BECN1

BECN1 Full Name

beclin 1, autophagy related

BECN1 Introduction

Beclin 1 (BECN1), the first mammalian homolog of the yeast autophagy-related gene Atg6, is widely recognized as a central regulator of the autophagy pathway. At the molecular level, its core function is to serve as the essential scaffold protein for the class III phosphatidylinositol 3-kinase (PI3K-III/Vps34) complex. This complex catalyzes the production of phosphatidylinositol-3-phosphate (PI3P) from phosphatidylinositol. PI3P acts as a key signaling lipid during autophagosome formation and elongation, recruiting downstream autophagy-related proteins to initiate the nucleation and formation of the autophagosome. The function of BECN1 is tightly regulated by its network of interacting proteins. The most classic example is its interaction with anti-apoptotic Bcl-2 family members, such as Bcl-2 and Bcl-XL. Bcl-2 binds to the BH3 domain of BECN1 via its own BH3 domain, which prevents BECN1 from assembling with other components of the PI3K-III complex, thereby effectively inhibiting autophagy. The dissociation of this complex under cellular stress is a critical step for inducing autophagy. Furthermore, BECN1 can bind to various other proteins—including ATG14L, UVRAG, and Rubicon—forming distinct PI3K-III subcomplexes. These subcomplexes exert specific regulatory functions at different stages of autophagy or in other cellular processes, showcasing the remarkable functional versatility of BECN1 as a platform protein.

Figure 1. Model of autophagy and endocytic pathways regulated by Bcl-2–Beclin 1 and III PI3K complexes. (Source: Xu HD, et al. 2019)

The role of BECN1 in tumor development is highly complex, exhibiting a typical "double-edged sword" effect. On one hand, substantial evidence indicates that BECN1 acts as a tumor suppressor. Located in the chromosomal region 17q21, a frequent site of monoallelic deletion, BECN1 expression is often downregulated in various cancers, including breast, ovarian, and prostate cancer. Mechanistically, by promoting autophagy, BECN1 helps clear damaged organelles and misfolded proteins, maintains cellular homeostasis, and prevents genomic instability and chronic inflammation, thereby inhibiting malignant transformation. Consequently, loss or reduction of BECN1 function can impair this autophagic clearance capacity and may promote tumor initiation. On the other hand, in established tumors, BECN1-mediated autophagy can play a contrasting, pro-tumorigenic role. Tumor cells often face microenvironmental stresses such as hypoxia, nutrient deprivation, and chemotherapy. Under these conditions, autophagy is activated as a cell survival mechanism, degrading cellular components to provide energy and metabolic substrates, thereby helping tumor cells survive and promoting tumor growth, invasion, metastasis, and therapy resistance. For instance, potential pro-tumor roles of BECN1 have been observed in studies of certain non-small cell lung cancers (NSCLC). Therefore, the relationship between BECN1 expression levels and patient prognosis varies significantly depending on cancer type and stage, making it a complex yet highly potential target for cancer therapy.

Beyond its complex role in cancer, dysfunctional BECN1-mediated autophagy is also closely implicated in the pathogenesis of other major diseases. In the field of neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD), autophagic function is essential for clearing abnormally aggregated proteins within neurons, such as β-amyloid and α-synuclein. Studies have revealed significantly reduced levels of BECN1 expression in the brain tissues of AD patients. Furthermore, activation of the BECN1-dependent autophagy pathway has demonstrated notable neuroprotective effects in models of Parkinson's disease.

Alternate Names for BECN1

BECN1; beclin 1, autophagy related; ATG6; VPS30; beclin1; beclin-1; ATG6 autophagy related 6 homolog; coiled-coil myosin-like BCL2-interacting protein; beclin 1 (coiled-coil, moesin-like BCL2 interacting protein); beclin 1 (coiled-coil, moesin-like BCL2-interacting protein)

• 1. Xu HD, et al. Beclin 1, Bcl-2 and Autophagy. Adv Exp Med Biol. 2019;1206:109-126.
  2. Cao Z, et al. Beclin-1: a therapeutic target at the intersection of autophagy, immunotherapy, and cancer treatment. Front Immunol. 2024 Nov 22;15:1506426.