Cancer stem cell marker in circulating tumor cells: expression of CD44 variant exon 9 is strongly correlated to treatment refractoriness, recurrence and prognosis of human colorectal cancer.

Abstract

BACKGROUND/AIM: The expression of the CD44 variant exon 9 (CD44v9) was investigated in order to elucidate its significance for cancer stem cells in circulating human colorectal cancer cells (CTCs). MATERIALS AND METHODS: After peripheral blood was drawn from patients with colorectal cancer, CTCs were collected. Using the reverse transcription-polymerase chain reaction method, we examined the relationship between expression of CD44v9 mRNA and prognosis. RESULTS: In 60 out of 150 patients with colorectal cancer, expression of CD44v9 mRNA was positive in CTCs. In patients with stage III disease, the 5-year survival rate was 89% for patients with negative CD44v9 expression, whereas it was 52.4% in patients with positive expression (p<0.05). In patients with stage IV unresectable cancer, the 2-year survival rate was 70.1% in cases with CD44v9-negative expression and 33.3% in cases of positive expression (p<0.05). CONCLUSION: CD44v9 mRNA in the CTCs of colorectal cancer is useful as a factor predicting recurrence, prognosis, and treatment efficacy.