Genetic Disruption of Ki-67 Results in Decreased Clonogenic Proliferation

Ki-67;Knockout;Biology

Cidado, JustinDenmeade, Samuel R. ;

Johns Hopkins University

关键词: Ki-67;    Knockout;    Biology;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/37058/CIDADO-DISSERTATION-2014.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Two well-known hallmarks of cancer are the abilities to sustain proliferation and invade surrounding tissue, and pathways involved in these processes have been scrutinized for possible therapeutic targets in recent years. Since its discovery, Ki-67 has been intimately linked to the cell cycle and widely accepted as a marker for the growing fraction of cells in a tumor sample, and more recently its potential as a prognostic and predictive marker for various cancers has been explored. Despite the wide use of Ki-67 in the clinical and pathological setting, little is known about its actual function and role as a potential therapeutic target for cancer. To better characterize Ki-67’s function to optimally exploit this gene/protein for prognostic, predictive, and therapeutic purposes, we created isogenic Ki-67 knockout cells in a ;;normal” and cancer cell line. Unlike previous efforts to knockdown Ki-67, we were able to generate multiple independent Ki-67 knockout clones in two cell lines that definitively lacked functional full length Ki-67 protein. In colony formation assays in vitro and tumorigenic assays in vivo, the knockout clones displayed a reduced proliferative and clonogenic potential, illustrating how inhibition of Ki-67 could result in a decreased ability of cancer cells to invade and colonize surrounding and distant tissue. A current model of metastasis maintains that cancer stem cells (CSCs) are required to establish tumor formation at distant sites, and in colorectal cancers, those CSCs are often identified by the expression of cell surface markers CD133 and CD44. The knockout clones had a markedly reduced CD133+CD44+ population of cells compared to the parental cell line, demonstrating that loss of Ki-67 resulted in fewer colonies and tumors by decreasing the ;;stemness” of the cells. CSCs are known to be resistant to various chemotherapies, but we found that the loss of Ki-67 in the cancer cell line resulted in sensitization to multiple chemotherapeutic agents. These findings combine to establish that Ki-67 is a viable therapeutic target, particularly in the metastatic setting. By specifically inhibiting Ki-67, it could be possible to greatly decrease the risk of micrometastatic disease that is often times refractory to standard therapy.