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Tumor-suppressor activity of RRIG1 in breast cancer
Guihong Zhang1, Abenaa Brewster, Baoxiang Guan
1Department of Clinical Cancer Prevention, The University of Texas M D Anderson Cancer Center, Houston, Texas 77030, USA.
Background:
Retinoid receptor-induced gene-1 (RRIG1) is a novel gene that has been lost in several types of human cancers. The aim of this study was to determine whether RRIG1 plays a role in breast cancer, such as in the suppression of breast cancer cell growth and invasion.
Methods:
Immunohistochemistry was used to detect RRIG1 expression in breast tissue specimens. Gene transfection was used to restore or knock down RRIG1 expression in breast cancer cell lines for analysis of cell viability, colony formation, and migration/invasion potential. Reverse-transcription polymerase chain reaction and western blot assays were used to detect the changes in gene expression. The RhoA activation assay was used to assess RRIG1-induced inhibition of RhoA activity.
Results:
The immunohistochemical data showed that RRIG1 expression was reduced in breast cancer tissues compared with normal and atypical hyperplastic breast tissues. RRIG1 expression was inversely correlated with lymph node metastasis of breast cancer but was not associated with the status of hormone receptors, such as estrogen receptor, progesterone receptor, or HER2. Furthermore, restoration of RRIG1 expression inhibited proliferation, colony formation, migration, and invasion of breast cancer cells. Expression of RRIG1 also reduced phosphorylated Erk1/2 and Akt levels; c-Jun, MMP9, and Akt expressions; and RhoA activity. In contrast, knockdown of RRIG1 expression promoted breast cancer cell proliferation, colony formation, migration, and invasion potential.
Conclusion:
The data from the current study indicated that RRIG1 expression was reduced or lost in breast cancer and that restoration of RRIG1 expression suppressed breast cancer cell growth and invasion capacity. Future studies will determine the underlying molecular mechanisms and define RRIG1 as a tumor-suppressor gene in breast cancer.
Insights
Retinoid receptor-induced gene-1 (RRIG1) is often lost in breast cancer. Restoring RRIG1 suppresses tumor growth and invasion, suggesting it acts as a tumor suppressor.
Area of Science:
- Oncology
- Molecular Biology
- Gene Expression
Background:
- Retinoid receptor-induced gene-1 (RRIG1) is a novel gene frequently lost in human cancers.
- RRIG1 loss is observed in various cancer types, prompting investigation into its role in tumorigenesis.
Purpose of the Study:
- To investigate the role of RRIG1 in breast cancer.
- To determine if RRIG1 suppresses breast cancer cell growth and invasion.
Main Methods:
- Immunohistochemistry to assess RRIG1 expression in breast tissues.
- Gene transfection to manipulate RRIG1 levels in breast cancer cell lines.
- Assays for cell viability, proliferation, migration, invasion, and RhoA activity.
Main Results:
- RRIG1 expression is significantly reduced in breast cancer tissues compared to normal tissues.
- Restoring RRIG1 inhibited breast cancer cell proliferation, migration, and invasion, while reducing RhoA activity.
- Knockdown of RRIG1 enhanced these aggressive phenotypes.
Conclusions:
- RRIG1 expression is downregulated in breast cancer.
- Restoration of RRIG1 suppresses breast cancer cell growth and invasion, identifying it as a potential tumor suppressor.
- Further research is needed to elucidate RRIG1's molecular mechanisms in breast cancer.
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