Introduction Obesity is strongly associated with oesophageal adenocarcinoma (OAC). However, its role in regulating radiosensitivity and genomic instability is unknown. We developed an isogenic model of radioresistance in OAC called OE33R. We assessed levels of anaphase bridges, a functional genomic instability event, in OE33R compared to an age and passage matched control (OE33P). Spindle assembly checkpoint (SAC) control genes involved in regulating genomic instability were analysed in both cell lines following exposure to adipose conditioned media (ACM). Radiosensitivity following ACM treatment was investigated in OE33R and OE33P cell lines. The aim of this study was to characterise the isogenic radioresistant OAC cell model in terms of genomic instability, SAC gene expression and survival in response to adipose conditioned media (ACM) cultured from obese and nonobese OAC patients.
Methods OE33R and OE33P cell lines were cultured with ACM from obese and nonobese patients. We assessed anaphase bridges in both lines and quantified the number of bridges present over the total cell number. Expression of five SAC genes (MAD2L2, BUB1B, CDC20, CENPE, and ESPL1) was assessed using qPCR. Survival was determined in both cells lines following ACM treatment using a clonogenic assay.
Results OE33P and OE33P showed a significant increase in anaphase bridges in response to ACM (p<0.05, p<0.001 respectively). This increase in anaphase bridge formation was three times greater in the resistant line (p<0.05). Levels of anaphase bridge formation correlated with obesity status (BMI and VFA, p<0.05). OE33R cells treated with ACM showed significantly increased expression of the SAC genes MAD2L2 and BUB1B compared to controls (p<0.01). Expression of MAD2L2 and BUB1B correlated with obesity status (p<0.05). OE33P cells treated with ACM showed increased radioresistance (p<0.05). In contrast, in the resistant OE33R cell line, ACM treatment reversed this radioresistance (p<0.001).
Conclusion Obesity drives genomic instability and alterations in SAC gene expression in radioresistant OAC and alters radiosensitivity in OAC.
Competing interests None declared.