Generation and initial characterisation of parental and A3A-knockout bladder cancer cell line clones for cancer drug resistance studies

The primary role of the APOBEC3 family of enzymes is within the innate immune system, acting to limit the infectivity of retroviruses through the deamination of their DNA intermediates by converting DNA cytosines to uracils, leaving behind a series of characteristic mutational signatures. However, over the years since the initial discovery of this family of enzymes and their roles, a series of landmark papers have been published that reveal the presence of these same signatures in a wide variety of human cancers, with APOBEC ranking as the second most commonly seen endogenous mutational signature across all human cancers. This discovery prompted investigations into the underlying mechanisms behind this and into the member of the APOBEC family most likely to be causing these endogenous mutations and its possible interactions with common chemotherapeutics, however results remain unclear and contentious with various studies by high-level labs and authors disagreeing and debunking one another. This study aimed to investigate the effect that A3A may have on the pace of development of resistance to cis-platin in BFTC-905 bladder cancer cells. This was due to be completed by using single cell culture and transfection techniques to expand numbers of colonies of A3A KO BFTC-905 cells that were created by a previous MSc-R student using CRISPR-Cas9, followed by a series of MTT assays and drug-sensitisation protocols on these A3A KO cells compared to their BFTC-905 WT equivalents. We were able to expand on the numbers of both the A3A KO and WT BFTC-905 cells and verify their A3A status using qPCR but were unable to perform the MTT and drug-sensitisation due to COVID-19 and the resultant lockdown period.