Egidy Giorgia, Julé Sophia, Bossé Philippe, Bernex Florence, Geffrotin Claudine, Vincent-Naulleau Silvia, Horak Vratislav, Sastre-Garau Xavier, Panthier Jean-Jacques
INRA, UMR955 Génétique Moléculaire et Cellulaire; Laboratoire conventionné CEA n degree 17; Ecole Nationale Vétérinaire d'Alfort, 7 avenue du Général de Gaulle, Maisons-Alfort, F-94704 France.
Mol Cancer. 2008 Apr 28;7:34. doi: 10.1186/1476-4598-7-34.
Metastatic melanoma is a severe disease. Few experimental animal models of metastatic melanoma exist. MeLiM minipigs exhibit spontaneous melanoma. Cutaneous and metastatic lesions are histologically similar to human's. However, most of them eventually spontaneously regress. Our purpose was to investigate whether the MeLiM model could reveal markers of malignancy in human melanocytic proliferations.
We compared the serial analysis of gene expression (SAGE) between normal pig skin melanocytes and melanoma cells from an early pulmonary metastasis of MeLiM minipigs. Tag identification revealed 55 regulated genes, including GNB2L1 which was found upregulated in the melanoma library. In situ hybridisation confirmed GNB2L1 overexpression in MeLiM melanocytic lesions. GNB2L1 encodes the adaptor protein RACK1, recently shown to influence melanoma cell lines tumorigenicity. We studied the expression of RACK1 by immunofluorescence and confocal microscopy in tissues specimens of normal skin, in cutaneous and metastatic melanoma developped in MeLiM minipigs and in human patients. In pig and human samples, the results were similar. RACK1 protein was not detected in normal epidermal melanocytes. By contrast, RACK1 signal was highly increased in the cytoplasm of all melanocytic cells of superficial spreading melanoma, recurrent dermal lesions and metastatic melanoma. RACK1 partially colocalised with activated PKCalphabeta. In pig metastases, additional nuclear RACK1 did not associate to BDNF expression. In human nevi, the RACK1 signal was low.
RACK1 overexpression detected in situ in human melanoma specimens characterized cutaneous and metastatic melanoma raising the possibility that RACK1 can be a potential marker of malignancy in human melanoma. The MeLiM strain provides a relevant model for exploring mechanisms of melanocytic malignant transformation in humans. This study may contribute to a better understanding of melanoma pathophysiology and to progress in diagnosis.
转移性黑色素瘤是一种严重疾病。转移性黑色素瘤的实验动物模型很少。MeLiM小型猪会自发产生黑色素瘤。其皮肤和转移性病变在组织学上与人类相似。然而，它们中的大多数最终会自发消退。我们的目的是研究MeLiM模型是否能揭示人类黑素细胞增殖中的恶性标志物。
我们比较了正常猪皮肤黑素细胞与来自MeLiM小型猪早期肺转移的黑色素瘤细胞之间的基因表达序列分析（SAGE）。标签鉴定揭示了55个调控基因，其中包括在黑色素瘤文库中上调的GNB2L1。原位杂交证实了MeLiM黑素细胞病变中GNB2L1的过表达。GNB2L1编码衔接蛋白RACK1，最近研究表明其会影响黑色素瘤细胞系的致瘤性。我们通过免疫荧光和共聚焦显微镜研究了正常皮肤组织标本、MeLiM小型猪和人类患者发生的皮肤及转移性黑色素瘤中RACK1的表达。在猪和人类样本中，结果相似。在正常表皮黑素细胞中未检测到RACK1蛋白。相比之下，在浅表扩散性黑色素瘤、复发性皮肤病变和转移性黑色素瘤的所有黑素细胞的细胞质中，RACK1信号显著增加。RACK1与活化的PKCalphabeta部分共定位。在猪转移瘤中，额外的核RACK1与BDNF表达无关。在人类痣中，RACK1信号较低。
在人类黑色素瘤标本中原位检测到的RACK1过表达是皮肤和转移性黑色素瘤的特征，这增加了RACK1可能成为人类黑色素瘤恶性标志物的可能性。MeLiM品系为探索人类黑素细胞恶性转化机制提供了一个相关模型。本研究可能有助于更好地理解黑色素瘤的病理生理学并推动诊断方面的进展。
