Fatty acid synthase: a druggable driver of breast cancer brain metastasis

ABSTRACT

Introduction

Brain metastasis (BrM) is a key contributor to morbidity and mortality in breast cancer patients, especially among high-risk epidermal growth factor receptor 2-positive (HER2+) and triple-negative/basal-like molecular subtypes. Optimal management of BrM is focused on characterizing a ‘BrM dependency map’ to prioritize targetable therapeutic vulnerabilities.

Areas covered

We review recent studies addressing the targeting of BrM in the lipid-deprived brain environment, which selects for brain-tropic breast cancer cells capable of cell-autonomously generating fatty acids by upregulating de novo lipogenesis via fatty acid synthase (FASN). Disruption of FASN activity impairs breast cancer growth in the brain, but not extracranially, and mapping of the molecular causes of organ-specific patterns of metastasis has uncovered an enrichment of lipid metabolism signatures in brain metastasizing cells. Targeting SREBP1–the master regulator of lipogenic gene transcription–curtails the ability of breast cancer cells to survive in the brain microenvironment.

Expert opinion

Targeting FASN represents a new therapeutic opportunity for patients with breast cancer and BrM. Delivery of brain-permeable FASN inhibitors and identifying strategies to target metabolic plasticity that might compensate for impaired brain FASN activity are two potential roadblocks that may hinder FASN-centered strategies against BrM.

KEYWORDS:

• Fatty acid synthase
• HER2
• SREBP
• breast cancer
• lipogenesis
• metabolism
• brain metastasis

Article highlights

• The lipid-poor brain environment selects for breast cancer cells that are capable of cell-autonomously synthesizing fatty acids.

• Upregulation of de novo lipid biosynthesis via fatty acid synthase (FASN) enables breast cancer cells to form metastatic brain lesions.

• Targeted disruption of the lipogenic program prevents breast cancer cells from surviving in the brain microenvironment.

• Chemical inhibition of FASN activity specifically impairs breast cancer growth in the brain, but not extracranially.

• Brain-permeable versions of clinical-grade FASN inhibitors could represent a new therapeutic opportunity for the treatment and secondary prevention of breast cancer brain metastasis.

• Metabolic plasticity that compensates for impaired endogenous lipogenic activity in the brain could be circumvented by next-generation FASN inhibitors.

This box summarizes key points contained in the article.

Acknowledgments

The authors would like to thank Kenneth McCreath for editorial support. The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Defense, the United States government, or the National Institutes of Health.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This work was supported by the NIH National Cancer Institute Grant R01 CA116623 (to Ruth Lupu) and by the U.S. Department of Defense (DOD)-Breakthrough 3 Grants BC151072 and BC151072P1 (to Ruth Lupu). Work in the Menendez laboratory is supported by the Spanish Ministry of Science and Innovation (Grant PID2019-104055GB-I00, Plan Nacional de I+D+I, founded by the European Regional Development Fund, Spain) and by an unrestricted research grant from the Fundació Oncolliga Girona (Lliga catalana d’ajuda al malalt de càncer, Girona).