Detection of Kita-Kyushu Lung Cancer Antigen-1, a Cancer/Testis Antigen, in the Stomach Close to a Cancerous Condition

Abstract

Background: Kita-Kyushu lung cancer antigen-1 (KK-LC-1), encoded by CT83, is a cancer/testis antigen (CTA) and an attractive target for immunotherapy. Our previous study demonstrated frequent CT83 expression in gastric cancers (GCs) and non-tumor sites of the stomach with tumors. Additionally, there was a correlation with Helicobacter pylori (Hp) infection. Since it currently remains unclear whether KK-LC-1 is expressed in the stomach without GC, this study investigated KK-LC-1 expression in non-GC stomach. Methods: We investigated differences in CT83 gene expression at non-tumor sites of stomachs with or without tumors in 118 GC patients and 115 non-GC patients. Fisher's exact test was used for statistical analyses. Results: CT83 expression was detected in 77% of non-tumor sites in stomachs with tumors, which was significantly higher than in stomachs without tumors (7%, p < 0.0001). All patients with CT83 expression at non-tumor sites of their stomachs without tumors carried Hp. Conclusion: CT83 appears to be rarely expressed in the atrophic stomach, and furthermore, a part of patients positive for its expression will develop GC in the future, suggesting that CT83 expression is a useful marker for predicting GC.

Keywords: Helicobacter pylori; Kita-Kyushu lung cancer antigen-1; atrophic gastritis; gastric cancer.

Figure 1

Representative panel of CT83 expression in noncancerous gastric specimens. CT83 expression was detected as an amplicon band of 342 bp. CT83 expression was detected in 1 of 12 stomach samples (lane No. 5). Bands between 1000 and 1500 indicate amplicons of genomic DNA of CT83. M, 100 bp ladder; P, positive control (cDNA of MKN45 cell line); N, negative control.

Figure 2

Expression rate of CT83 during the transition to gastric abnormality. The expression rate of CT83 is summarized for each stage of gastric abnormality. CT83 was not expressed in the stomach under normal conditions. However, with the development and progression of gastric abnormality, CT83 expression was increased in the following order: atrophic gastritis without and with Hp infection, non-tumor sites of the precancerous stomach with gastric cancer, and early and advanced gastric cancer tumors. This study showed that CT83 expression was clearly discrepant between non-cancerous and cancerous stomachs regardless of Hp infection. The CT83 expression rate in malignancy including early and progressive stages was adopted from Futawatari et al. . Hp, Helicobacter pylori.