STUDY OF AXL ISOFORMS IN BLADDER CANCER CELLS USING CRISPR/CAS9 TECHNOLOGY

Abstract

One of the three receptors of the TAM family, AXL, is associated with the survival of cancer cells, making them resistant to chemotherapeutic drugs (Graham et al., 2014). AXL binding to its ligand Gas6 is important for activation of pathways involved in tumor cell invasion, metastasis, and survival. Therefore, developing AXL/Gas6-targeted anticancer drugs is of great interest (Tanaka & Siemann, 2021). The extracellular fragment of AXL can be proteolytically cleaved by ADAM10 and ADAM17. This results in soluble AXL (sAXL) that can inhibit AXL by binding to its ligand. High sAXL concentration in patient plasma is a tumor biomarker of adverse outcome (Miller et al., 2016). In humans there are only two well established isoforms; isoform 1 containing exon 10 and isoform 2 lacking exon 10. Significantly, the ADAM10/17 cleavage site for sAXL is found at exon 10 of isoform 1. However, sAXL formation leads to activation of signalling pathways that promote cancer metastasis and survival (Shen et al., 2020). The exact mechanism is not known, but it is thought that after receptor shedding, AXL may form heterodimers with non-TAM family receptors, which induces non-canonical pathways in cancer (Malikova et al., 2025). CRISPR/Cas9 technology will be used to study the differences between the two isoforms (such as the lack of cleavage site in isoform 2 and sAXL formation) and the effect of these isoforms on cancer cells. In a bladder cancer cell line it is used to express only isoform 2 by deleting exon 10. Cells expressing sAXL will be observed in the conditioned media. With this study, we will be able to understand how isoforms impact AXL function and how much they impact bladder cancer survival.