OBJECTIVETo explore the expression of KIF18A gene protein in gastric cancer tissues and its association with the prognosis of patients.

METHODSTwenty fresh paired gastric cancer specimens and adjacent normal mucosa(at least 5 cm from the edge of tumor) from 20 gastric cancer patients undergoing operation in Department of General Surgery at the First Affiliated Hosptial of Anhui Medical University between March 2015 and July 2015 were collected. Real-time PCR was used to examine KIF18A mRNA expression in above specimens. Meanwhile, paraffin embedded cancer tissue samples from 129 gastric cancer patients undergoing operation and 23 samples of randomly selected normal gastric tissue(adjacent non-cancer tissue) were collected to establish the microarray. Immunohistochemistry method was applied to detect the KIF18A protein expression in the microarray after confirmation by pathologists. Association of KIF18A expression with clinicopathological features in gastric cancer patients was evaluated. Cox proportional hazard model was used to identify prognostic risk factors.

RESULTSAmong 20 fresh paired gastric cancer specimens, mRNA expression of KIF18A in 16 specimens was obviously lower than that in adjacent normal tissues. The positive rate of KIF18A protein expression in gastric cancer tissues was significantly lower than that in normal gastric tissues in microarray[45.0%(58/129) vs. 69.6%(16/23), P=0.041]. KIF18A protein expression was significantly associated with invasion depth (P=0.008) and TNM staging (P=0.032). The median overall survival of all the 129 patients was 44.0(95% CI: 39.78-49.24) months. The three-year survival rates of patients with high and low KIF18A expression were 67.2% and 36.6% respectively(P=0.020). Cox regression analysis showed that KIF18A expression was an independent protective factor of the prognosis of gastric cancer patients (HR=0.570, 95% CI:0.335 to 0.970).

CONCLUSIONSKIF18A expression is down-regulated in gastric cancer tissue, which may play a critical role in gastric cancer carcinogenesis. Lower expression of KIF18A is associated with poor prognosis of gastric cancer patients. KIF18A may be a potential prognostic marker of gastric cancer.