Upregulation of the EGFR/MEK1/MAPK1/2 signaling axis as a mechanism of resistance to antiestrogen‑induced BimEL dependent apoptosis in ER breast cancer cells.

The epidermal growth factor receptor (EGFR) is commonly upregulated in multiple cancer types, including breast cancer. In the present study, evidence is provided in support of the premise that upregulation of the EGFR/MEK1/MAPK1/2 signaling axis during antiestrogen treatment facilitates the escape of breast cancer cells from BimEL‑dependent apoptosis, conferring resistance to therapy. This conclusion is based on the findings that ectopic BimEL cDNA overexpression and confocal imaging studies confirm the pro‑apoptotic role of BimEL in ERα expressing breast cancer cells and that upregulated EGFR/MEK1/MAPK1/2 signaling blocks BimEL pro‑apoptotic action in an antiestrogen‑resistant breast cancer cell model.

DNA methylation: superior or subordinate in the epigenetic hierarchy?

Epigenetic modifications are heritable changes in gene expression not encoded by the DNA sequence. In the past decade, great strides have been made in characterizing epigenetic changes during normal development and in disease states like cancer. However, the epigenetic landscape has grown increasingly complicated, encompassing DNA methylation, the histone code, noncoding RNA, and nucleosome positioning, along with DNA sequence.

Presentation of acquired peptide-MHC class II ligands by CD4+ regulatory T cells or helper cells differentially regulates antigen-specific CD4+ T cell response.

Activated T cells can acquire membrane molecules from APCs through a process termed trogocytosis. The functional consequence of this event has been a subject of debate. Focusing on transfer of peptide-MHC class II (MHC-II) complexes from APCs to CD4(+) T cells after activation, in this study we investigated the molecule acquisition potential of naturally occurring regulatory T cells (Tregs) and CD4(+) Th cells.

Blockade of programmed death-1 pathway rescues the effector function of tumor-infiltrating T cells and enhances the antitumor efficacy of lentivector immunization.

Despite intensive effort, the antitumor efficacy of tumor vaccines remains limited in treating established tumors regardless of the potent systemic tumor-specific immune response and the increases of tumor infiltration of T effector cells. In the current study, we demonstrated that although lentivector (lv) immunization markedly increased Ag-dependent tumor infiltration of CD8 and CD4 T cells and generated Ag-specific antitumor effect, it simultaneously increased the absolute number of myeloid-derived suppressor cells and regulatory T cells in the tumor lesions. In addition, lv immunization induced expression of programmed death-ligand 1 in the tumor lesions.

Pan-histone deacetylase inhibitor panobinostat depletes CXCR4 levels and signaling and exerts synergistic antimyeloid activity in combination with CXCR4 antagonists.

Stromal cell derived factor-1 (SDF-1 or CXCL12) and its receptor CXCR4 are involved in the directional homing to the bone marrow niches and in peripheral mobilization of normal and transformed hematopoietic stem and myeloid progenitor cells. Elevated CXCR4 expression confers poor prognosis, whereas inhibition of CXCR4 signaling overcomes stroma-mediated chemoresistance in acute myeloid leukemia (AML). Here, we demonstrate that treatment with the pan-histone deacetylase inhibitor panobinostat (PS) depleted the mRNA and protein levels of CXCR4 in the cultured and primary AML cells.

Integration of transcript expression, copy number and LOH analysis of infiltrating ductal carcinoma of the breast.

Background: A major challenge in the interpretation of genomic profiling data generated from breast cancer samples is the identification of driver genes as distinct from bystander genes which do not impact tumorigenesis. One way to assess the relative importance of alterations in the transcriptome profile is to combine parallel analyses that assess changes in the copy number alterations (CNAs). This integrated analysis permits the identification of genes with altered expression that map within specific chromosomal regions which demonstrate copy number alterations, providing a mechanistic approach to identify the 'driver genes'.

Heat shock protein 90 inhibition depletes TrkA levels and signaling in human acute leukemia cells.

Nerve growth factor (NGF) induces autophosphorylation and downstream progrowth and prosurvival signaling from the receptor tyrosine kinase TrkA. Overexpression or activating mutation of TrkA has been described in human acute myeloid leukemia cells. In the present study, we show the chaperone association of TrkA with heat shock protein 90 (hsp90) and the inhibitory effect of the hsp90 inhibitor, 17-DMAG, on TrkA levels and signaling in cultured and primary myeloid leukemia cells.

Normal colon epithelium: a dataset for the analysis of gene expression and alternative splicing events in colon disease.

Background: Studies using microarray analysis of colorectal cancer have been generally beleaguered by the lack of a normal cell population of the same lineage as the tumor cell. One of the main objectives of this study was to generate a reference gene expression data set for normal colonic epithelium which can be used in comparisons with diseased tissues, as well as to provide a dataset that could be used as a baseline for studies in alternative splicing.

Results: We present a dependable expression reference data set for non-neoplastic colonic epithelial cells.

Cotreatment with panobinostat and JAK2 inhibitor TG101209 attenuates JAK2V617F levels and signaling and exerts synergistic cytotoxic effects against human myeloproliferative neoplastic cells.

The mutant JAK2V617F tyrosine kinase (TK) is present in the majority of patients with BCR-ABL-negative myeloproliferative neoplasms (MPNs). JAK2V617F activates downstream signaling through the signal transducers and activators of transcription (STAT), RAS/mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3 (PI3)/AKT pathways, conferring proliferative and survival advantages in the MPN hematopoietic progenitor cells (HPCs). Treatment with the pan-histone deacetylase (HDAC) inhibitor panobinostat (PS) is known to inhibit the chaperone function of heat shock protein 90, as well as induce growth arrest and apoptosis of transformed HPCs.

Interpreting aCGH-defined karyotypic changes in gliomas using copy number status, loss of heterozygosity and allelic ratios.

We have used SNP mapping arrays to simultaneously record copy number changes, loss of heterozygosity and allele ratios (ploidy) in a series of 13 gliomas. This combined analysis has defined novel amplification events in this tumor type involving chr1:241544532-243005121 and chr18:54716681-54917277 which contain the AKT3 and ZNF532 genes, respectively. The high resolution of this analysis has also identified homozygous deletions involving chr17:25600031-26490848 and Chr19:53883612-55061878.

Investigational drugs targeting FLT3 for leukemia.

FMS-like tyrosine kinase-3 (FLT3) is a member of the class III membrane receptor tyrosine kinase family and is important in survival, proliferation and differentiation of hematopoietic cells. FLT3 is mutated in approximately 30% of acute myelogenous leukemia patients. These mutations involve internal tandem duplications in the juxtamembrane domain of the receptor and tyrosine kinase point mutations in the activation loop.

Combined epigenetic therapy with the histone methyltransferase EZH2 inhibitor 3-deazaneplanocin A and the histone deacetylase inhibitor panobinostat against human AML cells.

The polycomb repressive complex (PRC) 2 contains 3 core proteins, EZH2, SUZ12, and EED, in which the SET (suppressor of variegation-enhancer of zeste-trithorax) domain of EZH2 mediates the histone methyltransferase activity. This induces trimethylation of lysine 27 on histone H3, regulates the expression of HOX genes, and promotes proliferation and aggressiveness of neoplastic cells. In this study, we demonstrate that treatment with the S-adenosylhomocysteine hydrolase inhibitor 3-deazaneplanocin A (DZNep) depletes EZH2 levels, and inhibits trimethylation of lysine 27 on histone H3 in the cultured human acute myeloid leukemia (AML) HL-60 and OCI-AML3 cells and in primary AML cells.

Genetic fingerprinting of the development and progression of T-cell lymphoma in a murine model of atypical myeloproliferative disorder initiated by the ZNF198-fibroblast growth factor receptor-1 chimeric tyrosine kinase.

A mouse model of human ZNF198-fibroblast growth factor receptor-1 (FGFR1) stem cell leukemia lymphoma has been developed to investigate mechanisms of oncogenesis and progression. Using array-based comparative genomic hybridization, we followed disease progression after serial transplantation of ZNF198-FGFR1-transformed stem cells that give rise to a distinct myeloproliferative disorder and T-lymphoblastic leukemia. A consistent, frequently homozygous, chr14:53880459-55011545 deletion, containing the T-cell receptor alpha and delta genes, was identified in the bone marrow, spleen, and lymph nodes in all cases.

Application of oligonucleotides arrays for coincident comparative genomic hybridization, ploidy status and loss of heterozygosity studies in human cancers.

Many oligonucleotide arrays comprise of spotted short oligonucleotides from throughout the genome under study. Hybridization of tumor DNA samples to these arrays will provide copy number estimates at each reference point with varying degrees of accuracy. In addition to copy number changes, however, tumors often undergo loss of heterozygosity for specific regions of the genome without copy number changes and these genetic changes can only be identified using arrays that identify polymorphic alleles at each reference point.

Lentivector immunization stimulates potent CD8 T cell responses against melanoma self-antigen tyrosinase-related protein 1 and generates antitumor immunity in mice.

Recombinant lentivector immunization has been demonstrated to induce potent CD8 T cell responses in vivo. In this study, we investigated whether lentivector delivering a self/tumor Ag, tyrosinase related protein 1 (TRP1), could stimulate effective antitumor T cell responses. We found that immunization with lentivector expressing mutated TRP1 Ag elicited potent CD8 T cell responses against multiple TRP1 epitopes.

Cotreatment with BCL-2 antagonist sensitizes cutaneous T-cell lymphoma to lethal action of HDAC7-Nur77-based mechanism.

Pan-histone deacetylase inhibitors, for example, vorinostat and panobinostat (LBH589; Novartis Pharmaceuticals, East Hanover, NJ), have shown clinical efficacy against advanced cutaneous T-cell lymphoma (CTCL). However, the molecular basis of this activity remains unclear. HDAC7, a class IIA histone deacetylase (HDAC), is overexpressed in thymocytes, where it represses expression of the proapoptotic nuclear orphan receptor Nur77.

Role of acetylation and extracellular location of heat shock protein 90alpha in tumor cell invasion.

Heat shock protein (hsp) 90 is an ATP-dependent molecular chaperone that maintains the active conformation of client oncoproteins in cancer cells. An isoform, hsp90alpha, promotes extracellular maturation of matrix metalloproteinase (MMP)-2, involved in tumor invasion and metastasis. Knockdown of histone deacetylase (HDAC) 6, which deacetylates lysine residues in hsp90, induces reversible hyperacetylation and attenuates ATP binding and chaperone function of hsp90.

Hydroxamic acid analogue histone deacetylase inhibitors attenuate estrogen receptor-alpha levels and transcriptional activity: a result of hyperacetylation and inhibition of chaperone function of heat shock protein 90.

Purpose: The molecular chaperone heat shock protein (hsp)-90 maintains estrogen receptor (ER)-alpha in an active conformation, allowing it to bind 17beta-estradiol (E2) and transactivate genes, including progesterone receptor (PR)-beta and the class IIB histone deacetylase HDAC6. By inhibiting HDAC6, the hydroxamic acid analogue pan-HDAC inhibitors (HA-HDI; e.g.

Histone deacetylase inhibitors deplete enhancer of zeste 2 and associated polycomb repressive complex 2 proteins in human acute leukemia cells.

Human enhancer of zeste 2 (EZH2) protein belongs to the multiprotein polycomb repressive complex 2, which also includes suppressor of zeste 12 (SUZ12) and embryonic ectoderm development (EED). The polycomb repressive complex 2 complex possesses histone methyltransferase activity mediated by the Su(var)3-9, enhancer of zeste, and trithorax domain of EZH2, which methylates histone H3 on lysine (K)-27 (H3K27). In the present studies, we determined that treatment with the hydroxamate histone deacetylase inhibitor LBH589 or LAQ824 depleted the protein levels of EZH2, SUZ12, and EED in the cultured (K562, U937, and HL-60) and primary human acute leukemia cells.