- Open Access
Non-thermal atmospheric pressure plasmas as a novel candidate for preventive therapy of melanoma
© The Japanese Society for Hygiene 2014
- Received: 25 June 2014
- Accepted: 3 July 2014
- Published: 19 July 2014
Due to the increased ultraviolet radiation, the incidence of melanoma is increasing worldwide more than that of any other cancer. In this study, the effects of irradiation of non-thermal atmospheric pressure plasmas (NEAPPs) on benign melanocytic tumors from our original hairless model mice (HL-RET-mice), in which benign melanocytic tumors and melanomas spontaneously develop in the skin stepwise, were examined. Expression levels of melanoma cell adhesion molecule (MCAM) and matrix metalloproteinase-2 (MMP-2) mRNA in melanomas were higher than those in benign melanocytic tumors in the mice. Repeated irradiation of non-thermal atmospheric pressure plasmas (NEAPPs) for the benign tumors decreased the expression levels of MCAM and MMP-2 mRNA in the tumors from the mice. Previous studies showed that MCAM sites are upstream of MMP-2, that MCAM regulates transcription of MMP-2 in melanoma cells and that MMP-2 is associated with the conversion of a benign tumor to a malignant tumor. Therefore, our results suggest that the NEAPP irradiation-mediated decrease in the expression level of MMP-2 in benign melanocytic tumors is associated with decreased expression levels of MCAM. Moreover, NEAPP irradiation might be a potential candidate for therapy to prevent melanoma development through suppression of malignant conversion in benign melanocytic tumors.
- mRNA Expression Level
- Benign Tumor
- Melanocytic Nevus
- Decrease Expression Level
The incidence of melanoma, the most aggressive skin cancer, is increasing worldwide more than that of any other cancer . However, effective therapies for preventing the development of melanoma are very limited. Thus, the establishment of effective therapies for melanoma is an important issue. We developed original hairless model mice carrying constitutively activated RET (HL-RET-mice), in which benign melanocytic tumors and melanomas spontaneously develop in the skin stepwise [1, 2]. The process of melanoma development in HL-RET-mice resembles the process of development of human large congenital melanocytic nevi, which are benign melanocytic tumors and might be a high risk factor for development of melanoma [1–3]. Previous studies showed that a mouse model might be a strong tool for the development of preventive therapies for melanoma [1, 2, 4].
Plasma consists of an ionized gas and is defined as the fourth state of matter. Recent medical research has focused on the application of non-thermal atmospheric pressure plasmas (NEAPPs) for cancer therapy. Previous in vitro and in vivo studies showed anti-tumor effects of NEAPP irradiation on cancers [4–7]. However, there is limited information on preventive effects of NEAPP irradiation on the process of malignant conversion from a benign tumor to a malignant tumor in vivo.
Our recent in vivo study showed that mRNA expression levels of matrix metalloproteinase-2 (MMP-2) in benign melanocytic tumors from HL-RET-mice were decreased by repeated NEAPP irradiation for 11 weeks after confirming that MMP-2 expression was increased in melanomas . A previous study showed that melanoma cell adhesion molecule (MCAM) sites are upstream of MMP-2 and that MCAM regulates transcription of MMP-2 via Id-1 in melanoma cells . Previous studies also showed that Ap-2 alpha, Sp-1 and Pax-3 are upstream of MCAM and regulate transcription of MCAM [9, 10]. Therefore, in this study we focused on MCAM as a regulator of MMP-2 expression and Ap-2 alpha, Sp-1 and Pax-3 as regulators of MCAM expression (Supplemental Figure 1).
This work was supported in part by Grants-in-Aid for Scientific Research (B) (No. 24390157 and 24406002), Grant-in-Aid for Challenging Exploratory Research (No. 23650241 and 2667052), Grant-in-Aid for Scientific Research on Innovative Areas (No. 24108001), COE projects for Private Universities (Nutritional Health Science Research Center, No. 1201007) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT); the Cosmetology Research Foundation; Toyoaki Scholarship Foundation; the Mitsui & Co., Ltd. Environment Fund; Aichi Health Promotion Foundation and Research foundation from Center for Advanced Medicine and Clinical Research in Nagoya University Hospital.
Conflict of interest
The authors have no conflict of interest to declare.
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