Abstract
Purpose :
To examine the effects of mitogen activated protein kinase inhibitor (MEKi) treatment on EGR1 expression in BRAF mutant and wild type melanoma in cell culture.
Methods :
We used three cell lines to investigate the response of EGR1, a transcription factor, to MEK inhibition. Two cell lines were derived from cutaneous melanoma, MEL888 and MEL624, and harbored the same BRAF mutant, Val600Glu (V600E). YUARGE 13-3064 was generated from a conjunctival melanoma neck lymph node metastasis and was BRAF wild type. After plating and overnight incubation, cells were treated daily for 72 hours with the MEK inhibitor trametinib at 18 nM concentration compared to DMSO vehicle control. At 72 hours, viability was measured using PrestoBlue™. qPCR and simple western assays were used to evaluate changes in EGR1 expression and a panel of genes associated with EGR1 and the MEK pathway. Targeted knockdown of EGR1 was performed to determine whether the observations in the MEK treated cells were a direct result of EGR1 knockdown.
Results :
In MEL888, MEL624, and YUARGE 13-3064, treatment with the MEKi trametinib reduced viability and resulted in reduced EGR1 expression at the RNA (p<0.001, p<0.001, and p=0.04, respectively) and protein level (p=0.03, p=0.03, and p=0.007, respectively). Targeted EGR1 knockdown resulted in similar reduction in viability for BRAF mutant melanoma MEL888 compared with trametinib treatment.
Conclusions :
MEKi treatment of BRAF mutant and BRAF wild type melanoma resulted in knockdown of EGR1 gene and protein expression in cell culture. Direct EGR1 knockdown resulted in reduced viability for BRAF mutant melanoma, suggesting a key role for EGR1 in the anti-cancer effects of MEKi for melanoma treatment.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.