Emerging Role of Epigenetic Modifiers in Breast Cancer Pathogenesis and Therapeutic Response

ACSL4-mediated H3K9 and H3K27 hyperacetylation upregulates SNAIL to drive TNBC metastasis

Triple-negative breast cancer (TNBC) has profound unmet medical need globally for its devastating clinical outcome associated with rapid metastasis and lack of targeted therapies. Recently, lipid metabolic reprogramming especially fatty acid oxidation (FAO) has emerged as a major driver of breast cancer metastasis. Analyzing the expression of major FAO regulatory genes in breast cancer, we found selective overexpression of acyl-CoA synthetase 4 (ACSL4) in TNBC, which is primarily attributed to the absence of progesterone receptor. Loss of ACSL4 function, by genetic ablation or pharmacological inhibition significantly reduces metastatic potential of TNBC. Global transcriptome analysis reveals that ACSL4 activity positively influences the gene expression related to TNBC migration and invasion. Mechanistically, ACSL4 modulates FAO and intracellular acetyl-CoA levels, leading to hyperacetylation of particularly H3K9ac and H3K27ac marks resulting in overexpression of SNAIL during the course of TNBC metastatic spread to lymph node and lung. Further, human TNBC metastasis exhibits positive correlation among ACSL4, H3K9ac, H3K27ac, and SNAIL expression. Altogether, our findings provide molecular insights regarding the intricate interplay between metabolic alterations and epigenetic modifications, intertwined to orchestrate TNBC metastasis, and posit a rational understanding for the development of ACSL4 inhibitors as a targeted therapy against TNBC.

Dissecting the epigenetic orchestra of HDAC isoforms in breast cancer development: a review

Epigenetic modulators have recently emerged as potential targets in cancer therapy. Breast cancer, the second leading cause of cancer-related deaths among women globally and the most common cancer in India, continues to have a low survival rate despite available treatments. This underscores the urgent need for more effective therapeutic strategies. Histone deacetylases (HDACs), a prominent class of epigenetic modulators, are frequently overexpressed in various cancers, including breast cancer, making them and their downstream pathways, a focus of current research, aiming to develop more effective and less invasive treatments that could help overcome chemoresistance and enhance patient outcomes. Despite the growing body of evidences, a comprehensive and consolidated review on molecular intricacy behind the HDAC-mediated epigenetic regulation of breast cancer is conspicuously absent. Therefore, this review aims to open doors for future research by exploring the evolving role of HDACs, their molecular mechanisms, and their potential as therapeutic targets in breast cancer treatment.

Epigenetic deregulation in breast cancer microenvironment: Implications for tumor progression and therapeutic strategies

Breast cancer comprises a substantial proportion of cancer diagnoses in women and is a primary cause of cancer-related mortality. While hormone-responsive cases generally have a favorable prognosis, the aggressive nature of triple-negative breast cancer presents challenges, with intrinsic resistance to established treatments being a persistent issue. The complexity intensifies with the emergence of acquired resistance, further complicating the management of breast cancer. Epigenetic changes, encompassing DNA methylation, histone and RNA modifications, and non-coding RNAs, are acknowledged as crucial contributors to the heterogeneity of breast cancer. The unique epigenetic landscape harbored by each cellular component within the tumor microenvironment (TME) adds great diversity to the intricate regulations which influence therapeutic responses. The TME, a sophisticated ecosystem of cellular and non-cellular elements interacting with tumor cells, establishes an immunosuppressive microenvironment and fuels processes such as tumor growth, angiogenesis, and extracellular matrix remodeling. These factors contribute to challenging conditions in cancer treatment by fostering a hypoxic environment, inducing metabolic stress, and creating physical barriers to drug delivery. This article delves into the complex connections between breast cancer treatment response, underlying epigenetic changes, and vital interactions within the TME. To restore sensitivity to treatment, it emphasizes the need for combination therapies considering epigenetic changes specific to individual members of the TME. Recognizing the pivotal role of epigenetics in drug resistance and comprehending the specificities of breast TME is essential for devising more effective therapeutic strategies. The development of reliable biomarkers for patient stratification will facilitate tailored and precise treatment approaches.

Beyond genetics: Exploring the role of epigenetic alterations in breast cancer

Breast cancer remains a major global health challenge. Its rising incidence is attributed to factors such as delayed diagnosis, the complexity of its subtypes, and increasing drug resistance, all contributing to less-than-ideal patient outcomes. Central to the progression of breast cancer are epigenetic aberrations, which significantly contribute to drug resistance and the emergence of cancer stem cell traits. These include alterations in DNA methylation, histone modifications, and the expression of non-coding RNAs. Understanding these epigenetic changes is crucial for developing advanced breast cancer management strategies despite their complexity. Investigating these epigenetic modifications offers the potential for novel diagnostic markers, more accurate prognostic indicators, and the identification of reliable predictors of treatment response. This could lead to the development of new targeted therapies. However, this requires sustained, focused research efforts to navigate the challenges of understanding breast cancer carcinogenesis and its epigenetic underpinnings. A deeper understanding of epigenetic mechanisms in breast cancer can revolutionize personalized medicine. This could lead to significant improvements in patient care, including early detection, precise disease stratification, and more effective treatment options.

Advances in Epigenetic Therapeutics for Breast Cancer

The epigenetic deregulations correlate with tumorigenesis, resistance to therapy, and metastasis of breast cancer cells. Given the predominance of aberrant epigenomic mechanisms, there is a growing emphasis on targeting epigenetic mechanisms for breast cancer therapeutic development. Selective inhibitors of epigenetic enzymes and the combined approach of epigenetic therapies with chemotherapies or hormone therapies in the treatment of breast cancer represent promising therapeutic strategies. In this chapter, we review the targeting of epigenetic mechanisms and highlight current epigenetic research in the development of breast cancer therapy.