title: The rGel/BLyS fusion toxin inhibits STAT3 signaling via down-regulation of interleukin-6 receptor in diffuse large B-cell lymphoma.
abstract: Aberrant signal transducer and activator of transcription (STAT)3 signaling participates in the development and progress of human cancers. We previously generated a highly cytotoxic fusion toxin designated rGel/BLyS for receptor-mediated delivery of the rGel toxin to malignant B-cells. In this study, we examined this fusion toxin for its ability to impact STAT3 signaling in diffuse large B-cell lymphoma (DLBCL). The activated B cell-like DLBCL lines were found to express higher levels of interleukin-6 receptor (IL-6R) and STAT3 than did the germinal center B cell-like DLBCL lines. Treatment of DLBCL cells with rGel/BLyS resulted in down-regulation of IL-6R and inhibited STAT3 phosphorylation, STAT3-DNA binding activity, and IL-6-inducible STAT3 reporter gene activity. In agreement with these results, we additionally found that rGel/BLyS down-regulated levels of several STAT3 targets (c-Myc, p21, Mcl-1, and Bcl-x(L)) and p-SYK, a positive regulator of STAT3. Inhibition of IL-6R-mediated STAT3 signaling by rGel/BLyS led to growth inhibition, triggered accumulation of cells in the sub-G(1) phase of the cell cycle, and induced apoptosis. Our results indicate that rGel/BLyS is an excellent candidate for the treatment of aggressive DLBCL which is resistant to conventional chemotherapeutic regimens and STAT3 signaling pathway may be an attractive therapeutic target for non-Hodgkin's lymphoma.
authors.affiliation: Department of Experimental Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, USA.
authors.forename: Mi-Ae
authors.initials: MA
authors.lastname: Lyu
authors.forename: Bokyung
authors.initials: B
authors.lastname: Sung
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Cheung
authors.forename: John W
authors.initials: JW
authors.lastname: Marks
authors.forename: Bharat B
authors.initials: BB
authors.lastname: Aggarwal
authors.forename: Ricardo C T
authors.initials: RC
authors.lastname: Aguiar
authors.forename: Michael G
authors.initials: MG
authors.lastname: Rosenblum
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D053264:B-Cell Activating Factor / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004247:DNA / Q000378:metabolism; D015536:Down-Regulation; D016193:G1 Phase / Q000187:drug effects; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D016403:Lymphoma, Large B-Cell, Diffuse / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019947:Receptors, Interleukin-6 / Q000037:antagonists & inhibitors*; D011993:Recombinant Fusion Proteins / Q000494:pharmacology*; D054789:Ribosome Inactivating Proteins, Type 1 / Q000494:pharmacology*; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D000072377:Syk Kinase
chemical_list: D053264:B-Cell Activating Factor; D047908:Intracellular Signaling Peptides and Proteins; D019947:Receptors, Interleukin-6; D011993:Recombinant Fusion Proteins; D054789:Ribosome Inactivating Proteins, Type 1; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C025674:GEL protein, Gelonium multiflorum; D004247:DNA; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; D051057:Proto-Oncogene Proteins c-akt