Sestrin1, a tumor suppressor that can be rescued

Metformin Caused Radiosensitivity of Breast Cancer Cells through the Expression Modulation of miR-21-5p/SESN1axis

OBJECTIVE

In this research we evaluated molecular mechanism of effect of metformin in radio sensitivity of breast cancer cells.

METHODS

This research was done in cellular and molecular research center of Qazvin university of Medical science in 1399 to 1401. Studied samples were two breast cancer cell lines (MCF-7 and MDA-MB-231) they are derived from primary and secondary tumors resected from a single patient. We exposed them to cumulative 50 Gy radiation and constructed radio resistant cell lines. Then resistant cell lines were treated with 50µm of metformin. Our studied groups were resistant cells treated and un treated with metformin. Then, the expression rate of miR-21-5p and SESN1 gene in resistant and control cells was checked by Quantitative Real-time PCR(qRTPCR). After the cell lines were treated with different concentrations of metformin at different intervals, the rate of cell proliferation and cell death was checked by CCK-8 assay and flow cytometry. The Western blot method was also used to confirm the expression of some genes.

RESULTS

Our results showed that the expression of miR-21-5p was upregulated in radiation-resistant cancer cells (1.8±0.65) (P<0.0001) MCF-7 cell line and (1.6±0.42)(P<0.001) MBA-MD-231 cell line, while the expression of SESN1 was down regulated (0.46±0.12) (P<0.0001) MCF-7 cell line and (0.42±0.22) (P<0.001) MBA-MD-231 cell line. Metformin enhanced the radio sensitivity of breast cancer cells in a dose and time-dependent manner. Also, metformin treatment decreased the expression of miR-21-5p (0.47±0.32) (P<0.0001) MCF-7 Cell line and (0.45±0.21)(P<0.001) MBA-MD-231 cell line and increased the expression of SESN1 (1.65±0.72)(P<0.0001)MCF-7 cell line and (1.73±0.52)(P<0.0001) MBA-MD-231 cell line. The function of metformin was reversed by miR-21-5p inhibitors or the transfection of SESN1 overexpressing plasmids.

CONCLUSION

In conclusion, based on this research results, metformin enhanced the radio sensitivity of breast cancer cells via modulating  the expression of miR-21-5p and SESN1.

Sestrins as a Therapeutic Bridge between ROS and Autophagy in Cancer

The regulation of Reactive Oxygen Species (ROS) levels and the contribution therein from networks regulating cell metabolism, such as autophagy and the mTOR-dependent nutrient-sensing pathway, constitute major targets for selective therapeutic intervention against several types of tumors, due to their extensive rewiring in cancer cells as compared to healthy cells. Here, we discuss the sestrin family of proteins—homeostatic transducers of oxidative stress, and drivers of antioxidant and metabolic adaptation—as emerging targets for pharmacological intervention. These adaptive regulators lie at the intersection of those two priority nodes of interest in antitumor intervention—ROS control and the regulation of cell metabolism and autophagy—therefore, they hold the potential not only for the development of completely novel compounds, but also for leveraging on synergistic strategies with current options for tumor therapy and classification/stadiation to achieve personalized medicine.