Long-term exposure of immortalized keratinocytes to arsenic induces EMT, impairs differentiation in organotypic skin models and mimics aspects of human skin derangements

Arsenic is one of the most important human carcinogens and environmental pollutants. However, the evaluation of the underlying carcinogenic mechanisms is challenging due to the lack of suitable in vivo and in vitro models, as distinct interspecies differences in arsenic metabolism exist. Thus, it is of high interest to develop new experimental models of arsenic-induced skin tumorigenesis in humans. Consequently, aim of this study was to establish an advanced 3D model for the investigation of arsenic-induced skin derangements, namely skin equivalents, built from immortalized human keratinocytes (NHEK/SVTERT3-5). In contrast to spontaneously immortalized HACAT cells, NHEK/SVTERT3-5 cells more closely resembled the differentiation pattern of primary keratinocytes. With regard to arsenic, our results showed that while our new cell model was widely unaffected by short-time treatment (72 h) with low, non-toxic doses of ATO (0.05-0.25 µM), chronic exposure (6 months) resulted in distinct changes of several cell characteristics. Thus, we observed an increase in the G2 fraction of the cell cycle accompanied by increased nucleus size and uneven tubulin distribution. Moreover, cells showed strong signs of de-differentiation and upregulation of several epithelial-to-mesenchymal transition markers. In line with these effects, chronic contact to arsenic resulted in impaired skin-forming capacities as well as localization of ki67-positive (proliferating) cells at the upper layers of the epidermis; a condition termed Bowen's disease. Finally, chronically arsenic-exposed cells were characterized by an increased tumorigenicity in SCID mice. Taken together, our study presents a new model system for the investigation of mechanisms underlying the tumor-promoting effects of chronic arsenic exposure.

One-year persistence of individual gait patterns identified in a follow-up study - A call for individualised diagnose and therapy

Although a hunch about the individuality of human movements generally exists, differences in gait patterns between individuals are often neglected. To date, only a few studies distinguished individual gait patterns in terms of uniqueness and emphasised the relevance of individualised diagnoses and therapy. However, small sample sizes have been a limitation on identifying subjects based on gait patterns, and little is known about the permanence of subject-specific characteristics over time. The purpose of this study was (1) to prove the uniqueness of individual gait patterns within a larger sample and (2) to prove the long-term permanence of individual gait patterns. A sample of 128 healthy participants each walked a distance of 10m barefoot 10 times. Two force plates recorded the ground reaction forces during a double step at a self-selected walking speed. A subsample of 46 participants repeated this procedure after a period of 7-16 months. The application of support vector machines resulted in classification rates of 99.8% (1278 out of 1280) and 99.4% (914 out of 920) for the initial subject-classification and the subsample follow-up-classification, respectively. The results showed that gait patterns based on time-continuous ground reaction forces were unique to an individual and could be differentiated from those of other individuals. Support vector machines classified gait patterns to the corresponding individual almost error-free. Hence, human gait is not only different between individuals but also exhibits unique individual characteristics that are persistent over years. Our findings provide evidence for the individual nature of human walking and emphasise the need to evaluate individualised clinical approaches for diagnoses and therapy.

ELMO3 predicts poor outcome in T1 laryngeal cancer

OBJECTIVES

Despite the excellent overall survival of 92%-97% in early glottic cancer, recurrence rates of 13%-20% have not improved in the last decades. The engulfment and cell motility protein 3 (ELMO3) have been described as prognostic marker in patients with lung cancer. The aim of this study was to investigate the expression of ELMO3 in early laryngeal cancer patients treated with TLM and to evaluate its prognostic significance on clinical outcome.

DESIGN, SETTING AND PARTICIPANT

Forty-eight patients with glottic carcinoma (T1N0M0) that underwent primary treatment with TLM between 1994 and 2012 were analysed. ELMO3 expression of the tumour was assessed using immunohistochemistry and correlated with clinical data.

MAIN OUTCOME MEASURE

Overall survival, disease-specific survival (DSS) and disease-free survival (DFS) rates RESULTS: Positive ELMO3 expression was found in 23% of the patients and was correlated with poor DSS and DFS (P<.05).

CONCLUSION

This is the first study to show a prognostic effect of positive ELMO3 expression in early glottic carcinoma patients.

Proteome analysis identifies L1CAM/CD171 and DPP4/CD26 as novel markers of human skin mast cells

BACKGROUND

The function of skin mast cells has been well documented in IgE-mediated allergic reactions, whereas other mast cell functions are poorly defined. This study aimed at identifying novel mast cell proteins by proteome analysis of primary human skin mast cells.

METHODS

The proteome of skin mast cells was compared to other cell types and analyzed using bioinformatics. The expression and function of two proteins hitherto not described in skin mast cells was investigated in isolated mast cells as well as in mast cells in situ.

RESULTS

Within the mast cell proteome, we identified 49 highly expressed proteins previously not described in mast cells; 21 of these proteins were found to be selectively expressed in mast cells. Two proteins, the neural cell adhesion molecule L1 and dipeptidyl peptidase 4, were further studied. L1 was found to be highly expressed in mast cells in normal, psoriasis, and mastocytosis skin. Dipeptidyl peptidase 4 was found to be expressed in mast cells in normal, psoriasis, and mastocytosis skin as well as in bone marrow mast cells in patients with systemic mastocytosis. In normal skin, mast cells were identified as a major source of dipeptidyl peptidase 4 and we also found that skin mast cells and fibroblasts secrete an active form of this enzyme.

CONCLUSIONS

In a systematic proteomics approach we identified two novel mast cell proteins potentially relevant to skin homeostasis: neural cell adhesion molecule L1 and dipeptidyl peptidase 4.

Histamine suppresses epidermal keratinocyte differentiation and impairs skin barrier function in a human skin model

Background

Defects in keratinocyte differentiation and skin barrier are important features of inflammatory skin diseases like atopic dermatitis. Mast cells and their main mediator histamine are abundant in inflamed skin and thus may contribute to disease pathogenesis.

Methods

Human primary keratinocytes were cultured under differentiation-promoting conditions in the presence and absence of histamine, histamine receptor agonists and antagonists. The expression of differentiation-associated genes and epidermal junction proteins was quantified by real-time PCR, Western blot, and immunofluorescence labeling. The barrier function of human skin models was tested by the application of biotin as tracer molecule.

Results

The addition of histamine to human keratinocyte cultures and organotypic skin models reduced the expression of the differentiation-associated proteins keratin 1/10, filaggrin, and loricrin by 80–95%. Moreover, the addition of histamine to skin models resulted in the loss of the granular layer and thinning of the epidermis and stratum corneum by 50%. The histamine receptor H1R agonist, 2-pyridylethylamine, suppressed keratinocyte differentiation to the same extent as did histamine. Correspondingly, cetirizine, an antagonist of H1R, virtually abrogated the effect of histamine. The expression of tight junction proteins zona occludens-1, occludin, claudin-1, and claudin-4, as well as that of desmosomal junction proteins corneodesmosin and desmoglein-1, was down-regulated by histamine. The tracer molecule biotin readily penetrated the tight junction barrier of skin cultures grown in the presence of histamine, while their diffusion was completely blocked in nontreated controls.

Conclusions

Our findings suggest a new mechanism by which mast cell activation and histamine release contribute to skin barrier defects in inflammatory skin diseases.

Psoriasin (S100A7) is a major Escherichia coli-cidal factor of the female genital tract

The female urogenital tract requires an efficient defense against bacteria, potentially derived from the adjacent intestinal tract. We have thus sought to identify the factors that protect against Escherichia coli (E. coli) in the female genital tract. Vaginal fluid from healthy human donors consistently killed E. coli in vitro and vaginal epithelium strongly expressed and secreted psoriasin. Psoriasin was constitutively produced in an organotypic vaginal epithelium model, and exposure of these cells to supernatants of E. coli cultures led to an enhanced psoriasin expression. Secreted psoriasin in vaginal fluids accounted for approximately 2.5-3% of total protein. Fractionation of vaginal fluids by high performance liquid chromatography (HPLC) showed that psoriasin co-eluted with a peak of E. coli killing activity. Our data show that normal vaginal fluid contains a powerful intrinsic antimicrobial defense against E. coli and that psoriasin contributes to the innate immune response of the female genital tract.

Irradiated cultured apoptotic peripheral blood mononuclear cells regenerate infarcted myocardium

BACKGROUND

Acute myocardial infarction (AMI) is followed by post AMI cardiac remodelling, often leading to congestive heart failure. Homing of c-kit+ endothelial progenitor cells (EPC) has been thought to be the optimal source for regenerating infarcted myocardium.

METHODS

Immune function of viable peripheral blood mononuclear cells (PBMC) was evaluated after co-culture with irradiated apoptotic PBMC (IA-PBMC) in vitro. Viable PBMC, IA-PBMC and culture supernatants (SN) thereof were obtained after 24 h. Reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay were utilized to quantify interleukin-8 (IL-8), vascular endothelial growth factor, matrix metalloproteinase-9 (MMP9) in PBMC, SN and SN exposed fibroblasts. Cell suspensions of viable- and IA-PBMC were infused in an experimental rat AMI model. Immunohistological analysis was performed to detect inflammatory and pro-angiogenic cells within 72 h post-infarction. Functional data and determination of infarction size were quantified by echocardiography and Elastica van Gieson staining.

RESULTS

The IA-PBMC attenuated immune reactivity and resulted in secretion of pro-angiogenic IL-8 and MMP9 in vitro. Fibroblasts exposed to viable and IA-PBMC derived SN caused RNA increment of IL-8 and MMP9. AMI rats that were infused with IA-PBMC cell suspension evidenced enhanced homing of endothelial progenitor cells within 72 h as compared to control (medium alone, viable-PBMC). Echocardiography showed a significant reduction in infarction size and improvement in post AMI remodelling as evidenced by an attenuated loss of ejection fraction.

CONCLUSION

These data indicate that infusion of IA-PBMC cell suspension in experimental AMI circumvented inflammation, caused preferential homing of regenerative EPC and replaced infarcted myocardium.

[The role of nitric oxide in reproduction]

Nitrix oxide (NO) is a highly reactive and short-lived radical (half-life time: 10-12 s), which is derived from L-arginine by the NO synthases (NOS) in several organ systems. The release of NO by endothelial cells leads to rapid relaxation of vascular smooth muscle cells, whereas release by several neuronal cells causes neurotransmission. When NOS is actively induced in immune cells or certain epithelia it causes cytotoxicity and/or apoptosis of these cells. In the reproductive organs NO is now considered to be an important trigger molecule for several physiological mechanisms. Follicular synthesized NO is involved in rupture of the follicle during ovulation. Moreover, NO participates in the acrosome reaction of spermatozoa during capacitation. Apoptosis and collagenolysis of the functional endometrium may be involved in endometrial shedding during menstruation. Since NO induces both apoptosis and collagenolysis, the newly discovered production of NO in late secretory endometrium could act as a key mechanism in the process of menstrual disintegration of the endometrium. Additionally, NO is necessary to support and maintain the decidualization process and plays a pivotal role in implantation.

Keratinocytes express the CD146 (Muc18/S-endo) antigen in tissue culture and during inflammatory skin diseases

The CD146 (or MUC18/MEL-CAM) antigen is a cell adhesion molecule of the immunoglobulin superfamily. Besides in melanoma, expression of CD146 antigen has been demonstrated in breast epithelia and hair follicles. We studied its expression by human keratinocytes in culture as well as in neoplastic and inflammatory skin diseases. Staining of primary cultured keratinocytes revealed expression of CD146 on the cell membrane, preferentially on cell-cell contact sites. Western blot analysis of keratinocytes detected a band of approximately 113 kDa, corresponding to the CD146 protein. In contrast to primary keratinocytes, neither CD146 protein nor mRNA expression was found in the keratinocyte-derived cell lines A431 and HaCaT. Treatment of keratinocytes with the proinflammatory cytokines interleukin-1 and interleukin-6, tumor necrosis factor-alpha, and interferon-gamma, resulted in no change of CD146 expression and incubation with phorbol 12-myristate 13-acetate led to a reduction of CD146 on keratinocytes. By contrast, when culturing keratinocytes in medium devoid of growth supplements, a distinct upregulation was observed as compared with culture in fully supplemented medium. In normal human epidermis expression of the CD146 antigen was not detectable. It was strongly upregulated, however, on suprabasal keratinocytes in psoriasis, in lichen planus, in the epidermis overlying skin neoplasms, and in viral warts. In squamous cell carcinomas and basal cell carcinomas only a minority of tumor cells expressed CD146. Our findings suggest that the CD146 antigen represents an activation marker of keratinocytes and may be involved in cutaneous inflammatory tissue reaction.

Characterization of a cDNA clone, encoding a 70 kDa heat shock protein from the dermatophyte pathogen Trichophyton rubrum

Trichophyton rubrum is an anthropophilic fungus causing up to 90% of chronic cases of dermatophytosis. To characterize T. rubrum proteins at the molecular level, we established a cDNA library of this pathogen. Here we describe a recombinant cDNA clone identical to eukaryotic 70kDa heat-shock proteins (HSPs). Western blot analysis using an anti HSP70 monoclonal antibody detected a recombinant fusion protein in Escherichia coli transformed with the expression vector containing the cloned cDNA insert. Southern blot analysis of T. rubrum genomic DNA detected no other members of the HSP70 gene family. Further analysis revealed the presence of two introns within the ORF of the HSP70 gene. In Northern blot analysis, the cDNA clone was hybridized to a RNA species of about 3.5kb which was constitutively expressed by cells cultured at 27 degrees C and was strongly up-regulated after culture at 37 degrees C. In summary, we have cloned the first member of the HSP family of dermatophytes and characterized it as a member of the Dnak subfamily of 70kDa HSPs.

001: hepatocyte growth factor/scatter factor inhibits UVB induced apoptosis of human keratinocytes via the PI-3-kinase pathway

UVB-irradiation induces apoptosis in primary keratinocytes (KC) and KC-derived cell-lines A431 and HaCaT. Here we report on the inhibition of UV induced KC-apoptosis by hepatocyte growth factor/scatter factor (HGF/SF). The protective effect of HGF/SF for UVB-irradiated primary KC was observed at concentrations as low as 1 ng/ml HGF and was confirmed by demonstration of the inhibition of nucleosome-release and the activation of caspase-3. In contrast to the observation with primary KC HGF/SF had no effect on the survival of A431 and HaCaT cells after UVB-irradiation, despite the fact that we could demonstrate that these cells functionally express the HGF/SF receptor c-met. When blocking signalling pathways initiated by c-met, we found that the inhibition of the phosphatidylinositol-3-OH (PI-3) kinase by wortmannin or LY294002 led to a total inhibition of the anti-apoptotic effect of HGF/SF, whereas the blockade of the MAP-kinase pathway by PD90859 had no effect. This represents the first demonstration of an involvement of the PI-3 kinase pathway in the anti-apoptotic effect of HGF/SF. In conclusion, our data demonstrate that HGF/SF is able to rescue KC but not autonomously growing KC cell lines from apoptosis induced by UVB. Since in vivo HGF/SF is produced by mesenchymal cells, this mechanism may represent an important paracrine loop in the skin supporting the survival of KC after UV-injury.

UVA and UVB radiation differentially regulate vascular endothelial growth factor expression in keratinocyte-derived cell lines and in human keratinocytes

Vascular endothelial growth factor (VEGF) is a central regulator of neoangiogenesis in inflammatory and neoplastic conditions. Ultraviolet irradiation is one of the mainstays of dermatological therapy for various inflammatory skin diseases. In the present study we have compared the effects of UV irradiation on the production of VEGF by keratinocytes (KC) and by the KC-derived cell lines A431 and HaCaT. Irradiation of A431 and HaCaT cells with both UVA (10 J/cm2 and 20 J/cm2) and UVB (8 mJ/cm2 and 16 mJ/cm2) led to strong upregulation of VEGF mRNA and protein. Induction of VEGF by UVA and UVB in these cells was mediated by different pathways, i.e. the generation of free radicals and the secretion of (a) soluble factor(s), respectively. Unlike KC-derived cell lines, no increase in VEGF production was observed in KC in primary culture after irradiation with the same UV doses. Increasing the irradiation dose in these cells of UVA to 40 J/cm2 led to a marked decrease in soluble VEGF, whereas doses as high as 32 mJ/cm2 UVB only minimally affected VEGF levels. Reduction of VEGF production by KC might contribute to the effect of UVA irradiation in inflammatory skin diseases. The differential response of primary KC and autonomously growing KC-derived cell lines to the induction of VEGF by UV light could favor neoangiogenesis in the vicinity of epidermal tumor cells in vivo, thereby endowing them with a growth advantage over normal cells.

Expression of inducible nitric oxide synthase in human breast cancer depends on tumor grade

Expression of inducible nitric oxide synthase (iNOS) by tumor cells has been suggested to abrogate metastasis in several tumor models, whereas constitutive NOS expression correlated positively with tumor grade in human breast carcinoma. Whether or not expression of one of the various NOS isoforms could predict the prognosis of breast cancer, however, has not been established. In the present report we investigated the cellular distribution of NOS isoforms in a series of benign and malignant breast tumors and in normal breast tissue. Immunohistochemistry revealed that in samples of benign disease the number of iNOS+ epithelial cells or total epithelial cells was 69+/-16% (n = 50). In samples of grade II invasive ductal breast carcinomas the number of iNOS+ tumor cells or total tumor cells was 62+/-20% (n = 40), compared to 12+/-9% (n = 40) in samples of grade III carcinomas (P<0.0001). iNOS protein was also identifiable in most of the epithelial cells of normal breast tissue (n = 4). In contrast, eNOS protein was restricted to vascular endothelial cells in all of the specimens studied. Since the presence of tumor cell iNOS protein is inversely related to the tumor's metastatic potential, we conclude that endogenous tumor cell mediated iNOS expression might have an inhibitory effect on the metastatic process in breast cancer.

Hepatocyte growth factor increases expression of vascular endothelial growth factor and plasminogen activator inhibitor-1 in human keratinocytes and the vascular endothelial growth factor receptor flk-1 in human endothelial cells

The pleiotropic growth factor hepatocyte growth factor/scatter factor (HGF/SF) has been implicated by clinical and experimental studies in repair mechanisms in different organs and tissues. However, no data on the impact of HGF/SF in wound healing in the skin are yet available. Proliferating and migrating keratinocytes play a major role in repair processes in the skin by closing the wound. Recent evidence gathered from studies that used gene-deficient mice has implicated the plasminogen activator (PA)/plasmin system in wound healing, which depends on controlled matrix degradation and deposition during cell migration and proliferation. Furthermore, keratinocytes are an important source of vascular endothelial growth factor (VEGF), which is a potent inducer of angiogenesis. In this study, we show that in human keratinocytes HGF/SF but not the related cytokine macrophage stimulating protein (MSP) significantly increases expression of VEGF and plasminogen activator inhibitor-1 (PAI-1) on the level of protein and mRNA. Furthermore, we demonstrate that HGF/SF increases the expression of the VEGF receptor flk-1 in human endothelial cells and that, in an angiogenesis co-culture assay of endothelial cells and keratinocytes, HGF/SF increases endothelial cell tube formation significantly. Therefore, we propose a role for HGF/SF in wound repair in the skin: HGF/SF--produced by activated fibroblasts--increases in keratinocytes the expression of PAI-1, which leads to increased matrix stability during the repair process and which could also limit activation of HGF/SF by proteases such as urokinase-type PA (u-PA) or tissue-type PA (t-PA). Furthermore HGF/SF also increases the expression of VEGF in these cells, thereby initiating angiogenesis in a paracrine manner. This effect would be enhanced by an increased responsiveness of endothelial cells toward VEGF, resulting from the HGF/SF-induced up-regulation of flk-1 on these cells.

Inducible nitric oxide synthase (iNOS) expression may predict distant metastasis in human melanoma

Expression of inducible nitric oxide synthase (iNOS) and its cellular localization was investigated in subcutaneous or lymph node metastases of human melanoma. Immunohistochemistry revealed that iNOS expression was limited to melanoma cells. In samples of patients without distant metastases, the number of iNOS+ tumour cells/total tumour cells was 55% +/- 17% (n = 12) compared with 9% +/- 8% when distant metastases of lung, liver or brain occurred within an observation period of 3 years (n = 10) (P < 0.001). Western blotting confirmed the expression of iNOS protein in select cases. Notably, iNOS is expressed in regional melanoma metastases and its expression is inversely related to the tumour's metastatic potential. Thus, iNOS expression may have predictive value for the development of distant metastases of human melanoma.

Expression of vascular endothelial growth factor receptor-3 and podoplanin suggests a lymphatic endothelial cell origin of Kaposi's sarcoma tumor cells

Despite intensive research over the past decade, the exact lineage relationship of Kaposi's sarcoma (KS) tumor cells has not yet been settled. In the present study, we investigated the expression of two markers for lymphatic endothelial cells (EC), ie, vascular endothelial growth factor receptor-3 (VEGFR-3) and podoplanin, in AIDS and classic KS. Both markers were strongly expressed by cells lining irregular vascular spaces in early KS lesions and by tumor cells in advanced KS. Double-staining experiments by confocal laser microscopy established that VEGFR-3-positive and podoplanin-positive cell populations were identical and uniformly expressed CD31. By contrast, these cells were negative for CD45, CD68, and PAL-E, excluding their hemopoietic and blood vessel endothelial cell nature. Podoplanin expression in primary KS tumor lysates was confirmed by Western blot analysis. Both splice variants of VEGFR-3 were found in KS-tumor-derived RNA by RT-PCR. In contrast to KS tumor cells in situ, no expression of VEGFR-3 and podoplanin was detected in any of four KS-derived spindle cell cultures and in one KS-derived autonomously growing cell line (KS Y-1). Our findings that KS tumor cells express two lymphatic EC markers in situ strongly suggest that they are related to or even derived from the lymphatic EC lineage. Lack of these antigens on cultured cells derived from KS lesions indicates that they might not represent tumor cells that grow in tissue culture, but rather other cell types present in KS lesions.

Retinoids downregulate vascular endothelial growth factor/vascular permeability factor production by normal human keratinocytes

Normal human keratinocytes (KC) are a prominent source of vascular endothelial growth factor (VEGF)/vascular permeability factor (VPF), both in vivo and in tissue culture. In this report we have investigated the influence of retinoids, which are used to treat several skin diseases, on VEGF/VPF production by KC. All-trans retinoic acid (RA), 13-cis RA, and all-trans retinol reduced VEGF/VPF secretion by KC in primary cultures by a mean +/- SD of 58 +/- 25%, 46 +/- 21%, and 54 +/- 20%, respectively, compared with control values. Reductions were observed at concentrations as low as 10(-10)M for all-trans RA, a level that is easily reached in vivo during retinoid treatment. The reduction in VEGF/VPF protein by 10(-6)M all-trans RA was paralleled by a strong downregulation of VEGF/VPF mRNA levels. In contrast to normal KC, all-trans RA had no effect on the HaCaT keratinocyte cell line, and it stimulated VEGF/VPF release by the epidermoid carcinoma cell line A431 2-fold. Our data demonstrate that retinoids are potent inhibitors of VEGF/VPF production by normal human KC. Downregulation of VEGF/VPF production in these cells by retinoids may contribute to the therapeutic effects or retinoids in diseases that are accompanied by angioproliferation, such as psoriasis.

Vascular endothelial growth factor is constitutively expressed in normal human salivary glands and is secreted in the saliva of healthy individuals

The expression of vascular endothelial growth factor (VEGF), a specific mitogen for endothelial cells, was examined in salivary glands and in normal saliva. In normal salivary glands, VEGF mRNA and protein were strongly present in acinar cells, whereas little or no VEGF was found in ductal cells. In chronically inflamed glands, VEGF protein was in addition present in ductal elements and in infiltrating mononuclear cells. No difference of VEGF expression was observed between benign and malignant salivary gland tumours. By ELISA, whole saliva of 24 healthy individuals contained up to 2.5 ng/ml (mean 1.4 ng/ml; SD 0.77 ng/ml) of VEGF, confirming the constitutive secretion of this cytokine by human salivary glands. Western blot analysis of normal saliva under non-reducing conditions detected anti-VEGF reactive protein moieties of approximately 46 kD, corresponding to VEGF secreted by cells in tissue culture. Additional anti-VEGF reactive proteins of approximately 60 and 90 kD were detected in the saliva of some individuals. The presence of considerable quantities of VEGF in normal human saliva suggests an important role for this cytokine in the maintenance of the homeostasis of mucous membranes, with rapid induction of neoangiogenesis by salivary VEGF helping to accelerate wound healing within the oral cavity. Moreover, salivary VEGF may permeabilize intraglandular capillaries and thus participate in the regulation of saliva production itself.

Nitric oxide synthases in Kaposi's sarcoma are expressed predominantly by vessels and tissue macrophages

Kaposi's sarcoma (KS) is a tumor of presumed vascular origin frequently found in patients with AIDS. Recent data suggest that the development of KS is linked with the presence of a newly recognized herpesvirus, human herpesvirus type 8. Nitric oxide (NO), a messenger molecule with vasoactive, antitumor, and antimicrobial effects, is produced by three isoforms of nitric oxide synthases (NOS). In the present report, we investigated the expression of NOS isoforms in KS. By NADPH-diaphorase histochemistry, NOS activity was detectable in endothelia and CD45+ cells within KS lesions. Reactivity for endothelial NOS (eNOS) was found in blood vessel endothelia; however, eNOS reactivity was negative in KS spindle cells in 12 of 17 tumors, and moderately positive in the other 5 lesions. In contrast to KS, tumor cells in three hemangiomas and one angiosarcoma were strongly positive for eNOS. Inducible NOS (iNOS) was absent from KS tumor cells but was found regularly in CD45+, HLA-DR+ cells within the lesions. In five KS-derived spindle cell cultures, neither eNOS nor iNOS proteins were detectable. The sporadic expression of eNOS by KS spindle cells in vivo and the absence of eNOS protein from KS spindle cells in tissue cultures argue against the possibility that the cells are derived from blood vessel endothelia. The consistent expression of iNOS by CD45+, HLA-DR+ cells within KS lesions strongly suggests that leukocyte-derived NO participates in the pathology of this tumor.

Identification of a human cDNA encoding a novel Bcl-x isoform

Alternative splicing has been shown to generate two isoforms of the apoptosis regulator bcl-x, Bcl-xL and Bcl-xS, in humans. Here we describe the identification and characterization of a third splice variant of the human bcl-x gene. It differs from previously described bcl-x transcripts in two respects: (1) a novel facultative intron is spliced out at the 5' untranslated region and (2) the open reading frame arises from a continuous genomic sequence extending over the splice donor sites utilized by the bcl-xL and bcl-xS transcripts. Since the resulting molecule has an organisation homologous to mouse and rat Bcl-x beta we suggest calling this novel protein human Bcl-x beta. Northern blot analysis revealed that bcl-x beta mRNA is expressed in numerous cell lines. Like Bcl-xL, h-Bcl-x binds to the pro-apoptotic protein Bax, suggesting a functional activity in vivo.

Induction of inducible nitric oxide synthase expression in human secretory endometrium

The endometrial secretory phase is characterized by stromal oedema, a premenstrual increase in stromal macrophages and an increased cytokine production as menstruation approaches. Nitric oxide (NO) is a mediator of vasodilatation and cytotoxicity which is synthesized from L-arginine by NO synthases (NOS). These enzymes are either constitutively expressed or induced by lipopolysaccharides and/or cytokines. The presence and function of the inducible isoform of NOS (iNOS) in normal human endometrium has not been fully elucidated until recently. Frozen tissue sections taken from 22 women who underwent hysterectomy and adnexectomy for benign disease were immunostained with antibodies raised against the different NOS isoforms to investigate the presence of NOS in human endometrium. iNOS stained positive in the glandular epithelial cells of the secretory endometrium. Staining was either weak or absent in the proliferative and inactive endometrium, as well as in the oviduct and the glandular epithelium of the endocervix. The stroma remained uniformly negative. Immunoreactivity for endothelial constitutive NOS (eNOS) was confined exclusively to endothelial cells. Furthermore, epithelial cells from endometrium, oviduct and endocervix and all endothelial cells showed positive staining for reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase, which is a histochemical marker for NOS activity. Reverse transcriptase polymerase chain reaction (RT-PCR) was performed in order to assess the presence of NOS mRNA. Abundant expression of iNOS mRNA was detected in the secretory phase endometrium only. The strong expression of inducible NO synthase in human secretory phase endometrium suggests that the increased production of NO, probably induced by cytokines, may be relevant to the process of menstruation.

Presence of endothelial calcium-dependent nitric oxide synthase in breast apocrine metaplasia

Endothelial calcium-dependent nitric oxide (NO) synthase has been shown to be expressed in human malignant breast tumours, and its presence correlates with tumour grade. Moreover, NO, being synthesised in breast tumour cells, may increase tumour blood flow and promote angiogenesis. In view of these aspects, we have assessed the distribution of NO synthase within a series of benign breast tumours using a monoclonal antibody against human endothelial calcium-dependent NO synthase. Activity was predominantly localised in apocrine metaplastic cells of fibrocystic disease, as well as in endothelia throughout all tissue sections. Consistent with previous reports, no endothelial calcium-dependent NO synthase immunoreactivity was observed in poorly differentiated infiltrating duct carcinoma cells. In conclusion, expression of endothelial calcium-dependent NO synthase in human breast apocrine metaplasia may be of significance in view of the NO's vascular effects in benign breast disease.

CD40 antigen is expressed by endothelial cells and tumor cells in Kaposi's sarcoma

The CD40 antigen is a member of the tumor necrosis factor receptor/nerve growth factor receptor superfamily and is involved in cell proliferation, differentiation, and survival. Using different monoclonal antibodies, we found CD40 expression by immunohistochemistry on CD31- and CD34-positive Kaposi's sarcoma spindle cells in all tumors of 18 HIV-1 seropositive and 4 HIV-1 seronegative patients. Western blot analysis of tumor lysates detected a 48- to 50-kd glycoprotein corresponding to the CD40 antigen expressed by B lymphocytes. CD40 expression was also detectable in one of four cultures of spindle cells derived from Kaposi sarcoma tissue. Treatment of the CD40-positive spindle cells but not of the CD40-negative ones with interferon-gamma up-regulated CD40 surface expression. Besides on Kaposi sarcoma tumor cells, CD40 was distinctly present on vascular endothelial cells in areas within and adjacent to the tumors and in benign inflammatory lesions such as granulation tissue of HIV-1-negative patients. In contrast, CD34-negative endothelia of thin walled vessels, most likely lymphatics, were predominantly CD40 negative. Only faint or no CD40 expression was found on endothelial cells in normal skin. We conclude from our data that expression of the CD40 antigen by endothelial cells is up-regulated during tissue inflammation. As signaling through CD40 is able to increase cell survival, expression of CD40 by Kaposi sarcoma tumor cells might play an important role in the pathogenesis of this neoplasm.

Human melanocytes and melanoma cells constitutively express the Bcl-2 proto-oncogene in situ and in cell culture

The Bcl-2 proto-oncogene regulates cell survival by antagonizing events that lead to apoptotic cell death and has been reported to be expressed in situ in lymphoid tissues, glandular epithelium, neurons, and basal epidermal cells. When we performed immunostaining on cryostat sections of normal skin, anti-Bcl-2 reactivity was confined to scattered dendritic cells in the basal epidermal layer. Double-staining experiments showed that the Bcl-2+ cells were positive for vimentin but negative for cytokeratins, CD1a, and CD45 antigens, excluding keratinocytes and Langerhans cells as possible candidates for constitutive Bcl-2 expression. Bcl-2+ epidermal cells also reacted with the monoclonal anti-melanocyte antibody NKI/beteb, and were absent from lesional skin in vitiligo, confirming that they represented epidermal melanocytes. Western blot analysis of cultured melanocytes and melanoma cell lines revealed a 26-kd protein specifically reacting with the anti-Bcl-2 monoclonal antibody. Immunostaining of pigmented lesions revealed strong expression of Bcl-2 by five of five nevocellular nevi and seven of seven melanomas. Our observations demonstrate that, within normal human epidermis, melanocytes are the only cells that express Bcl-2 constitutively and that Bcl-2 is expressed in benign and malignant pigmented tumors of the skin in situ.