Ensuring diverse in vitro lung cancer models: Development of alveolar epithelial cell lines, patient-derived xenografts, and lung adenocarcinoma cell lines from individuals of African ancestry

Lung cancer disproportionately affects individuals of African ancestry (AA), particularly men, who experience 12% higher incidence and 15% higher death rates than European ancestry men. The causes of this disparity remain unclear; while smoking is the most substantial risk factor for lung cancer, AA men do not smoke more than other groups. Despite the lack of understanding of the increased lung cancer risk and death rates of the AA population, the tools to study lung cancer in this group lag far behind; there are very limited in vitro models to study lung cancer in AA individuals. Lung adenocarcinoma (LUAD), which originates in the alveolar epithelium, is the most common histological subtype of lung cancer in all population groups. Immortalized human alveolar epithelial cells (ihAEC) are therefore key tools for studying the etiology and development of LUAD, as well as effects of environmental exposures. In addition to ihAECs, patient-derived xenografts (PDXs), in which human tumors are implanted and grown in immunodeficient mice, and in vitro cultured LUAD cell lines, are valuable tools to study lung adenocarcinoma. To address the shortage of these models developed from AA patients, we are taking a 3-pronged approach. We are collecting non-tumor and LUAD tissues from AA lung cancer patients with full consent. When sufficient non-tumor tissue is available, we isolate alveolar epithelial cells and use a CRISPR/Cas9-based gene-delivery approach to generate ihAEC lines. We direct genomic integration of simian virus 40 large-tumor antigen (SV40 LgT) and human telomerase reverse transcriptase ( TERT ) genes into the adeno-associated virus integration site 1 (AAVS1), a safe harbor region that prevents inserted genes from being silenced. When sufficient LUAD tumor tissue is available, we implant tumor sections subcutaneously in immunodeficient mice. Tumors that grow are explanted for a new round of propagation in mice as well as in vitro culture. To date one PDX has been established, and cells are in culture from non-tumor and tumor tissue; further characterization is in progress. The development of new ihAEC lines, PDXs, and LUAD cell lines will provide valuable tools for studying responses to environmental exposures, carcinogen detoxification processes, oncogenic transformation, and for testing novel therapies in ancestry-appropriate models. This work is an important step towards minimizing lung cancer health disparities caused by the absence of diverse model systems. Supported by grants U54CA233396, U54CA233444, and U54CA233465 from the National Institutes of Health (NIH)/National Cancer Institute (NCI), and the Norris Comprehensive Cancer Center core grant, award number P30CA014089 from the NIH/NCI.