3D Co-culture of Lung Cancer Cells with CAFs: An In Vitro Model System to Study Tumor Progression

- In 3D co-cultures, multiple cell types are grown together in matrices like a basement membrane matrix, that mimics the natural extracellular matrix microenvironment, facilitating cell-cell and cell-matrix interactions. To establish an embedded 3D co-culture prepare a uniform suspension of cancer-associated fibroblasts or CAFs and lung cancer cells taken in two is to one ratio, in the basement membrane matrix. Maintain the suspension on ice to prevent matrix solidification at ambient temperatures.

Transfer an appropriate volume of suspension into a cell culture plate. Incubate at 37 degrees Celsius for the required duration to co-embed the cells in the matrix. To establish an overlaid 3D co-culture, prepare a suspension of lung cancer cells in basement membrane matrix, in the desired cell density. Maintain the suspension on ice. Pipette an appropriate volume of this cell-matrix suspension into a cell culture plate. Incubate at 37 degrees Celsius to set up the embedded cancer cell monoculture.

Subsequently transfer the desired volume of CAFs suspended in preferred culture media, over the embedded cancer cells. In 3D co-cultures, CAFs enhance cancer cells spheroid formation and attract cancer cells, resulting in tear-drop like structures. In this protocol, we will co-culture TUM622 lung cancer cells and CAFs to study their interaction.

- After preparing cell suspensions of TUM622 and CAFs, as previously described, count the CAF cell density by mixing 10 microliters of cell suspension with 10 microliters of trypan blue. Add 10 microliters of the mixture to each of the two chambers on a hemocytometer to count and calculate cell density. To co-embed TUM622 cells and CAFs in basement membrane matrix, first calculate the desired number of cells used for plating, based on the cell density information. CAFs are seeded at a 2 to 1 ratio of TUM622 cells. Transfer the calculated volume of TUM622, as well as CAF cells suspension, into the same centrifuge tube. Spin down and aspirate all medium. Resuspend in basement membrane matrix and plate 310 microliters of the mixture into each well of a 24 well plate. For immunofluorescence, transfer a 60 microliters of TUM622 and CAF mixtures to chamber slides as described previously.

To co-culture TUM622 with overlaid CAFs in basement membrane matrix, first set up TUM622 monoculture as previously described. Transfer twice the number of CAF suspension into a centrifuge tube and spin down at 300 times 'g' for five minutes at room temperature. Aspirate the supernatant and resuspend the CAFs in one milliliter of 3D culture medium. Transfer the one milliliter CAF suspension into the well containing the embedded TUM622 cells.