Abstract
BackgroundTumorigenesis is the result of genomic or epigenomic insults and subsequent loss of the proper mechanisms to respond to these alterations leading to unscheduled growth. Tumors arising from these mutations often have altered cell cycles that offer proliferative advantages and lead to the accumulation of additional mutations that can lead to more aggressive phenotypes. Nevertheless, tumor cells must still adhere to the basic tenets of the cell cycle program to ensure their survival by DNA duplication, chromosomal segregation and cytokinesis. The atypical tyrosine kinase Wee1 plays a key role in regulating the cell cycle at the DNA synthesis and mitotic checkpoints via phosphorylation and subsequent inactivation of cyclin-dependent kinases (CDKs) in both healthy and tumorigenic cells.MethodsTo assess the role of Wee1 in tumor cell proliferation we performed small interfering RNA (siRNA) experiments in a panel of diverse cell lines derived from various tissue origins. We also tested the hypothesis that any potential effects would be as a result of the kinase activity of Wee1 by siRNA rescue studies with wild-type or kinase-dead versions of Wee1.ResultsWe find that, in general, cells with wild-type p53 activity are not susceptible to loss of Wee1 protein via siRNA. However, Wee1 siRNA treatment in tumor cells with an inherent loss of p53 activity results in a deregulated cell cycle that causes simultaneous DNA synthesis and premature mitosis and that these effects are kinase dependent. These cumulative effects lead to potent inhibition of cellular proliferation and ultimately caspase-dependent apoptosis in the absence of co-treatment with cytotoxic agents.ConclusionsThese results suggest that, while Wee1 acts as a tumor suppressor in the context of normal cell growth and its functional loss can be compensated by p53-dependent DNA damage repairing mechanisms, specific inhibition of Wee1 has deleterious effects on the proliferation and survival of p53 inactive tumors. In total, targeting the atypical kinase Wee1 with an siRNA-based therapeutic or a selective ATP competitive small molecule inhibitor would be a feasible approach to targeting p53 inactive tumors in the clinic.
Highlights
Tumorigenesis is the result of genomic or epigenomic insults and subsequent loss of the proper mechanisms to respond to these alterations leading to unscheduled growth
We find that loss of Wee1 kinase activity results in dramatic cell cycle events including simultaneous mitosis and DNA synthesis that lead to apoptosis in a sub-set of p53 deficient cells
The resulting phenotypes of Wee1 small interfering RNA (siRNA) resulted in dramatic inhibition of cellular proliferation as measured by MTS reagent in H1299 non-small cell lung (NSCLC) and Daoy glioma cell lines but did not affect growth of A549 Non-small cell lung (NSCLC), D54MG glioma or A2780 ovarian tumor lines (Figure 1)
Summary
Tumorigenesis is the result of genomic or epigenomic insults and subsequent loss of the proper mechanisms to respond to these alterations leading to unscheduled growth Tumors arising from these mutations often have altered cell cycles that offer proliferative advantages and lead to the accumulation of additional mutations that can lead to more aggressive phenotypes. Progression through the cell cycle in both naïve and tumor tissue is monitored at checkpoints that sense possible defects in DNA synthesis and chromosomal segregation. Activation of these checkpoints results in cell cycle arrest and allows cells to rectify any negative perturbations that may be transmitted to their resulting daughter cells. Deregulation of cell cycle control can have catastrophic results and has led to a concerted effort towards generation of novel therapeutic agents targeting the cell cycle in tumors [1]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
