A Noncanonical Flt3ITD/NF-kappa B Signaling Pathway Represses DAPK1 in Acute Myeloid Leukemia

作者：Shanmugam Rajasubramaniam; Gade Padmaja; Wilson Weekes Annique; Sayar Hamid; Suvannasankha Attaya; Goswami Chirayu; Li Lang; Gupta Sushil; Cardoso Angelo A; Al Baghdadi Tareq; Sargent Katie J; Cripe Larry D; Kalvakolanu Dhananjaya V; Boswell H Scott^*

来源：Clinical Cancer Research, 2012, 18(2): 360-369.

DOI：10.1158/1078-0432.CCR-10-3022

Purpose: Death-associated protein kinase 1 (DAPK1), a tumor suppressor, is a rate-limiting effector in an endoplasmic reticulum (ER) stress-dependent apoptotic pathway. Its expression is epigenetically suppressed in several tumors. A mechanistic basis for epigenetic/transcriptional repression of DAPK1 was investigated in certain forms of acute myeloid leukemia (AML) with poor prognosis, which lacked ER stress-induced apoptosis.
Experimental Design: Heterogeneous primary AMLs were screened to identify a subgroup with Flt3ITD in which repression of DAPK1, among NF-kappa B-and c-Jun-responsive genes, was studied. RNA interference knockdown studies were carried out in an Flt3ITD(+) cell line, MV-4-11, to establish genetic epistasis in the pathway Flt3ITD-TAK1-DAPK1 repression, and chromatin immunoprecipitations were carried out to identify proximate effector proteins, including TAK1-activated p52NF-kappa B, at the DAPK1 locus.
Results: AMLs characterized by normal karyotype with Flt3ITD were found to have 10- to 100-fold lower DAPK1 transcripts normalized to the expression of c-Jun, a transcriptional activator of DAPK1, as compared with a heterogeneous cytogenetic category. In addition, Meis1, a c-Jun-responsive adverse AML prognostic gene signature was measured as control. These Flt3ITD(+) AMLs overexpress relB, a transcriptional repressor, which forms active heterodimers with p52NF-kappa B. Chromatin immunoprecipitation assays identified p52NF-kappa B binding to the DAPK1 promoter together with histone deacetylase 2 (HDAC2) and HDAC6 in the Flt3ITD(+) human AML cell line MV-4-11. Knockdown of p52NF-kappa B or its upstream regulator, NF-kappa B-inducing kinase (NIK), de-repressed DAPK1. DAPK1-repressed primary Flt3ITD(+) AMLs had selective nuclear activation of p52NF-kB.
Conclusions: Flt3ITD promotes a noncanonical pathway via TAK1 and p52NF-kappa B to suppress DAPK1 in association with HDACs, which explains DAPK1 repression in Flt3ITD(+) AML. Clin Cancer Res; 18(2); 360-9.

• 出版日期2012-1-15