Ovarian Cancer‐Associated Ascites Accumulates NK Lymphocytes Displaying a Transcriptomic Profile Consistent With the Immature/Secretory CD56 bright Subtype

ABSTRACT Natural killer (NK) cells are important lymphocytes of the innate immune response against cancer. Based on their molecular and functional phenotypes, NK cells are categorized into two main subtypes known as CD56 dim and CD56 bright , which display distinct transcriptional profiles. Additionally, transcriptomic alterations may arise in response to different stimuli or microenvironmental conditions, ultimately affecting NK‐cell functions. Here, RNA sequencing (RNAseq) was performed to characterize the transcriptomic profile of NK cells from epithelial ovarian cancer (EOC)‐associated ascites. Two bulk RNAseq datasets were analyzed: one generated from samples collected from patients assisted at the Women's Hospital of the University of Campinas (CAISM‐Unicamp, Brazil) and a second publicly available dataset obtained from the Gene Expression Omnibus database (GSE153713). Our transcriptomic analysis identified 5427 differentially expressed genes (DEGs; adjusted p < 0.05), revealing extensive differences between ascites and blood NK cells. Furthermore, these findings indicated a possible shift in the biological program of ascites NK cells, from the conventional cytotoxic CD16 + CD56 dim subtype to an immature/secretory CD56 bright profile. Comparison of ascites and blood NK RNAseq based on a previously defined transcriptional framework showed reduced NK1 and increased NK2 subtype scores in ascites, confirming association with distinct biological programs. In conclusion, ascites NK cells retain elements of the conventional NK‐cell program while displaying a transcriptional profile distinct from peripheral blood NK cells, consistent with transcriptional remodeling to biological programs usually associated with the CD56 bright NK subtype.