Tamoxifen resistance in breast cancer is regulated by the EZH2–ERa–GREB1 transcriptional axis

Resistance to cancer treatment can be driven by epigenetic reprogramming of specific transcriptomes in favor of the refractory phenotypes. Here we discover that tamoxifen resistance in breast cancer is driven by a regulatory axis consisting of a master transcription factor, its cofactor, and an epigenetic regulator. The oncogenic histone methyltransferase EZH2 conferred tamoxifen resistance by silencing the expression of the estrogen receptor a (ERa) cofactor GREB1. In clinical specimens, induction of DNA methylation of a particular CpG-enriched region at the GREB1 promoter negatively correlated with GREB1 levels and cell sensitivity to endocrine agents. GREB1 also ensured proper cellular reactions to different ligands by recruiting distinct sets of ERa cofactors to cis-regulatory elements, which explains the contradictory biological effects of GREB1 on breast cancer cell growth in response to estrogen or antiestrogen. In refractory cells, EZH2-dependent repression of GREB1 triggered chromatin reallocation of ERa coregulators, converting the antiestrogen into an agonist. In clinical specimens from patients receiving adjuvant tamoxifen treatment, expression levels of EZH2 and GREB1 were correlated negatively, and taken together better predicted patient responses to endocrine therapy. Overall, our work suggests a new strategy to overcome endocrine resistance in metastatic breast cancer by targeting a particular epigenetic program. Significance: This study suggests a new strategy to overcome endocrine resistance in metastatic breast cancer by targeting a particular epigenetic program defined within.Fil: Wu, Yanming. University of Texas at San Antonio; Estados UnidosFil: Zhang, Zhao. University of Texas at San Antonio; Estados UnidosFil: Cenciarini, Mauro Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Proietti Anastasi, Cecilia Jazmín. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Amasino, Matías Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Hong, Tao. University of Texas at San Antonio; Estados Unidos. Central South University; ChinaFil: Yang, Mei. University of Texas at San Antonio; Estados UnidosFil: Liao, Yiji. University of Texas at San Antonio; Estados UnidosFil: Chiang, Huai-Chin. University of Texas at San Antonio; Estados Unidos. University Of Texas Health Science Center At San Antonio (ut Health San Antonio) ; University Of Texas At San Antonio;Fil: Kaklamani, Virginia G.. University Of Texas Health Science Center At San Antonio (ut Health San Antonio) ; University Of Texas At San Antonio;Fil: Jeselsohn, Rinath. Dana-farber Cancer Institute; Estados UnidosFil: Vadlamudi, Ratna K.. University Of Texas Health Science Center At San Antonio (ut Health San Antonio) ; University Of Texas At San Antonio;Fil: Huang, Tim Hui Ming. University Of Texas Health Science Center At San Antonio (ut Health San Antonio) ; University Of Texas At San Antonio;Fil: Li, Rong. University Of Texas Health Science Center At San Antonio (ut Health San Antonio) ; University Of Texas At San Antonio;Fil: De Angelis, Carmine. Baylor College Of Medicine; Estados UnidosFil: Fu, Xiaoyong. Baylor College Of Medicine; Estados UnidosFil: Elizalde, Patricia Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Schiff, Rachel. Baylor College Of Medicine; Estados UnidosFil: Brown, Myles. Dana farber Cancer Institute; Estados UnidosFil: Xu, Kexin. University Of Texas Health Science Center At San Antonio (ut Health San Antonio) ; University Of Texas At San Antonio

Dynamic Study on Chemisorbed Species of Oxygen over Gas-Solid Interfaces

【中文摘要】用自编的傅里叶变换红外（fT-Ir）动态谱批处理程序，在20-650℃对bE、Mg、CA、lA、CE、SM、TI、zr、V、nb、Cr、MO、W、Mn、fE、nI、Cu、zn和Sn等一系列金属氧化物上的氧化学吸附物种进行了原位动态三维谱学研究。就所观测到的超氧（O-2）和过氧（O2-2）物种随温度的变化情况以及甲烷氧化偶联催化反应中的活性氧物种进行了讨论。 【Abstract】The in-situ dynamic three-dimension FT-IR spectra of chemisorbed species of oxygen over metal oxides,such as MgO,CaO,La2O3,CeO2,Sm2O3,TiO2,ZrO2,V2O5,Nb2O5,Cr2O3,MnO2,Fe2O3,NiO,CuO,ZnO and SnO2,respectively,were investigated from room temperature to 650℃ Using our batch processing program for FT-IR dynamic spectra.The dependence of chemisorbed species of oxygen on tempareture and active oxygen species in oxidative coupling of methane(OCM) were discussed. For alkaline earth oxides and lanthanide earth oxides,a strong infrared band at the range of 1040～1160cm-1 was observed under reaction temperature of OCM,650℃.These bands were blue-shifted from room temperature to 650℃.The bands can be assigned to the chemisorbed species of oxygen,O2- acoording to the Nakamoto's assignment i.e.,1865(O2-)≈1580(O2)≈1097(O2-)≈766(O22-).There was scarcely and infrared band assigned to the species of O22- observed fro these oxides.For other transition metal oxides,however,the infrared band assigned to the species of O22- can be observed but the infrared band assigned to the species of O2- was scaroely observed.国家自然科学基金;福建炼油厂资

Tumor-intrinsic PD-L1 promotes DNA repair in distinct cancers and suppresses PARP inhibitor-induced synthetic lethality

BRCA1-mediated homologous recombination is an important DNA repair mechanism that is the target of FDA-approved PARP inhibitors, yet details of BRCA1-mediated functions remain to be fully elucidated. Similarly, immune checkpoint molecules are targets of FDA-approved cancer immunotherapies, but the biological and mechanistic consequences of their application are incompletely understood. We show here that the immune checkpoint molecule PD-L1 regulates homologous recombination in cancer cells by promoting BRCA1 nuclear foci formation and DNA end resection. Genetic depletion of tumor PD-L1 reduced homologous recombination, increased non-homologous end joining, and elicited synthetic lethality to PARP inhibitors olaparib and talazoparib in vitro in some, but not all, BRCA1 wild-type tumor cells. In vivo, genetic depletion of tumor PD-L1 rendered olaparib-resistant tumors senstive to olaparib. By contrast, anti-PD-L1 immune checkpoint blockade neither enhanced olaparib synthetic lethality nor improved its efficacy in vitro or in wild-type mice. Tumor PD-L1 did not alter expression of BRCA1 or its co-factor BARD1 but instead co-immunoprecipitated with BARD1 and increased BRCA1 nuclear accumulation. Tumor PD-L1 depletion enhanced tumor CCL5 expression and TBK1 activation in vitro, similar to known immune-potentiating effects of PARP inhibitors. Collectively, these data define immune-dependent and -independent effects of PARP inhibitor treatment and genetic tumor PD-L1 depletion. Moreover, they implicate a tumor cell-intrinsic, immune checkpoint-independent function of PD-L1 in cancer cell BRCA1-mediated DNA damage repair with translational potential, including as a treatment response biomarker

Regulation of telomere homeostasis and genomic stability in cancer by N 6-adenosine methylation (m6A).

The role of RNA methylation on N 6-adenosine (m6A) in cancer has been acknowledged, but the underlying mechanisms remain obscure. Here, we identified homeobox containing 1 (HMBOX1) as an authentic target mRNA of m6A machinery, which is highly methylated in malignant cells compared to the normal counterparts and subject to expedited degradation upon the modification. m6A-mediated down-regulation of HMBOX1 causes telomere dysfunction and inactivation of p53 signaling, which leads to chromosome abnormalities and aggressive phenotypes. CRISPR-based, m6A-editing tools further prove that the methyl groups on HMBOX1 per se contribute to the generation of altered cancer genome. In multiple types of human cancers, expression of the RNA methyltransferase METTL3 is negatively correlated with the telomere length but favorably with fractions of altered cancer genome, whereas HMBOX1 mRNA levels show the opposite patterns. Our work suggests that the cancer-driving genomic alterations may potentially be fixed by rectifying particular epitranscriptomic program