Browsing by Author "Xiang, Kun"
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Item Open Access A long non-coding RNA targets microRNA miR-34a to regulate colon cancer stem cell asymmetric division.(Elife, 2016-04-14) Wang, Lihua; Bu, Pengcheng; Ai, Yiwei; Srinivasan, Tara; Chen, Huanhuan Joyce; Xiang, Kun; Lipkin, Steven M; Shen, XilingThe roles of long non-coding RNAs (lncRNAs) in regulating cancer and stem cells are being increasingly appreciated. Its diverse mechanisms provide the regulatory network with a bigger repertoire to increase complexity. Here we report a novel LncRNA, Lnc34a, that is enriched in colon cancer stem cells (CCSCs) and initiates asymmetric division by directly targeting the microRNA miR-34a to cause its spatial imbalance. Lnc34a recruits Dnmt3a via PHB2 and HDAC1 to methylate and deacetylate the miR-34a promoter simultaneously, hence epigenetically silencing miR-34a expression independent of its upstream regulator, p53. Lnc34a levels affect CCSC self-renewal and colorectal cancer (CRC) growth in xenograft models. Lnc34a is upregulated in late-stage CRCs, contributing to epigenetic miR-34a silencing and CRC proliferation. The fact that lncRNA targets microRNA highlights the regulatory complexity of non-coding RNAs (ncRNAs), which occupy the bulk of the genome.Item Open Access Antagonizing the irreversible thrombomodulin-initiated proteolytic signaling alleviates age-related liver fibrosis via senescent cell killing.(Cell research, 2023-07) Pan, Christopher C; Maeso-Díaz, Raquel; Lewis, Tylor R; Xiang, Kun; Tan, Lianmei; Liang, Yaosi; Wang, Liuyang; Yang, Fengrui; Yin, Tao; Wang, Calvin; Du, Kuo; Huang, De; Oh, Seh Hoon; Wang, Ergang; Lim, Bryan Jian Wei; Chong, Mengyang; Alexander, Peter B; Yao, Xuebiao; Arshavsky, Vadim Y; Li, Qi-Jing; Diehl, Anna Mae; Wang, Xiao-FanCellular senescence is a stress-induced, stable cell cycle arrest phenotype which generates a pro-inflammatory microenvironment, leading to chronic inflammation and age-associated diseases. Determining the fundamental molecular pathways driving senescence instead of apoptosis could enable the identification of senolytic agents to restore tissue homeostasis. Here, we identify thrombomodulin (THBD) signaling as a key molecular determinant of the senescent cell fate. Although normally restricted to endothelial cells, THBD is rapidly upregulated and maintained throughout all phases of the senescence program in aged mammalian tissues and in senescent cell models. Mechanistically, THBD activates a proteolytic feed-forward signaling pathway by stabilizing a multi-protein complex in early endosomes, thus forming a molecular basis for the irreversibility of the senescence program and ensuring senescent cell viability. Therapeutically, THBD signaling depletion or inhibition using vorapaxar, an FDA-approved drug, effectively ablates senescent cells and restores tissue homeostasis in liver fibrosis models. Collectively, these results uncover proteolytic THBD signaling as a conserved pro-survival pathway essential for senescent cell viability, thus providing a pharmacologically exploitable senolytic target for senescence-associated diseases.Item Open Access Branched-Chain Amino Acid Accumulation Fuels the Senescence-Associated Secretory Phenotype.(Advanced science (Weinheim, Baden-Wurttemberg, Germany), 2023-11) Liang, Yaosi; Pan, Christopher; Yin, Tao; Wang, Lu; Gao, Xia; Wang, Ergang; Quang, Holly; Huang, De; Tan, Lianmei; Xiang, Kun; Wang, Yu; Alexander, Peter B; Li, Qi-Jing; Yao, Tso-Pang; Zhang, Zhao; Wang, Xiao-FanThe essential branched-chain amino acids (BCAAs) leucine, isoleucine, and valine play critical roles in protein synthesis and energy metabolism. Despite their widespread use as nutritional supplements, BCAAs' full effects on mammalian physiology remain uncertain due to the complexities of BCAA metabolic regulation. Here a novel mechanism linking intrinsic alterations in BCAA metabolism is identified to cellular senescence and the senescence-associated secretory phenotype (SASP), both of which contribute to organismal aging and inflammation-related diseases. Altered BCAA metabolism driving the SASP is mediated by robust activation of the BCAA transporters Solute Carrier Family 6 Members 14 and 15 as well as downregulation of the catabolic enzyme BCAA transaminase 1 during onset of cellular senescence, leading to highly elevated intracellular BCAA levels in senescent cells. This, in turn, activates the mammalian target of rapamycin complex 1 (mTORC1) to establish the full SASP program. Transgenic Drosophila models further indicate that orthologous BCAA regulators are involved in the induction of cellular senescence and age-related phenotypes in flies, suggesting evolutionary conservation of this metabolic pathway during aging. Finally, experimentally blocking BCAA accumulation attenuates the inflammatory response in a mouse senescence model, highlighting the therapeutic potential of modulating BCAA metabolism for the treatment of age-related and inflammatory diseases.Item Open Access Chromatin Remodeling of Colorectal Cancer Liver Metastasis is Mediated by an HGF-PU.1-DPP4 Axis.(Advanced science (Weinheim, Baden-Wurttemberg, Germany), 2021-10) Wang, Lihua; Wang, Ergang; Prado Balcazar, Jorge; Wu, Zhenzhen; Xiang, Kun; Wang, Yi; Huang, Qiang; Negrete, Marcos; Chen, Kai-Yuan; Li, Wei; Fu, Yujie; Dohlman, Anders; Mines, Robert; Zhang, Liwen; Kobayashi, Yoshihiko; Chen, Tianyi; Shi, Guizhi; Shen, John Paul; Kopetz, Scott; Tata, Purushothama Rao; Moreno, Victor; Gersbach, Charles; Crawford, Gregory; Hsu, David; Huang, Emina; Bu, Pengcheng; Shen, XilingColorectal cancer (CRC) metastasizes mainly to the liver, which accounts for the majority of CRC-related deaths. Here it is shown that metastatic cells undergo specific chromatin remodeling in the liver. Hepatic growth factor (HGF) induces phosphorylation of PU.1, a pioneer factor, which in turn binds and opens chromatin regions of downstream effector genes. PU.1 increases histone acetylation at the DPP4 locus. Precise epigenetic silencing by CRISPR/dCas9KRAB or CRISPR/dCas9HDAC revealed that individual PU.1-remodeled regulatory elements collectively modulate DPP4 expression and liver metastasis growth. Genetic silencing or pharmacological inhibition of each factor along this chromatin remodeling axis strongly suppressed liver metastasis. Therefore, microenvironment-induced epimutation is an important mechanism for metastatic tumor cells to grow in their new niche. This study presents a potential strategy to target chromatin remodeling in metastatic cancer and the promise of repurposing drugs to treat metastasis.Item Open Access Exploring the Non-Genetic Reprogramming of Colorectal Cancer and Tumor Microenvironment(2022) Xiang, KunNon-genetic reprogramming, including but not limited to metabolomic and epigenetic, play an equally significant role in cancer development compared to genetic mutations. In most scenarios, non-genetic alterations of tumor cells are associated with their tumor microenvironment, which is highly related to tumor progress and efficiency of the treatment. Nevertheless, how cancer cells adapt their microenvironment by metabolomic or epigenetic reprogramming remains largely unknown. This dissertation started with exploring two scenarios in colorectal cancer (CRC) studies: the metabolic reprogramming of CRC liver metastasis and the epigenetic remodeling of CRC patient-derived models of cancer. In the study of CRC liver metastasis (Chapter 2), we found that metastatic CRC cells promote their fructose metabolism in the liver by upregulating ALDOB. Knocking down ALDOB or restricting the dietary fructose can suppress CRC liver metastasis. In addition, we examined the potential therapeutic approach for liver metastasis with a KHK inhibitor. For the patient-derived models of cancer (PDMC) project (Chapter 3), we developed six matched PT-PDMC sets and performed ATAC-seq and mRNA to study the chromatin accessibilities of CRC cells. We found two-axis chromatin remodeling separating PDMC from the original patient sample (axis #1) as well as the different cancer models (axis #2). PDOX is more similar to PDX than organoids suggesting the chromatin remodeling of CRC cells is under the pressure of tumor microenvironment in PDMC. We also identified the two transcript factors, KLF14 and EGR2, which respond to the xenografts’ environment by footprinting analysis. These two TFs and their downstream gene, EPHA4, altered CRC tumor growth and drug sensitivities. Therefore, chromatin remodeling of different PDMC may interfere with their ability to predict therapeutic outcomes. In the last part of the dissertation (Chapter 4), I developed a novel system that can label and manipulate the tumor niche in situ. This method provides tools for studying the non-genetic alterations of CRC cells when they interact with the tumor microenvironment. Taken together, this dissertation presents a comprehensive understanding of the non-genetic reprogramming of colorectal cancer and its tumor microenvironment. It advances both the knowledge of non-genetic reprogramming in colorectal cancer and technologies to study the tumor microenvironment.
Item Open Access Intravital imaging of mouse embryos(Science, 2020-04-10) Huang, Qiang; Cohen, Malkiel A; Alsina, Fernando C; Devlin, Garth; Garrett, Aliesha; McKey, Jennifer; Havlik, Patrick; Rakhilin, Nikolai; Wang, Ergang; Xiang, Kun; Mathews, Parker; Wang, Lihua; Bock, Cheryl; Ruthig, Victor; Wang, Yi; Negrete, Marcos; Wong, Chi Wut; Murthy, Preetish KL; Zhang, Shupei; Daniel, Andrea R; Kirsch, David G; Kang, Yubin; Capel, Blanche; Asokan, Aravind; Silver, Debra L; Jaenisch, Rudolf; Shen, XilingEmbryonic development is a complex process that is unamenable to direct observation. In this study, we implanted a window to the mouse uterus to visualize the developing embryo from embryonic day 9.5 to birth. This removable intravital window allowed manipulation and high-resolution imaging. In live mouse embryos, we observed transient neurotransmission and early vascularization of neural crest cell (NCC)–derived perivascular cells in the brain, autophagy in the retina, viral gene delivery, and chemical diffusion through the placenta. We combined the imaging window with in utero electroporation to label and track cell division and movement within embryos and observed that clusters of mouse NCC-derived cells expanded in interspecies chimeras, whereas adjacent human donor NCC-derived cells shrank. This technique can be combined with various tissue manipulation and microscopy methods to study the processes of development at unprecedented spatiotemporal resolution.Item Open Access Longitudinal intravital imaging of mouse placenta.(Science advances, 2024-03) Zhu, Xiaoyi; Huang, Qiang; Jiang, Laiming; Nguyen, Van-Tu; Vu, Tri; Devlin, Garth; Shaima, Jabbar; Wang, Xiaobei; Chen, Yong; Ma, Lijun; Xiang, Kun; Wang, Ergang; Rong, Qiangzhou; Zhou, Qifa; Kang, Yubin; Asokan, Aravind; Feng, Liping; Hsu, Shiao-Wen D; Shen, Xiling; Yao, JunjieStudying placental functions is crucial for understanding pregnancy complications. However, imaging placenta is challenging due to its depth, volume, and motion distortions. In this study, we have developed an implantable placenta window in mice that enables high-resolution photoacoustic and fluorescence imaging of placental development throughout the pregnancy. The placenta window exhibits excellent transparency for light and sound. By combining the placenta window with ultrafast functional photoacoustic microscopy, we were able to investigate the placental development during the entire mouse pregnancy, providing unprecedented spatiotemporal details. Consequently, we examined the acute responses of the placenta to alcohol consumption and cardiac arrest, as well as chronic abnormalities in an inflammation model. We have also observed viral gene delivery at the single-cell level and chemical diffusion through the placenta by using fluorescence imaging. Our results demonstrate that intravital imaging through the placenta window can be a powerful tool for studying placenta functions and understanding the placental origins of adverse pregnancy outcomes.Item Open Access Rapid tissue prototyping with micro-organospheres.(Stem cell reports, 2022-09) Wang, Zhaohui; Boretto, Matteo; Millen, Rosemary; Natesh, Naveen; Reckzeh, Elena S; Hsu, Carolyn; Negrete, Marcos; Yao, Haipei; Quayle, William; Heaton, Brook E; Harding, Alfred T; Bose, Shree; Driehuis, Else; Beumer, Joep; Rivera, Grecia O; van Ineveld, Ravian L; Gex, Donald; DeVilla, Jessica; Wang, Daisong; Puschhof, Jens; Geurts, Maarten H; Yeung, Athena; Hamele, Cait; Smith, Amber; Bankaitis, Eric; Xiang, Kun; Ding, Shengli; Nelson, Daniel; Delubac, Daniel; Rios, Anne; Abi-Hachem, Ralph; Jang, David; Goldstein, Bradley J; Glass, Carolyn; Heaton, Nicholas S; Hsu, David; Clevers, Hans; Shen, XilingIn vitro tissue models hold great promise for modeling diseases and drug responses. Here, we used emulsion microfluidics to form micro-organospheres (MOSs), which are droplet-encapsulated miniature three-dimensional (3D) tissue models that can be established rapidly from patient tissues or cells. MOSs retain key biological features and responses to chemo-, targeted, and radiation therapies compared with organoids. The small size and large surface-to-volume ratio of MOSs enable various applications including quantitative assessment of nutrient dependence, pathogen-host interaction for anti-viral drug screening, and a rapid potency assay for chimeric antigen receptor (CAR)-T therapy. An automated MOS imaging pipeline combined with machine learning overcomes plating variation, distinguishes tumorspheres from stroma, differentiates cytostatic versus cytotoxic drug effects, and captures resistant clones and heterogeneity in drug response. This pipeline is capable of robust assessments of drug response at individual-tumorsphere resolution and provides a rapid and high-throughput therapeutic profiling platform for precision medicine.