TABLE 1.
Molecular profile of brain metastasis‐initiating circulating tumor cells
| Molecule | Finding Description | Reference |
|---|---|---|
| EpCAM | Absence of EpCAM expression in CTCs derived from BMBC | Zhang et al 16 |
| HER2 | Identified in a subset of CTCs harboring high competence for brain metastasis. CTCs derived from triple‐negative BMBC patient express HER2 | Zhang et al 16 and Wu et al 18 |
| EGFR | Identified in a subset of CTCs harboring high competence for brain metastasis. CTC derived from triple‐negative BMBC patient express EGFR | Zhang et al 16 |
| HPSE | Identified in a subset of CTCs harboring high competence for brain metastasis | Zhang et al 16 |
| Notch1 | Identified in a subset of CTCs harboring high competence for brain metastasis. Notch activity is a feature of BMBC CTCs | Zhang et al 16 and Boral et al 17 |
| Notch3 | Copy number alteration (gain) detected in CTC lines derived from BMBC | Riebensahm et al 22 |
| uPAR/integrin β1 | EpCAM‐negative CTCs expressing uPAR/intB1 were detected in the blood of patients whose breast cancer had metastasized to the brain | Vishnoi et al 67 |
| MUC1 | Copy number alteration (gain 1q22‐q23.2) detected in CTC lines derived from BMBC | Riebensahm et al 22 |
| PDPK1 | Copy number alteration (gain) detected in CTC lines derived from BMBC | Riebensahm et al 22 |
| TP53, ARID1A, CDH1, TTN | Most frequently mutated genes in CTC lines derived from BMBC | Riebensahm et al 22 |
| Nuclear DUSP6 | DUSP6 protein is predominantly nuclear in HER2‐positive CTCs and brain metastases of TNBC patients | Wu et al 18 |
| miR‐210 | Upregulated miRNA in exosomes from BM vs non‐BM CTC line | Camacho et al 21 |
| miR‐19a, miR‐29c | Downregulated miRNA in exosomes from BM vs non‐BM CTC line | Camacho et al 21 |
| phospho‐p70 S6 Kinase‐Thr389, annexin VII, phosphor‐PDK1‐Ser241, Chk1, Smad3 | Upregulated proteins in exosomes from BM vs non‐BM CTC line | Camacho et al 21 |
| ACC1, TFRC, TSC1, Bcl‐xL | Downregulated proteins in exosomes from BM vs non‐BM CTC line | Camacho et al 21 |
| Cathepsin S | CTSS was highly expressed in SCLC CTC lines | Rath et al 19 |
| Semaphorin 4D | SEMA4D promotes brain metastasis by enabling breast cancer CTC lines to cross the blood–brain barrier | Klotz et al 20 |
| MYC, GPX1 | MYC upregulates the antioxidant enzyme GPX1 expression in breast cancer CTCs. MYC/GPX1 mitigate the oxidative stress elicited by activated microglia | Klotz et al 20 |
Abbreviations: BM, brain metastatic; BMBC, brain metastatic breast cancer; CTC, circulating tumor cell; EpCAM, epithelial cell adhesion molecule; SCLC, small cell lung cancer; TNBC, triple‐negative breast cancer.