Epithelial to mesenchymal transition (EMT) is believed to be crucial for primary tumors to escape their original residence and invade and metastasize. To properly define EMT, there is a need for ligands that can identify this phenomenon in tumor tissue and invivo. A phage-display selection screening was performed to select novel binding phage peptides for identification of EMT in breast cancer. Epithelial breast cancer cell line, MCF-7 was transformed to mesenchymal phenotype by TGF-β treatment and was used for selection. Breast fibroblasts were used for subtractive depletion and breast cancer metastatic cell lines MDA-MB-231, T47D-shNMI were used for specificity assay. The binding peptides were identified, and their binding capacities were confirmed by phage capture assay, phage-based ELISA, immunofluorescence microscopy. The phage peptide bearing the 7-amino acid sequence, LGLRGSL, demonstrated selective binding to EMT phenotypic cells (MCF-7/TGF-β and MDA-MB-231) as compared to epithelial subtype, MCF-7, T47D and breast fibroblasts (Hs578T). The selected phage was also able to identify metastatic breast cancer tumor in breast cancer tissue microarray (TMA). These studies suggest that the selected phage peptide LGLRGSL identified by phage-display library, showed significant ability to bind to mesenchymal-like breast cancer cells/ tissues and can serve as a novel probe/ligand for metastatic breast cancer diagnostic and imaging.

Most available therapeutic drugs efficiently treat tumors; however, absence of specificity has deleterious effects on patients. Identifying a tumor ablation method that has specificity with minimal to no side effects is needed. Phage display allows for expression of peptide and protein libraries on the surface of phage with a diversity of 109 peptides of different permutations, which leads to the selection of peptides and proteins, with high affinity and specificity. Phage display can be used as a tool to identify specific targets using a pIII phage library for identification of cell surface markers. To do so, we performed an initial depletion assay to isolate specific phages that express an affinity to human cells. We isolated a phage diversity of 10-2 from 109. Subsets of this population were used to identify phage and breast cancer cell interaction in vitro using an ELISA assay. Briefly, phages were exposed to epithelial and mesenchymal breast cancer cells and fibroblast cells. We have identified a phage profile that selectively targets tumor cells based on their transition from epithelial to mesenchymal. Interestingly, PE-26, a phage subset, indicated a greater affinity for more mesenchymal-like tumor cells. Moreover, we identified a 5-fold increase in the binding affinity for MDA-MB-231 and MCF-7 (overexpressed with TGF-β) in comparison to the control fibroblast cells. Additionally, PE-21 demonstrates a 6-fold increased affinity for breast cancer cells when contrasted with our control fibroblast cells. Our data provide further support that the identified phage profiles exhibit a preferential affinity for more mesenchymal-like tumor cells, which are known to be aggressive. This suggests their potential chemotherapeutic capability. Our future endeavors include further validation of selected phages and development of peptides to be employed as imaging agents to study EMT in vivo and as diagnostics to detect circulating tumor cells. Citation Format: Kelvin M. Jones, Rajeev Samant, Shree Singh, Deepa Bedi. Identification of peptides binding to mesenchymal subtype breast cancer from phage display peptide library [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1078.

Boron nitride is a material similar to carbon in its ability to adopt numerous molecular forms, including two-dimensional sheets and three-dimensional cages and nanotubes. Boron nitride single molecules, such as B12N12, have isomeric forms that include rings and sheets, as well as cage forms analogous and isoelectronic to the carbon fullerenes. Such cages tend to be composed of squares and hexagons to allow perfect alternation of boron and nitrogen atoms, which is possible because of the 1 : 1 ratio of boron-to-nitrogen atoms. What about molecules in which this 1 : 1 ratio does not apply? In the current study, theoretical calculations are carried out on molecules of B10N14 to determine energetically favorable isomers. Density functional theory is used in conjunction with Dunning basis sets. Cage, sheet, and ring isomers are considered. Energetic trends are calculated and discussed, in comparison to comparable studies on B12N12.