Effective treatment by glycolic acid peeling for cutaneous manifestation of familial generalized acanthosis nigricans caused by FGFR3 mutation.

BACKGROUND: Acanthosis nigricans (AN) can occur as a cutaneous manifestation of genetic diseases, one of which is associated with activating mutations of the fibroblast growth factor receptor 3 gene (FGFR3). OBJECTIVE: We explored familial AN patients with FGFR3 mutations and examined the effectiveness of glycolic acid (GA) peeling in improving their skin manifestations. METHODS: Sanger sequencing was performed for the genomic DNA extracted from leucocytes of the family members involving familial AN. GA peeling was carried out for the two patients of familial AN once every 2 weeks. RESULTS: Heterozygous c.1949A>C (p.K650T) mutation in FGFR3 was identified for the affected family members examined, whereas the wild-type sequence was found for two unaffected individuals. Hyperpigmentation and coarseness of the skin were improved by GA peeling at regular intervals with few adverse effects. CONCLUSION: We diagnosed our cases as familial generalized AN caused by heterozygous c.1949A>C (p.K650T) mutation of FGFR3. We propose that GA peeling is a useful and safe therapeutic option to treat familial AN.

Effect of alendronate on bone metabolic indices and bone mineral density in patients treated with high-dose glucocorticoid: a prospective study.

SUMMARY: This prospective study, in the very early phase after initiation of glucocorticoid (GC) treatment, showed that alendronate was effective in suppressing accelerated bone resorption and subsequent decrease in bone mineral density (BMD) at the lumbar spine of patients with high-dose GC treatment. INTRODUCTION: How bisphosphonates affect bone metabolism and BMD of patients with high-dose GC in the early phase, especially within 1 month is unclear. METHODS: We examined the prospective effects of daily 5 mg alendronate on bone metabolism and BMD in 20 patients with high-dose GC (at least 40 mg prednisolone/day) and compared them to 34 high-dose GC-treated patients without alendronate. RESULTS: Serum levels of calcium decreased at day 28 in the alendronate group. Urinary calcium excretion significantly increased after day 7 in both groups. The increase in serum parathyroid hormone (PTH) level at day 7 in the control group was not observed in the alendronate group, but PTH levels increased at day 28 and month 3 in the alendronate group. As for the bone turnover markers, the serum osteocalcin level decreased in both alendronate and control groups, but serum bone-type alkaline phosphatase levels did not show significant changes. Although the urinary type I collagen cross-linked N-telopeptide (NTX) level showed significant increases on days 7 and 28 in the control group; such early increases in urinary NTX were not observed in the alendronate group. Thereafter, the urinary NTX levels fell slowly in the alendronate group significantly. BMD at the lumbar spine significantly decreased from month 1 in the control group, whereas in the alendronate group, BMD at the lumbar spine maintained almost the same level at all time points observed. CONCLUSION: Alendronate was effective in suppressing bone resorption and subsequent BMD decrease at the lumbar spine in patients with high-dose GC treatment.

Metabotropic glutamate receptor subtype-1 is essential for in vivo growth of melanoma.

Ectopic expression of metabotropic glutamate receptor subtype 1 (mGluR1) in mouse melanocytes induces melanoma formation. Although requirement of mGluR1 for development of melanoma in the initial stage has been demonstrated, its role in melanoma growth in vivo remains unclear. In this study, we developed novel transgenic mice that conditionally express mGluR1 in melanocytes, using a tetracycline regulatory system. Pigmented lesions on the ears and tails of the transgenic mice began to appear 29 weeks after activation of the mGluR1 transgene, and the transgenic mice produced melanomas at a frequency of 100% 52 weeks after transgene activation. Subsequent inactivation of the mGluR1 transgene in melanoma-bearing mice inhibited melanoma growth with reduction of immunoreactivity to phosphorylated ERK1/2, whereas mice with persistent expression of mGluR1 developed larger melanoma burdens. mGluR1 expression is thus required not only for melanoma development but also for melanoma growth in vivo. These findings suggest that growth of melanoma can be inhibited in vivo by eliminating only one of the multiple genetic anomalies involved in tumorigenesis.

A Zn(II)-glycine complex suppresses UVB-induced melanin production by stimulating metallothionein expression.

Oxidative stress caused by ultraviolet (UV) radiation generates reactive oxygen species (ROS) in the skin, induces the secretion of melanocyte growth and activating factors from keratinocytes, which results in the formation of cutaneous hyper-pigmentation. Thus, increasing the anti-oxidative ability of skin cells is expected to be a good strategy for skin-lightening cosmetics. Metallothionein (MT) is one of the stress-induced proteins and is known to exhibit a strong anti-oxidative property. We previously reported that a zinc(II) complex with glycine (Zn(II)(Gly)(2)) effectively induces MT expression in cultured human keratinocytes. To determine its potential as a new skin lightening active, we examined whether Zn(II)(Gly)(2) regulates the release of melanocyte-activating factors from UVB-irradiated keratinocytes and affects melanin production in a reconstructed human epidermal equivalent. Conditioned medium from UVB-irradiated keratinocytes accelerated melanocyte proliferation to 110%, and that increase could be prevented by pre-treatment with Zn(II)(Gly)(2). In addition, Zn(II)(Gly)(2) significantly reduced both the production of prostaglandin E(2) and proopiomelanocortin expression in UVB-irradiated keratinocytes. Zn(II)(Gly)(2) also decreased melanin production in a reconstructed human epidermal equivalent. These results indicate that MT-induction in the epidermis effectively up-regulates tolerance against oxidative stress and inhibits the secretion of melanocyte growth and activating factors from keratinocytes. Thus, Zn(II)(Gly)(2) is a good candidate as a new skin-lightening active.

N-retinoyl-D-glucosamine, a new retinoic acid agonist, mediates topical retinoid efficacy with no irritation on photoaged skin.

BACKGROUND: Chronic ultraviolet (UV) radiation from sunlight induces wrinkle formation. Retinoic acid (RA) can markedly improve wrinkles, although RA does have some side-effects, such as skin irritation. As the efficacy and cytotoxicity of RA has been traced to its free carboxylic acid, we synthesized a new molecule, N-retinoyl-D-glucosamine (GRA), in which a glucosamine has been attached to the polar end group of all-trans retinoic acid. OBJECTIVES: To analyse the effect of topical GRA in wrinkle repair and anti-irritation in photoaged mice compared with topical RA, as well as to determine retinoic acid receptor (RAR) and retinoid X receptor (RXR) transactivation activity in vitro. METHODS: Hairless mice were irradiated with 60 mJ cm-2 of UVB for 10 weeks, and then topically treated with 0.05% GRA or 0.05% RA for 8 weeks. An in vitro transcriptional assay was performed and the activity of GRA in 293 cells transfected with RAR-alpha or RXR-alpha expression plasmid and luciferase reporter plasmid then determined. RESULTS: Topical GRA and RA brought about almost complete disappearance of the wrinkles caused by UVB irradiation. The two ligands promoted both a wide repair zone histologically, and the expression of type 1 collagen in the skin. In contrast, topical GRA treatment did not produce irritation such as erythema or roughness, or alteration of transepidermal water loss values, compared with RA. In the in vitro luciferase assay, GRA resulted in significant dose-dependent RAR transactivation activity in a 100 times higher concentration range than RA. GRA did not mediate RXR transactivation activity at all. CONCLUSIONS: Topical GRA appears to be able to repair photoaged skin damage without any of the irritation caused by topical RA, probably via RAR transactivation activity.

Effects of glycolic acid on desquamation-regulating proteinases in human stratum corneum.

In order to investigate the mechanism of glycolic acid (GA) function in human stratum corneum, we monitored changes in cathepsin D-like (CD) and chymotrypsin-like (SCCE) proteinases for 3 weeks following topical GA application (50% w/v, pH 0.9) for 30 min to human skin. In the early phase, weakened stratum corneum cohesion in the lower layers was observed on day 2 and the amount of active CD in the upper layer of the stratum corneum was significantly decreased from 30 min until day 2, whereas that in the lower layer remained normal. In contrast, the amount of active SCCE showed no change during the experimental period. The surface pH of the stratum corneum drastically decreased to pH 2 at 30 min and slightly recovered to around pH 3 until 1 day after treatment. From 9 to 19 days, a decrease in corneocyte cell area and a remarkable long-term increase in the amount of active CD in the upper layer were observed. In an in vitro study, the activities of desquamation-regulating proteinases were shown to have remarkably increased at around pH 3, due to activation of CD at its optimal pH. These results suggest that GA functions via at least two different mechanisms, acute activation of CD in the lower layer by acidification around pH 3, along with inactivation of CD in the upper layer, and long-term enhancement of de novo CD production in the few weeks following GA treatment.

Widespread expression of parathyroid hormone-related peptide in melanocytic cells.

BACKGROUND: Parathyroid hormone-related peptide (PTH-rP) was associated with the syndrome of hypercalcaemia of malignancy. An increased serum level of PTH-rP could occur in patients with advanced melanoma. OBJECTIVES: We examined PTH-rP expression in cultured melanocytic cell lines and in lesions of melanocytic origin for associations with clinicopathological variables of disease progression. We measured the supernatant and cell lysate level of PTH-rP in cultured melanoma cells to clarify whether melanoma cells secrete PTH-rP. METHODS: PTH-rP expression was examined by reverse transcriptase-polymerase chain reaction (RT-PCR) in cultured melanocytic cell lines and by immunoperoxidase staining in 18 melanocytic naevi, 40 primary melanoma and 19 metastatic melanoma lesions. The supernatant level of PTH-rP was measured with an immunoradiometric assay. RESULTS: RT-PCR products of PTH-rP mRNA were detected in six of eight melanoma cell lines; however, neither naevus cells nor melanocytes showed positive products. On the other hand, immunohistochemical analysis showed that PTH-rP was widely expressed both in benign and malignant melanocytic lesions. In addition, PTH-rP expression was not associated with any clinicopathological variables. Cell lysate but not the supernatant of melanoma cells showed high PTH-rP levels. CONCLUSIONS: These results suggest that PTH-rP was widely expressed in melanocytic cells; however, the cells did not secrete PTH-rP.

Fusion hybrids with macrophage and melanoma cells up-regulate N-acetylglucosaminyltransferase V, beta1-6 branching, and metastasis.

It was shown previously that a majority of hybrids produced by in vitro fusion of normal macrophages with Cloudman S91 melanoma cells displayed enhanced metastatic potential in vivo, increased motility in vitro, increased ability to produce melanin, and responsiveness to melanocyte stimulating hormone compared with the parental Cloudman S91 melanoma cells. These hybrids also showed altered N-glycosylation consistent with a slower migration pattern of lysosome-associated membrane protein (LAMP-1) on electrophoretic gels. Because LAMP-1 is the major carrier of polylactosamine sugar structures, and synthesis of this complex sugar moiety indicates the extent of beta1,6 branch formation by beta1,6-N-acetyl-glucosaminyltransferase V (GnT-V), we analyzed the expression of GnT-V and beta1,6 branching in highly metastatic macrophage-fusion hybrids and compared with poorly metastatic ones. GnT-V was up-regulated in regard to both mRNA levels and enzymatic activity specifically in metastatic hybrids as well as parental macrophages compared with weakly metastatic hybrids and parental melanoma cells. Macrophages and metastatic hybrids also showed increased binding of the lectin L-phytohemagglutinin, which specifically binds to the beta1,6-branched sugar moiety. In addition, in metastatic hybrids there was increased cell surface expression of LAMP-1 and beta1 integrin, two prominent substrates for GnT-V also known to be associated with metastasis. Finally, exposure of metastatic hybrids in vitro to L-phytohemagglutinin or LAMP-1 completely eliminated melanocyte stimulating hormone/ isobutylmethyl xanthine-induced motility, suggesting a role for GnT-V in the motility of these cells. In summary, macrophage fusion with melanoma cells often increased metastatic potential, which was associated with enhanced expression of GnT-V and beta1,6-branching in glycoproteins. It is suggested that the known correlation with elevated GnT-V in both human and animal metastasis could, at least in some cases, reflect previous fusion of tumor cells with tumor-infiltrating macrophages, which, similar to malignant cells, show elevated expression of GnT-V and beta1,6-branched polylactosamines.

Epidermal changes caused by chronic low-dose UV irradiation induce wrinkle formation in hairless mouse.

To investigate the effects of chronic low-dose UV irradiation on the skin, hairless mice were irradiated with a 1/3 minimal erythemal dose (MED) of UV. We examined the relationship between visible changes and skin damage in the dermis and epidermis. Hairless mice were irradiated with UVB (20 mJ/cm2) and UVA (14 J/cm2) three times a week for 10 weeks, followed by a 24-week non-irradiation period. Visible fine wrinkling was present after 4 weeks of irradiation, and the wrinkling progressively worsened throughout the period of irradiation. The wrinkles remained after irradiation was discontinued. In dermal components, no significant histological changes in the collagen fibers and elastic fibers were found, and the amount of hydroxyproline was also not changed. Thus, in the epidermis, there was a significant increase in the number of stratum corneum layers and the terminal-differentiation marker, filaggrin, positive cells. The intensity of staining for the differentiation marker, keratin 1, was reduced. These changes were accompanied by wrinkle formation, and remained after discontinuance of irradiation. These findings suggested that chronic low-dose UV irradiation induces structural and quantitative changes in the epidermis as a result of keratinization impairment, and that this damage in the epidermis is an important causative factor in wrinkle formation.

The efficacy of glycolic acid for treating wrinkles: analysis using newly developed facial imaging systems equipped with fluorescent illumination.

The clinical characteristics of photodamaged skin, such as coarse and fine wrinkling, can not be quantitatively evaluated from ordinary photographic records. The purpose of this study was to assess the efficacy of glycolic acid (GA) peeling on facial wrinkling, using computer assisted image analysis. This was accomplished with reproducible imaging techniques, which allowed precise repositioning of the subject's face in front of the camera. Two parameters, the change in wrinkle number and the change in wrinkle length were assessed. Although the clinical improvement of wrinkles correlated with both parameters, wrinkle length more precisely reflected the degree of clinical wrinkles, because the wrinkle number appeared to increase as some shallow wrinkles divided into multiple smaller wrinkles during their improvement. Comparison of responses by different age groups showed that the reduction of total wrinkle length was observed in the order of: 50s>30s and 40s>60s>over 70>under 30. The lack of response by subjects over 70 might be due to the nature of their wrinkles being mainly coarse wrinkles rather than fine ones. We next compared the effect of GA by concentration (35, 50 or 70%), but found no significant differences. As the concentration of GA used for treatment was determined by each subject's erythema reaction, our present result suggests that erythema elicited by GA correlates with improvement of wrinkles and that these two phenomena can be induced by a common pathway of GA treatment. This quantitative analysis clearly shows the efficacy and limitation of GA treatment of wrinkles, and might help to disclose the precise mechanisms of GA effects on the skin structure and function.

Tissue factor expression and serum level in patients with melanoma does not correlate with disease progression.

Not only does tissue factor (TF) play a crucial role in hemostasis and thrombosis, but it is also involved in tumor progression and metastatic potency in some malignant tumors. We evaluated the clinical relevance of TF expression in melanocytic tumors and TF serum level in patients with malignant melanoma. TF expression in benign and malignant melanocytic lesions was examined by immunoperoxidase staining in 20 nevi, 41 primary, and 24 metastatic melanoma lesions. TF was detected in 94, 95, and 100% of these lesions, respectively. The staining pattern was membranous and cytoplasmic both in nevi and melanoma cells. This finding was confirmed by western blot analysis using cultured human melanocytes, nevi cells, and melanoma cell lines. TF was also expressed on blood vessels in benign and malignant melanocytic lesions. Expression of TF in primary melanoma lesions was not associated with any clinicopathological variables. In addition, the serum level of TF was elevated in 14% of patients with melanoma; however, it was not correlated with disease progression. These results suggest that TF was ubiquitously expressed in melanocytic cells and its expression was not correlated with disease progression and/or metastatic potency of melanoma cells.

The effect of thioredoxin on the expression of proopiomelanocortin-derived peptides, the melanocortin 1 receptor and cell survival of normal human keratinocytes.

An important constituent of the cellular antioxidant buffering system that controls the redox state of proteins is thioredoxin (TRX), a 13 kDa protein that catalyzes thiol-disulfide exchange reactions, regulates activation of transcription factors, and possesses several other biologic functions similar to cytokines. We have previously reported that TRX released from UVB-irradiated keratinocytes stimulates melanogenesis by upregulating MSH receptor expression and its binding activity in melanocytes. The purpose of this study was to examine the effects of TRX on keratinocytes as an autocrine factor. TRX suppressed the UVB-induced production and secretion of alpha-melanocyte stimulating hormone (alpha-MSH) and of adrenocorticotropic hormone (ACTH), and also suppressed proopiomelanocortin (POMC) mRNA expression by normal human keratinocytes; however, TRX upregulated melanocortin 1 receptor (MC1-R) expression synergistically with UVB in normal human keratinocytes. These results suggest that exogenous TRX regulates expression of those genes in different manners. Furthermore, addition of an antibody against TRX induced cell death in keratinocytes, probably due to enhanced signaling of MSH, as it has been shown that MSH suppresses heat shock protein (hsp) 70 expression in differentiated keratinocytes, which express high levels of MC1-R and decreases their survival rate during oxidative stress. Taken together, the results suggest that keratinocyte-derived TRX regulates the expression of stress inducible neuropeptides and their receptor, and is critically involved in the survival of keratinocytes.

Small Gtpase rab3A is associated with melanosomes in melanoma cells.

Rab3A is a small guanosine triphosphate (GTP)-binding protein that has been recently implicated in intracellular vesicle transport and the secretion of neurotransmitters in neuronal cells. We demonstrate here that Rab3A is associated with melanosomes in pigment cells. Rab3A as well as Rabphilin3A, a putative target protein of Rab3A, were detected in the melanosome fraction, purified from B16 murine melanoma cells by sucrose density gradient ultracentrifugation. In contrast, Rab GDP dissociation inhibitor (GDI), a GDP/GTP exchange protein for Rab3A, was found in the cytosol fraction. Further studies using confocal laser scanning microscopy and immunoelectron microscopy revealed that immunoreactive Rab3A is localized in conjunction with the melanosomal membrane. These results suggest the possibility of involvement of Rab3A-Rabphilin3A complex, regulated by Rab GDI, in the intracellular transport of melanosomes in pigment cells.

Depigmenting effect of alpha-tocopheryl ferulate on normal human melanocytes.

Oral vitamin E supplementation has been reported to improve facial hyperpigmentation. alpha-Tocopheryl ferulate (alpha-TF) is a compound of alpha-tocopherol (alpha-T) and ferulic acid connected by an ester bond. Ferulic acid is also an antioxidant, and could scavenge free radicals induced by ultraviolet (UV) radiation, and thus maintain the long-lasting antioxidative effect of alpha-T. Previously we have reported that alpha-TF inhibited melanogenesis in human melanoma cells. To know whether alpha-TF might be useful as a whitening agent to improve and prevent facial hyperpigmentation, the depigmenting effect of alpha-TF in normal human melanocytes was examined in this study. The results showed that 30 microg/ml of alpha-TF dissolved in 150 microg/ml of lecithin inhibited melanization significantly without inhibiting cell growth. This phenotypic change was associated with the inhibition of tyrosinase and the degree of inhibition was dose dependent. No significant effect on DOPAchrome tautomerase (DT) activity was observed. These results suggest that alpha-TF is a candidate for an efficient whitening agent which suppresses melanogenesis. In this paper, the role of alpha-T and alpha-TF in inhibiting biological reactions induced by reactive oxygen species (ROS) is also discussed.

A case of classic Kaposi's sarcoma in a Japanese man: detection of human herpes virus 8 (HHV-8) infection by means of polymerase chain reaction and immunofluorescence assay.

The recently discovered human herpes virus 8 (HHV-8) has been implicated in the pathogenesis of Kaposi's sarcoma (KS). Because classic KS in Japan is rare and the detection of HHV-8 DNA by polymerase chain reaction (PCR) has been successful only in limited cases, the frequency and role of HHV-8 infection in KS in Japan remain unclear. Herein we report a case of classic KS in a Japanese man whose HHV-8 infection was confirmed by the detection of lesional viral DNA and serum antibodies against lytic antigen.

Expression of tyrosinase, TRP-1 and TRP-2 in ultraviolet-irradiated human melanomas and melanocytes: TRP-2 protects melanoma cells from ultraviolet B induced apoptosis.

Tyrosinase related protein (TRP)-1 and TRP-2 are known to regulate the quality of melanin, and recently their potential role in inhibiting apoptosis have also been reported. To study the role of tyrosinase, TRP-1 and TRP-2 in the growth, differentiation and cell death of ultraviolet B (UVB) irradiated melanocytes, the expression of these proteins in amelanotic and melanotic cells was examined. Expression of tyrosinase and TRP-1 correlated with melanin content, which was upregulated after repeated irradiation of melanotic cells by low doses of UVB. In contrast, the expression and activity of TRP-2 correlated with cell proliferation, but not with pigmentation. In one melanotic melanoma cell line, significant suppression of cell proliferation was observed after low or high doses of UVB irradiation, possibly due to apoptotic changes. TRP-2 expression was remarkably reduced in UVB-irradiated cells, and transfection with TRP-2 expression vector rescued these cells from UVB-induced apoptosis. These results indicate that TRP-2 expression is closely associated with the regulation of cell growth/survival of melanocytes exposed to UVB and that TRP-2 plays a role in protecting melanoma cells from UVB-induced apoptosis.

Upregulation of mRNA for the melanocortin-1 receptor but not for melanogenic proteins in macrophage x melanoma fusion hybrids exhibiting increased melanogenic and metastatic potential.

Fusion of mouse peritoneal macrophages or human blood monocytes with weakly metastatic mouse Cloudman S91 melanoma cells resulted in hybrids with enhanced metastatic potential (Rachkovsky et al., 1998. Clin. Exp. Metastasis, 16: 299-312). With few exceptions, such hybrids also showed increased basal- and MSH-induced pigmentation, at least in part through increased N-glycosylation of melanogenic proteins (Sodi et al., 1998. Pigment Cell Res., 11: 299-309). Here we report analyses regarding expression of the melanocyte-stimulating hormone (MSH) receptor (melanocortin-1 receptor, MC1-R) and the melanogenic proteins, tyrosinase (E.C. 1.14.18.1), tyrosinase-related protein 1 (TRP-1), and the tyrosinase-related protein 2 (TRP-2, E.C. 5.3.2.3), by a panel of cell lines consisting of parental Cloudman S91 melanoma cells, macrophages from DBA/2J mice, artificially derived macrophage x melanoma hybrids of high and low metastatic potential, and a naturally occurring highly metastatic hybrid between a Cloudman S91 tumor cell and a DBA/2J tumor-infiltrating cell. We show that incubation of cells with MSH/isobutylmethylxanthine (IBMX) resulted in strong melanogenic and morphologic responses in high metastatic hybrids compared to parental cells and the low metastatic hybrid, and that high metastatic hybrids exhibit increased mRNA expression for MC1-R accompanied by increased 125I-alphaMSH binding. Although tyrosinase activity and the protein level for tyrosinase and TRP-2, but not for TRP-1, were increased in the high metastatic hybrids versus the other cells, no significant changes in mRNA either for tyrosinase or for TRPs were observed in them. Furthermore, unlike tyrosinase, the abundance and gel mobility pattern of TRP-2 did not correlate with changes in activity in all hybrids and parental melanoma cells. The results suggest that although the activity MC1-R and tyrosinase correlate with enhanced basal as well as MSH-induced melanogenesis in metastatic/melanotic hybrids, their expression is differentially regulated, i.e., regulation of MC1-R while at transcriptional level, the TRPs are primarily regulated via post-transcriptional mechanisms in high metastatic hybrids.

Expression of proopiomelanocortin, corticotropin-releasing hormone (CRH), and CRH receptor in melanoma cells, nevus cells, and normal human melanocytes.

Proopiomelanocortin (POMC) is a 31 kDa prohormone that is processed to various bioactive peptides, including adrenocorticotropin (ACTH), melanotropins (alpha, beta, gamma-MSH), lipotropins, and endorphins. POMC is expressed not only in the pituitary gland but also in a variety of nonpituitary organs and tumors, including melanomas. We previously showed that normal human melanocytes produce and secrete alpha-MSH and ACTH, and furthermore, that advanced melanoma cells generally produce higher amounts of POMC peptides that correlate with tumor progression. To elucidate the mechanism of this upregulation, the expression of genes encoding corticotropin-releasing hormone (CRH) and its receptor, CRH-R, as well as POMC and the MSH receptor (MC1-R), was evaluated by reverse transcriptase-polymerase chain reaction using cultured human melanoma cells, nevus cells, and normal melanocytes. Our results show that all melanocytic cells express CRH, CRH-R, POMC, and MC1-R, with highest intensities in melanoma cells. Furthermore, immunohistochemistry shows that CRH as well as POMC is strongly expressed in advanced melanomas, such as vertically growing lesions of acral lentiginous, nodular and metastatic melanomas, in contrast to negative expression in nevus cells. These results indicate that tumor progression accentuates CRH, CRH-R, and POMC expression by melanoma cells.

The depigmenting effect of alpha-tocopheryl ferulate on human melanoma cells.

Oral vitamin E (alpha-tocopherol, alpha-T) supplementation has been reported to improve facial hyperpigmentation. alpha-Tocopheryl ferulate (alpha-TF) is a compound of alpha-T and ferulic acid connected by an ester bond; ferulic acid is also an antioxidant, and could scavenge free radicals induced by ultraviolet (UV) radiation, and thus maintain the long-lasting antioxidative effect of alpha-T. Our aim was to see whether alpha-TF might be useful as a whitening agent and an antioxidant to improve and prevent facial hyperpigmentation following UV exposure. In this study, the inhibitory effect of alpha-TF on melanogenesis was examined biochemically using human melanoma cells in culture. The results show that alpha-TF, solubilized in ethanol or in 0.5% lecithin, inhibited melanization significantly, as did alpha-T at a concentration of 100 microg/mL, without inhibiting cell growth. This phenotypic change was associated with inhibition of tyrosinase and 5, 6-dihydroxyindole-2-carboxylic acid polymerase activities, and the degree of inhibition was dose dependent. No significant effect on DOPAchrome tautomerase activity was observed. alpha-TF did not directly inhibit tyrosinase activity of the large granule fraction extracted from human melanoma cells, and Western blotting revealed that there were no changes in protein content or in molecular size of tyrosinase, tyrosinase-related protein (TRP)-1 or TRP-2. Therefore, the inhibition of tyrosinase activity by alpha-TF might be due to effects at the post-translational level, and possibly by a secondary molecule activated by alpha-TF. These results suggest that alpha-TF is a candidate for an efficient whitening agent which suppresses melanogenesis and inhibits biological reactions induced by reactive oxygen species.