Aptamer-based targeted Delivery of a G-quadruplex Ligand in Cervical Cancer Cell

In this work, the team led by Carla Cruz from the Health Sciences Research Centre of the University of Beira Interior (CICS-UBI) has developed a strategy for the selective delivery of an anticancer compound to cervical cancer cells, using AS1411 as vehicle. AS1411 aptamer is a guanine-rich oligonucleotide which binds and recognizes protein nucleolin that is overexpressed on the surface of cancer cells, showing anticancer activity on a variety of cancer cell types. The anticancer compound, an acridine derivative, has the ability to bind regions of the genome capable of folding into DNA secondary structures named G-quadruplex, characterized by the non-canonical guanine base pairing. The results demonstrate the potential of using AS1411 for the selective delivery of drugs into cervical cancer cells, limiting their off-target effects.

Authors and affiliations:
Josué Carvalho (CICS-UBI - Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, 6200-506, Covilhã, Portugal) Artur Paiva (Unidade de Gestão Operacional em Citometria, Centro Hospitalar e Universitário de Coimbra (CHUC), Coimbra, Portugal; CIMAGO/iCBR/CIBB, Faculdade de Medicina da Universidade de Coimbra, Coimbra, Portugal; Instituto Politécnico de Coimbra, ESTESC-Coimbra Health School, Ciências Biomédicas Laboratoriais, Coimbra, Portugal)

Maria Paula Cabral Campello (Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10 (km 139,7), 2695-066, Bobadela, LRS, Portugal)

António Paulo (Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10 (km 139,7), 2695-066, Bobadela, LRS, Portugal)

Jean-Louis Mergny (Univ. Bordeaux, ARNA laboratory, INSERM, U1212, CNRS UMR 5320, IECB, F-33600, Pessac, France; Institute of Biophysics, AS CR, v.v.i. Kralovopolska 135, 612 65, Brno, Czech Republic)

Gilmar F. Salgado (Univ. Bordeaux, ARNA laboratory, INSERM, U1212, CNRS UMR 5320, IECB, F-33600, Pessac, France)

João António Queiroz (CICS-UBI - Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, 6200-506, Covilhã, Portugal)

Carla Cruz (CICS-UBI - Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, 6200-506, Covilhã, Portugal)

Abstract:
AS1411 is a G-rich DNA oligonucleotide that functions as an aptamer of protein nucleolin, found at high levels on the surface of cancer cells but not on the surface of normal cells. Herein, we have studied AS1411 as a supramolecular carrier for the delivery of an acridine-based G-quadruplex ligand, C8, to HeLa cancer cells. Two AS1411 derivatives, LNA-AS1411 and U-AS1411, were also tested, in an attempt to compare AS1411 pharmacological properties. The results showed that AS1411-C8 complexation was made with great binding strength and that it lowered the ligand’s cytotoxicity towards non-malignant cells. This effect was suggested to be due to a decreased internalization of the complexed versus free C8 as shown by flow cytometry. The AS1411 derivatives, despite forming a stable complex with C8, lacked the necessary tumour-selective behaviour. the binding of C8 to AS1411 G-quadruplex structure did not negatively affect the recognition of nucleolin by the aptamer. The AS1411-C8 repressed c-MYC expression at the transcriptional level, possibly due to C8 ability to stabilize the c-MYC promoter G-quadruplexes. Overall, this study demonstrates the usefulness of AS1411 as a supramolecular carrier of the G-quadruplex binder C8 and the potential of using its tumour-selective properties for the delivery of ligands for cancer therapy.

Journal: Scientific Reports

Link: https://www.nature.com/articles/s41598-019-44388-9