Sub-lethal effects of exposing the human melanoma cell line SKmel-23 to 532 nm laser light

Dose-dependent study of effects of 532-nm continuous wave laser on rat skin: A mechanistic insight

Visible lasers emitting in the green spectral region are being routinely employed in various medical and defense fields namely treatment of pigmented lesions, tattoo inks, port wine stains, dazzling the target or mob dispersal. Despite their increasing applications, lasers also tend to pose occupational hazards to operators, ancillary personnel, individuals undergoing laser therapies. This study was aimed at investigating the effects of different doses of 532-nm continuous wave laser on rat skin. The present study demonstrated that higher fluences of 532-nm continuous wave (CW) laser induces significant tissue damage through induction of tumor necrosis factor-α, cyclooxygenase-2, tumor protein (p53), PARP 1, caspase3 which in turn leads to tissue damage and cell death. Furthermore, level of heat shock proteins, pAkt were found up-regulated as a cope up response to laser-induced stress. On the basis of the findings, irradiation with 532-nm CW laser up to 2.5 J/cm² was found within the safe exposure limits. Thus, it is probably the first attempt to demonstrate the tissue damage induced by 532-nm CW laser on skin, which may help in choosing safe laser dose for certain skin-based applications and evolving methods to ameliorate laser-inflicted injuries.

Burn unit experience treating giant melanocytic nevi: 10-year review

Giant congenital melanocytic nevi (GCMN) are rare lesions that are present in 1 in every 20,000 new births. A 10-year review of all patients treated at a pediatric burn center was performed with the goal of identifying the characteristics of patients with GCMN and the outcomes of the treatment provided in a burn center. Thirty-six patients met the definition of GCMN; 64% were female and 36% were male. The most common ethnicity was white (47%), followed by Latino (19%). Most patients were between the ages of 1 and 10 years at the time of their first procedure (64%), and the mean age of patients at the time of their first procedure was 7 years. Eighty-nine percent had only one lesion. The most common location of lesions was the face (64%), followed by the scalp (17%) and back (17%). Seventy-four percent of the samples sent to pathology were congenital compound melanocytic nevi, and 20% were congenital intradermal melanocytic nevi. None of the lesions contained malignant changes at the time of the pathological examination. The various treatment modalities provided in the burn unit are reviewed. The authors conclude that the burn unit is an ideal setting for the treatment of GCMN.

Giant congenital melanocytic nevi

BACKGROUND

: Giant congenital melanocytic nevi are rare lesions with the potential to regress into malignant melanoma and/or neurocutaneous melanosis. Appropriate investigations include a screening magnetic resonance imaging scan, neurologic evaluation, and serial clinical observations looking for the development of these complications. Numerous excisional and nonexcisional options have been described for the management of giant congenital melanocytic nevi.

METHODS

: A MEDLINE search was performed to obtain all relevant citations.

CONCLUSIONS

: To successfully treat these complex lesions, the plastic surgeon must understand the disease process, the natural history and complications, and the options for treatment.

The effect of low-level laser irradiation (In-Ga-Al-AsP - 660 nm) on melanoma in vitro and in vivo

BACKGROUND

It has been speculated that the biostimulatory effect of Low Level Laser Therapy could cause undesirable enhancement of tumor growth in neoplastic diseases. The aim of the present study is to analyze the behavior of melanoma cells (B16F10) in vitro and the in vivo development of melanoma in mice after laser irradiation.

METHODS

We performed a controlled in vitro study on B16F10 melanoma cells to investigate cell viability and cell cycle changes by the Tripan Blue, MTT and cell quest histogram tests at 24, 48 and 72 h post irradiation. The in vivo mouse model (male Balb C, n = 21) of melanoma was used to analyze tumor volume and histological characteristics. Laser irradiation was performed three times (once a day for three consecutive days) with a 660 nm 50 mW CW laser, beam spot size 2 mm(2), irradiance 2.5 W/cm(2) and irradiation times of 60s (dose 150 J/cm(2)) and 420s (dose 1050 J/cm(2)) respectively.

RESULTS

There were no statistically significant differences between the in vitro groups, except for an increase in the hypodiploid melanoma cells (8.48 +/- 1.40% and 4.26 +/- 0.60%) at 72 h post-irradiation. This cancer-protective effect was not reproduced in the in vivo experiment where outcome measures for the 150 J/cm(2) dose group were not significantly different from controls. For the 1050 J/cm(2) dose group, there were significant increases in tumor volume, blood vessels and cell abnormalities compared to the other groups.

CONCLUSION

LLLT Irradiation should be avoided over melanomas as the combination of high irradiance (2.5 W/cm(2)) and high dose (1050 J/cm(2)) significantly increases melanoma tumor growth in vivo.

Giant congenital melanocytic nevi

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Define what is meant by a giant congenital melanocytic nevus and understand its histologic properties. 2. Know the natural history and potential complications associated with a giant congenital melanocytic nevus. 3. Outline the nonsurgical and surgical options available to treat a giant congenital melanocytic nevus.

BACKGROUND

Giant congenital melanocytic nevi are rare lesions with a propensity to degenerate to malignant melanoma. Certain lesions also may be associated with neurocutaneous melanosis, which can on occasion be symptomatic. Appropriate investigations include a screening magnetic resonance imaging scan, neurologic evaluation, and serial clinical observations for the development of cutaneous melanoma. A variety of nonsurgical and surgical options are possible for the treatment of giant congenital melanocytic nevi.

METHODS

A MEDLINE search was performed to gather all pertinent articles from 1955 to 2005.

RESULTS

Giant congenital melanocytic nevi are a difficult diagnostic and reconstructive challenge, requiring careful preoperative evaluation, staged surgical excision, and lifelong patient monitoring and follow-up. With proper treatment, patients can expect a decreased risk of melanoma, with the possibility for early detection and cure of melanoma, amelioration of symptoms, improved aesthetics and psychosocial sequelae, and maintenance of function.

CONCLUSION

The plastic surgeon treating these challenging lesions must have a solid working knowledge of the disease's histology, its natural history and complications, and the options for treatment.

Biostimulation of dermal fibroblast by sublethal Q-switched Nd:YAG 532nm laser: Collagen remodeling and pigmentation

The application of medical lasers in treating pigmented lesions has rapidly developed over the past decade. In both clinical and cosmetic application, melanin is targeted in pigmented areas and destroyed by the mechanism of selective photothermolysis. When laser radiation passes through superficial pigmented tissue, energy will be further reduced by dermal collagen scattering and absorption. Non-pigmented dermal fibroblasts will be exposed to co-incidental laser irradiation at lower energy levels. Biostimulation of dermal fibroblasts by low energy laser is reported in this paper. The Q-switched frequency doubled Nd:YAG 532nm laser used in clinical laser therapy was used in this study. Sublethal laser fluence was determined at 0.8J/cm(2) and used to stimulate normal human fibroblasts in monolayer culture. The results showed that there was no significant difference in collagen synthesis between the stimulated fibroblasts and controls. However, significant delay in collagen remodeling activity was demonstrated in the irradiated group by measuring fibroblast populated collagen lattice (FPCL) contraction. The stimulation of SCF, HGF and b-FGF gene expression was determined by RT-PCR analysis and demonstrated to vary between cases. Two out of six cell lineages that showed stronger responses to laser stimulation on SCF, HGF and b-FGF gene expressions were used to prepare conditioned media. The conditioned media from irradiated groups showed significant increase in SCF and b-FGF content and stimulated SK-mel-3 melanoma cells to synthesize more melanin in vitro. These results suggest that sublethal laser stimulation of fibroblasts may cause post-laser hyperpigmentation through production of melanogenic stimulatory cytokines. The degree of stimulation of SCF, HGF and b-FGF production varied between individual cell lineages, which may reflect the true variation of post-laser hyperpigmentation in clinical practice.

Melanoma cell migration is upregulated by tumour necrosis factor-alpha and suppressed by alpha-melanocyte-stimulating hormone

We reported recently that the inflammatory cytokine tumour necrosis factor α (TNF-α) can upregulate integrin expression, cell attachment and invasion of cells through fibronectin in a human melanoma cell line (HBL). Furthermore, the actions of TNF-α were suppressed by the addition of an anti-inflammatory peptide α-melanocyte-stimulating hormone (α-MSH). In the current study, we extend this work investigating to what extent TNF-α might stimulate melanoma invasion by promoting cell migration and whether α-MSH is also inhibitory. Two human melanoma cell lines were examined in vitro (HBL and C8161) using a scratch migration assay. Analysis using either time-lapse video microscopy or imaging software analysis of migrating ‘fronts’ of cells revealed that C8161 cells migrated more rapidly than HBL cells. However, when cells were stimulated with TNF-α both cell types responded with a significant increase in migration distance over a 16–26 h incubation time. α-Melanocyte-stimulating hormone had an inhibitory effect on TNF-α-stimulated migration for HBL cells, completely blocking migration at 10⁻⁹ M. In contrast, C8161 cells did not respond to α-MSH (as these cells have a loss-of-function melanocortin-1 receptor). However, stable transfection of C8161 cells with the wild-type melanocortin-1 receptor produced cells whose migration was significantly inhibited by α-MSH. In addition, the use of a neutralising antibody to the β₁-integrin subunit significantly reduced migration in both cell types. This data therefore supports an inflammatory environment promoting melanoma cell migration, and in addition shows that α-MSH can inhibit inflammatory stimulated migration. The data also support a fundamental role of the β₁-integrin receptor in melanoma cell migration.

In vitro study examining the effect of sub-lethal QS 755 nm lasers on the expression of p16INK4a on melanoma cell lines

BACKGROUND AND OBJECTIVES

Q-switched lasers had been used in the treatment of lentigo maligna but their role remains controversial. While previous studies have addressed the change in adhesion molecule expression after sub-lethal laser damage, no study has addressed the impact of sub-lethal laser damage at a molecular level. The p16 gene has been proposed as the candidate gene for melanoma. Our objective is to examine the effect of sub-lethal laser damage on p16 expression in melanoma cell lines.

STUDY DESIGN/MATERIALS AND METHODS

Three human melanoma cell lines-HTB 66, Sk-mel-24 (HTB 71), and G361-were irradiated by a Q-switched 755 nm Alexandrite laser at fluencies that ranged from 0.85 to 2.0 J/cm(2). HTB 66 was the only cell line with significant expression of p16INK4a while the other two cells lines were p16INK4a negative and served as negative control. Protein and mRNA expression for p16 were assessed by flow cytometry and RT-PCR, respectively.

RESULTS

The level of p16INK4a protein in cell line HTB 66 increased significantly after laser irradiation as compared with non-irradiated cells. The level of p16INK4a protein did not change in p16INK4a-negative cell lines (Sk-mel-24 and G361). However, there was only a slight increase in the percentage of G0/G1 phase cells.

CONCLUSIONS

Sub-lethal laser damage could increase DNA damage leading to an increase in p16 expression, and such effect would be particularly undesirable for patients with p16 mutation. Further studies are warranted to examine the role of sub-lethal laser damage in inducing p16 mutation.

Carbon dioxide laser dermabrasion for giant congenital melanocytic nevi

The management of giant congenital melanocytic nevi remains controversial. There is a balance to be achieved between minimizing the disfiguring appearance of these lesions, both before and after surgical treatment, and limiting the risk of malignant change. A series of seven patients who were treated in the same manner, with carbon dioxide laser dermabrasion, is presented. It has been 6 years since the first patient was treated in this way, and no cases of recurrence have been observed. This technique enables the removal of all or most of the pigmented lesion, with minimal scarring and without the need for disfiguring skin grafts. It has been well proved that there is an increased risk of malignant changes among patients with these lesions, although the amount of increased risk for the patient is not clear. Evidence from a review of the currently available literature is presented to indicate why this management method, at best, should decrease this risk and, at worst, should make no difference to the overall risk for individual patients.

Melanoma cell attachment, invasion, and integrin expression is upregulated by tumor necrosis factor alpha and suppressed by alpha melanocyte stimulating hormone

We have previously shown alpha-melanocyte stimulating hormone to protect melanocytes and melanoma cells from the proinflammatory actions of tumor necrosis factor-alpha. The aim of the study was to extend this work to look into the influence of tumor necrosis factor-alpha on melanoma cell attachment, invasion, and integrin expression and ask to what extent alpha-melanocyte stimulating hormone might protect cells from tumor necrosis factor-alpha stimulation of increased integrin expression. HBL human melanoma cells were studied under resting and stressed conditions using tumor necrosis factor-alpha as a proinflammatory cytokine. Functional information on the actions of tumor necrosis factor-alpha on melanoma cells was obtained by examining the strength of attachment of melanoma cells to substrates and the ability of melanoma cells to invade through fibronectin. alpha3, alpha4, and beta1 integrin expression was detected by Western immunoblotting and the ability of alpha-melanocyte stimulating hormone to oppose the actions of tumor necrosis factor-alpha was studied on HBL cell attachment, invasion, and integrin subunit expression. Our results show that tumor necrosis factor-alpha increases the number of melanoma cells attaching to collagen (types I and IV) and tissue culture polystyrene, increases ability to invade through fibronectin, and upregulates the expression of alpha3 (28%), alpha4 (90%), and beta1 (65%) integrin subunit expression. In contrast, alpha-melanocyte stimulating hormone reduced cell attachment, invasion, and integrin expression and opposed the stimulatory effects of tumor necrosis factor-alpha. In conclusion this study provides further evidence of alpha-melanocyte stimulating hormone acting to "protect" melanoma cells from proinflammatory cytokine action. Our data support a hypothesis that an inflammatory environment would promote melanoma invasion and that the anti-invasive actions of alpha-melanocyte stimulating hormone are consistent with its working in an anti-inflammatory capacity.

Changes in the levels of integrin and focal adhesion kinase (FAK) in human melanoma cells following 532 nm laser treatment

Despite the increase in laser therapy, concern remains that sublethal treatment of pre-malignant lesions may adversely affect the biological behaviour of surviving cells. Integrin receptors mediate interaction of cells with the extracellular matrix and their occupation leads to focal adhesion kinase (FAK) activation. Using our previously established model we have now investigated subcellular changes and compared integrin and FAK concentrations, the degree of FAK phosphorylation and its association with the beta1 integrin in laser vs. non-laser treated cells. We treated cells with laser generated from a frequency doubled Q-switched (Nd:YAG) laser system (532 nm) at 0.4 J/cm2 twice per week for 4 weeks. Using cell lysates we performed Western immunoblotting 24 hr later to detect integrin subunits and FAK proteins and immunoprecipitation to investigate FAK phosphorylation and its association with beta1. Cell morphology was examined using electron microscopy. SK23 and G361 cells exhibited an 3.4- and 11.2-fold increase, respectively, in FAK protein following laser treatment. FAK phosphorylation in SK23 cells was increased by 82%, whereas FAK phosphorylation in G361 cells was reduced slightly (2%). Furthermore, both alpha3 and 4 integrins were up-regulated, by approximately 4-fold and 7- to 9-fold, respectively. In addition, the beta1 integrin was proteolysed in both cell lines and the levels of FAK associated with beta1 was increased (2.1- and 2.7-fold, respectively). Finally, laser treatment of SK23 cells caused an increased number of cell processes. Sublethal 532 nm laser light thus induces changes in integrin and FAK concentrations and subsequently influences cellular attachment and morphology.