Evolution of the AGMK1-9T7 GLI1+ progenitor cells to become tumor cells and potentially cancer-stem cells

Abstract

We have investigated the expression of selected genes and miRNAs that have been found to be associated with human cancer-stem cells for their involvement in the neoplastic evolution of our AGMK1-9T7 cell line from a non-tumorigenic status at passage (p)13 to a tumorigenic/metastatic status at p40 to p43. Among these genes are CD90, CD44, CD24, PODXL, ALDH1A, ALDHA2, and ALDHA3 genes, as well as 17 other genes and 38 miRNAs. While CD90 and CD24 were not expressed by any passages of AGMK1-9T7 cells, CD44 was expressed in cells at p13, p23, p33, and p43. The expression of PODXL was first detected as weakly expressed at p33 but was highly expressed by p43. Of the 17 genes that have been associated with human cancer-stem-cell functions that we examined across this spectrum of neoplasia, 5 were up-regulated >2 log2 fold and 8 were down-regulated >2 log2 fold. The expression of the ALDH1A genes, which have been associated with cancer-stem cells, was investigated by the ALDEFLUOR assay in AGMK1-9T7 cells from p13 to p43. Using RT-qPCR, the ALDH1A2 gene was found to be up-regulated in cells from p13 to p43. Twenty-six of the 38 miRNAs reported to be associated with human cancer-stem cells were expressed by the AGMK1-9T7 cells at different passages. From these data, we propose that the AGMK1-9T7 cells are evolving from their non-tumorigenic state to become tumor cells and potentially cancer-stem cells by p43. We suggest that this in vitro system might provide a model to investigate the role of these processes in neoplastic development in humans.