John P Lydon

Baylor College of Medicine, Houston, Texas, United States

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Publications (177)1097.15 Total impact

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    ABSTRACT: Unlike cancers of related exocrine tissues such as the mammary and prostate gland, diagnosis and treatment of aggressive salivary gland malignancies have not markedly advanced in decades. Effective clinical management of malignant salivary gland cancers is undercut by our limited knowledge concerning the key molecular signals that underpin the etiopathogenesis of this rare and heterogeneous head and neck cancer. Without knowledge of the critical signals that drive salivary gland tumorigenesis, tumor vulnerabilities cannot be exploited that allow for targeted molecular therapies. This knowledge insufficiency is further exacerbated by a paucity of preclinical mouse models (as compared to other cancer fields) with which to both study salivary gland pathobiology and test novel intervention strategies. Using a mouse transgenic approach, we demonstrate that deregulation of the Receptor Activator of NFkB Ligand (RANKL)/RANK signaling axis results in rapid tumor development in all three major salivary glands. In line with its established role in other exocrine gland cancers (i.e., breast cancer), the RANKL/RANK signaling axis elicits an aggressive salivary gland tumor phenotype both at the histologic and molecular level. Despite the ability of this cytokine signaling axis to drive advanced stage disease within a short latency period, early blockade of RANKL/RANK signaling markedly attenuates the development of malignant salivary gland neoplasms. Together, our findings have uncovered a tumorigenic role for RANKL/RANK in the salivary gland and suggest that targeting this pathway may represent a novel therapeutic intervention approach in the prevention and/or treatment of this understudied head and neck cancer.
    PLoS ONE 06/2015; 10(6):e0128467. DOI:10.1371/journal.pone.0128467 · 3.53 Impact Factor
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    ABSTRACT: Progesterone (P4) and the synthetic glucocorticoid dexamethasone (Dex) inhibit luminal epithelial (LE) proliferation in neonatal mouse uteri. This study determined the roles of progesterone receptor and estrogen receptor 1 (PR and ESR1, respectively) in P4- and Dex-induced inhibition of LE proliferation using PR knockout (PRKO) and Esr1 knockout (Esr1KO) mice. Wild-type (WT), heterozygous and homozygous PRKO female pups were injected with vehicle, P4 (40 μg/g BW) or Dex (4 or 40 μg/g BW) on Postnatal Day 5, then 24 h later immunostained for markers of cell proliferation. In WT and heterozygous mice, P4 sharply reduced LE proliferation, and Dex produced dose-responsive decreases equaling those of P4 at the higher dose. Critically, although both doses of Dex similarly decreased proliferation compared to vehicle-treated PRKOs, treatment of PRKO pups with the high Dex dose (40 μg/g) did not inhibit LE as much as this Dex dose or P4 in WT mice. Stromal proliferation was stimulated by P4 in WT but not PRKO mice, and Dex did not alter stromal proliferation. Uteri of all genotypes strongly expressed glucocorticoid receptor (GR), demonstrating that impaired Dex effects in PRKOs did not reflect GR deficiency. Furthermore, inhibition of LE proliferation by Dex (40 μg/g) in Esr1KO mice was normal, so this process does not involve ESR1. In summary, inhibitory Dex effects on LE proliferation occur partially through non-PR mediated mechanisms, presumably GR, as indicated by Dex inhibition of LE proliferation in PRKOs. However, maximal inhibitory Dex effects on uterine LE proliferation are not seen in PRKO mice with even high Dex, indicating that maximal Dex effects in WT mice also involve PR. Copyright 2015 by The Society for the Study of Reproduction.
    Biology of Reproduction 04/2015; 92(5). DOI:10.1095/biolreprod.114.123463 · 3.45 Impact Factor
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    ABSTRACT: Intrauterine growth restriction (IUGR) affects up to 10% of pregnancies in Western societies. IUGR is a strong predictor of reduced short-term neonatal survival and impairs long-term health in children. Placental insufficiency is often associated with IUGR; however, the molecular mechanisms involved in the pathogenesis of placental insufficiency and IUGR are largely unknown. Here, we developed a mouse model of fetal-growth restriction and placental insufficiency that is induced by a midgestational stress challenge. Compared with control animals, pregnant dams subjected to gestational stress exhibited reduced progesterone levels and placental heme oxygenase 1 (Hmox1) expression and increased methylation at distinct regions of the placental Hmox1 promoter. These stress-triggered changes were accompanied by an altered CD8+ T cell response, as evidenced by a reduction of tolerogenic CD8+CD122+ T cells and an increase of cytotoxic CD8+ T cells. Using progesterone receptor- or Hmox1-deficient mice, we identified progesterone as an upstream modulator of placental Hmox1 expression. Supplementation of progesterone or depletion of CD8+ T cells revealed that progesterone suppresses CD8+ T cell cytotoxicity, whereas the generation of CD8+CD122+ T cells is supported by Hmox1 and ameliorates fetal-growth restriction in Hmox1 deficiency. These observations in mice could promote the identification of pregnancies at risk for IUGR and the generation of clinical interventional strategies.
    Journal of Clinical Investigation 03/2015; 125(4). DOI:10.1172/JCI68140 · 13.77 Impact Factor
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    ABSTRACT: Progesterone drives mammary stem and progenitor cell dynamics through paracrine mechanisms that are currently not well understood. Here, we demonstrate that CXCR4, the receptor for stromal-derived factor 1 (SDF-1; CXC12), is a crucial instructor of hormone-induced mammary stem and progenitor cell function. Progesterone elicits specific changes in the transcriptome of basal and luminal mammary epithelial populations, where CXCL12 and CXCR4 represent a putative ligand-receptor pair. In situ, CXCL12 localizes to progesterone-receptor-positive luminal cells, whereas CXCR4 is induced in both basal and luminal compartments in a progesterone-dependent manner. Pharmacological inhibition of CXCR4 signaling abrogates progesterone-directed expansion of basal (CD24(+)CD49f(hi)) and luminal (CD24(+)CD49f(lo)) subsets. This is accompanied by a marked reduction in CD49b(+)SCA-1(-) luminal progenitors, their functional capacity, and lobuloalveologenesis. These findings uncover CXCL12 and CXCR4 as novel paracrine effectors of hormone signaling in the adult mammary gland, and present a new avenue for potentially targeting progenitor cell growth and malignant transformation in breast cancer. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
    Stem Cell Reports 02/2015; DOI:10.1016/j.stemcr.2015.01.011
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    ABSTRACT: Rates of the most common gynecologic cancer, endometrioid adenocarcinoma (EAC), continue to rise, mirroring the global epidemic of obesity, a well-known EAC risk factor. Thus, identifying novel molecular targets to prevent and/or mitigate EAC is imperative. The prevalent Type 1 EAC commonly harbors loss of the tumor suppressor, Pten, leading to AKT activation. The major endoplasmic reticulum (ER) chaperone, GRP78, is a potent pro-survival protein to maintain ER homeostasis, and as a cell surface protein, is known to regulate the phosphatidylinositol 3-kinase (PI3K)/AKT pathway. To determine whether targeting GRP78 could suppress EAC development, we created a conditional knockout mouse model using progesterone receptor-Cre-recombinase to achieve Pten and Grp78 (cPten(f/f)Grp78(f/f)) deletion in the endometrial epithelium. Mice with a single Pten (cPten(f/f)) deletion developed well-differentiated EAC by 4 weeks. In contrast, no cPten(f/f)Grp78(f/f) mice developed EAC, even after more than 8 months of observation. Histologic examination of uteri from cPten(f/f)Grp78(f/f) mice also revealed no complex atypical hyperplasia, a well-established EAC precursor. These histologic observations among the cPten(f/f)Grp78(f/f) murine uteri also corresponded to abrogation of AKT activation within the endometrium. We further observed that GRP78 co-localized with activated AKT on the surface of EAC, thus providing an opportunity for therapeutic targeting. Consistent with previous findings that cell surface GRP78 is an upstream regulator of PI3K/AKT signaling, we show here that in vivo short-term systemic treatment with a highly specific monoclonal antibody against GRP78 suppressed AKT activation and increased apoptosis in the cPten(f/f) tumors. Collectively, these findings present GRP78-targeting therapy as an efficacious therapeutic option for EAC.Oncogene advance online publication, 16 February 2015; doi:10.1038/onc.2015.4.
    Oncogene 02/2015; DOI:10.1038/onc.2015.4 · 8.56 Impact Factor
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    ABSTRACT: Despite increasing evidence pointing to the essential involvement of transforming growth factor beta (TGFB) superfamily in reproduction, a definitive role of TGFB signaling in the uterus remains to be unveiled. In this study, we generated a gain-of-function mouse model harboring a constitutively active (CA) TGFB receptor 1 (TGFBR1), the expression of which was conditionally induced by the progesterone receptor (Pgr)-Cre recombinase. Overactivation of TGFB signaling was verified by enhanced phosphorylation of SMAD2 and increased expression of TGFB target genes in the uterus. TGFBR1 Pgr-Cre CA mice were sterile. Histological, cellular, and molecular analyses demonstrated that constitutive activation of TGFBR1 in the mouse uterus promoted formation of hypermuscled uteri. Accompanying this phenotype is the upregulation of a battery of smooth muscle genes in the uterus. Furthermore, TGFB ligands activated SMAD2/3 and stimulated the expression of a smooth muscle maker gene, alpha smooth muscle actin (ACTA2), in human uterine smooth muscle cells. Immunofluorescence microscopy identified a marked reduction of uterine glands in TGFBR1 Pgr-Cre CA mice within the endometrial compartment that contained myofibroblast-like cells. Thus, constitutively active TGFBR1 in the mouse uterus caused defects in uterine morphology and function, evidenced by abnormal myometrial structure, dramatically reduced uterine glands, and impaired uterine decidualization. These results underscore the importance of a precisely controlled TGFB signaling system in establishing a uterine microenvironment conducive to normal development and function. Copyright 2014 by The Society for the Study of Reproduction.
    Biology of Reproduction 12/2014; 92(2). DOI:10.1095/biolreprod.114.125146 · 3.45 Impact Factor
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    ABSTRACT: PTEN mutations are the most common genetic alterations in endometrial cancer. Loss of PTEN and subsequent AKT activation stimulate ERα-dependent pathways that play an important role in endometrial tumorigenesis. The major pathologic phenomenon of endometrial cancer is the loss of ovarian steroid hormone control over uterine epithelial cell proliferation and apoptosis. However, the precise mechanism of PTEN/AKT signaling in endometrial cancer remains poorly understood. The progesterone signaling mediator MIG-6 suppresses estrogen signaling and it has been implicated previously as a tumor suppressor in endometrial cancer. In this study, we show that MIG-6 also acts as a tumor suppressor in endometrial cancers associated with PTEN deficiency. Transgenic mice where Mig-6 was overexpressed in PR-expressing cells exhibited a relative reduction in uterine tumorigenesis caused by Pten deficiency. ERK1/2 was phosphorylated in uterine tumors and administration of an ERK1/2 inhibitor suppressed cancer progression in PRcre/+Ptenf/f mice. In clinical specimens of endometrial cancer, MIG-6 expression correlated inversely with ERK1/2 phosphorylation during progression. Taken together, our findings suggest that Mig-6 regulates ERK1/2 phosphorylation and that it is crucial for progression of PTEN-mutant endometrial cancers, providing a mechanistic rationale for the evaluation of ERK1/2 inhibitors as a therapeutic treatment in human endometrial cancer.
    Cancer Research 11/2014; 74(24). DOI:10.1158/0008-5472.CAN-14-0794 · 9.28 Impact Factor
  • Molecular Cancer Research 11/2014; 12(11 Supplement):A19-A19. DOI:10.1158/1557-3125.MODORG-A19 · 4.50 Impact Factor
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    ABSTRACT: Progesterone receptors (PRs) are phosphorylated on multiple sites, and a variety of roles for phosphorylation have been suggested by cell-based studies. Previous studies using PR null mice have shown that PR plays an important role in female fertility, regulation of uterine growth, the uterine decidualization response, and proliferation as well as ductal side branching and alveologenesis in the mammary gland. To study the role of PR phosphorylation in vivo, a mouse was engineered with homozygous replacement of PR with a PR serine-to-alanine mutation at amino acid 191. No overt phenotypes were observed in the mammary glands or uteri of PR S191A treated with progesterone (P4). In contrast, although PR S191A mice were fertile, litters were 19 smaller than wild type and the estrous cycle was lengthened slightly. Moreover, P4-dependent gene regulation in primary mammary epithelial cells (MECs) was altered in a gene-selective manner. MECs derived from wild-type and PR S191A mice were grown in a three-dimensional culture. Both formed acinar structures that were morphologically similar, and proliferation was stimulated equally by P4. However, P4 induction of receptor activator of nuclear factor-κB ligand and calcitonin was selectively reduced in S191A cultures. These differences were confirmed in freshly isolated MECs. Chromatin immunoprecipitation analysis showed that the binding of S191A PR to some of the receptor activator of nuclear factor-κB ligand enhancers and a calcitonin enhancer was substantially reduced. Thus, the elimination of a single phosphorylation site is sufficient to modulate PR activity in vivo. PR contains many phosphorylation sites, and the coordinate regulation of multiple sites is a potential mechanism for selective modulation of PR function.
    Molecular Endocrinology 10/2014; 28(12):me20141206. DOI:10.1210/me.2014-1206 · 4.20 Impact Factor
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    ABSTRACT: The p160/steroid receptor coactivator (SRC) family comprises three pleiotropic coregulators (SRC-1, -2, and -3; otherwise known as NCOA1, NCOA2, NCOA3), which modulate a wide spectrum of physiological responses and clinicopathologies. Such pleiotropy is achieved through their inherent structural complexity, which allows this coregulator class to control both nuclear receptor (NR) and non-NR signaling. As observed in other physiologic systems, members of the SRC family have recently been shown to play pivotal roles in uterine biology and pathobiology. In the murine uterus, SRC-1 is required to launch a full steroid hormone response, without which endometrial decidualization is markedly attenuated. From "dove-tailing" clinical and mouse studies, an isoform of SRC-1 was recently identified which promotes endometriosis by reprogramming endometrial cells to evade apoptosis and colonize as endometriotic lesions within the peritoneal cavity. The endometrium fails to decidualize without SRC-2, which accounts for the infertility phenotype exhibited by mice devoid of this coregulator. In related studies on human endometrial stromal cells (ESCs), SRC-2 was shown to act as a molecular "pace maker" of the glycolytic flux. This finding is significant as acceleration of the glycolytic flux provides the necessary bioenergy and biomolecules for ESCs to switch from quiescence to a proliferative phenotype, a critical underpinning in the decidual progression program. Though studies on uterine SRC-3 function are in their early stages, clinical studies provide tantalizing support for the proposal that SRC-3 is causally linked to endometrial hyperplasia as well as with endometrial pathologies in patients diagnosed with polycystic ovary syndrome. This proposal is now driving the development and application of innovative technologies particularly in the mouse to further understand the functional role of this elusive uterine coregulator in normal and abnormal physiologic contexts. Because dysregulation of this coregulator triad potentially presents a triple threat for increased risk of subfecundity, infertility, or endometrial disease, a clearer understanding of the individual and combinatorial roles of these coregulators in uterine function is urgently required. This minireview summarizes our current understanding of uterine SRC function, with a particular emphasis on the next critical questions that need to be addressed to ensure significant expansion of our knowledge of this underexplored field of uterine biology.
    Biology of Reproduction 10/2014; DOI:10.1095/biolreprod.114.125021 · 3.45 Impact Factor
  • Cancer Research 10/2014; 74(19 Supplement):60-60. DOI:10.1158/1538-7445.AM2014-60 · 9.28 Impact Factor
  • Cancer Research 10/2014; 74(19 Supplement):94-94. DOI:10.1158/1538-7445.AM2014-94 · 9.28 Impact Factor
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    ABSTRACT: Ovarian cancer is the deadliest gynecological malignancy in Western countries. Early detection, however, is hampered by the fact that the origin of ovarian cancer is still unclear. Knowing that in a high percentage of endometrioid ovarian cancers Wnt/β-catenin signaling is activated, and in view of the hypothesis that ovarian cancer may originate from the distal oviduct, we studied mice in which Wnt/β-catenin signaling was activated in Müllerian duct derived tissues. Conditional Apc knockout mice were used to study activation of Wnt/β-catenin signaling in Müllerian duct derived organs. These Pgr(Cre/+) ;Apc(ex15lox/lox) mice (n=44) were sacrificed at 10, 20, 40 and 80 weeks and uterus, oviduct, ovaries and surrounding fat tissues were assessed using immunohistochemistry. Using nuclear β-catenin staining, Wnt/β-catenin signaling activation was confirmed in the entire epithelium of the adult Müllerian duct (fimbriae, oviduct, endometrium), but was absent from ovarian surface epithelium cells (OSEs). Besides endometrial hyperplasia, in 87,2% of mice intraepithelial lesions of the distal oviduct were found, while OSEs remained unaffected. In addition, 62,5% of mice developed tumors in the distal and fimbrial part of the oviduct. In the ovaries, mainly at young age, in 16,3% of mice, simple epithelial cysts were noted, which developed further into endometrioid ovarian tumors, resembling human endometrioid ovarian cancer (27,9% of mice). Next to this, loco-regional growth in the utero-ovarian ligament was also shown. Here, for the first time, mutations (activation of Wnt/β-catenin) in the distal oviduct result in precursor lesions that develop into ovarian tumors resembling human endometrioid ovarian cancer. © 2014 Wiley Periodicals, Inc.
    International Journal of Cancer 09/2014; 135(5). DOI:10.1002/ijc.28746 · 5.01 Impact Factor
  • Fertility and Sterility 09/2014; 102(3):e128. DOI:10.1016/j.fertnstert.2014.07.439 · 4.30 Impact Factor
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    ABSTRACT: Type II endometrial carcinomas (ECs) are estrogen independent, poorly differentiated tumors that behave in an aggressive manner. As TP53 mutation and CDH1 inactivation occur in 80% of human endometrial type II carcinomas, we hypothesized that mouse uteri lacking both Trp53 and Cdh1 would exhibit a phenotype indicative of neoplastic transformation. Mice with conditional ablation of Cdh1 and Trp53 (Cdh1(d/d)Trp53(d/d)) clearly demonstrate architectural features characteristic of type II ECs, including focal areas of papillary differentiation, protruding cytoplasm into the lumen (hobnailing) and severe nuclear atypia at 6 months of age. Further, Cdh1(d/d)Trp53(d/d) tumors in 12-month-old mice were highly aggressive, and metastasized to nearby and distant organs within the peritoneal cavity, such as abdominal lymph nodes, mesentery and peri-intestinal adipose tissues, demonstrating that tumorigenesis in this model proceeds through the universally recognized morphological intermediates associated with type II endometrial neoplasia. We also observed abundant cell proliferation and complex angiogenesis in the uteri of Cdh1(d/d)Trp53(d/d) mice. Our microarray analysis found that most of the genes differentially regulated in the uteri of Cdh1(d/d)Trp53(d/d) mice were involved in inflammatory responses. CD163 and Arg1, markers for tumor-associated macrophages, were also detected and increased in the uteri of Cdh1(d/d)Trp53(d/d) mice, suggesting that an inflammatory tumor microenvironment with immune cell recruitment is augmenting tumor development in Cdh1(d/d)Trp53(d/d) uteri. Further, inflammatory mediators secreted from CDH1-negative, TP53 mutant endometrial cancer cells induced normal macrophages to express inflammatory-related genes through activation of nuclear factor-κB signaling. These results indicate that absence of CDH1 and TP53 in endometrial cells initiates chronic inflammation, promotes tumor microenvironment development following the recruitment of macrophages and promotes aggressive ECs.Oncogene advance online publication, 7 July 2014; doi:10.1038/onc.2014.193.
    Oncogene 07/2014; 34(19). DOI:10.1038/onc.2014.193 · 8.56 Impact Factor
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    ABSTRACT: Coordinated uterine-embryonic axis formation and decidual remodeling are hallmarks of mammalian post-implantation embryo development. Embryonic-uterine orientation is determined at initial implantation and synchronized with decidual development. However, the molecular mechanisms controlling these events remain elusive despite its discovery a long time ago. In the present study, we found that uterine-specific deletion of Rbpj, the nuclear transducer of Notch signaling, resulted in abnormal embryonic-uterine orientation and decidual patterning at post-implantation stages, leading to substantial embryo loss. We further revealed that prior to embryo attachment, Rbpj confers on-time uterine lumen shape transformation via physically interacting with uterine estrogen receptor (ERα) in a Notch pathway-independent manner, which is essential for the initial establishment of embryo orientation in alignment with uterine axis. While at post-implantation stages, Rbpj directly regulates the expression of uterine matrix metalloproteinase in a Notch pathway-dependent manner, which is required for normal post-implantation decidual remodeling. These results demonstrate that uterine Rbpj is essential for normal embryo development via instructing the initial embryonic-uterine orientation and ensuring normal decidual patterning in a stage-specific manner. Our data also substantiate the concept that normal mammalian embryonic-uterine orientation requires proper guidance from developmentally controlled uterine signaling.Cell Research advance online publication 27 June 2014; doi:10.1038/cr.2014.82.
    Cell Research 06/2014; DOI:10.1038/cr.2014.82 · 11.98 Impact Factor
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    ABSTRACT: As pleiotropic coregulators, members of the p160/steroid receptor coactivator (SRC) family control a broad spectrum of transcriptional responses that underpin a diverse array of physiological and pathophysiological processes. Because of their potent coregulator properties, strict controls on SRC expression levels are required to maintain normal tissue functionality. Accordingly, an unwarranted increase in the cellular levels of SRC members has been causally linked to the initiation and/or progression of a number of clinical disorders. Although knockout mouse models have underscored the critical non-redundant roles for each SRC member in vivo, there are surprisingly few mouse models that have been engineered to overexpress SRCs. This deficiency is significant since SRC involvement in many of these disorders is based on unscheduled increases in the levels (rather than the absence) of SRC expression. To address this deficiency, we used recent mouse technology that allows for the targeted expression of human SRC-2 in cells which express the progesterone receptor. Through cre-loxP recombination driven by the endogenous progesterone receptor promoter, a marked elevation in expression levels of human SRC-2 was achieved in endometrial cells that are positive for the progesterone receptor. As a result of this increase in coregulator expression, female mice are severely subfertile due to a dysfunctional uterus, which exhibits a hypersensitivity to estrogen exposure. Our findings strongly support the proposal from clinical observations that increased levels of SRC-2 are causal for a number of endometrial disorders which compromise fertility. Future studies will use this mouse model to decipher the molecular mechanisms that underpin the endometrial defect. We believe such mechanistic insight may provide new molecular descriptors for diagnosis, prognosis, and/or therapy in the clinical management of female infertility.
    PLoS ONE 06/2014; 9(6):e98664. DOI:10.1371/journal.pone.0098664 · 3.53 Impact Factor
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    ABSTRACT: Infertility and adverse gynecological outcomes such as preeclampsia and miscarriage represent significant female reproductive health concerns. The spatiotemporal expression of growth factors indicates that they play an important role in pregnancy. The goal of this study is to define the role of the ERBB family of growth factor receptors in endometrial function. Using conditional ablation in mice and siRNA in primary human endometrial stromal cells, we identified the epidermal growth factor receptor (Egfr) to be critical for endometrial function during early pregnancy. While ablation of Her2 or Erbb3 led to only a modest reduction in litter size, mice lacking Egfr expression are severely subfertile. Pregnancy demise occurred shortly after blastocyst implantation due to defects in decidualization including decreased proliferation, cell survival, differentiation and target gene expression. To place Egfr in a genetic regulatory hierarchy, transcriptome analyses was used to compare the gene signatures from mice with conditional ablation of Egfr, wingless-related MMTV integration site 4 (Wnt4) or boneless morphogenic protein 2 (Bmp2); revealing that not only are Bmp2 and Wnt4 key downstream effectors of Egfr, but they also regulate distinct physiological functions. In primary human endometrial stromal cells, marker gene expression, a novel high content image-based approach and phosphokinase array analysis were used to demonstrate that EGFR is a critical regulator of human decidualization. Furthermore, inhibition of EGFR signaling intermediaries WNK1 and AKT1S1, members identified in the kinase array and previously unreported to play a role in the endometrium, also attenuate decidualization. These results demonstrate that EGFR plays an integral role in establishing the cellular context necessary for successful pregnancy via the activation of intricate signaling and transcriptional networks, thereby providing valuable insight into potential therapeutic targets.
    PLoS Genetics 06/2014; 10(6):e1004451. DOI:10.1371/journal.pgen.1004451 · 8.52 Impact Factor
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    ABSTRACT: Breast cancer (BCa) molecular subtypes include luminal A, luminal B, normal-like, HER-2–enriched, and basal-like tumors, among which luminal B and basal-like cancers are highly aggressive. Biochemical pathways associated with patient survival or treatment response in these more aggressive subtypes are not well understood. With the limited availability of pathologically verified clinical specimens, cell line models are routinely used for pathway-centric studies. We measured the metabolome of luminal and basal-like BCa cell lines using mass spectrometry, linked metabolites to biochemical pathways using Gene Set Analysis, and developed a novel rank-based method to select pathways on the basis of their enrichment in patient-derived omics data sets and prognostic relevance. Key mediators of the pathway were then characterized for their role in disease progression. Pyrimidine metabolism was altered in luminal versus basal BCa, whereas the combined expression of its associated genes or expression of one key gene, ribonucleotide reductase subunit M2 (RRM2) alone, associated significantly with decreased survival across all BCa subtypes, as well as in luminal patients resistant to tamoxifen. Increased RRM2 expression in tamoxifen-resistant patients was verified using tissue microarrays, whereas the metabolic products of RRM2 were higher in tamoxifen-resistant cells and in xenograft tumors. Both genetic and pharmacological inhibition of this key enzyme in tamoxifen-resistant cells significantly decreased proliferation, reduced expression of cell cycle genes, and sensitized the cells to tamoxifen treatment. Our study suggests for evaluating RRM2-associated metabolites as noninvasive markers for tamoxifen resistance and its pharmacological inhibition as a novel approach to overcome tamoxifen resistance in BCa.
    Neoplasia (New York, N.Y.) 05/2014; 16(5):390–402. DOI:10.1016/j.neo.2014.05.007 · 5.40 Impact Factor
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    ABSTRACT: The pathogenesis of endometriosis remains unclear, and relatively little is known about the mechanisms that promote establishment and survival of the disease. Previously, we demonstrated that AKT activity was increased in endometriosis tissues and cells from ovarian endometriomas and that this increase promoted cell survival as well as decreased levels of progesterone receptor. The objective of this study was to demonstrate a role for AKT in the establishment of ectopic lesions. First, a dose-dependent inhibition of AKT in stromal cells from human ovarian endometriomas (OSIS) as well as endometrial stromal cells from disease-free patients (ESC) with the allosteric AKT inhibitor MK-2206 was demonstrated by decreased levels of phosphorylated (p)(Ser473)-AKT. Levels of the AKT target protein, p(Ser256)-FOXO1 were increased in OSIS cells, which decreased with MK-2206 treatment, whereas levels of p(Ser9)-GSK3β did not change in response to MK-2206. Although MK-2206 decreased viability of both OSIS and ESC in a dose-dependent manner, proliferation of OSIS cells was differentially decreased significantly compared with ESC. Next, the role of hyperactive AKT in the establishment of ectopic lesions was studied using the bigenic, PR(cre/+) Pten(f/+) heterozygous mouse. Autologous implantation of uterine tissues was performed in these mice. After 4 weeks, an average of 4 ± 0.33 lesions per Pten(f/+) mouse and 7.5 ± 0.43 lesions in the PR(cre/+)Pten(f/+) mouse were found. Histological examination of the lesions showed endometrial tissue-like morphology, which was similar in both the Pten(f/+) and PR(cre/+)Pten(f/+) mice. Treatment of mice with MK-2206 resulted in a significantly decreased number of lesions established. Immunohistochemical staining of ectopic lesions revealed decreased p(Ser473)-AKT and the proliferation marker Ki67 from MK-2206-treated mice compared with vehicle-treated mice. Furthermore, levels of FOXO1 and progesterone receptor increased in lesions of mice receiving MK-2206. These results demonstrate that heightened AKT activity plays an active role in the establishment of ectopic endometrial tissues.
    Endocrinology 02/2014; 155(5):en20131951. DOI:10.1210/en.2013-1951 · 4.64 Impact Factor

Publication Stats

9k Citations
1,097.15 Total Impact Points

Institutions

  • 1991–2015
    • Baylor College of Medicine
      • Department of Molecular & Cellular Biology
      Houston, Texas, United States
  • 2006–2014
    • Molecular and Cellular Biology Program
      Seattle, Washington, United States
    • Institut Clinique de la Souris
      Illkirch, Alsace, France
  • 2007
    • Texas A&M University System Health Science Center
      • Texas A&M Health Science Center
      Bryan, Texas, United States
  • 2000
    • University of California, San Francisco
      • Department of Anatomy
      San Francisco, CA, United States
  • 1996
    • National Institutes of Health
      • Section on Developmental Biology
      Bethesda, MD, United States