Human AKT1/AKT2 Knockout Cell Line-HCT116

Human tumor growth depends on rapidly dividing cancer cells that drive population expansion. However, even advanced tumors contain slowly proliferating cancer cells for reasons that are unclear. Here, researchers used β1 integrin activation and the AKT1-E17K mutant oncoprotein as in vivo experimental tools to selectively disrupt the ability of rapidly proliferating cancer cells to generate AKT1^low daughter cells, which are rare, slowly proliferating, tumor-initiating, and chemoresistant. Surprisingly, researchers found that selective depletion of AKT1low slow proliferators actually reduced growth in a molecularly diverse panel of human cancer cell xenograft models without globally altering cell proliferation or in vivo survival. Furthermore, an unusual cancer patient with an AKT1-E17K mutant solid tumor also failed to generate AKT1^low quiescent cancer cells, which was associated with significantly prolonged survival after adjuvant therapy compared to other patients. These findings support a model in which human solid tumor growth depends not only on rapidly proliferating cancer cells but also on the continued generation of AKT1^low slow proliferators.

In this study, HCT116-AKT1/2 knockout cells failed to generate quiescent cancer cells (QCCs), but lentiviral-mediated overexpression of cDNA encoding wild-type AKT1 completely restored the generation of these MCM2^low/H3K9me2^low/HES1^high cells in this AKT knockout line (Figure 1). In addition, overexpression of cDNA of myr-AKT1, an artificially mutated kinase-active protein that constitutively localizes to the cell membrane, did not rescue the generation of QCCs in HCT116-AKT1/2 knockout cells compared with wild-type AKT1 (Figure 1).

Figure 1. Bar graph percentages of QCCs in the HCT116-AKT1/2 knockout human cancer cell line with cDNAs for AKT1-WT or AKT1 mutants. (Alves, Cleidson P., et al. 2018)