Effects of miR-34a Promoter Regulation on PD-L1 Expression in Lung Cancer Cell Lines

Brooke Brothers,* Alyson Stevens* and Ivan Martinez, WVU Cancer Institute, West Virginia University, Morgantown, WV 26506

Field (Broad Category): Medical Sciences (Health Sciences) 

Student’s Major: Immunology and Medical Microbiology 

PD-L1 is a protein found in the membranes of antigen presenting cells that binds its receptor PD-1 on T cells, resulting in the suppression of an immune response. Cancer cells express high quantities of PD-L1 to evade immune system detection and allow tumor proliferation. PD-L1 synthesis can be inhibited posttranscriptionally by miR-34a, a microRNA regulated by tumor suppressor p53. Preliminary research was performed by treating male and female non-small cell lung cancer (NSCLC) cell lines with radiotherapy and analyzing gene expression of PD-L1 and miR-34a post radiation. Results suggested females had higher expression of PD-L1 and lower or plateaued expression of miR-34a after radiation. In contrast, males had lower or plateaued expression of PD-L1 and higher expression of miR-34a after radiation. Cell lines studied were a mix of wild type and mutated p53, suggesting potential p53 independent miR-34a regulation. This study builds upon previous data by examining the promoter region of miR-34a mRNA through transfection of a luciferase reporter plasmid into male and female NSCLC cell lines, followed by analysis of luciferase expression. Additional studies will be performed to measure miR-34a promoter methylation differences between male and female NSCLC cell lines. Previous publications establish the capability of the miR-34a promoter to be methylated, but no previous research has considered a difference in methylation between sexes and how that could affect PD-L1 expression. This project’s findings aid in further progression of understanding how cancer therapies, such as targeted PD-L1 immunotherapy, could potentially have sexdependent efficacies. 

Funding: NAH 

Program/mechanism supporting research/creative efforts: WVU's Research Apprenticeship Program (RAP) & accompanying HONR 297-level course