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Spheroid Assay to Measure TGF-β-induced Invasion
Published on: November 16, 2011
Isolation and characterization of transforming growth factor beta response variants from human prostatic tumor cell
1Department of Pathology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298.
Abstract:
In this study we examined the relation between the response to transforming growth factor beta (TGF beta 1) in vitro and the growth in vivo of 1-LN-PC3-1A (1-LN) human prostatic carcinoma cells. 1-LN cells resistant to the growth-inhibitory effects of TGF beta 1 were isolated after exposure to 2 ng/ml TGF beta 1 in an anchorage-independent growth assay. Cloning of TGF beta 1-resistant and -sensitive populations produced 2 clones (R2-6 and 1-LN clone 4), which maintained relatively stable resistance or sensitivity, respectively, in the absence of TGF beta 1 for up to 12 passages. Colony formation by the R2-6 cells in the presence of TGF beta 1 was 2-10 times greater than that of 1-LN clone 4, depending upon the TGF beta 1 concentration. Injection of 1 x 10(5) R2-6 cells into athymic nude mice produced tumors with a significantly shorter latency interval as compared with 1-LN clone 4 tumors (P < 0.0001). Western immunoblotting showed that higher levels of latent TGF beta 1 protein were secreted into the culture medium by 1-LN clone 4 cells. Acidified conditioned media from both clones inhibited mink lung epithelial cell DNA synthesis. Neutralizing monoclonal antibody to TGF beta 1 but not TGF beta 2 abrogated this inhibitory effect. Comparison of the different sensitive and resistant clones showed that in vitro sensitivity to TGF beta 1 and in vivo tumor latency interval were not invariably correlated. Thus, the TGF beta 1 response phenotype in vitro was not always predictive of growth delay in vivo.
Insights
This study found that prostate cancer cells resistant to transforming growth factor beta 1 (TGF-β1) in vitro did not always show slower tumor growth in vivo. TGF-β1 resistance in vitro does not reliably predict tumor latency in vivo.
Area of Science:
- Oncology
- Cell Biology
- Molecular Biology
Background:
- Transforming growth factor beta 1 (TGF-β1) is a key regulator of cell growth and differentiation.
- Prostate cancer progression is influenced by various growth factors, including TGF-β1.
- Understanding the relationship between TGF-β1 response and tumor growth is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the correlation between in vitro response to TGF-β1 and in vivo tumor growth of human prostatic carcinoma cells.
- To determine if TGF-β1 resistance in vitro predicts tumor latency in an animal model.
- To analyze TGF-β1 secretion levels in resistant and sensitive cell lines.
Main Methods:
- Isolation of 1-LN-PC3-1A (1-LN) human prostatic carcinoma cells resistant to TGF-β1.
- Cloning of TGF-β1-resistant (R2-6) and -sensitive (1-LN clone 4) cell populations.
- Assessment of colony formation in the presence of TGF-β1.
- Tumorigenicity assays in athymic nude mice.
- Western immunoblotting for latent TGF-β1 protein.
- Inhibition assays using conditioned media and neutralizing antibodies.
Main Results:
- TGF-β1-resistant R2-6 cells exhibited significantly greater colony formation than sensitive 1-LN clone 4 cells in vitro.
- R2-6 cells formed tumors with a shorter latency interval in nude mice compared to 1-LN clone 4 cells.
- 1-LN clone 4 cells secreted higher levels of latent TGF-β1 protein.
- Conditioned media from both clones inhibited mink lung epithelial cell DNA synthesis, an effect abrogated by anti-TGF-β1 antibody.
- In vitro TGF-β1 sensitivity did not invariably correlate with in vivo tumor latency.
Conclusions:
- The in vitro TGF-β1 response phenotype of prostate cancer cells is not always predictive of their in vivo tumor growth rate.
- TGF-β1 resistance in vitro does not necessarily translate to accelerated tumor growth in vivo.
- Further research is needed to elucidate the complex mechanisms governing TGF-β1's role in prostate cancer progression.
