The Lives of Pigment Cells

Clinicopathological characteristics of malignant melanomas of the skin and gastrointestinal tract

The present study examined the differences between gastrointestinal melanoma (GM) and skin melanoma (SM). The clinicopathological characteristics, the expression of melanoma stem cell markers nestin, sex determining region Y-box 2 and ATP-binding cassette sub-family B member 5, and the presence of the BRAF^V600E mutation were evaluated in 10 cases of GM and 31 cases of SM. Patients with GM had an increased mean age compared with those with SM (76 vs. 68 years). In addition, GMs were significantly more likely than SMs to be amelanotic (50 vs. 7%; P=0.001) and display round cells (70 vs. 23%; P=0.02). The mitosis rate was also significantly higher in GM compared with SM (P<0.05). The incidence of lymph-node metastasis (60 vs. 32%; P<0.05) and distant metastasis (10 vs. 6.5%, P=0.02) was significantly higher in GMs compared with SMs. The expression of stem cell markers did not differ significantly between groups, however, in the SM group advanced-stage disease was associated with a significantly higher expression of nestin than early-stage disease (P<0.05). Immunohistochemically, the expression of BRAF^V600E was significantly lower in GMs compared with in SMs (1.0 vs. 3.3; P=0.01). These findings indicate that the identification of these features may aid in the diagnosis of GM and SM, as well as contribute to the development of novel targeted therapies against GM.

A primer on pigmentation

There is at least a temporary loss of skin pigmentation with all but first-degree burns. Commonly, pigment changes persist for months, and sometimes, permanent changes in skin color add to the ultimate change in appearance that commonly affects burn patients. There are many different treatment modalities for the treatment of pigment changes, but most of them have little scientific basis and often lead to disappointing results. The purpose of this review is to discuss the molecular and cellular mechanisms of skin pigmentation, mechanisms of repigmentation after burns, treatment options for dealing with pigmentation changes, and advice for dealing with the sun after burn injury.

Comparison of primary and metastatic malignant melanoma of the esophagus: clinicopathologic review of 10 cases

CONTEXT

Primary esophageal melanoma (PEM) is a rare disease and is difficult to distinguish from other esophageal malignancies and from metastatic melanoma.

OBJECTIVE

To develop diagnostic criteria for PEM, we compared the clinicopathologic features of 5 PEMs and 5 metastatic melanomas to esophagus.

DESIGN

Ten cases of esophageal melanoma, including 4 surgically resected specimens, 2 autopsy cases, and 4 cases reported on mucosal biopsies, were reviewed. The histologic parameters used in this study were well-characterized features for cutaneous melanoma, including junctional component (in situ melanoma), radial growth phase, modified Breslow thickness, depth of invasion, lymphovascular invasion, satellitosis, predominant type of cytology, and regional lymph node metastasis. Clinical and follow-up information was obtained by reviewing patients' medical records.

RESULTS

Previous history of cutaneous melanoma was present in all 5 cases of metastatic esophageal melanoma but was not present in the 5 patients with PEMs. In situ melanoma and/or radial growth phase were identified in all 5 PEMs but were not present in any of the metastatic cases. Among the 4 resected and 2 autopsy cases, melanocytosis and mixed epithelioid and spindle cell morphology was present in 2 (50%) of 4 PEMs but was not present in 2 (40%) of the metastatic melanomas. Melanin pigment was detectable in all cases. Patients with PEM had better survival than those who had metastatic melanoma to esophagus (P = .03).

CONCLUSIONS

The presence of in situ melanoma, radial growth phase, melanocytosis, and mixed epithelioid and spindle cell morphology, in the context of no history of melanoma, distinguishes PEM from metastatic melanoma.

The effect of ultraviolet radiation on choroidal melanocytes and melanoma cell lines: cell survival and matrix metalloproteinase production

BACKGROUND

Ultraviolet radiation (UVR) can induce DNA damage and regulate the expression of factors important for tumour growth and metastasis, including matrix metalloproteinases (MMPs). Epidemiological studies suggest that chronic UVR exposure, especially during early adulthood, may be a risk factor in patients with choroidal melanoma. However, the effects of UV(R)-B on human choroidal melanocyte survival and growth are unknown. In this study, we investigated if UV(R)-B affected the in vitro survival, growth and MMP production of choroidal melanocytes and melanoma cells.

METHODS

Cultures of primary choroidal melanocytes and melanoma cell lines (OCM-1 and OCM-8) were exposed to UV(R)-B (0-30 mJ/cm(2)). The cell morphology and growth were examined, and cell viability was assessed using an MTT assay. Gelatin zymography was used to assess the enzymatic activity for MMP-2 and -9 in conditioned media following UV(R)-B treatment.

RESULTS

UV(R)-B > or =20 mJ/cm(2) was cytotoxic for choroidal melanocytes. Cytotoxic doses of 5 to 10 mJ/cm(2) were found for OCM-8 and OCM-1 melanoma cell lines. Low levels of UV(R)-B (2.5 and 3.5 mJ/cm(2)) significantly reduced melanoma cell viability after 48 h, although melanocyte viability was not affected by doses of UV(R)-B <10 mJ/cm(2). Conditioned media from melanoma cells and melanocytes displayed pro-MMP-2 activity independent of UV(R)-B. Control and UV(R)-B-treated OCM-1 cells secreted active MMP-2 up to 72 h. Pro-MMP-9 activity was seen from 36 h for control and UV(R)-B-treated OCM-1 and OCM-8 cells.

CONCLUSIONS

Melanocytes appeared more resistant to physiological doses of UV(R)-B than melanoma cells; the potential of melanocytes to initially survive DNA damage following UV(R)-B exposure may be relevant to the subsequent transformation of melanocytes to melanomas. Although UV(R)-B did not induce the production and/or activation of MMP-2 and -9 in melanocytes or melanoma cells, we are currently investigating whether DNA damage-response genes such as p53 and p21 can be regulated following UVR exposure, and whether they are important for choroidal melanoma development.

Primary malignant melanoma of the oesophagus: a clinical and pathological study with emphasis on the immunophenotype of the tumours for melanocyte differentiation markers and cancer/testis antigens

SUMMARY

Primary malignant melanomas of the oesophageal squamous mucosa are exceedingly rare. We present here the clinical and pathological findings of 10 patients (mean age 64 years) with primary oesophageal melanoma, with emphasis on the immunophenotype of the tumours. The majority of melanomas were located in the mid to distal oesophagus and were large (mean tumour size at the time of diagnosis 6.2 cm; mean depth of invasion 1.86 cm). All but two of the melanomas were associated with an extensive in situ component. Half of the tumours were amelanotic. The histological spectrum was wide, including appearances mimicking lymphoma, poorly differentiated adenocarcinoma or sarcoma. Immunohistochemical studies were performed on six tumours using monoclonal antibodies (MAb) to S100 protein, tyrosinase (MAb T311), Melan-A (MAb A103), and gp100 (MAb HMB-45), as well as antibodies to five cancer/testis (CT) antigens (MAb CT7-33 to CT7/MAGE-C1, MAb ESO121 to NY-ESO-1, MAb 57B to MAGE-A4, MAb MA454 to MAGE-A1, and MAb M3H67 to MAGE-A3). Seven patients had metastatic disease at the time of presentation. All but one patient underwent resection of the tumour with negative surgical margins. Survival was poor, with a mean survival of 19.8 months. One patient, however, whose tumour was limited to the submucosa, is still alive 108 months post-oesophagectomy. All six melanomas examined by immunohistochemistry were positive for all the melanocyte differentiation markers tested. In addition, they were all positive for CT antigens, with MA454 being the most commonly found, suggesting that CT antigens may be a promising immunotherapeutic target for oesophageal melanomas.

Melanin pigmentation in mammalian skin and its hormonal regulation

Cutaneous melanin pigment plays a critical role in camouflage, mimicry, social communication, and protection against harmful effects of solar radiation. Melanogenesis is under complex regulatory control by multiple agents interacting via pathways activated by receptor-dependent and -independent mechanisms, in hormonal, auto-, para-, or intracrine fashion. Because of the multidirectional nature and heterogeneous character of the melanogenesis modifying agents, its controlling factors are not organized into simple linear sequences, but they interphase instead in a multidimensional network, with extensive functional overlapping with connections arranged both in series and in parallel. The most important positive regulator of melanogenesis is the MC1 receptor with its ligands melanocortins and ACTH, whereas among the negative regulators agouti protein stands out, determining intensity of melanogenesis and also the type of melanin synthesized. Within the context of the skin as a stress organ, melanogenic activity serves as a unique molecular sensor and transducer of noxious signals and as regulator of local homeostasis. In keeping with these multiple roles, melanogenesis is controlled by a highly structured system, active since early embryogenesis and capable of superselective functional regulation that may reach down to the cellular level represented by single melanocytes. Indeed, the significance of melanogenesis extends beyond the mere assignment of a color trait.

Fundus pigmentation and the dark-adapted electroretinogram

Dark-adapted electroretinograms were obtained over a 3.6-log range of stimulus intensities from 17 black and 15 white normal subjects. Subjects were grouped on the basis of light or dark fundus pigmentation, determined from digitized fundus photographs. B-wave amplitudes for each group were fitted by the Naka-Rushton equation, and the measures Vmax, log K, and n were determined. The luminance-response functions revealed that subjects with light fundi had larger b-wave amplitudes at all luminance levels. There was a significant difference between groups for Vmax and n but not for log K. A comparison of b-wave implicit times showed no significant difference between subjects with dark and light fundi. Ancillary tests and multiple regression analysis suggested that the relationship between Vmax and fundus pigmentation could not be attributed to age, gender, refractive error, axial length or intraocular pressure. The results have implications for the collection of normative electroretinographic data and for the interpretation of electroretinogram results.