MGMT inhibition in ER positive breast cancer leads to CDC2, TOP2A, AURKB, CDC20, KIF20A, Cyclin A2, Cyclin B2, Cyclin D1, ERα and survivin inhibition and enhances response to temozolomide

Authors

George C. Bobustuc, Advocate Aurora HealthFollow
Amin B. Kassam, Advocate Aurora HealthFollow
Richard Rovin, Advocate Aurora HealthFollow
Sheila Jeudy
Joshua S Smith
Beth Isley
Maharaj Singh, Advocate Aurora HealthFollow
Ameya Paranjpe
Kalkunte S Srivenugopal
Santhi Konduri, Advocate Aurora HealthFollow

Recommended Citation

Bobustuc GC, Kassam AB, Rovin RA, et al. MGMT inhibition in ER positive breast cancer leads to CDC2, TOP2A, AURKB, CDC20, KIF20A, Cyclin A2, Cyclin B2, Cyclin D1, ERα and Survivin inhibition and enhances response to temozolomide. Oncotarget. 2018;9(51):29727-29742. doi: 10.18632/oncotarget.25696

Affiliations

Aurora Research Institute, Aurora Neurosciences Innovation Institute

Abstract

The DNA damage repair enzyme, O⁶-methylguanine DNA methyltransferase (MGMT) is overexpressed in breast cancer, correlating directly with estrogen receptor (ER) expression and function. In ER negative breast cancer the MGMT promoter is frequently methylated. In ER positive breast cancer MGMT is upregulated and modulates ER function. Here, we evaluate MGMT’s role in control of other clinically relevant targets involved in cell cycle regulation during breast cancer oncogenesis. We show that O⁶-benzylguanine (BG), an MGMT inhibitor decreases CDC2, CDC20, TOP2A, AURKB, KIF20A, cyclin B2, A2, D1, ERα and survivin and induces c-PARP and p21 and sensitizes ER positive breast cancer to temozolomide (TMZ). Further, siRNA inhibition of MGMT inhibits CDC2, TOP2A, AURKB, KIF20A, Cyclin B2, A2 and survivin and induces p21. Combination of BG+TMZ decreases CDC2, CDC20, TOP2A, AURKB, KIF20A, Cyclin A2, B2, D1, ERα and survivin. Temozolomide alone inhibits MGMT expression in a dose and time dependent manner and increases p21 and cytochrome c. Temozolomide inhibits transcription of TOP2A, AURKB, KIF20A and does not have any effect on CDC2 and CDC20 and induces p21. BG+/-TMZ inhibits breast cancer growth. In our orthotopic ER positive breast cancer xenografts, BG+/-TMZ decreases ki-67, CDC2, CDC20, TOP2A, AURKB and induces p21 expression. In the same model, BG+TMZ combination inhibits breast tumor growth in vivo compared to single agent (TMZ or BG) or control. Our results show that MGMT inhibition is relevant for inhibition of multiple downstream targets involved in tumorigenesis. We also show that MGMT inhibition increases ER positive breast cancer sensitivity to alkylator based chemotherapy.

Document Type

Article

PubMed ID

30038716