Immortalized Human Mesothelial Cells-SV40

Effect of Glucose-Based PD Fluid and TGF-β1 on Mesothelial Cell miR-200c Expression

Peritoneal fibrosis and loss of transport function are common complications in long-term peritoneal dialysis (PD) patients, driven by epithelial-to-mesenchymal transition (EMT) in mesothelial cells. Dysregulation of microRNA (miR) expression is implicated in EMT and fibrosis.

Chu et al. investigated the role of miR-200c in EMT and fibrogenesis in mesothelial cells, using a murine PD model and cultured cells (immortalized human mesothelial cells), to understand its potential as a therapeutic target for peritoneal fibrosis. MiR-200c is expressed in mesothelial cells. Exposure to 1.36% glucose-based PD fluid Dianeal® resulted in a 21.8 ± 4.5% decrease in miR-200c levels compared to cells in serum-free medium (SFM) (Fig. 1A). TGF-β1 which promotes peritoneal fibrosis diminished miR-200c expression in a dose-responsive manner resulting in a 40.7% reduction at 10 ng/mL compared to SFM. MiR-200c repression resulted in lower E-cadherin and decorin expression while raising levels of mesenchymal markers ZEB2, Notch1, Jagged2, SNAIL, FSP-1, α-smooth muscle actin, fibronectin, and collagen I as shown in Figure 1. TGF-β1 did not affect vimentin expression. Mesenchymal markers and EMT transcription factors appeared within 24 hours of TGF-β1 treatment yet mesothelial cell phenotype changes emerged only after 48 hours (Fig. 1J). The application of decorin before TGF-β1 stimulation reduced TGF-β1's ability to suppress miR-200c expression (Fig. 1B).

Fig. 1. Effect of Dianeal® or TGF-β1 on Gene Expression of miR-200c and Mediators of EMT and Fibrosis in Mesothelial Cells (Chu J Y S, Chau M K M, et al., 2019).

Fcf Exposure Decreases Proliferation of Cells of Mesothelial Origin

Malignant mesothelioma (MM) is an aggressive cancer with limited treatment options and poor prognosis. Septin 7, a cytoskeleton protein, is implicated in MM progression. Blum et al. tested the effects of forchlorfenuron (FCF), a plant hormone that inhibits septin function, on MM cell lines and other tumor cell lines derived from various organs.

Human MSTO-211H cells derived from a biphasic MM, growing in vitro and exposed to FCF at concentrations ranging from 6.25 µM to 200 µM; cell proliferation was monitored using the Incucyte live-cell imaging system (Fig. 2). Results showed FCF exposure decreases proliferation of cells of mesothelial origin. For comparison of effects in MM cells vs. non-transformed mesothelial cells we included the two immortalized non-tumorigenic cell lines Met-5A and LP9/TERT-1. IC₅₀ values were higher in immortalized human mesothelial cells (Met-5A) and LP9/TERT-1 cells (76 and 62 µM, respectively) than in MM cell lines, indicative of a lower sensitivity of non-transformed mesothelial cells to the growth-inhibiting/cytotoxic effects of FCF. On average, epithelioid MM-derived cells (H28, ZL55, JL-1, H226) showed a slightly higher sensitivity to FCF than most MM cells derived from biphasic MM (MSTO-211H, SPC111, SPC212) or the sarcomatoid MM-derived ZL34 cells. This is in line with the observation that patients diagnosed with a sarcomatoid MM are in general more resistant to the first-line chemotherapy consisting of cisplatin and pemetrexed treatment.

Fig. 2. Proliferation-inhibiting effect of FCF in cells of mesothelial origin (Blum W, Henzi T, et al., 2019).