Cancer Epithelial Cells Participate in the Self-Organization of Lung Tumor Spheroids: A Morphological Approach

The tumor microenvironment is known to play an important role in tumor progression. However, the specific mechanisms underlying this process are still not known in detail and more research is needed on the elements that control tumor progression in lung cancer. In this work, we aimed to investigate the involvement of epithelial and stromal cancer cells in growth, cell migration, and epithelial-to-mesenchymal transition (EMT) in a 3D in vitro model consisting of cell spheroids cultured in a type I collagen scaffold.

Spheroids were manufactured using different combinations of epithelial cells, particularly H460 and H1792 cell lines, with cancer-associated fibroblasts and normal fibroblasts, both isolated from adenocarcinoma patients. We evaluated the morphology of the spheroids by analysis of F-actin and pankeratin with confocal microscopy. We determined the ultrastructure of cells in the spheroids by transmission electron microscopy and the expression of CDH1, CDH2, and VIM by RT-PCR.

We observed that, on the one hand, the type of epithelial cell influences the morphology of spheroids. Stromal cells stimulated spheroid growth and cell dissemination through the collagen matrix, either alone or organized in branches with a nucleus of epithelial cells preceded by fibroblast cells. They also induced the appearance of new cell groups in the scaffold and the presence of EMT markers.

The results presented here indicate the participation of both epithelial and stromal cells in the control of spheroid self-organization. The experimental model proposed here, although preliminary, is useful for the study of some aspects related to tumor progression in lung cancer.