Inhibition of cancer-associated mutant isocitrate dehydrogenases: synthesis, structure-activity relationship, and selective antitumor activity.

Mutations of isocitrate dehydrogenase 1 (IDH1) are frequently found in certain cancers such as glioma. Different from the wild-type (WT) IDH1, the mutant enzymes catalyze the reduction of α-ketoglutaric acid to d-2-hydroxyglutaric acid (D2HG), leading to cancer initiation. Several 1-hydroxypyridin-2-one compounds were identified to be inhibitors of IDH1(R132H).

Oncogenic features of PHF8 histone demethylase in esophageal squamous cell carcinoma.

Esophageal cancer is the sixth leading cause of cancer-related deaths worldwide. It has been reported that histone demethylases are involved in the carcinogenesis of certain types of tumors. Here, we studied the role of one of the histone lysine demethylases, plant homeodomain finger protein 8 (PHF8), in the carcinogenesis of esophageal squamous cell carcinoma (ESCC).

A novel application of furazolidone: anti-leukemic activity in acute myeloid leukemia.

Acute myeloid leukemia (AML) is the most common malignant myeloid disorder of progenitor cells in myeloid hematopoiesis and exemplifies a genetically heterogeneous disease. The patients with AML also show a heterogeneous response to therapy. Although all-trans retinoic acid (ATRA) has been successfully introduced to treat acute promyelocytic leukemia (APL), it is rather ineffective in non-APL AML.

The histone demethylase PHF8 governs retinoic acid response in acute promyelocytic leukemia.

While all-trans retinoic acid (ATRA) treatment in acute promyelocytic leukemia (APL) has been the paradigm of targeted therapy for oncogenic transcription factors, the underlying mechanisms remain largely unknown, and a significant number of patients still relapse and become ATRA resistant. We identified the histone demethylase PHF8 as a coactivator that is specifically recruited by RARα fusions to activate expression of their downstream targets upon ATRA treatment. Forced expression of PHF8 resensitizes ATRA-resistant APL cells, whereas its downregulation confers resistance.

The X-linked mental retardation gene PHF8 is a histone demethylase involved in neuronal differentiation.

Recent studies have identified mutations in PHF8, an X-linked gene encoding a JmjC domain-containing protein, as a causal factor for X-linked mental retardation (XLMR) and cleft lip/cleft palate. However, the underlying mechanism is unknown. Here we show that PHF8 is a histone demethylase and coactivator for retinoic acid receptor (RAR).

Leukemic transformation by the APL fusion protein PRKAR1A-RAR{alpha} critically depends on recruitment of RXR{alpha}.

PRKAR1A (R1A)-retinoic acid receptor-alpha (R1A-RARalpha) is the sixth RARalpha-containing fusion protein in acute promyelocytic leukemia (APL). Using the murine bone-marrow retroviral transduction/transformation assay, we showed that R1A-RARalpha fusion protein could transform bone-marrow progenitor/stem cells. In gel-shift assays, R1A-RARalpha was able to bind to a panel of retinoic acid response elements both as a homodimer and as a heterodimer with RXRalpha, and demonstrated distinct DNA-binding characteristics compared with wild-type RARalpha/RXRalpha or other X-RARalpha chimeric proteins.

Coiled-coil domain of PML is essential for the aberrant dynamics of PML-RARalpha, resulting in sequestration and decreased mobility of SMRT.

Promyelocytic leukemia-retinoic acid receptor alpha (PML-RARalpha) is the most frequent RARalpha fusion protein in acute promyelocytic leukemia (APL). Our previous study has demonstrated that, compared with RARalpha, PML-RARalpha had reduced intranuclear mobility accompanied with mislocalization. To understand the molecular basis for the altered dynamics of PML-RARalpha fusion protein, we performed FRAP analysis at a single cell level.

Stat3 isoforms, alpha and beta, demonstrate distinct intracellular dynamics with prolonged nuclear retention of Stat3beta mapping to its unique C-terminal end.

Two isoforms of Stat3 (signal transducer and activator of transcription 3) are expressed in cells, alpha (p92) and beta (p83), both derived from a single gene by alternative mRNA splicing. The 55-residue C-terminal transactivation domain of Stat3alpha is deleted in Stat3beta and replaced by seven unique C-terminal residues (CT7) whose function remains uncertain. We subcloned the open reading frames of Stat3alpha and Stat3beta into the C terminus of green fluorescent protein (GFP).

Aberrant chromatin remodeling by retinoic acid receptor alpha fusion proteins assessed at the single-cell level.

Acute promyelocytic leukemia (APL) is characterized by specific chromosomal translocations, which generate fusion proteins such as promyelocytic leukemia (PML)-retinoic acid receptor (RAR)alpha and promyelocytic leukemia zinc finger (PLZF)-RARalpha (X-RARalpha). In this study, we have applied lac operator array systems to study the effects of X-RARalpha versus wild-type RARalpha on large-scale chromatin structure. The targeting of these enhanced cyan fluorescent protein-lac repressor-tagged RARalpha-containing proteins to the gene-amplification chromosomal region by lac operator repeats led to local chromatin condensation, recruitment of nuclear receptor corepressor, and histone deacetylase complex.

Reduced intranuclear mobility of APL fusion proteins accompanies their mislocalization and results in sequestration and decreased mobility of retinoid X receptor alpha.

Acute promyelocytic leukemia (APL) cells contain one of five chimeric retinoic acid alpha-receptor (RAR alpha) genes (X-RAR alpha) created by chromosomal translocations or deletion; each generates a fusion protein thought to transcriptionally repress RAR alpha target genes and block myeloid differentiation by an incompletely understood mechanism. To gain spatiotemporal insight into these oncogenic processes, we employed fluorescence microscopy and fluorescence recovery after photobleaching (FRAP). Fluorescence microscopy demonstrated that the intracellular localization of each of the X-RAR alpha proteins was distinct from that of RAR alpha and established which portion(s) of each X-RAR alpha protein-X, RAR, or both-contributed to its altered localization.

Essential role for the dimerization domain of NuMA-RARalpha in its oncogenic activities and localization to NuMA sites within the nucleus.

Nuclear mitotic apparatus protein-retinoic acid receptor alpha (NuMA-RARalpha) is the fourth of five fusion proteins identified in acute promyelocytic leukemia (APL) patients. The molecular basis for its oncogenic activity has not been delineated. In gel-shift assays, NuMA-RARalpha bound to retinoic acid response elements (RAREs) both as a homodimer and as a heterodimer with RXRalpha.