Use of in situ detection of histone mRNA in the assessment of epidermal proliferation: comparison with the Ki67 antigen and BrdU incorporation

Identification of Significant Pathways Induced by PAX5 Haploinsufficiency Based on Protein-Protein Interaction Networks and Cluster Analysis in Raji Cell Line

PAX5 encodes a transcription factor essential for B-cell differentiation, and PAX5 haploinsufficiency is involved in tumorigenesis. There were few studies on how PAX5 haploinsufficiency regulated genes expression to promote tumorigenesis. In this study, we constructed the cell model of PAX5 haploinsufficiency using gene editing technology in Raji cells, detected differentially expressed genes in PAX5 haploinsufficiency Raji cells, and used protein-protein interaction networks and cluster analysis to comprehensively investigate the cellular pathways involved in PAX5 haploinsufficiency. The clusters of gene transcription, inflammatory and immune response, and cancer pathways were identified as three important pathways associated with PAX5 haploinsufficiency in Raji cells. These changes hinted that the mechanism of PAX5 haploinsufficiency promoting tumorigenesis may be related to genomic instability, immune tolerance, and tumor pathways.

Combinations of gene ontology and pathway characterize and predict prognosis genes for recurrence of gastric cancer after surgery

Gastric cancer (GC) is the second leading cause of death from cancer globally. The most common cause of GC is the infection of Helicobacter pylori, but ∼11% of cases are caused by genetic factors. However, recurrences occur in approximately one-third of stage II GC patients, even if they are treated with adjuvant chemotherapy or chemoradiotherapy. This is potentially due to expression variation of genes; some candidate prognostic genes were identified in patients with high-risk recurrences. The objective of this study was to develop an effective computational method for meaningfully interpreting these GC-related genes and accurately predicting novel prognostic genes for high-risk recurrence patients. We employed properties of genes (gene ontology [GO] and KEGG pathway information) as features to characterize GC-related genes. We obtained an optimal set of features for interpreting these genes. By applying the minimum redundancy maximum relevance algorithm, we predicted the GC-related genes. With the same approach, we further predicted the genes for the prognostic of high-risk recurrence. We obtained 1104 GO terms and KEGG pathways and 530 GO terms and KEGG pathways, respectively, that characterized GC-related genes and recurrence-related genes well. Finally, three novel prognostic genes were predicted to help supplement genetic markers of high-risk GC patients for recurrence after surgery. An in-depth text mining indicated that the results are quite consistent with previous knowledge. Survival analysis of patients confirmed the novel prognostic genes as markers. By analyzing the related genes, we developed a systematic method to interpret the possible underlying mechanism of GC. The novel prognostic genes facilitate the understanding and therapy of GC recurrences after surgery.

Contrasting expression patterns of histone mRNA and microRNA 760 in patients with gastric cancer

PURPOSE

Recent studies revealed that both disseminated tumor cells and noncancerous cells contributed to cancer progression cooperatively in the bone marrow. Here, RNA-seq analysis of bone marrow from gastric cancer patients was performed to identify prognostic markers for gastric cancer.

EXPERIMENTAL DESIGN

Bone marrow samples from eight gastric cancer patients (stages I and IV: n = 4 each) were used for RNA-seq analysis. Results were validated through quantitative real-time PCR (qRT-PCR) analysis of HIST1H3D expression in 175 bone marrow, 92 peripheral blood, and 115 primary tumor samples from gastric cancer patients. miR-760 expression was assayed using qRT-PCR in 105 bone marrow and 96 primary tumor samples. Luciferase reporter assays were performed to confirm whether histone mRNAs were direct targets of miR-760. miR-760 expression was also evaluated in noncancerous cells from gastric cancer patients.

RESULTS

RNA-seq analysis of bone marrow samples from gastric cancer patients revealed higher expression of multiple histone mRNAs in stage IV patients. HIST1H3D expression in the bone marrow, peripheral blood, and primary tumor of stage IV patients was higher than that in stage I patients (P = 0.0284, 0.0243, and 0.0006, respectively). In contrast, miR-760 was downregulated in the bone marrow and primary tumor of stage IV patients compared with stage I patients (P = 0.0094 and 0.0018, respectively). Histone mRNA and miR-760 interacted directly. Furthermore, miR-760 was downregulated in noncancerous mucosa in stage IV gastric cancer patients.

CONCLUSION

Histone mRNA was upregulated, whereas miR-760 was downregulated in the bone marrow and primary tumor of advanced gastric cancer patients, suggesting that the histone mRNA/miR-760 axis had a crucial role in the development of gastric cancer.

Specification and maintenance of oligodendrocyte precursor cells from neural progenitor cells: involvement of microRNA-7a

A gain-of-function study showed that miR-7a promoted the generation of oligodendrocytes (OL) and retained the cells in their precursor stage. Inhibiting miR-7a reduced oligodendrogenesis but expanded neuronal population. miR-7a might exert these effects by repressing the expression of proneural genes and regulators for OL differentiation.

The generation of myelinating cells from multipotential neural stem cells in the CNS requires the initiation of specific gene expression programs in oligodendrocytes (OLs). We reasoned that microRNAs (miRNAs) could play an important role in this process by regulating genes crucial for OL development. Here we identified miR-7a as one of the highly enriched miRNAs in oligodendrocyte precursor cells (OPCs), overexpression of which in either neural progenitor cells (NPCs) or embryonic mouse cortex promoted the generation of OL lineage cells. Blocking the function of miR-7a in differentiating NPCs led to a reduction in OL number and an expansion of neuronal populations simultaneously. We also found that overexpression of this miRNA in purified OPC cultures promoted cell proliferation and inhibited further maturation. In addition, miR-7a might exert the effects just mentioned partially by directly repressing proneuronal differentiation factors including Pax6 and NeuroD4, or proOL genes involved in oligodendrocyte maturation. These results suggest that miRNA pathway is essential in determining cell fate commitment for OLs and thus providing a new strategy for modulating this process in OL loss diseases.

Epidermal cell proliferation in the equine hoof wall

REASONS FOR PERFORMING STUDY

Current theories explaining how the hoof wall 'grows' and moves past the stationary distal phalanx are speculative and based on incomplete evidence. Movement in the lamellar region could occur by cell proliferation or an enzyme-based remodelling process. Since laminitis pathogenesis appears to involve increased transcription and activation of enzymes normally involved in tissue remodelling, it is important to know precisely which process dominates the lamellar region of the hoof..

OBJECTIVES

To investigate epidermal cell proliferation in the equine hoof wall and calculate a proliferative index (PI) for the coronet, lamellae and toe.

METHODS

An analogue of thymidine, 5-bromo-2'-deoxyuridine (BRdU), was infused i.v. into 5 ponies. After tissue harvesting, BRdU (and therefore basal cell proliferation) was detected immunohistochemically using mouse anti-BRdU. PIs were calculated for the coronet and 10 levels of the dorsal hoof wall lamellae.

RESULTS

The highest PIs (mean +/- s.e.) were in the coronet; 12.04% +/- 1.59 and proximal lamellae (7.13% +/- 1.92) and are therefore growth zones of the proximal hoof wall. PIs of more distal lamellae were 0.11% +/- 0.04 to 0.97% +/- 0.29; significantly lower (P = 0.05) than the lamellar growth zone.

CONCLUSIONS

A 20-fold PI decrease between proximal and more distal lamellae suggests that the majority of the normal lamellae are nonproliferative and their main function is to suspend the distal phalanx within the hoof capsule. Remodelling within the hoof wall epidermal lamellae, which must occur as the hoof wall moves past the stationary distal phalanx, is a process not requiring epidermal cell proliferation.

POTENTIAL RELEVANCE

A hoof lamellar epidermis that remodels using the same MMPs involved in laminitis pathogenesis implies that laminitis is a normal process out of control. Understanding MMP control and how the normal lamellar epidermis achieves this will help in the development of better laminitis preventative and treatment strategies.

H3 and H3.3 histone mRNA amounts and ratio in oral squamous cell carcinoma and leukoplakia

Histone variants (e.g. H3) play an important role in chromatin structure and gene expression regulation of normal cells. Aims of this study were to: (1) estimate H3 and H3.3 histone mRNA expressions and their ratio in oral squamous cell carcinoma (OSCC) and oral leukoplakia (OL); (2) investigate whether H3 and H3.3 variants could play a role in the pathogenesis of OSCC and OL, also conditionally to HPV infection, age, gender, and main habits (tobacco smoking and alcohol drinking) in human beings studied. Twenty-three cases of OSCC and 20 cases of OL were examined in lesion site (LS) and juxtaposed clinically undamaged site (JUS) by RT-PCR for H3 and H3.3 histone mRNA; 13 healthy oral mucosa samples (HS) were investigated in a single site as controls. HPV DNA presence was investigated in the respective exfoliated oral mucosa cells by nested PCR (nPCR: MY09-MY11/GP5-GP6). The data showed that both H3 and H3.3 histone mRNA crude concentrations are higher in OSCC (LS = 2901 +/- 459 ng of H3; JUS = 2699 +/- 658 ng of H3; LS = 3190 +/- 411 ng of H3.3; JUS = 2596 +/- 755 ng of H3.3) than those in OL (LS = 2095 +/- 349 ng of H3; JUS = 2192 +/- 897 ng of H3; LS = 2076 +/- 911 ng of H3.3; JUS = 1880 +/- 654 ng of H3.3) and in HS (2579 +/- 959 ng of H3; 2300 +/- 758 ng of H3.3), although not reaching any statistical significance. Interestingly, ratio of H3/H3.3 mRNA amounts decrease both in OSCC (0.99) and OL (1.009) vs HS (1.121). No association was found for H3 and H3.3 histone mRNA expressions in OSCC and OL with respect to HPV infection and the social-demographical variables considered (P > 0.2). The overall higher expression of H3.3 in damaged tissues up to the ratio inversion in OSCC especially in HPV+ alcohol drinkers (60.0%) represents the most interesting finding, in consideration of the proven ability of alcohol to act as permeability enhancer of human oral mucosa, to alter the mucosal structure and by this dynamics could favour the penetration through the epithelial layers of HPV.

High-dose glucocorticoids inhibit proliferation of rat olfactory epithelium

Glucocorticoids (GCs) are commonly prescribed for treatment of olfactory dysfunction. However, the effects of GCs on olfactory epithelium are not well known. We investigated the effects of high-dose GCs on proliferating cells of olfactory epithelium. Five adult male rats (300 g) received a single daily subcutaneous dose of vehicle containing 0.3 mg dexamethasone (DEX) for 9 days (DEX+ group), and a control group received vehicle alone (DEX- group). We compared sections from the two groups for numbers of Ki67-positive cells. The mean number of Ki67-positive cells per 500 olfactory epithelial cells was 9.6 for the DEX+ group and 58 for the DEX- group (significant difference). We conclude that high-dose GC suppressed proliferation of olfactory epithelium. We suggest that high-dose GC suppresses cytokines and growth factors, resulting in secondary suppression of proliferating ability.

Proliferation markers, proliferating cell nuclear antigen, Ki67, 5-bromo-2'-deoxyuridine, and cyclin D1 in mouse olfactory epithelium

We immunohistochemically identified proliferating cells in the olfactory epithelium of mice, using an anti-proliferating cell nuclear antigen (PCNA) antibody, an anti-Ki67 antibody, an anti-5-bromo-2'-deoxyuridine (BrdU) antibody, and an anti-cyclin D antibody. Positive cells stained by the 4 antibodies were identified mainly in the basal layer. The mean numbers of positive cells stained by the 4 antibodies in 500 olfactory epithelium cells from each animal were as follows: PCNA-positive cells 42, Ki67-positive cells 23, BrdU-positive cells 13.7, and cyclin D1-positive cells 9.2. PCNA may be detected in both proliferating and resting cells. Ki67 is an intranuclear antigen expressed in proliferating, but not resting, cells. Anti-BrdU antibodies might stain proliferating cells only following the S-phase, but not the G1-phase. Cyclin D1 is a protein that works during the G1-phase of the cell cycle. When we stain proliferating cells using proliferating cell markers, it is important to consider the cell cycle phases during which each marker stains.

Ectopic expression of luteinizing hormone-releasing hormone and peripherin in the respiratory epithelium of mice lacking transcription factor AP-2alpha

The vertebrate transcription factor activator protein-2 (AP-2alpha) is involved in craniofacial morphogenesis. In the nasal placode AP-2alpha expression delineates presumptive respiratory epithelia from olfactory epithelia, with AP-2alpha expression restricted to the anterior region of the respiratory epithelium (absent from the olfactory epithelium) at later stages. To address the role AP-2alpha plays in differentiation of cell groups in the nasal placode, the spatiotemporal expression pattern of four markers normally associated with olfactory epithelial structures was analyzed in mice lacking AP-2alpha. These markers were the intermediate filament protein peripherin, the neuropeptide luteinizing hormone-releasing hormone (LHRH), the neural cell adhesion molecule (NCAM) and the olfactory transcription factor Olf-1. Development of cells expressing these markers was similar in both genotypes until embryonic day 12.5 (E12.5), indicating that the main olfactory epithelium and olfactory pit formation was normal. At E13.5 in mutant mice, ectopic LHRH neurons and peripherin axons were detected in respiratory epithelial areas, areas devoid of Olf-1 and NCAM staining. Over the next few days, an increase in total nasal LHRH neurons occurred. The increase in nasal LHRH neurons could be accounted for by LHRH neurons arising and migrating out of respiratory epithelial regions on peripherin-positive fibers. These results indicate that AP-2alpha is not essential for the separation of the olfactory and respiratory epithelium from the nasal placode and is consistent with AP-2alpha preventing recapitulation of developmental programs within the respiratory epithelium that lead to expression of LHRH and peripherin phenotypes.

The temporal and spatial distribution of p21WAF expression in skin appendages

p21WAF is a cyclin-dependent kinase inhibitor which is widely expressed in epidermal structures. Using a combination of double immunocytochemical staining and combined in situ hybridization, we show that there is a striking exclusivity between the expression of Ki67 and p21WAF in the hair matrix. Some cells that are Ki67-positive also express p53, but as they exit the cell cycle they assume p21WAF-positive/p53-negative status. By contrast, cells in the interfollicular epidermis of psoriatic lesions, in the sebaceous gland, and in the outer root sheath are p21WAF-positive/p53-positive but Ki67-negative. These results suggest that in some anatomical parts of the epidermis, p21WAF expression can accompany p53 expression, whereas in other parts, the expression of these markers is reciprocal, suggesting that other pathways may be controlling p21WAF expression. In order to define, functionally, the presence of p53-independent p21WAF expression in skin, we examined lesions of Bowen's disease in which both alleles of p53 were inactivated. p21WAF expression was still observed, confirming a role for p53-independent expression of p21WAF in human skin in vivo.

In situ localization of S-phase-specific histone (H3) mRNA in Bowen's disease

PCNA and Ki-67 immunohistochemistry has been used to assess cell proliferation in place of tritiated thymidine or BrdU labeling of S-phase cells. Recently, it has been possible to reliably demonstrate histone H3 mRNA by in situ hybridization in formalin-fixed and paraffin-embedded tissue sections. We have compared this new proliferation marker with Ki-67 and PCNA with regard to distribution of positive cells and labeling indices (LI%) for 22 cases of Bowen's disease. In normal skin, Ki-67-IHC positive cells and histone mRNA positive cells were observed in the basal and suprabasal layers of the epidermis. In Bowen's disease, positive cells with each marker were more frequent in upper neoplastic epidermis than in suprabasal layers, and the average LI%s were markedly elevated with all markers, the scores decreasing in the following order: PCNA-IHC, Ki-67-IHC and H3mRNA-ISH. However, the results of double staining demonstrated that S-phase cells do not necessarily show exactly the same distributions as with PCNA and Ki-67-IHC labeling. H3mRNA-ISH showed three different degrees of reaction with significantly different LI%s, whereas PCNA and Ki-67 LI% did not vary essentially in the same areas. These results strongly suggest that Bowen's disease, which is well known as a low-grade neoplastic state with malignant potential, also demonstrates clear intratumoral heterogeneity of S-phase cells using the H3mRNA-ISH method.

Multiple roles for activated LEF/TCF transcription complexes during hair follicle development and differentiation

LEF/TCF DNA-binding proteins act in concert with activated beta -catenin, the product of Wnt signaling, to transactivate downstream target genes. To probe the role of activated LEF/TCF transcription factor complexes in hair follicle morphogenesis and differentiation, we engineered mice harboring TOPGAL, a beta -galactosidase gene under the control of a LEF/TCF and beta -catenin inducible promoter. In mice, TOPGAL expression was directly stimulated by a stabilized form of beta -catenin, but was also dependent upon LEF1/TCF3 in skin. During embryogenesis, TOPGAL activation occurred transiently in a subset of LEF1-positive cells of pluripotent ectoderm and underlying mesenchyme. Downgrowth of initiated follicles proceeded in the absence of detectable TOPGAL expression, even though LEF1 was still expressed. While proliferative matrix cells expressed the highest levels of Lef1 mRNAs, LEF1 concentrated in the precursor cells to the hair shaft, where TOPGAL expression was co-induced with hair-specific keratin genes containing LEF/TCF-binding motifs. LEF1 and TOPGAL expression ceased during catagen and telogen, but reappeared at the start of the postnatal hair cycle, concomitant with precortex formation. In contrast to hair shaft precursor cells, postnatal outer root sheath expressed TCF3, but not TOPGAL. TCF3 was also expressed in the putative follicle stem cells, and while TOPGAL was generally silent in this compartment, it was stimulated at the start of the hair cycle in a fashion that appeared to be dependent upon stabilization of beta -catenin. Taken together, our findings demonstrate that LEF1/TCF3 is necessary but not sufficient for TOPGAL activation, revealing the existence of positive and negative regulators of these factors in the skin. Furthermore, our findings unveil the importance of activated LEF/TCF complexes at distinct times in hair development and cycling when changes in cell fate and differentiation commitments take place.

Keratinocyte apoptosis and p53 expression in cutaneous lupus and dermatomyositis

Keratinocyte apoptosis may be induced by ultraviolet-B radiation and represents a potential source of fragmented autoantigens in autoimmune diseases. This study investigates whether excessive keratinocyte apoptosis occurs in the skin lesions of cutaneous lupus (CLE) and dermatomyositis (DM) and the potential mechanisms responsible for this phenomenon. Skin biopsies have been studied from 19 patients with CLE and DM, eight with scleroderma, and five healthy controls. Apoptosis was detected by in situ end-labelling of fragmented DNA. The expression of Bcl-2, PCNA, p53, and Ki-67 proteins was studied by immunohistochemistry. In DM and CLE skin, the number of apoptotic keratinocytes was significantly increased (p=0.008) compared with normal skin. In both diseases, a large accumulation of apoptotic keratinocytes and apoptotic bodies was present in the disrupted basal zone. Unlike normal skin, a large number of keratinocytes, particularly those morphologically apoptotic, expressed p53 protein. A significant increase in the number of proliferating Ki-67 positive (p=0.0007) and PCNA-positive (p=0.0008) nuclei was also observed. In both CLE and DM, exaggerated and inappropriate keratinocyte apoptosis occurs. It is associated with increased expression of p53 and PCNA. This suggests that normal solar radiation alone or in combination with additional local factors induces DNA damage and excessive keratinocyte apoptosis in these autoimmune diseases of the skin. Apoptosis can mediate the severe epidermal lesions observed in both diseases and the release of fragmented autoantigens into the dermis.

Epidermal cell kinetics by combining in situ hybridization and immunohistochemistry

Double labelling can serve as a useful tool for providing information about cell kinetics in normal and hyperproliferative tissues in general, and skin in particular. We have developed a double-labelling method that combines immunohistochemistry using the monoclonal antibody MIB1 and non-isotopic in situ hybridization using either a digoxigenin-labelled RNA probe specific for histone 3 mRNA sequences or a Fluorescein-labelled oligonucleotide probe specific for histone 2b, 3, 4 mRNA sequences. Double labelling was performed on normal, tape-stripped normal skin and psoriatic skin. The three proliferation markers were also examined by single labelling. The ratio of cells in the S-phase (Ns) and the growth fraction (Ncy) was determined. In normal skin, psoriatic skin and tape-stripped normal skin after 24 h and after 48 h, we calculated that 15%, 16%, 3% and 12% of growth fraction consisted of cells in the S-phase respectively. The S-phase lasts approximately 10 h, so the cell cycle time in normal and psoriatic skin is approximately 62.5 h. At present, the MIB1/H3 digoxigenin or MIB1/H2b-H3-H4 Fluorescein double-labelling technique cannot be used routinely. Therefore, in order to understand the cell kinetic processes better, experiments are recommended to optimize these methods. From a practical point of view and for reasons of specificity and sensitivity, we prefer the Fluorescein-labelled oligonucleotide probe method.

Prediction of human oral cancer radiation responsiveness by histone (H3) mRNA in situ hybridization: a preliminary report

PURPOSE

Cell cycle kinetics are believed to be a key determinant in radiation responsiveness. However, histomorphologic analysis remains an unreliable method of identifying proliferating cells. In this study, the fraction of cells undergoing division within oral cancer biopsy samples was used to predict the responsiveness of the tumor to radiation therapy.

PATIENTS AND METHODS

Eighteen cases of T1 or T2 squamous cell carcinoma of the floor of the mouth with known clinical outcomes were identified. All were treated at the Massachusetts General Hospital with external beam radiation therapy alone. The fraction of proliferating cells was determined using in situ hybridization of histone (H3) mRNA expression. Tissue viability and mRNA status was verified using in situ hybridization for beta-actin mRNA expression.

RESULTS

Matching the fraction of oral tumor cells positively labeled for histone (H3) mRNA (histone labeling index or HLI) with the actual clinical outcome showed that the HLI of radioresponsive oral tumors (12 cases) was 0.336+/-0.185 (approximately 34%+/-19%), whereas that for radioresistant oral tumors (six cases) was 0.088+/-0.078 (approximately 9%+/-7.8%). Using t-test statistical analysis for unpaired samples showed that the difference in HLI between the two groups was significantly different (P=.0068).

CONCLUSIONS

It is concluded that the use of in situ detection of histone (H3) mRNA may be a useful adjunctive criterion in the choice of treatment for human oral cancer.

Telomerase is not an epidermal stem cell marker and is downregulated by calcium

The ribonucleoprotein complex telomerase, which was found to be active in germ line, immortal, and tumor cells, and in cells from continuously renewing normal tissues such as epidermis or bone marrow, is thought to be correlated with an indefinite life span. Therefore, it has been postulated that in the normal tissues, telomerase activity may be restricted to stem cells, the possible precursors of tumor cells. Here, we demonstrate that a 56% enriched population of epidermal stem cells exhibited less telomerase activity than the more actively proliferating transit amplifying cells, which are destined to differentiate after a finite number of cell divisions. Thus telomerase is not a stem cell marker. In human epidermis we found a heterogeneous expression of the telomerase RNA component (hTR) within the basal layer, with clusters of hTR-positive cells showing variable activities. Histone-3 expressing S-phase basal cells were distributed evenly, illustrating that hTR upregulation may not strictly be correlated with proliferation. We further show for human epidermal cells that differentiation-dependent downregulation of telomerase correlates with Ca++-induced cell differentiation and that increasing the amount of Ca++ but not Mg++ or Zn++ reduced telomerase activity in a dose-dependent manner in a cell-free system (differentiation-independent). Furthermore, addition of ethyleneglycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid completely reversed this Ca++-induced inhibition. These data indicate that Ca++ is not only an important regulator of epidermal differentiation but also a key regulator of telomerase.

Detection of the Ki-67 proliferation associated nuclear epitope in normal canine tissues using the monoclonal antibody MIB-1

This report describes the immunohistochemical detection of the Ki-67 proliferation associated nuclear epitope by means of the MIB-1 monoclonal antibody (mAb) in paraffin tissue sections from nine samples of 16 tissues obtained from nine dogs. Three parameters were considered: the localization of the cells expressing the Ki-67 epitope, the cytological characteristics of the Ki-67 expression, and the proliferative activity of some of the tissues measured by means of the proliferative index (percentage of Ki-67 positive cells measured on 500 and 1000 cells). The MIB-1 mAb reacts with the nuclei of proliferating cells, as in humans. The proliferative index was far from representative, but we were able to give a range of values concerning the proliferative activity of normal tissues. This study serves as a basis for the expression of the Ki-67 antigen by normal canine tissues in order to visualize the proliferative compartments and, thus, allows its application as a proliferative marker in routine veterinarian histopathology.

The relationship between hyperproliferation and epidermal thickening in a mouse model for BCIE

Epidermal thickening is a phenomenon common to many genodermatoses but little is known about the underlying causes. We have recently created a mouse model for the human skin disease bullous congenital ichthyosiform erythroderma by gene targeting. Mice heterozygous for a truncated keratin 10 gene exhibit acanthosis and hyperkeratosis as seen in the human disease. The degree of epidermal thickening is highly variable, offering a novel opportunity to investigate how epidermal homeostasis is modulated in keratin disorders by comparing epidermis from different body regions. We have performed bromodeoxyuridine labeling experiments and detected proliferation antigens by immunohistochemical means to compare proliferation in the epidermis of wild-type and heterozygous mice. These results have been compared with the expression of epidermal differentiation markers and of the "hyperproliferation associated" keratins K6 and K16. These experiments indicated that hyperproliferation is only partly responsible for the morphologic changes and that other mechanisms such as decreased desquamation are likely to be involved.

In situ hybridization analysis of the expression of human telomerase RNA in normal and pathologic conditions of the skin

Human telomerase RNA (hTER) expression in skin was examined by in situ hybridization analysis. All newborn foreskins examined (n = 5) expressed hTER in epidermal basal cells at moderate levels. Telomerase RNA was not detectable in most adult specimens from sun protected areas (six of seven), whereas all samples obtained from sun exposed areas (n = 8) showed moderate hTER signals in epidermal basal cells. Telomerase RNA was also detected at moderate to strong levels in basal cells of psoriasis, contact dermatitis, and the proliferative cells of the anagen hair bulb. Basal cell carcinoma samples (14 of 15) had moderate to high hTER expression throughout the entire tumor, whereas squamous cell carcinomas (seven of eight) showed variable intensities of hTER expression but only in the cells at the periphery of tumor nests. All melanomas examined (n = 5) had moderate hTER expression in all tumor cells. The hTER signal intensities in skin tumors did not correlate with the age or sex of the donors, the clinical history of the lesions, or the histologic subtypes. To address whether hTER expression correlated with the proliferative state, sequential sections were stained with anti-Ki-67 antibody, a proliferation marker. In newborn foreskins, squamous cell carcinomas, and basal cell carcinomas, the distributions of hTER and Ki-67 were similar but not always identical. Telomerase RNA was more abundant than Ki-67 in the basal and suprabasal layer of newborn foreskins, suggesting that hTER expression is present both in actively cycling and in resting cells.

Proliferation and phenotype regulation in the subventricular zone during experimental allergic encephalomyelitis: in vivo evidence of a role for nerve growth factor

Proliferating cells in the subventricular zone (SVZ) of adult rat brain could provide a source of cells for repair attempts during degenerative diseases. However, very few reports dealt with the spontaneous regulation of this cell population during experimental conditions. In this paper, we describe an increase in the proliferation activity in the SVZ during experimental allergic encephalomyelitis, a demyelinating disease widely used as an experimental model for human multiple sclerosis. Moreover, p75(LNGFR)-immunoreactive elements in the SVZ were larger in experimental allergic encephalomyelitis compared with control groups, and they also showed multiple and branched elongations. Finally, a selective uptake of 125I-nerve growth factor was observed in the SVZ in neonatal rats, and positive elements migrated in the corpus callosum within a few days. These data indicate that cell populations in the SVZ are regulated during inflammatory conditions and degenerative diseases involving oligodendrocytes and neurotrophins, including nerve growth factor, could participate in these phenomena.

A comparative study of digoxigenin, 2,4-dinitrophenyl, and alkaline phosphatase as deoxyoligonucleotide labels in non-radioisotopic in situ hybridisation

AIM

To determine the optimum form of labelling and the most efficient reporter molecule for non-radioisotopic in situ hybridisation (ISH).

METHODS

Nine deoxyoligonucleotides complementary to histone mRNA were synthesised and labelled either enzymatically or during solid-phase synthesis with the reporter molecules digoxigenin, 2,4-dinitrophenyl (DNP), or alkaline phosphatase. Pooled deoxyoligonucleotide cocktails were then used in non-radioisotopic ISH detection of histone mRNA in human tonsil. Hybrid detection was by nitroblue tetrazoleum/5-bromo-4-chloro-3-indolyl phosphate colorimetric development.

RESULTS

The use of a spacer in 3' enzymatic labelling and when labelling with alkaline phosphatase significantly increased ISH signal. The 3' and 5' labelling of oligonucleotides with triple DNP groups during solid-phase synthesis produced the strongest signal as determined by the highest cell signal intensity and shortest development time.

CONCLUSIONS

3' and 5' solid-phase labelling with triple DNP groups produced the best labelling for non-isotopic ISH using deoxyoligonucleotide cocktails.

Bcl-2 overexpression in basaloid proliferations overlying dermatofibromas and basal cell carcinomas

Basaloid proliferations overlying dermatofibromas resembling superficial basal cell carcinomas have been interpreted both as reactive/regressive and frankly malignant. Basal cell carcinoma is a slow-growing tumour, which so far has been regarded as an actively proliferating lesion with a high apoptotic activity. We examined immunohistochemically 6,dermatofibromas with overlying simple hyperplasia, 12 dermatofibromas with overlying basaloid proliferations, and 24 basal cell carcinomas for expression of Ki-67 protein, and bcl-2 protein. The Ki-67 labelling index represents an estimate of proliferative activity. Bcl-2 protein suppresses apoptosis. The Ki-67 labelling indexes of basaloid proliferations, basal cell carcinomas, and normal epidermis were similar (11-15%, p < 0.05, Mann-Whitney test). Bcl-2 protein was expressed in all cells of basaloid proliferations, similar to the expression pattern in basal cell carcinomas. We suggest that basaloid proliferations overlying dermatofibromas might have achieved a phenotype that equals an early stage of BCC carcinogenesis.

Regulation of keratinocyte proliferation and differentiation by all-trans-retinoic acid, 9-cis-retinoic acid and 1,25-dihydroxy vitamin D3

We studied the effect of all-trans retinoic acid (all-trans-RA), 9-cis-retinoic acid (9-cis-RA) and 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) on proliferation and differentiation of human keratinocytes cultured in a submerged culture system for up to 5 weeks and evaluated changes in cell morphology and in the expression of proliferation- and terminal differentiation-related genes on both the mRNA and the protein levels. Under control culture conditions, the expression of small proline-rich proteins (SPRR1 and SPRR2), involucrin, Ki67 and c-jun reached a maximum after 2 weeks in culture (1 week postconfluence) and then decreased as the tissue architecture of the cultures deteriorated. Upon simultaneous treatment with both retinoids and 1,25(OH)2D3 a culture was generated that remained stable for 4 weeks with at least eight living cell layers. Furthermore, this culture showed a pattern of SPRR2 and involucrin expression which closely resembled that of native epidermis, a maintained Ki67 expression and a strongly induced c-jun expression. Treatment with 1,25(OH)2D3 alone inhibited cell proliferation and stimulated cell differentiation resulting in acceleration of the differentiated phenotype and was accompanied by inhibition of c-jun and Ki67 expression and also, surprisingly by inhibition of SPRR1, SPRR2 and involucrin expression. In contrast, treatment with all-trans-RA and/or 9-cis-RA induced a more proliferative phenotype with a prolonged lifespan as compared to control cultures. SPRR1 was weakly repressed, SPRR2 was strongly repressed, a delayed induction of involucrin occurred, and c-jun and Ki67 expression were maintained. These results show that modulation of the composition of the medium by the addition of various vitamins results in changes in the balance between keratinocyte proliferation and differentiation which correspond to changes in the expression of proliferation and differentiation markers and prolongation of the culture lifespan.

Prognostic value of Ki67 antigen expression in basal cell carcinomas

Recurrence of basal cell carcinoma (BCC) following treatment is a common event and long-term follow-up of all patients presenting with a primary BCC has been recommended. Proliferation indices have been recognized as important prognostic factors in several tumour types in a variety of cancer systems, being significantly elevated in more aggressive lesions. We have examined 51 BCCs (17 non-recurrent tumours [group 1], 17 original tumours which later recurred [group 2-O], and the corresponding 17 recurrent specimens [group 2-R]) for Ki67 antigen expression, a proliferation-associated antigen using immunohistochemistry with the monoclonal antibody MIB1. There was a significant increase in the percentage positive for MIB1 in the Group 2-O as compared with the group 1 BCCs (P < 0.05). p53 protein expression, as assessed by immunohistochemistry with the monoclonal antibody DO7, was similar in each group. These results show that Ki67 antigen expression differs between BCCs which later recur and BCCs that do not recur.