Aptamer Internalization via Endocytosis Inducing S-Phase Arrest and Priming Maver-1 Lymphoma Cells for Cytarabine Chemotherapy

Abstract

The goal of precision therapy is to efficiently treat cancer without side effects. Aptamers are a class of small ligands composed of single-stranded oligonucleotides that bind to their targets with high affinity and specificity. In this study, we identified an ssDNA aptamer specifically targeting Maver-1 lymphoma cells with high binding affinity (Kd = 70±8 pmol/L). Interestingly, cellular cycle studies revealed that exposure of Maver-1 cells to synthetic aptamers triggered S-phase arrest of 40% of the cells (vs. 18% baseline). Confocal microscopy confirmed specific cell binding of aptamers and the resultant endocytosis into Maver-1 cells. Subsequent functional assays validated the fact that aptamer internalization into targeted cells is a prerequisite for Maver-1 cell growth inhibition. Importantly, aptamer-induced S-phase arrest induced enhanced chemotherapeutic results involving cytarabine, which primarily kills lymphoma cells at S-phase. Combination treatments revealed that aptamer re-exposure considerably primed Maver-1 cells for cytarabine chemotherapy, thus achieving a synergistic killing effect by reaching cell death rates as high as 61% (vs. 13% or 14% induced by aptamer or cytarabine treatment alone). These findings demonstrated that aptamers do not only act as molecular ligands but can also function as biotherapeutic agents by inducing S-phase arrest of lymphoma cells. In addition, logical combination of aptamer and cytarabine treatments ushers the way to a unique approach in precision lymphoma chemotherapy.

Epigenetic mediated zinc finger protein 671 downregulation promotes cell proliferation and tumorigenicity in nasopharyngeal carcinoma by inhibiting cell cycle arrest

“…The S phase cell cycle check point ensures synthesis of DNA and proteins and is a crucial regulator of cell cycle progression, while the G2/M checkpoint allows cells to enter mitosis [ 34 , 35 ]. Cyclin D1 and p21 cyclin-dependent kinases are major regulators of S phase progression [ 36 – 38 ]. Recent studies showed the transcriptionally repressive ZNF-KRAB domain can recruit KRAB-associated protein-1 (KAP1) [ 12 , 13 , 39 ] and other co-repressors, and KRAB-ZFP forms heterochromatin with chromobox 5 (CBX5), SET domain bifurcated 1 (SETDB1) and various histone deacetylases (HDACs) to epigenetically silence KRAB-ZNF target genes [ 40 – 42 ].…”

Aptamers as Delivery Agents of siRNA and Chimeric Formulations for the Treatment of Cancer

“…They exploit this effect in a combined treatment of lymphoma cells with a cytotoxic cytarabine. The lethal action of cytarabine is predominant over lymphoma cells in S-phase, and they show that several rounds of aptamer treatment was able to synergistically sensitize these cells to the lethal effect of cytarabine [68].…”

Oligonucleotide Aptamer-Mediated Precision Therapy of Hematological Malignancies

“… 117 , 118 Li et al. 119 developed a ssDNA aptamer that can specifically target Maver-1 lymphoma (B cell lymphoma) cells and Ig lambda-like polypeptide. The functional studies revealed selective internalization of aptamers into Maver-1 lymphoma cells, triggering cell cycle S-phase arrest and cellular growth inhibition.…”

“…These results demonstrate the importance of aptamers in synergistic biotherapy via cell cycle regulation and chemotherapy of lymphoma. 119 …”