Purpose: Paired related homoeobox 1 (PRRX1) has been identified as a new epithelial-mesenchymal transition (EMT) inducer in gastric cancer and that PRRX1 upregulation is closely correlated with gastric cancer metastasis. In addition, circulating tumor cells (CTCs) play an important role in the process of gastric cancer's distant metastasis. Our study aimed to correlate Prrx1, CTCs and the clinicopathological parameters in primary gastric cancer patients.
Methods: Expressions of PRRX1 in a sample of 95 gastric carcinoma and adjacent nontumorous tissues were detected by immunohistochemistry. Then the integrated subtraction enrichment and immunostaining fluorescence in situ hybridization (SET-imFISH) platform were applied to detect and characterize CTCs in patients with gastric cancer. Finally, their correlations with clinicopathological parameters could be analyzed.
Results: The positive rate of PRRX1in gastric cancer was 56.84% and the rate was 36.84% in adjacent normal gastric mucosa, which was confirmed to be statistically significant. In the meantime, both the expression of PRRX1 and the positive rate of CTCs did not significantly correlate with age, gender or histologic type (p>0.05) but significantly related to tumor size, grade of differentiation, lymph node invasion, vascular invasion, metastasis status, depth of tumor invasion, lymph node metastasis and TNM stage (p<0.05). Besides, there was a close relationship between the PRRX1 of gastric cancer and the CTCs of peripheral blood specimens of cancer patients with the correlation coefficient 0.322.
Conclusion: Gastric cancer tissues showed that the level of PRRX1 expression was higher compared to the adjacent normal gastric mucosa. Both the expression of PRRX1 and the positive rate of CTCs significantly correlated with clinicopathological parameters. In addition, there was a positive correlation relationship between the PRRX1 of gastric cancer and the CTCs of peripheral blood specimens of cancer patients. These findings demonstrate that higher-level expression of PRRX1 in gastric cancer tissues increased the amount of CTCs in peripheral blood and facilitated the invasion and metastasis in patients with gastric cancer. Meanwhile, it gave some clues to clinical treatment. CTCs may contribute to promotion in diagnosis, therapy monitoring and prognosis of gastric cancer.