ABSTRACT
PURPOSE: Primary effusion lymphoma (PEL) is an aggressive subtype of non-Hodgkin lymphoma that shows malignant effusion most commonly seen in advanced AIDS patients. In this study, we clarified the potential role of VEGF and IL-6 in PEL fluid retention and evaluated the efficacy of humanized anti-VEGF monoclonal antibody (mAb), bevacizumab, and humanized anti-IL-6 receptor mAb, tocilizumab, against PEL. METHODS: The production of VEGF and IL-6, and the expression of IL-6Rα in PEL cell lines were examined. The antiproliferative effect of bevacizumab and tocilizumab on PEL cells was evaluated in vitro. The effect of tocilizumab on VEGF was also examined. An intraperitoneal xenograft mouse model was used for in vivo efficacy. RESULTS: Although we found the production of VEGF and IL-6, and the expression of IL-6Rα in PEL cell lines, bevacizumab and tocilizumab did not inhibit the proliferation of PEL cells in vitro. Tocilizumab decreased VEGF mRNA and VEGF production by inhibiting Stat3 phosphorylation and Stat3 binding to VEGF promoter. In a PEL xenograft mouse model that showed profuse ascites, bevacizumab suppressed ascites formation completely, indicating the critical role of VEGF for PEL fluid retention. Tocilizumab also significantly inhibited ascites formation in vivo. Moreover, these mAbs improved the overall survival of treated mice. CONCLUSIONS: IL-6-VEGF axis contributed to fluid retention, and bevacizumab and tocilizumab could be effective molecular targeting therapies for PEL.
Subject(s)
Apoptosis/drug effects , Cell Proliferation/drug effects , Interleukin-6/antagonists & inhibitors , Lymphoma, Primary Effusion/pathology , Lymphoma, Primary Effusion/prevention & control , Vascular Endothelial Growth Factor A/antagonists & inhibitors , Animals , Antineoplastic Agents/pharmacology , Blotting, Western , Chromatin Immunoprecipitation , Enzyme-Linked Immunosorbent Assay , Flow Cytometry , Humans , Immunoenzyme Techniques , Interleukin-6/genetics , Interleukin-6/metabolism , Lymphoma, Primary Effusion/metabolism , Male , Mice , Mice, Inbred NOD , Phosphorylation/drug effects , RNA, Messenger/genetics , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , STAT3 Transcription Factor/antagonists & inhibitors , STAT3 Transcription Factor/genetics , STAT3 Transcription Factor/metabolism , Tumor Cells, Cultured , Vascular Endothelial Growth Factor A/genetics , Vascular Endothelial Growth Factor A/metabolism , Xenograft Model Antitumor AssaysABSTRACT
Primary effusion lymphoma (PEL) is an aggressive subtype of non-Hodgkin lymphoma characterized by short survival with current therapies, emphasizing the urgent need to develop new therapeutic approaches. Brentuximab vedotin (SGN-35) is an anti-CD30 monoclonal antibody (cAC10) conjugated by a protease-cleavable linker to a microtubule-disrupting agent, monomethyl auristatin E. Brentuximab vedotin is an effective treatment of relapsed CD30-expressing Classical Hodgkin and systemic anaplastic large cell lymphomas. Herein, we demonstrated that PEL cell lines and primary tumors express CD30 and thus may serve as potential targets for brentuximab vedotin therapy. In vitro treatment with brentuximab vedotin decreased cell proliferation, induced cell cycle arrest, and triggered apoptosis of PEL cell lines. Furthermore, in vivo brentuximab vedotin promoted tumor regression and prolonged survival of mice bearing previously reported UM-PEL-1 tumors as well as UM-PEL-3 tumors derived from a newly established and characterized Kaposi's sarcoma-associated herpesvirus- and Epstein-Barr virus-positive PEL cell line. Overall, our results demonstrate for the first time that brentuximab vedotin may serve as an effective therapy for PEL and provide strong preclinical indications for evaluation of brentuximab vedotin in clinical studies of PEL patients.
Subject(s)
Apoptosis/drug effects , Cell Cycle/drug effects , Cell Proliferation/drug effects , Immunoconjugates/pharmacology , Ki-1 Antigen/immunology , Lymphoma, Primary Effusion/pathology , Animals , Blotting, Western , Brentuximab Vedotin , Flow Cytometry , Humans , Lymphoma, Primary Effusion/immunology , Lymphoma, Primary Effusion/prevention & control , Mice , Mice, Inbred NOD , Mice, SCID , RNA, Messenger/genetics , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , Tumor Cells, CulturedABSTRACT
Primary effusion lymphoma (PEL) is a refractory malignancy caused by human herpes virus 8 (HHV-8) in immunocompromised individuals. The tumor cells of PEL are characterized by constitutive NF-kappaB activation. Dehydroxymethylepoxyquinomicin (DHMEQ) is a new NF-kappaB inhibitor and is effective on various tumor cells with constitutively activated NF-kappaB. Thus, in search for a new therapeutic modality of PEL, we examined the effect of DHMEQ on PEL cells. We confirmed constitutive activation of NF-kappaB with subcomponents of p50 and p65 in PEL cell lines. DHMEQ quickly and transiently abrogated NF-kappaB activation and reduced the cell viability in dose- and time-dependent manners, inducing apoptosis through activation of both mitochondrial and membrane pathways. Array analysis revealed that DHMEQ down-regulated expression levels of NF-kappaB target genes, such as interleukin-6 (IL6), Myc, chemokine (C-C motif) receptor 5 (CCR5) and NF-kappaB1, whereas it up-regulated expression levels of some genes involved in apoptosis, and cell cycle arrest. DHMEQ did not reactivate HHV-8 lytic genes, indicating that NF-kappaB inhibition by DHMEQ did not induce virus replication. DHEMQ rescued CB-17 SCID mice xenografted with PEL cells, reducing the gross appearance of effusion. Thus, DHMEQ transiently abrogated the NF-kappaB activation, irreversibly triggering the apoptosis cascade without HHV-8 reactivation. In addition, DHMEQ could rescue the PEL-xenograft mice. Therefore, we suggest DHMEQ as a promising candidate for molecular target therapy of the PEL.
