Yonsei Med J.  2021 Apr;62(4):288-297. 10.3349/ymj.2021.62.4.288.

Clinical Impact of Natural Killer Group 2D Receptor Expression and That of Its Ligand in Ovarian Carcinomas: A Retrospective Study

• Lee GH
• An HJ
• Kim TH
• Kim G
• Park KS
• Park H
• Lee TH
• Kwon AY

• KMID: 2514094
• DOI: http://doi.org/10.3349/ymj.2021.62.4.288

Abstract

Purpose
Natural killer (NK) cells are innate immune cells with antitumor activity. NKG2D is the most important activating receptor expressed on the NK cell surface; this receptor binds to the ligands MICA/B and ULBPs to activate NK cells. The current study aimed to evaluate the expression of NKG2D by NK cells, and to the evaluate expression of its ligands in ovarian carcinomas; it also examined the clinical relevance of NK receptor/ligand expression by analyzing the relationship between expression, clinicopathological parameters, and prognosis.
Materials and Methods
Formalin-fixed paraffin-embedded archival ovarian high-grade serous carcinoma (HGSC, n=79) tissue samples were used for tissue microarray analysis. The expressions of NK cell markers (CD56 and NKG2D) and NKG2D ligands (MICA/B, ULBP1, ULBP3, and ULBP2/5/6) in carcinoma tissues were evaluated by immunohistochemical staining, and the association between these results and clinical prognostic parameters was analyzed statistically.
Results
ULBP1 was highly expressed in 51 cases (64.6%), and ULBP2/5/6 was highly expressed in 56 cases (70.9%) of HGSC. High expression of ULBP1 and ULBP2/5/6 was significantly associated with lower recurrence of HGSC, whereas high expression of ULBP3 was significantly associated with higher recurrence. Multivariate Cox regression analysis revealed that high expression of ULBP1 was associated with increased overall survival and a decreased hazard ratio (0.150, p=0.044), suggesting that it is an independent predictor of better survival.
Conclusion
High expression of ULBP1 predicts a better prognosis for HGSC, suggesting that ULBP1 expression could be a novel prognostic indicator in this subset of carcinomas.

Keyword

NK cell; ovarian carcinoma; NKG2D; NKG2D ligands; ULBP1