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Updated: Oct 2, 2026
Assessment of Ovarian Cancer Spheroid Attachment and Invasion of Mesothelial Cells in Real Time
Published on: May 20, 2014
TGF beta-induced Smad signaling remains intact in primary human ovarian cancer cells
Lesley D Dunfield1, Elizabeth J Campbell Dwyer, Mark W Nachtigal
1Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4H7.
Abstract:
Disruptions in TGF beta signaling have been implicated in various human cancers, including ovarian cancer. Our goal was to determine whether ovarian cancer cells isolated from patient ascites fluid were growth inhibited by TGF beta 1 treatment and further characterize the expression and activity profile of TGF beta/Smad signaling components in human ovarian cancer cells. We found that 9 of 10 primary cultures of ovarian cancer cells (OC2-10) were growth inhibited by 16 pM TGF beta 1. One primary ovarian cancer sample (OC1) and the established ovarian cancer cell lines CaOV3 and SkOV3 continued to grow in the presence of TGF beta 1. All cells expressed components of the TGF beta/Smad signaling pathway including TGF beta 1, T beta RI, T beta RII, Smad2, -3, -4, and Smad anchor for receptor activation. Although OC1, CaOV3, and SkOV3 are not growth inhibited by TGF beta 1, they can transmit the TGF beta 1 signal to turn on a transfected TGF beta/Smad reporter gene, p3TP.lux. In addition, all cells up-regulate the endogenous TGF beta target genes Smad7 and PAI-1. p15(Ink4B) mRNA is also up-regulated with TGF beta 1 treatment in OC2-9, whereas the p15(Ink4B) gene has been deleted in OC1, CaOV3, and SkOV3 cells. Homozygous deletion of p15(Ink4B) may account for TGF beta resistance in some populations of ovarian cancer cells. Our data demonstrate that the TGF beta/Smad signaling pathway remains functional in human ovarian cancer cells and suggest that if abnormalities exist in the cellular response of TGF beta signals, they must lie downstream of the Smad proteins.
Insights
Most ovarian cancer cells show growth inhibition with TGF beta 1 treatment. However, some resistant cells may have p15(Ink4B) gene deletions, indicating downstream signaling is functional.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Transforming growth factor beta (TGF beta) signaling disruptions are linked to various human cancers.
- Ovarian cancer is a significant area of research concerning TGF beta pathway dysregulation.
Purpose of the Study:
- To investigate TGF beta 1 growth inhibition in primary ovarian cancer cells.
- To characterize the expression and activity of TGF beta/Smad signaling components in human ovarian cancer cells.
Main Methods:
- Primary ovarian cancer cells from ascites fluid were treated with TGF beta 1.
- Expression of TGF beta/Smad pathway components was analyzed.
- Reporter gene assays (p3TP.lux) and target gene expression (Smad7, PAI-1, p15(Ink4B)) were assessed.
Main Results:
- 90% of primary ovarian cancer cell cultures (OC2-10) exhibited growth inhibition by TGF beta 1.
- Resistant cell lines (OC1, CaOV3, SkOV3) showed functional TGF beta/Smad signaling, indicated by reporter gene activation and target gene induction (Smad7, PAI-1).
- Homozygous deletion of the p15(Ink4B) gene was observed in resistant cell lines (OC1, CaOV3, SkOV3), correlating with TGF beta resistance.
Conclusions:
- The TGF beta/Smad signaling pathway is generally functional in human ovarian cancer cells.
- TGF beta resistance in some ovarian cancer cells may be attributed to p15(Ink4B) gene deletion.
- Signaling abnormalities in TGF beta-resistant ovarian cancer cells likely occur downstream of Smad proteins.
