Combination of dl922-947 Oncolytic Adenovirus and G-Quadruplex Binders Uncovers Improved Antitumor Activity in Breast Cancer

Abstract

G-quadruplexes (G4s) are nucleic secondary structures characterized by G-tetrads. G4 motif stabilization induces DNA damage and cancer cell death; therefore, G4-targeting small molecules are the focus of clinical investigation. DNA destabilization induced by G4 ligands might potentiate the anticancer activity of agents targeting DNA or inhibiting its repair such as oncolytic viruses. This study represents the first approach combining G4 ligands, BRACO-19 (B19), pyridostatin (PDS), and the adenovirus dl922-947 in breast cancer cells. We demonstrated that G4 binders and dl922-947 induce cytotoxicity in breast cancer cells (MDA-MB-231 and MCF-7) and at higher doses in other neoplastic cell lines of thyroid (BHT-101 cells) and prostate (PC3 cells). G4 binders induce G4 motifs distributed in the S and G2/M phases in MCF-7 cells. G4 binder/dl922-947 combination increases cell cytotoxicity and the accumulation in subG0/G1. Indeed, G4 binders favor viral entry and replication with no effect on coxsackie and adenovirus receptor. Notably, dl922-947 induces G4 motifs and its combination with PDS potentiates this effect in MCF-7 cells. The agents alone or in combination similarly enhanced cell senescence. Additionally, PDS/dl922-947 combination inactivates STING signaling in MDA-MB-231 cells. Our results suggest that G4 binder/virotherapy combination may represent a novel therapeutic anticancer approach.

Targeting G-quadruplex motifs interferes with differentiation of adipose-derived mesenchymal stem cells

“…Beyond the reported potential of G4 motifs as anticancer targets [ 15 , 21 ], studies dealing with how these secondary structures and their ligands might regulate normal cell functions under homeostatic conditions are poorly investigated. G4 structures detected throughout mammalian genome regulate several processes associated with gene expression and genome duplication.…”

“…We have observed that Braco-19 activity in breast cancer cells is mediated by mechanisms ranging from apoptosis to immunogenic cell death, depending on the invasiveness of tumor cell phenotype [ 4 ]. In addition, we have very recently demonstrated improved anticancer effects using Braco-19 in combination with an oncolytic adenovirus by increased viral entry and replication in breast cancer cell lines [ 15 ].…”

“…Cells were fixed with 50% trichloroacetic acid for at least 2 h at 4 °C, washed with distilled and de-ionized water, air-dried and stained 30 min with 0.4% sulforhodamine B (SRB) in 1% acetic acid. Unbound dye was removed, and 10 mM Tris solution (pH 7.5) was added to dissolve the protein-bound dye [ 14 , 15 ]. Cell survival was assessed by optical density determination at 490 nm by Glomax Discover Microplate Reader (Promega, Madison, WI, USA).…”

“…Cells were incubated 1 h at room temperature, washed with PBT and re-suspended in PBT containing Alexa Fluor 488 (Invitrogen, USA, #A11001, 1:100) at darkness. After 30 min, cells were washed with PBT containing RNaseA (Roche) (0.4 U) and re-suspended in PI (Sigma) (0.015 mol/L) for 20 min at room temperature [ 15 ].…”

Targeting of G‐quadruplex DNA with 99mTc(I)/Re(I) Tricarbonyl Complexes Carrying Pyridostatin Derivatives

“…[6][7][8][9] Several reports have been published on classical DNA intercalators labeled with medical radiometals, comprising mainly 99m Tc-labeled molecules and preclinical studies with cellular models of cancer. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] By contrast, studies on radiometalated G4 binders are scarcer; only more recently a few 64 Cu and 111 In-labeled complexes were reported. The rationale justifying the study of these 64 Cu-and 111 In-labeled G4-binders relied mainly on their usefulness to non-invasively image the in vivo biodistribution of metalated G4-binding anticancer drugs by PET and SPECT, respectively.…”