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Escape from the antiproliferative effect of transforming growth factor-beta 1 in LLC-PK1 renal epithelial cells
R J Anderson1, H T Sponsel, D J Kroll
1Department of Medicine, Denver Veterans Affairs Medical Center, Colorado.
Abstract:
Transforming growth factor-beta 1 (TGF-beta 1) usually inhibits proliferation of epithelial cells. We find that LLC-PK1 renal tubular epithelial cells develop rapid in vitro resistance to the inhibitory effects of TGF-beta 1 and subsequently proliferate in response to TGF-beta 1. This unique response to TGF-beta 1 is not observed in another renal tubular epithelial cell line (MDCK cells). The proliferative response to TGF-beta 1 is additive to that produced by other growth factors. The proliferative response to TGF-beta 1 occurs despite an effect of TGF-beta 1 to suppress epidermal growth factor stimulated c-myc mRNA as determined by Northern analyses. These results suggest that LLC-PK1 cells develop rapid resistance to TGF-beta 1 inhibition of proliferation in vitro and that this resistance occurs despite continued suppression of c-myc mRNA.
Insights
Renal tubular epithelial cells (LLC-PK1) rapidly gain resistance to transforming growth factor-beta 1 (TGF-beta 1) inhibition, leading to proliferation. This response is unique to LLC-PK1 cells and occurs despite TGF-beta 1 suppressing c-myc mRNA.
Area of Science:
- Cell Biology
- Molecular Biology
- Renal Physiology
Background:
- Transforming growth factor-beta 1 (TGF-beta 1) typically inhibits epithelial cell proliferation.
- Understanding cellular responses to growth factors is crucial in renal physiology.
Purpose of the Study:
- To investigate the response of LLC-PK1 renal tubular epithelial cells to TGF-beta 1.
- To determine if LLC-PK1 cells develop resistance to TGF-beta 1's inhibitory effects.
- To compare the response of LLC-PK1 cells to MDCK cells.
Main Methods:
- In vitro cell culture of LLC-PK1 and MDCK cells.
- Treatment with TGF-beta 1 and other growth factors.
- Northern blot analysis to assess c-myc mRNA levels.
Main Results:
- LLC-PK1 cells rapidly acquired resistance to TGF-beta 1-induced proliferation inhibition in vitro.
- LLC-PK1 cells proliferated in response to TGF-beta 1, unlike MDCK cells.
- TGF-beta 1 suppressed epidermal growth factor-stimulated c-myc mRNA in LLC-PK1 cells, despite the proliferative response.
Conclusions:
- LLC-PK1 cells exhibit rapid in vitro resistance to TGF-beta 1's antiproliferative effects.
- This resistance occurs independently of TGF-beta 1's impact on c-myc mRNA expression.
- The findings highlight a unique cellular plasticity in LLC-PK1 cells regarding TGF-beta 1 signaling.