The hypomethylating agent azacytidine is effective in the treatment of brain metastasized triple negative breast cancer cells
Authors: Liu Tuoen , Butler Christopher , Hatcher Shea , Tyree Evan , Yost Michael , Lockman Paul 
Published: June 2021

Breast cancer patients with brain metastasis have a poor prognosis, with a median survival time less than 1 year despite treatment. Current chemotherapeutic agents are largely ineffective against brain metastases of breast cancer. DNA hypermethylation can lead to suppression of tumor‐suppression genes which contributes to the cancer progression. DNA hypomethylating agents can activate tumor suppressor genes which are silenced by hypermethylation in breast cancer. Thus, we hypothesize that hypomethylating drugs may be emerging as novel chemotherapy drugs in the treatment of brain metastasis breast cancer.

We utilized two breast cancer cell lines in our study: the regular triple negative breast cancer cells (“MDA‐MB‐231” cells) and brain metastasized triple negative breast cancer cells (referred as “MDA‐MB‐231 Br” cells). We treated both cell lines with various concentrations (0–100 mM) of the hypomethylating agent azacytidine (abbreviated as “AZA”). The anti‐tumor effects of the drug were studied by measuring cell proliferation, apoptosis, signaling transduction, angiogenesis, and metastasis.

We first found that the brain metastasized cancer cells (MDA‐MB‐231 Br) have different oncological phenotype compared to the regular cancer cells (MDA‐MB‐231): (1) MDA‐MB‐231 Br cells primarily reside in brain, while MDA‐MB‐231 cells migrate to other tissues in vivo. (2) MDA‐MB‐231 Br cells grow much faster compared to MDA‐MB‐231 cells in vitro. (3) MDA‐MB‐231 Br cells have higher metastasis potential compared to MDA‐MB‐231 cells.

Furthermore, we found that the MDA‐MB‐231 Br cells are more sensitive to AZA treatment compared to MDA‐MB‐231 cells: (1) IC50 value of AZA in MDA‐MB‐231 Br cells is significantly lower than that in MDA‐MB‐231 cells (48 ± 4.90 mM vs. 83.33 ± 8.82 mM, p<0.01). (2) AZA treatment triggers higher percentage of cell apoptosis in MDA‐MB‐231 Br cells. (3) AZA treatment inhibits the Wnt signal transduction pathway in MDA‐MB‐231 Br cells. (4) AZA treatment inhibits angiogenesis in MDA‐MB‐231 Br cells by inhibiting the expression of VEGF receptor.

In conclusion, we tested the effectiveness of the hypomethylating drug AZA in the treatment of brain metastasis triple negative breast cancer by using in vitro cell model. We found that the brain metastasized breast cancer cells have different oncological phenotype and higher metastasis potential compared to regular breast cancer cells. On our preliminary results suggest that the hypomethylating drug AZA is effective in treating brain metastasized breast cancer cells. Currently, we are comparing the DNA methylation of the genes with important function in tumor metastasis between these two cell lines. The on‐going study is useful in elucidating the molecular mechanism of hypomethylating drugs in brain metastasis breast cancer treatment.

Support or Funding Information

This study is funded by the West Virginia Clinical and Translational Science Institute (WVCTSI) pilot grant (Drs. Lockman and Liu).

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.