Annexin-A1: The culprit or the solution?

Annexin-A1 has a well-defined anti-inflammatory role in the innate immune system, but its function in adaptive immunity remains controversial. This glucocorticoid-induced protein has been implicated in a range of inflammatory conditions and cancers, as well as being found to be overexpressed on the T cells of patients with autoimmune disease. Moreover, the formyl peptide family of receptors, through which annexin-A1 primarily signals, has also been implicated in these diseases. In contrast, treatment with recombinant annexin-A1 peptides resulted in suppression of inflammatory processes in murine models of inflammation. This review will focus on what is currently known about annexin-A1 in health and disease and discuss the potential of this protein as a biomarker and therapeutic target.

A therapeutic antibody targeting annexin-A1 inhibits cancer cell growth in vitro and in vivo.

In this study we conducted the first investigation to assess the efficacy of a novel therapeutic antibody developed to target annexin-A1 (ANXA1). ANXA1 is an immunomodulatory protein which has been shown to be overexpressed in, and promote the development and progression of, several cancer types. In particular, high ANXA1 expression levels correlate with poorer overall survival in pancreatic and triple-negative breast cancers, two cancers with considerable unmet clinical need. MDX-124 is a humanised IgG1 monoclonal antibody which specifically binds to ANXA1 disrupting its interaction with formyl peptide receptors 1 and 2 (FPR1/2). Here we show that MDX-124 significantly reduced proliferation (p < 0.013) in a dose-dependent manner across a panel of human cancer cell lines expressing ANXA1. The anti-proliferative effect of MDX-124 is instigated by arresting cell cycle progression with cancer cells accumulating in the G1 phase of the cell cycle. Furthermore, MDX-124 significantly inhibited tumour growth in both the 4T1-luc triple-negative breast and Pan02 pancreatic cancer syngeneic mouse models (p < 0.0001). These findings suggest ANXA1-targeted therapy is a viable and innovative approach to treat tumours which overexpress ANXA1.

HDX-MS for Epitope Characterization of a Therapeutic ANTIBODY Candidate on the Calcium-Binding Protein Annexin-A1.

Annexin-A1 (ANXA1) belongs to a class of highly homologous Ca2+-dependent phospholipid-binding proteins. Its structure consists of a core region composed of four homologous repeats arranged in a compact, hydrolysis-resistant structure and an N-terminal region with a Ca2+-dependent conformation. ANXA1 is involved in several processes, including cell proliferation, apoptosis, metastasis, and the inflammatory response. Therefore, the development of antibodies blocking selected regions on ANXA1 holds great potential for the development of novel therapeutics treating inflammatory and cancer diseases. Here, we report the interaction site between an ANXA1-specific antibody known to inhibit T cell activation without adverse cytotoxic effects and ANXA1 using amide hydrogen-deuterium exchange mass spectrometry (HDX-MS). For the epitope determination, we applied two bottom-up HDX-MS approaches with pepsin digestion in solution and immobilized on beads. Both strategies revealed the interaction region within domain III of ANXA1 in Ca2+-bound conformation. The antibody-binding region correlates with the hydrophobic binding pocket of the N-terminal domain formed in the absence of calcium. This study demonstrates that even cryptic and flexible binding regions can be studied by HDX-MS, allowing a fast and efficient determination of the binding sites of antibodies which will help to define a mode of action profile for their use in therapy.

Cross-sectional associations between angiotensin-converting enzyme inhibitor use and cancer diagnosis in US adults.

The objective of the present study was to investigate the association between angiotensin-converting enzyme (ACE) inhibitor use and cancer incidence (overall, and breast, prostate, and colorectal cancers specifically) in a large representative sample of US adults. Cross-sectional data on cancer diagnosis, timing of cancer diagnosis, ACE inhibitor use, and other characteristics were extracted from 49 512 adults aged ≥ 20 years participating in the National Health and Nutrition Examination Survey (1999-2016). Multivariable-logistic and propensity score matching (PSM) regressions examined the relationship between pre-diagnosis use of ACE inhibitors and diagnosis of all cancers, and breast, prostate, and colorectal cancers specifically. Overall, we observed an increased likelihood of cancer diagnosis [odds ratio (OR) 1.269, 95% confidence interval (CI) 1.088-1.480] among those who used ACE inhibitors compared to non-ACE inhibitor use, and for prostate cancer diagnosis (OR 1.438, 95% CI 1.090-1.897), after adjusting for age, sex, body mass index, race/ethnicity, educational attainment, physical activity, alcohol drinking status, smoking status, and high blood pressure. PSM regression retrieved more conservative estimates such that the increased likelihood of cancer diagnosis was only observed when comparing ACE inhibitor users with non-drug users (OR 1.022, 95% CI 1.016-1.027). Compared with non-ACE inhibitor use, ACE inhibitor use was associated with an increased risk of prostate cancer. In conclusion, in this large representative sample of US adults, it was found that ACE inhibitor use may have a marginal influence on some cancers.