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TGM2 inhibition attenuates ID1 expression in CD44-high glioma-initiating cells
Jun Fu1, Qun-ying Yang, Ke Sai
1Corresponding Author: Zhong-ping Chen, MD, PhD, Department of Neurosurgery/Neuro-oncology, Cancer Center, Sun Yat-Sen University, Guangzhou 510060, China. chenzp57@mail.sysu.edu.cn.
Background:
CD44 is a molecular marker associated with cancer stem cell populations and treatment resistance in glioma. More effective therapies will result from approaches aimed at targeting glioma cells high in CD44.
Methods:
Glioma-initiating cell lines were derived from fresh surgical glioblastoma samples. Expression of tissue transglutaminase 2 (TGM2) was attenuated through lentivirus-mediated short hairpin RNA knockdown. MTT assay [(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] was used to evaluate the growth inhibition induced by TGM2 inhibitor. Terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling was used to evaluate cell apoptosis following TGM2 inhibition. CD44(+) glioma stem cells were sorted by flow cytometry. A nude mice orthotopic xenograft model was used to evaluate the in vivo effect of TGM2 inhibitor.
Results:
TGM2 was highly expressed in CD44-high glioblastoma tissues and tumor-derived glioma-initiating cell lines. TGM2 knockdown impaired cell proliferation and induced apoptosis in CD44-high glioma-initiating cell lines. Further studies indicated that expression of inhibitor of DNA binding 1 protein (ID1) is regulated by TGM2 and might be an important mediator for TGM2-regulated cell proliferation in CD44-high glioma-initiating cell lines. TGM2 inhibitor reduces ID1 expression, suppresses cell proliferation, and induces apoptosis in CD44-high glioma-initiating cell lines. Furthermore, TGM2 is highly expressed in CD44(+) glioma stem cells, while pharmacological inhibition of TGM2 activity preferentially eliminates CD44(+) glioma stem cells. Consistently, TGM2 inhibitor treatment reduced ID1 expression and induced apoptosis in our orthotopic mice xenograft model, which can be translated into prolonged median survival in tumor-bearing mice.
Conclusions:
TGM2 regulates ID1 expression in glioma-initiating cell lines high in CD44. Targeting TGM2 could be an effective strategy to treat gliomas with high CD44 expression.
Insights
Targeting tissue transglutaminase 2 (TGM2) effectively eliminates CD44-high glioma stem cells by reducing inhibitor of DNA binding 1 (ID1) expression. This approach offers a promising strategy for treating aggressive gliomas.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Stem Cell Research
Background:
- CD44 is a key marker for glioma stem cells and treatment resistance.
- Targeting CD44-high glioma cells is crucial for developing more effective therapies.
Purpose of the Study:
- To investigate the role of tissue transglutaminase 2 (TGM2) in CD44-high glioma cells.
- To evaluate the therapeutic potential of targeting TGM2 in glioma.
Main Methods:
- Glioma-initiating cell lines were established from glioblastoma samples.
- TGM2 expression was reduced using short hairpin RNA (shRNA).
- Cell proliferation, apoptosis, and in vivo tumor growth were assessed using MTT assays, TUNEL staining, flow cytometry, and xenograft models.
Main Results:
- TGM2 is highly expressed in CD44-high glioblastoma and glioma-initiating cells.
- TGM2 inhibition suppressed proliferation and induced apoptosis in CD44-high cells.
- TGM2 regulates inhibitor of DNA binding 1 (ID1) expression, a mediator of proliferation.
- Pharmacological inhibition of TGM2 preferentially eliminated CD44(+) glioma stem cells and prolonged survival in mice.
Conclusions:
- TGM2 plays a critical role in regulating ID1 expression in CD44-high glioma cells.
- Targeting TGM2 represents a viable therapeutic strategy for gliomas with high CD44 expression.
