Takashi Horikoshi

Evaluation of melanin-related metabolites as markers of melanoma progression

Background. Urinary excretion of 5‐S‐cysteinyldopa (5‐S‐CD) has been used as a biochemical marker of melanoma progression. Melanomas produce not only 5‐S‐CD but also 5,6‐dihydroxyindole‐2‐carboxylic acid (5,6DHI2C) as major intermediates in melanin formation. 5,6DHI2C is then metabolized to the two O‐methyl derivatives, 5H6MI2C and 6H5MI2C. The aim of this study was to determine which marker in serum and urine most sensitively reflected the progression of melanoma.

Expression of the p53 protein in malignant melanomas as a prognostic indicator.

It is currently widely accepted that the tumour suppressor gene p53 is critically involved in the proliferation and differentiation of tumour cells including melanoma cells. In the present study, we examined 60 cases of primary melanoma to compare the expression of p53 protein with conventional prognostic markers for melanoma such as clinical and histological parameters. No correlation was found between the p53 protein and clinical factors except for the presence of a metastatic node and development to clinical stage II. However, the expression of p53 protein was significantly associated with tumour thickness over 1.5 mm, levels IV and V of invasion, the presence of ulceration, and high mitotic rate for 5-year survival rate. Although many questions still remain to be answered, our results and those of others for various other malignant tumours, implicate p53 in malignant transformation of pigment cells. Indeed, it could be a new marker for an unfavourable prognosis of malignant melanoma, even though the gene mutation in this highly lethal tumour has yet to be established.

Long-Term Continuous versus Intermittent Cyclosporin: Therapy for Psoriasis

A multicenter randomized controlled study was conducted to assess the long‐term efficacy and safety of cyclosporin A therapy for psoriasis using either a continuous or an intermittent regimen. Initially, both regimens consisted of 3–5 mg/kg/day administration of CyA. Once remission was obtained, CyA dose was maintained between 0.5 and 3 mg/kg/day under the continuous regimen, while under the intermittent regimen, CyA dose was tapered off and, when necessary, topical corticosteroids were used until relapse occurred. Thirty‐one patients were followed for at least 48 months (mean follow‐up period: 55.9 ± 4.6 months): 15 received continuous therapy, and 16 received intermittent therapy. With both regimens, the PASI (Psoriasis Area and Severity Index) score was maintained at 5–12 points throughout the follow‐up period. The score was decreased by more than 70% from baseline with both regimens: the responses between them were not significantly different. However, overall control of psoriasis, as assessed from the averaged PASI score, was better in the patients receiving continuous therapy. Although the overall frequency of adverse reactions was similar for the two regimens, cancer occurred in two patients on continuous therapy (gastric cancer and hepatocellular carcinoma in one patient each). We could not, however, definitely attribute the cancers in the two patients to continuous therapy itself. There was a significantly higher incidence of renal impairment in elderly patients receiving either regimen when compared with younger patients. In conclusion, CyA administered to psoriasis patients under both regimens exhibited long‐term efficacy and tolerability. Despite a lower overall efficacy, it seems proper to conclude that intermittent therapy is more useful than continuous therapy due to the occurrence of malignancies with continuous therapy. Further investigation is required to determine whether intermittent therapy is really safer than continuous therapy, and, if so, how it should be designed to minimize long‐term adverse reactions and achieve overall control comparable to that of continuous CyA therapy.

A patient with plaque-stage mycosis fungoides has successfully been treated with long-term administration of IFN-γ and has been in complete remission for more than 6 years

Summary We report the successful treatment of a patient with plaque‐stage mycosis fungoides with long‐term and intravenous administration of recombinant human interferon‐γ (IFN‐γ) and discuss the possible mechanisms of this therapy.

Serum 5‐S‐Cysteinyldopa (5‐S‐CD) as a Marker of Melanoma Progression

We previously reported that serum 5‐S‐cysteinyldopa (5‐S‐CD) tended to elevate earlier and reflect melanoma progression better than urinary 5‐S‐CD. In patients without metastatic melanomas, serum concentration and urinary excretion of 5‐S‐CD and 6‐hydroxy‐5‐methoxyindole‐2‐carboxylic acid (6H5MI2C) were within the upper limits of normal controls. In this report, we presented more precisely the changes in these melanin‐related markers and clinical courses of four melanoma patients. Serum and 24‐hour urine samples were serially collected and assayed every 1 to 4 months. Three of them developed stage IV malignant melanomas and died of metastatic disease. 6H5MI2C in serum and urine did not reflect the progression of disease. Among the 4 parameters considered, 5‐S‐CD in serum appeared to be the best biochemical marker for melanoma progression. Serum 5‐S‐CD over the upper limit of 10 nmol/L was suggested as a serious sign of the progression of melanoma.

Dysplastic melanocytic nevus. Electron-microscopic observation as a diagnostic tool.

Dysplastic melanocytic nevi (DMN) are distinctive cutaneous nevomelanocytic lesions that possess unique clinical and histopathological features. In our previous study, we showed that the fine structure of melanosomes in epidermal melanocytes of DMN are abnormal and reveal deranged melanogenesis. This study is an extension of our previous study and clarifies the fine structure of melanosomes in both epidermal melanocytes and keratino-cytes with observations in an additional 10 cases of DMN with and without a marked mesenchymal response. We found (a) that a poor mesenchymal response does not exclude fine structural abnormality of melanosomes in DMN; (b) that abnormal melanosomes are manifested by a spherical shape with either fine granules or incompletely developed lamellae and/or both; (c) that melanization occurs unevenly on the spherical granular and/or incompletely on the lamellar matrices; and (d) that these abnormal melanosomes are transferred to keratinocytes before being completely melanized, and they reveal marked degradation. We suggest that the fine structural characterization of abnormal melanosomes is a new adjunct for histopathological diagnosis of DMN.

Up‐regulation of ICAM‐1 expression on human dermal fibroblasts by IFN β in the presence of TNF‐α

Unstimulated human fibroblasts show low or undetectable ICAM‐1 expression. Interferon‐beta (IFN‐β) at concentrations of 10,100, and 1000 IU/ml in the presence of tumor necrosis factor‐alpha (TNF‐α) significantly increased the ICAM‐I expression of fibroblasts in a dose‐dependent manner. Treatment with IFN‐β alone, however, did not up‐regulate the ICAM‐1 expression. Furthermore the attachment of peripheral blood mononuclear cells (PBMCs) to cytokine‐treated fibroblasts was increased. This augmented attachment was partly inhibited by anti‐ICAM‐1 antibody. These results suggest that IFN‐β and TNF‐α may cooperatively modulate the attachment of PBMCs in the dermis.

HLA class I antigens in Japanese patients with melanoma.

In this study, we analyzed the frequencies of human leukocyte antigen (HLA) class I alleles in 110 Japanese patients with melanoma using serological methods, and compared such frequencies with clinical parameters. As expected, frequencies of HLA allele distribution in patients with melanoma reflected the frequencies observed in the normal Japanese population. Because these are different from populations belonging to other races (e.g., white), it followed that the HLA allele distribution in melanoma patients varies among different races. This differences may have significant implications for T-cell-mediated, HLA-restricted therapeutic modalities. No significant associations between HLA and clinical parameters were noted in this study. This report may help design future clinical trials involving therapeutic approaches based on HLA-restricted mechanisms.

Alteration of Melanoma Melanogenesis by Phenotypic Modifiers

Human melanoma cells (MM96E) were incubated with a phenotypic modifier (L‐ethionine) to compare its effects on phenotypic expression with those induced by sodium butyrate and dimethyl sulfoxide. In contrast to the latter agents, L‐ethionine (8mM) failed to arrest the cell cycle at the G1 phase or to inhibit colony formation ability after 48 hr incubation. Tyrosinase activity changed in parallel with 5‐S‐cysteinyldopa (5‐S‐CD) content during treatment with sodium butyrate or dimethyl sulfoxide. Tyrosinase was inhibited in L‐ethionine‐treated cells, probably because of metabolism of L‐ethionine to sulfhydryl compounds; this remains to be clarified. Gamma‐glutamyl transpeptidase activity changed inversely with tyrosinase activity after sodium butyrate or dimethyl sulfoxide incubation, whereas L‐ethionine did not significantly alter the enzyme activity. In addition, only sodium butyrate induced alkaline phosphatase activity. L‐ethionine was less effective than sodium butyrate or dimethyl sulfoxide in inhibiting expression of the B8G3 melanosomal antigen, as determined by Western blotting. These results suggest that phenotypic modifiers (differentiation inducers) affect melanoma cells in various ways and that melanogenesis therefore reflects only one aspect of differentiation in pigment cells.