Aptamer-Based Therapeutic Approaches to Target Cancer Stem Cells

Abstract

Cancer stem cells (CSCs) are believed to be a principal cellular source for tumour progression and therapeutic drug resistance as they are capable of self-renewal and can differentiate into cancer cells. Importantly, CSCs acquire the ability to evade the killing effects of cytotoxic agents through changes at the genetic, epigenetic and micro-environment levels. Therefore, therapeutic strategies targeting CSCs hold great potential as an avenue for cancer treatment. Aptamers or “chemical antibodies” are a group of single-stranded nucleic acid (DNA or RNA) oligonucleotides with distinctive properties such as smaller size, lower toxicity and less immunogenicity compared to conventional antibodies. They have been frequently used to deliver therapeutic payloads to cancer cells and have achieved encouraging anti-tumour effects. This review discusses progress in CSC evolution theory and the role of aptamers to target CSCs for cancer treatment. Challenges of aptamer-mediated CSC targeting approaches are also discussed.

Aptamers: Uptake mechanisms and intracellular applications

“…The recently developed cancer specific aptamers targeting cancer plasma membrane have been well functionalized to delivery therapeutic small RNAs, small molecules, antibodies, and peptides, even novel cancer specific biomarker discoveries [82]. The RNA aptamers targeting the cancer stem cell (CSC) surface marker CD133 [83] and other markers such as CD117, EpCAM, prostate CSC, HER2, and MRP1 have been well characterized for the cancer specific therapeutic effects [84]. Along with these aptamers, cancer specific point mutations and isotypes are very attractive targets for the specific anti-cancer effects.…”

Overcoming Drug Resistance in Colon Cancer by Aptamer-Mediated Targeted Co-Delivery of Drug and siRNA Using Grapefruit-Derived Nanovectors

“…To enhance tumor targeting, the nanovector surface is usually modified with a ligand [9] or antibody [10]. Aptamers identified by an in vitro selection procedure known as systematic evolution of ligands by exponential enrichment (SELEX) have broad medical applications as drug delivery ligands due to their low immunogenicity and toxicity, high binding affinity, specificity, and wide range of targets [11,12].…”

Aptamers for Diagnostics with Applications for Infectious Diseases

“…For RNA, T7 RNA polymerase promoter-containing primers are used in RT-PCR after which RNA libraries are amplified by in vitro transcription. The protocol follows the same amplification steps for several rounds (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) as for DNA SELEX (Figure 1). Negative selection can be included in either RNA or DNA SELEX protocols, which is achieved by passing the nucleic acid pool over a supporting matrix in the absence of the target.…”