Unresectable locally advanced non-small cell lung cancer treated with concurrent platinum-based chemotherapy and thoracic radiation results in primary tumor recurrence in >35-80% of cases from radioresistant tumors. Therefore, research aimed at understanding mechanisms of radioresistance and strategies to overcome this problem are paramount to better lung cancer treatment outcomes. We found TWIST1 was commonly overexpressed in human lung cancers and Twist1 could confer radiation resistance to lung epithelial cells, lung cancer cells and autochthonous mouse lung tumors in vivo. Twist1 is a basic helix- loop-helix transcriptional factor. The domains of Twist1 and transcriptional targets of Twist1 that are required for radioresistance are unknown. In order to maximize the therapeutic potential of inhibiting Twist1 for lung cancer, we must precisely define the protein domains of Twist1 and/or the downstream transcriptional targets of Twist1 required for radioresistance. In the present proposal we have three specific aims to test two hypotheses that will provide more mechanistic insight into the structure-function relationships of Twist1 and lung cancer radioresistance. One central hypothesis of this proposal is that specific protein domains of Twist1 are required for radioresistance. We have developed a novel lung epithelium specific Twist1 mouse model and various mutant versions of Twist1 to facilitate these studies. Our second testable hypothesis is there is a defined set of "core" transcriptional targets of Twist1 required for radioresistance. The studies outlined in our proposal will provide valuable knowledge to the pathophysiologic role of Twist1 in lung cancer and Twist1- induced radioresistance. Finally, validating a novel preclinical inducible lung cancer model of radioresistance will create a model to test new treatments for this fatal disease in combination with radiation.
Specific Aim #1 : Characterize the domains of Twist1 required for radioresistance in vitro. We will use mouse embryo fibroblasts (MEFs) and isogenic human lung cancer cells expressing Twist1 and Twist1 mutants to examine which domains of Twist1 are necessary for a radioresistant phenotype. We will determine the cell autonomous mechanisms of Twist1-induced radioresistance in vitro.
Specific Aim #2 : Characterize the domains of Twist1 required for radioresistance of KrasG12D-induced autochthonous lung tumors. We will test this hypothesis with serial non-invasive imaging and confirm our findings with standard molecular-histologic methods to follow the response to radiation in our novel Twist1 transgenic lung tumor model. We will also examine the dominant mechanisms for Twist1-dependent radiation response modulation in vivo.
Specific Aim #3 : Determine Twist1 transcriptional targets correlated with Twist1-induced radioresistance using gene expression and ChIP-chip profiling. We will use integrative genome-wide bioinformatic approaches on MEFs and human lung cancer cells to isolate the "core" gene targets required for Twist1-induced radioresistance.

Public Health Relevance

The work we have proposed has a direct impact on the etiology and potential treatment of locally advanced lung cancer. As Twist1 is not typically expressed post-natally, therapies directed against Twist1 may be a more specific and perhaps less toxic therapy. Lastly, the study of Twist1 and EMT will allow a broader understanding of radioresistance in other tissues and may expose a new pathway to target radioresistance in general.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
Project #
Application #
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Ahmed, Mansoor M
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Johns Hopkins University
Schools of Medicine
United States
Zip Code
Shamir, Eliah R; Pappalardo, Elisa; Jorgens, Danielle M et al. (2014) Twist1-induced dissemination preserves epithelial identity and requires E-cadherin. J Cell Biol 204:839-56
Fan, Katherine Y; Dholakia, Avani S; Wild, Aaron T et al. (2014) Baseline hemoglobin-A1c impacts clinical outcomes in patients with pancreatic cancer. J Natl Compr Canc Netw 12:50-7
Sundi, Debasish; Wang, Vinson; Pierorazio, Phillip M et al. (2014) Identification of men with the highest risk of early disease recurrence after radical prostatectomy. Prostate 74:628-36
Belcaid, Zineb; Phallen, Jillian A; Zeng, Jing et al. (2014) Focal radiation therapy combined with 4-1BB activation and CTLA-4 blockade yields long-term survival and a protective antigen-specific memory response in a murine glioma model. PLoS One 9:e101764
Sengupta, Soma; Weeraratne, Shyamal Dilhan; Sun, Hongyu et al. (2014) *5-GABAA receptors negatively regulate MYC-amplified medulloblastoma growth. Acta Neuropathol 127:593-603
Tran, Phuoc T; Bivalacqua, Trinity J; Dicker, Adam P (2014) Adjuvant radiation for node-positive disease after prostatectomy: more good news, but who will listen? J Clin Oncol 32:3917-9
Alcorn, Sara R; Gocke, Christopher D; Woodard, Christopher A et al. (2014) Solitary plasmacytoma of the penile urethra treated with primary radiotherapy. J Clin Oncol 32:e95-7
Walker, Amanda J; Alcorn, Sara R; Narang, Amol K et al. (2013) Radiosensitizers in pancreatic cancer--preclinical and clinical exploits with molecularly targeted agents. Curr Probl Cancer 37:301-12
Gajula, Rajendra P; Chettiar, Sivarajan T; Williams, Russell D et al. (2013) The twist box domain is required for Twist1-induced prostate cancer metastasis. Mol Cancer Res 11:1387-400