High-throughput screen identifies disulfiram as a potential therapeutic for triple-negative breast cancer cells: Interaction with IQ motif-containing factors

Triple-negative breast cancer (TNBC) represents an aggressive subtype, for which radiation and chemotherapy are the only options. Here we describe the identification of disulfiram, an FDA-approved drug used to treat alcoholism, as well as the related compound thiram, as the most potent growth inhibitors following high-throughput screens of 3185 compounds against multiple TNBC cell lines. The average IC₅₀ for disulfiram was ~300 nM. Drug affinity responsive target stability (DARTS) analysis identified IQ motif-containing factors IQGAP1 and MYH9 as direct binding targets of disulfiram. Indeed, knockdown of these factors reduced, though did not completely abolish, cell growth. Combination treatment with 4 different drugs commonly used to treat TNBC revealed that disulfiram synergizes most effectively with doxorubicin to inhibit cell growth of TNBC cells. Disulfiram and doxorubicin cooperated to induce cell death as well as cellular senescence, and targeted the ESA⁺/CD24^-/low/CD44⁺ cancer stem cell population. Our results suggest that disulfiram may be repurposed to treat TNBC in combination with doxorubicin.     

Keratin 5-Cre-driven excision of nonmuscle myosin IIA in early embryo trophectoderm leads to placenta defects and embryonic lethality

In studies initially focused on roles of nonmuscle myosin IIA (NMIIA) in the developing mouse epidermis, we have discovered that a previously described cytokeratin 5 (K5)-Cre gene construct is expressed in early embryo development. Mice carrying floxed alleles of the nonmuscle myosin II heavy chain gene (NMHC IIA^flox/flox) were crossed with the K5-Cre line. The progeny of newborn pups did not show a Mendelian genotype distribution, suggesting embryonic lethality. Analysis of post-implantation conceptuses from embryonic day (E)9.5 to E13.5 revealed poorly developed embryos and defective placentas, with significantly reduced labyrinth surface area and blood vessel vascularization. These results suggested the novel possibility that the bovine K5 promoter-driven Cre-recombinase was active early in trophoblast-lineage cells that give rise to the placenta. To test this possibility, K5-Cre transgenic mice were crossed with the mT/mG reporter mouse in which activation of GFP expression indicates Cre transgene expression. We observed activation of K5-Cre-driven GFP expression in the ectoplacental cone, in the extraembryonic ectoderm, and in trophoblast giant cells in the E6.5 embryo. In addition, we observed GFP expression at E11.5 to E13.5 in both the labyrinth of the placenta and the yolk sac. NMIIA expression was detected in these same cell types in normal embryos, as well as in E13.5 yolk sac and labyrinth. These findings taken together suggest that NMHC IIA may play critical roles in the early trophoblast-derived ectoplacental cone and extraembryonic ectoderm, as well as in the yolk sac and labyrinth tissues that form later. Our findings are consistent with phenotypes of constitutive NMIIA knockout mice made earlier, that displayed labyrinth and yolk sac-specific defects, but our findings extend those observations by suggesting possible NMIIA roles in trophoblast lineages as well. These results furthermore demonstrate that K5-Cre gene constructs, previously reported to be activated starting at approximately E12.5 in the forming epidermis, may be widely useful as drivers for activation of cre/lox based gene excision in early embryo extraembronic trophoblast tissues as well.     

MYH9 基因多态性与肾脏疾病关系研究进展

非肌性肌球蛋白重链9基因,编码非肌性肌球蛋白重链ⅡA,既往研究其与May-Hegglin异常(May-Hegglin anomaly,MHA)、Fechtner综合征(Fechtner syndrome,FTNS)、Sebastian综合征(Sebastian syndrome,SBS)、Epstein综合征(Epstein syndrome,EPS)和Alport样综合征相关。2008年首次用混合连锁不平衡绘图(MALD)方法证实其与非糖尿病终末期肾病及局灶节段性肾小球硬化症相关,后陆续有该基因与高血压肾病、C1q肾病等的相关报道。本文综合国外该基因与肾脏病的相关研究,对其与肾脏病的关系研究进展做一概括,对今后的研究起一定的帮助作用。     

Down-regulation of MYH10 driven by chromosome 17p13.1 deletion promotes hepatocellular carcinoma metastasis through activation of the EGFR pathway

Somatic copy number alterations (CNAs) are a genomic hallmark of cancers. Among them, the chromosome 17p13.1 deletions are recurrent in hepatocellular carcinoma (HCC). Here, utilizing an integrative omics analysis, we screened out a novel tumour suppressor gene within 17p13.1, myosin heavy chain 10 (MYH10). We observed frequent deletions (~38%) and significant down-regulation of MYH10 in primary HCC tissues. Deletion or decreased expression of MYH10 was a potential indicator of poor outcomes in HCC patients. Knockdown of MYH10 significantly promotes HCC cell migration and invasion in vitro, and overexpression of MYH10 exhibits opposite effects. Further, inhibition of MYH10 markedly potentiates HCC metastasis in vivo. We preliminarily elucidated the mechanism by which loss of MYH10 promotes HCC metastasis by facilitating EGFR pathway activation. In conclusion, our study suggests that MYH10, a candidate target gene for 17p13 deletion, acts as a tumour suppressor and may serve as a potential prognostic indicator for HCC patients.     

MYH9在肾脏纤维化中表达及作用研究

目的:探讨MYH9(非肌性肌球蛋白重链9)在肾脏纤维化过程中的表达变化以及这种异常表达在疾病发展过程所发挥的作用。方法:通过免疫组化染色,Western blot以及实时PCR检测了MYH9在肾脏纤维化组织中表达水平的变化。同时在慢病毒介导下构建稳定过表达MYH9的肾脏纤维化HK-2细胞,并通过MTT实验、流式细胞仪检测MYH9对HK-2细胞增殖和细胞周期的影响。结果:在小鼠肾脏纤维化组织中MYH9表达水平明显高于正常小鼠肾脏组织(P0.05)。上调MYH9对肾脏纤维化细胞HK-2的增殖水平和细胞周期都呈现出明显的促进(P0.05)。结论:MYH9在肾脏纤维化过程中发挥了重要的促进作用,针对MYH9为靶点的研究为肾脏纤维化的治疗提供新的思路。     

Rat MYH,a glycosylase for repair of oxidatively damaged DNA,has brain-specific isoforms that localize to neuronal mitochondria

Mitochondrial genomes are exposed to a heavy load of reactive oxygen species (ROS) that damage DNA. Since in neurons, mitochondrial DNA integrity must be maintained over the entire mammalian life span, neuronal mitochondria most likely repair oxidatively damaged DNA. We show that the Escherichia coli MutY DNA glycosylase homolog (MYH) in rat (rMYH) involved in repair of oxidative damage is abundantly expressed in the rat brain, with isoforms that are exclusive to brain tissue. Confocal microscopy and western analyses reveal localization of rMYH in neuronal mitochondria. To assess involvement of MYH in the neuronal response to oxidative DNA damage, we used a rat model of respiratory hypoxia, in which acutely reduced blood oxygenation leads to generation of superoxide, and formation and subsequent removal of 8-hydroxy-2'-deoxyguanosine (8OHdG). Removal of 8OHdG is accompanied by a spatial increase in rMYH immunoreactivity in the brain and an increase in levels of one of the three mitochondrial MYH isoforms, suggesting that inducible and non-inducible MYH isoforms exist in the brain. The mitochondrial localization of oxidative DNA damage repair enzymes in neurons may represent a specialized neuronal mechanism that safeguards mitochondrial genomes in the face of routine and accidental exposures to heavy loads of injurious ROS.