Targeted Destruction of S100A4 Inhibits Metastasis of Triple Negative Breast Cancer Cells

• Published in: Biomolecules 2023, Vol.13 (7)
• Main Authors: Ismail, Thamir M, Crick, Rachel G, Du, Min, Shivkumar, Uma, Carnell, Andrew, Barraclough, Roger, Wang, Guozheng, Cheng, Zhenxing, Yu, Weiping, Platt-Higgins, Angela, Nixon, Gemma, Rudland, Philip S
• Format: Report
• Language: English
• Subjects: Calcium-binding proteins; Drug targeting; Health aspects; Metastasis; Methods; Prevention; Risk factors
• ISSN: 2218-273X; 2218-273X
• DOI: 10.3390/biom13071099

Most patients who die of cancer do so from its metastasis to other organs. The calcium-binding protein S100A4 can induce cell migration/invasion and metastasis in experimental animals and is overexpressed in most human metastatic cancers. Here, we report that a novel inhibitor of S100A4 can specifically block its increase in cell migration in rat (IC[sub.50] , 46 µM) and human (56 µM) triple negative breast cancer (TNBC) cells without affecting Western-blotted levels of S100A4. The moderately-weak S100A4-inhibitory compound, US-10113 has been chemically attached to thalidomide to stimulate the proteasomal machinery of a cell. This proteolysis targeting chimera (PROTAC) RGC specifically eliminates S100A4 in the rat (IC[sub.50] , 8 nM) and human TNBC (IC[sub.50] , 3.2 nM) cell lines with a near 20,000-fold increase in efficiency over US-10113 at inhibiting cell migration (IC[sub.50] , 1.6 nM and 3.5 nM, respectively). Knockdown of S100A4 in human TNBC cells abolishes this effect. When PROTAC RGC is injected with mouse TNBC cells into syngeneic Balb/c mice, the incidence of experimental lung metastases or local primary tumour invasion and spontaneous lung metastasis is reduced in the 10–100 nM concentration range (Fisher’s Exact test, p ≤ 0.024). In conclusion, we have established proof of principle that destructive targeting of S100A4 provides the first realistic chemotherapeutic approach to selectively inhibiting metastasis.