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Journal of Investigative Medicine:
doi: 10.231/JIM.0b013e318237eb55
Original Articles

Protein Kinase C-Beta Inhibition Induces Apoptosis and Inhibits Cell Cycle Progression in Acquired Immunodeficiency Syndrome–Related Non-Hodgkin Lymphoma Cells

Saba, Nakhle S. MD*†; Levy, Laura S. PhD†‡

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Abstract

Introduction: Acquired immunodeficiency syndrome (AIDS)-related non-Hodgkin lymphoma (NHL) constitutes an aggressive variety of lymphomas characterized by increased extranodal involvement, relapse rate, and resistance to chemotherapy. Protein kinase C-beta (PKCβ) targeting showed promising results in preclinical and clinical studies involving a wide variety of cancers, but studies describing the role of PKCβ in AIDS-NHL are primitive if not lacking.

Methods: In the present study, 3 AIDS-NHL cell lines were examined: 2F7 (AIDS–Burkitt lymphoma), BCBL-1 (AIDS–primary effusion lymphoma), and UMCL01-101 (AIDS–diffuse large B-cell lymphoma).

Results: Immunoblot analysis demonstrated expression of PKCβ1 and PKCβ2 in 2F7 and UMCL01-101 cells, and PKCβ1 alone in BCBL-1 cells. The viability of 2F7 and BCBL-1 cells decreased significantly in the presence of PKCβ-selective inhibitor at half-maximal inhibitory concentration of 14 and 15 μmol/L, respectively, as measured by tetrazolium dye reduction assay. In contrast, UMCL01-101 cells were relatively resistant. As determined using flow cytometric deoxynucleotidyl transferase dUTP nick-end labeling assay with propidium iodide staining, the responsiveness of sensitive cells was associated with apoptotic induction and cell cycle inhibition. Protein kinase C-beta–selective inhibition was observed not to affect AKT phosphorylation but to induce a rapid and sustained reduction in the phosphorylation of glycogen synthase kinase-3 beta, ribosomal protein S6, and mammalian target of rapamycin in sensitive cell lines.

Conclusions: The results indicate that PKCβ plays an important role in AIDS-related NHL survival and suggest that PKCβ targeting should be considered in a broader spectrum of NHL. The observations in BCBL-1 were unexpected in the absence of PKCβ2 expression and implicate PKCβ1 as a regulator in those cells.

© 2012 American Federation for Medical Research

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