A fast, precise and selective diode array HPLC method is presented for the extraction and analysis of soy isoflavonoids from foods and from human urine, plasma, and breast milk in support of mechanistic and epidemiologic studies assessing the potential cancer protective role of soya or isoflavones. Solid phase or solvent extraction was chosen for isolation, and enzymatic or acid hydrolysis procedures were used for aglycone production depending on the matrix to be analyzed. C-18 reversed-phase HPLC was applied to selectively separate and quantitate daidzein (1), glycitein (3), and genistein (4), including their malonyl (a) and acetyl (b) esters, and their mammalian metabolites equol (6) and O-desmethylangolensin (7), as well as formononetin (2), biochanin-A (5), and coumestrol (8) using a gradient elution system. UV absorbance scans and authentic standards were applied for identification purposes, additional to fluorometric monitoring, electrochemical detection, and GC/ MS analysis after trimethyl silylation. Detection limits of 20-microl injections were found to be 1.09, 0.53, 3.28, and 1.00 pmoles for daidzein, genistein, equol, and O-desmethylangolensin (DMA), respectively, by monitoring at the individual compound's absorption maximum. The proposed method was applied to monitor isoflavone levels in soy foods and in human plasma, urine and breast milk after challenge with roasted soybeans. Implications of the presented results on the potential activity of isoflavones to prevent cancer by exposing newborn infants to these agents are discussed.

The non-receptor tyrosine kinase Fer belongs to a distinct subfamily of F-BAR domain containing kinases implicated in vesicular trafficking and signaling downstream of adhesion and growth factor receptors. Targeted inactivation of the fer gene in a transgenic mouse model of HER2(+), breast cancer was associated with delayed tumor onset and reduced proliferative rates in tumor cells. Fer deficiency was associated with increased rates of epidermal growth factor (EGF)-induced epidermal growth factor receptor (EGFR) internalization and amplified Ras-Raf-Mek-Erk (Ras-MAPK) signaling in primary mammary tumor epithelial cells, as well as increased cytotoxic and anti-proliferative sensitivity to the dual EGFR/HER2 inhibitor Lapatinib (LPN). These observations suggest a model in which accelerated ligand-induced EGFR internalization in Fer-deficient cells hypersensitizes the Ras-MAPK pathway to EGF, resulting in MAPK signal amplification to levels that induce cytostasis, rather than proliferation. Thus, Ras-MAPK cytostatic signaling delays HER2 tumor initiation and increases LPN cytotoxicity in Fer-deficient model systems. Taken together, these data suggest that targeting Fer alone, or in combination with LPN, may be of therapeutic benefit in HER2(+) breast cancer.

Aberrant Ras-MAPK signaling from receptor tyrosine kinases (RTKs), including epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor-2 (HER2), is a hallmark of triple negative breast cancer (TNBC); thus providing rationale for targeting the Ras-MAPK pathway. Components of this EGFR/HER2-Ras-Raf-Mek-Erk pathway were co-targeted in the MDA-MB-231 and MDA-MB-468 human TNBC cell lines, and in vitro effects on signaling and cytotoxicity, as well as in vivo effects on xenograft tumor growth and metastasis were assessed. The dual EGFR/HER2 inhibitor lapatinib (LPN) displayed greater cytotoxic potency and MAPK signaling inhibition than the EGFR inhibitor erlotinib, suggesting both EGFR and HER2 contribute to MAPK signaling in this TNBC model. The Raf inhibitor sorafenib (SFN) or the Mek inhibitor U0126 suppressed MAPK signaling to a greater extent than LPN; which correlated with greater cytotoxic potency of SFN, but not U0126. However, U0126 potentiated the cytotoxic efficacy of LPN and SFN in an additive and synergistic manner, respectively. This in-series Raf-Mek co-targeting synergy was recapitulated in orthotopic mouse xenografts, where SFN and the Mek inhibitor selumitinib (AZD6244) inhibited primary tumor growth and pulmonary metastasis. Raf and Mek co-inhibition exhibits synergy in TNBC models and represent a promising combination therapy for this aggressive breast cancer type.

The use of celecoxib is associated with a significant decrease in breast cancer risk. However, the long-term use of high-dose celecoxib might be limited owing to cardiovascular side effects. In this study, we found that acetylbritannilactone (ABL), extract from a Chinese medicinal herb, could reduce celecoxib dose and potentiate the growth-inhibitory effect in breast cancer cells. ABL enhanced the apoptotic effect of celecoxib in COX-2-expressing cells, but had little effect in COX-2-negative cells. The apoptosis induced by the combination treatment disappeared when COX-2 was knocked down, whereas the lack of apoptotic effects in COX-2-negative cells was reversed after COX-2 transfection. However, the combination treatment induced a G0/G1 phase arrest independent of whether or not the cells expressed COX-2. The G0/G1 arrest was attributed to a decreased expression of cyclinD1, cyclinE, CDK2 and CDK6, especially the upregulation of p21. In addition, inhibition of Akt and p38 signaling pathways was required by the synergism, as the constitutively active Akt and p38 protected cells against apoptosis and cell cycle arrest induced by the combination treatment. In vivo, administration of celecoxib and ABL were more effective than the individual agents against xenograft tumor growth. Thus, our data suggested that the combinatorial approach of celecoxib and ABL might be helpful for breast cancer treatment.

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