This document discusses epithelial-mesenchymal transition (EMT) and its role in cancer metastasis. It summarizes findings from a study using a triple-transgenic mouse model of breast cancer metastasis that found: 1) Primary tumor cells disseminated and formed metastases while maintaining their epithelial phenotype, not undergoing EMT. 2) Inhibiting EMT with miR-200 had no effect on metastasis. 3) Non-EMT tumor cells were sensitive to chemotherapy, whereas mesenchymal cells were resistant. The study provides evidence that EMT may not be required for cancer metastasis in this model.

1. S
Epithelial-mesenchymal transition
Kamil Grzyb
PhD student at ICS
LCSB

2. What is EMT (or MET)

3. Where EMT is present
S EMTs are associated with
S embryo implantation,
S embryogenesis,
S organ development,
S wound healing
S But also contributes pathologically to fibrosis or cancer
metastasis

4. Cancer metastasis with EMT
Nature 493, 487–488 (24 January 2013)

5. Triple-transgenic mouse model
ü Mouse models of breast cancer metastasis (MMTV - PyMT)
ü Fsp1 is the critical gatekeeping gene of EMT initiation
ü Cre-switchable fluorescent marker under the control of the -actin
promoter (Rosa26) – irreversible!

6. Confirming the E(RFP+) and M(GFP+)
phenotype

7. Primary tumor & lung metastasis stained

8. Tumor graft for EMT
2% GFP+
98% RFP+
GFP+ EMT tumour cells
did not contribute to lung
metastasis

9. Validating EMT lineage tracing system

10. EMT lineage tracing system
Almost no
Mesenchymal
originated
metastasis

11. In vivo spreading of tri-PyMT cells.

12. Inhibit EMT with miR-200

13. M cells chemoresistance(CTX)
• Mice treated with cyclophosphamide (CTX)
• 60% tumor reduction (by êgrowth and éapoptosis)
• GFP+(mesenchymal) cell count remained static.

14. miR-200 cancel M resistance

15. RNA-sequencing

16. Summing up…
S Tumour cells disseminate and form metastases while
persisting in their epithelial phenotype.
S miR-200 (EMT inhibitor) has no effect on metastasis
S Non-EMT cells are sensitive to chemotherapy

17. Other ways that EMT possibly contribute to
cancer metastasis?

18. Tamoxifen-Cre