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Transient SNAIL1 expression is necessary for metastatic competence in breast cancer
Hung D Tran1, Krishna Luitel1, Michael Kim1
1Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri.
Abstract:
SNAIL1 has been suggested to regulate breast cancer metastasis based on analyses of human breast tumor transcriptomes and experiments using cancer cell lines and xenografts. However, in vivo genetic experimental support for a role for SNAIL1 in breast cancer metastasis that develops in an immunocompetent tumor microenvironment has not been determined. To address this question, we created a genetic SNAIL1 model by coupling an endogenous SNAIL1 reporter with an inducible SNAIL1 transgene. Using multiple genetic models of breast cancer, we demonstrated that endogenous SNAIL1 expression was restricted to primary tumors that ultimately disseminate. SNAIL1 gene deletion either during the premalignant phase or after primary tumors have reached a palpable size blunted metastasis, indicating that late metastasis was the main driver of metastasis and that this was dependent on SNAIL1. Importantly, SNAIL1 expression during breast cancer metastasis was transient and forced transient, but not continuous. SNAIL1 expression in breast tumors was sufficient to increase metastasis.
Insights
The study shows that the SNAIL1 gene drives breast cancer metastasis, even when tumors are advanced. Transient expression of SNAIL1 in primary tumors is sufficient to promote the spread of cancer.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- The transcription factor SNAIL1 is implicated in breast cancer metastasis.
- Previous studies relied on transcriptomic data and non-immunocompetent models.
- In vivo genetic evidence in an immunocompetent microenvironment was lacking.
Purpose of the Study:
- To genetically investigate the role of SNAIL1 in breast cancer metastasis in vivo.
- To determine if SNAIL1 is required for metastasis in an immunocompetent setting.
- To assess the impact of SNAIL1 expression timing and duration on metastasis.
Main Methods:
- Development of a genetic SNAIL1 reporter model coupled with an inducible SNAIL1 transgene.
- Utilized multiple genetic breast cancer models in an immunocompetent host.
- SNAIL1 gene deletion at different tumor progression stages; assessed metastasis.
Main Results:
- Endogenous SNAIL1 expression was specifically detected in primary tumors that disseminated.
- SNAIL1 gene deletion significantly reduced metastasis, regardless of timing (pre-malignant or established tumors).
- Transient SNAIL1 expression, but not continuous, was sufficient to drive metastasis.
Conclusions:
- SNAIL1 is a critical driver of late-stage breast cancer metastasis.
- The study provides in vivo genetic validation of SNAIL1's role in metastasis within a relevant microenvironment.
- Targeting transient SNAIL1 expression may offer a therapeutic strategy for preventing breast cancer spread.
