A fluorescent quantum dot conjugate to probe the interaction of Enterolobium contortisiliquum trypsin inhibitor with cancer cells

Author(s):Show less -

Santos, Natalia R. M. ; de Oliveira, Weslley F. ; Cabrera, Mariana P. ; Bezerra Filho, Clovis M. ; Patriota, Leydianne L. S. ; Napolea, Thiago H. ; Paiva, Patricia M. G. ; Oliva, Maria Luiza V. ; Cabral Filho, Paulo E. ; Fontes, Adriana ; Correia, Maria T. S.

• Document type: Journal article
• Source: International Journal of Biological Macromolecules; v. 252, p. 7-pg., 2023-12-01.

Abstract

Serine proteases play crucial biological roles and have their activity controlled by inhibitors, such as the EcTI, a serine protease inhibitor purified from Enterolobium contortisiliquum seeds, which has anticancer activity. This study aimed to conjugate EcTI with quantum dots (QDs), fluorophores with outstanding optical properties, and investigate the interaction of QDs-EcTI nanoprobe with cancer cells. The conjugation was evaluated by fluo-rescence correlation spectroscopy (FCS) and fluorescence microplate assay (FMA). EcTI inhibitory activity after interaction with QDs was also analyzed. From FCS, the conjugate presented a hydrodynamic diameter about 4x greater than bare QDs, suggesting a successful conjugation. This was supported by FMA, which showed a relative fluorescence intensity of ca. 3815% for the nanosystem, concerning bare QDs or EcTI alone. The EcTI inhibitory activity remained intact after its interaction with QDs. From flow cytometry analyses, approximately 62% of MDA-MB-231 and 90% of HeLa cells were labeled with the QD-EcTI conjugate, suggesting that their membranes have different protease levels to which EcTI exhibits an affinity. Concluding, the QD-EcTI represents a valuable nanotool to study the interaction of this inhibitor with cancer cells using fluorescence-based techniques with the potential to unravel the intricate dynamics of interplays between proteases and inhibitors in cancer biology. (AU)

• FAPESP's process: 17/06630-7 - Fragments derived from the structure of protease inhibitors with selectivity for inhibition of mammalian and microorganism enzymes and its role as an anti-inflammatory, antimicrobial, antithrombotic and anti- tumor agent: mechanism of action
• Grantee: Maria Luiza Vilela Oliva
• Support Opportunities: Research Projects - Thematic Grants