Differential response of normal and transformed mammary epithelial cells to combined treatment of anti-miR-21 and radiation

Abstract

Purpose: MicroRNA miR-21 has emerged as a therapeutic target in the treatment of breast cancer. This study was designed to compare the responses of breast cancer cells and non-transformed breast epithelial cells to a combined regimen of miR-21 inhibition and radiation.

Materials and methods: The MDA-MB-361 (breast cancer) and MCF-10A (non-transformed mammary epithelial) cell lines were used for the comparison in this in vitro study. The stable knockdown of miR-21 was performed by using lentiviral approach. The response of the cells was monitored 4, 24 and 48 h after the irradiation with 0.25 and 2.5 Gy, using sham-irradiated cells as controls. The response of the cells was established by performing various functional assays – cell viability and cell attachment, clonogenic survival, cell cycle analysis and 3D microtissue formation.

Results: The knockdown of miR-21 induced significant increase in apoptosis and growth delay in MDA-MB-361 cancer cells compared to non-transformed MCF-10A cells. After combined radiation and anti-miR-21 treatment, MDA-MB-361 cells show reduced cell growth and viability what is presented in their inability to form colonies. MCF-10A cells were not as sensitive to the combined treatment and that has also been confirmed with colony forming assay.

Conclusions: Cellular response to a combined treatment of anti-miR-21 and radiation is different between cancer and non-cancer cells which highly support the idea of linking miR-21 inhibitor and radiation treatment in the future therapeutic approaches for breast cancer.

Keywords:

• Cellular response
• MCF-10A
• miR-21
• radiation oncology

Acknowledgements

The authors thank Rosemarie Kell for excellent technical assistance and Janine König for using her pictures of MDA-MB-361 cells. This work was supported by the EURATOM Fission, European Commission 7th Framework Programme, Dark.Risk project (contract number 323216).

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.