C-RET Molecule in Malignant Melanoma from Oncogenic RET-Carrying Transgenic Mice and Human Cell Lines

Yuichiro Ohshima,Machiko Iida,Masashi Kato,Yoshinari Matsumoto,Kozue Takeda,Mayuko Kumasaka,Ichiro Yajima,Benjamin Edward Rich

doi:10.1371/journal.pone.0010279

Yuichiro Ohshima, Machiko Iida + Show 6 more

Open Access

https://doi.org/10.1371/journal.pone.0010279

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Journal: PloS one	Publication Date: Apr 21, 2010
Citations: 63	License type: CC BY 4.0

Affiliation: Chubu University, Aichi Medical University

Abstract

Malignant melanoma is one of the most aggressive cancers and its incidence worldwide has been increasing at a greater rate than that of any other cancer. We previously reported that constitutively activated RFP-RET-carrying transgenic mice (RET-mice) spontaneously develop malignant melanoma. In this study, we showed that expression levels of intrinsic c-Ret, glial cell line-derived neurotrophic factor (Gdnf) and Gdnf receptor alpha 1 (Gfra1) transcripts in malignant melanomas from RET-transgenic mice were significantly upregulated compared with those in benign melanocytic tumors. These results suggest that not only introduced oncogenic RET but also intrinsic c-Ret/Gdnf are involved in murine melanomagenesis in RET-mice. We then showed that c-RET and GDNF transcript expression levels in human malignant melanoma cell lines (HM3KO and MNT-1) were higher than those in primary cultured normal human epithelial melanocytes (NHEM), while GFRa1 transcript expression levels were comparable among NHEM, HM3KO and MNT-1. We next showed c-RET and GFRa1 protein expression in HM3KO cells and GDNF-mediated increased levels of their phosphorylated c-RET tyrosine kinase and signal transduction molecules (ERK and AKT) sited potentially downstream of c-RET. Taken together with the finding of augmented proliferation of HM3KO cells after GDNF stimulation, our results suggest that GDNF-mediated c-RET kinase activation is associated with the pathogenesis of malignant melanoma.

Highlights

It has recently been reported that the incidence of cutaneous malignant melanoma is increasing at a greater rate than that of any other cancer [1]
We examined whether c-RET/GNDF signaling worked in human malignant melanoma cells
Our results showed that transcript expression levels of c-RET and glial cell line-derived neurotrophic factor (GDNF) in MNT-1 and HM3KO human malignant melanoma were definitely higher than those in normal human epithelial melanocytes (NHEM) cells, while GFRa1 expression levels were comparable in these cells (Figure 4)

Summary

Introduction

It has recently been reported that the incidence of cutaneous malignant melanoma is increasing at a greater rate than that of any other cancer [1]. GDNF, which is structurally related to members of the transforming growth factor- ß (TGF-ß) superfamily, exerts its effect on target cells by binding to a glycosyl phosphatidylinositol (GPI)anchored cell surface protein (GFRa1), which, in turn, recruits the receptor tyrosine kinase c-RET to form a multi-subunit signaling complex. Formation of this complex results in c-RET autophosphorylation and a cascade of intracellular signaling including the extracellular signal-regulated kinase (ERK) and Akt kinase to regulate cell survival [2,3,4,5,6]. It has been shown that mutationally enhanced activity of cRET kinase caused the development of human carcinomas, including multiple endocrine neoplasia (MEN) and papillary thyroid carcinoma (PTC) [4,8]

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