Rapid target gene validation in complex cancer mouse models using re-derived embryonic stem cells

Our plain-English summary of Rapid target gene validation in complex cancer mouse models using re-derived embryonic stem cells, by I.J. Huijbers, R. Bin Ali, C. Pritchard, et al (EMBO Molecular Medicine, 2014).

The study

• Authors: I.J. Huijbers, R. Bin Ali, C. Pritchard, M. Cozijnsen, M.C. Kwon, N. Proost, J.Y. Song, H. de Vries, J. Badhai, K. Sutherland, P. Krimpenfort, E.M. Michalak, J. Jonkers, A. Berns
• Journal: EMBO Molecular Medicine
• Published: 2014;6(2):212-25
• Cited by: 77 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Human cancers modeled in Genetically Engineered Mouse Models (GEMMs) can provide important mechanistic insights into the molecular basis of tumor development and enable testing of new intervention strategies. The inherent complexity of these models, with often multiple modified tumor suppressor genes and oncogenes, has hampered their use as preclinical models for validating cancer genes and drug targets. In our newly developed approach for the fast generation of tumor cohorts we have overcome this obstacle, as exemplified for three GEMMs; two lung cancer models and one mesothelioma model. Three elements are central for this system; (i) The efficient derivation of authentic Embryonic Stem Cells (ESCs) from established GEMMs, (ii) the routine introduction of transgenes of choice in these GEMM-ESCs by Flp recombinase-mediated integration and (iii) the direct use of the chimeric animals in tumor cohorts. By applying stringent quality controls, the GEMM-ESC approach proofs to be a reliable and effective method to speed up cancer gene assessment and target validation. As proof-of-principle, we demonstrate that MycL1 is a key driver gene in Small Cell Lung Cancer.

In plain English

This was a laboratory study in genetically engineered mice at the Netherlands Cancer Institute. It did not study asbestos or any fiber. The authors developed a faster way to make mouse cancer models. They grew embryonic stem cells from existing engineered mouse strains, added new genes to those cells, and used the resulting part-engineered (chimeric) mice directly in experiments. They tested this in two lung cancer models and one mesothelioma model. In the mesothelioma model, tumors were triggered by injecting a virus into the chest that switched off the Nf2 and Trp53 genes. The authors reported that tumor type, incidence and timing were the same in chimeric and conventional mice for the small cell lung cancer and mesothelioma models. All chimeric mesothelioma-model mice developed invasive mesotheliomas. Small cell lung cancer chimeras that carried an added Mycl1 gene had a median survival of 167 days, compared with 250 days for chimeras without it. The authors concluded that the method performed well and could speed up the making and adapting of mouse models.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Animal experiment developing and testing a method (re-derived embryonic stem cells and chimeric mice) in genetically engineered mouse models of cancer
• Who was studied: Laboratory mice: wild-type strains and three genetically engineered models (non-small cell lung cancer, small cell lung cancer, mesothelioma), Netherlands Cancer Institute. 47 embryonic stem cell clones were derived from 364 embryos.
• Exposure: No asbestos or fiber exposure. Tumors were induced by a Cre-carrying adenovirus (Ad5-Cre) that switched engineered genes. It was given into the windpipe for the lung models and into the chest for the mesothelioma model (Nf2, Trp53 and Cdkn2a mutant mice). An added Mycl1 gene was tested in the small cell lung cancer model.
• Main results:
  • In the small cell lung cancer and mesothelioma models, tumor type, incidence and latency were identical between conventional and chimeric mice
  • All chimeric mice from the mesothelioma model developed epithelioid, sarcomatoid or biphasic mesotheliomas that invaded nearby tissues
  • In the mesothelioma model with a light-emitting (luciferase) reporter gene, all but one chimera developed mesothelioma with a signal in the chest, but the signal rose only to a limited degree over time
  • Small cell lung cancer chimeras with the added Mycl1 gene had a median survival of 167 days, compared with 250 days for chimeras with the reporter gene only
  • In first-generation (F1) offspring, median survival was 235 days with the reporter gene only and 140 days with the added Mycl1 gene
  • Mycl1 was amplified in 37.5 to 66.7% of control tumors, but in only 6% of tumors from mice with the added Mycl1 gene
• The authors' conclusion: The authors concluded that the method performed well and could be used routinely to speed up the making and adapting of mouse models
• Limitations the authors state:
  • Estimating how much of a chimeric mouse comes from the engineered cells by its coat color overestimated the true contribution in tissues
  • The cause of the limited reporter signal in the mesothelioma model remained speculative
  • The non-small cell lung cancer chimeric group came from a single stem cell clone, which may have picked up an unidentified genetic change

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: STEM, Tumor Suppressor Gene, Lung Cancer, Mesothelioma, Small Cell Lung Cancer.

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