Protein patterns of benign and malignant human melanocytes show consistent changes in gene expression

For human malignant melanoma, no pattern of oncogene activation has yet been identified which consistently occurs in the malignant cells. In order to better understand the transformation process, we studied the overall gene expression at the protein level in human melanoma cells in vitro by two-dimensional gel electrophoresis. For that, four established cell lines, MEWO, M5, SKMEL13, and IGR39, were used and compared with newly established cultures of normal human melanocytes. Considerable variations in the protein patterns of the different melanoma cell lines were found, whereas the patterns of normal human melanocytes correlated fairly well with each other. With respect to the expression of single proteins, we identified four major proteins which were consistently found in cultured melanocytes and stringently repressed in the four melanoma cell lines examined. On the other hand, induction of new proteins in the different melanoma cell lines was found to be less stringent and also less uniform. We propose that malignant transformation of melanocytes may be more associated with the suppression of melanocytic proteins rather than with new expression of melanoma specific proteins.

[Pre-myopathic versus amyopathic dermatomyositis. 2 personal cases and review of the literature]

The so-called amyopathic dermatomyositis is a rare variant of dermatomyositis which has attracted increasing interest during the last years. One finds the classical signs of dermatomyositis such as periorbital edema and erythema, erythematous macular and papular lesions localized at bony prominences (so-called Gottron's papules), generalized pruritus, photosensitivity, and a cutaneous histopathologic picture compatible with skin lesions of dermatomyositis. Crucial for the diagnosis is the exclusion of myositis by clinical examination, EMG and histology. Furthermore, longterm supervision of patients is advisable in order not to miss the appearance of early signs of myositis. The longest reported follow-up of amyopathic dermatomyositis patient is 4 years; however, it cannot be excluded that these cases will eventually culminate in classical dermatomyositis. In this paper we describe two cases and discuss the differential diagnosis and therapy; also, the term "Premyopathic dermatomyositis" is proposed, to indicate that the full picture is to be expected in most cases.

Growth control of melanoma cells and melanocytes by cytokines

Aberrant proliferation of tumor cells characterizes cancer growth. Investigations of cellular growth control mechanisms have contributed to our understanding of carcinogenesis and to the identification of compounds with specific antitumor activity. Many cytokines have been found to act on melanoma tumors, either produced by the tumor cells themselves or by infiltrating host cells. Purified cytokines allowed direct comparison of the growth response between normal human melanocytes and malignant melanoma cells. The present paper summarizes results of a series of our own experiments not yet published and data from a review of the recent literature. Proliferation of normal human melanocytes is enhanced by several cytokines, including basic fibroblast growth factor (bFGF), melanoma growth stimulatory activity (MGSA), hepatocyte growth factor (HGF), and mast cell growth factor (MGF). Melanoma cells are additionally stimulated by epidermal growth factor (EGF)/transforming growth factor alpha (TGF-alpha) and nerve growth factor (NGF). Tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta 1 (TGF-beta 1), and interleukin (IL)-6 are all potent inhibitors of melanocyte growth, but they are less effective on melanoma cells or even stimulate their growth. Interferon (IFN)-alpha and IFN-gamma inhibited proliferation of melanoma cells but not of melanocytes, whereas IFN-beta showed antiproliferative effects in both cell types. These findings suggest an alteration in growth control mechanisms during melanocyte transformation and possibly play a role in melanoma pathogenesis.

Immunohistochemical analysis of chronic discoid and subacute cutaneous lupus erythematosus--relation to immunopathological mechanisms

An immunohistochemical analysis of skin biopsies was performed in 18 patients with cutaneous lupus erythematosus (LE), using the alkaline phosphatase and monoclonal anti-alkaline phosphatase method (APAAP). The study group was subdivided on the basis of clinical criteria into 10 patients with chronic discoid LE (CDLE) and eight patients with subacute cutaneous LE (SCLE). Using a panel of monoclonal antibodies the following results were obtained: (i) ICAM-1 was expressed on epidermal keratinocytes, dermal inflammatory cells, and endothelial cells in most biopsies, whereas LFA-1 was confined to the dermis. Attachments between keratinocytes or endothelial cells and activated T lymphocytes via ICAM-1/LFA-1 may be a possible mechanism of target/effector recognition in cutaneous LE. (ii) HLA-DR was expressed on epidermal keratinocytes and cells of the dermal infiltrate, but not on endothelial cells. HLA-DR+ cells probably function as antigen-presenting cells, leading to major histocompatibility complex-restricted cellular cytotoxicity in cutaneous LE. (iii) Interleukin 2 receptor expression on dermal inflammatory cells was weak, indicating non-specific activation of T lymphocytes. (iv) The dermal inflammatory cells were T lymphocytes, mainly of the helper/inducer subtype. B lymphocytes were rarely found in the dermis. In general, no significant immunohistochemical differences were found between CDLE and SCLE, suggesting that these variants represent clinical subtypes rather than different pathogenetic entities.

[Large cell anaplastic Ki-1 positive lymphoma of the skin. 5 personal cases and review of the literature]

Primary cutaneous large cell anaplastic non-Hodgkin lymphomas positive for Ki-1-antigen are rarely described. There are 100 published cases worldwide. Typically large cell anaplastic lymphomas have an inflammatory appearance, which often leads to false diagnosis and unsuccessful treatment with antibiotics. Histological examination reveals a highly malignant non-Hodgkin lymphoma. The tumour is composed of large pleomorphic lymphoid cells composed of T-cells in 80% of the cases and of B-cells in 10%. The immunological phenotype in the remaining 10% remains unclear. Crucial for the diagnosis is the expression of CD30 antigen in > 70% of the tumour cells. This article presents 5 cases of cutaneous Ki-1-positive lymphoma seen in our Berlin department during the last 10 years. In 4 patients the diagnosis was established in clinical stage I of cutaneous lymphoma without further manifestation; 1 patient had lymph node involvement and was in stage II. Total excision of the primary tumour in stage I with adjuvant polychemotherapy in stages II-IV led to complete remission in all cases. Long-term remissions were seen in case 1 (2 years) and in case 5 (1 year), whilst 2 patients showed local relapse, and 1 patient showed generalized lymphogenic and hematogenic metastasis. After repeated surgical removal or irradiation of the tumour and adjuvant polychemotherapy, further complete remission was achieved in 2 patients (up to now lasting 1 and 4 years). another patient has been in partial remission for the last 2 years. Our observations underline the high relapse rate of large cell anaplastic lymphoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Successful treatment of chronic graft-versus-host disease with extracorporeal photopheresis

A 43-year-old woman who had undergone allogeneic bone marrow transplant for chronic myeloid leukemia developed chronic GVHD. Despite cyclosporine A and low-dose glucocorticoids and later concomittent PUVA-therapy, chronic GVHD with severe sclerodermatous manifestations including joint contracture and liver damage progressed. The Karnofsky performance score dropped to under 50%. Extracorporeal photopheresis (ECP) instead of PUVA-therapy was started. To our knowledge, we here report the first case of successful treatment of extensive chronic GVHD with ECP.

Paracrine and autocrine regulation of human melanocyte and melanoma cell growth by transforming growth factor beta in vitro

It has been considered that the growth of human melanoma cells is positively and negatively regulated by transforming growth factors. To investigate further the role of transforming growth factor beta (TGF-beta) in melanoma biology, we analysed paracrine and autocrine growth regulatory properties of TGF-beta in normal human melanocytes and malignant melanoma cell lines in vitro. Exogenously added TGF-beta 1 potently inhibited normal melanocyte proliferation and DNA-synthesis in all cultures examined; in contrast, TGF-beta 1 inhibited only moderately or not at all the growth of cultured melanoma cells. Melanoma cell lines established from metastatic lesions were found to be less sensitive to TGF-beta 1 than those derived from primary melanomas. TGF-beta 1 resistance correlated with high levels of active TGF-beta secreted by metastatic cell lines. Inactivation of endogenously produced TGF-beta by neutralizing anti-TGF-beta antibody resulted in the stimulation of cell proliferation of a TGF-beta-sensitive primary melanoma cell line but not of a resistant metastatic one. These findings suggest that TGF-beta may function as a paracrine and autocrine growth inhibiting factor in the growth regulation of human melanocytic cells. The gradual loss of response of melanocytic cells to TGF-beta during malignant progression suggests that escape of melanoma cells from growth regulation by TGF-beta could be involved in melanoma oncogenesis.

Growth factors stimulate phosphorylation of CTP:phosphocholine cytidylyltransferase in HeLa cells

The effect of insulin and epidermal growth factor on the phosphorylation of CTP:phosphocholine cytidylyltransferase (EC 2.7.7.15) was investigated in HeLa cells. For the first time, cytidylyltransferase phosphorylation was shown to be influenced by growth factors in cell culture experiments. The rephosphorylation of cytidylyltransferase after an oleate-mediated dephosphorylation and translocation to membranes was increased after 2 min in the presence of insulin or epidermal growth factor by 99% and 76%, respectively, compared with controls. However, the increased phosphorylation of cytidylyltransferase did not have an effect on its subcellular distribution. Furthermore, purified cytidylyltransferase preincubated with alkaline phosphatase is a substrate for p44mapk, a member of the mitogen-activated protein (MAP) kinase family downstream of the growth factor receptors, in vitro. In accordance with the in vivo data, in vitro phosphorylation of cytidylyltransferase by p44mapk occurred after 2 min.

[Course and prognosis of subacute cutaneous lupus erythematosus. A prospective study of 34 patients]

34 patients with subacute cutaneous lupus erythematosus (SCLE) were prospectively followed up and examined twice in 1986-1989 and 1990-1991, with a minimal interval of 2 years. The findings obtained were documented in a computerized registry and were evaluated by computer-assisted analysis. Thirty-one women and three men aged 23-66 years at the time of the first documentation (FD) were included in the study. The disease had lasted an average 6.5 years (from a few months to 39 years). Prominent cutaneous manifestations of SCLE were shown by 79.4% of the patients at the first visit compared to 58.8% at the second documentation (SD), whereas the incidence of acrolocalized vasculitis increased (FD 20.6%, SD 41.2%), as did that of Raynaud phenomenon (FD 20.6%, SD 26.5%). Mild extracutaneous symptomatology was found in 70.6% (FD) and in 85.3% (SD) of the SCLE patients. Arthralgia (FD 47%, SD 61.8%) and symptoms suggesting some involvement of the peripheral or central nervous system (FD 29.4%, SD 50%) were noted most frequently. Overall, during the follow-up there was a quantitative mild increase of extracutaneous symptomatology; a significant correlation between the presence of acrolocalized vasculitis and arthralgia was found. In conclusion, the prognosis of SCLE appears rather benign; fulminant courses were not observed. However, the risk of mild systemic involvement clearly increases during the prospective course of the disease, whereby acrolocalized vasculitis can be regarded as a cutaneous marker for extracutaneous manifestations.

P53 mutation and c-fos overexpression are associated with detection of the antigen VLA-2 in human melanoma cell lines

In this study, we examined the expression of c-fos, c-myc, mutant c-Ha-ras and mutant p53 proteins in three normal human melanocyte cell lines and the following 12 melanoma cell lines: M5, Mewo, A375, Bro, Mel 2a, O-Mel II, IgR 39, SkMel-13, -19, -28 Mel-57 and NKI-4, using an immunohistochemical assay (APAAP). An effort was made to correlate oncogene expression with growth parameters, differentiation antigens (HMB-45, vla-2, k.1.2.58, HLA-DR, HLA-I), and pigmentation. All melanocyte cell lines were negative for the oncogenes examined, whereas six of the melanoma cell lines were found also positive (three for c-fos, two for c-myc, one for c-Ha-ras, and four for p53). Three melanoma cell lines expressed one oncogene and three the combination c-fos/p53. These three melanoma cell lines were positive for the "late" tumor progression marker A. 1.43 (vla-2 adhesion molecule) and negative for the differentiation marker k. 1. 2. 58. Positivity for A. 1. 43 combined with negative staining for k. 1. 2. 58 was found in six out of the 12 cell lines. The observed oncogene expression correlated neither with growth parameters nor melanin content. The present findings revealed a coexpression of mutant p53 and c-fos proteins being associated with a highly malignant phenotype in melanoma cell lines. Further studies are necessary to clarify the significance of the above findings.

[HIV-associated dermatoses and their prevalence in 456 HIV-infected patients. Relation to immune status and its importance as a diagnostic marker]

Some 456 patients with HIV-associated skin disorders were documented in the HIV follow-up clinics at the Department of Dermatology, University Medical Center Steglitz, Berlin, during the years 1982-1992. Males comprised 91% of the patients. The most important risk groups for HIV infection were homosexual and bisexual men (77.9%) and individuals with intravenous drug abuse (12.7%). The most frequent dermatological diagnoses were oral candidosis (44.5%), seborrhoeic dermatitis (38.6%), folliculitis (32.9%) and Kaposi's sarcoma (23.5%). Altogether, 138 of the patients died during the time of observation. The most frequent cause of death was disseminated Kaposi's sarcoma (26.8%). A significant proportion of the patients developed skin diseases before significant reduction of the circulating CD4+ lymphocytes. In a still satisfactory immune situation, predominantly infections of the skin with dermatophytes (tinea), human papilloma viruses (warts) and bacteria (pyodermas) were observed. A considerable number of the HIV patients who developed zoster were also still in a favourable immune status; another 50% of these cases, however, developed the disease with reduced CD4+ lymphocyte count (< 300/microliters). Skin manifestations that tended to occur later in the course of HIV infection were oral candidosis, oral hairy leukoplakia, herpes genitoanalis, mollusca contagiosa and Kaposi's sarcoma, in spite of their early appearance in some cases. In the large majority of these patients the immunological parameters were already clearly reduced. Fungal, bacterial and viral infections of the skin, especially with extended skin involvement, may manifest themselves during the early phases of HIV infection. The number and severity of the skin manifestations increase with progressing immunosuppression, and treatment is often a difficult challenge for the dermatologist.

Evidence for a complement-mediated inhibition and an antibody-dependent cellular cytotoxicity of dermal fibroblasts in alopecia areata

Immunological mechanisms have long been suggested to mediate hair loss in alopecia areata. In this process hair bulb melanocytes and dermal papilla fibroblasts are believed to be primarily involved. In the present study we further investigated the role of humoral factors in alopecia areata. Three different experiments were performed on normal human epidermal melanocytes as well as normal human dermal fibroblasts: (i) incubation with medium containing 2, 10, or 20% alopecia areata serum (n = 12 patients) for 16 h, (ii) incubation with medium supplemented with preheated alopecia areata serum (1 h at 56 degrees C) and healthy human fresh serum as a complement source (1:1) and (iii) incubation with 2, 10 or 20% alopecia areata serum but, in addition, containing peripheral blood mononuclear cells from healthy subjects (effector/target ratio, 50:1). As controls, normal human fibroblasts and normal human epidermal melanocyte cultures were also incubated with serum from healthy individuals (n = 5) under the same culture conditions. The results showed that alopecia areata serum exerted a significant stimulation of proliferation of both normal human fibroblasts (p > 0.05 at 2%, p > 0.05 at 10%, p < 0.05 at 20%), and normal human epidermal melanocytes (p > 0.05 at 2%, p < 0.05 at 10%, p > 0.05 at 20%).(ABSTRACT TRUNCATED AT 250 WORDS)

[Long-wave ultraviolet radiation (UVA) and skin cancer]

Ultraviolet light is frequently used for cosmetic tanning of the skin. UV light is known to be carcinogenic, but this is attributed predominantly to short-wavelength UV radiation (UVB). However, new data indicate a carcinogenic role for long wavelength ultraviolet light (UVA) also. In vitro studies have demonstrated DNA-damaging effects of UVA. In animals squamous cell carcinomas and melanomas were induced by UVA alone or in combination with UVB. Reference to a possible carcinogenicity of UVA may also be derived from the therapeutic application of UVA together with psoralens (PUVA). In addition, recent epidemiological studies have associated the use of sunbeds with the development of malignant melanoma. In conclusion, the carcinogenicity of UVA in humans cannot be ruled out, but requires further validation. Long and repeated UVA exposure should be discouraged, because of the far-reaching risks involved.

Progressive differentiation of human sebocytes in vitro is characterized by increasing cell size and altering antigen expression and is regulated by culture duration and retinoids

Increasing cell size, lipid accumulation, and altered antigen expression are features of sebaceous differentiation in vivo. Enhanced lipid synthesis with progressive differentiation is also present in cultured human sebocytes. This study was conducted to investigate the evolution of cell size and antigen expression of human sebocytes with progressive differentiation in vitro. Subconfluent human sebocyte cultures were examined for sebocyte differentiation evaluated on cytocentrifuge preparations by light microscopy and classified in stages according to morphological criteria described for sebocytes in vivo. Rates of 5.1 +/- 2.2% undifferentiated sebocytes, 29.2 +/- 4.9% early differentiated, 20.7 +/- 4.1% advanced differentiated, 37.6 +/- 6.4% fully differentiated, and 5.9 +/- 1.9% mature sebocytes were calculated in secondary cultures. The size of cultured sebocytes measured by computer-assisted planimetry significantly increased with progressive differentiation up to 4-5.5 times. The low rates of mature sebocytes and the only moderate increase of their size with progressive differentiation indicate an incomplete terminal differentiation in vitro. Sebocytes were subsequently stained with a series of monoclonal antibodies (mAb) to determine antigen expression using the alkaline phosphatase anti-alkaline phosphatase technique. The number of sebocytes labeled with the anti-keratin mAb CK8.12 and KL1, and the mAb 34D11 (82 kD protein) increased with progressive differentiation; significant differences were found after comparing early and advanced differentiated sebocytes. Sebocytes were positively stained with the anti-keratin mAb 6B10 (K 4), RPN1162 (K 7), CK13 (K 13), RPN1165 (K 19), CK8.60, and the mAb 115F5 (MAM-6c), OM-1 (sebaceous gland antigen), and 24F10 (basic polypeptides) only at late-stage differentiation. The expression of keratins 4, 7, 13, and 19 was confirmed by gel electrophoresis and immunoblotting. The data obtained were used to study the effects of the duration of cultivation and of the retinoids isotretinoin and tretinoin on sebocyte differentiation in vitro. Subcultivation of sebocytes upregulated, and treatment with isotretinoin but not with tretinoin downregulated labeling with mAb which recognize indicating progressive and late-stage differentiation.

[Anhidrotic ectodermal dysplasia. Disorder of the differentiation of hair follicles and sweat glands leads to abnormal keratinization]

We report on an 11-year-old female patient with anhidrotic ectodermal dysplasia (AED) showing the following characteristics: (1) reduced number of hair follicles and incomplete formation of sweat glands; (2) disturbed hair growth with shortening of anagen and anhidrosis; (3) disturbed cytokeratin expression pattern of CK 13, 14, 19 (follicular epithelium) and of CK 18 (eccrine sweat glands); (4) reduction of cystine and increase in sulphonic cysteine acid. Thus, we demonstrated pathological differentiation on the immunomorphological and on the biochemical level, leading to disturbed keratinization that could be visualized by transmission and scanning electron microscopical studies of the hair shafts. According to these findings AED is a developmental defect that involves not only incomplete formation of hair follicles and sweat glands but also a disordered differentiation and follicular keratinization with disturbed cytokeratin pattern and pathological amino acid composition of the terminal hairs produced.

Carcinoma-associated 38-kD membrane glycoprotein MH 99/KS 1/4 is related to proliferation and age of transformed epithelial cell lines

A 38-kD cell-surface glycoprotein (MH 99, KS 1/4) appears strongly elevated in epithelial malignancies, although it also occurs in a few immature, germ-cell phenotypic tissues in human epidermis. In this study, the expression and synthesis characteristics of the MH 99 antigen were examined in several transformed epithelial cell lines. Marked increase of MH 99 (by 100-200%) was found in highly proliferative cell populations, as demonstrated by radioimmunoprecipitation, fluorescence-activated cell sorter analysis, and proliferation experiments in cultures of spontaneously immortalized keratinocytes (HaCaT) squamous cell carcinoma lines (SCL 1 and SCL 2), and SV-40 transformed keratinocytes (130, 425, and HaSV). The relation of the MH 99 antigen to cell proliferation was underscored by a 70-75% decrease of synthesis in nonproliferating HaCaT cells treated with mitomycin C. Blocking of two distinct epitopes of the molecule with two different monoclonal antibodies (MH 99 and MM 104) decreased cell proliferation by approximately 25% (F = 519.6; df = 1,145; p < 0.0001), as compared to untreated cells and to cells treated with unrelated antibodies (BT 15 and J 143). Analysis of MH 99 synthesis in aging transformed keratinocytes cultured without passage revealed downregulation by approximately 50-60% after 60 d, indicating inverse correlation of the MH 99 antigen with increasing cell age. It seems, therefore, that the MH 99 antigen is directly correlated with cell proliferation and inversely correlated with increasing age of transformed epithelial cells, possibly playing an active role in the process of cell proliferation.

Ulerythema ophryogenes and keratosis pilaris in a child with monosomy 18p

We report a 13-year-old boy with deletion of the short arm of chromosome 18 and follicular, partially inflammatory, keratotic papules of the eyebrows, foreskin, and cheeks (ulerythema ophryogenes) as well as the shoulders, upper back, upper arms, and thighs (keratosis pilaris), initially diagnosed as atopic dermatitis. Over 100 patients with this genetic defect have been reported, and the 18p- syndrome is considered one of the most frequently occurring deletion syndromes. However, ulerythema ophryogenes and keratosis pilaris have not been described in any of these patients, although the association of the latter with other genetic abnormalities is well known. Keratosis pilaris is a relatively common genodermatosis of ectodermal origin, frequently occurring with ichthyosis or atopy; concomitance with ulerythema ophryogenes has also been reported. The association of chromosome 18p deletion defect and ulerythema ophryogenes may be helpful in future attempts to localize the gene defect responsible for follicular genokeratoses.

Identification of a putative membrane-interacting domain of CTP:phosphocholine cytidylyltransferase from rat liver

A putative membrane-interacting domain of CTP:phosphocholine cytidylyltransferase (CT) was identified using two peptide-specific antibodies. One antibody (SA2) was raised against the N-terminus of CT (amino acid residues 1-17) and the other antibody (SA209) against an alpha-helical domain of the enzyme (amino acid residues 247-257). Both antibodies quantitatively immunoprecipitated CT from rat liver cytosol and showed specificity towards CT when octylglucoside extracts of rat liver cytosol were assessed by Western blot analysis. However, further experiments revealed that the antibodies had different characteristics. Whereas the antibody directed against the N-terminus of CT (SA2) did not influence CT/membrane interaction, the new antibody (SA209) against the alpha-helical domain of the enzyme interfered with this interaction. Our results provide experimental evidence that the alpha-helical domain (amino acid residues 228-287) of CT may serve as a membrane-interacting domain.

[Position and recommendations of the Malignant Melanoma Committee of the German Society of Dermatology on diagnosis, treatment and after-care of malignant melanoma of the skin. Status 1993/94]

The Melanoma Committee of the German Dermatological Society has prepared this position paper on prognostic factors, classification and clinical staging of cutaneous malignant melanoma and has recommended guidelines for diagnosis, treatment and follow-up. The aim is to achieve a consensus procedure for dealing with this tumour.

Successful outcome of cryosurgery in patients with granuloma annulare

Several therapeutic methods have been employed in the management of localized granuloma annulare (GA), with varying degrees of success. We performed a prospective trial to evaluate the efficacy, cosmetic results, and safety of cryosurgical treatment in GA. Thirty-one patients with localized GA were treated by cryosurgery, using the contact method. Nitrous oxide (-86 degrees C) or liquid nitrogen (-196 degrees C) were used as refrigerants, and were applied with closed probes; each lesion was treated with one freeze-thaw cycle of 10-60 s per session. If necessary, treatment was repeated after 20-30 days. Resolution of the lesions was obtained in all patients, and in 25 of 31 patients (80.6%) they resolved after a single freeze-thaw cycle. Relapse occurred in only one of 11 patients who were followed for more than 2 years, and this occurred 16 months after treatment. Excellent cosmetic results were obtained in 14 of 28 patients who were eligible for evaluation (50%), and good results in 11 (39.3%). The cosmetic result obtained by cryosurgery with nitrous oxide was independent of the size of the lesion, whereas in the group of patients treated with liquid nitrogen a better cosmetic result was obtained with smaller lesions (comparison of lesions < or = 2.40 cm2 with those > 2.40 cm2; P = 0.04). The duration of the lesion, its location, previous treatment with another method, and the number of treatment sessions, did not have any influence on the cosmetic result. The treatment was generally well tolerated. Blister formation occurred in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Phospholipid analogue hexadecylphosphocholine inhibits proliferation and phosphatidylcholine biosynthesis of human epidermal keratinocytes in vitro

The alkylphospholipid hexadecylphosphocholine (HePC), member of a new class of antineoplastic drugs, has been previously shown to exert cytotoxic effects on neoplastic cell lines in vitro, and a selective antineoplastic activity has been reported after topical application of HePC in vivo, in particular on skin metastases of human mammary carcinomas. Preliminary observations suggest that HePC might also be beneficial in the treatment of non-neoplastic skin diseases characterized by epidermal hyperplasia such as psoriasis. Therefore, we investigated whether HePC might inhibit the proliferation of normal human keratinocytes, and whether its effects might be dependent upon the proliferative status of the treated cells. Moreover, its effects on phosphatidylcholine biosynthesis were studied in keratinocytes. HePC dose-dependently decreased cell numbers, thymidine incorporation, and protein synthesis when applied during the growth phase of keratinocytes grown in serum-free medium, with a minimal inhibitory dose of 10(-7) mol/l for thymidine incorporation, 3 x 10(-7) mol/l for cell numbers, and 10(-6) mol/l for 35S-methionine incorporation. No major differences were observed when keratinocytes were grown under high-Ca++ conditions. In contrast, slowly proliferating confluent keratinocyte cultures showed growth inhibition only after 10(-4) mol/l HePC. Phosphatidylcholine biosynthesis was dose-dependently inhibited by HePC with a half inhibitory concentration of 3 x 10(-6) mol/l, and with translocation of the rate-limiting enzyme. CTP:phosphocholine cytidylyltransferase, to the cytosol, where the enzyme is inactive. These data show a pronounced antiproliferative effect of HePC also on proliferating non-malignant keratinocytes, and are compatible with its possible action on hyperproliferative skin disorders.

Further evidence for involvement of both cell mediated and humoral immunity in generalized vitiligo

Immunohistochemical and immunoserological evidence supports the involvement of both cell-mediated and humoral mechanisms in the pathogenesis of melanocyte destruction in vitiligo. Punch biopsies from depigmented vitiliginous skin (VS), normal-looking pigmented skin (PS), and marginal skin (MS) from patients with generalized vitiligo (n = 15) were labeled with K 1.2.58, OKM1 (CD11b), Leu 11b (CD16), Leu 19 (CD56), IFN-gamma receptor, IL-2 receptor (CD25), IgG, IgM, C3c, and C3d MoAbs. In addition, in vitro effects of vitiligo sera (n = 13) on human newborn melanocytes (HMel) under different culture conditions were studied. The immunohistochemical findings showed absence of K 1.2.58+ epidermal melanocytes in VS and abnormal morphology in MS. In these areas, a few CD11b+ cells in the dermis and epidermis could be detected but no significant numbers of CD16+ or CD56+ cells were seen among the mononuclear cellular infiltrate. IL-2 and IFN-gamma receptors were clearly expressed by the cellular infiltrate. No significant deposition of complement or immunoglobulin was seen. The addition of vitiligo sera to HMel cultures induced a significant cellular proliferation. The stimulation of cell proliferation occurred regardless whether the sera were added alone or when preheated (56 degrees C for 1 hr) and then supplemented with a complement source (P < 0.01 at 2%, P < 0.001 at 10%, and P < 0.01 at 20% for sera alone) (P > 0.05 at 2%, P < 0.05 at 10%, and P < 0.01 at 20% for decomplemented sera plus complement).(ABSTRACT TRUNCATED AT 250 WORDS)

Androgens affect the activity of human sebocytes in culture in a manner dependent on the localization of the sebaceous glands and their effect is antagonized by spironolactone

To investigate the varying response of the pilosebaceous unit to androgens functional studies were performed on the effects of testosterone and 5 alpha-dihydrotestosterone on cultured human sebocytes derived from different skin regions. In addition, the effect of spironolactone on the proliferation of androgen-stimulated human sebocytes derived from facial skin was evaluated. Testosterone (10(-11) to 10(-5) M), 5 alpha-dihydrotestosterone (10(-11) to 10(-5) M) and spironolactone (10(-12) to 10(-7) M) were added for 10 days as single substances or in combinations to human sebocytes in secondary culture maintained in a serum-free medium. Cell proliferation was assessed using a fluorometric assay. Intracellular lipids were extracted from sebocytes treated with androgens (10(-7) M) for 10 days after confluency. Testosterone inhibited the proliferation of sebocytes derived from the legs with a 50%-inhibitory concentration at 10(-5) M and induced a 50% decrease of intracellular lipids. In contrast, 5 alpha-dihydrotestosterone stimulated the activity of leg sebocytes with a 50% increase of proliferation at 10(-5) M, and a 175% increase of intracellular lipids. On the other hand, the proliferation of facial sebocytes was significantly stimulated by testosterone with a 50%-stimulatory concentration at 10(-6) to 10(-5) M and mostly by 5 alpha-dihydrotestosterone with a 50% enhancement at 10(-8) to 10(-7) M. Spironolactone inhibited the proliferation of facial sebocytes in a dose-dependent manner with a 25%-inhibitory concentration at 10(-9) M. Simultaneous treatment of facial sebocytes with spironolactone and testosterone or 5 alpha-dihydrotestosterone resulted in decreased proliferation when compared to the growth obtained under androgens alone.(ABSTRACT TRUNCATED AT 250 WORDS)