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* Context.--Molecular analysis of poorly differentiated/ undifferentiated sinonasal neoplasms has resulted in identification of a growing number of genetically defined tumors. SMARCA4-deficient sinonasal carcinoma is one such recently described entity that emerged from within sinonasal undifferentiated carcinoma (SNUC), neuroendocrine carcinoma (NEC), and teratocarcinosarcoma (TCS). Objective.--To identify SMARCA4-deficient sinonasal carcinomas from a large institutional cohort of poorly differentiated/undifferentiated carcinomas and evaluate their clinicopathologic features. Design.--SMARCA4/BRG1 immunohistochemistry was performed on all tumors diagnosed as SNUC, poorly differentiated carcinoma, NEC, and TCS during a 12-year period. SMARCA2/BRM and INSM1 immunostaining was performed in SMARCA4-deficient cases. Results.--Twelve SMARCA4-deficient sinonasal carcinomas were identified among 299 cases. Morphologically, 5 cases were large cell NEC, 2 cases were small cell NEC, and 5 were TCS. SMARCA4 loss was diffuse and complete in 10 cases, while 2 cases showed focal retention. Most cases showed diffuse cytokeratin staining accompanied by weak, usually focal staining for chromogranin and synaptophysin. INSM-1 showed negativity in most cases. All cases showed retained SMARCA2 expression. IDH1/2 mutation was absent in all cases analyzed. Four of 7 patients died of disease, and aggressive multimodality treatment provided better outcome. Conclusions.--SMARCA4-deficient sinonasal carcinomas are morphologically akin to sinonasal poorly differentiated NECs and TCS, display cytokeratin positivity and only focal staining for neuroendocrine markers, and have aggressive biological behavior. Inclusion of SMARCA4 in the immunohistochemical panel for diagnostic workup of all sinonasal NEC and TCS phenotypes will facilitate their early recognition. Comprehensive germline and somatic mutational analyses of these tumors are necessary for further insights into their molecular pathogenesis. (Arch Pathol Lab Med. 2022;146:1122-1130; doi: 10.5858/arpa.2021-0001-OA), The sinonasal tract harbors a diverse spectrum of high-grade neoplasms, many of which have considerable overlapping morphologic features owing to their poorly differentiated or undifferentiated appearance. (1,2) Some of these [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2010.04.005 Byline: Christopher M. Baker (a), Annemieke Verstuyf (b), Kim B. Jensen (c), Fiona M. Watt (a)(c) Keywords: Wnt; Vitamin D receptor; Stem cells; Differentiation; Epidermis; Niche Abstract: Wnt signalling is required for hair follicle development and for the growth phase (anagen) of postnatal follicles. When the pathway is activated at high levels in adult mouse epidermis, ectopic follicles form from existing follicles, interfollicular epidermis (IFE) and sebaceous glands, revealing a remarkable ability of the tissue to be reprogrammed. To compare the competence of different epidermal cell populations to form ectopic follicles, we expressed a 4-hydroxy-tamoxifen (4OHT) inducible, stabilised [beta]-catenin transgene ([DELTA]N[beta]-cateninER) under the control of two different promoters. We targeted the reservoir of stem cells in the hair follicle bulge via the keratin 15 (K15) promoter and targeted the sebaceous glands and base of the follicle (bulb) with a truncated K5 promoter ([DELTA]K5). No ectopic follicles formed in the IFE in either model, establishing the autonomy of the IFE stem cell compartment in undamaged epidermis. Activation of [beta]-catenin in the bulge stimulated proliferation and bulge expansion. Existing hair follicles entered anagen, but no ectopic follicles formed. [DELTA]K5[DELTA]N[beta]-cateninER expressing hair follicles also entered anagen on 4OHT treatment. In addition, a subpopulation of cells at the base of the sebaceous gland readily formed ectopic follicles, resulting in complete and reversible conversion of sebaceous glands into hair follicles. Combined activation of [beta]-catenin and the vitamin D receptor enhanced differentiation of sebaceous gland-derived hair follicles and stimulated ectopic follicle formation in the hair follicle bulb, but not in the bulge. Our results suggest that the bulge and sebaceous gland are, respectively, non-permissive and permissive niches for Wnt induced hair follicle differentiation. Author Affiliation: (a) CRUK Cambridge Research Institute, Li Ka Shing Centre, Robinson Way, Cambridge CB2 0RE, UK (b) Laboratory of Experimental Medicine and Endocrinology, KULeuven, Herestraat 49 bus 902, 3000 Leuven, Belgium (c) Wellcome Trust Centre for Stem Cell Research, Tennis Court Road, Cambridge CB2 1QR, UK Article History: Received 4 February 2010; Revised 24 March 2010; Accepted 8 April 2010

We report isotopic data ([delta][sup.2]H, [delta][sup.18]O n = 196; [delta][sup.13]C, [delta][sup.15]N n = 142; [delta][sup.34]S n = 85) from human hair and drinking water ([delta][sup.2]H, [delta][sup.18]O n = 67) collected across China, India, Mongolia, and Pakistan. Hair isotope ratios reflected the large environmental isotopic gradients and dietary differences. Geographic information was recorded in H and 0 and to a lesser extent, S isotopes. H and 0 data were entered into a recently developed model describing the relationship between the H and 0 isotope composition of human hair and drinking water in modern USA and pre-globalized populations. This has anthropological and forensic applications including reconstructing environment and diet in modern and ancient human hair. However, it has not been applied to a modern population outside of the USA, where we expect different diet. Relationships between H and 0 isotope ratios in drinking water and hair of modern human populations in Asia were different to both modern USA and pre-globalized populations. However, the Asian dataset was closer to the modern USA than to pre-globalized populations. Model parameters suggested slightly higher consumption of locally produced foods in our sampled population than modern USA residents, but lower than pre-globalized populations. The degree of in vivo amino acid synthesis was comparable to both the modern USA and pre-globalized populations. C isotope ratios reflected the predominantly C3-based regional agriculture and C4 consumption in northern China. C, N, and S isotope ratios supported marine food consumption in some coastal locales. N isotope ratios suggested a relatively low consumption of animal-derived products compared to western populations. Am J Phys Anthropol 141:440-451, 2010. KEY WORDS hair keratin; stable isotope; Asia DOI 10.1002/ajpa.21162

Keratin intermediate filament proteins form cytoskeletal scaffolds in epithelia, the disruption of which affects cytoarchitecture, cell growth, survival, and organelle transport. However, owing to redundancy, the global function of keratins has not been defined in full. Using a targeted gene deletion strategy, we generated transgenic mice lacking the entire keratin multiprotein family. In this study, we report that without keratins, embryonic epithelia suffer no cytolysis and maintain apical polarity but display mislocalized desmosomes. All keratin-null embryos die from severe growth retardation at embryonic day 9.5. We find that GLUT1 and -3 are mislocalized from the apical plasma membrane in embryonic epithelia, which subsequently activates the energy sensor adenosine monophosphate kinase (AMPK). Analysis of the mammalian target of rapamycin (mTOR) pathway reveals that AMPK induction activates Raptor, repressing protein biosynthesis through mTORC1 's downstream targets S6 kinase and 4E-binding protein 1. Our findings demonstrate a novel keratin function upstream of mTOR signaling via GLUT localization and have implications for pathomechanisms and therapy approaches for keratin disorders and the analysis of other gene families. doi 10.1083/jcb.200906094

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2009.07.028 Byline: Yu Chen (a), Eric C. Carlson (b), Zhi-Yi Chen (c), Anne Hamik (d), Mukesh K. Jain (d), Sally L. Dunwoodie (e)(f), Yu-Chung Yang (a) Keywords: Cited2; Corneal epithelial cell; K12 expression; Wound healing Abstract: Cited2 is an important transcriptional cofactor involved in multiple organ development. Gene profile analysis has identified Cited2 as one of the transcription factors expressed at high levels in adult mouse cornea. To address the function of Cited2 in corneal morphogenesis, we deleted Cited2 in surface ectoderm derived ocular structures including cornea by crossing Cited2-floxed mice with Le-Cre transgenic mice. Cited2.sup.flox/flox;Le-Cre.sup.+ eyes invariably displayed corneal opacity and developed spontaneous corneal neovascularization at older age. Fewer layers of corneal epithelial cells and the absence of cytokeratin 12 (K12) expression featured Cited2 deficient postnatal and adult eyes. Cited2 deficient cornea exhibited impaired healing in response to corneal epithelial debridement by manifesting abnormal histology, lack of K12 expression and corneal neovascularization. Moreover, mechanistic studies suggest that Cited2 may play a role in corneal morphogenesis in part through modulating the expression of Pax6 and Klf4. Collectively, these findings demonstrate a novel function of Cited2 in postnatal corneal morphogenesis and maintenance. Our study will help better understand the molecular mechanisms involved in corneal biology, and more importantly, it may provide a valuable animal model for testing therapeutics in the treatment of corneal disorders, especially blindness as a result of corneal epithelial cell deficiency. Author Affiliation: (a) Department of Biochemistry and Cancer Center, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, W424, Cleveland, OH 44106, USA (b) Department of Ophthalmology, Case Western Reserve University, Cleveland, OH 44106, USA (c) Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA (d) Case Cardiovascular Research Institute and University Hospitals, Harrington-McLaughlin Heart & Vascular Institute, Department of Medicine, Case Western Reserve University School of Medicine, OH 44106, USA (e) Developmental Biology Division, The Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW 2010, Australia (f) St Vincent's Clinical School, University of New South Wales, Kensington, NSW, Australia Article History: Received 5 March 2009; Revised 16 July 2009; Accepted 17 July 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2009.04.021 Byline: Martyn T. Cobourne (a), Guilherme M. Xavier (b), Michael Depew (b), Louise Hagan (a), Jane Sealby (c), Zoe Webster (c), Paul T. Sharpe (b)(d) Keywords: Sonic hedgehog; Nevoid basal cell carcinoma syndrome; Cleft palate; Hypertelorism; Hypodontia; Craniofacial development; Ptch1; Gli1; Transgenic; Keratin-14 Abstract: Nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant or spontaneous disorder characterized by multiple cutaneous basal cell carcinomas, odontogenic keratocysts, skeletal anomalies and facial dysmorphology, including cleft lip and palate. Causative mutations for NBCCS occur in the PTCH1 gene on chromosome 9q22.3-q31, which encodes the principle receptor for the Hedgehog signalling pathway. We have investigated the molecular basis of craniofacial defects seen in NBCCS using a transgenic mouse model expressing Shh in basal epithelium under a Keratin-14 promoter. These mice have an absence of flat bones within the skull vault, hypertelorism, open-bite malocclusion, cleft palate and arrested tooth development. Significantly, increased Hedgehog signal transduction in these mice can influence cell fate within the craniofacial region. In medial edge epithelium of the palate, Shh activity prevents apoptosis and subsequent palatal shelf fusion. In contrast, high levels of Shh in odontogenic epithelium arrests tooth development at the bud stage, secondary to a lack of cell proliferation in this region. These findings illustrate the importance of appropriately regulated Hedgehog signalling during early craniofacial development and demonstrate that oro-facial clefting and hypodontia seen in NBCCS can occur as a direct consequence of increased Shh signal activity within embryonic epithelial tissues. Author Affiliation: (a) Department of Craniofacial Development and Orthodontics, Dental Institute, King's College London, Floor 27, Guy's Hospital, London SE1 9RT, UK (b) Department of Craniofacial Development, Dental Institute, King's College London, Floor 27, Guy's Hospital, London SE19RT, UK (c) Embryonic Stem Cell Facility, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital, London W12 0NN, UK (d) Biomedical Research Centre, Guy's and St Thomas' NHS Foundation Trust, Guy's Hospital, UK Article History: Received 19 November 2008; Revised 16 April 2009; Accepted 20 April 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2009.02.032 Byline: Yeon Sook Choi, Rumela Chakrabarti, Rosalba Escamilla-Hernandez, Satrajit Sinha Keywords: Elf5; Conditional knockout; Alveologenesis; Stat5; Transcription Abbreviations: AQP5, aquaporin 5; Cldn7, claudin 7; Elf5, E74-like factor 5; ER[alpha], estrogen receptor alpha; ES, embryonic stem; ESE, epithelium specific Ets; Ets, E twenty-six; Id2, inhibitor of DNA binding 2; IKK[alpha], inhibitor of kappa B kinase alpha; Jak2, janus kinase 2; K14, cytokeratin 14; K18, cytokeratin 18; Lmo4, LIM domain only 4; MMTV, mouse mammary tumor virus; Muc-1, mucin 1; NKCC1, Na-K-Cl cotransporter 1; Npt2b, Na-Pi type IIb cotransporter; PGK-neo, phosphoglycerate kinase-neomycin; PR, progesterone receptor; PrlR, prolactin receptor; SOCS, suppressor of cytokine signaling; Stat5, signal transducer and activator of transcription 5; p-Stat5, phosphorylated Stat5; TEB, terminal end buds; Wap, whey acidic protein Abstract: The transcription factor Elf5 plays an important role in mammary gland development. However, because of the embryonic lethality of Elf5 straight knockout mice, prior studies have been limited to experiments with Elf5 haploinsufficient animals, overexpression systems or transplants. Here, we have utilized K14-Cre to generate mammary-gland specific Elf5 conditional knockout mice. During pregnancy, Elf5-null mammary epithelium completely failed to initiate alveologenesis, and a characteristic of virgin ductal epithelial cells persisted postpartum. We demonstrate that the loss of Elf5 leads to the absence of alveolar secretory markers confirming previous published data. Interestingly, the developmental block due to a lack of Elf5 could not be restored by multiple gestations. Elf5-null mammary epithelial cells also display disorganized cell structures as evident by altered cell polarities, which might be the cause for collapsed lumina. We observe reduced levels of Stat5 and attenuated Stat5 activity as measured by p-Stat5 levels both in Elf5-null mammary glands as well as cultured mammary epithelial cells. This data suggests that the failure of alveolar and lactogenic differentiation due to the loss of Elf5 is mediated in part due to impaired Stat5 activity. In support of this hypothesis, we show by ChIP experiments that Stat5a promoter contains a conserved Elf5-binding site that is occupied by Elf5 in mammary glands. Mammary epithelia lacking Elf5 exhibited downregulation of several other critical genes involved in alveologenesis, suggesting Elf5 as a master regulator in alveolar development. We propose a model for Elf5-mediated alveolar development, in which Elf5 regulates the expression of key mediators of the PrlR/Jak2/Stat5 signaling pathway. Author Affiliation: Department of Biochemistry, State University of New York at Buffalo, Center of Excellence in Bioinformatics and Life Sciences, 701 Ellicott Street, Buffalo, NY 14203, USA Article History: Received 29 July 2008; Revised 20 February 2009; Accepted 20 February 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2008.08.016 Byline: Yan Zhang (a), Daniel Burgess (a), Paul A. Overbeek (b), Venkatesh Govindarajan (a) Keywords: Lens; Ablation; Cornea; Diphtheria toxin; Iris; Ciliary body; Transgenic mice; Retina; Lacrimal glands; Harderian glands Abstract: The lens in the vertebrate eye has been shown to be critical for proper differentiation of the surrounding ocular tissues including the cornea, iris and ciliary body. In mice, previous investigators have assayed the consequences of molecular ablation of the lens. However, in these studies, lens ablation was initiated (and completed) after the cornea, retina, iris and ciliary body had initiated their differentiation programs thereby precluding analysis of the early role of the lens in fate determination of these tissues. In the present study, we have ablated the lens precursor cells of the surface ectoderm by generation of transgenic mice that express an attenuated version of diphtheria toxin (Tox176) linked to a modified Pax6 promoter that is active in the lens ectodermal precursors. In these mice, lens precursor cells fail to express Sox2, Prox1 and [alpha]A-crystallin and die before the formation of a lens placode. The Tox176 mice also showed profound alterations in the corneal differentiation program. The corneal epithelium displayed histological features of the skin, and expressed markers of skin differentiation such as Keratin 1 and 10 instead of Keratin 12, a marker of corneal epithelial differentiation. In the Tox176 mice, in the absence of the lens, extensive folding of the retina was seen. However, differentiation of the major cell types in the retina including the ganglion, amacrine, bipolar and horizontal cells was not affected. Unexpectedly, ectopic placement of the retinal pigmented epithelium was seen between the folds of the retina. Initial specification of the presumptive ciliary body and iris at the anterior margins of the retina was not altered in the Tox176 mice but their subsequent differentiation was blocked. Lacrimal and Harderian glands, which are derived from the Pax6-expressing surface ectodermal precursors, also failed to differentiate. These results suggest that, in mice, specification of the retina, ciliary body and iris occurs at the very outset of eye development and independent of the lens. In addition, our results also suggest that the lens cells of the surface ectoderm may be critical for the proper differentiation of the corneal epithelium. Author Affiliation: (a) Department of Surgery, 254 Criss III, 2500 California Plaza, Creighton University, Omaha, NE 68178, USA (b) Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA Article History: Received 14 April 2008; Revised 25 July 2008; Accepted 14 August 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2005.11.009 Byline: Xi-De Wang (a), Ching Ching Leow (a), Jiping Zha (b), Zhijun Tang (c), Zora Modrusan (a), Freddy Radtke (d), Michel Aguet (e), Frederic J. de Sauvage (a), Wei-Qiang Gao (a) Keywords: Notch; Prostate development; Cell proliferation; Cell differentiation; Mouse models; Prostate cancer Abbreviations: BPH, benign prostatic hyperplasia; CK, cytokeratin; Cre, Cre-recombinase; DAPI, 4,6-diamidino-2-phenylindole Abstract: Notch pathway is crucial for stem/progenitor cell maintenance, growth and differentiation in a variety of tissues. Using a transgenic cell ablation approach, we found in our previous study that cells expressing Notch1 are crucial for prostate early development and re-growth. Here, we further define the role of Notch signaling in regulating prostatic epithelial cell growth and differentiation using biochemical and genetic approaches in ex vivo or in vivo systems. Treatment of developing prostate grown in culture with inhibitors of gamma-secretase/presenilin, which is required for Notch cleavage and activation, caused a robust increase in proliferation of epithelial cells co-expressing cytokeratin 8 and 14, lack of luminal/basal layer segregation and dramatically reduced branching morphogenesis. Using conditional Notch1 gene deletion mouse models, we found that inactivation of Notch1 signaling resulted in profound prostatic alterations, including increased tufting, bridging and enhanced epithelial proliferation. Cells within these lesions co-expressed both luminal and basal cell markers, a feature of prostatic epithelial cells in predifferentiation developmental stages. Microarray analysis revealed that the gene expression in a number of genetic networks was altered following Notch1 gene deletion in prostate. Furthermore, expression of Notch1 and its effector Hey-1 gene in human prostate adenocarcinomas were found significantly down-regulated compared to normal control tissues. Taken together, these data suggest that Notch signaling is critical for normal cell proliferation and differentiation in the prostate, and deregulation of this pathway may facilitate prostatic tumorigenesis. Author Affiliation: (a) Department of Molecular Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA (b) Department of Pathology, Genentech, Inc., South San Francisco, CA 94080, USA (c) Department of Bioinformatics, Genentech, Inc., South San Francisco, CA 94080, USA (d) Ludwig Institute for Cancer Research, Lausanne Branch, University of Lausanne, 1066 Epalinges, Switzerland (e) Swiss Institute of Experimental Cancer Research, 1066 Epalinges, Switzerland Article History: Received 21 September 2005; Revised 5 November 2005; Accepted 7 November 2005

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2005.04.042 Byline: Wei-Yuan Yu, Jonathan M.W. Slack, David Tosh Keywords: Oesophagus; Epithelium; Cytokeratin; Transdifferentiation; DNA methylation Abstract: The mouse embryonic oesophagus is initially lined with a simple columnar epithelial layer which changes during the course of development to a stratified squamous tissue. To study the mechanism of this transition, we developed an in vitro model, based on oesophageal explants isolated from E11.5d mouse embryos, which fully recapitulates the normal in vivo development. In this system, the columnar epithelial markers cytokeratins 8 and 18 (K8, 18) were strongly expressed at the beginning of the culture period and decreased in the basal layer of the epithelium at around 5 days of culture. Expression of K8 + 18 persisted in the suprabasal layers of the stratified epithelium for several more days. In contrast, the stratified squamous epithelial marker cytokeratin 14 (K14) was absent at the beginning, and cells expressing it progressively appeared within the basal layer from day 5 to day 9 of culture. The two possible mechanisms for the change are (1) a direct conversion of columnar cells to the basal layer cells of the squamous epithelium; (2) an overgrowth of columnar by squamous cells. Our results show that the first mechanism is operative. Firstly, co-staining for K8 and K14 demonstrates that some cells express both markers during the transition period. Secondly, after electroporation of a construct containing the K14 promoter driving nuclear GFP into the epithelium of E15.5 oesophagus, some cells expressed both K8 and GFP. Thirdly, there is no preferential loss of the columnar cells by apoptosis. Fourthly, inhibitors of apoptosis do not affect the process. Finally, inhibitors of cell division do not affect the process. In terms of the molecular mechanism, inhibitor studies suggest that de novo DNA methylation is required for the loss of the K8 expression but not for the acquisition of the K14 expression. The results show that, in normal development, the squamous epithelium arises from the columnar epithelium by a direct conversion process. Author Affiliation: Department of Biology and Biochemistry, Centre for Regenerative Medicine, University of Bath, Claverton Down, Bath BA2 7AY, UK Article History: Received 7 January 2005; Revised 25 April 2005; Accepted 27 April 2005

Context.--The pioneering works on molecular classification (MC) by Perou and Sorlie et al in the early 2000s using global gene expression profiling identified 5 intrinsic subtypes of invasive breast cancers (IBCs): luminal A, luminal B, normal breast-like, HER2-enriched, and basal-like subtypes, each unique in incidence, survival, and response to therapy. Because the application of gene expression profiling in daily practice is not economical or practical at the present time, many investigators have studied the use of immunohistochemical (IHC) surrogates as a substitute for determining the MC of IBC. Objective.--To discuss the continuing efforts that have been made to develop clinically significant and readily available IHC surrogates for the MC of IBC. Data Sources.--Data were obtained from pertinent peer-reviewed English-language literature. Conclusions.--The most commonly used IHC surrogates are estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2), dividing IBC into luminal, HER2, and triple-negative subtypes. The addition of Ki-67, cytokeratin 5, and epidermal growth factor receptor (EGFR) separates luminal B from luminal A subtypes, and basal-like subtype from triple-negative breast cancer. More recently, biomarkers such as androgen receptor and p53 have been shown to further stratify these molecular subtypes. Although many studies of IHC-based MC have shown clinical significance similar to gene expression profiling-defined MC, its critical limitations are: (1) a lack of standardization in terminology, (2) a lack of standardization in biomarkers used for each subtype, and (3) the lack of a uniform cutoff for each biomarker. A panel of IHC surrogates for each subtype of IBC is proposed. (Arch Pathol Lab Med. 2016; 140:806-814; doi: 10.5858/arpa.2015-0133-RA), Invasive breast cancers (IBCs) are heterogeneous, showing distinct molecular and pathologic features and biologic behavior. (1) Morphologically, there are 21 distinct subtypes of IBC as defined by the World Health [...]

Context.--Sarcomatoid urothelial carcinoma (UCa) is a rare but aggressive variant of bladder cancer that can show diagnostic challenges even using ancillary techniques. Objective.--To examine immunohistochemical markers in the context of sarcomatoid UCa, including those associated with epithelial-to-mesenchymal transition. Design.--Twenty-eight cases of sarcomatoid UCa were rereviewed. Clinical outcomes were obtained through database search. Immunohistochemistry for clinical and epithelial-to-mesenchymal transition markers was performed. Results.--All patients had biopsy-proven invasive UCa; 61% (17 of 28) had sarcomatoid UCa at initial diagnosis. A recognizable epithelial component(s) was present in 17 lesions. The sarcomatoid component accounted for 65% of the lesion (average), with heterologous elements present in 3 of 28 cases (11%). The morphologic spectrum of the sarcomatoid element included spindled not otherwise specified, myxoid, pseudoangiosarcomatous, and malignant fibrous histiocytoma-like undifferentiated features. The sarcomatoid component was immunoreactive for pancytokeratin (22 of 26; 85%), p63 (20 of 26; 77%), cytokeratin 903 (17 of 26; 65%), cytokeratin 7 (16 of 26; 62%), GATA3 (16 of 26; 62%), and cytokeratin 5/6 (16 of 26; 62%). STAT-6, CD31, CD34, and HMB45 were all nonreactive, whereas smooth muscle actin often showed at least focal immunoreactivity (22 of 26; 85%). Epithelial-to-mesenchymal transition markers were frequently expressed, including vimentin (26 of 26; 100%), FoxC2 (26 of 26; 100%), SNAIL (23 of 26; 88.5%), and ZEB1 (18 of 26; 69.2%). Follow-up was available for 24 patients (median, 7 months). Sixteen of 28 patients (57%) died of disease (overall mean survival, 9.1 months). The presence of myxoid or chordoid features was associated with reduced survival (P < .05). Conclusions.--Sarcomatoid UCa is an aggressive form of UCa that frequently expresses epithelial-to-mesenchymal transition markers, suggesting a possible mechanism associated with aggressive tumor behavior. (Arch Pathol Lab Med. 2016;140:543-551; doi: 10.5858/arpa.2015-0085-0A), Urothelial carcinoma (UCa) is the most common type of bladder cancer in the United States' accounting for greater than 90% of reported bladder cancer cases each year. (1) Numerous histologic [...]

Byline: F.L. Rice (1), K.M. Albers (2), B.M. Davis (3), I. Silos-Santiago (4), G.A. Wilkinson (5), A.M. LeMaster (2), P. Ernfors (6), R.J. Smeyne (7), H. Aldskogius (8), H.S. Phillips (9), M. Barbacid (4), T.M. DeChiara (10), G.D. Yancopoulos (10), C.E. Dunne (1), B.T. Fundin (6) Abstract: The impact of the nerve growth factor (NGF) family of neurotrophins and their receptors was examined on the cutaneous innervation in the mystacial pads of mice. Ten sets of unmyelinated and thinly myelinated sensory and autonomic innervation were evaluated that terminated in the epidermis, upper dermis, and upper part of the intervibrissal hair follicles. Mystacial pads were analyzed from newborn to 4-week-old mice that had homozygous functional deletions of the genes for NGF, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), neurotrophin-4 (NT-4), tyrosine kinase (trk) A, trkB, trkC, or p75. Mystacial pads were also analyzed in adult transgenic mice that had overproduction of NGF, BDNF, or NT-3 driven by a keratin promoter gene. The innervation was revealed by using immunofluorescence and immunocytochemistry with antibodies for protein gene product (PGP) 9.5, calcitonin gene-related product (CGRP), substance P (SP), galanin (GAL), neuropeptide Y (NPY), tyrosine hydroxylase (TH), and a neurofilament protein. The cumulative results indicated that NGF/trkA signaling plays a major role in the outgrowth and proliferation of sensory axons, whereas NT-3/trkA signaling plays a major role in the formation of sensory endings. TrkC is also essential for the development of three sets of trkA-dependent sensory innervation that coexpress CGRP, SP, and GAL. Another set of sensory innervation that only coexpressed CGRP and SP was solely dependent upon NGF and trkA. Surprisingly, most sets of trkA-dependent sensory innervation are suppressed by trkB perhaps interacting with p75. BDNF and NT-4 appear to mediate this suppressing effect in the upper dermis and NT-4 in the epidermis. In contrast to sensory innervation, sympathetic innervation to the necks of intervibrissal hair follicles depends upon NGF/trkA signaling interacting with p75 for both the axon outgrowth and ending formation. Although NT-3/trkA signaling is essential for the full complement of sympathetic neurons, NT-3 is detrimental to the formation of sympathetic terminations to the necks of hair follicles. TrkB signaling mediated by BDNF but not NT-4 also suppresses these sympathetic terminations. One sparse set of innervation, perhaps parasympathetic, terminating at the necks of hair follicles is dependent solely upon NT-3 and trkC. Taken together, our results indicate that the innervation of the epidermis, upper dermis, and the upper portion of hair follicles is regulated by a competitive balance between promoting and suppressing effects of the various neurotrophins. Author Affiliation: (1) Department of Pharmacology and Neuroscience, Albany Medical College, Albany, New York 12208 (2) Department of Pathology and Laboratory Medicine (3) Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky 40536 (4) Department of Molecular Biology, Bristol-Myers Squibb, Princeton, New Jersey 08543 (5) Department of Physiology and the Howard Hughes Medical Institute, University of California, San Francisco, California 94143 (6) Laboratory of Molecular Neurobiology, Karolinska Institute, Stockholm, Sweden S-171 77 (7) Saint Jude Children's Research Hospital, Memphis, Tennessee 38105 (8) Department of Anatomy, Uppsala University, Uppsala, Sweden S-751 23 (9) Department of Cell Genetics, Endocrine Research, and Neuroscience, Genentech, Inc., San Francisco, California 94080 (10) Regeneron Pharmaceuticals, Inc., Tarrytown, New York 10591 Article History: Received 22 January 1998; Accepted 26 January 1998

An analysis of keratin 18 null mice is reported. K18 is expressed in embryonic and simple adult epithelia, and K18 null mice are viable, fertile and have a normal lifespan. Hepatocytes in young K18 null mice were devoid of keratin filaments, although old K18 null mice developed a liver pathology with abnormal hepatocytes, which stained positively for ubiquitin and Mm120-1, identified as Mallory bodies.

Analysis of the biochemical features of the links between keratin intermediate filaments and desmosomal proteins which evolve into cadherin-mediated cytoskeletal complexes shows that the binding between the amino terminal 'head' of type II epidermal keratins and carboxy terminal 'tail' of desmoplankin is direct with a 18-amino acid residue stretch in K5 mediating the binding. The direct binding is not detectable with type I or epithelial type II keratins. The conservation of the 18-amino acid chain helps understand the role of a point mutation in the binding site.

Immunofluorescence microscopy and radiolabeling of the series of keratin polypeptide 18 (K18) mutations in the phosphorylation sites of human K18 reveal that ser-52 is the major phosphorylation site of human K18. Phosphorylation in the ser-52 site with protein kinase C, S6 kinase and CAM kinase contributes the in vivo filament rearrangement. K18 ser-52 mutant expression in the mammalian cells reveal low level phosphorylation.

An analysis of the Ras signal transduction route establishes keratin 18 (K18) as a direct target of this route. K18 transcription activation results from the action of activated Ha-Ras and activated Src, Lck or Raf. An enhancer component with Ets and AP-1 transcription factor binding regions mediates this activation. K18 and K8 are usually expressed in simple epithelial tissues and continuously expressed in various carcinomas.

The influence of epidermal growth factor receptor (EGFR) on keratin gene transcription has been investigated by transfecting DNAs with keratin promoters connected to a reporter gene into primary cultures of human epidermal keratinocytes with or without EGF, or by transforming growth factor alpha (TGF alpha). EGF particulary induces K6 and K16, markers of stimulated keratinocytes, through nuclear proteins that bind to EGF-responsive factors in the promoters of these keratin genes.

In addition to protecting epithelial cells from mechanical stress, keratins regulate cytoarchitecture, cell growth, proliferation, apoptosis, and organelle transport. In this issue, Vijayaraj et al. (2009. J. Cell Biol. doi:10.1083/ jcb.200906094) expand our understanding of how keratin proteins participate in the regulation of protein synthesis through their analysis of mice lacking the entire type II keratin gene cluster. doi 10.1083/jcb.200909134