Ouabain Promotes Gap Junctional Intercellular Communication in Cancer Cells
Mauricio Serrano-Rubi1, Lidia Jimenez1, Jacqueline Martinez-Rendon1
1Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, CDMX C.P. Mexico City 07360, Mexico.
Abstract:
Gap junctions are molecular structures that allow communication between neighboring cells. It has been shown that gap junctional intercellular communication (GJIC) is notoriously reduced in cancer cells compared to their normal counterparts. Ouabain, a plant derived substance, widely known for its therapeutic properties on the heart, has been shown to play a role in several types of cancer, although its mechanism of action is not yet fully understood. Since we have previously shown that ouabain enhances GJIC in epithelial cells (MDCK), here we probed whether ouabain affects GJIC in a variety of cancer cell lines, including cervico-uterine (CasKi, SiHa and Hela), breast (MDA-MB-321 and MCF7), lung (A549), colon (SW480) and pancreas (HPAF-II). For this purpose, we conducted dye transfer assays to measure and compare GJIC in monolayers of cells with and without treatment with ouabain (0.1, 1, 10, 50 and 500 nM). We found that ouabain induces a statistically significant enhancement of GJIC in all of these cancer cell lines, albeit with distinct sensitivity. Additionally, we show that synthesis of new nucleotides or protein subunits is not required, and that Csrc, ErK1/2 and ROCK-Rho mediate the signaling mechanisms. These results may contribute to explaining how ouabain influences cancer.
Insights
Ouabain, a plant-derived compound, significantly enhances gap junctional intercellular communication (GJIC) in various cancer cells. This effect occurs without new protein synthesis and involves specific signaling pathways, offering potential insights into cancer therapy.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Gap junctions are crucial for cell-to-cell communication.
- Reduced gap junctional intercellular communication (GJIC) is a hallmark of cancer.
- Ouabain, known for cardiac effects, has a poorly understood role in cancer.
Purpose of the Study:
- To investigate the effect of ouabain on GJIC in diverse cancer cell lines.
- To explore the underlying molecular mechanisms of ouabain's action on GJIC.
Main Methods:
- Dye transfer assays were used to measure GJIC.
- Multiple human cancer cell lines (cervical, breast, lung, colon, pancreas) were tested.
- Cells were treated with varying concentrations of ouabain.
Main Results:
- Ouabain significantly enhanced GJIC in all tested cancer cell lines.
- The enhancement showed distinct concentration-dependent sensitivity across cell types.
- Signaling pathways involving Csrc, ErK1/2, and ROCK-Rho were identified as mediators.
Conclusions:
- Ouabain effectively modulates GJIC in various cancer cells.
- The mechanism does not require de novo protein or nucleotide synthesis.
- These findings provide a basis for understanding ouabain's influence on cancer progression and potential therapeutic applications.
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