Related Experiment Videos
Early gene responses associated with transforming growth factor-beta 1 growth inhibition and autoinduction in MCF-7
1Laboratorie de Pharmacologie et Toxicologie Fondamentales, CNRS, Toulouse, France.
Abstract:
In the human breast carcinoma cell line (MCF-7), exogenous TGF-beta 1 induces a dose-dependent inhibition of cell proliferation. In a MCF-7 cell subline [MCF-7(-)], which has an undetectable level of type II TGF-beta receptor, exogenous TGF-beta 1 does not inhibit cell proliferation but is still able to induce its own message. In both cell lines, TGF-beta 1 stimulates expression of c-jun, whereas a rapid, transient and marked increase in c-fos mRNA is only observed in the MCF-7 cells sensitive to the growth inhibitory effect of TGF-beta 1. Depletion of protein kinase C abolishes the c-fos but not the c-jun response to TGF-beta 1. Our results suggest that growth inhibition and autoinduction by TGF-beta 1 are mediated by different signalling pathways. In addition, a PKC-dependent increase in c-fos expression seems to be associated with the growth inhibitory effect of TGF-beta 1.
Insights
Transforming growth factor-beta 1 (TGF-beta 1) inhibits breast cancer cell proliferation via distinct pathways. While c-jun is universally induced, c-fos induction, linked to growth inhibition, requires protein kinase C (PKC).
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Transforming growth factor-beta 1 (TGF-beta 1) is known to regulate cell proliferation and gene expression.
- The role of specific TGF-beta 1 signaling pathways in mediating its diverse cellular effects, including growth inhibition, is not fully elucidated.
- The MCF-7 human breast carcinoma cell line and its sublines offer a model to study differential responses to TGF-beta 1.
Purpose of the Study:
- To investigate the signaling pathways by which TGF-beta 1 inhibits cell proliferation in MCF-7 cells.
- To determine the role of the type II TGF-beta receptor in mediating TGF-beta 1's effects.
- To differentiate the signaling mechanisms responsible for TGF-beta 1-induced growth inhibition versus autoinduction.
Main Methods:
- Treatment of MCF-7 and MCF-7(-) cell lines with exogenous TGF-beta 1.
- Assessment of cell proliferation inhibition.
- Measurement of c-jun and c-fos mRNA expression using quantitative techniques.
- Depletion of protein kinase C (PKC) to assess its role in signaling pathways.
Main Results:
- Exogenous TGF-beta 1 dose-dependently inhibited proliferation in MCF-7 cells but not in MCF-7(-) cells lacking the type II TGF-beta receptor.
- TGF-beta 1 stimulated c-jun expression in both cell lines.
- A rapid, transient increase in c-fos mRNA was observed only in TGF-beta 1-sensitive MCF-7 cells.
- PKC depletion abolished the c-fos response but not the c-jun response to TGF-beta 1.
Conclusions:
- TGF-beta 1 utilizes distinct signaling pathways for growth inhibition and autoinduction.
- A protein kinase C (PKC)-dependent increase in c-fos expression is associated with the growth inhibitory effect of TGF-beta 1.
- The type II TGF-beta receptor is critical for mediating TGF-beta 1-induced growth inhibition.