Publications by authors named "Wa Xian"

63 Publications

Molecular targeting therapies for neuroblastoma: Progress and challenges.

Med Res Rev 2021 03 6;41(2):961-1021. Epub 2020 Nov 6.

Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas, USA.

There is an urgent need to identify novel therapies for childhood cancers. Neuroblastoma is the most common pediatric solid tumor, and accounts for ~15% of childhood cancer-related mortality. Neuroblastomas exhibit genetic, morphological and clinical heterogeneity, which limits the efficacy of existing treatment modalities. Gaining detailed knowledge of the molecular signatures and genetic variations involved in the pathogenesis of neuroblastoma is necessary to develop safer and more effective treatments for this devastating disease. Recent studies with advanced high-throughput "omics" techniques have revealed numerous genetic/genomic alterations and dysfunctional pathways that drive the onset, growth, progression, and resistance of neuroblastoma to therapy. A variety of molecular signatures are being evaluated to better understand the disease, with many of them being used as targets to develop new treatments for neuroblastoma patients. In this review, we have summarized the contemporary understanding of the molecular pathways and genetic aberrations, such as those in MYCN, BIRC5, PHOX2B, and LIN28B, involved in the pathogenesis of neuroblastoma, and provide a comprehensive overview of the molecular targeted therapies under preclinical and clinical investigations, particularly those targeting ALK signaling, MDM2, PI3K/Akt/mTOR and RAS-MAPK pathways, as well as epigenetic regulators. We also give insights on the use of combination therapies involving novel agents that target various pathways. Further, we discuss the future directions that would help identify novel targets and therapeutics and improve the currently available therapies, enhancing the treatment outcomes and survival of patients with neuroblastoma.
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http://dx.doi.org/10.1002/med.21750DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7906923PMC
March 2021

Protocol for Cloning Epithelial Stem Cell Variants from Human Lung.

STAR Protoc 2020 Sep 9;1(2). Epub 2020 Jul 9.

Stem Cell Center, Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA.

The plurality of clonogenic cells derived from human lung includes a spectrum of diverse p63+ stem cells responsible for the regeneration of normal epithelial tissue and disease-associated metaplastic lesions. Here, we report protocols for the cloning, expansion, and characterization of these stem cell variants, which in general assist in analyses of stem cell heterogeneity, genome editing, drug screening, and regenerative medicine. For complete details on the use and execution of this protocol, please refer to Kumar et al. (2011), Zuo et al. (2015), and Rao et al. (2020).
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http://dx.doi.org/10.1016/j.xpro.2020.100063DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7529324PMC
September 2020

Targeting the p53-MDM2 pathway for neuroblastoma therapy: Rays of hope.

Cancer Lett 2021 01 29;496:16-29. Epub 2020 Sep 29.

Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX, 77204, USA; Drug Discovery Institute, University of Houston, Houston, TX, 77204, USA. Electronic address:

Despite being the subject of extensive research and clinical trials, neuroblastoma remains a major therapeutic challenge in pediatric oncology. The p53 protein is a central safeguard that protects cells against genome instability and malignant transformation. Mutated TP53 (the gene encoding p53) is implicated in many human cancers, but the majority of neuroblastomas have wild type p53 with intact transcriptional function. In fact, the TP53 mutation rate does not exceed 1-2% in neuroblastomas. However, overexpression of the murine double minute 2 (MDM2) gene in neuroblastoma is relatively common, and leads to inhibition of p53. It is also associated with other non-canonical p53-independent functions, including drug resistance and increased translation of MYCN and VEGF mRNA. The p53-MDM2 pathway in neuroblastoma is also modulated at several different molecular levels, including via interactions with other proteins (MYCN, p14). In addition, the overexpression of MDM2 in tumors is linked to a poorer prognosis for cancer patients. Thus, restoring p53 function by inhibiting its interaction with MDM2 is a potential therapeutic strategy for neuroblastoma. A number of p53-MDM2 antagonists have been designed and studied for this purpose. This review summarizes the current understanding of p53 biology and the p53-dependent and -independent oncogenic functions of MDM2 in neuroblastoma, and also the regulation of the p53-MDM2 axis in neuroblastoma. This review also highlights the use of MDM2 as a molecular target for the disease, and describes the MDM2 inhibitors currently being investigated in preclinical and clinical studies. We also briefly explain the various strategies that have been used and future directions to take in the development of effective MDM2 inhibitors for neuroblastoma.
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http://dx.doi.org/10.1016/j.canlet.2020.09.023DOI Listing
January 2021

Mystery Solving: Acid Reflux and Cell Mobility in Barrett's Esophagus and Esophageal Adenocarcinoma.

Cell Mol Gastroenterol Hepatol 2020 27;10(3):639-640. Epub 2020 Jun 27.

University of Houston, Houston, Texas.

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http://dx.doi.org/10.1016/j.jcmgh.2020.06.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7474153PMC
June 2020

Regenerative Metaplastic Clones in COPD Lung Drive Inflammation and Fibrosis.

Cell 2020 05 15;181(4):848-864.e18. Epub 2020 Apr 15.

Stem Cell Center, Department of Biology and Biochemistry, University of Houston, Houston, TX 77003, USA. Electronic address:

Chronic obstructive pulmonary disease (COPD) is a progressive condition of chronic bronchitis, small airway obstruction, and emphysema that represents a leading cause of death worldwide. While inflammation, fibrosis, mucus hypersecretion, and metaplastic epithelial lesions are hallmarks of this disease, their origins and dependent relationships remain unclear. Here we apply single-cell cloning technologies to lung tissue of patients with and without COPD. Unlike control lungs, which were dominated by normal distal airway progenitor cells, COPD lungs were inundated by three variant progenitors epigenetically committed to distinct metaplastic lesions. When transplanted to immunodeficient mice, these variant clones induced pathology akin to the mucous and squamous metaplasia, neutrophilic inflammation, and fibrosis seen in COPD. Remarkably, similar variants pre-exist as minor constituents of control and fetal lung and conceivably act in normal processes of immune surveillance. However, these same variants likely catalyze the pathologic and progressive features of COPD when expanded to high numbers.
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http://dx.doi.org/10.1016/j.cell.2020.03.047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7294989PMC
May 2020

Cloning of ground-state intestinal stem cells from endoscopic biopsy samples.

Nat Protoc 2020 05 1;15(5):1612-1627. Epub 2020 Apr 1.

Stem Cell Center, Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA.

'Adult' or 'somatic' stem cells harbor an intrinsic ability to regenerate tissues. Heterogeneity of such stem cells along the gastrointestinal tract yields the known segmental specificity of this organ and may contribute to the pathology of certain enteric conditions. Here we detail technology for the generation of 'libraries' of clonogenic cells from 1-mm-diamter endoscopic biopsy samples from the human gastrointestinal tract. Each of the 150-300 independent clones in a typical stem cell library can be clonally expanded to billions of cells in a few weeks while maintaining genomic stability and the ability to undergo multipotent differentiation to the specific epithelia from which the sample originated. The key to this methodology is the intrinsic immortality of normal intestinal stem cells (ISCs) and culture systems that maintain them as highly immature, ground-state ISCs marked by a single-cell clonogenicity of 70% and a corresponding 250-fold proliferative advantage over spheroid technologies. Clonal approaches such as this enhance the resolution of molecular genetics, make genome editing easier, and may be useful in regenerative medicine, unravelling heterogeneity in disease, and facilitating drug discovery.
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http://dx.doi.org/10.1038/s41596-020-0298-4DOI Listing
May 2020

Evidence for a Novel Endometrioid Carcinogenic Sequence in the Fallopian Tube With Unique Beta-Catenin Expression.

Int J Gynecol Pathol 2020 Mar;39(2):163-169

Epithelial proliferations in the fallopian tube have been characterized by some as stem cell outgrowths (SCOUTs) and divided into type I and type II. Type II SCOUTs exhibit diffuse cellular beta-catenin nuclear staining (β-catenin), implying a CTNNB1 mutation. SCOUTs are more common in perimenopausal and postmenopausal women and are associated with ovarian cancer but have not been linked directly to malignancy. We analyzed type II SCOUTs in various gynecologic conditions, and searched for endometrioid atypical hyperplasias (tubal endometrioid intraepithelial neoplasia) or adenocarcinomas in the tube. β-catenin SCOUT frequency in cases of neoplasia was 66.7% per case and 30.7% per nonfimbrial cross-section for uterine endometrioid carcinomas versus 25% and 13.3% for controls, respectively (P=0.02 and 0.09). Multiple (3 or more) β-catenin SCOUTs in a single section were uncommon; 6 of 9 were associated with a carcinoma or proliferative lesion in the endometrium. Tubal endometrioid intraepithelial neoplasia/atypical hyperplasia displayed complex growth, including focal cribriform growth patterns and squamous morules. Two cases of type II SCOUTs associated with tubal endometrioid intraepithelial neoplasia/atypical hyperplasia and/or adenocarcinomas in the fallopian tube were identified, both of which coexisted with a separate endometrioid adenocarcinoma, one with bilateral ovarian endometrioid adenocarcinomas. Both benign and neoplastic tubal lesions were β-catenin. This report is the first to link components of a unique β-catenin endometrioid carcinogenic sequence in the fallopian tube. It further emphasizes the multifocal nature of endometrioid neoplasia in the female genital tract and poses questions regarding the frequency and biologic underpinnings of β-catenin proliferations in the oviduct.
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http://dx.doi.org/10.1097/PGP.0000000000000590DOI Listing
March 2020

Unlimited expansion of intestinal stem cells from a wide range of ages.

Integr Mol Med 2019 Aug 15;6(4). Epub 2019 Jul 15.

Institute of Molecular Medicine, McGovern Medical School of The University of Texas, Health Science Center, Houston, Texas 77030, USA.

The recent technical advance in cloning and culturing ground-state intestinal stem cells (ISC) provides us an opportunity of accurate assessment of age-related impact on the function of highly proliferative intestinal stem cells. Our ability of indefinitely and robustly expanding single-stem-cell derived pedigrees allows us to study intestinal stem cells at the clonal level. Interestingly, comparable number of ISC clones was yielded from 1mm endoscopic biopsy of all donors despite the age. They were passaged as pedigrees and expanded to 1 billion cells in approximately sixty days without changes in stemness demonstrated by clonogenicity and multipotency. Therefore, our study shows that ISCs from a wide range of ages can be cloned and expanded to unlimited number with similar efficiency and stability. These patient-derived ISCs harbor intrinsic immortality and are ideal for autologous transplantation, supporting the promise of adult-stem-cell based personalized medicine.
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http://dx.doi.org/10.15761/IMM.1000375DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6713279PMC
August 2019

Meeting report from the 2018 12th Biennial Ovarian Cancer Research Symposium detection and prevention of ovarian cancer.

Int J Gynecol Cancer 2019 08;29(Suppl 2):s2-s6

Sylvester Comprehensive Cancer Center, Miami, Florida, USA.

The objective of this review is to summarize recent research advances in the detection and prevention of ovarian cancer and discuss the experts' opinions of future directions. The 12th Biennial Ovarian Cancer Research Symposium was held in Seattle, Washington, in September 2018. At this meeting, experts in ovarian cancer research gathered to present and discuss recent breakthroughs and their visions of future ovarian cancer research. Session 1 of the symposium focused on the detection and prevention of ovarian cancer. It included two invited oral presentations from Ranjit Manchanda, MD, PhD (Barts Cancer Institute) and Rosana Risques, PhD (University of Washington). Another eight oral presentations were selected from abstract submissions. Fifteen abstracts were presented in poster format. These presentations covered topics including cellular origin of high-grade serous cancer, risk factors for ovarian cancer, new methods for early detection of ovarian cancer, mechanisms underlying ovarian cancer development, and new therapeutic approaches for preventing ovarian cancer from forming or progressing. In conclusion, a clear understanding of the cellular origin and molecular mechanisms underlying the initiation of high-grade serous cancer is essential for developing effective means for early detection and prevention of this most devastating type of ovarian cancer. Recognizing the complexity of ovarian cancer and appreciating that ovarian cancer is not a single disease will help us to generate proper models, design rational experiments, and collect and analyze patient data in a meaningful way. A concerted effort in the field will help to bridge the basic science and clinical applications and lead to more precise and effective detection and treatment.
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http://dx.doi.org/10.1136/ijgc-2019-000454DOI Listing
August 2019

Microenvironment meets lineage complexity in junctional tumorigenesis.

Nat Commun 2019 08 23;10(1):3829. Epub 2019 Aug 23.

Department of Biology and Biochemistry, University of Houston, Houston, TX, 77204, USA.

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http://dx.doi.org/10.1038/s41467-019-11651-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6707302PMC
August 2019

Circadian period 2: a missing beneficial factor in sickle cell disease by lowering pulmonary inflammation, iron overload, and mortality.

FASEB J 2019 09 29;33(9):10528-10537. Epub 2019 Jun 29.

Department of Biochemistry and Molecular Biology, The University of Texas McGovern Medical School, Houston, Texas, USA.

The circadian clock is important for cellular and organ function. However, its function in sickle cell disease (SCD), a life-threatening hemolytic disorder, remains unknown. Here, we performed an unbiased microarray screen, which revealed significantly altered expression of circadian rhythmic genes, inflammatory response genes, and iron metabolic genes in SCD Berkeley transgenic mouse lungs compared with controls. Given the vital role of period 2 (Per2) in the core clock and the unrecognized role of Per2 in SCD, we transplanted the bone marrow (BM) of SCD mice to mice, which revealed that Per2 expression was up-regulated in SCD mouse lung. Next, we transplanted the BM of SCD mice to period 1 () [ ()] and wild-type mice, respectively. We discovered that mice transplanted with SCD BM (SCD → ) displayed severe irradiation sensitivity and were more susceptible to an early death. Although we observed an increase of peripheral inflammatory cells, we did not detect differences in erythrocyte sickling. However, there was further lung damage due to elevated pulmonary congestion, inflammatory cell infiltration, iron overload, and secretion of IL-6 in lavage fluid. Overall, we demonstrate that is beneficial to counteract elevated systemic inflammation, lung tissue inflammation, and iron overload in SCD.-Adebiyi, M. G., Zhao, Z., Ye, Y., Manalo, J., Hong, Y., Lee, C. C., Xian, W., McKeon, F., Culp-Hill, R., D' Alessandro, A., Kellems, R. E., Yoo, S.-H., Han, L., Xia, Y. Circadian period 2: a missing beneficial factor in sickle cell disease by lowering pulmonary inflammation, iron overload, and mortality.
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http://dx.doi.org/10.1096/fj.201900246RRDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6988849PMC
September 2019

The Cellular Origin of Barrett's Esophagus and Its Stem Cells.

Adv Exp Med Biol 2019 ;1123:55-69

Department of Biology and Biochemistry, University of Houston, Houston, TX, USA.

The incidence of esophageal adenocarcinoma is rapidly increasing in Western countries. This is despite the introduction of sophisticated endoscopic techniques and our ability to readily monitor the presumed precursor lesion known as Barrett's esophagus. Preemptive approaches, including radiofrequency ablation (RFA), and photodynamic therapy (PDT) for Barrett's esophagus and dysplasia are achieving dramatic initial results. Although the long-term efficacy of these nonspecific ablative therapies is awaiting longitudinal studies, reports of recurrences are increasing. More targeted therapies, particularly directed at the stem cells of Barrett's esophagus, demand knowing the origin of this intestinal metaplasia (IM). The prevailing concept holds that Barrett's esophagus arises from the "transcommitment" of esophageal stem cells to produce an intestine-like epithelium. An alternative explanation derives from the discovery of a discrete population of residual embryonic cells (RECs) existing at the gastroesophageal junction in normal individuals that expands and colonizes regions of the esophagus denuded by chronic reflux. These RECs form IM within days of esophageal injury, suggesting a novel mechanism of tumorigenesis.A corollary of this work is that the Barrett's stem cell is distinct from that of the squamous epithelium and, once identified, will form the basis of new preemptive strategies for addressing Barrett's and its related neoplasia.
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http://dx.doi.org/10.1007/978-3-030-11096-3_5DOI Listing
August 2019

Biobanking Organoids or Ground-State Stem Cells?

J Clin Med 2018 Dec 16;7(12). Epub 2018 Dec 16.

Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA.

Autologous transplantation of human epidermal stem cells cultured in Green's method is one of the first examples of utilizing adult stem cells in regenerative medicine. Using the same method, we cloned p63-expressing distal airway stem cells and showed their essential role in lung regeneration in a mouse model of acute respiratory distress syndrome. However, adult stem cells of columnar epithelial tissues had until recently evaded all attempts at cloning. To address this issue, we developed a novel technology that enabled cloning ground-state stem cells of the columnar epithelium. The adaption of this technology to clone stem cells of cancer precursors furthered our understanding of the dynamics of processes such as clonal evolution and dominance in Barrett's esophagus, as well as for testing platforms for chemical screening. Taken together, the properties of these ground-state stem cells, including unlimited propagation, genomic stability, and regio-specificity, make them ideal for regenerative medicine, disease modeling and drug discovery.
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http://dx.doi.org/10.3390/jcm7120555DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6306851PMC
December 2018

Frontiers in the Pathology and Pathogenesis of Ovarian Cancer: Cancer Precursors and "Precursor Escape".

Hematol Oncol Clin North Am 2018 12;32(6):915-928

Department of Pathology, Harvard Medical School, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA. Electronic address:

This article summarizes the pathogenesis of ovarian carcinoma, focusing on the paradox of high-grade serous carcinogenesis. The fallopian tube is the prime site of origin in early serous cancers. Because a subset of serous cancers is associated with early serous proliferations absent intramucosal carcinomas, "precursor escape" is emerging, whereby some advanced cancers trace their roots to early serous proliferations. This has parallels in the endometriosis model and opens up a novel mechanism by which advanced malignancy could emerge without an obvious tubal carcinoma. The impact of this concept on classification of serous cancer and expectations from preventive strategies are discussed.
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http://dx.doi.org/10.1016/j.hoc.2018.07.013DOI Listing
December 2018

An Efficient Method for Cloning Gastrointestinal Stem Cells From Patients via Endoscopic Biopsies.

Gastroenterology 2019 01 6;156(1):20-23. Epub 2018 Oct 6.

Institute of Molecular Medicine, McGovern Medical School of University of Texas Health Science Center, Houston, Texas; Department of Biochemistry and Molecular Biology, McGovern Medical School of University of Texas Health Science Center, Houston, Texas. Electronic address:

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http://dx.doi.org/10.1053/j.gastro.2018.08.062DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6309951PMC
January 2019

Evidence for lineage continuity between early serous proliferations (ESPs) in the Fallopian tube and disseminated high-grade serous carcinomas.

J Pathol 2018 11 27;246(3):344-351. Epub 2018 Sep 27.

Division of Women's and Perinatal Pathology, Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts, USA.

The distal Fallopian tube is a site of origin for many 'ovarian' high-grade serous carcinomas (HGSCs) with intraepithelial carcinomas (STICs) that share identical TP53 mutations with metastatic tumors. TP53 mutation-positive early serous proliferations (ESPs) comprise a spectrum including p53 signatures and serous tubal intraepithelial lesions (STILs) and are not considered malignant; however, ESPs are often the only abnormality found in Fallopian tubes of women with metastatic HGSC. The purpose of this study was to determine if a relationship exists between isolated ESPs and concurrent metastatic HGSCs in the absence of STIC. Fallopian tubes from 32 HGSCs without a co-existing STIC/HGSC in the endosalpinx were exhaustively sectioned. The presence of either STIC/HGSC or ESP in the endosalpinx was documented and DNA from tissues containing ESPs, concurrent HGSC, and control epithelia were interrogated for TP53 mutations by targeted amplicon-based sequencing with average coverage reads >4000 across DNA replicate samples. Serial sectioning revealed a previously unrecognized STIC/HGSC in 3 of 32 (9.3%) and ESPs in 13 (40.6%). Twelve contained TP53 mutations. Nine (75%) shared identical TP53 mutations with concurrent HGSCs, four at high (≥ 5%) and five at low (< 5%) allele frequency. All control epithelia were TP53 mutation-negative. This study, for the first time, indicates lineage identity between ESPs in the distal tube and some metastatic HGSCs via a shared site-specific TP53 mutation. It supports a novel serous carcinogenic sequence in which an ESP could eventually culminate in a metastatic serous cancer via 'precursor escape' and would explain the apparent sudden onset of cancers without co-existing STICs. This paradigm for serous cancer development underscores the likelihood that multiple precursor types in the Fallopian tube contribute to serous cancer development with implications for the evolution, pathologic classification, and prevention of this lethal malignancy. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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http://dx.doi.org/10.1002/path.5145DOI Listing
November 2018

Demise of lung transplants: exposing critical gaps in understanding lung stem cells.

J Thorac Dis 2018 Apr;10(Suppl 9):S1016-S1019

Institute of Molecular Medicine, McGovern Medical School, University of Texas Health, Sciences Center, Department of Biology and Biochemistry, Stem Cell Center, University of Houston, Houston, TX, USA.

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http://dx.doi.org/10.21037/jtd.2018.03.146DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5949424PMC
April 2018

TAp63 as a guardian of female germ line integrity.

Nat Struct Mol Biol 2018 03;25(3):201-202

Department of Biology and Biochemistry, University of Houston, Houston, TX, USA.

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http://dx.doi.org/10.1038/s41594-018-0041-9DOI Listing
March 2018

Ground-State Stem Cells: A Novel Approach for Adult Stem Cell Research.

J Pediatr Pediatr Med 2018 31;2(6):7-10. Epub 2018 Dec 31.

Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204, USA.

A robust and reliable culture system of adult stem cells is essential for applying the cutting-edge technologies of drug screening, gene editing, and genomics to stem cell research necessary for breakthroughs in this field. In addition, personalized regenerative medicine based on autologous transplantation requires our ability to clone and expand the numbers of these stem cells . In comparison to the 3D "organoid" culture system that shows limited ability to propagate stem cells as the majority of cells are differentiated or transit amplifying cells, ground-state stem cell culture system is a novel technology that permits long-lived adult stem cells to maintain immaturity, self-renewal capacity, multi-potency and genomic stability despite long-term culturing in a 2D system. The robustness, reliability and easy-to-use features of this new technology bypass the deficiencies of 3D organoid culture systems and provided unlimited stem cell sources for research, therapeutic use, and drug discovery.
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http://dx.doi.org/10.29245/2578-2940/2018/6.1140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6448798PMC
December 2018

FABP1 and Hepar expression levels in Barrett's esophagus and associated neoplasia in an Asian population.

Dig Liver Dis 2017 Oct 27;49(10):1104-1109. Epub 2017 Jul 27.

Department of Pathology, National University Health System, Singapore. Electronic address:

Introduction: Barrett's esophagus (BE) is a premalignant condition associated with esophageal adenocarcinoma (EAC). Evidence highlights that EAC is associated with an estimated 5-year survival of approximately 10-15%. Therefore, there is a need to determine which biomarkers are of value in the diagnosis of BE and beyond. The aim of our study was to evaluate the clinical significance of markers known to be expressed across BE and associated neoplasia.

Methods: Retrospective tissues were obtained from columnar lined esophagus (CLE) without goblet cells (n=22), BE (n=29), dysplasia (n=14), and EAC (n=10). Standardised immunohistochemistry for FABP1, Hepar, CDH17, and CDX2 were performed followed by quantitative staining and statistical analysis.

Results: FABP1 expression was negligible in CLE and was highest in BE, with a further decrease in expression in dysplasia and EAC. Hepar expression was also negligible in CLE and was highest in dysplasia and BE, with a reduced expression in EAC. CDH17 and CDX2 showed a significantly higher expression in BE, dysplasia, and EAC compared to CLE.

Conclusion: All 4 markers were excellent diagnostic panels to clearly discriminate BE from CLE. Moreover, as FABP1 and Hepar have different expression levels in dysplasia and EAC, these markers could function as key diagnostic aids in helping to determine the state of disease progression.
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http://dx.doi.org/10.1016/j.dld.2017.06.014DOI Listing
October 2017

Barrett's Stem Cells as a Unique and Targetable Entity.

Cell Mol Gastroenterol Hepatol 2017 Jul 26;4(1):161-164. Epub 2017 Apr 26.

Department of Biology and Biochemistry, University of Houston, Houston, Texas, and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.

Although metaplasias have always attracted because of their strangeness, it is now clear they represent precursors for some of the most intractable human cancers. Despite this notoriety, they remain curiously understudied, and even their origins have been the subject of acrimonious debate stretching back to Virchow in the 19th century. Barrett's esophagus, with its high incidence, easy endoscopic access, and strong link to esophageal adenocarcinoma, would seem an ideal opportunity to address the origin problem. However, the field has settled into an uneasy status quo marked by no fewer than 4 parallel hypotheses, each of which is said to suffer fatal flaws. We favor one of these deficient hypotheses, that Barrett's arises from a distinct lineage of junctional cells present in all normal individuals, and discuss efforts to shore it up. It will be important to resolve this dialectic so that preemptive strategies for the eradication of Barrett's can reach patient care.
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http://dx.doi.org/10.1016/j.jcmgh.2017.04.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5454139PMC
July 2017

Endoscopic modalities for the diagnosis of Barrett's oesophagus.

United European Gastroenterol J 2016 Dec 15;4(6):733-740. Epub 2015 Dec 15.

National University Hospital, Singapore.

Barrett's oesophagus is a pre-malignant condition associated with the development of oesophageal adenocarcinoma. Currently white light endoscopy and biopsy is the mainstay diagnostic tool. Yet this approach is troubled by issues related to cumbersome biopsy sampling, biopsy sampling errors and cost. Therefore in order to overcome such adversity, there needs to be evolutionary advancement in terms of diagnosis, which should address these concerns and ideally enhance risk stratification in order to provide timely management in real time. This review highlights the current endoscopic tools aimed to enhance the diagnosis of Barrett's oesophagus and its subsequent progression.
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http://dx.doi.org/10.1177/2050640615619281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5386224PMC
December 2016

Mutational spectrum of Barrett's stem cells suggests paths to initiation of a precancerous lesion.

Nat Commun 2016 Jan 19;7:10380. Epub 2016 Jan 19.

Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.

The precancerous lesion known as Barrett's oesophagus can evolve to oesophageal adenocarcinoma in decades-long processes of regenerative growth. Here we report the isolation and propagation of distinct, patient-matched stem cells of Barrett's, gastric and oesophageal epithelia that yield divergent tumour types following in vitro transformation and xenografting. Genomic analyses reveal a broad mutational spectrum unique to Barrett's stem cells that likely reflects their risk for oncogenesis. Remarkably, 25% of cases show no cancer-related genomic changes, suggesting that Barrett's initiates without driver mutations. Most cases, however, sustain patterns of deletions almost identical to adenocarcinoma though tumour-associated gene amplifications were absent. Notably, those suspected of low-grade dysplasia have p53 mutations or undergo amplifications of proto-oncogenes and receptor tyrosine kinases, implicating these events in lethal transitions. Our findings suggest paths for the initiation and progression of Barrett's and define a discrete stem cell underlying its regenerative growth whose eradication could prevent oesophageal adenocarcinoma.
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http://dx.doi.org/10.1038/ncomms10380DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4735693PMC
January 2016

In vitro and in vivo correlates of physiological and neoplastic human Fallopian tube stem cells.

J Pathol 2016 Mar 9;238(4):519-530. Epub 2016 Jan 9.

The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA.

High-grade serous cancer (HGSC) progresses to advanced stages without symptoms and the 5-year survival rate is a dismal 30%. Recent studies of ovaries and Fallopian tubes in patients with BRCA1 or BRCA2 mutations have documented a pre-metastatic intramucosal neoplasm that is found almost exclusively in the Fallopian tube, termed 'serous tubal intraepithelial carcinoma' or STIC. Moreover, other proliferations, termed p53 signatures, secretory cell outgrowths (SCOUTs), and lower-grade serous tubal intraepithelial neoplasms (STINs) fall short of STIC but share similar alterations in expression, in keeping with an underpinning of genomic disturbances involved in, or occurring in parallel with, serous carcinogenesis. To gain insight into the cellular origins of this unique tubal pathway to high-grade serous cancer, we cloned and both immortalized and transformed Fallopian tube stem cells (FTSCs). We demonstrated that pedigrees of FTSCs were capable of multipotent differentiation and that the tumours derived from transformed FTSCs shared the histological and molecular features of HGSC. We also demonstrated that altered expression of some biomarkers seen in transformed FTSCs and HGSCs (stathmin, EZH2, CXCR4, CXCL12, and FOXM1) could be seen as well in immortalized cells and their in vivo counterparts SCOUTs and STINs. Thus, a whole-genome transcriptome analysis comparing FTSCs, immortalized FTSCs, and transformed FTSCs showed a clear molecular progression sequence that is recapitulated by the spectrum of accumulated perturbations characterizing the range of proliferations seen in vivo. Biomarkers unique to STIC relative to normal tubal epithelium provide a basis for novel detection approaches to early HGSC, but must be viewed critically given their potential expression in lesser proliferations. Perturbations shared by both immortalized and transformed FTSCs may provide unique early targets for prevention strategies. Central to these efforts has been the ability to clone and perpetuate multipotent FTSCs.
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http://dx.doi.org/10.1002/path.4649DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4895925PMC
March 2016

Cloning and variation of ground state intestinal stem cells.

Nature 2015 Jun 3;522(7555):173-8. Epub 2015 Jun 3.

1] The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut 06032, USA [2] Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, Connecticut 06032, USA [3] Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts 02118, USA [4] Department of Medicine, National University of Singapore, 119228 Singapore [5] Multiclonal Therapeutics, Inc., Farmington, Connecticut 06032, USA.

Stem cells of the gastrointestinal tract, pancreas, liver and other columnar epithelia collectively resist cloning in their elemental states. Here we demonstrate the cloning and propagation of highly clonogenic, 'ground state' stem cells of the human intestine and colon. We show that derived stem-cell pedigrees sustain limited copy number and sequence variation despite extensive serial passaging and display exquisitely precise, cell-autonomous commitment to epithelial differentiation consistent with their origins along the intestinal tract. This developmentally patterned and epigenetically maintained commitment of stem cells is likely to enforce the functional specificity of the adult intestinal tract. Using clonally derived colonic epithelia, we show that toxins A or B of the enteric pathogen Clostridium difficile recapitulate the salient features of pseudomembranous colitis. The stability of the epigenetic commitment programs of these stem cells, coupled with their unlimited replicative expansion and maintained clonogenicity, suggests certain advantages for their use in disease modelling and regenerative medicine.
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http://dx.doi.org/10.1038/nature14484DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4853906PMC
June 2015

Microanatomy of the cervical and anorectal squamocolumnar junctions: a proposed model for anatomical differences in HPV-related cancer risk.

Mod Pathol 2015 Jul 15;28(7):994-1000. Epub 2015 May 15.

Department of Pathology, University of Liege, Liege, Belgium.

Human papilloma virus (HPV) infection causes cancers and their precursors (high-grade squamous intraepithelial lesions) near cervical and anal squamocolumnar junctions. Recently described cervical squamocolumnar junction cells are putative residual embryonic cells near the cervical transformation zone. These cells appear multipotential and share an identical immunophenotype (strongly CK7-positive) with over 90% of high-grade squamous intraepithelial lesions and cervical carcinomas. However, because the number of new cervical cancers discovered yearly world wide is 17-fold that of anal cancer, we posed the hypothesis that this difference in cancer risk reflects differences in the transition zones at the two sites. The microanatomy of the normal anal transformation zone (n=37) and topography and immunophenotype of anal squamous neoplasms (n=97) were studied. A discrete anal transition zone was composed of multilayered CK7-positive/p63-negative superficial columnar cells and an uninterrupted layer of CK7-negative/p63-positive basal cells. The CK7-negative/p63-positive basal cells were continuous with-and identical in appearance to-the basal cells of the mature squamous epithelium. This was in contrast to the cervical squamocolumnar junction, which harbored a single-layered CK7-positive/p63-negative squamocolumnar junction cell population. Of the 97 anal intraepithelial neoplasia/squamous cell carcinomas evaluated, only 27% (26/97) appeared to originate near the anal transition zone and only 23% (22/97) were CK7-positive. This study thus reveals two fundamental differences between the anus and the cervix: (1) the anal transition zone does not harbor a single monolayer of residual undifferentiated embryonic cells and (2) the dominant tumor immunophenotype is in keeping with an origin in metaplastic (CK7-negative) squamous rather than squamocolumnar junction (CK7-positive) epithelium. The implication is that, at birth, the embryonic cells in the anal transition zone have already begun to differentiate, presenting a metaplasia that-similar to vaginal and vulvar epithelium-is less prone to HPV-directed carcinogenesis. This in turn underscores the link between cancer risk and a very small and discrete population of vulnerable squamocolumnar junction cells in the cervix.
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http://dx.doi.org/10.1038/modpathol.2015.54DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4490106PMC
July 2015

Carcinogenic HPV infection in the cervical squamo-columnar junction.

J Pathol 2015 Jul 27;236(3):265-71. Epub 2015 Apr 27.

Laboratory of Experimental Pathology, GIGA-Cancer, University of Liège, Liège, Belgium.

Recent studies have suggested the involvement of a unique population of cells at the cervical squamo-columnar junction (SCJ) in the pathogenesis of early (squamous intraepithelial lesion or SIL) and advanced (squamous cell and adeno-carcinomas) cervical neoplasia. However, there is little evidence to date showing that SCJ cells harbour carcinogenic HPV or are instrumental in the initial phases of neoplasia. This study was designed to (1) determine if normal-appearing SCJ cells contained evidence of carcinogenic HPV infection and (2) trace their transition to early SIL. Sections of cervix from high-risk reproductive age women were selected and SCJ cells were analysed by using several techniques which increasingly implicated HPV infection: HPV DNA (genotyping and in situ hybridization)/RNA (PCR), immunostaining for HPV16 E2 (an early marker of HPV infection), p16(ink4), Ki67, and HPV L1 protein. In 22 cases with a history of SIL and no evidence of preneoplastic lesion in the excision specimen, HPV DNA was isolated from eight of ten with visible SCJ cells, six of which were HPV16/18 DNA-positive. In five of these latter cases, the SCJ cells were positive for p16(ink4) and/or HPV E2. Transcriptionally active HPV infection (E6/E7 mRNAs) was also detected in microdissected SCJ cells. Early squamous atypia associated with the SCJ cells demonstrated in addition diffuse p16(ink4) immunoreactivity, elevated proliferative index, and rare L1 antigen positivity. We present for the first time direct evidence that normal-appearing SCJ cells can be infected by carcinogenic HPV. They initially express HPV E2 and their progression to SIL is heralded by an expanding metaplastic progeny with increased proliferation and p16(ink4) expression. Whether certain SCJs are more vulnerable than others to carcinogenic HPV genotypes and what variables determine transition to high-grade SIL remain unresolved, but the common event appears to be a vulnerable cell at the SCJ.
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http://dx.doi.org/10.1002/path.4533DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4457596PMC
July 2015

Hypoxia-inducible TAp73 supports tumorigenesis by regulating the angiogenic transcriptome.

Nat Cell Biol 2015 Apr 16;17(4):511-23. Epub 2015 Mar 16.

1] Division of Cellular &Molecular Research, Humphrey Oei Institute of Cancer Research, National Cancer Centre, Singapore 169610, Singapore [2] Cancer and Stem Cell Biology Program, Duke-NUS Graduate Medical School, Singapore 169857, Singapore [3] Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore.

The functional significance of the overexpression of unmutated TAp73, a homologue of the tumour suppressor p53, in multiple human cancers is unclear, but raises the possibility of unidentified roles in promoting tumorigenesis. We show here that TAp73 is stabilized by hypoxia, a condition highly prevalent in tumours, through HIF-1α-mediated repression of the ubiquitin ligase Siah1, which targets TAp73 for degradation. Consequently, TAp73-deficient tumours are less vascular and reduced in size, and conversely, TAp73 overexpression leads to increased vasculature. Moreover, we show that TAp73 is a critical regulator of the angiogenic transcriptome and is sufficient to directly activate the expression of several angiogenic genes.  Finally, expression of TAp73 positively correlates with these angiogenic genes in several human tumours, and the angiogenic gene signature is sufficient to segregate the TAp73(Hi)- from TAp73(Low)-expressing tumours. These data demonstrate a pro-angiogenic role for TAp73 in supporting tumorigenesis, providing a rationale for its overexpression in cancers.
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http://dx.doi.org/10.1038/ncb3130DOI Listing
April 2015

p63(+)Krt5(+) distal airway stem cells are essential for lung regeneration.

Nature 2015 Jan 12;517(7536):616-20. Epub 2014 Nov 12.

1] Genome Institute of Singapore, A-STAR, 138672 Singapore [2] The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut 06032, USA [3] Department of Medicine, National University Health System, 119228 Singapore.

Lung diseases such as chronic obstructive pulmonary disease and pulmonary fibrosis involve the progressive and inexorable destruction of oxygen exchange surfaces and airways, and have emerged as a leading cause of death worldwide. Mitigating therapies, aside from impractical organ transplantation, remain limited and the possibility of regenerative medicine has lacked empirical support. However, it is clinically known that patients who survive sudden, massive loss of lung tissue from necrotizing pneumonia or acute respiratory distress syndrome often recover full pulmonary function within six months. Correspondingly, we recently demonstrated lung regeneration in mice following H1N1 influenza virus infection, and linked distal airway stem cells expressing Trp63 (p63) and keratin 5, called DASC(p63/Krt5), to this process. Here we show that pre-existing, intrinsically committed DASC(p63/Krt5) undergo a proliferative expansion in response to influenza-induced lung damage, and assemble into nascent alveoli at sites of interstitial lung inflammation. We also show that the selective ablation of DASC(p63/Krt5) in vivo prevents this regeneration, leading to pre-fibrotic lesions and deficient oxygen exchange. Finally, we demonstrate that single DASC(p63/Krt5)-derived pedigrees differentiate to type I and type II pneumocytes as well as bronchiolar secretory cells following transplantation to infected lung and also minimize the structural consequences of endogenous stem cell loss on this process. The ability to propagate these cells in culture while maintaining their intrinsic lineage commitment suggests their potential in stem cell-based therapies for acute and chronic lung diseases.
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http://dx.doi.org/10.1038/nature13903DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7095488PMC
January 2015

The PAX2-null immunophenotype defines multiple lineages with common expression signatures in benign and neoplastic oviductal epithelium.

J Pathol 2014 Dec 30;234(4):478-87. Epub 2014 Sep 30.

Jackson Laboratory for Genomic Medicine, Farmington, CT, USA.

The oviducts contain high-grade serous cancer (HGSC) precursors (serous tubal intraepithelial neoplasia or STINs), which are γ-H2AX(p) - and TP53 mutation-positive. Although they express wild-type p53, secretory cell outgrowths (SCOUTs) are associated with older age and serous cancer; moreover, both STINs and SCOUTs share a loss of PAX2 expression (PAX2(n) ). We evaluated PAX2 expression in proliferating adult and embryonic oviductal cells, normal mucosa, SCOUTs, Walthard cell nests (WCNs), STINs, and HGSCs, and the expression of genes chosen empirically or from SCOUT expression arrays. Clones generated in vitro from embryonic gynaecological tract and adult Fallopian tube were Krt7(p) /PAX2(n) /EZH2(p) and underwent ciliated (PAX2(n) /EZH2(n) /FOXJ1(p) ) and basal (Krt7(n) /EZH2(n) /Krt5(p) ) differentiation. Similarly, non-ciliated cells in normal mucosa were PAX2(p) but became PAX2(n) in multi-layered epithelium undergoing ciliated or basal (WCN) cell differentiation. PAX2(n) SCOUTs fell into two groups: type 1 were secretory or secretory/ciliated with a 'tubal' phenotype and were ALDH1(n) and β-catenin(mem) (membraneous only). Type 2 displayed a columnar to pseudostratified (endometrioid) phenotype, with an EZH2(p) , ALDH1(p) , β-catenin(nc) (nuclear and cytoplasmic), stathmin(p) , LEF1(p) , RCN1(p) , and RUNX2(p) expression signature. STINs and HGSCs shared the type 1 immunophenotype of PAX2(n) , ALDH1(n) , β-catenin(mem) , but highly expressed EZH2(p) , LEF1(p) , RCN1(p) , and stathmin(p) . This study, for the first time, links PAX2(n) with proliferating fetal and adult oviductal cells undergoing basal and ciliated differentiation and shows that this expression state is maintained in SCOUTs, STINs, and HGSCs. All three entities can demonstrate a consistent perturbation of genes involved in potential tumour suppressor gene silencing (EZH2), transcriptional regulation (LEF1), regulation of differentiation (RUNX2), calcium binding (RCN1), and oncogenesis (stathmin). This shared expression signature between benign and neoplastic entities links normal progenitor cell expansion to abnormal and neoplastic outgrowth in the oviduct and exposes a common pathway that could be a target for early prevention.
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http://dx.doi.org/10.1002/path.4417DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4229427PMC
December 2014