Correlation between SFRP1 expression and clinicopathological parameters in patients with triple-negative breast cancer.

Aim: Breast cancer is a heterogeneous disease with distinct molecular and clinical behavior demanding reliable biomarkers, especially in triple-negative breast cancer (TNBC). This study seeks to improve the understanding of SFRP1 as a potential biomarker in breast cancer focusing on TNBC. Materials & methods: SFRP1 expression was investigated via immunohistochemistry with two anti-SFRP1-antibodies on tissue-microarrays of 376 invasive breast cancers. Results: Statistical analysis revealed a highly significant association between TNBC (n = 36) and SFRP1 expression (p < 0.001). SFRP1 expression was significantly associated with younger age, higher tumor stage, size and grade. Conclusion: SFRP1 expression is strongly correlated with TNBC on protein level. Associations with age and tumor grade support the role of SFRP1 as a biomarker for chemotherapy response in TNBC.

The anti-androgen drug dutasteride renders triple negative breast cancer cells more sensitive to chemotherapy via inhibition of HIF-1α-/VEGF-signaling.

BACKGROUND: Triple negative breast cancer (TNBC) is characterized by lack of expression of both estrogen and progesterone receptor as well as lack of amplification of HER2. Patients with TNBC carry an unfavorable prognosis compared to other breast cancer subtypes given that endocrine or HER2 targeted therapies are not effective, rendering chemotherapy the sole effective treatment option to date. Therefore, there is a high demand for additional novel treatment options. FINDINGS: We previously published a list of genes showing both higher gene expression rates in TNBC and, in addition, are known to encode targets of non-oncologic drugs. SRD5A1, which encodes the type-1 isoform of the steroid-5alpha-reductase, which is involved in androgen metabolism, was found to be one of these genes. Dutasteride is a dual blocker of both the type-1 and type-2 isoform of SRD5A1 and is indicated in the treatment of benign prostate hyperplasia. Treatment of TNBC cell lines with dutasteride was associated with a dose-dependent decrease in cell viability, altered protein expression of VEGF and HIF-1α and increased chemosensitivity. CONCLUSION: Our results demonstrate that the SRD5A1-corresponding anti-androgenic drug dutasteride might act as a combinatorial therapeutic option besides standard chemotherapy in highly aggressive TNBC.

Influence of secreted frizzled receptor protein 1 (SFRP1) on neoadjuvant chemotherapy in triple negative breast cancer does not rely on WNT signaling.

BACKGROUND: Triple negative breast cancer (TNBC) is characterized by lack of expression of both estrogen and progesterone receptor as well as lack of overexpression or amplification of HER2. Despite an increased probability of response to chemotherapy, many patients resistant to current chemotherapy regimens suffer from a worse prognosis compared to other breast cancer subtypes. However, molecular determinants of response to chemotherapy specific to TNBC remain largely unknown. Thus, there is a high demand for biomarkers potentially stratifying triple negative breast cancer patients for neoadjuvant chemotherapies or alternative therapies. METHODS: In order to identify genes correlating with both the triple negative breast cancer subtype as well as response to neoadjuvant chemotherapy we employed publicly available gene expression profiles of patients, which had received neoadjuvant chemotherapy. Analysis of tissue microarrays as well as breast cancer cell lines revealed correlation to the triple negative breast cancer subtype. Subsequently, effects of siRNA-mediated knockdown on response to standard chemotherapeutic agents as well as radiation therapy were analyzed. Additionally, we evaluated the molecular mechanisms by which SFRP1 alters the carcinogenic properties of breast cancer cells. RESULTS: SFRP1 was identified as being significantly overexpressed in TNBC compared to other breast cancer subtypes. Additionally, SFRP1 expression is significantly correlated with an increased probability of positive response to neoadjuvant chemotherapy. Knockdown of SFRP1 in triple negative breast cancer cells renders the cells more resistant to standard chemotherapy. Moreover, tumorigenic properties of the cells are modified by knockdown, as shown by both migration or invasion capacity as well reduced apoptotic events. Surprisingly, we found that these effects do not rely on Wnt signaling. Furthermore, we show that pro-apoptotic as well as migratory pathways are differentially regulated after SFRP1 knockdown. CONCLUSION: We could firstly show that SFRP1 strongly correlates with the triple negative breast cancer subtype and secondly, that SFRP1 might be used as a marker stratifying patients to positively respond to neoadjuvant chemotherapy. The mechanisms by which tumor suppressor SFRP1 influences carcinogenic properties of cancer cells do not rely on Wnt signaling, thereby demonstrating the complexity of tumor associated signaling pathways.

HS3ST2 modulates breast cancer cell invasiveness via MAP kinase- and Tcf4 (Tcf7l2)-dependent regulation of protease and cadherin expression.

Heparan sulfate 3-O-sulfotransferase 2 (HS3ST2), an enzyme mediating 3-O-sulfation of heparan sulfate (HS), is silenced by hypermethylation in breast cancer. As HS has an important co-receptor function for numerous signal transduction pathways, the phenotypical changes due to HS3ST2 reexpression were investigated in vitro using high and low invasive breast cancer cell lines. Compared to controls, highly invasive HS3ST2-expressing MDA-MB-231 cells showed enhanced Matrigel invasiveness, transendothelial migration and motility. Affymetrix screening and confirmatory real-time PCR and Western blotting analysis revealed increased expression of several matrix metalloproteinases, cadherin-11, E-cadherin and CEACAM-1, while protease inhibitor and annexin A10 expression were decreased. Low invasive HS3ST2 -expressing MCF-7 cells became even less invasive, with no change in gelatinolytic MMP activity. HS3ST2 expression increased HS-dependent basal and FGF2-specific signaling through the constitutively active p44/42 MAPK pathway in MDA-MB-231 cells. Increased MAPK activation was accompanied by upregulation of ß-catenin in MDA-MB-231, and of the transcription factor Tcf4 in both cell lines. Dysregulation of Tcf4-regulated ion transporters and increased cytosolic acidification were observed in HS3ST2-expressing MDA-MB-231 cells, which is a possible underlying cause of increased chemosensitivity towards doxorubicine and paclitaxel in these cells. This study provides the first in vitro evidence of the involvement of HS3ST2 in breast cancer cell invasion and chemosensitivity.