CLDN6 Suppresses Migration and Invasion of MCF-7 and SKBR-3 Breast Cancer Cells by Blocking the SMAD/Snail/MMP-2/9 Axis
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Updated: Jul 19, 2025
Impedance-based Real-time Measurement of Cancer Cell Migration and Invasion
Published on: April 2, 2020
1Basic Pathology Department, Pathology College, Qiqihar Medical University, Qiqihar City, Heilongjiang Province, China.
Abstract:
The study examined the mechanisms of action of signal protein claudin 6 (CLDN6) on migration and invasion of breast cancer cell lines MCF-7 and SKBR-3. To this end, the signal proteins SMAD were blocked with their inhibitor SB431542, the genes CLDN6 and SNAIL were knocked down with short hairpin RNAs, and MMP2 and MMP9 were inhibited with TIMP-1. Expressions of MMP2 and MMP9 mRNAs were evaluated by reverse transcription PCR, Expressions of MMP-2, MMP-9, E-cadherin, N-cadherin, and vimentin were examined by Western blotting. Migration and invasion were analyzed by scratch test and Matrigel invasion assay. SB431542 inhibited expression of MMP2 and MMP9 in both cell lines. Single use of SB431542 inhibited expression of MMP-2/MMP-9 and corresponding mRNAs, but subsequent silencing of CLDN6 gene reversed this effect. TIMP-1 reversed down-regulation of E-cadherin, upregulation of N-cadherin and vimentin, facilitation of migration and invasion evoked by CLDN6 knocking down. Silencing of SNAIL gene inhibited migration and invasion, upregulated the expression of E-cadherin, and down-regulated expression of MMP2, MMP 9, N-cadherin, and vimentin. Thus, CLDN6 suppresses the epithelial-mesenchymal transition, migration, and invasion via blocking SMAD/Snail/MMP-2/9 signaling pathway in MCF-7 and SKBR-3 cancer cell lines.
Insights
Claudin 6 (CLDN6) protein suppresses breast cancer cell migration and invasion by inhibiting the SMAD/Snail/MMP-2/9 pathway. This finding offers new insights into breast cancer progression mechanisms.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Biology
Background:
- Claudin 6 (CLDN6) is a signal protein implicated in cell signaling pathways.
- Understanding CLDN6's role in breast cancer progression is crucial for developing targeted therapies.
- Breast cancer cell migration and invasion are key processes in metastasis.
Purpose of the Study:
- To investigate the molecular mechanisms by which CLDN6 influences the migration and invasion of MCF-7 and SKBR-3 breast cancer cell lines.
- To elucidate the involvement of the SMAD/Snail/MMP-2/9 signaling pathway in CLDN6-mediated effects.
Main Methods:
- Utilized SB431542 to inhibit SMAD signaling, short hairpin RNAs for CLDN6 and SNAIL gene knockdown, and TIMP-1 to inhibit MMP2 and MMP9.
- Assessed gene and protein expression via reverse transcription PCR and Western blotting.
- Analyzed cell migration and invasion using scratch and Matrigel invasion assays.
Main Results:
- SB431542 inhibited MMP2 and MMP9 expression; CLDN6 knockdown reversed this effect.
- TIMP-1 counteracted CLDN6 knockdown-induced changes in E-cadherin, N-cadherin, and vimentin, and reversed migration/invasion facilitation.
- SNAIL gene silencing reduced migration/invasion and modulated key protein expressions.
Conclusions:
- CLDN6 acts as a suppressor of epithelial-mesenchymal transition, migration, and invasion in breast cancer.
- The observed effects are mediated through the inhibition of the SMAD/Snail/MMP-2/9 signaling pathway.
- Findings highlight CLDN6 as a potential therapeutic target in breast cancer treatment.
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