Research

Genetically Engineered Mouse Models (GEMMs) to Study Cancer and Radiation Biology

Our laboratory uses GEMMs to model cancer because the tumors develop in their native microenvironment in animals with an intact immune system to closely resemble the natural history of human tumors. These advantages over traditional transplanted tumor models make GEMMs ideal preclinical platforms to dissect mechanisms of tumor biology and develop novel treatments. We have pioneered the development of spatially and temporally restricted mouse models of cancer using Cre-LoxP technology, dual recombinase technology, and CRISPR/Cas9 genome editing. We have used these models to study metastasis, to develop intraoperative molecular imaging, and to dissect the mechanisms of tumor and stromal cells to radiation therapy. We have also used GEMMs to reveal mechanisms by which the p53 tumor suppressor protein regulates acute toxicity and late effects of radiation therapy in specific cell types.

                                                     

Torok JA, Oh P, Castle KD, Reinsvold M, Ma Y, Luo L, Lee CL, Kirsch DG . Deletion of ATM in tumor but not endothelial cells improves radiation response in a primary mouse model of lung adenocarcinoma. Cancer Research. 2018 Oct 12. doi: 10.1158/0008-5472.CAN-17-3103. PMID:30315114

Huang J, Chen M, Whitley MJ, Kuo HC, Xu ES, Walens A, Mowery YM, Van Mater D, Eward WC, Cardona DM, Luo L, Ma Y, Lopez OM, Nelson CE, Robinson-Hamm JN, Reddy A, Dave SS, Gersbach CA, Dodd RD, Kirsch DG. Generation and comparison of CRISPR-Cas9 and Cre-mediated genetically engineered mouse models of sarcoma. Nature Communications. 2017 Jul 10;8:15999. PMCID:PMC5508130

Whitley MJ, Cardona DM, Spasojevic I, Ferrer JM, Cahill J, Lee CL, Snuderl M, Blazer DG 3rd, Hwang SE, Greenup RA, Mosca PJ, Mito JK, Cuneo KC, Larrier NA, O’Reilly EK, Riedel RF, Eward WC, Strasfeld DB, Fukumura D, Jain RK, Lee WD, Griffith LG, Bawendi MG, Kirsch DG, Brigman BE. A Mouse-Human Phase I Co-Clinical Trial of the Protease-Activatable Fluorescent Probe LUM015 for Intraoperative Imaging of Cancer. Science Translational Medicine. 2016 Jan 6; 8(320): 320ra4.  PMCID:PMC4794335

Moding EJ, Castle KD, Perez BA, Oh P, Min HD, Norris H, Ma Y, Cardona DM, Lee CL, Kirsch DG. Tumor Cells, but not Endothelial Cells, Mediate Eradication of Primary Sarcomas by Stereotactic Body Radiation Therapy. Science Translational Medicine.  2015 Mar 11;7(278): 278ra34. PMCID:PMC4360135

Moding EJ, Lee CL, Castle KD, Oh P, Mao L, Zha S, Min HD, Ma Y, Das S, Kirsch DG. Atm deletion with dual recombinase technology preferentially radiosensitizes tumor endothelium. Journal of Clinical Investigation. 2014 Aug;124(8):3325-38. PMCID:PMC4109553

Lee CL, Moding EJ, Cuneo KC, Li Y, Sullivan JM, Mao L, Washington I, Jeffords LB, Rodrigues RC, Ma Y, Das S, Kontos CD, Kim Y, Rockman HA, Kirsch DG.  p53 Functions in Endothelial Cells to Prevent Radiation-Induced Myocardial Injury in Mice. Science Signaling. 2012 Jul 24; 5(234). PMCID:PMC3533440

Kirsch DG, Santiago PM, di Tomaso E, Sullivan JM, Hou WS, Dayton T, Jeffords LB, Sodha P, Mercer KL, Cohen R, Takeuchi O, Korsmeyer SJ, Bronson RT, Kim CF, Haigis KM, Jain RK, Jacks T.  p53 Controls Radiation-Induced Gastrointestinal Syndrome in Mice Independent of Apoptosis. Science. 2010 Jan 29; 327(5965):593-6. PMCID:PMC2897160

Kirsch DG, Dinulescu DM, Miller JB, Grimm J, Santiago PM, Young NP, Nielsen GP, Quade BJ,  Chaber CJ, Schultz CP, Takeuchi O, Bronson RT, Crowley D, Korsmeyer SJ, Yoon SS, Hornicek FJ, Weissleder R, Jacks, T.  A Spatially and Temporally Restricted Mouse Model of Soft Tissue Sarcoma.  Nature Medicine. 2007;13:992-997.*=equal contribution. PMID:17676052

Current Research Projects in the Kirsch Lab Include:

Mechanisms of Response and Resistance to Radiation and Immune Checkpoint Blockade

Since the initial clinical trials of immune checkpoint blockade in patients with melanoma, immunotherapy, such as anti-programmed cell death protein 1 (PD-1), has been approved for many cancers and demonstrated impressive responses in some patients. However, the majority of cancer patients fail to respond to immune checkpoint blockade alone. In preclinical studies of mouse tumors transplanted into syngeneic mice, numerous investigators have reported dramatic responses to immune checkpoint blockade combined with radiation therapy, but these tumor models do not develop in a native microenvironment under immunosurveillance. Although genetically engineered mouse models (GEMMs) of cancer do co-evolve with a native immune system, these tumors have a very low number of somatic mutations. Therefore, they express limited neoantigens and generally do not engage effector T cells. To overcome the limitations of both transplant and GEMM models for studying immunotherapy, we have generated a novel autochthonous mouse model of high mutational load sarcoma initiated by deletion of p53 and a chemical carcinogen.  Using this novel highly mutated autochthonous tumor model, we are investigating mechanisms by which primary tumors respond or are resistant to immunotherapy and radiation therapy.  We are also testing whether this treatment combination not only improves local control of the irradiated tumor, but also the subsequent development of lung metastasis. This work has the potential to lead to new approaches to activate the immune system and prevent the development of metastasis.

Defining a Genetic Signature for Radiation-Induced Cancer

Radiation-induced sarcomas are a significant clinical problem because treatment of the normal tissue with a second course of radiation therapy increases the risk of a serious radiation-related toxicity. It is difficult to determine whether a second cancer that arises in a patient after radiation therapy is a new primary tumor, a recurrence of the original tumor, or a radiation-induced cancer. Because of this uncertainty, clinically the term “radiation-associated” is utilized rather than “radiation-induced”. To define a genetic signature of radiation-induced cancer, we are performing whole exome sequencing of mouse sarcomas that develop after focal, high dose radiation therapy.  We are comparing the genetic signature to our other mouse models of sarcoma induced by Cre recombinase and/or carcinogens.  We are also seeking to identify gene mutations in sarcomas that arise specifically after radiation therapy.

Sensitizing Brainstem Glioma to Radiation Therapy

Diffuse intrinsic pontine glioma (DIPG), also referred to as high-grade brainstem glioma, is a pediatric cancer that accounts for the majority of deaths from brain tumors in children. Radiotherapy is the standard of care for DIPG, as the anatomic location of the tumor precludes surgery and no chemotherapeutic agents have shown efficacy over radiation alone. Despite routine treatment with radiotherapy, fewer than 10% of patients survive two years from diagnosis. Using established GEMMs of brainstem glioma with different tumor suppressor genes, we are applying the Cre-loxP system to delete kinases in the tumor cells that we hypothesize will radiosensitize brainstem gliomas and improve survival after radiotherapy.

Other Research Projects Include:

  • Mechanisms by which the tumor suppressor p53 prevents cancer
  • Mechanisms by which the tumor suppressor ATRX prevents cancer
  • Mechanisms by which FUS-CHOP drives the development of cancer and radiosensitivity
  • Mechanisms of metastasis
  • Mechanisms of normal tissue injury after radiation
  • Cancer metabolism and radiation response
  • Epigenetic Regulators of Tumorigenesis