Louise Flanagan

Targeting ADAM-17 with an inhibitory monoclonal antibody has antitumour effects in triple-negative breast cancer cells.

Background:Identification and validation of a targeted therapy for triple-negative breast cancer (TNBC), that is, breast cancers negative for oestrogen receptors, progesterone receptors and HER2 amplification, is currently one of the most urgent problems in breast cancer treatment. EGFR is one of the best-validated driver genes for TNBC. EGFR is normally activated following the release of ligands such as TGFα, mediated by the two MMP-like proteases ADAM (a disintegrin and metalloproteinase)-10 and ADAM-17. The aim of this study was to investigate the antitumour effects of a monoclonal antibody against ADAM-17 on an in vitro model of TNBC.Methods:We investigated an inhibitory cross-domain humanised monoclonal antibody targeting both the catalytic domain and the cysteine-rich domain of ADAM17-D1(A12) in the HCC1937 and HCC1143 cell lines.Results:D1(A12) was found to significantly inhibit the release of TGFα, and to decrease downstream EGFR-dependent cell signalling. D1(A12) treatment reduced proliferation in two-dimensional clonogenic assays, as well as growth in three-dimensional culture. Furthermore, D1(A12) reduced invasion of HCC1937 cells and decreased migration of HCC1143 cells. Finally, D1(A12) enhanced cell death in HCC1143 cells.Conclusion:Our in vitro findings suggest that targeting ADAM-17 with D1(A12) may have anticancer activity in TNBC cells.

mTOR in breast cancer: differential expression in triple-negative and non-triple-negative tumors.

Triple-negative breast cancer (TNBC) is defined by the absence of estrogen receptors (ER), progesterone receptors (PR) and overexpression of HER2. Targeted therapy is currently unavailable for this subgroup of breast cancer patients. mTOR controls cancer cell growth, survival and invasion and is thus a potential target for the treatment of patients with TNBC. Using immunohistochemistry, mTOR and p-mTOR were measured in 89 TNBCs and 99 non-TNBCs. While mTOR expression was confined to tumor cell cytoplasm, p-mTOR staining was located in the nucleus, perinuclear area and in the cytoplasm. Potentially important, was our finding that nuclear p-mTOR was found more frequently in triple-negative than non triple-negative cancers (p < 0.001). These results suggest that mTOR may play a more important role in the progression of TNBC compared to non-TNBC. Based on these findings, we conclude that mTOR may be a new target for the treatment of triple-negative breast cancer.

The Role of Vitamin D3 and Antiestrogens in Modulating Apoptosis of Breast Cancer Cells and Tumors

The death of cells can be classified as either necrosis, usually the result of tissue damage or insult, or apoptosis, an active process of cellular self-destruction. Apoptosis can be distinguished by its characteristic morphological features such as cell shrinkage, nuclear condensation, and irreversible DNA fragmentation (Tenniswood et al., 1992). In most cell types, apoptosis requires gene transcription and activation of specific proteases which mediate destruction of the cell without release of intracellular contents or initiation of an immune response (Vaux and Strasser, 1996; Zhivotovsky et al., 1997). In addition to genes linked to activation of apoptosis, genes associated with repression of apoptosis, such as bcl-2, have been identified (Craig, 1995; Yang and Korsmeyer, 1996). Thus, the regulation of apoptosis within a cell reflects a balance between antiapoptotic and proapoptotic gene products. Extracellular influences on this balance include physiological triggers of apoptosis, cell-type-specific “survival factors,” and the components of the extracellular matrix (Tenniswood et al., 1992; Goberdhan et al., 1996; Merio et al., 1997). The recognition that mutations in critical components or regulators of the apoptotic pathway, such as p53 and bcl-2, may be linked to cancer development or therapeutic responsiveness has emphasized the importance of apoptosis in the context of tumor biology (Barry et al., 1990; Lowe et al., 1993; Yang and Korsmeyer, 1996).

Investigation of molecular alterations of AKT-3 in triple-negative breast cancer

Triple‐negative breast cancer (TNBC) is responsible for a disproportionate number of breast cancer (BC) deaths, owing to its intrinsic aggressiveness and a lack of treatment options, especially targeted therapies. Thus, there is an urgent need for the development of better targeted treatments for TNBC. Molecular alteration of AKT‐3 was previously reported in oestrogen receptor (ER)‐positive BC. AKT‐3 has also been suggested to play a role in hormone‐unresponsive BC. The aim of this study was to investigate molecular alterations of AKT‐3 in TNBC, to perform associated survival analysis, and to compare these findings with the incidence of AKT‐3 molecular alterations in ER‐positive BC.

Delineating transcriptional networks of prognostic gene signatures refines treatment recommendations for lymph node-negative breast cancer patients

The majority of women diagnosed with lymph node‐negative breast cancer are unnecessarily treated with damaging chemotherapeutics after surgical resection. This highlights the importance of understanding and more accurately predicting patient prognosis. In the present study, we define the transcriptional networks regulating well‐established prognostic gene expression signatures. We find that the same set of transcriptional regulators consistently lie upstream of both ‘prognosis’ and ‘proliferation’ gene signatures, suggesting that a central transcriptional network underpins a shared phenotype within these signatures. Strikingly, the master transcriptional regulators within this network predict recurrence risk for lymph node‐negative breast cancer better than currently used multigene prognostic assays, particularly in estrogen receptor‐positive patients. Simultaneous examination of p16INK4A expression, which predicts tumours that have bypassed cellular senescence, revealed that intermediate levels of p16INK4A correlate with an intact pRB pathway and improved survival. A combination of these master transcriptional regulators and p16INK4A, termed the OncoMasTR score, stratifies tumours based on their proliferative and senescence capacity, facilitating a clearer delineation of lymph node‐negative breast cancer patients at high risk of recurrence, and thus requiring chemotherapy. Furthermore, OncoMasTR accurately classifies over 60% of patients as ‘low risk’, an improvement on existing prognostic assays, which has the potential to reduce overtreatment in early‐stage patients. Taken together, the present study provides new insights into the transcriptional regulation of cellular proliferation in breast cancer and provides an opportunity to enhance and streamline methods of predicting breast cancer prognosis.