A microenvironment-mediated c-Myc/miR-548m/HDAC6 amplification loop in non-Hodgkin B cell lymphomas
Tint Lwin, Xiaohong Zhao, Fengdong Cheng, Xinwei Zhang, Andy Huang, Bijal Shah, Yizhuo Zhang, Lynn C. Moscinski, Yong Sung Choi, Alan P. Kozikowski, James E. Bradner, William S. Dalton, Eduardo Sotomayor, Jianguo Tao
Tint Lwin, Xiaohong Zhao, Fengdong Cheng, Xinwei Zhang, Andy Huang, Bijal Shah, Yizhuo Zhang, Lynn C. Moscinski, Yong Sung Choi, Alan P. Kozikowski, James E. Bradner, William S. Dalton, Eduardo Sotomayor, Jianguo Tao
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Research Article Oncology

A microenvironment-mediated c-Myc/miR-548m/HDAC6 amplification loop in non-Hodgkin B cell lymphomas

Abstract

A dynamic interaction occurs between the lymphoma cell and its microenvironment, with each profoundly influencing the behavior of the other. Here, using a clonogenic coculture growth system and a xenograft mouse model, we demonstrated that adhesion of mantle cell lymphoma (MCL) and other non-Hodgkin lymphoma cells to lymphoma stromal cells confers drug resistance, clonogenicity, and induction of histone deacetylase 6 (HDAC6). Furthermore, stroma triggered a c-Myc/miR-548m feed-forward loop, linking sustained c-Myc activation, miR-548m downregulation, and subsequent HDAC6 upregulation and stroma-mediated cell survival and lymphoma progression in lymphoma cell lines, primary MCL and other B cell lymphoma cell lines. Treatment with an HDAC6-selective inhibitor alone or in synergy with a c-Myc inhibitor enhanced cell death, abolished cell adhesion–mediated drug resistance, and suppressed clonogenicity and lymphoma growth ex vivo and in vivo. Together, these data suggest that the lymphoma-stroma interaction in the lymphoma microenvironment directly impacts the biology of lymphoma through genetic and epigenetic regulation, with HDAC6 and c-Myc as potential therapeutic targets.

Authors

Tint Lwin, Xiaohong Zhao, Fengdong Cheng, Xinwei Zhang, Andy Huang, Bijal Shah, Yizhuo Zhang, Lynn C. Moscinski, Yong Sung Choi, Alan P. Kozikowski, James E. Bradner, William S. Dalton, Eduardo Sotomayor, Jianguo Tao

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Figure 3

Cell adhesion–mediated downregulation of miR-548m and HDAC6 upregulation are required for CAM-DR.

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Cell adhesion–mediated downregulation of miR-548m and HDAC6 upregulation...
(A and B) Overexpression of miR-548m induces HDAC6 downregulation and lymphoma cell apoptosis and enhances mitoxantrone-induced cell apoptosis. Jeko-1 and SUDHL-4 cells transfected with pre–miR-548m or pre-miR control were treated with vehicle control or mitoxantrone (0.2 μM) for 24 hours with or without HK cell adhesion. *P < 0.05; **P > 0.05. (A) The relative level of HDAC6 protein was measured by quantitative densitometry and is indicated below each lane. (C) HDAC6 knockdown after 48 hours of transfection with HDAC6 shRNA constructs 1 or 2 or nonsilencing control. (D) Knockdown of HDAC6 induces cell apoptosis and enhances mitoxantrone-induced cell apoptosis with and without HK cell adhesion. Jeko-1 or SUDHL-4 cells transfected with HDAC6 shRNA-2 (shHDAC6) or control shRNA (shCtrl) were incubated for 48 hours and then treated with vehicle control or mitoxantrone (0.2 μM) for 24 hours. Apoptosis was analyzed by Annexin V. (E and F) Overexpression of HDAC6 inhibits mitoxantrone-induced lymphoma cell apoptosis in Jeko-1 cells in the presence of HK cell adhesion. Jeko-1 cells were transfected with pCDNA3 control (pLCtrl) or pCDNA3-HDAC6 (pLHDAC6) for 24 hours. Cells, collected and washed in suspension versus in adhesion with HK, were treated with mitoxantrone (0.2 μM) for 12 hours. (E) HDAC6 protein levels were then analyzed by Western blot and (F) apoptosis was analyzed by Annexin V. Data are representative of at least 3 independent experiments (mean ± SD).