Chen et al. Journal of Experimental & Clinical Cancer Research 2010, 29:13 http://www.jeccr.com/content/29/1/13 R E S E A R C H Open Access In-vivo transfection of pcDNA3.1-IGFBP7 inhibits melanoma growth in mice through apoptosis induction and VEGF downexpression Rong-Yi Chen1,2†, Hong-Xiang Chen1†, Jia-Xi Lin2, Wei-Bing She1, Ping Jiang1, Li Xu1, Ya-Ting Tu1* Abstract Background: Genome-wide RNA interference screening study revealed that loss of expression of insulin-like growth factor binding protein 7 (IGFBP7) is a critical step in development of a malignant melanoma (MM), and this secreted protein plays a central role in apoptosis of MM. In this study we constructed pcDNA3.1-IGFBP7 to obtain high expression of IGBPF7 and to inhibit the growth of MM in C57BL/6J mice. Methods: pcDNA3.1-IGFBP7 was transfected into B16-F10 cell, the expression of IGFBP7 was detected by RT-PCR and western blot. The proliferations and apoptosis rates of transfected and control cells were measured by CCK8 and FCM, respectively. The tumorigenicity and tumor growth in both pcDNA3.1-IGFBP7 group and control groups were studied in C57BL/6J mice model. IGFBP7, caspase-3, and VEGF expressions in tumor tissue were measured by immunohistochemistry. Apoptosis of tumors were detected by TUNEL. Results: We demonstrated this plasmid inhibited proliferation of B16-F10 melanoma cells efficiently in vivo, exploiting the high expression of IGFBP7. More importantly, in-vivo transfection of pcDNA3.1-IGFBP7 inhibited MM growth in C57BL/6J mice. The inhibition of MM growth was proved owing to apoptosis and reduced expression of VEGF induced by pcDNA3.1-IGFBP7. Conclusions: These results suggest a potential new clinical strategy for MM gene treatment. Background MM is responsible for 80% of skin cancer deaths, and to date its incidence has been increasing. Although devel- opment of surgical, chemotherapeutic and radiothera- peutic treatment keeps ongoing, the 5-year survival rate of late stage MM patients is only 10-20% [1-4]. There- fore, a new effective therapy for MM is highly desired. In the previous studies, we demonstrated that the synth- esis of vascular endothelial growth factor (VEGF) and growth of MM in xenograf models [3] were significantly inhibited by using small-interfering RNA (siRNA), which makes us believe that the modulation of aberrant signaling pathways in MM cell will probably provide more effective and potential nontoxic therapy for MM. However, this approach still has its shortcomings, in * Correspondence: sunronarticles@yahoo.cn † Contributed equally 1Department of Dermatology, Affiliated Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022 PR China that VEGF is one of the downstream target genes of insulin-like growth factor (IGF), which is important in promoting tumor angiogenesis [5-8]. Although pU-VEGF-siRNA directly inhibited MM cell prolifera- tion by reducing VEGF expression, it could not induce valid apoptosis. Recently, immunohistochemical analysis of human skin, nevi, and melanoma samples implicates loss of IGFBP7 expression as a critical step in melanoma carci- nogenicity [9]. Thus, the relationship between IGF axis and carcinogenesis has become one of the hottest spots. The IGF system is composed of IGFs, IGF receptors, and Insulin-like growth factor-binding proteins (IGFBPs). IGFBP7 belongs to the IGFBP superfamilies. It is also known as IGFBP-related protein 1 (IGFBP-rP1) or Mac25. It is a member of soluble protein family that binds IGFs with low affinity, and is expressed in a wide range of tissues [10,11]. In-vitro studies demonstrated that IGFBP7 induced the apoptosis of many cancer cells [12,13], e.g., breast and prostate cancer cells, and plays a © 2010 Chen et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.