Bone morphogenetic protein antagonist noggin promotes skin tumorigenesis via stimulation of the Wnt and Shh signaling pathways

Bone morphogenetic proteins (BMPs) play pivotal roles in the regulation of skin development. To study the role of BMPs in skin tumorigenesis, BMP antagonist noggin was used to generate keratin 14-targeted transgenic mice. In contrast to wild-type mice, transgenic mice developed spontaneous hair follicle-derived tumors, which resemble human trichofolliculoma. Global gene expression profiles revealed that in contrast to anagen hair follicles of wild-type mice, tumors of transgenic mice showed stage-dependent increases in the expression of genes encoding the selected components of Wnt and Shh pathways. Specifically, expression of the Wnt ligands increased at the initiation stage of tumor formation, whereas expression of the Wnt antagonist and tumor suppressor Wnt inhibitory factor-1 decreased, as compared with fully developed tumors. In contrast, expression of the components of Shh pathway increased in fully developed tumors, as compared with the tumor placodes. Consistent with the expression data, pharmacological treatment of transgenic mice with Wnt and Shh antagonists resulted in the stage-dependent inhibition of tumor initiation, and progression, respectively. Furthermore, BMP signaling stimulated Wnt inhibitory factor-1 expression and promoter activity in cultured tumor cells and HaCaT keratinocytes, as well as inhibited Shh expression, as compared with the corresponding controls. Thus, tumor suppressor activity of the BMPs in skin epithelium depends on the local concentrations of noggin and is mediated at least in part via stage-dependent antagonizing of Wnt and Shh signaling pathways.

Requirement of Dynactin p150Glued Subunit for the Functional Integrity of the Keratinocyte Microparasol

The keratinocyte microparasol, composed of a perinuclear microtubular/melano-phagolysosomal complex, protects the nucleus from UV-induced DNA damage. We have previously demonstrated that cytoplasmic dynein is the motor involved in the perinuclear-directed aggregation of phagocytosed melanosomes. Dynactin, of which p150(Glued) is the major subunit, can link directly to microtubules and links organelles to dynein at different domains. To further define the mechanism of the microparasol, we transfected siRNA targeted against p150(Glued) into human keratinocytes cultured with 0.5 mm fluorescent microspheres and performed time-lapse analysis, confocal immunolocalization, and Western immunoblotting after 24 and 48 hours. Western blots revealed a significant knockdown of the p150(Glued) subunit. The knockdown decreased p150(Glued) colocalization with microtubules and decreased perinuclear positioning of the convergent microtubular framework. It also inhibited perinuclear aggregation of phagocytosed fluorescent microspheres and reduced mean centripetal microsphere displacement. The findings provide evidence that dynactin p150(Glued) plays an important role in the functional integrity of the keratinocyte microparasol.

Cutaneous clear cell squamous cell carcinoma in situ : clinical, histological and immunohistochemical characterization

BACKGROUND

Clear cell squamous cell carcinoma in situ (SCCIS) has not been defined in the literature with respect to its clinical, histological, and immunohistochemical features.

METHODS

Nearly 1500 consecutive cases of SCCIS were assessed for percent clear cell change. The clinical features of all SCCIS with >or=10% clear cell change, including age, sex and site distribution, were compared with classical SCCIS using chi-square analysis. PAS special staining and immunohistochemical analysis with 11 cell markers were performed to characterize the clear cell of origin.

RESULTS

Eighty SCCIS cases with a spectrum of clear cell change of >or=10% were identified. Six cases with >or=80% clear cells were defined as clear cell SCCIS. The clinical features of the cases did not vary significantly from classical SCCIS. Antibodies labeling outer root sheath (ORS) cells also labeled clear cells in the cases and included K8.12 (labeling CK13 and CK16), cellular retinoic acid binding protein II, CAM 5.2 and CK15. Antibodies that did not label ORS cells, but did label eccrine glands (CK7 and CK18) or sebocytes (EMA), also did not label the cases.

CONCLUSION

Clear cell change in SCCIS is part of a spectrum which displays ORS differentiation.

Macrophage-rich epithelioid angiosarcoma mimicking malignant melanoma

BACKGROUND

Cutaneous epithelioid angiosarcoma is a type of cutaneous angiosarcoma and usually arise both on the head or neck of the elderly.

CASE REPORT

An 86-year-old male with an epithelioid angiosarcoma of the scalp that mimicked malignant melanoma.

RESULTS

A large irregular dark grey-blue plaque with an adjacent speckled tan nodule was suggestive of a primary cutaneous malignant melanoma with adjacent in-transit metastasis. Both had a well-circumscribed growth pattern and were composed of numerous large epithelioid cells with scattered severe atypia and mitoses. The tumor was positive for S-100 protein and vimentin and negative for low- and high-molecular weight cytokeratins. However, at high power, the epithelioid cells with severe atypia were negative for S-100 protein, and abundant large epithelioid macrophages were responsible for the S-100 protein positivity. The malignant tumor cells were negative for HMB-45, positive for CD31 and Factor VIII-related antigen, and focally positive for CD34. A focus of infiltrative, classical angiosarcoma with irregular vascular channels lined with plump, anaplastic endothelial cells was then found deep to the epithelioid tumor.

CONCLUSIONS

Macrophage-rich epithelioid angiosarcoma demonstrates abundant S-100 protein-positive epithelioid macrophages. This subset of epithelioid angiosarcoma may mimic malignant melanoma and may present as a pitfall in diagnosis.

Telomere-based DNA damage responses: a new approach to melanoma

Melanoma is the most fatal skin cancer, often highly resistant to chemotherapy. Here we show that treatment with an 11-base DNA oligonucleotide homologous to the telomere 3' overhang sequence (T-oligo) induces apoptosis of several established human melanoma cell lines, including the aggressive MM-AN line, whereas normal human melanocytes exposed to the same or higher T-oligo concentrations show only transient cell cycle arrest, implying that malignant cells are more sensitive to T-oligo effects. When MM-AN cells were briefly exposed to T-oligo in culture and injected into the flank or tail vein of SCID mice, eventual tumor volume and number of metastases were reduced 85-95% compared with control mice. Similarly, T-oligos administered intralesionally or systemically selectively inhibited the growth of previously established MM-AN tumor nodules in the flank and peritoneal cavity by 85 to 90% without detectable toxicity. We previously showed that T-oligos act through ATM, p95/Nbs1, E2F1, p16INK4A, p53, and the p53 homologue p73 to modulate downstream effectors and now additionally demonstrate striking down-regulation of the inhibitor of apoptosis protein livin/ML-IAP. We suggest that T-oligo mimics a physiologic DNA damage signal that is frequently masked in malignant cells and thereby activates innate cancer prevention responses. T-oligos may provide a novel therapeutic approach to melanoma.

Monitoring the 3-year efficacy of enzyme replacement therapy in fabry disease by repeated skin biopsies

The earliest clinical signs of Fabry disease often manifest as dermatologic disturbances such as angiokeratomata, hypohidrosis, acroparesthesias, and impaired thermal and vibration detection. These disturbances are caused by cellular globotriaosylceramide accumulation in the skin due to deficient lysosomal alpha-galactosidase A activity. In this histologic study, we analyzed pre- and post-treatment dermatologic biopsies from 58 Fabry patients enrolled in a 5 mo, Phase 3 double-blind, randomized, placebo-controlled trial followed by a 30 mo open label extension study of recombinant human alpha-galactosidase A (r-halphaGalA), administered i.v. at 1 mg per kg every 2 wk. Baseline evaluations revealed globotriaosylceramide in multiple dermal cell types (vascular endothelial cells, vascular smooth muscle cells, perineurium). Five months of r-halphaGalA treatment in the Phase 3 trial resulted in complete clearance of globotriaosylceramide from the superficial capillary endothelium in all treatment patients and in only 1 (3%) placebo patient (p<0.001). The placebo group achieved similar results after 6 mo of r-halphaGalA in the open label trial. The capillary endothelium remained free of globotriaosylceramide for up to 30 mo into the extension study among 39 of 40 (98%) patients who underwent biopsies. Globotriaosylceramide clearance from deep vascular endothelial cells was similarly robust. Vascular smooth muscle cells and perineurium demonstrated moderate clearance. These findings suggest that long-term treatment with r-halphaGalA may halt the progression of pathology and prevent the dermatologic disturbances in Fabry patients, and that periodic dermal biopsies can serve as a reliable monitor of sustained efficacy.

Role of cytoplasmic dynein in perinuclear aggregation of phagocytosed melanosomes and supranuclear melanin cap formation in human keratinocytes

Cytoplasmic dynein is a microtubule-associated motor molecule involved in the retrograde transport of membrane-bound organelles. To determine whether the supranuclear melanin cap of transferred, phagocytosed melanosomes in keratinocytes is associated with cytoplasmic dynein, we performed immunofluorescent confocal microscopy on human keratinocytes in situ. We identified the intermediate chain of cytoplasmic dynein by immunoblotting and examined its distribution by confocal microscopy in relation to microtubules and melano-phagolysosomes in vitro. We also used antisense and sense oligonucleotides of the cytoplasmic dynein heavy chain 1 (Dyh1) and time-lapse and microscopy. The intermediate chain of cytoplasmic dynein was identified in extracts of human foreskin epidermis and in isolated human keratinocytes. The intermediate chain localized with the perinuclear melano-phagolysosomal aggregates in vitro and the supranuclear melanin cap in situ. Antisense oligonucleotides directed towards Dyh1 resulted in dispersal of the keratinocyte perinuclear melano-phagolysosomal aggregates after 24 to 48 h, whereas cells treated with diluent or sense oligonucleotides maintained tight perinuclear aggregates. Taken together, these findings indicate that in human keratinocytes, the retrograde microtubule motor cytoplasmic dynein mediates the perinuclear aggregation of phagocytosed melanosomes, participates in the formation of the supranuclear melanin cap or "microparasol" and serves as a mechanism to help protect the nucleus from ultraviolet-induced DNA damage.

Inhibition of prostate carcinoma establishment and metastatic growth in mice by an antiangiogenin monoclonal antibody

A neutralizing monoclonal antibody (MAb) 26-2F to human angiogenin, a potent inducer of neovascularization, has been shown previously to prevent or delay the appearance of angiogenin-secreting human colon, fibrosarcoma and lung tumor cell xenografts implanted subcutaneously (s.c.) into athymic mice. In an analogous model system, we report here that the antibody also prevents the establishment of PC-3 androgen-independent human prostate cancer tumors in, on average, 40% of treated mice (p < 0.0001, survivor analysis). Intriguingly, combining MAb 26-2F together with cisplatin and suramin, 2 therapeutic agents that together showed little antitumor activity in the aforementioned model, resulted in an even greater degree of protection (71% protected, p = 0.009 compared to antibody treatment alone). This protective effect persisted several weeks after cessation of treatment. Additionally, prophylactic systemic administration of MAb 26-2F dramatically reduced by 50% the formation of spontaneous regional metastasis originating from primary growth in the prostate gland of PC-3M cells, highly metastatic variants of PC-3. Protection from metastasis was still significant when treatment with MAb 26-2F was delayed until after the primary tumor was well established. The antibody is not directly cytotoxic to either cell type, both of which secrete angiogenin in vitro and when growing as tumors in vivo, but changes the pattern of vascularity in primary tumors growing orthotopically. These findings, together with the observation that angiogenin protein and mRNA are apparently overexpressed in cancerous vs. normal human prostate tissues, demonstrate that angiogenin antagonism represents a promising new approach for preventing progression and metastasis of clinical prostate cancer.

Role of zyxin in differential cell spreading and proliferation of melanoma cells and melanocytes

Cell spreading, proliferation, and survival are modulated by focal adhesions linking extracellular matrix proteins, integrins, and the cytoskeleton. Zyxin is a focal-adhesion-associated phosphoprotein with one domain involved in the control of actin assembly and three protein-protein adapter domains implicated in the regulation of cell growth and differentiation. We characterized zyxin expression in normal human melanocytes and six melanoma cell lines in relation to cell spreading, growth, and differentiation using Western immunoblotting techniques, image analysis, flow cytometry, and confocal microscopy. We found that zyxin, focal adhesion kinase, and paxillin were significantly upregulated in melanoma cells compared to melanocytes. Zyxin expression directly related to cell spreading and proliferation and inversely related to differentiation, whereas focal adhesion kinase correlated only to cell spreading and paxillin did not significantly correlate with any of the parameters. Treatment of melanoma cells with 12-O-tetradecanoylphorbol-13-acetate downregulated zyxin expression, inhibited cell spreading and proliferation, and promoted differentiation. In contrast, 12-O-tetradecanoylphorbol-13-acetate, a mitogen for melanocytes, induced upregulation of zyxin expression in melanocytes. These findings are consistent with a role of zyxin in modulation of cell spreading, proliferation, and differentiation. Therapies directed at the downregulation of this focal adhesion phosphoprotein in melanoma cells implicate a new approach for controlling melanoma cell growth.

Prevention of human prostate tumor metastasis in athymic mice by antisense targeting of human angiogenin

PURPOSE

Angiogenin is a potent positive mediator of neovascularization, a process required for both primary tumor growth and metastasis. In the present study, the effect of a fully phosphorothioated antisense oligodeoxynucleotide, designated JF2S, targeting the AUG translation initiation codon region of human angiogenin, on human prostate tumor development and metastasis in athymic mice was examined.

EXPERIMENTAL DESIGN

JF2S was evaluated for its capacity to affect in vitro synthesis of angiogenin and subsequent tumorigenicity of transiently transfected prostate tumor cells in mice. In vivo treatment experiments were then conducted in which JF2S was used to prevent formation of tumors in an ectopic model and metastasis in an orthotopic model.

RESULTS

Transient transfection of tumor cells with JF2S inhibited both angiogenin gene expression in vitro and tumorigenicity of these transfected cells in athymic mice. In therapy experiments, local treatment with JF2S completely protected mice from developing prostate tumors after s.c. injection of PC-3 human prostate tumor cells (P < 0.0001, survivor analysis). Most importantly, systemic prophylactic administration of JF2S prevented, in 47% of mice, formation of regional iliac lymph node micrometastases arising from primary tumors growing in the more natural orthotopic prostate setting (P = 0.0003, Fisher's exact test). Furthermore, total protection from regional metastasis occurred in those mice in which JF2S treatment successfully diminished human angiogenin expression in vivo. Tumor-associated angiogenesis was also impaired by JF2S treatment. When therapy was delayed until all of the mice harbored primary tumors in the prostate, the incidence of regional metastasis was still significantly decreased (P < 0.005, survivor analysis).

CONCLUSIONS

These findings demonstrate that human prostate cancer establishment and spread in athymic mice is extremely susceptible to targeted disruption of tumor-derived human angiogenin gene expression. Therefore, angiogenin is a valid target against which to devise preventative strategies for prostate cancer metastasis.

Constitutive activation of Wnt/beta-catenin signaling pathway in migration-active melanoma cells: role of LEF-1 in melanoma with increased metastatic potential

A constitutive complex of beta-catenin and LEF-1 has been detected in melanoma cell lines expressing either mutant beta-catenin or mutant APC (Rubinfeld et al., Science, 275, 1790-1792, 1997). However, it has been recently reported that beta-catenin mutations are rare in primary malignant melanoma, but its nuclear and/or cytoplasmic localization, a potential indicator of Wnt/beta-catenin pathway activation, is frequently observed in melanoma (Rimm et al., Am. J. Pathol., 154, 325-329, 1999). In human malignant melanoma, the appearance of the tumorigenic phase represents a capacity for metastasis and is the significant phenotypic step in disease progression. Cell motility in invasive melanoma is thought to play a crucial role in metastatic behavior. In this work, we sought to determine which transcription factor of the LEF/TCF family was preferentially involved in human melanoma from different stages of tumor progression. We show that LEF-1 mRNA expression is predominant in highly migrating cells from metastatic melanomas. These actively migrating melanoma cells showed nuclear and cytoplasmic accumulation of beta-catenin and active transcription from a reporter plasmid of the LEF/TCF binding site. These results may provide a new insight into the role of the Wnt/beta-catenin signaling pathway in the tumor progression of malignant melanoma.

Selective expression of FLIP in malignant melanocytic skin lesions

FLIP (FLICE Inhibitory Protein) is a recently identified intracellular inhibitor of caspase-8 activation that potently inhibits cell death mediated by all death receptors including Fas and TRAIL. FLIP has recently been shown to favor tumor growth and immune escape in mouse tumor models. We analyzed FLIP expression by immunohistochemistry in a panel of 61 benign and malignant human melanocytic skin lesions. FLIP expression was undetectable in all but one benign melanocytic lesion (31/32, 97%). In contrast, FLIP was strongly expressed in most melanomas (24/29 = 83%). Overexpression of FLIP by transfection in a Fas- and TRAIL-sensitive human melanoma cell line rendered this cell line more resistant to death mediated by both TRAIL and FasL. Selective expression of FLIP by human melanomas may confer in vivo resistance to FasL and TRAIL, thus representing an additional mechanism by which melanoma cells escape immune destruction.

Expression of PGP 9.5 in granular cell nerve sheath tumors: an immunohistochemical study of six cases

BACKGROUND

Protein gene product 9.5 (PGP 9.5) is expressed in brain at 20 to 50 times the levels detected in other organs. Immunohistochemical studies reveal this protein is localized to both central and peripheral neurons. Recently, PGP 9.5 is reported to be a useful marker for cellular neurothekeomas. Herein we test whether PGP 9.5 is a new marker for granular cell nerve sheath tumors.

MATERIAL AND METHODS

An immunohistochemical analysis for PGP 9.5 expression was carried out on all cases with the diagnosis of granular cell nerve sheath tumor seen over a 2-year period. In addition, we compared expression of PGP 9.5 with other accepted markers for neuroectodermal tumors including anti-S-100 protein and NKI/C3 monoclonal antibodies.

RESULTS

Six granular cell nerve sheath tumors were diagnosed in over 80,000 dermatopathology specimens in the two-year period. These cases were all positive for PGP 9.5 as well as for S-100 protein and NK1/C3.

CONCLUSION

These findings identify PGP 9.5 as a new immunohistochemical marker for use in the diagnosis of granular cell tumors. They also strengthen the histogenetic relationship between granular cell nerve sheath tumors and tumors of Schwann cell or perineurial origin.

Changes in cellular motility and cytoskeletal actin in fibroblasts from patients with chronic venous insufficiency and in neonatal fibroblasts in the presence of chronic wound fluid

PURPOSE

Fibroblasts (fb) play an important role in wound healing involving motility, contraction, fibrosis, and expression of the cytoskeletal protein alpha-smooth muscle actin (alpha-sma). Patients with chronic venous insufficiency (CVI) are known to have dermal changes and impaired venous ulcer healing. To investigate whether these dermal-fb have an altered ability to migrate and whether chronic wound fluid from venous ulcers alters neonatal fb motility, we examined cell migration and alpha-sma.

METHODS

Fibroblasts were cultured from the margin of venous ulcers (du-fb, n = 4, CEAP 6), from patients with venous reflux without ulcer (dr-fb, n = 5, CEAP 2), and from the ipsilateral thigh of the same patients with (pu-fb) and without (pr-fb) ulcer, respectively. The abbreviations used are p and d, which represent proximal and distal, respectively; u and r represent ulcer and reflux, respectively. Neonatal foreskin fibroblasts (nf-fb) were exposed to chronic venous ulcer wound fluid (CVUWF, 300 microg protein/mL, n = 3) or bovine serum albumin (BSA, control). Fibroblast motility was determined by means of time-lapse photo-images, and the rate (micrometer per hour) was calculated. Immunohistochemistry for alpha-sma was analyzed with confocal laser microscopy.

RESULTS

The rate of motility (micrometer per hour +/- SEM) was decreased for both du-fb (11.4 +/- 0.7) and dr-fb (13.8 +/- 0.6), when compared with pu-fb (21.9 +/- 0.9) and pr-fb (24.7 +/- 1.1), respectively. The motility rate for nf-fb was lower in CVUWF (24.7 +/- 2.0) than in BSA (37.1 +/- 6.7). An elevated level of microfilament bundles of alpha-sma for both du-fb and dr-fb, compared with those of pu-fb and pr-fb, and also in nf-fb treated with CVUWF was demonstrated by means of immunohistochemistry.

CONCLUSION

These data demonstrate a reduced motility in the dermal fb of patients with CVI. Patients with reflux disease without ulcer are predisposed to these changes. Furthermore, it appears that CVUWF causes changes in motility and alpha-sma expression in nf-fb as demonstrated in du-fb. These findings suggest that reduced motility and CVUWF, representing the microenvironment of venous ulcers, play a significant role in impaired wound healing.

Intra-epidermal and intra-dermal sebocrine adenoma with cystic degeneration and hemorrhage

BACKGROUND

The ducts of eccrine glands may give rise to intra-epidermal, confluent epithelial and intra-dermal adenomas known as hidroacanthoma simplex, eccrine poroma, and dermal duct tumor, respectively. An apocrine and sebaceous counterpart of the eccrine poroma has been described by several authors as adnexal, poroma-like adenoma with apocrine and sebaceous differentiation or sebocrine adenoma.

METHODS

Using clinical history and routine histologic techniques, we describe a new lesion with features similar to sebocrine adenoma but representing the intra-epidermal and intra-dermal counterparts with cystic degeneration and hemorrhage. Briefly, an 84-year-old female presented with a 6 mm dark tan papule on the neck that clinically appeared as an unusual macular seborrheic keratosis with underlying hemorrhage.

RESULTS

Histopathological examination showed a benign dermal cystic appendage tumor with pale polygonal cells, occasional non-keratinizing ducts, sebaceous differentiation and central hemorrhage with fibrin deposits. Serial sections did not reveal any epidermal connection. However, epithelioid cells with large nuclei in an intra-epidermal pagetoid pattern were focally seen.

CONCLUSION

These findings represent a new cystic, hemorrhagic variant of sebocrine adenoma.

Altered basic fibroblast growth factor expression in common epidermal neoplasms: examination with in situ hybridization and immunohistochemistry

BACKGROUND

The fibroblast growth factor family consists of acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF), and Kaposi fibroblast growth factor (kFGF). The distribution of these growth factors in skin disease has not been determined.

OBJECTIVE

The purpose of this study was to determine the distribution of these growth factors in keratinocytic lesions and normal skin.

METHODS

Skin sections from common disorders of keratinocytes were examined by in situ hybridization with specific probes for aFGF, bFGF, and kFGF, and immunohistochemistry.

RESULTS

Of the growth factors studied, only bFGF was present in skin. bFGF messenger RNA was highly expressed in both normal epidermis and benign and malignant epithelial neoplasms. In normal skin, bFGF was expressed predominantly in a suprabasal fashion, whereas in epithelial neoplasms, homogeneous high-level expression of bFGF was observed.

CONCLUSION

bFGF is the primary member of the fibroblast growth factor expressed in the skin. The source of synthesis of bFGF is keratinocytes. Immunoreactivity for bFGF appears to be primarily confined to upper layers of the epidermis in normal skin, but is expressed at all layers of the epidermis in both benign and malignant neoplastic conditions. Genetic changes that promote epithelial tumors may also promote translation of bFGF messenger RNA into protein. Specific inhibition of bFGF activity may have application in the treatment of common skin diseases.

Role of cytoplasmic dynein in melanosome transport in human melanocytes

Cytoplasmic dynein is a microtubule-associated retrograde-directed motor molecule for transport of membrane-bound organelles. To determine whether cytoplasmic dynein is expressed in melanocytes, we performed reverse transcriptase polymerase chain reaction using melanocyte cDNA and primers complementary to human brain cytoplasmic dynein heavy chain. A polymerase chain reaction product of the expected molecular size was generated and the identity was confirmed by sequence analysis. Western blotting of total melanocyte proteins reacted with an anti-intermediate chain cytoplasmic dynein antibody identified the appropriate 74 kDa band. To determine whether cytoplasmic dynein plays a role in melanosome transport, duplicate cultures were treated with cytoplasmic dynein antisense or sense (control) oligodeoxynucleotides and the cells were observed by high-resolution time-lapse microscopy, which allows visualization of melanosomal aggregates and individual melanosomes. Antisense-treated melanocytes demonstrated a strong anterograde transport of melanosomes from the cell body into the dendrites, whereas melanosome distribution was not affected in sense-treated melanocytes. To determine whether ultraviolet irradiation modifies cytoplasmic dynein expression, melanocyte cultures were exposed to increasing doses of solar-simulated irradiation, equivalent to a mild to moderate sunburn exposure for intact skin. Within 24 h, doses of 5 and 10 mJ per cm2 induced cytoplasmic dynein protein, whereas doses of 30 mJ per cm2 or more were associated with decreased levels of cytoplasmic dynein compared with sham-irradiated controls. Our data show that cytoplasmic dynein participates in retrograde melanosomal transport in human melanocytes and suggest that the altered melanosomal distribution in skin after sun exposure is due, at least in part, to decreased cytoplasmic dynein levels resulting in augmented anterograde transport.

Kinesin participates in melanosomal movement along melanocyte dendrites

Movement of melanosomes along melanocyte dendrites is necessary for the transfer of melanin pigment from melanocytes to basal and suprabasal keratinocytes, an event critical to epidermal photoprotection and maintenance of normal skin color. Recent murine data suggest that in melanocyte dendrites the microtubule-associated melanosome movement is bidirectional and that actin-associated myosin V secures the peripheral melanosomes, preparing them to be transferred to surrounding keratinocytes. We now report that human melanocytes express high levels of kinesin, a molecule that participates in microtubule-associated transport of organelles in other cell types, and that ultrastructurally kinesin molecules are closely associated with melanosomes. To determine whether kinesin participates in melanosomal transport, cultured melanocytes were treated with sense or antisense oligonucleotides complementary to kinesin heavy chain sequences. Antisense oligonucleotides decreased kinesin protein levels and inhibited the bidirectional movement of the melanosomes, promoting their backward movement. Furthermore, guinea pigs were exposed to ultraviolet B irradiation, known to enhance transport of melanosomes from melanocytes to epidermal keratinocytes, and then were treated with kinesin sense or antisense oligonucleotides. The areas that were treated with kinesin antisense oligonucleotides showed significantly less pigmentation clinically and histologically than control (sense) oligonucleotide-treated areas. As observed ultrastructurally, in antisense-treated areas melanosomes remained in melanocyte dendrites but over several days were not transferred to the surrounding keratinocytes. Our study supports a major role for kinesin in microtubule-associated anterograde melanosomal transport in human melanocyte dendrites.

Zyxin redistributes without upregulation in migrating human keratinocytes during wound healing

Cell migration, growth, and survival is modulated by focal adhesions linking extracellular matrix proteins, cell adhesion molecules, and the cytoskeleton. Zyxin is a focal adhesion phosphoprotein that shares homology with Listeria ActA protein in promoting actin filament assembly; it also has specialized protein-protein interface domains implicating an important role in cell growth and differentiation. We investigated the distribution of zyxin in normal and migrating human keratinocytes in wounds in vitro and in situ using confocal laser microscopy. Zyxin expression in high-density nonmigrating keratinocytes versus low-density migrating keratinocytes was determined by western immunoblotting and time lapse image analysis. In normal epidermis, zyxin exhibited a punctate staining pattern throughout the cytoplasm and was excluded from the intercellular spaces. In wounds, the punctate staining also localized in the edge of the migrating keratinocyte sheets; however, intercellular spaces were absent. Likewise, in vitro keratinocytes showed punctate staining throughout the cytoplasm. Migrating cultured keratinocytes next to wounds, however, had large focal contacts in the cell periphery where actin bundles converged at focal adhesions. Western immunoblots and confocal experiments with protein synthesis inhibition by cycloheximide confirmed that this difference in distribution of zyxin in migrating versus nonmigrating keratinocytes is due to the redistribution and not upregulation of zyxin. The abundance of zyxin and its relative change in distribution from normal to migrating keratinocytes in wounds is consistent with its role in cytoskeletal organization of actin bundles.

CD44 variant isoform CD44v10 expression of human melanoma cell lines is upregulated by hyaluronate and correlates with migration

CD44, a multifunctional adhesion receptor involved in cell-cell and cell-matrix interactions, plays an important role in the local progression and metastasis of malignant tumours. We investigated relative CD44 variant isoform mRNA expression in six human melanoma cell lines and determined cell migration on hyaluronic acid (HA) coated substrates. Haematopoietic form (CD44H) mRNA expression increased in all melanoma cell lines after plating on HA, whereas the relative CD44 variant exon 10 (CD44v10) mRNA expression increased in only three of the cell lines. Cell migration rates increased on substrates coated with HA in the three CD44v10-positive cell lines, whereas the three CD44v10-negative cell lines showed no modification in migration rates. Immunofluorescent labelling of CD44v10 revealed increased expression with plaques localized to the periphery of cells. Cell lines with increased relative CD44v10 expression exhibited significantly higher mean migration rates on HA. These results indicate that CD44v10 expression functionally relates to melanoma cell migration and suggest that interaction between CD44v10 and HA plays a role in the variable tissue invasion and aggressiveness of different melanoma clones.

Treatment of benign and atypical nevi with the normal-mode ruby laser and the Q-switched ruby laser: clinical improvement but failure to completely eliminate nevomelanocytes

OBJECTIVE

To evaluate the effect of normal-mode and Q-switched ruby laser light (694 nm) on nevomelanocytes of benign, atypical, and congenital nevi.

DESIGN

Half of the lesion of each of 31 nevi was treated with either the Q-switched ruby laser or the normal-mode ruby laser or both; the other half of the lesion was covered with aluminum foil and was not treated.

SETTING

A university-affiliated, hospital-based laser center.

PATIENTS

Sixteen patients with a total of 31 melanocytic nevi were enrolled in the study.

INTERVENTIONS

All nevi were evaluated by at least 2 dermatologists to assess the degree of clinical atypia. Photographs were taken before and immediately after treatment and at each follow-up visit. The digital imaging system was used to evaluate the number of melanocytes in a measured length of basement membrane zone.

MAIN OUTCOME MEASURE

Three individual readings (number of melanocytes per unit length) were taken on both the control and treated halves and then compared to quantitate treatment effect. All analyses used averages from 3 measurements. A Student paired t test was used to compare the treated and untreated sides.

RESULTS

Sixteen (52%) of the nevi showed a clinically visible decrease in pigment on the treatment side at the 4-week follow-up visit.

CONCLUSION

No lesions had complete histologic removal of all nevomelanocytes. Therefore, 1 or 2 laser treatments are not sufficient to cause complete removal of a lesion either clinically or histologically.

Clioquinol-zinc chelate: a candidate causative agent of subacute myelo-optic neuropathy

BACKGROUND

5-chloro-7-iodo-8-hydroxyquinoline (clioquinol) was used clinically three decades ago as an oral antiparasitic agent and to increase intestinal absorption of zinc in patients with acrodermatitis enteropathica, a genetic disorder of zinc absorption. Use of clioquinol was epidemiologically linked to subacute myelo-optic neuropathy (SMON), characterized by peripheral neuropathy and blindness, which affected 10,000 patients in Japan. Discontinuation of oral clioquinol use led to elimination of SMON, however, the mechanism of how clioquinol induces neurotoxicity is unclear.

MATERIALS AND METHODS

We tested the effect of clioquinol-metal chelates on neural crest-derived melanoma cells. The effect of clioquinol chelates on cells was further studied by electron microscopy and by a mitochondrial potential-sensitive fluorescent dye.

RESULTS

Of the ions tested, only clioquinol-zinc chelate demonstrated cytotoxicity. The cytotoxicity of clioquinol-zinc chelate was extremely rapid, suggesting that its primary effect was on the mitochondria. Electron microscopic analysis demonstrated that clioquinol-zinc chelate caused mitochondrial damage. This finding was further confirmed by the observation that clioquinol-zinc chelate caused a decrease in mitochondrial membrane potential.

CONCLUSIONS

We demonstrate that clioquinol, in the presence of zinc, is converted to a potent mitochondrial toxin. The phenomenon of clioquinol mediated toxicity appears to be specific to zinc and is not seen with other metals tested. Since clioquinol has been shown to cause increased systemic absorption of zinc in humans, it is likely that clioquinol-zinc chelate was present in appreciable levels in patients with SMON and may be the ultimate causative toxin of SMON.

Pathologic parameters in the diagnosis and prognosis of primary cutaneous melanoma

Significant progress has been made in the last 10 years on the identification of histologic parameters that are independent predictors of melanoma prognosis, immunohistochemical markers of cells of melanocytic origin and changes in adhesion molecules, cytoskeletal proteins, growth factor receptors, cell signaling, and nuclear proliferation proteins associated with tumor progression. Histologic criteria may never be completely sufficient to predict behavior accurately, because the fundamental change that renders a cell aggressive may not be morphologically reflected and may require immunohistochemical or other molecular markers to establish behavior. To date, it is humbling that no immunohistochemical or molecular marker provides a greater predictable value for aggressive behavior than does the simple calibrated ocular micrometer to measure tumor thickness. Nevertheless, development of multiple histologic parameters with the concept of nontumorigenic RGP and tumorigenic VGP provides a reliable statistical model to predict metastases. Fortunately, nontumorigenic RGP melanomas with greater than 75% regression are rare. Thus, individual patients with melanoma without regression and without the tumorigenic VGP can be given reasonable assurance of 100% survival. Nevertheless, this assurance is based on a statistical model with a finite population studied. Additional studies are needed to confirm this model, as well as more definitive markers to precisely predict outcome for those individuals with tumorigenic VGP melanoma.

Curcumin is an in vivo inhibitor of angiogenesis

BACKGROUND

Curcumin is a small-molecular-weight compound that is isolated from the commonly used spice turmeric. In animal models, curcumin and its derivatives have been shown to inhibit the progression of chemically induced colon and skin cancers. The genetic changes in carcinogenesis in these organs involve different genes, but curcumin is effective in preventing carcinogenesis in both organs. A possible explanation for this finding is that curcumin may inhibit angiogenesis.

MATERIALS AND METHODS

Curcumin was tested for its ability to inhibit the proliferation of primary endothelial cells in the presence and absence of basic fibroblast growth factor (bFGF), as well as its ability to inhibit proliferation of an immortalized endothelial cell line. Curcumin and its derivatives were subsequently tested for their ability to inhibit bFGF-induced corneal neovascularization in the mouse cornea. Finally, curcumin was tested for its ability to inhibit phorbol ester-stimulated vascular endothelial growth factor (VEGF) mRNA production.

RESULTS

Curcumin effectively inhibited endothelial cell proliferation in a dose-dependent manner. Curcumin and its derivatives demonstrated significant inhibition of bFGF-mediated corneal neovascularization in the mouse. Curcumin had no effect on phorbol ester-stimulated VEGF production.

CONCLUSIONS

These results indicate that curcumin has direct antiangiogenic activity in vitro and in vivo. The activity of curcumin in inhibiting carcinogenesis in diverse organs such as the skin and colon may be mediated in part through angiogenesis inhibition.

In situ and in vitro expression of protein kinase C alpha in human melanocytes

Protein kinase C (PKC) is a multigene family of at least 12 isoforms involved in the transduction of extracellular signals. We investigated whether PKC-alpha, a major isoform known to be relatively abundant in brain tissue, is increased in human melanocytes relative to keratinocytes in vitro and in situ. Immunohistochemical staining for PKC-alpha in frozen neonatal human foreskin exhibited intermittent 2-3 + staining along the basal cell layer consistent with melanocytes, and 0-1 + staining of keratinocytes (on a scale of 0-3). Microscopic densitometry of the intermittent cellular staining was at least 3-fold greater than that of adjacent keratinocyte cell cytoplasm. Sequential frozen sections revealed similar intermittent cell staining with PKC-alpha and Mel-5 (tyrosinase related protein-1), known to specifically react with melanocytes. Northern blot analysis with a specific cDNA probe for PKC-alpha showed strong PKC-alpha mRNA expression in cultured melanocytes, whereas PKC-alpha mRNA in cultured non-stratifying keratinocytes was expressed at low levels. Western blot analysis revealed a prominent PKC-alpha band at approximately 80 kDa in melanocytes as opposed to a weak band in keratinocytes. Densitometry of the northern and western blots revealed that melanocytes had at least 10-fold more PKC-alpha mRNA and approximately 6-fold more PKC-alpha protein expression than keratinocytes. Total PKC activity measured in vitro revealed that melanocytes had 5-fold more activity than keratinocytes. The marked difference in melanocyte and keratinocyte expression of PKC-alpha provides further evidence for cell type specificity in the balance of PKC-alpha expression and may implicate differential PKC isoform signaling pathways in neuro-ectodermally derived cells.

Characterization of interleukin-1 alpha-induced melanoma cell motility: inhibition by type I and type II receptor-blocking monoclonal antibodies

Interleukin-1 alpha (IL-1 alpha) induces cell motility in a variety of benign cell types and in some but not all malignant cell lines in vitro. This study characterizes the IL-1 alpha-induced motility of an aggressive human melanoma cell line that expresses both type I and type II IL-1 receptors. We tested the effect of monoclonal antibodies including function-blocking moAbs against the type I and type II IL-1 receptors on melanoma cell motility to determine which receptor is involved in signal transduction of IL-1 alpha-induced melanoma cell motility. IL-1 alpha significantly increases MM-RU melanoma cell migration in a dose-dependent manner using modified Boyden chamber assays at concentrations 10 to 100 times less than concentrations that significantly inhibit cell growth. Computer-assisted time-lapse image analysis reveals that the motility is inhibited in a dose-dependent manner by neutralizing antibodies against IL-1 alpha. Function-blocking monoclonal antibodies against either type I or type II IL-1 receptors show a significant inhibition of cytokine-induced enhanced cell migration. When both the anti-IL-1 receptor antibodies are added together, the motility-response is completely blocked to control levels. Taken together the data indicate that the IL-1 alpha-induced motility of MM-RU melanoma cells is mediated through both type I and type II IL-1 receptors. The significant inhibition of motility by neutralizing IL-1 alpha or blocking either one or both of the IL-1 receptors indicates an integration of IL-1-induced signals in the induction of melanoma cell migration.

Treatment of small nevomelanocytic nevi with a Q-switched ruby laser

BACKGROUND

Small nevomelanocytic nevi are common and some are of cosmetic concern. Conventional therapy may cause a scar or permanent hypopigmentation.

OBJECTIVE

Our purpose was to determine whether selective photothermolysis of pigmented cells by Q-switched ruby laser treatment removes small nevomelanocytic nevi in a nonscarring fashion.

METHODS

Twelve patients with 18 small nevomelanocytic nevi were treated with a Q-switched ruby laser (694 nm, 28 nsec) at fluences of 8 J/cm2. Biopsy specimens were obtained after treatment at varying time intervals.

RESULTS

Twelve lesions (67%) showed a complete response and six lesions (33%) had a partial response. The only adverse sequela observed was mild fibrosis of the papillary dermis, without loss of papillary architecture.

CONCLUSION

The Q-switched ruby laser is effective in removing small melanocytic nevi. However, some might recur depending on the depth of the nevomelanocytic nests.

Effects of thallium ion on cellular components of the skin

Thallium salts have been employed by dermatologists to cause depilation, and dermatologic features are prominent in thallium overdose. These features include alopecia and follicular hyperkeratosis. Administration of thallium to pregnant animals results in limb deformities, similar to those seen after thalidomide embryopathy. These findings suggest that thallium may act on keratinocytes, melanocytes, and endothelial cells. We show that thallium exerts pleiotropic effects on proliferation, cell shape and motility of multiple cell types. These findings may help explain the clinical findings of thallotoxicosis.

Clinical and histological responses of congenital melanocytic nevi after single treatment with Q-switched lasers

BACKGROUND

Laser irradiation of congenital melanocytic nevi is a controversial treatment. Recurrence of lesions after laser treatment appears to be the rule, and the effects of laser irradiation on cellular biological behavior and the possible mutagenic responses of nevomelanocytes that have received nonlethal doses of irradiation are still unclear. Without treatment, there is an increased potential for malignant degeneration over a life-time. The purpose of this study was to examine the effects of Q-switched lasers on congenital nevi and to explain the mechanism(s) behind the response of the nevi to laser treatment. Five congenital nevi were divided into 3 equal parts: 1 part was treated with the Q-switched ruby laser at a wavelength of 694 nm, 1 part was treated with the Q-switched neodymium: YAG laser at a wavelength of 1064 nm, and 1 part was left untreated to serve as control. At intervals ranging from 3 days to 3 months after laser irradiation, the lesions were excised and evaluated by routine staining. This clinical study was conducted entirely at the Massachusetts General Hospital Dermatology Laser Center, Boston, Mass.

OBSERVATIONS

Both the superficial and the deep portions of the congenital melanocytic nevi were affected by the 2 lasers, as evidenced by macroscopic inspection as well as microscopic evaluation. However, the Q-switched laser treatment did not destroy all nevomelanocytes, particularly in the deeper, less pigmented portions of the lesions.

CONCLUSIONS

Both the Q-switched ruby laser and the neodymium: YAG laser often removed only the superficial portion of the congenital melanocytic nevi. The Q-switched ruby laser (694 nm) appeared to be more effective in removing nevomelanocytes than the Q-switched neodymium: YAG laser (1064 nm).

Oncogenic H-ras stimulates tumor angiogenesis by two distinct pathways

The switch from a quiescent tumor to an invasive tumor is accompanied by the acquisition of angiogenic properties. This phenotypic change likely requires a change in the balance of angiogenic stimulators and angiogenic inhibitors. The nature of the angiogenic switch is not known. Here, we show that introduction of activated H-ras into immortalized endothelial cells is capable of activating the angiogenic switch. Angiogenic switching is accompanied by up-regulation of vascular endothelial growth factor and matrix metalloproteinase (MMP) bioactivity and downregulation of tissue inhibitor of MMP. Furthermore, we show that inhibition of phosphatidylinositol-3-kinase leads to partial inhibition of tumor angiogenesis, thus demonstrating that activated H-ras activates tumor angiogenesis through two distinct pathways. Finally, we show evidence for two forms of tumor dormancy.

Attachment, spreading and migration of melanoma cells on vitronectin. The rôle of alpha V beta 3 and alpha V beta 5 integrins

Recent in situ studies suggest the alpha V beta 3 integrin is a tumour progression marker in melanoma. We analyzed 5 human melanoma cell lines for their expression of the vitronectin binding alpha V beta 3 and alpha V beta 5 integrins using flow cytometry. The role of these receptors in cell attachment, spreading and migration was investigated using attachment assays, video time lapse spreading and migration assays and with function blocking monoclonal antibodies. Cell lines derived from later stages of tumor progression exhibited high levels of alpha V beta 3 expression, whereas no similar correlation with alpha V beta 5 expression was identified. Cell attachment, spreading and migration response on vitronectin correlated well with the expression level of the alpha V beta 3 but not the alpha V beta 5 vitronectin receptor. Blocking of the alpha V beta 3 integrin resulted in a significant decrease in cell attachment, spreading and motility whereas the function blocking antibody against the alpha V beta 5 integrin only inhibited cell attachment in cell lines with the highest level of expression of this integrin. Taken together, our study indicates that the level of expression of the alpha V beta 3 and alpha V beta 5 integrins is heterogeneous in melanoma cell lines and that the alpha V beta 5 integrin, if present, may function only during the initial cell attachment whereas the alpha V beta 3 plays an important role in cell spreading and cell migration as well.

In situ distribution of integrin alpha 2 beta 1 and alpha-actinin in melanocytic proliferations

Integrin alpha 2 beta 1 is a transmembrane protein receptor for collagen and laminin previously reported as a melanoma tumor progression antigen. alpha-Actinin is an actin-binding protein reported to interact with the cytoplasmic domain of the beta 1-integrin chain of alpha 2 beta 1. In vitro, both alpha 2 beta 1 and alpha-actinin play a role in melanoma cell motility. In turn, increased melanoma cell line motility (measured as mean migration rates), correlates with metastasis. To determine the in situ distribution of these proteins, we used monoclonal antibodies directed against the alpha 2-integrin subunit of alpha 2 beta 1 and alpha-actinin on frozen sections of 33 melanocytic proliferations, which included dermal nevi, primary melanomas, and metastatic melanomas. We found that the superficial portion of all of the melanocytic proliferations tested stained for alpha-actinin. In benign nevi and superficial spreading melanoma, there was a notable loss of staining for alpha-actinin in the cells in the deep reticular dermis. In contrast, alpha-actinin was present on almost all of the tumor cells in the nodular melanomas and the melanoma metastases. Tumors stained either uniformly positive or uniformly negative for alpha 2 beta 1; the expression of this protein correlated with the later stages of melanoma progression. Our findings suggest that alpha-actinin protein levels initially decrease and then increase during melanocytic tumor progression, whereas the alpha 2 subunit protein appears in the later stages of melanoma progression. The variable distribution of these proteins is evidence for the differential adhesive and motile properties of subpopulations of cells in melanocytic proliferations.

Decreased ET(B) receptor expression in human metastatic melanoma cells

In this study, we examined the endothelin (ET) receptor subtype involved in mitogenic signaling in human primary and metastatic melanoma cell lines. In a reverse transcriptase-polymerase chain reaction (RT-PCR) study, ET(B) mRNA expression in metastatic melanoma cells was decreased from that of primary melanoma. Only RPM-EP, a primary recurrent melanoma cell line, showed strong ET(A) mRNA expression. ET-1 and ET-3 stimulated DNA synthesis of primary and recurrent cutaneous melanoma cells in serum-deprived cultures. The growth response to ET-1 in metastatic melanoma cells was decreased from that in primary melanoma cells. [125I]-IRL-1620 binding to PM-WK, a primary melanoma cell line, was significantly blocked by excessive amounts of unlabeled BQ-788. [125I]-IRL-1620 binding to metastatic melanoma cells was significantly decreased from that of primary melanoma cells. From these results, we conclude that the mitogenic effects of ET in human primary melanoma are mainly mediated through ET(B) receptors and that down-regulation of ET(B) receptors causes the decreased growth response of ET-1 in metastatic melanoma cells.

Interleukin-2 promotes the motility of dendritic cells and their accumulation in lung and skin

Dendritic cells (DC) play a critical role as antigen-presenting cells in vivo. It has previously been shown that DC accumulate in the lung in response to parenteral injections of IFN-gamma. In the current paper, we report that rat DC express the interleukin-2 receptor (IL-2R) alpha-chain (OX-39) and display enhanced motility in response to IL-2 in Boyden chamber and video time-lapse microscopy assays. Increased motility was specifically inhibited by pretreating DC with OX-39 (anti-IL-2R) but not OX-22 (anti-CD45RC), an isotype-matched murine monoclonal antibody. The intratracheal injection of IL-2 increased the number of OX-6+ dendritic cells located around pulmonary venules and in the lung interstitium. When IL-2 was injected into the footpad of the rat. DC were increased around dermal venules at 24 h. This effect was blocked by the parenteral injection of anti-OX-39. We conclude that IL-2 is a potent enhancer of DC motility and may cooperate with other T helper(h)-1 proinflammatory cytokines in attracting DC to sites of inflammation.

Modulation of alpha 4 beta 1 and alpha 5 beta 1 integrin expression: heterogeneous effects of Q-switched ruby, Nd:YAG, and alexandrite lasers on melanoma cells in vitro

BACKGROUND AND OBJECTIVE

Integrins of the beta 1 family are cellular adhesion molecules that play an important role in cell attachment and migration by interacting with extracellular matrix molecules. Agents such as hormones, cytokines, and ultraviolet radiation have all been shown to have an integrin modulating potential. The present study indicates that radiation of Q-switched lasers is also able to induce transient changes in integrin expression levels on human melanoma cells in vitro.

STUDY DESIGN/MATERIALS AND METHODS

Radiation from Q-switched Ruby (694 nm), Alexandrite (755 nm), and Nd:YAG laser (1,064 nm) with fluences comparable to those that are generally used in treating dermatologic lesions were used to irradiate a subconfluent layer of human melanoma cells. After fixed time intervals, the cells were harvested either to analyse the integrin expression by flow cytometry or to investigate changes in cell attachment, spreading, and migration.

RESULTS

It was established that all three types of laser were able to cause a significant downregulation of both the alpha 4 and the common beta 1 integrin subunit. The Alexandrite and Ruby lasers also induced a decrease in alpha 5 expression; however, the cells treated with the Nd:YAG laser showed a marked upregulation of the alpha 5 subunit. The expression of the other beta 1 integrin subunits was shown to be unaltered after laser treatment. Downregulation of the alpha 4 upregulation of the alpha 5 integrin subunit expression resulted in, respectively, decreased and increased attachment and spreading on fibronectin, the extracellular matrix ligand for both the alpha 4 beta 1 and alpha 5 beta 1 integrins. Marked upregulation of the alpha 5 subunit also resulted in a higher migration rate.

CONCLUSION

Taken together, these results show that nonlethal doses of Q-switched laser radiation are able to induce changes in cellular behavior in vitro by modulating the integrin expression pattern.

Focal adhesion kinase (p125FAK) expression correlates with motility of human melanoma cell lines

Focal adhesion kinase (p125FAK), a recently characterized protein localized within focal adhesion plaques, is believed to play a role in extracellular matrix-integrin-mediated signal transduction involving cytoskeletal proteins. We studied p125FAK expression, distribution, and relation to cell migration in six human melanoma cell lines. Western blot analysis detected differential expression of p125FAK among these lines that was directly proportional to the amount of phosphorylated p125FAK. Time-lapse image analysis of the cell lines exhibited 10-fold differences in the mean migration rates on fibronectin-coated substrates. Regression analysis revealed that p125FAK expression correlated significantly with mean migration rate in the six melanoma lines tested. Double immunofluorescent labeling for p125FAK and actin in these lines demonstrated p125FAK plaques that were localized to actin stress-fiber termination sites in the periphery of cells. The number of p125FAK plaques in the melanoma cell lines was heterogeneous, but the cell lines with more p125FAK plaques per cell exhibited significantly higher mean migration rates on fibronectin as compared with cell lines with fewer p125FAK plaques per cell. The findings support the hypothesis that focal adhesion tyrosine kinase modulates cytoskeletal function during melanoma cell migration on fibronectin.

Clotrimazole inhibits cell proliferation in vitro and in vivo

Cell proliferation is critically dependent on the regulated movement of ions across various cellular compartments. The antimycotic drug clotrimazole (CLT) has been shown to inhibit movement of Ca2+ and K+ across the plasma membrane. Our results show that CLT inhibits the rate of cell proliferation of normal and cancer cell lines in a reversible and dose-dependent manner in vitro. Moreover, CLT depletes the intracellular Ca2+ stores and prevents the rise in cytosolic Ca2+ that normally follows mitogenic stimulation. In mice with severe combined immunodeficiency disease (SCID) and inoculated intravenously with MM-RU human melanoma cells, daily subcutaneous injections of CLT induced a significant reduction in the number of lung metastases. Modulation of early ionic mitogenic signals and potent inhibition of cell proliferation both in vitro and in vivo are new and potentially useful clinical effects of CLT.

Differential effect of magnesium and calcium on integrin-mediated melanoma cell migration on type IV collagen and fibronectin

We characterized the effects of extracellular Mg2+ and Ca2+ on the regulation of integrin-mediated cell migration of melanoma cells on type IV collagen and fibronectin. Melanoma cell motility was studied using transmembrane migration in modified Boyden chambers and time-lapse video image analysis. Increasing Mg2+ or Ca2+ ion concentration from 0.1 to 10 mM produces distinct effects on melanoma cell migration on type IV collagen. Increasing Mg2+ ion concentration increased cell migration to a maximum at 5 mM, followed by a decrease at 10 mM. In contrast, Ca2+ alone did not support cell migration on this substrate. Combinations of both cations indicate that Ca2+ decreases cell migration in the presence of Mg2+. However, as opposed to the findings on collagen, peak migration on fibronectin was observed at 1 mM and Ca2+ alone was able to support migration on fibronectin. The Mg(2+)-enhanced migration was inhibited by function-blocking monoclonal antibodies anti-alpha 2 or anti-beta 1 integrin subunit on the type IV collagen and anti-alpha 5 and anti-beta 1 on fibronectin. Taken together, the data indicate that Mg2+ promotes the integrin-mediated cell migration, whereas Ca2+ has the opposite effect. The Ca2+ and Mg2+ concentration in the tumour extracellular microenvironment may modulate integrin-mediated functions and melanoma metastasis.

Role of beta 1 integrins in cell spreading and migration of human nevomelanocytes and dysplastic nevi cells on collagen type IV and laminin

We characterized beta 1 integrin subunit expression on three different cultures of benign human nevomelanocytes (NMC) and on four different cell cultures of human dysplastic nevus (DN) cells by flow cytometry analysis and examined their role in mediating cell spreading and migration on collagen type IV (CN IV) and laminin (LN) coated substrates by using a quantitative video image analysis system. The seven human NMC and DNC cultures expressed heterogeneous levels of beta 1, alpha 2, alpha 3 and alpha 6 integrin subunits. Image analysis showed that a significant increase (P < 0.001) in cell spreading and migration of the DN cells was induced on increasing coating concentrations of CN IV and LN. However, the NMC did not show an increase in cell spreading or migration on these substrates when compared to the substrates coated with denatured BSA only. The CN IV-induced cell spreading of the DN cells was significantly inhibited by anti-beta 1 mAb (AIIB2), anti-alpha 2 mAb (P1E6), or anti-alpha 3 mAb (P1B5), but not by mAb against alpha 6 integrin subunit (GoH3). The DN cell spreading on LN was not significantly inhibited by these mAbs. In contrast, the migration of the DN on CN IV and LN was significantly inhibited by anti-beta 1 mAb, anti-alpha 2 mAb, anti-alpha 3 mAb and anti-alpha 6 mAb. These data suggest that the alpha 2 and alpha 3 subunit are important for cell spreading of the DN on CN IV, although they are less important in cell spreading on the extracellular matrix component LN.(ABSTRACT TRUNCATED AT 250 WORDS)

Actin-binding protein expression in benign and malignant melanocytic proliferations

Studies on melanoma cell lines indicate the expression of actin-binding protein (ABP), a peripheral cytoplasmic protein that crosslinks actin, is important for melanoma cell motility. We used an ABP-specific monoclonal antibody to characterize ABP expression in 18 benign nevi and 28 primary and metastatic malignant melanomas. Heterogeneous expression of ABP staining was observed in metastatic melanoma. No clear differences in ABP staining were identified among compound nevi, dysplastic nevi, and superficial spreading melanoma; however, the lentiginous intraepidermal component of the benign and malignant lesions and the pagetoid cells of superficial spreading malignant melanoma were negative for ABP. In contrast, the nested intraepidermal and dermal components of both benign nevi and primary malignant melanoma were positive. The differential expression of ABP of the lentiginous component as opposed to the intraepidermal nests and pagetoid cells of benign nevi or melanoma may represent a capacity of the nested melanocytes to migrate from the epidermis to the dermis during maturation or invasion. Taken together, the findings support that ABP may be important for cell-cell adhesion during tumorigenesis and may play a role in tumor cell ameboid motility during tissue invasion.

Phorbol ester induced rapid attachment and spreading of melanoma cells and the role of extracellular matrix proteins

Phorbol 12-myristate 13-acetate (PMA) is a tumour promotor that acts as a potent protein kinase C (PKC) activator that has significant effects on tumour cell attachment and spreading. We tested whether these effects of PMA may be observed in human melanoma cells, and whether a specific response to extracellular matrix proteins may be mediated by shifts in the expression of beta 1 integrins. We used cell attachment assays, video time lapse cell spreading assays, flow cytometry, function blocking monoclonal antibodies (MAbs) and PKC inhibitor Calphostin C to address these questions. We established that PMA induces a rapid and temporary enhancement of cell attachment and spreading which was not accompanied by a significant change in the expression of beta 1 integrins. Spreading of melanoma cells that were not stimulated with PMA could be significantly blocked with a function blocking MAb (clone P4C10) against the common beta 1 integrin subunit. The spreading and attachment of the PMA treated cells was also significantly reduced, but less so, after MAb treatment. The PMA enhanced cell attachment and spreading could be effectively blocked by RGD sequences and PKC inhibitor. Taken together, our data indicate that PMA induces a rapid and temporary ECM-dependent enhancement of melanoma cell attachment and spreading, and that the response to ECM components appears not to be due to significant shifts in beta 1 integrin expression, but rather to activation of beta 1 integrins.

Differential effects of interleukin 1-alpha (IL-1 alpha) or tumor necrosis factor-alpha (TNF-alpha) on motility of human melanoma cell lines on fibronectin

Interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF-alpha) induce a motogenic response in a number of benign and malignant cells. We examined the chemokinetic effects of these cytokines on the cell migration of four melanoma cell lines on fibronectin using modified Boyden chambers and video-time lapse analysis. Flow cytometry analysis of IL-1 receptors, TNF receptors, and shifts in beta 1 integrin expression were correlated with the effects of these cytokines on cell migration on fibronectin. The four melanoma cell lines exhibited heterogeneous expression of types I and II IL-1 receptors as well as p60 TNF receptors. Scant p80 TNF receptor expression was detected on only one cell line. Three of four melanoma cell lines demonstrated type I IL-1 receptors by Western blotting. IL-1 alpha and TNF-alpha induced heterogeneous modulation of beta 1 integrin expression in the four melanoma cell lines tested; downward shift of the alpha 2, alpha 3, alpha 4, and beta 1 integrin subunits was detected among three of the melanoma cell lines as were upward shifts of the alpha 4, alpha 5, and alpha 6 integrin subunits among three of the melanoma cell lines. IL-1 alpha and TNF-alpha induced enhanced migration on fibronectin in one of the melanoma cell lines and were related to an upward shift in the alpha 4 and alpha 5 integrin subunit expression. Taken together, the findings indicate that expression of a particular receptor for IL-1 or TNF does not necessarily signal a motogenic response in melanoma cells, but induces heterogeneous shifts in beta 1 integrin expression. However, upregulation in alpha 4 and alpha 5 integrin subunits appears to relate to enhanced migration on fibronectin.

Clinical findings, cutaneous pathology, and response to therapy in 21 patients with keratosis pilaris atrophicans

BACKGROUND

Keratosis pilaris atrophicans defines a group of cutaneous disorders characterized by follicular hyperkeratosis and scarring. X-linked dominant inheritance has recently been reported in a Dutch family with a form of keratosis pilaris atrophicans defined as keratosis follicularis spinulosa decalvans, with males more severely affected and having corneal involvement. The clinical manifestations observed in different families by others and ourselves did not follow that pattern, suggesting genetic heterogeneity. We report our experience with 21 unrelated individuals.

RESULTS

There were 15 male and six female patients whose onset of the skin disease was in early childhood but with scalp involvement occurring in the teen years. The cutaneous lesions consisted of follicular papules with scalp involvement present in eight individuals. Half the women had scalp involvement, and one female and one male had eye changes. Familial involvement was observed in three patients and was compatible with dominant inheritance. Histopathologic examination revealed hyperkeratosis of the upper follicle with an inflammatory response that resulted in follicular destruction. Response to therapy including keratolytics, antibiotics, corticosteroids and retinoids was limited.

CONCLUSIONS

Our findings support the hypothesis that there is genetic and clinical heterogeneity among the disorders represented by the term keratosis pilaris atrophicans. The cause of these diseases may be a disorder of the keratinocyte, which is responsible for inducing both the hyperkeratosis and inflammatory changes.

Role of alpha 3 beta 1 and alpha 2 beta 1 integrins in melanoma cell migration

Recent findings indicate that variable expression of beta 1 integrins may play a role in differential melanoma cell motility. Primary melanoma (PM) and metastatic melanoma (MM) cultures, derived from the same patient, were tested for their beta 1, alpha 2, alpha 3 and alpha 6 integrin subunit expression and cell migration on type IV collagen (CN IV) or laminin (LN). The MM cell line expressed markedly increased levels of the beta 1, alpha 2 and alpha 3, but not alpha 6 subunit compared to the PM cell line. The MM cell migration rate was significantly higher than that of the PM cell line on LN- or CN IV-coated substrates. Furthermore, the cell migration rate of both lines was significantly higher (p < 0.001) on these substrates than on the control substrates. The MM and PM cell migration was significantly inhibited by function-blocking anti-beta 1 and anti-alpha 3 MAbs, but not by the anti-alpha 6 MAb tested. In contrast, the anti-alpha 2 MAb significantly inhibited MM but not PM cell migration. These data show that the alpha 3 subunit plays a significant role in melanoma cell motility on CN IV and LN and that the alpha 2 subunit has a significant contribution to the motility of the MM cell line.

Metastatic behavior and tumorigenicity of a human melanoma cell line (MM-RU) after injection into nude mice

The ability of the human amelanotic melanoma cell line MM-RU to produce experimental metastases and to grow tumors at subcutaneous inoculation sites in 4-week-old nude mice was examined. After i.v. inoculation of 10(6) cells, all injected mice (n = 21) developed consistent numbers of metastatic pulmonary colonies within 32 days. The coefficients of variation for the number of colonies were between 17%-23% in three independent experiments. Survival time after i.v. inoculation was 63 +/- 7 days (mean +/- SD) (n = 20). Within 20 days, subcutaneous inoculation of 5 x 10(6) cells resulted in tumor growths of 13 +/- 3 mm (mean +/- SD) at the inoculation sites in all nude mice (n = 12). The MM-RU cell line seems to be a simple, fast vehicle for testing the effect of melanoma growth modulators on experimental pulmonary metastases as well as on subcutaneously growing melanoma.

Organ-specific metastases in immunodeficient mice injected with human melanoma cells: a quantitative pathological analysis

Pathological and morphometric techniques were used to investigate the potential of two human melanoma cell lines for organ colonization in three different immunodeficient mouse strains; nude (nu/nu), NIH triple immunodeficient (TID: nu/nu, bg/bg, xid/xid) and severe combined immunodeficient (SCID) mice. The MM-RU cell line gave rise exclusively to lung metastases, whereas the MM-AN cell line gave rise to lung and extrapulmonary metastases. Although the TID mice showed more pancreatic and brown fat lesions than nude or SCID mice, the overall pattern of distribution of organ metastases among the strains was similar, suggesting that cellular properties intrinsic to the melanoma cells are important for the colonization of specific organs. The metastatic nodules were well circumscribed in all organs and exhibited peripherally located macrophages, except for brain metastases, where a more invasive pattern along vasculature was observed. The differences in cellular infiltrate and infiltrative patterns of the tumors implicate features of the host microenvironment (organ-specific factors) which are, at least in part, independent of the host's genetic background or degree of immunodeficiency. Our findings suggest that intrinsic malignant cellular properties play an important role in organ-specific colonization by haematogenously metastasizing cells.

Role of integrin alpha 2 beta 1 (VLA-2) in the migration of human melanoma cells on laminin and type IV collagen

The random cell migration of four human melanoma cell lines on laminin and type IV collagen-coated substrates was studied by video time-lapse image analysis and compared to the expression of a number of beta 1 integrins including alpha 1 beta 1, alpha 2 beta 1, alpha 3 beta 1, and alpha 6 beta 1 using flow cytometry. These integrins were heterogeneously expressed in the four cell lines tested with three of four lines expressing alpha 2 beta 1. The melanoma cell line that did not express alpha 2 beta 1 exhibited weak attachment and low cell migration rate on both laminin and type IV collagen, whereas the other melanoma cell lines showed an increase in attachment and mean cell migration rate in a dose-dependent manner on the matrix molecules (p < 0.001). The enhanced migration seen in the three cell lines could be specifically inhibited by function blocking anti-beta 1 and anti-alpha 2 monoclonal antibodies (p < 0.001) but not by function blocking anti-alpha 3 and anti-alpha 6 monoclonal antibodies. Image analysis of the cells before and after treatment with anti-beta 1 and anti-alpha 2 MoAb indicated that the inhibition of migration did not result in detectable cell detachment, retraction of cell processes, or other significant cell-shape change. Taken together, the findings suggest that the observable enhanced migration on laminin and type IV collagen of a number of human melanoma cell lines is largely mediated by integrin alpha 2 beta 1.

Histopathologic recognition and grading of dysplastic melanocytic nevi: an interobserver agreement study

Before the controversies surrounding dysplastic melanocytic nevi are resolved, dermatopathologists must be able to reliably distinguish dysplastic nevi from common acquired nevi and malignant melanoma. To establish whether grading of melanocytic dysplasia has any biologic relevance, dermatopathologists must be able to consistently recognize two or more grades of atypia. We studied the concordance among five dermatopathologists for recognition and grading of 60 nevomelanocytic lesions. Ten cases from each of the following categories of melanocytic proliferation were retrieved from the Massachusetts General Hospital files: 1) common melanocytic nevi, 2) melanocytic nevi with features of dysplastic nevi, 3) dysplastic nevi with slight cytologic atypia, 4) dysplastic nevi with moderate cytologic atypia, 5) dysplastic nevi with severe cytologic atypia, and 6) primary malignant melanoma. The slides were reviewed independently; no discussion of diagnostic criteria preceded the review. Overall concordance for diagnosing dysplastic nevi was 77%, with a kappa statistic of 0.55-0.84. Furthermore, in grading dysplastic nevi, experienced dermatopathologists had a concordance ranging from 35% to 58% (kappa value 0.38-0.47). Those with less experience in grading dysplastic nevi had a concordance of 16-65% (kappa value 0.05-0.24). The five observers in this study reliably distinguished dysplastic nevi from common acquired nevi and malignant melanoma. Further refinement of the criteria for grading of nevo-melanocytic dysplasia and experience in grading are critical for accuracy in subcategorization of dysplastic nevi. Consistent, reproducible subcategorization of dysplastic nevi is a requisite before the issue of biologic or prognostic relevance of grading (dysplastic nevi) can be addressed. This study supports the validity of existing criteria for the diagnosis of dysplastic nevi because the problems in diagnosis were at the limits of the spectrum, namely, discrimination of slightly atypical dysplastic nevi from common nevi and severely atypical dysplastic nevi from radial growth phase melanoma.