The effects of PK11195 on the MCF-7 and T47D were associated with the allopregnanolone biosynthesis, which was mediated by Translocator Protein 18 KDa.

Breast cancer is currently the most common malignancy affecting women worldwide. It had been shown that the allopregnanolone biosynthesis was associated with tumorigenesis and PK11195, the Translocator Protein 18 KDa (TSPO) antagonist, had the effects of the allopregnanolone biosynthesis. However, little is known about the association between the effects of PK11195 on the breast cancer and the allopregnanolone biosynthesis. To evaluate this, the breast cancer cell lines MCF-7 and T47D were cultured. Cell viability and proliferation were determined by CCK-8 assay. The IC50 of PK11195 on the MCF-7 and T47D were 5.4 nM and 6 nM. The cell viability and proliferation of AC-5216 (TSPO selective ligand, 3 and 6 nM) was blocked by PK11195 (5.4 nM and 6 nM). Moreover, we evaluated the role of allopregnanolone biosynthesis in the effects of TSPO on breast cancer. Enzyme-Linked ImmunoSorbent Assay (ELISA) was used in the measurement of the allopregnanolone level. We found that the allopregnanolone level was increased by AC-5216 (3 and 6 nM) and the increase was reversed by PK11195 (5.4 nM and 6 nM, resepectively) in MCF-7 and T47D. The TSPO mRNA level was determined by real time polymerase chain reaction (PCR). The TSPO mRNA level were increased by AC-5216 (6 nM), which the increases were reversed by PK11195 (5.4 nM and 6 nM, resepectively) in MCF-7 and T47D. Collectedly, it firstly indicated that the effects of PK11195 on MCF-7 and T47D were associated with the decrease of allopregnanolone biosynthesis, which was mediated by TSPO.