Expression of stem cell markers nanog and PSCA in gastric cancer and its significance.

The present study aimed to determine the expression of stem cell markers Nanog compared with PSCA in gastric cancer tissues and adjacent normal tissues, and to investigate the association between tumor stem cells and initiation, progression, metastasis, and prognosis of gastric cancer. One hundred chemotherapy- and radiotherapy-naive patients with pathologically confirmed gastric cancer were enrolled from the General Surgery Department and Surgical Oncology Department of the Affiliated Hospital of Inner Mongolia Medical University (Hohhot, P.R. China), between October 2011 and June 2013. Surgically resected specimens of cancer tissues and adjacent normal tissues (>5 cm from the boundary of cancerous component) were collected. The mRNA expression levels of Nanog and PSCA in those tissues was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The correlation between the expression of stem cell markers Nanog and PSCA in gastric cancer tissues and clinicopathological factors was analyzed. The qPCR results demonstrated that the relative expression of Nanog was increased in gastric cancer tissues compared with in the adjacent tissues (P<0.05); and relative expression of PSCA was reduced in gastric cancer tissues compared with adjacent tissues (P<0.05). The expression of Nanog and PSCA in gastric cancer tissues was associated with tumor differentiation. The expression of Nanog was increased in poorly-differentiated and undifferentiated tumors compared with moderately- and well-differentiated tumors (P<0.05). The expression of PSCA was reduced in poorly differentiated and undifferentiated tumors compared with moderately- and well-differentiated tumors (P<0.05). However, the expression of Nanog and PSCA was not associated with age, gender, tumor size, TNM stage, depth of invasion, or lymph node metastasis. Therefore, Nanog and PSCA may have potential as molecular markers to reflect the differentiation status of gastric cancer.