Foxy-5

BACKGROUND: ;Oral squamous cell carcinoma (OSCC) constitutes 90% of all cancers in the oral cavity, and the prognosis for patients diagnosed with OSCC is still poor. The identification of novel therapeutic targets and prognostic markers for OSCC is therefore essential. Previous studies of OSCC revealed an increased expression of WNT5A in the tumor tissue. However, no functional studies of WNT5A-induced effects in OSCC have been performed.;METHODS: ;Two different OSCC cell lines were used for analysis of WNT5A expression by Western blot, whereas WNT5A-induced responses were analyzed by measuring calcium (Ca²⁺) signaling, PKC activation, migration and invasion.;RESULTS: ;Despite the lack of WNT5A expression, both cell lines responded to recombinant WNT5A (rWNT5A) with activation of the non-canonical WNT/Ca²⁺ /PKC pathway. This effect was ascertained to be mediated by WNT5A by use of the WNT5A antagonist, Box5. To investigate how WNT5A affects tumor progression, rWNT5A-induced alterations in BrdU absorbance (reflecting the number of tumor cells) were analyzed. rWNT5A had no effect on BrdU absorbance but instead promoted tumor cell migration and invasion. These results were confirmed by the use of the WNT5A-mimicking peptide Foxy5, while the rWNT5A-induced migration was blocked by secreted Frizzled-related protein 1 (SFRP1), protein kinase C inhibitors or the intracellular Ca²⁺ chelator, MAPT.

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.

One third of all breast cancers are estrogen receptor alpha (ERalpha) negative, carry a poor overall prognosis, and do not respond well to currently available endocrine therapies. New treatment strategies are therefore required. Loss of Wnt-5a has previously been correlated with loss of ERalpha in clinical breast cancer samples, and we sought to investigate this association further. Three breast cancer cell lines (MDA-MB-231, MDA-MB-468, and 4T1) lacking expression of ERalpha and Wnt-5a, and one breast cancer cell line (T47D) expressing both proteins were used in this study. Wnt-5a signaling was generated in ERalpha-negative cell lines via stimulation with either recombinant Wnt-5a protein or a Wnt-5a-derived hexapeptide (Foxy-5) possessing Wnt-5a signaling properties. ERalpha expression was restored at both mRNA and protein level, after treatment with recombinant Wnt-5a or Foxy-5. This restoration of expression occurred in parallel with a reduction in methylation of the ERalpha promoter. Up-regulated ERalpha could be activated, initiate transcription of progesterone receptor and pS2, and activate an estrogen response element reporter construct. Significantly, breast cancer cells re-expressing ERalpha responded to treatment with the selective estrogen receptor modulator tamoxifen, as measured by induction of apoptosis and cell growth inhibition.