Table 1.
Classifications of triple negative breast cancer (TNBC).
| Subtypes | Characteristics |
|---|---|
| LEHMANN CLASSIFICATION [6] | |
| Basal-like 1 | High level of DNA repair proteins and cell-cycle regulation (high rate of tp53 mutations, amplification of MYC, CDK6, CCNE1, deletion of BRCA-2, PTEN, MDM2, RB1). |
| Basal-like 2 | Overexpression of growth factor signaling genes and overexpression of myoepithelial differentiation genes. |
| Mesenchymal like | Expression of genes associated with EMT. |
| Mesenchymal-stem like | Expression of genes associated with EMT; Enrichment in genes involved in angiogenesis, including VEGFR2 and some components of immune signaling; High expression of stem cells genes; Low expression of proliferation genes and epithelial-related genes involved in the maintenance of cellular junction, such as claudin (claudin-low breast cancer). |
| Immunomodulatory | Enrichment in genes involved in regulation of immune response, antigen processing and presentation, immune cells and cytokine signaling pathways. |
| Luminal androgen receptor (LAR) | High level of androgen receptor genes; Alterations of PI3K pathway genes (PI3KCA, AKT1, NF1, CDH1). |
| BURSTEIN CLASSIFICATION [7] | |
| Basal-like immunosuppressed (BLIS) | Downregulation of B cell, T cell, and natural killer cell immune-regulating pathways, and cytokine pathways; Expression of multiple SOX family transcription factors. |
| Basal-like immunoactivated (BLIA) | Upregulation of genes involved in immune cell function regulation; High expression of STAT genes. |
| Mesenchymal (MES) | Expression of genes involved in cell cycle, mismatch repair, and DNA damage networks, and hereditary breast cancer signaling pathways; Expression of genes normally exclusive to osteocytes (OGN) and adipocytes (ADIPOQ, PLIN1) and important growth factors (IGF1). |
| Luminal androgen receptor (LAR) | Expression of AR, ER, prolactin, and ErbB4 signaling genes. |
| MICROARRAY-BASED CLASSIFICATION [4,5] | |
| Basal-like | Low expression of luminal A signature, high proliferation score, low expression of estrogen signaling related genes (FOXA1, PGR); High expression of cell-cycle related genes (CCNE, FANCA); High expression of EMT (TWIST1, ZEB1). |
| Claudin-low | Low levels of cell adhesion proteins (Claudins 3, 4, 7, Occludin, E-caderin); Low expression of luminal genes; Inconsistent basal genes expression; Elevated expression of immune-related genes (CD4, CD79a). |
| Molecular apocrine | Activation of AR pathways. |
| Interferon-rich | Overexpression of interferon-regulated genes (STAT1, SP110). |
Epithelial-mesenchymal transition, EMT; androgen receptor, AR; estrogen receptor, ER.