Vorinostat induces G2/M cell cycle arrest in breast cancer cells via upregulation of PTEN.

Objective: Breast cancer (BC) is the most common type of cancer in females worldwide. Various approaches were proposed to treat the disease, with no sole agent proved efficient. Thus, understanding the molecular mechanisms of different drugs became mandatory. The present study aimed at evaluating the role of erlotinib (ERL) and vorinostat (SAHA) in inducing apoptosis in breast cancer cells. The role of these drugs was assessed also on the expression profile of some cancer-related genes; PTEN, P21, TGF, and CDH1.

Materials And Methods: In the present study, breast cancer cells (MCF-7) and MDA-MB-231 along with human amniotic cells (WISH) were treated with two concentrations (50, and 100 µM) of erlotinib (ERL) and vorinostat (as known as SAHA) for 24 h. Cells were harvested for downstream analysis. DNA content and apoptosis were analyzed by flow cytometer, and qPCR was performed to assess the expression of different cancer-related genes.

Results: The results indicated that ERL and SAHA arrested both breast cancer cells at the G2/M phase after 24 h compared to normal cells and control. For apoptosis, BC cells showed an elevated level of total apoptosis (early and late) increasing the concentrations of the two applied drugs, with the most effective concentration of ERL at 100 µM in the 24-h treatment. In the control cells, SAHA was proved to be the most effective drug at a concentration of 100 µM with a percentage of apoptosis ranging from 1.7-12% in the 24-h treatment. Necrosis also was dose-dependent in the two breast cancer cell lines used. We further evaluated the expression profiles of PTEN, P21, TGF-β, and CDH1. In MCF-7, data indicated that for TGF-β, PTEN, and P21, the most effective treatment was SAHA at a concentration of 100 µM, while for CDH1, the most effective concentration was ERL at 100 µM. A similar profile was observed in MDA-MB-232, where for TGF-β, PTEN, and P21, the most effective treatment was SAHA at a concentration of 100 µM, while for CDH1, the most effective concentration was SAHA at 50 µM.

Conclusions: Our results shed some light on the role of ERL and SAHA in regulating the expression of cancer-related genes, though these data need further investigation.