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Establishment of a Conditional Transgenic Mouse Model Recapitulating EML4-ALK-Positive Human Non-Small Cell Lung
Kyoung Ho Pyo1, Sun Min Lim2, Hye Ryun Kim3
1Yonsei Cancer Research Institute, JE-UK Laboratory of Molecular Cancer Therapeutics, Seoul, Republic of Korea.
Background:
Anaplastic lymphoma receptor tyrosine kinase gene (ALK) fusion is a distinct molecular subclassification of NSCLC that is targeted by anaplastic lymphoma kinase (ALK) inhibitors. We established a transgenic mouse model that expresses tumors highly resembling human NSCLC harboring echinoderm microtubule associated protein like 4 gene (EML)-ALK fusion. We aimed to test an EML4-ALK transgenic mouse model as a platform for assessing the efficacy of ALK inhibitors and examining mechanisms of acquired resistance to ALK inhibitors.
Methods:
Transgenic mouse lines harboring LoxP-STOP-LoxP-FLAGS-tagged human EML4-ALK (variant 1) transgene was established by using C57BL/6N mice. The transgenic mouse model with highly lung-specific, inducible expression of echinoderm microtubule associated protein like 4-ALK fusion protein was established by crossing the EML4-ALK transgenic mice with mice expressing Cre-estrogen receptor fusion protein under the control of surfactant protein C gene (SPC). Expression of EML4-ALK transgene was induced by intraperitoneally injecting mice with tamoxifen. When the lung tumor of the mice treated with the ALK inhibitor crizotinib for 2 weeks was measured, tumor shrinkage was observed.
Results:
EML4-ALK tumor developed after 1 week of tamoxifen treatment. Echinoderm microtubule associated protein like 4-ALK was strongly expressed in the lung but not in other organs. ALK and FLAGS expressions were observed by immunohistochemistry. Treatment of EML4-ALK tumor-bearing mice with crizotinib for 2 weeks induced dramatic shrinkage of tumors with no signs of toxicity. Furthermore, prolonged treatment with crizotinib led to acquired resistance in tumors, resulting in regrowth and disease progression. The resistant tumor nodules revealed acquired ALK G1202R mutations.
Conclusions:
An EML4-ALK transgenic mouse model for study of drug resistance was successfully established with short duration of tumorigenesis. This model should be a strong preclinical model for testing efficacy of ALK TKIs, providing a useful tool for investigating the mechanisms of acquired resistance and pursuing novel treatment strategies in ALK-positive lung cancer.
Insights
A new transgenic mouse model effectively mimics human non-small cell lung cancer (NSCLC) with EML4-ALK fusion. This model aids in testing ALK inhibitors and understanding drug resistance mechanisms in ALK-positive lung cancer.
Area of Science:
- Oncology
- Genetics
- Pharmacology
Background:
- Anaplastic lymphoma receptor tyrosine kinase (ALK) fusion defines a subset of non-small cell lung cancer (NSCLC).
- ALK inhibitors are a targeted therapy for ALK-fusion-positive NSCLC.
- Echinoderm microtubule associated protein like 4 (EML4)-ALK fusion drives tumor formation in a subset of NSCLC patients.
Purpose of the Study:
- Establish a transgenic mouse model for EML4-ALK fusion-driven NSCLC.
- Utilize the model to assess the efficacy of ALK inhibitors.
- Investigate mechanisms of acquired resistance to ALK inhibitors.
Main Methods:
- Generated transgenic mice expressing a human EML4-ALK fusion gene in lung tissue.
- Induced tumor formation using tamoxifen.
- Administered the ALK inhibitor crizotinib to tumor-bearing mice and analyzed tumor response and resistance mechanisms.
Main Results:
- The EML4-ALK transgenic model rapidly developed lung tumors with high EML4-ALK expression.
- Crizotinib treatment induced significant tumor shrinkage without observable toxicity.
- Prolonged crizotinib treatment led to acquired resistance, characterized by tumor regrowth and the emergence of ALK G1202R mutations.
Conclusions:
- A novel EML4-ALK transgenic mouse model was successfully established for NSCLC research.
- This model is a valuable preclinical tool for evaluating ALK inhibitors and studying acquired resistance.
- The model facilitates the development of novel therapeutic strategies for ALK-positive lung cancer.
