumulation of malignant plasma cells in the bone marrow.At present,MM has become a multi-drug resistant disease after a long period of clonal evolution.Drug resistance is the main reason for its relapse and incurability.Therefore,the study of its resistance mechanism becomes extremely important.The drug resistance of cancer cells is affected by its microenvironment.The transmission of intercellular information and intercellular interaction in microenvironment play an important role in cell survival and drug resistance.The intercellular interaction is mainly mediated by adhesion molecules.According to the literature,adhesion molecule VLA-4 has a certain role in the drug resistance of extracellular matrix-regulated myeloma cells.In addition,we also found that the transcription factor NF-?B plays a decisive role in the drug resistance and pathological progression of myeloma.For VLA-4,it is an undiscovered NF-?B downstream molecule.We investigated the role of NF-?B in the regulation of VLA-4 gene expression.All possible NF-?B binding sites were identified by sequence analysis.According to the position of these sites in the upstream sequence,appropriate primers were designed to synthesize the ?4 subunit gene regulatory sequence and cloned into the reporter vector.Reporter assays have shown that these upstream sequences of the VLA-4? gene containing NF-?B binding sites have almost no effect on the expression of the luciferase as a reporter gene.Considering the possibility that introns contain regulatory sequences,eight possible NF-?B binding sequences in introns have been identified.Unfortunately,these sequences have no substantive significance for the expression level of luciferase.At the same time,we also performed deletion of the NF-?B potential binding site and found that the deleted plasmid did not significantly reduce its relative luciferase activity after transfection.During the course of the study,we found that the base of the VLA-4? upstream regulatory sequence-2328 in the genome of the U937 cell expressing VLA-4? is C,while the same position in the Hela cell that did not express VLA-4? is T.To explore whether this SNP has an effect on the expression of VLA-4,we cloned and sequenced the corresponding genomic sequence of a total of 8 cells and found that VLA-4? is expressed both in SNP-containing cells and in SNP-free cells.Therefore,SNP is not a major factor affecting the expression level of VLA-4.We also examined changes in VLA-4? transcriptional levels and their cell surface expression levels before and after activation of NF-?B by TNF-?,but no significant changes were found.Therefore,we conclude that NF-?B may not be the major regulator of VLA-4,or that its regulatory function is inhibited by negative regulators,or that its regulation functions only play the role under certain conditions.