Abstract 677: EML4-ALK fusion gene expressing transgenic mouse for lung cancer model

Abstract

Abstract Background: EML4-ALK is a fusion-type protein typrosin kinase that is generated in lung cancer. We have established transgenic mouse line. The surfactant protein C gene (SPC) is only expressed in alveolar epithelial cells. We applied SPC promoter on encoded human-EML4-ALK gene. Normally, EML4-ALK gene is silenced when LoxP-PGK-LoxP gene is turned on. When Cre recombinase is present with the specific inducer, tamoxifen, EML4-ALK gene is expressed in alveolar epithelial cell, and converses to lung cancer. Materials and Methods: For generation of EML4-ALK fusion transgenic mouse, a cDNA fragment encoding FLAG tagged EML4-ALK (variant 1) was ligated to end of the CMV-LoxP-PGK-LoxP. The expression cassette was injected into pronuclear-stage embryos of B6 mouse to generate Tg mouse. Transgenic mouse was prepared for interbreed with KI mouse (SPC-CreER2T-trTA-NeoR). The KI-Tg fusion mouse was confirmed by genotyping, then the mouse was injected with tamoxifen (cre recombinase inducer) intraperitoneally. The lung tumors were observed by MRI or CT. The lung pathology was analyzed by immunohistochemistry and hematoxylin & eosin staining. For confirmation of EML4-ALK protein expression, western blot was performed in different organs. EML4-ALK tumor-bearing mouse was treated with ALK tyrosine kinase inhibitor (TKI) for 2 weeks and tumor shrinkage was measured. Results: EML4-ALK tumor was observed after one week. Tumor nodules were widely observed in all lung lobes. Pathologically, the histologic type was adenocarcinoma and had homology to patient tissue on H&E stain. We confirmed EML4-ALK expression in different organs including lung, heart, liver, stomach, kidney, colon and brain. EML4-ALK (120kDa) was strongly expressed in lung, but not in other organs. Indeed, ALK and Flag expression were observed in tumor region by immunohistochemistry. The EML4-ALK tumor bearing mice were treated with ALK TKI for 2 weeks. The ALK TKI-treated mice showed dramatic shrinkage of tumors and showed gain in body weight. Conclusions: EML4-ALK Tg mouse was successfully established. The benefits of the model compared to a previous conditioned Tg mouse model are (1) no need to treat Cre inducer daily, and (2) short duration (approximately 1 week) of tumorigenesis. We confirmed dramatic tumor shrinkage after treatment with ALK TKI. This model provides a strong preclinical model for testing ALK TKIs in lung cancer. Citation Format: Kyoung-Ho Pyo, Hye Ryun Kim, Sun Min Lim, Mi Ran Yun, Sung-Moo Kim, Hwan Kim, Han Na Kang, Ji Min Lee, Sang Gyun Kim, Byoung Chul Cho. EML4-ALK fusion gene expressing transgenic mouse for lung cancer model. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 677.