Overview on Epigenetic Re-programming: A Potential Therapeutic Intervention in Triple Negative Breast Cancers

Document Type: Systematic Review and Meta-analysis

Authors

UKM Medical Molecular Biology Institute (UMBI), University Kebangsaan Malaysia Medical Centre, Jalan Yaccob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur, Malaysia.

Abstract

Breast cancer treatments leads to variable responses. Hormonal therapy is beneficial to receptor positive breast cancer
subtypes and display better clinical outcome than triple negative breast cancers (TNBCs) with FEC (5-Fluorouracil,
Epirubicin and Cyclophosphamide) the mainstay chemotherapy regiment. Owning to their negative expressions of
estrogen (ER), progesterone (PR) and HER2 receptors, disease recurrence and metastasis befalls some patients indicating
resistance to FEC. Involvement of epigenetic silencing through DNA methylation, histone methylation, acetylation and
sumoylation may be the key player in FEC chemoresistance. Epigenetic and molecular profiling successfully classified
breast cancer subtypes, indicating potential driver mechanisms to the progression of TNBCs but functional mechanisms
behind chemoresistance of these molecular markers are not well defined. Several epigenetic inhibitors and drugs have
been used in the management of cancers but these attempts are mainly beneficial in hematopoietic cancers and not
specifically favourable in solid tumours. Hypothetically, upon administration of epigenetic drugs, recovery of tumour
suppressor genes is expected. However, high tendency of switching on global metastatic genes is predicted. Polycomb
repressive complex (PRC) such as EZH2, SETD1A, DNMT, is known to have repressive effects in gene regulation and
shown to inhibit cell proliferation and invasion in breast cancers. Individual epigenetic regulators may be an option
to improve chemo-drug delivery in cancers. This review discussed on molecular signatures of various breast cancer
subtypes and on-going attempts in understanding underlying molecular mechanisms of epigenetic regulators as well
as providing insights on possible ways to utilize epigenetic enzymes/inhibitors with responses to chemotherapeutic
drugs to re-program cellular and biological outcome in TNBCs.

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