ADAM-17: a novel therapeutic target for triple negative breast cancer

BACKGROUND

Validated targeted therapy is currently unavailable for patients with invasive breast cancer negative for oestrogen receptors, progesterone receptors and HER2 [i.e., those with triple-negative (TN) disease]. ADAM-17 is a protease involved in the activations of several ligands that bind to and promotes intracellular signalling from the EGFR/HER family of receptors.

PATIENTS AND METHODS

Expression of ADAM-17 was measured in 86 triple-negative and 96 non-triple-negative breast cancers. The ADAM-17 specific inhibitor, PF-5480090 (TMI-002, Pfizer) was tested in a panel of breast cancer cell lines for effects on functional outputs.

RESULTS

In this study we show using both Western blotting and immunohistochemistry that ADAM-17 is expressed at significantly higher levels in TN than non-TN breast cancers. Using a panel of breast cancer cell lines in culture, PF-5480090 was found to decrease release of the EGFR ligand, TGF-alpha, decrease levels of phosphorylated EGFR and block cell proliferation in a cell-type-dependent manner. Potentially important was the finding of a significant and moderately strong correlation between ADAM-17 activity and extent of proliferation inhibition by PF-5480090 (r = 0.809; p = 0.003; n = 11). Pretreatment of cell lines with PF-5480090 enhanced response to several different cytotoxic and anti-EGFR/HER agents.

CONCLUSION

It is concluded that inhibition of ADAM-17, especially in combination with chemotherapy or anti-EGFR/HER inhibitors, may be a new approach for treating breast cancer, including patients with TN disease.

ADAM17 as a novel therapeutic target for HER2-positive breast cancer

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Background: Although the HER2 gene is amplifiend/overexpressed in 15-20% of breast cancers, only a proportion of these patients benefit from anti-HER2 therapy. Clearly additional biomarkers and/or therapeutic targets are necessary to enhance efficacy and improve outcome in these patients. Here, we tested the hypothesis that inhibition of ADAM17-mediated release of HER ligands may enhance response to trastuzumab and lapatinib. Methods: The ADAM17-selective inhibitor, PF-5480090 (Pfizer) both alone and in combination with lapatinib, trastuzumab or 5FU was tested for potential growth inhibitory effects on a panel of 4 HER2-positive breast cancer cell lines (BT474, MDA-MB-453, SKBR3 and JIMT-1). Results: Using the MTT viability assay, treatment with 1 µM TMI-2 resulted in a significant reduction in cell proliferation compared to vehicle control in BT474 (p=0.01), MDA-MB-453 (p < 0.005), JIMT-1 (p=0.002) and SKBR3 cells (p < 0.005). Addition of PF-5480090 to lapatinib resulted in a significant reduction in cell growth compared to lapatinib alone (JIMT-1: p < 0.005; SKBR3: p < 0.005; MDA-MB-453: p < 0.005), while addition of PF-5480090 to trastuzumab resulted in significant reduction in cell growth compared to trastuzumab alone (JIMT-1: p < 0.005; SKBR3: p < 0.005; MDA-MB-453: p=0.001). Addition of PF-5480090 to 5FU resulted in significant reduction in growth compared to 5FU alone (JIMT-1: p < 0.005; SKBR3: p < 0.005; MDA-MB-453: p=0.001). Consistent with its ability to block proliferation, addition of PF-5480090 significantly reduced release of TGFalpha (BT474: p=0.003; JIMT1: p=0.023; SKBR3: p=0.036 and MDA-MB-453: p=0.014). Conclusions: Inhibitionof ADAM17 resulted in growth inhibitory responses in HER2-positive breast cancer cell lines. Furthermore, addition of PF-5480090 to lapatinib, trastuzumab or 5FU resulted in significant growth inhibition compared to these agents alone. We propose that inhibition of ADAM17 may be used in combination with existing treatments for HER2-positive breast cancer. Acknowledgement. The authors thank SFI (SRC award, 08/SRC/B1410 to MTCI) for funding this work.

Abstract 1845: ADAM10: A new player in breast cancer progression

Background: The ADAMs are a family of proteases, best known for their role in releasing the extracellular domain of transmembrane proteins. One of the ADAMs, i.e., ADAM10, is involved in the activation of 2 important signaling systems controlling cell growth, invasion and metastasis, i.e. the EGFR and NOTCH signaling systems. Because of its ability to activate both EGFR and NOTCH, ADAM10 is likely to play a role in cancer formation or progression. The aim of this study was therefore to investigate the role of ADAM10 in breast cancer and test its therapeutic potential, especially in patients with the triple-negative form of this disease. Materials and Methods: ADAM10 mRNA expression was examined in a pooled collection of publically available databases (n ∼ 4000). ADAM10 protein was examined in a cohort of 120 breast tumor extracts by ELISA. In addition, ADAM10 expression was decreased by RNAi and the effects of this on cell proliferation, invasion and migration were determined. Using the novel ADAM10 inhibitor GI254023X (GSK), we examined the effect of ADAM10 inhibition on a panel of 13 breast cancer cell lines. Results: Using the pooled collection of databases, ADAM10 mRNA was found to be significantly elevated in HER2+ breast cancer compared to other subtypes (p &lt; 0.0001). High ADAM10 mRNA expression was also observed in basal like breast cancer and was associated with poorer overall survival in this subgroup (p = 0.0196). In a cohort of 120 breast tumor extracts, ADAM10 protein was found to be significantly higher in ER-negative compared to ER-positive tumors (p = 0.005), in high grade versus low grade tumors (p &lt; 0.0001), and in younger than older women (p = 0.018). Downregulation of ADAM10 in MDA-MB-231 breast cancer cells resulted in a significant reduction in invasion (p = 0.0006) and cellular migration (p = 0.0002). Treatment of 13 breast cancer cell lines with GI254023X resulted in variable growth inhibition (from 0 to 52%). Furthermore, GI254023X significantly decreased invasion in the MDA-MB-231 cell line (p = 0.001). Conclusions: Our findings of a correlation between ADAM10 and features of aggressive disease and the fact that its downregulation/inhibition decreased growth, invasion and migration suggests that this ADAM10 protease is involved in the progression of breast cancer. Inhibition of ADAM10 with GI254023X may be a new treatment for breast cancer. Acknowledgements: The authors thank SFI and the Molecular Therapeutics for Cancer Ireland (SRC award, 08/SRC/B1410 to MTCI) for funding this work.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1845. doi:1538-7445.AM2012-1845

The ADAMs family of proteases: new biomarkers and therapeutic targets for cancer?

The ADAMs are transmembrane proteins implicated in proteolysis and cell adhesion. Forty gene members of the family have been identified, of which 21 are believed to be functional in humans. As proteases, their main substrates are the ectodomains of other transmembrane proteins. These substrates include precursor forms of growth factors, cytokines, growth factor receptors, cytokine receptors and several different types of adhesion molecules. Although altered expression of specific ADAMs has been implicated in different diseases, their best-documented role is in cancer formation and progression. ADAMs shown to play a role in cancer include ADAM9, ADAM10, ADAM12, ADAM15 and ADAM17. Two of the ADAMs, i.e., ADAM10 and 17 appear to promote cancer progression by releasing HER/EGFR ligands. The released ligands activate HER/EGFR signalling that culminates in increased cell proliferation, migration and survival. Consistent with a causative role in cancer, several ADAMs are emerging as potential cancer biomarkers for aiding cancer diagnosis and predicting patient outcome. Furthermore, a number of selective ADAM inhibitors, especially against ADAM10 and ADAM17, have been shown to have anti-cancer effects. At least one of these inhibitors is now undergoing clinical trials in patients with breast cancer.

Chemotherapy-associated recurrent pneumothoraces in lymphangioleiomyomatosis

Lymphangioleiomyomatosis is a rare cause of pneumothorax in women. We present the case of a 48-year-old woman with lymphangioleiomyomatosis, who had never had a pneumothorax prior to commencing chemotherapy for breast cancer. During chemotherapy she developed 3 pneumothoraces and 2 episodes of pneumomediastinum. We suggest that the pneumothoraces were caused by the chemotherapy. To our knowledge, this is the first reported case of chemotherapy triggering pneumothoraces in a woman with lymphangioleiomyomatosis.