Abstract
Purpose :
Up to 50% of patients with uveal melanoma will develop metastatic disease, and novel treatments are needed to improve survival. We performed cell culture studies to determine the impact of early growth response-1 (EGR1) expression on uveal melanoma (UM) viability and treatment resistance against MEK inhibitors.
Methods :
MP46 primary UM cells were maintained in RPMI media. EGR1 knockdown was accomplished using a lentiviral vector with shRNA against EGR1, and trametinib was used for MEK inhibition. Viability was assessed using an ATP assay, with quantitative real-time PCR and capillary western for gene and protein expression analysis, respectively.
Results :
Treatment with trametinib or direct EGR1 knockdown alone reduced UM viability to 75% and 73%, respectively, compared to DMSO control. Combining trametinib and EGR1 knockdown further reduced viability to 50% (Figure 1) with in an approximate 2.5-fold reduction in EGR1 gene expression (n=3, p=0.01) and undetectable EGR1 protein expression compared to scramble plus DMSO control. Associated gene expression changes included upregulation of the metastasis suppressor NDGR1 and upregulation of COL11A1 and COX6A2, two of the top twenty genes downregulated in metastasis-developing uveal melanoma according to a subanalysis of The Cancer Genome Atlas (TCGA) consortium data.
Conclusions :
Knockdown of EGR1 reduces viability and overcomes resistance to MEK inhibition in UM cell culture, implicating EGR1 as a key effector molecule in UM survival.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.