Characterization of cells cultured from chylous effusion from a patient with sporadic lymphangioleiomyomatosis.

Background: Lymphangioleiomyomatosis (LAM) is a progressive, rare interstitial lung disease that almost exclusively affects women. It is caused by a mutation in one of the tuberous sclerosis genes, TSC1 or TSC2, and constitutive activation of the mammalian target of rapamycin (mTOR) pathway in smooth muscle-like cells (LAM cells). The heightened proliferation and accumulation of LAM cells leads to the destruction of lung tissue.

Materials And Methods: In the present study, we developed a cell line (S-LAM1) derived from a chylous effusion obtained from a patient with sporadic, pulmonary LAM and evaluated its phenotype using immunofluorescence, flow cytometry, and an image stream system. Ultrastructure was assessed using a transmission electron microscope. To assess the ability of LAM cells to move and migrate (which is strictly associated with the ability to metastasize), we carried-out a real-time polymerase chain reaction (PCR) array analysis of 84 genes involved in cell motility. In order to evaluate the effect of rapamycin, a natural inhibitor of mTOR kinase, on S-LAM1 cells, a sulforhodamine B cell viability assay was performed with different concentrations of rapamycin.

Results And Conclusion: The phenotype of these cells is consistent with the biology of LAM cells. S-LAM1 cells present combined smooth muscle, melanocytic, and lymphatic endothelium lineage, as well as the presence of mesenchymal differentiation markers. A particular pattern of gene expression, including high expression of ezrin (EZR), myosin heavy chain 10, non-muscle (MYH10), and myosin light chain kinase (MYLK) and a greatly decreased expression of supervillin (SVIL), when compared to controls, indicates a high potential motility activity, especially of cell spreading. Rapamycin significantly, although only partially, inhibited S-LAM1 cell proliferation in vitro, and should, perhaps, be considered in the future in combination with other agents.