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Transforming growth factor-beta receptors in human cancer cell lines: analysis of transcript, protein and
S B Jakowlew1, T W Moody, J M Mariano
1National Cancer Institute, Medicine Branch, Rockville, Maryland 20850, USA.
Abstract:
Transforming growth factor-beta (TGF-beta) is a growth regulator which affects multiple cellular functions through the TGF-beta type I and type II receptor (TGF-beta RI and TGF-beta RII) serine/threonine kinases. In this study, the expression of TGF-beta RI and RII was investigated by northern blot, reverse transcription-polymerase chain reaction (RT-PCR) and western blot analyses in human breast (MCF-7 and T-47D), ovary (CP70 and OVT2) and prostate (LNCaP, DU145 and PC3) cancer cell lines. Northern blot analysis showed expression of TGF-beta RI and TGF-beta RII mRNAs in all cell lines examined except for MCF-7 and LNCaP, respectively. In contrast, RT-PCR showed that all of the cell lines examined express TGF-beta RI and RII transcripts using specific primer oligonucleotides. Western blot analysis demonstrated that all of the cancer cell lines examined express TGF-beta RI and RII proteins. Southern blot analysis showed there were differences in the restriction enzyme digestion patterns for TGF-beta RI and RII of T47D compared to MCF-7, PC3 and LNCaP. Also, the addition of TGF-beta 1 to the breast and prostate cancer cells inhibited colony formation in soft agarose. Our studies show that in cancer cells, relatively low levels of TGF-beta receptor transcripts may result in protein production and inhibition of cell proliferation by TGF-beta.
Insights
Transforming growth factor-beta (TGF-beta) receptors are expressed in various cancer cells. Despite low transcript levels, TGF-beta protein production can inhibit cancer cell proliferation.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Signaling
Background:
- Transforming growth factor-beta (TGF-beta) regulates cellular functions via TGF-beta type I and type II receptors (TGF-beta RI and TGF-beta RII).
- Dysregulation of TGF-beta signaling is implicated in various cancers.
Purpose of the Study:
- To investigate the expression of TGF-beta RI and TGF-beta RII in human breast, ovary, and prostate cancer cell lines.
- To determine the correlation between TGF-beta receptor expression and TGF-beta's effect on cancer cell proliferation.
Main Methods:
- Northern blot, reverse transcription-polymerase chain reaction (RT-PCR), and western blot analyses were used to assess TGF-beta receptor mRNA and protein expression.
- Southern blot analysis was performed to detect differences in receptor gene patterns.
- Soft agarose colony formation assays were conducted to evaluate the effect of TGF-beta 1 on cancer cell proliferation.
Main Results:
- Northern blot revealed TGF-beta RI and RII mRNA in most cell lines, with exceptions noted.
- RT-PCR confirmed TGF-beta RI and RII transcript expression in all examined cell lines.
- Western blot demonstrated TGF-beta RI and RII protein expression in all tested cancer cell lines.
- TGF-beta 1 inhibited colony formation in breast and prostate cancer cells.
- Southern blot indicated variations in TGF-beta RI and RII restriction enzyme digestion patterns among cell lines.
Conclusions:
- Cancer cells express TGF-beta RI and RII proteins, even with low transcript levels.
- TGF-beta signaling can inhibit proliferation in breast and prostate cancer cells.
- TGF-beta receptor expression and gene structure may vary across different cancer types.