Histone Deacetylase Activity Represses Gamma Interferon-Inducible HLA-DR Gene Expression following the Establishment of a DNase I-Hypersensitive Chromatin Conformation

Abstract

Expression of the retinoblastoma tumor suppressor protein (Rb) is required for gamma interferon (IFN-␥Major histocompatibility complex (MHC) class II molecules are heterodimeric cell surface glycoproteins comprised of both a heavy (alpha) chain and a light (beta) chain. MHC class II molecules (HLA-DR, -DP, and -DQ in humans) bind and display peptide antigens for recognition by CD4 ϩ T lymphocytes. Recognition of the MHC class II heterodimer-antigen complex by the T-cell receptor and the accessory protein CD4 of T lymphocytes leads to the generation of an immune response. MHC class II molecules play an important role in antitumor immunity (1-4, 11, 29, 42-44, 49). Specifically, transfection of tumor cells with syngeneic murine MHC class II genes immunizes mice against MHC class II-negative parental tumor cells (2). Vaccination of mice using this protocol also leads to eradication of an MHC class II-negative, basement membrane-invasive tumor (4). Also, tumor-specific antigens capable of eliciting HLA class II-restricted activation of tumorinfiltrating T lymphocytes have been identified (46,57,58).MHC class II expression is constitutively activated during development in professional antigen-presenting cells, such as B cells, dendritic cells, and macrophages; it is inducible by cytokines, most importantly, gamma interferon (IFN-␥), in nearly all other types of cells. MHC class II expression is regulated primarily at the level of transcription through promoter elements that are conserved among the MHC class II genes and the genes encoding accessory molecules such as the invariant chain, the MHC class II chaperone. The elements are, from 5Ј to 3Ј, S box, X1 box, X2 box, Y box, and TATA box. The transactivators RFX, X2BP (CREB), and NF-Y are required factors for MHC class II gene activation and bind the X1, X2, and Y boxes, respectively. Cooperative interactions between transactivators bound to the X and Y elements have been demonstrated to be essential for the establishment of promoter occupancy and the transcription of class II genes (60). In particular, binding of the Y box factor, NF-Y, has been demonstrated to be required for occupancy of the other promoter elements and for IFN-␥-inducible MHC class II gene expression (60). In addition to the promoter binding factors, the class II transactivator (CIITA) is a required coactivator that functions by interaction with and stabilization of the transcription factors previously assembled on MHC class II promoters (20,24,38,53,59,68).It has been shown that the retinoblastoma tumor suppressor protein (Rb) is also required for IFN-␥-inducible MHC class II gene expression (34,35,41,67). Several Rb-defective human tumor cell lines exhibit a loss of IFN-␥-inducible MHC class II gene expression that is rescued by the reexpression of func-* Corresponding author. Mailing address:

Rescue of Major Histocompatibility-DR Surface Expression in Retinoblastoma-Defective, Non-small Cell Lung Carcinoma Cells by the MS-275 Histone Deacetylase Inhibitor

“…Results indicated that MS-275 facilitated substantial induction of cell surface HLA-DR, when compared to normal skin fibroblasts, a positive control for the normal level of the HLA-DR IFN-g response. This result is consistent with results obtained with other HDAC inhibitors 8) and indicates that an HDAC inhibitor suitable for patient therapy can facilitate surface HLA-DR induction.…”

“…To further clarify the initial results, we determined whether the YY1 site, which tethers a YY1-HDAC complex to the HLA-DRA promoter, 8) was related to the MS-275 effect. We transfected an HLA-DRA promoter luciferase construct, termed pDRA, and pDRA lacking the YY1 site, termed pDRA YY1mut, into the H2009 cells.…”

“…8,9) The requirement of IFN-g appears to be variable, but at a minimum, the combination of IFN-g treatment and the above HDAC inhibitors has always led to the rescue of MHC class II surface expression.…”

“…[6][7][8] The histon deacetylase (HDAC) inhibitors, sodium butyrate and trichostatin A can induce MHC class II surface expression in tumor cells. 8,9) The requirement of IFN-g appears to be variable, but at a minimum, the combination of IFN-g treatment and the above HDAC inhibitors has always led to the rescue of MHC class II surface expression. 10) However, this process has never been reported for a class I specific HDAC inhibitor and in particular has never been reported for an HDAC inhibitor in clinical trials.…”

The histone deacetylase inhibitor trichostatin A induces GADD45γ expression via Oct and NF-Y binding sites

“…A possible mechanism is that TSA alters the DNA-binding ability of Oct-1 or NF-Y. In fact, it has been reported that the binding activity of Oct-1 to the HLA-DRA promoter is greatly reduced by TSA treatment (Osborne et al, 2001). However, EMSAs showed that TSA treatment did not change the affinity of nuclear factors for the NF-Y or Oct sites in the murine GADD45g promoter (unpublished observations).…”