Lysyl-tRNA Synthetase (KRS) Expression in Gastric Carcinoma and Tumor-Associated Inflammation

Lysyl-tRNA synthetase (KRS) is an aminoacyl-tRNA synthetase (ARS) that is essential for protein synthesis during ligation of specific amino acids to their cognate tRNAs. Aberrant expression of ARSs is associated with various human cancers. Using immunohistochemical detection, the present study analyzed the clinical relevance of KRS expression in tumor cells and tumor-associated inflammatory cells (TAI) in 457 patients who underwent curative radical surgery and standard adjuvant therapy and who were observed on long-term follow-up. High expression of KRS in tumor cells (tumor-KRS(+)) was noted in 43.3 % (198 of 457) of cases. High expression of KRS in tumor-associated inflammatory cells (TAI-KRS(+)) including macrophages/monocytes, CD4-positive T cells, and/or neutrophils was observed in 37.2 % (170 of 457) of cases. Status of KRS in the tumor and TAI revealed an association with the known clinicopathological parameters for prognosis of gastric cancer. Tumor-KRS(+) status correlated to shorter overall survival, especially in stage III to IV cancers (P = 0.003), while TAI-KRS(+) status correlated significantly to longer overall survival in gastric cancer (P = 0.049). Cases with tumor-KRS(+) and TAI-KRS(-) status showed significantly reduced survival rates compared to those of other cases (P = 0.010), and status of tumor-KRS(+) and TAI-KRS(-) was revealed as an independently poor prognostic factor of overall survival (P = 0.001). KRS-related inflammation can be identified in a subset of gastric cancer. This may be a possible mechanism of immune surveillance against tumor progression. In addition, expression status of KRS in tumor and TAI may be an independent prognostic marker for gastric cancer patients.