Study on stem cell plasticity and niche remodeling during lung tumor development

Abstract

AT2 (alveolar epithelial progenitor) cells are known as the cell origin of LUAD (Lung adenocarcinoma). Mutant KRAS is commonly observed in LUAD patients. So far, research has focused on the plasticity of AT2 cells within LUAD. After KRAS oncogene activation, AT2 cells change to HPCS (High Plasticity Cell State) and further, cells with different transcriptional states have been observed. However, LUAD is a complex disease which has interactions between various types, and research about the interactions between tumor cells and their niche has not been conducted. To identify this, we need to observe the interactions by generating tumors in vivo using KPT tumor organoids. This approach is based on results showing that tumor formation occurred in NSG mice following organoid transplantation. This study aims to ensure that KPT tumor organoids exhibit characteristics similar to the tumors observed in KPT mice before organoid transplantation. We developed in vivo system using KPT mice and in vitro system using KPT tumor organoids. We induced lung tumor in KPT mice by inserting Adeo-Cre virus intrathecally. We identified the tumor morphology within lung tumors through hematoxylin and eosin staining. Also, we observed various cell states within the tumor according to immunofluorescence data. As previously reported in the study, cell heterogeneity was confirmed within tumor. In vitro system, we isolated tomato positive cells from the tumor region generated in KPT mice. We cultured Tomato expressing cells under feeder conditions and identified cell types. The results showed a decrease in the expression of SPC or pro-SPC, known AT2 cell markers, and an increase in the expression of Krt8, a DATP marker. While previous study has reported that KP organoids have Sox9 expression using single cell RNA sequencing, it was not confirmed. However, when cells cultured with stromal cells, Sox9 expression was detected. These findings suggest that KPT tumor cells can form in vivo tumors when moving to an in vivo environment, similar to co-culture conditions. Collectively, these results indicate that KPT tumor organoids exhibit features observed in tumors from KPT mice, supporting their potential as a valuable tool for organoid transplantation studies in future.