Table 1 Mature adipocytes vs. cancer-associated adipocytes

Definition

Adipose tissue occupies 56% of the non-lactating breast tissue and 35% of lactating breast tissue. Adipocytes that constitute breast tissue are WAT, with lipid-storage and endocrine functions.

Adipocytes at the invasive front of breast tumor exhibit a modified phenotype, a loss of lipid content, a decrease in late adipocyte differentiation markers and overexpression of inflammatory cytokines and proteases.

Location

Mature adipocytes encapsulate around the mammary gland;

Adipocytes are separated with epithelial cells by the basement membrane.

Locate at the invasive front of breast tumor;

Adjacent to BC cells.

Morphology

Normal cell size;

Round shape;

Large unilocular lipid droplets.

Smaller cell size;

Irregular shape with smaller size;

Smaller and dispersed lipid droplets.

Function

Maintain normal breast morphology;

With endocrine functions and maintain the energy balance;

Normally expression of adipokines, including leptin, adiponectin, IL-6, CCL2, CCL5 and other cytokines.

Aberrantly expressional secretion of adipokines, including leptin, adiponectin, IL-6, CCL2, CCL5 and other cytokines.

Impact on breast cancer

The promoting effect of adipocytes on BC is far less compared with CAAs;

The risk of BC might increase under the condition of obesity.

The interaction between CAAs and BC cells may directly affect their morphology and function;

CAAs could promote BC cell proliferation, viability, migration and invasion in vitro, and could enhance tumor growth and metastasis in vivo xenograft studies in a paracrine manner.