Human-specific RNA analysis shows uncoupled epithelial-mesenchymal plasticity in circulating and disseminated tumour cells from human breast cancer xenografts

• Published in: Clinical & experimental metastasis Vol. 36; no. 4; pp. 393 - 409
• Main Authors: Tachtsidis, Anthony, Le, Anh Viet-Phuong, Blick, Tony, Gunasinghe, Devika, De Sousa, Emma, Waltham, Mark, Dobrovic, Alex, Thompson, Erik W.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-08-2019; Springer Nature B.V
• Subjects: Animals; Biomedical and Life Sciences; Biomedicine; Blood circulation; BNIP3 protein; Bone cancer; Bone marrow; Bone tumors; Breast cancer; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Cancer Research; Cell Line, Tumor; E-cadherin; Epidermal growth factor receptors; Epithelial-Mesenchymal Transition; Female; Hematology; Heterogeneity; Humans; Hypoxia; ILK protein; Markers; Mesenchyme; Metabolism; Metastases; Mice, SCID; Neoplasm Micrometastasis; Neoplasm Transplantation; Neoplasm, Residual; Neoplastic Cells, Circulating - pathology; Notch1 protein; Oncology; Phenotypes; Phenotypic plasticity; Plastic properties; Plasticity; Research Paper; Ribonucleic acid; RNA; RNA, Messenger - analysis; Snail protein; Stem cells; Surgical Oncology; Transplantation, Heterologous; Tumors; Xenografts; Xenotransplantation; Circulating tumour cell (CTC); Epithelial-mesenchymal transition (EMT); Mesenchymal-epithelial transition (MET); Disseminated tumour cell (DTC); Epithelial-mesenchymal plasticity (EMP); Breast cancer (BC)
• ISSN: 0262-0898; 1573-7276
• DOI: 10.1007/s10585-019-09977-y

Blood samples, bone marrow, tumours and metastases where possible were collected from SCID mice bearing orthotopic xenografts of the triple-negative MDA-MB-468 cell line or a transplantable ER-positive patient derived xenograft (ED-03), and assessed using human-specific, tandem-nested RT-qPCR for markers relating to detection of circulating (CTCs) and disseminated tumour cells (DTCs), breast cancer clinicopathology, the ‘cancer stem cell’ phenotype, metabolism, hypoxia and epithelial-mesenchymal plasticity (EMP). Increased levels of
SNAI1
,
ILK
,
NOTCH1
,
CK20
, and
PGR
, and a decrease/loss of
EPCAM
in CTCs/DTCs were observed relative to the primary xenograft across both models. Decreased
CD24
and
EGFR
was restricted to the MDA-MB-468 model, while increased
TFF1
was seen in the ED-03 model. The major metabolic regulator
PPARGC1A
, and several hypoxia-related markers (
HIF1A
,
APLN
and
BNIP3
) were significantly elevated in both models. Increased expression of mesenchymal markers including
SNAI1
was seen across both models, however
CDH1
did not decrease concordantly, and several other epithelial markers were increased, suggesting an uncoupling of EMP to produce an EMP hybrid or partial-EMT. Single cell analysis of ED-03 CTCs, although limited, indicated uncoupling of the EMP axis in single hybrid cells, rather than distinct pools of epithelial or mesenchymal-enriched cells, however dynamic heterogeneity between CTCs/DTCs cannot be ruled out. Reduced
CD24
expression was observed in the MDA-MB-468 CTCs, consistent with the ‘breast cancer stem cell’ phenotype, and metastatic deposits in this model mostly resembled the primary xenografts, consistent with the mesenchymal-epithelial transition paradigm.