No abstract

Mutations or aberrant upregulation of EZH2 occur frequently in human cancers, yet clinical benefits of EZH2 inhibitor (EZH2i) remain unsatisfactory and limited to certain hematological malignancies. We profile global posttranslational histone modification changes across a large panel of cancer cell lines with various sensitivities to EZH2i. We report here oncogenic transcriptional reprogramming mediated by MLL1's interaction with the p300/CBP complex, which directs H3K27me loss to reciprocal H3K27ac gain and restricts EZH2i response. Concurrent inhibition of H3K27me and H3K27ac results in transcriptional repression and MAPK pathway dependency in cancer subsets. In preclinical models encompassing a broad spectrum of EZH2-aberrant solid tumors, a combination of EZH2 and BRD4 inhibitors, or a triple-combination including MAPK inhibition display robust efficacy with very tolerable toxicity. Our results suggest an attractive precision treatment strategy for EZH2-aberrant tumors on the basis of tumor-intrinsic MLL1 expression and concurrent inhibition of epigenetic crosstalk and feedback MAPK activation.

Modifying the genomes of many organisms is becoming as easy as manipulating DNA in test tubes, which is made possible by two recently developed techniques based on either the customizable DNA binding protein, TALEN, or the CRISPR/Cas9 system. Here, we describe a series of efficient applications derived from these two technologies, in combination with various homologous donor DNA plasmids, to manipulate the Drosophila genome: (1) to precisely generate genomic deletions; (2) to make genomic replacement of a DNA fragment at single nucleotide resolution; and (3) to generate precise insertions to tag target proteins for tracing their endogenous expressions. For more convenient genomic manipulations, we established an easy-to-screen platform by knocking in a white marker through homologous recombination. Further, we provided a strategy to remove the unwanted duplications generated during the “ends-in” recombination process. Our results also indicate that TALEN and CRISPR/Cas9 had comparable efficiency in mediating genomic modifications through HDR (homology-directed repair); either TALEN or the CRISPR/Cas9 system could efficiently mediate in vivo replacement of DNA fragments of up to 5 kb in Drosophila, providing an ideal genetic tool for functional annotations of the Drosophila genome.

Miscarriage is the spontaneous loss of an embryo or fetus before the 20th week of pregnancy. Most miscarriages occur before the end of the first trimester (<13 weeks). Although many risk factors relate to this occurrence, genetic factors play the most important role. Chromosomal abnormalities, including both numerical and structural anomalies, underlie the majority of miscarriages. In this study, we employed a comprehensive approach using cytogenetic karyotyping, polymerase chain reaction (PCR)-based genotyping, and microarray-based comparative genomic hybridization (arrayCGH) in combination to analyze chromosomal profiles of 115 first-trimester miscarriages of Chinese women. Seventy cases (61%) were found to have chromosomal anomalies, of which 90% were numerical and 10% were structural. Cytogenetic karyotyping identified 78.6% (55/70), PCR assays 2.9% (2 triploids), and arrayCGH 18.6% (13/70) of the anomalies. In this study, a microdeletion of 108 kb and four microduplications sizing from 300 to 1460 kb were observed. An advantage of using this combination approach is that microsatellite genotyping and arrayCGH can be accomplished in spite of culture failure and maternal cell contamination. In addition, arrayCGH can detect submicroscopic chromosomal anomalies and gene dosage alterations.

The strategy of molecularly precise self-assembly of theranostic nanoprobes within a single-molecular framework is used to avoid batch-to-batch variability, and concurrently achieving real-time tracking of the in vivo behaviour of prodrugs for the first time.

G9a, a H3K9 methyltransferase, shows elevated expression in many types of human cancers, particularly breast cancer. However, the tumorigenic mechanism of G9a is still far from clear. Here we report that G9a exerts its oncogenic function in breast cancer by repressing hephaestin and destruction cellular iron homeostasis. In the case of pharmacological inhibition or short hairpin RNA interference-mediated suppression of G9a, the expression and activity of hephaestin increases, leading to the observed decrease of intracellular labile iron content and the disturbance of breast cancer cell growth in vitro and in vivo. We also provide evidence that G9a interacts with HDAC1 and YY1 to form a multi-molecular complex that contributes to hephaestin silencing. Furthermore, high G9a expression and low hephaestin expression correlate with poor survival of breast cancer are investigated. All these suggest a G9a-dependent epigenetic program in the control of iron homeostasis and tumor growth in breast cancer.

Use of kinase inhibitors in cancer therapy leads invariably to acquired resistance stemming from kinase reprogramming.

Background: Non-small cell lung cancer (NSCLC) patients with activating EGFR mutations initially respond to first-generation EGFR inhibitors; however, the efficacy of these drugs is limited by acquired resistance driven by the EGFR T790M mutation. The discovery of third-generation EGFR inhibitors overcoming EGFR T790M and their new resistance mechanisms have attracted much attention. Methods: We examined the antitumor activities and potential resistance mechanism of a novel EGFR thirdgeneration inhibitor in vitro and in vivo using ELISA, SRB assay, immunoblotting, flow cytometric analysis, kinase array, qRT-PCR and tumor xenograft models. The clinical effect on a patient was evaluated by computed tomography scan. Results: We identified compound ASK120067 as a novel inhibitor of EGFR T790M , with selectivity over EGFR WT. ASK120067 exhibited potent anti-proliferation activity in tumor cells harboring EGFR T790M (NCI-H1975) and sensitizing mutations (PC-9 and HCC827) while showed moderate or weak inhibition in cells expressing EGFR WT. Oral administration of ASK120067 induced tumor regression in NSCLC xenograft models and in a PDX model harboring EGFR T790M. The treatment of one patient with advanced EGFR T790M-positive NSCLC was described as proof of principle. Moreover, we found that hyperphosphorylation of Ack1 and the subsequent activation of antiapoptotic signaling via the AKT pathway contributed to ASK120067 resistance. Concomitant targeting of EGFR and Ack1 effectively overrode the acquired resistance of ASK120067 both in vitro and in vivo. Conclusions: Our results idenfity ASK120067 as a promising third-generation EGFR inhibitor and reveal for the first time that Ack1 activation as a novel resistance mechanism to EGFR inhibitors that guide to potential combination strategy.