Background Immunocompetent animal models are required to study tumor-host interactions, immunotherapy, and immunotherapeutic combinations, however the currently available immunocompetent lung cancer models have substantial limitations. While orthotopic models potentially help fill this gap, the utility of these models has been limited by the very small number of murine lung cancer cell lines capable of forming orthotopic tumors in immunocompetent C57BL/6 hosts. Methods Primary lung tumors with specific genetic alterations were created in C57BL/6 background mice. These tumors were then passaged through other animals to increase tumorigenicity and select for the ability to grow in a non-self animal. Once tumors demonstrated growth in a non-self host, cell lines were established. Successful cell lines were evaluated for the ability to produce orthotopic lung tumors in immunocompetent hosts. Results We produced six murine lung cancer lines capable of orthotopic lung tumor formation in immunocompetent C57BL/6 animals. These lines demonstrate the expected genetic alterations based on their primary tumor genetics. Conclusions These novel cell lines will be useful for evaluating tumor-host interactions, the impact of specific oncogenic alterations on the tumor microenvironment, and immunotherapeutic approaches. This method of generating murine lines capable of orthotopic growth can likely be applied to other tumors and will broaden the applicability of pre-clinical testing of immunotherapeutic treatment regimens.
Objective Smad4 is a tumor suppressor that transduces transforming growth factor beta signaling and regulates genomic stability. We previously found that Smad4 knockdown in vitro inhibited DNA repair and increased sensitivity to DNA topoisomerase inhibitors. In this study, we assessed the association between reduced Smad4 expression and DNA topoisomerase inhibitor sensitivity in human non-small cell lung cancer (NSCLC) patients and evaluated the relationship between genomic alterations of Smad4 and molecular alterations in DNA repair molecules. Materials and Methods We retrospectively identified NSCLC patients who received etoposide or gemcitabine. Chemotherapeutic response was quantified by RECIST 1.1 criteria and Smad4 expression was assessed by immunohistochemistry. Relationships between Smad4 mutation and DNA repair molecule mutations were evaluated using publically available datasets. Results We identified 28 individuals who received 30 treatments with gemcitabine or etoposide containing regimens for NSCLC. Reduced Smad4 expression was seen in 13/28 patients and was not associated with significant differences in clinical or pathologic parameters. Patients with reduced Smad4 expression had a larger response to DNA topoisomerase inhibitor containing regimens then patients with high Smad4 expression (−25.7% vs. −6.8% in lesion size, p=0.03); this relationship was more pronounced with gemcitabine containing regimens. The overall treatment response was higher in patients with reduced Smad4 expression (8/14 vs 2/16 p=0.02). Analysis of data from The Cancer Genome Atlas revealed that Smad4 mutation or homozygous loss was mutually exclusive with genomic alterations in DNA repair molecules. Conclusions Reduced Smad4 expression may predict responsiveness to regimens that contain DNA topoisomerase inhibitors. That Smad4 signaling alterations are mutually exclusive with alterations in DNA repair machinery is consistent with an important role of Smad4 in regulating DNA repair.
tumors collected within 48 hours after death. Rapidly collected advanced or drug resistant tumors allows for the study of molecular basis of lung cancer. The purpose of this study was to report logistics, ethical implications, and results of a pilot RTD program at Moffitt Cancer Center (MCC). Physicians discussed RTD with advanced lung cancer patients. Consented patients' health was monitored and staff notified when patients entered hospice. Shortly after death the body was transported and retrievals were conducted by a medical examiner within 24-48 hours of death. Samples were frozen or preserved in formalin and stored by MCC Tissue Core. Results: Twenty patients consented to participate in RTD between 2015 and 2016. Seven patients died and their tissues collected including primary, metastatic and normal tissue, and blood samples. Logistical challenges included: high costs and variability per case depending on county of death and final arrangements; availability of autopsy facility, and hospice communication. Weekend deaths were challenging due to limited staff resources. Histology evaluation of metastatic samples demonstrated minimal postmortem damage, confirming RTD provides high quality tissue. Conclusions: There are logistical challenges in developing a RTD program, but with communication and coordination, this program can succeed. Collection of tissue through RTD is attainable and beneficial for cancer research.
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