The cancer stem cell hypothesis states that the capacity of a cancer to grow and propagate is dependent on a small subset of cells. To determine the significances of the cancer stem cell markers CD133, CD44, and CD24 using a comparative analysis with a focus on tumorigenicity.
Four pancreatic cancer cell lines, Capan-1, Mia-PACA-2, Panc-1, and SNU-410 were analyzed for the expressions of CD133, CD44, and CD24 by flow cytometry. The tumorigenicity was compared using tumor volumes and numbers of tumors formed/numbers of injection in nonobese diabetic severe combined deficiency mice. Fluorescence-activated cell sorting (FACS) analysis was used to confirm that xenograft explants originated from human pancreatic cancer cells.
CD133 was positive in only Capan-1, CD44 positive in all, CD24 partially positive in
Panc-1. After injecting 2 × 106 cells, all mice administered Capan-1 or Mia-Paca-2 developed tumors, 3 of 5 administered
Panc-1 developed tumors, but no mouse administered SNU-410 developed any tumors. The volumes of Capan-1 tumors
were seven times larger than those of Mia-Paca-2 tumors. When 2 × 105 or 2 × 104 of Capan-1 or Mia-Paca-2 was injected, tumors
developed in all Capan-1 treated mice, but not in Mia-Paca-2 treated mice. Furthermore, xenograft explants of Capan-1
expressed CD133+CD44+ and Capan-1 injected mice developed lung metastasis. FACS analysis showed that xenograft explants
originated from human pancreatic cancer cell lines.
CD133 positive cells have higher tumorigenic and
metastatic potential than CD44 and CD24 positive cells, which suggests that CD133 might be a meaningful cell surface marker
of pancreatic cancer stem cells.