Supplementary Table S1 shows nucleotide sequence of the scDb-hERG1-β1. Supplementary Table S2 reports a list of primers. Supplementary Figure S1 dot blot and Coomassie staining of different scDb-hERG1-β1 clones. Supplementary Figure S2 shows peptide ELISA assay performed using different peptides. Supplementary Figure S3 shows Figure S3 cell ELISA assay performed using different cancer cell lines. Supplementary Figure S4 shows dose-dependence curves of different cell lines treated with scDb-hERG1-β1. Supplementary Figure S5 shows cell cycle plots. Supplementary Figure S6 shows spheroid growth curves of different cancer cell lines. Supplementary Figure S7 shows microscopic appearance of spheroids of PANC-1, HCT116 and MIAPaca 2 cells. Supplementary Figure S8 shows sequence alignments
ARTICLE ABSTRACT
mAbs, either mono- or bispecific (bsAb), represent one of the most successful approaches to treat many types of malignancies. However, there are certain limitations to the use of full length mAbs for clinical applications, which can be overcome by engineered antibody fragments. The aim of this study was to develop a small bsAb, in the format of a single-chain diabody (scDb), to efficiently target two proteins, the hERG1 potassium channel and the β1 subunit of integrin receptors, which specifically form a macromolecular complex in cancer cells. We provide evidence that the scDb we produced binds to the hERG1/β1 complex in cancer cells and tissues, but does not bind to the hERG1 channel in nonpathologic tissues, in particular the heart. The scDb-hERG1-β1 (i) downregulates the formation of the hERG1/β1 complex, (ii) inhibits Akt phosphorylation and HIF-1α expression, and (iii) decreases cell survival, proliferation, and migration in vitro. These effects only occur in cancer cells (either colon, pancreatic, or breast), but not in normal cells. In vivo, the scDb-hERG1-β1 shows a good pharmacokinetic profile, with a half-life of 13.5 hours and no general, cardiac, or renal toxicity when injected intravenously up to the dose of 8 mg/kg. The scDb-hERG1-β1 accumulates into subcutaneous xenografted tumors, arising from either colon or pancreatic human cancer cells, and induces a reduction of tumor growth and vascularization. Overall, the scDb-hERG1-β1 represents an innovative single-chain bispecific antibody for therapeutic applications in solid cancers that overexpress the hERG1/β1 integrin signaling complex.
