The proteasome inhibitor bortezomib targets cell cycle and apoptosis and acts synergistically in a sequence-dependent way with chemotherapeutic agents in mantle cell lymphoma

Abstract Signature abnormalities in the cell cycle and apoptotic pathway have been identified in mantle cell lymphoma (MCL), affording the opportunity to develop targeted therapies. Here, we report on a novel class of kinase inhibitors, styryl sulfones, that differ from prior cell cycle inhibitors in that they are not related to purines or pyrimidines. We observed that two closely related compounds, ON013100 and ON01370, altered the growth and cell cycle status of MCL lines and potently inhibited the expression of several important molecules, including CDK4, p53, MDM2, cyclin D, and cyclin B. Using both TUNEL and PARP assays, we found that these compounds caused apoptosis in MCL cells. In addition, using molecular analyses, we observed the modulation of caspase-3 activity but not the expression of Bcl family molecules in these cells. Next, we investigated the cytotoxicity of the MCL lines upon treatment with styryl sulfone compounds in combination with other currently used chemotherapeutic agents, such as doxorubicin (DOX) or vincristine (VCR). We found that the combination of DOX plus styryl sulfone or VCR plus styryl sulfone increased cytotoxicity by one log scale, compared with the single styryl sulfone compound. Thus styryl sulfones alone, or in combination with chemotherapeutic agents, present attractive opportunities for new drug development in MCL.

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Cell Cycle Dysregulation Represents an Early Effect of the Proteasome Inhibitor Bortezomib in Mantle Cell Lymphoma.

Blood ◽

10.1182/blood.v104.11.2287.2287 ◽

2004 ◽

Vol 104 (11) ◽

pp. 2287-2287 ◽

Cited By ~ 2

Author(s):

Grit Hutter ◽

Yvonne Zimmermann ◽

Malte Rieken ◽

Marc Weinkauf ◽

Oliver Weigert ◽

...

Keyword(s):

Cell Cycle ◽

Protein Expression ◽

Cyclin D1 ◽

Mantle Cell Lymphoma ◽

Cell Lines ◽

Proteasome Inhibitor ◽

Cell Lymphoma ◽

Genetic Alterations ◽

Cell Cycle Regulators ◽

Mantle Cell

Abstract Mantle cell lymphoma (MCL) is a distinct subtype of malignant lymphoma with an especially poor clinical outcome, a median survival time of 3 years and virtually no long-term survivors. On the molecular level, MCL is characterized by the chromosomal translocation t(11;14)(q13;q32) resulting in the constitutive overexpression of cyclin D1. However, additional genetic alterations of cell cycle regulators, e.g. deletions of the INK4A gene cluster, are detectable in the majority of cases. In various phase II studies the proteasome inhibitor bortezomib (Velcade) has demonstrated a high clinical efficacy with up to 60% remission rates in relapsed MCL. Additionally, in a previous in vitro study, the inhibitor induced a downregulation of cyclin D1 expression and a concomitant G(1) cell cycle arrest. However, little is known which molecules represent the critical targets of proteosome inhibition and how different regulators of cell cycle and apoptosis (inhibitors of CDK/INK4: p15INK4A, p16INK4B -and p14ARF and other kinase inhibitor proteins/KIP: 21CIP1, p27KIP1 and p57KIP2) are affected. 4 MCL cell lines (HBL2, GRANTA 519, Jeko-1, NCEB-1) and 2 hematological control cell lines (Jurkat, Karpas 422) were exposed to bortezomib at the minimal cytotoxic concentration (25 nmol) which corresponds to clinically achieved drug levels and results in a significant cytolysis after 48 – 72 hours. Real-time RT-PCR and protein expression levels of various CDK inhibitors (INK4s, KIPs) and cyclin D1 were determined a 0, 4, 8 and 12 hours after treatment with bortezomib. In addition, RNA- and protein expression data were compared to functional cell cycle phase (FACS) and cell apoptosis. Prelimenary data indicate that downregulation of cyclin D1 RNA expression after 12 and 24h of treatment represents a rather late event whereas alterations of other cell cycle regulators (like p21CIP1) were detected siginificantly earlier in all four MCL cell lines. Thus, expression of cell cycle regulators may indicate early events of proteasome inhibition. A comparative analysis of the cell cycle regulation network is currently being performed and will be presented at the conference.

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