A novel inhibitory anti-invasive MAb isolated using phenotypic screening highlights AnxA6 as a functionally relevant target protein in pancreatic cancer.

BACKGROUND: Discovery and validation of new antibody tractable targets is critical for the development of new antibody therapeutics to address unmet needs in oncology. METHODS: A highly invasive clonal variant of the MDA-MB-435S cell line was used to generate monoclonal antibodies (MAbs), which were screened for anti-invasive activity against aggressive cancer cells in vitro. The molecular target of selected inhibitory MAb 9E1 was identified using immunoprecipitation/liquid chromatography-tandem mass spectrometry. The potential anti-tumour effects of MAb 9E1 were investigated in vitro together with immunohistochemical analysis of the 9E1 target antigen in normal and cancer tissues. RESULTS: MAb 9E1 significantly decreases invasion in pancreatic, lung squamous and breast cancer cells and silencing of its target antigen, which was revealed as AnxA6, leads to markedly reduced invasive capacity of pancreatic and lung squamous cancer in vitro. IHC using MAb 9E1 revealed that AnxA6 exhibits a high prevalence of membrane immunoreactivity across aggressive tumour types with restricted expression observed in the majority of normal tissues. In pancreatic ductal adenocarcinoma, high AnxA6 IHC score correlated with the presence of tumour budding at the invasive front of tumours (P=0.082), the presence of perineural invasion (P= <0.0001) and showed a weak correlation with reduced survival (P=0.2242). CONCLUSIONS: This study highlights the use of phenotypic hybridoma screening as an effective strategy to select a novel function-blocking MAb, 9E1 with anti-cancer activity in vitro. Moreover, through characterisation of the 9E1 target antigen, AnxA6, our findings support further investigation of AnxA6 as a potential candidate target for antibody-mediated inhibition of pancreatic cancer.

Exploiting highly ordered subnanoliter volume microcapillaries as microtools for the analysis of antibody producing cells.

The interrogation of highly diverse repertoires of heterogeneous cell populations on a single cell basis increases the likelihood that a cell with unique characteristics will be identified. We have developed a new single cell analysis system comprising millions of bundled subnanoliter volume bioincubation chambers for the identification and recovery of target specific antibody secreting cells (ASCs). This platform integrates dual surface screening with dedicated user driven data analysis and automated cell recovery enabling multiple biophysical parameters to be tracked for millions of antibody leads in parallel. This direct clone analysis and selection technology is a clear deviation from current microfabricated well-based approaches and offers drastically enhanced screening throughput, simultaneous dual surface analysis, and rapid automated single cell recovery. The technology is also applicable to screening both bacterial and mammalian antibody secreting cells. We demonstrate the implementation and feasibility of this platform in identifying target specific antibodies from bacterial, hybridoma, and B cell libraries.

7B7: a novel antibody directed against the Ku70/Ku80 heterodimer blocks invasion in pancreatic and lung cancer cells.

Development of more effective therapeutic strategies for cancers of high unmet need requires the continued discovery of disease-specific protein targets for therapeutic antibody targeting. In order to identify novel proteins associated with cancer cell invasion/metastasis, we present here an alternative to antibody targeting of cell surface proteins with an established role in invasion; our functional antibody screening approach involves the isolation and selection of MAbs that are primarily screened for their ability to inhibit tumour invasion. A clonal population of the Mia PaCa-2, a pancreatic ductal adenocarcinoma (PDAC) cell line, which displays a highly invasive phenotype, was used to generate MAbs with the objective of identifying membrane targets directly involved in cancer invasion. Selected MAb 7B7 can significantly reduce invasion in a dose-responsive manner in Mia PaCa-2 clone 3 and DLKP-M squamous lung carcinoma cells. Using immunoprecipitation and liquid chromatography-tandem mass spectrometry (LC-MS-MS) analysis, the target antigen of anti-invasive antibody, 7B7, was determined to be the heterodimeric Ku antigen, Ku70/80, a core protein composed of the Ku70 and Ku80 subunits which is involved in non-homologous end-joining (NHEJ) DNA repair. RNA interference-mediated knockdown of Ku70 and Ku80 resulted in a marked decrease in the invasive capacity of Mia PaCa-2 clone 3 and DLKP-M cells, indicating that Ku70/Ku80 is functionally involved in pancreatic and lung cancer invasion. Immunohistochemical analysis demonstrated Ku70/Ku80 immunoreactivity in 37 PDAC tumours, indicating that this heterodimer is highly expressed in this aggressive cancer type. This study demonstrates that a functional MAb screening approach coupled with immunoprecipitation/proteomic analyses can be successfully applied to identify functional anti-invasive MAbs and potential novel targets for therapeutic antibody targeting.

Synthesis, characterisation and biological evaluation of N-(ferrocenyl)naphthoyl amino acid esters as anticancer agents.

A series of N-(ferrocenyl)naphthoyl amino acid esters 5-18 has been prepared by coupling ferrocenyl naphthoic acids 3-4 to alpha-amino acids and linear amino acids in the presence of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and 1-hydroxybenzotriazole (HOBt). The compounds were fully characterised by a range of NMR spectroscopic techniques, UV-Vis spectroscopy, mass spectrometry and cyclic voltammetry. X-ray crystallographic studies of the intermediate compounds 1-2 were also performed. Biological evaluation of the intermediates 1-2 and N-(ferrocenyl)naphthoyl amino acid esters 5-18 was performed in the H1299 non-small cell lung cancer (NSCLC) cell line and the Sk-Mel-28 metastatic melanoma cell line. The intermediates 1-2 failed to produce an effect in either cell line. Compounds 5-18 exhibited a strong anti-proliferative effect in the H1299 cell line, whilst the Sk-Mel-28 cells were slightly more resistant to these compounds. N-(6-ferrocenyl-2-naphthoyl)-gamma-aminobutyric acid ethyl ester 17 shows a particularly high activity in both the H1299 cell line (IC(50) = 0.62 +/- 0.07 microM) and the Sk-Mel-28 cell line (IC(50) = 1.41 +/- 0.04 microM).

The 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, simvastatin, lovastatin and mevastatin inhibit proliferation and invasion of melanoma cells.

BACKGROUND: A number of recent studies have suggested that cancer incidence rates may be lower in patients receiving statin treatment for hypercholesterolemia. We examined the effects of statin drugs on in vitro proliferation, migration and invasion of melanoma cells. METHODS: The ability of lovastatin, mevastatin and simvastatin to inhibit the melanoma cell proliferation was examined using cytotoxicity and apoptosis assays. Effects on cell migration and invasion were assessed using transwell invasion and migration chambers. Hypothesis testing was performed using 1-way ANOVA, and Student's t-test. RESULTS: Lovastatin, mevastatin and simvastatin inhibited the growth, cell migration and invasion of HT144, M14 and SK-MEL-28 melanoma cells. The concentrations required to inhibit proliferation of melanoma cells (0.8-2.1 microave previously been achieved in a phase I clinical trial of lovastatin in patients with solid tumours, (45 mg/kg/day resulted in peak plasma concentrations of approximately 3.9 micro CONCLUSION: Our results suggest that statin treatment is unlikely to prevent melanoma development at standard doses. However, higher doses of statins may have a role to play in adjuvant therapy by inhibiting growth and invasion of melanoma cells.