Genome sequencing efforts have identified PAK7 (p21-activated kinase 7) as a potentially important cancer kinase. PAK7 ranked 17 among all 518 kinases in probability of harboring driver mutations for human cancer. The vast majority of PAK7 mutations in human cancer are missense and thus suggestive of a role as an oncogene. PAK7 mutations occur in a significant proportion of lung and gastrointestinal carcinomas, as well as in malignant melanomas. Our preliminary data suggest that cancer mutations in PAK7 potently stimulate kinase activity. However, PAK7 is a minimally characterized kinase, thus providing merit to address the following aims: (1) Are putative PAK7 driver mutations required for oncogenic capacities in cancer cells? (2) Are putative PAK7 driver mutations sufficient to promote epithelial oncogenesis? We will rigorously address these aims by genome editing to avoid confounding effects associated with exogenous expression or knockdown of genes. First, we will correct PAK7 missense mutations in human cancer cell lines. We will then determine whether correction of these mutations reverts any transformed capacities that these cell lines possess. Specifically, we will assay cell proliferation, apoptosis, invasion, and tumorigenicity inathymic mice. Second, we will introduce putative PAK7 driver mutations into the relatively well-differentiated colonic Caco-2 cells and bronchial 16HBE14o- cells. In addition to the capacities listed above, we will determine effects of PAK7 cancer mutations on parameters of normal epithelial architecture; a hallmark of differentiated epithelial cells with established tumor suppressor capacities. Specifically, we will test whether naturally occurring PAK7 mutations in cancer affect epithelial cell polarity, cell-cell adhesion, and lumen formation in 3D culture. Collectively, the proposed studies will provide a stringent initial approach to define the oncogenic potential of PAK7 mutations in human cancer and elucidate whether PAK7 represents a promising candidate in expanding targets for cancer therapeutics.
