Early gastric cancer frequently has high expression of KKLC-1, a cancer-testis antigen

AIM To assess cancer-testis antigens(CTAs) expression in gastric cancer patients and examined their associations with clinicopathological factors.METHODS Eighty-three gastric cancer patients were evaluated in this study. Gastric cancer specimens were evaluated for the gene expression of CTAs, Kitakyushu lung cancer antigen-1(KK-LC-1), melanoma antigen(MAGE)-A1, MAGE-A3 and New York esophageal cancer-1(NYESO-1), by reverse transcription PCR. Clinicopathological background information, such as gender, age, tumor size, macroscopic type, tumor histology, depth of invasion, lymph node metastasis, lymphatic invasion, venous invasion, and pathological stage, was obtained. Statistical comparisons between the expression of each CTA and each clinicopathological background were performed using the χ2 test. RESULTS The expression rates of KK-LC-1, MAGE-A1, MAGE-A3, and NY-ESO-1 were 79.5%, 32.5%, 39.8%, and 15.7%, respectively. In early stage gastric cancer specimens, the expression of KK-LC-1 was 79.4%, which is comparable to the 79.6% observed in advanced stage specimens. The expression of KK-LC-1 was not significantly associated with clinicopathological factors, while there were considerable differences in the expression rates of MAGE-A1 and MAGE-A3 with vs without lymphatic invasion(MAGE-A1, 39.3% vs 13.6%, P = 0.034; MAGE-A3, 47.5% vs 18.2%, P = 0.022) and/or vascular invasion(MAGE-A1, 41.5% vs 16.7%, P = 0.028; MAGE-A3, 49.1% vs 23.3%, P = 0.035) and, particularly, MAGE-A3, in patients with early vs advanced stage(36.5% vs 49.0%, P = 0.044), respectively. Patients expressing MAGE-A3 and NYESO-1 were older than those not expressing MAGE-A3 and NY-ESO-1(MAGE-A3, 73.7 ± 7.1 vs 67.4 ± 12.3, P = 0.009; NY-ESO-1, 75.5 ± 7.2 vs 68.8 ± 11.2, P = 0.042). CONCLUSION The KK-LC-1 expression rate was high even in patients with stage I cancer, suggesting that KK-LC-1 is a useful biomarker for early diagnosis of gastric cancer.

Cancer/testis antigen, Kita-Kyushu lung cancer antigen-1 and ABCD stratification for diagnosing gastric cancers

BACKGROUND The ABCD stratification[combination of serum pepsinogen(PG)levels and titers of antibody(immunoglobulin G,IgG)against Helicobacter pylori(H.pylori)]is effective for the classification of individuals at risk of developing gastric cancer(GC).The Kita–Kyushu lung cancer antigen-1(KK-LC-1)is a Cancer/Testis antigen frequently expressed in GC.AIM To evaluate the effectiveness of KK-LC-1 and ABCD stratification in the diagnosis of GC.METHODS We analyzed the gene expression of KK-LC-1 in surgical specimens obtained from GC tumors.The levels of serum PG I/PG II and IgG against H.pylori were measured.According to their serological status,the patients were classified into the four groups of the ABCD stratification.RESULTS Of the 77 examined patients,63(81.8%)expressed KK-LC-1.The IgG titers of H.pylori and PG II were significantly higher in patients expressing KK-LC-1 than those measured in patients not expressing KK-LC-1(P=0.0289 and P=0.0041,respectively).The expression of KK-LC-1 in group C[PG method(+)/H.pylori infection(+)]was as high as 93.9%high.KK-LC-1 was also detected in group A[-/-].CONCLUSION The KK-LC-1 expression in GC was associated with H.pylori infection and atrophic status,so that,KK-LC-1 may be a useful marker for the diagnosis of GC.