Anti-KIT DNA Aptamer for Targeted Labeling of Gastrointestinal Stromal Tumor

Abstract

Gastrointestinal stromal tumor (GIST), the most common sarcoma, is characterized by KIT protein overexpression, and tumors are frequently driven by oncogenic KIT mutations. Targeted inhibition of KIT revolutionized GIST therapy and ushered in the era of precision medicine for the treatment of solid malignancies. Here, we present the first use of a KIT-specific DNA aptamer for targeted labeling of GIST. We found that an anti-KIT DNA aptamer bound cells in a KIT-dependent manner and was highly specific for GIST cell labeling in vitro. Function-ally, the KIT aptamer bound extracellular KIT in a manner similar to KIT mAb staining, and was trafficked intracellularly in vitro. The KIT aptamer bound dissociated primary human GIST cells in a mutation agnostic manner such that tumors with KIT and PDGFRA mutations were labeled. In addition, the KIT aptamer specifically labeled intact human GIST tissue ex vivo, as well as peritoneal xenografts in mice with high sensitivity. These results represent the first use of an aptamer-based method for targeted detection of GIST in vitro and in vivo.

Hitting the diagnostic sweet spot: Point-of-care SARS-CoV-2 salivary antigen testing with an off-the-shelf glucometer

“…The choice of saliva as a target specimen for testing presents challenges and opportunities. Saliva is the most readily obtained human specimen; however, it is also a complex and viscous sample consisting of various electrolytes, enzymes, and antibodies 38,39 posing hurdles for specific and interference-free biomarker detection 40 . This is reflected in our data, where we found a higher LOD for protein spiked in saliva as compared to buffer, likely a consequence of the viscosity and proteases found in saliva.…”

“…Aptamers are oligonucleotide (DNA or RNA) ligands that are selected through an iterative process known as SELEX 42,43 . They share similar affinity and specificity to monoclonal antibodies, yet can be mass produced at low cost, are stable at ambient temperatures for long-term storage, and can be chemically modified and engineered to produce conformational switches [44][45][46] . Specifically, the amount of overlap between the aptatope and the antisense strand in this assay allows the affinity to be engineered where it is intentionally designed to have low affinity for facile release when the viral protein is present.…”

Development of a Soluble KIT (sKIT) Electrochemical Aptasensor For Cancer Theranostics

“…Selectivity is an important characteristic of any receptor-target-based assay. While the specificity of the KIT aptamer was previously reported (Zhao et al, 2015;Banerjee et al, 2020), it is crucial to verify the specificity with the addition of the Fc reporter and the change to electrochemical rather than optical readout. To investigate the selectivity of the conformation changing aptasensor, voltammograms with various proteins (IL-6, UEA, BSA, Fibrinogen, and HSA) were measured, as shown in Fig.…”

“…Cell culture media and serum assays. KIT is known to be overexpressed in GIST and Mastocytosis (Banerjee S et al 2020). It has been shown that a soluble KIT fragment (sKIT) is released from cell surfaces and can be used for cancer theranostics (Akin et al, 2000;DePrimo et al, 2009;Sarlomo-Rikala et al, 1998).…”

“…Full-length c-KIT and sKIT have been studied as a biomarker with various detection methods including flow cytometry (Banerjee et al, 2020; Naeem et al, 2002), immunohistochemical analysis (Pilloni et al, 2011), and enzyme-linked immunosorbent assay (ELISA) (Tajima et al, 1998). Although these methods provide quantitative information, they suffer disadvantages in terms of requiring sophisticated pretreatment steps, high-cost, large sample volume, expensive laboratory reagents, and sophisticated instruments for the detection process, which is not ideal as a point-of-care system (Lu et al, 2015; Jo et al, 2016).…”