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Published on: October 27, 2020
Nuclear SMAD2 restrains proliferation of glioblastoma
1Department of Neurosurgery, the First People's Hospital of ZunYi, ZunYi, China.
Aims:
Although TGFβ receptor signaling has been shown to play a role in regulation of the growth and metastasis of glioblastoma multiforme (GBM), the downstream pathway through either SMAD2 or SMAD3 has not been elucidated. In this study, we investigate whether nuclear SMAD2 can restrain the proliferation of glioblastoma.
Methods:
A total of 23 resected specimens from GBM patients were collected for SMAD2 detection. Human GBM cell line A172, U87mg, D341m and Hs683 were maintained in Dulbecco's modified Eagle's medium and transfected with SMAD2 and SMAD3 shRNA plasmids. Gene expression was detected by RT-qPCR and Western and cell growth were detected by MTT assay.
Results:
Our results showed that the phosphorylated SMAD2 (pSMAD2, the nuclear and functional form of SMAD2) levels in GBM were significantly lower than the paired normal brain tissue in patients. Depletion of SMAD2, but not SMAD3, significantly abolished the inhibitory effects of TGFβ1 on the growth of GBM cells, possibly through pSMAD2-mediated increases in cell-cycle inhibitor, p27.
Conclusion:
Our data suggest that TGFβ/SMAD2 signaling cascades restrains growth of GBM.
Insights
Nuclear SMAD2 restrains glioblastoma growth. Lower levels of phosphorylated SMAD2 (pSMAD2) in glioblastoma multiforme (GBM) suggest a loss of this growth-inhibitory pathway, impacting cell proliferation.
Area of Science:
- Oncology
- Molecular Biology
- Cell Signaling
Background:
- Transforming Growth Factor beta (TGFβ) receptor signaling influences glioblastoma multiforme (GBM) growth and metastasis.
- The specific downstream pathway involving SMAD2 or SMAD3 in GBM remains unclear.
Purpose of the Study:
- To investigate the role of nuclear SMAD2 in restraining glioblastoma proliferation.
- To elucidate the downstream signaling pathway of TGFβ receptor in GBM.
Main Methods:
- Analyzed SMAD2 levels in 23 GBM patient specimens.
- Utilized human GBM cell lines (A172, U87mg, D341m, Hs683) with SMAD2 and SMAD3 shRNA transfection.
- Assessed gene expression via RT-qPCR and Western blot, and cell growth using MTT assay.
Main Results:
- Phosphorylated SMAD2 (pSMAD2) levels were significantly lower in GBM tissues compared to normal brain tissue.
- SMAD2 depletion, not SMAD3, abrogated TGFβ1's inhibitory effect on GBM cell growth.
- This inhibition may involve pSMAD2-mediated upregulation of the cell-cycle inhibitor p27.
Conclusions:
- The TGFβ/SMAD2 signaling pathway acts as a growth suppressor in glioblastoma.
- Nuclear SMAD2 plays a crucial role in controlling GBM cell proliferation.
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