The spindle assembly checkpoint (SAC) is essential for proper sister chromatid segregation. Defects in this checkpoint can lead to chromosome missegregation and aneuploidy. An increasing body of evidence suggests that aneuploidy can play a causal role in tumorigenesis. However, mutant mice that are prone to aneuploidy have only mild tumor phenotypes, suggesting that there are limiting factors in the aneuploidy-induced tumorigenesis. Here we provide evidence that p53 is such a limiting factor. We show that aneuploidy activates p53 and that loss of p53 drastically accelerates tumor development in two independent aneuploidy models. The p53 activation depends on the ataxia-telangiectasia mutated (ATM) gene product and increased levels of reactive oxygen species. Thus, the ATM-p53 pathway safeguards not only DNA damage but also aneuploidy.
FTO (fat mass and obesity associated) was identified as an obesity-susceptibility gene by several independent large-scale genome association studies. A cluster of SNPs (single nucleotide polymorphism) located in the first intron of FTO was found to be significantly associated with obesity-related traits, such as body mass index, hip circumference, and body weight. FTO encodes a protein with a novel C-terminal α-helical domain and an N-terminal double-strand β-helix domain which is conserved in Fe(II) and 2-oxoglutarate-dependent oxygenase family. In vitro, FTO protein can demethylate single-stranded DNA or RNA with a preference for 3-methylthymine or 3-methyluracil. Its physiological substrates and function, however, remain to be defined. Here we report the generation and analysis of mice carrying a conditional deletion allele of Fto. Our results demonstrate that Fto plays an essential role in postnatal growth. The mice lacking Fto completely display immediate postnatal growth retardation with shorter body length, lower body weight, and lower bone mineral density than control mice, but their body compositions are relatively normal. Consistent with the growth retardation, the Fto mutant mice have reduced serum levels of IGF-1. Moreover, despite the ubiquitous expression of Fto, its specific deletion in the nervous system results in similar phenotypes as the whole body deletion, indicating that Fto functions in the central nerve system to regulate postnatal growth.
Glioblastoma multiforme (GBM) is the most malignant and aggressive type of brain tumor with an average life expectancy of less than 15 months. This is mostly due to the highly mutated genome of GBM, which is characterized by the deregulation of many key signaling pathways involving growth, proliferation, survival, and apoptosis. It is critical to explore novel diagnostic and therapeutic strategies that target these pathways to improve the treatment of malignant glioma in the future. This review summarizes the most common and important pathways that are highly mutated or deregulated in GBM and discusses potential therapeutic strategies targeting these pathways.
The anaphase promoting complex (APC) or cyclosome is a multi-subunit E3 ubiquitin ligase. Cdc20 [fizzy (fzy), or p55CDC] and Cdh1 [Hct1, srw1, or fizzy-related 1 (fzr1)] encode two adaptor proteins that bring substrates to APC. Both APC-Cdc20 and APC-Cdh1 are implicated in the control of mitosis through mediating ubiquitination of mitotic regulators such as cyclin B1 and securin. However, the importance of the function of Cdh1 in vivo and whether its function is redundant with that of Cdc20 are unclear. We report here the analysis of mice lacking Cdh1. We show that Cdh1 is essential for placenta development and its deficiency causes early lethality. Cdh1-deficient mouse embryonic fibroblasts entered replicative senescence prematurely due to stabilization of Ets2 and subsequent activation of p16Ink4a expression. These results uncovered an unexpected role of APC in maintaining replicative life span of murine embryonic fibroblasts. Further, Cdh1 heterozygous mice display defects in late-phase long-term potentiation (L-LTP) in the hippocampus and are deficient in contextual fear conditioning, suggesting a role of Cdh1 in learning and memory.
The deep and inner beds of solid tumors lack lymphocytic infiltration and are subjected to various immune escape mechanisms. Reversing immunosuppression deep within the tumor is vital in clinical cancer therapy, however it remains a huge challenge. In this work, we have demonstrated the use of a second window nearinfrared (NIR(II)) photothermal treatment to trigger more homogeneous and deeper immunogenic cancer cell death in solid tumors, thereby eliciting both innate and adaptive immune responses for tumor control and metastasis prevention. Specifically, photothermal transducers with similar components, structures, and photothermal conversion efficiencies, but different absorptions in red light, NIR(I), and NIR(II) biowindows, were constructed by controlling the selfassembly of gold nanoparticles on fluidic liposomes. In vitro, photothermal treatments induced immunogenic cell death (ICD) that were accompanied by the release of damage-associated molecular patterns (DAMPs) regardless of the wavelength of incident lasers. In vivo, NIR(II) light resulted in a more homogeneous release and distribution of DAMPs in the deeper parts of the tumors. With the induction of ICD, NIR(II) photothermal therapy simultaneously triggered both innate and adaptive immune responses and enabled efficient tumor control with 5/8 of the mice remaining tumor-free in the cancer vaccination assay. Additionally, the NIR(II) photothermal treatment in combination with checkpoint blockade therapy exerted long-term tumor control over both primary and distant tumors. Finally, using systemically administered twodimensional polypyrrole nanosheets as a NIR(II) transducer, we achieved striking therapeutic effects against whole-body tumor metastasis via a synergistic photothermal-immunological response.
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