Possible TLR-mediated immunostimulatory effect of Palbociclib in breast cancer

Palbociclib, which exerts its effect by inhibiting the cell cycle in cancer cells, is a CDK inhibitor used in the treatment of ER+/HER- breast cancer. In this study, we aimed to investigate the effect of Pablosiklib on TLR, which plays an important role in the immune response, in MCF-7 (ER+/HER2-) and MDA-MB-231 (ER-/PR-/HER2-) cell lines.

The expression levels of TLR 1-10 genes, cell cycle-related genes (CDK4/6), and genes involved in the apoptotic pathway (Bcl-2, Bax, Cas-3) in MCF-7 and MDA-MB-231 cells treated with palbociclib were evaluated using the real-time PCR (qRT-PCR) method. Additionally, the levels of total retinoblastoma (RB) and phosphorylated retinoblastoma (pRB) proteins were analyzed using the Western blot method. CDK4/6 and pRB expression decreased in MCF-7 and MDA-MB-231 cells treated with palbociclib. Bax and Cas-3 expression increased, while Bcl-2 expression decreased. Changes in TLR expression were also observed.

We believe that palbociclib not only stops the cell cycle and induces apoptosis in breast cancer cells, but also activates the immune response via TLRs.