The WNT-5a derived peptide, Foxy-5, possesses dual properties that impair progression of ERalpha negative breast cancer.

Despite improvements in detection and treatment, breast cancer remains the most common female cancer worldwide, and metastatic associated mortality is a significant public health issue. Patients with tumors negative for estrogen receptor (ERalpha), have a particularly poor prognosis, partly due to their inability to respond to current endocrine treaments. Expression of Wnt-5a has been associated with prolonged recurrence free survivial in clinical material, and Wnt-5a also inhibits migration and invasion of breast cancer cell lines. Loss of Wnt-5a is associated with loss of ERalpha in clinical breast cancer material, and Wnt-5a signaling upregulates ERalpha in ERalpha negative breast cancer cell lines. A Wnt-5a derived hexapeptide, Foxy-5, has been developed and like Wnt-5a, increases adhesion and inhibits migration of breast cancer cells. Furthermore, Foxy-5 significantly reduced liver and lung metastases in a murine ERalpha negative breast cancer model. Foxy-5 also upregulated ERalpha in this in vivo model and most significantly, in vitro rendered cells responsive to the selective estrogen receptor modulator, Tamoxifen. Together these studies suggest that Foxy-5 may be a potential new supplementary treatment for ERalpha negative breast cancer patients, as it addresses two of the most important aspects of cancer related mortality -- non response to endocrine therapy and metastasis.