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Triple negative (TN) breast cancers account for about 15-20% of breast cancers and are associated with aggressiveness, poor prognosis and shorter survival. Because of the lack of specific therapy guidelines for this subgroup there is an urgent need to define specific markers for therapeutic targeting in these tumors. We observed that TN breast cancer cells lines are able to perform “Vasculogenic Mimicry” (VM) in vitro. In fact, all four TN cell lines evaluated (MDA-MB-231, MDA-MB-157, MDA-MB-468 and HCC1937) were able to form vascular channels when seeded on the murine tumor-derived basement membrane (Matrigel), whereas luminal (MCF7 and ZR-75-1) and HER2-positive (MDA-MB-361 and SKBr3) breast carcinoma cell lines did not exhibit vascular structures. Then, we evaluated the VM in xenograft tumors derived from MDA-MB-231, MCF7 and MDA-MB-361 using transmission electron microscopy (TEM). In MDA-MB-231 xenografts it has been revealed channel-like structures formed by tumor cells encompassing erytrocytes, whereas in MCF7 and MDA-MB-361 xenografts the endothelial lining delimiting blood vessels was clearly visible. Notably, blood vessels surrounded by tumor cells were also identified in human TN specimens processed for TEM, and these structures were significantly more frequent in TN compared to non-TN tumors. 60% reduction in TN vascular channel formation in vitro by an anti-bFGF monoclonal antibody together with no effect using anti-VEGF antibody indicated that TN breast carcinoma cells can generate vascular channels through bFGF-mediated pathway. Silencing different receptors involved in bFGF signal (i.e. FGFR2 and PDFGR) abrogated VM in TN cells. Treatment of MDA-MB-231 xenografts with a TKI able to block both FGFR and PDGFR induced tumor regression, versus only slight growth inhibition in tumors derived from MCF7 luminal cell line. In conclusion our findings point to the possibility that TN tumors generate vascular channels independent of tumor angiogenesis and that targeting this VM capability may represent a valid therapeutic tool. (Partially supported by AIRC). Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1598.

Background : Metaplastic carcinoma of the breast is a rare subtype of breast cancer, which is characterized by estrogen receptor/progesterone receptor and HER2 negativity. Methods : Tissue specimens from 60 metaplastic breast cancer and 60 triple-negative breast cancer patients diagnosed at a single institution between 1995 and 2009 were analyzed. Immunohistochemistry for caveolin-1 (CAV-1), vascular endothelial growth factor (VEGF), epidermal growth factor receptor (EGFR), c-kit, p53, Ki-67, breast cancer type 1 susceptibility protein (BRCA1), cytokeratin (CK)14, and CK17 were performed on both retained tissue sets. Results : Of the 60 metaplastic carcinomas, 15 tumors (25%) exhibited spindle cell component, 27 (45%) exhibited chondroid differentiation, and 18 (30%) exhibited squamous areas. Compared to triple-negative carcinomas, metaplastic carcinomas significantly more frequently expressed CK14 (p < 0.0001), CK17 (p = 0.002), EGFR (p < 0.0001), CAV-1 (p < 0.0001), and VEGF (p = 0.029). However, expressions of BRCA1, p53, c-kit, and Ki-67 were not significantly different between both groups. Conclusions : The expression profile of metaplastic carcinoma of the breast is more homogeneous than that of other triple-negative tumors and frequently over-expresses basal markers, CAV-1, and VEGF. A typical “basal-like” phenotype and frequent expressions of CAV-1 and VEGF may justify specific therapeutic approaches.

Background Currently, there is a debate as to whether triple negative breast carcinoma (TNBC) has a worse prognosis than non-TNBC. Our aim was to determine whether TNBC is a prognostic factor for survival. Methods We identified 1,048 Taiwanese breast carcinoma patients, of whom 167 (15.9%) had TNBC. Data used for analysis were derived from our cancer registry database for women with breast cancer who were diagnosed between 2002 January and 2006 December. Results In the Kaplan-Meier analysis, tumor subgroup (TNBC vs. non-TNBC) was a prognosis factor related to 5-year overall survival. In the univariate analysis, tumor subgroup (TNBC vs. non-TNBC) was a significant factor related to 5-year overall survival, in addition to age, tumor size, lymph node, metastasis, grade, stage, estrogen receptor status, progesterone receptor status, and HER2 overexpression status. In the multivariate analysis, tumor subgroup was not a significant factor related to 5-year disease-free survival (DFS). In node-positive patients, tumor subgroup was a significant factor related to 5-year overall survival, in addition to age, tumor size, metastasis, and grade. In node-negative patients, tumor subgroup was not a significant factor related to 5-year disease-free survival and 5-year overall survival. Conclusion Our results indicated that TNBC patients in Taiwan have worse 5-year overall survival than non-TNBC patients. Notably, in node-positive patients, TNBC played a prognostic role in 5-year overall survival.

Abstract #3044 Introduction: Obesity is an independent risk factor for breast cancer and obese breast cancer patients exhibit a higher risk for larger tumor burden, increased metastasis and poor response to endocrine therapy. Obesity affects breast carcinogenesis by autocrine and paracrine effects of adipocytokine leptin and IGF-1. We have previously shown that leptin induces growth stimulation of breast cancer cells by recruiting histone acetyltransferases and mediator complex to cyclin D1 promoter via activation of Stat3. In the present study, we found a novel bidirectional crosstalk between IGF-1 and leptin signaling that promotes invasion and migration of triple-negative (ER, PR, HER2 negative) breast cancer cells; MDA-MB-231, MDA-MB-468, MDA-MB-435 and HCC-1806. Methods and Results: IGF-1 induced significant tyrosine phosphorylation of leptin receptor (Ob-Rb) and leptin induced tyrosine phosphorylation of IGF-1 Receptor (IGF-1R). Combined treatment of leptin and IGF-1 induced synergistic activation of both Ob-Rb and IGF-1R along with activation of Akt and ERK. Furthermore, IGF-1 and leptin synergistically transactivated epidermal growth factor receptor (EGFR) and induced proliferation of triple negative breast cancer cells. We also found that tyrosine phosphorylation of EGFR induced by combined treatment of leptin and IGF-1 was significantly inhibited not only by EGFR tyrosine kinase inhibitor, AG1478 but also with a broad-spectrum matrix metalloproteinase inhibitor, GM6001 indicating that leptin and IGF-1 induced EGFR transactivation is dependent on proteolytic release of EGFR ligands. Intriguingly, we also found that combined treatment of leptin and IGF-1 potently induced invasion of triple negative breast cancer cells in Matrigel invasion and quantitative Electric Cell-Substrate Impedance Sensing invasion assays. Inhibition of leptin and IGF-1 mediated EGFR activation using a highly potent, reversible inhibitor of HER1/EGFR tyrosine kinase, erlotinib or dual epidermal growth factor receptor (EGFR)/human EGFR-2 (HER2) kinase inhibitor, lapatinib effectively inhibited leptin and IGF-1 induced invasion. Also, inhibition of EGFR activation using erlotinib and lapatinib reduced leptin- and IGF-1-induced migration of triple negative breast cancer cells. Discussion: Taken together these data indicate a novel bidirectional crosstalk between leptin and IGF-1 signaling that transactivates EGFR and promotes metastatic properties, invasion and migration of triple negative breast carcinoma cells. Our novel findings indicate the possibility of using EGFR inhibitors erlotinib and lapatinib to counter the pro-cancerous effects of leptin and IGF-1 signaling in triple negative breast cancers. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3044.

Introduction: Obesity is an independent risk factor for breast cancer and obese breast cancer patients exhibit a higher risk for larger tumor burden, increased metastasis, and poor response to endocrine therapy. Obesity affects breast carcinogenesis by autocrine and paracrine effects of adipocytokine leptin and IGF-1. We have previously shown that leptin induces growth stimulation of breast cancer cells by recruiting histone acetyltransferases and mediator complex to cyclin D1 promoter via activation of Stat3. In the present study, we found a novel bidirectional crosstalk between IGF-1 and leptin signaling that promotes invasion and migration of triple-negative (ER, PR, HER2 negative) breast cancer cells MDA-MB-231, MDA-MB-468, MDA-MB-435, and HCC-1806. Methods and Results: IGF-1 induced significant tyrosine phosphorylation of leptin receptor (Ob-Rb) and leptin induced tyrosine phosphorylation of IGF-1 receptor (IGF-1R). Combined treatment of leptin and IGF-1 induced synergistic activation of both Ob-Rb and IGF-1R along with activation of Akt and ERK. Furthermore, IGF-1 and leptin synergistically transactivated epidermal growth factor receptor (EGFR) and induced proliferation of triple negative breast cancer cells. We also found that tyrosine phosphorylation of EGFR induced by combined treatment of leptin and IGF-1 was significantly inhibited not only by EGFR tyrosine kinase inhibitor AG1478 but also with a broad-spectrum matrix metalloproteinase inhibitor, GM6001, indicating that leptin and IGF-1 induced EGFR transactivation is dependent on proteolytic release of EGFR ligands. Intriguingly, we also found that combined treatment of leptin and IGF-1 potently induced invasion of triple negative breast cancer cells in Matrigel invasion and quantitative Electric Cell-Substrate Impedance Sensing invasion assays. Inhibition of leptin and IGF-1 mediated EGFR activation using a highly potent, reversible inhibitor of HER1/EGFR tyrosine kinase (erlotinib) or dual EGFR/HER2 kinase inhibitor (lapatinib) effectively inhibited leptin and IGF-1 induced invasion. Also, inhibition of EGFR activation using erlotinib and lapatinib reduced leptin- and IGF-1 induced migration of triple negative breast cancer cells. Conclusions: Taken together, these data indicate a novel bidirectional crosstalk between leptin and IGF-1 signaling that transactivates EGFR and promotes metastatic properties, invasion, and migration of triple negative breast carcinoma cells. Our novel findings indicate the possibility of using EGFR inhibitors erlotinib and lapatinib to counter the pro-cancerous effects of leptin and IGF-1 signaling in triple negative breast cancers.

Context: Gene expression analysis has identified several breast cancer subtypes, including basal-like, human epidermal growth factor receptor-2 positive/estrogen receptor negative (HER2+/ER–), luminal A, and luminal B. Objectives: To determine population-based distributions and clinical associations for breast cancer subtypes. Design, Setting, and Participants: Immunohistochemical surrogates for each subtype were applied to 496 incident cases of invasive breast cancer from the Carolina Breast Cancer Study (ascertained between May 1993 and December 1996), a population based, case-control study that oversampled premenopausal and African American women. Subtype definitions were as follows: luminal A (ER+ and/or progesterone receptor positive [PR+], HER2−), luminal B (ER+ and/or PR+, HER2+), basal-like (ER−, PR−, HER2−, cytokeratin 5/6 positive, and/or HER1+), HER2+/ER− (ER−, PR−, and HER2+), and unclassified (negative for all 5 markers). Main Outcome Measures: We examined the prevalence of breast cancer subtypes within racial and menopausal subsets and determined their associations with tumor size, axillary nodal status, mitotic index, nuclear pleomorphism, combined grade, p53 mutation status, and breast cancer–specific survival. Results The basal-like breast cancer subtype was more prevalent among premenopausal African American women (39%) compared with postmenopausal African American women (14%) and non–African American women (16%) of any age (P