Enhancing oncogenic signaling to kill cancer cells.

Cancer-targeted therapies that inhibit oncogenic signaling often lead to resistance and recurrence. In a recent study, Dias et al. propose activating oncogenic pathways and inducing replication stress, resulting in cell death and tumor-suppressive mechanisms in colorectal cancer (CRC).

ERK pathway agonism for cancer therapy: evidence, insights, and a target discovery framework.

At least 40% of human cancers are associated with aberrant ERK pathway activity (ERKp). Inhibitors targeting various effectors within the ERKp have been developed and explored for over two decades. Conversely, a substantial body of evidence suggests that both normal human cells and, notably to a greater extent, cancer cells exhibit susceptibility to hyperactivation of ERKp.

Influence of SHS Precursor Composition on the Properties of Yttria Powders and Optical Ceramics.

This study looked at optimizing the composition of precursors for yttria nanopowder glycine-nitrate self-propagating high-temperature synthesis (SHS). Based on thermodynamic studies, six different precursor compositions were selected, including with excesses of either oxidant or fuel. The powders from the precursors of all selected compositions were highly dispersed and had specific surface areas ranging from 22 to 57 m/g.

Monitoring autochthonous lung tumors induced by somatic CRISPR gene editing in mice using a secreted luciferase.

Background: In vivo gene editing of somatic cells with CRISPR nucleases has facilitated the generation of autochthonous mouse tumors, which are initiated by genetic alterations relevant to the human disease and progress along a natural timeline as in patients. However, the long and variable, orthotopic tumor growth in inner organs requires sophisticated, time-consuming and resource-intensive imaging for longitudinal disease monitoring and impedes the use of autochthonous tumor models for preclinical studies.

Methods: To facilitate a more widespread use, we have generated a reporter mouse that expresses a Cre-inducible luciferase from Gaussia princeps (GLuc), which is secreted by cells in an energy-consuming process and can be measured quantitatively in the blood as a marker for the viable tumor load.

Partial p53 reactivation is sufficient to induce cancer regression.

Background: Impaired p53 function is one of the central molecular features of a tumor cell and even a partial reduction in p53 activity can increase the cancer risk in mice and men. From a therapeutic perspective it is noteworthy that tumor cells often become addicted to the absence of p53 providing a rationale for developing p53 reactivating compounds to treat cancer patients. Unfortunately, many of the compounds that are currently undergoing preclinical and clinical testing fail to fully reactivate mutant p53 proteins, raising the crucial question: how much p53 activity is needed to elicit a therapeutic effect?

Methods: We have genetically modelled partial p53 reactivation using knock-in mice with inducible expression of the p53 variant E177R.

p53 partial loss-of-function mutations sensitize to chemotherapy.

The tumor suppressive transcription factor p53 is frequently inactivated in cancer cells by missense mutations that cluster in the DNA binding domain. 30% hit mutational hotspot residues, resulting in a complete loss of transcriptional activity and mutant p53-driven chemotherapy resistance. Of the remaining 70% of non-hotspot mutants, many are partial loss-of-function (partial-LOF) mutants with residual transcriptional activity.

Rely on Each Other: DNA Binding Cooperativity Shapes p53 Functions in Tumor Suppression and Cancer Therapy.

p53 is a tumor suppressor that is mutated in half of all cancers. The high clinical relevance has made p53 a model transcription factor for delineating general mechanisms of transcriptional regulation. p53 forms tetramers that bind DNA in a highly cooperative manner.

mTOR-mediated cancer drug resistance suppresses autophagy and generates a druggable metabolic vulnerability.

Cancer cells have a characteristic metabolism, mostly caused by alterations in signal transduction networks rather than mutations in metabolic enzymes. For metabolic drugs to be cancer-selective, signaling alterations need to be identified that confer a druggable vulnerability. Here, we demonstrate that many tumor cells with an acquired cancer drug resistance exhibit increased sensitivity to mechanistically distinct inhibitors of cancer metabolism.

Phosphorylation Control of p53 DNA-Binding Cooperativity Balances Tumorigenesis and Aging.

Posttranslational modifications are essential for regulating the transcription factor p53, which binds DNA in a highly cooperative manner to control expression of a plethora of tumor-suppressive programs. Here we show at the biochemical, cellular, and organismal level that the cooperative nature of DNA binding is reduced by phosphorylation of highly conserved serine residues (human S183/S185, mouse S180) in the DNA-binding domain. To explore the role of this inhibitory phosphorylation , new phosphorylation-deficient p53-S180A knock-in mice were generated.

Inactivation of Mdm2 restores apoptosis proficiency of cooperativity mutant p53 in vivo.

mutations are found in 50% of all cancers and mutated status is considered poor for treatment. However, some mutations exhibit only partial loss-of-function (LOF), meaning they retain residual transcriptional and non-transcriptional activities that are potentially beneficial for therapy. Earlier we have characterized a knock-in mouse model for the partial LOF mutant (p53RR).

Loss of p53 function at late stages of tumorigenesis confers ARF-dependent vulnerability to p53 reactivation therapy.

Cancer development is driven by activated oncogenes and loss of tumor suppressors. While oncogene inhibitors have entered routine clinical practice, tumor suppressor reactivation therapy remains to be established. For the most frequently inactivated tumor suppressor p53, genetic mouse models have demonstrated regression of p53-null tumors upon p53 reactivation.

Residual apoptotic activity of a tumorigenic p53 mutant improves cancer therapy responses.

Engineered p53 mutant mice are valuable tools for delineating p53 functions in tumor suppression and cancer therapy. Here, we have introduced the R178E mutation into the Trp53 gene of mice to specifically ablate the cooperative nature of p53 DNA binding. Trp53 mice show no detectable target gene regulation and, at first sight, are largely indistinguishable from Trp53 mice.

p53 gain-of-function mutations promote metastasis via ENTPD5 upregulation and enhanced N-glycoprotein folding.

Mutations in cancer abolish normal tumor suppressive functions of tumor protein p53 (, best known as p53) and convert it into an oncogene. We recently reported the identification of ectonucleoside triphosphate diphosphohydrolase 5 () as a transcriptional target of mutant p53 that enhances folding of N-glycosylated proteins required for cancer cell migration, invasion, and metastasis.

Mutant p53 promotes tumor progression and metastasis by the endoplasmic reticulum UDPase ENTPD5.

Mutations in the p53 tumor suppressor gene are the most frequent genetic alteration in cancer and are often associated with progression from benign to invasive stages with metastatic potential. Mutations inactivate tumor suppression by p53, and some endow the protein with novel gain of function (GOF) properties that actively promote tumor progression and metastasis. By comparative gene expression profiling of p53-mutated and p53-depleted cancer cells, we identified ectonucleoside triphosphate diphosphohydrolase 5 (ENTPD5) as a mutant p53 target gene, which functions as a uridine 5'-diphosphatase (UDPase) in the endoplasmic reticulum (ER) to promote the folding of N-glycosylated membrane proteins.

Drying of Pigment-Cellulose Nanofibril Substrates.

A new substrate containing cellulose nanofibrils and inorganic pigment particles has been developed for printed electronics applications. The studied composite structure contains 80% fillers and is mechanically stable and flexible. Before drying, the solids content can be as low as 20% due to the high water binding capacity of the cellulose nanofibrils.

Monitoring the dynamics of clonal tumour evolution in vivo using secreted luciferases.

Tumours are heterogeneous cell populations that undergo clonal evolution during tumour progression, metastasis and response to therapy. Short hairpin RNAs (shRNAs) generate stable loss-of-function phenotypes and are versatile experimental tools to explore the contribution of individual genetic alterations to clonal evolution. In these experiments tumour cells carrying shRNAs are commonly tracked with fluorescent reporters.

p53 DNA binding cooperativity is essential for apoptosis and tumor suppression in vivo.

Four molecules of the tumor suppressor p53 assemble to cooperatively bind proapoptotic target genes. The structural basis for cooperativity consists of interactions between adjacent DNA binding domains. Mutations at the interaction interface that compromise cooperativity were identified in cancer patients, suggesting a requirement of cooperativity for tumor suppression.

Increased subventricular zone-derived cortical neurogenesis after ischemic lesion.

In adult rodents stroke enhances neurogenesis resulting in the addition of neurons to forebrain regions such as striatum or cortex where postnatal neurogenesis under normal conditions plays a negligible role. In the cortex, new neurons are generated either from local cortical precursors that are activated by stroke or from precursors residing in the subventricular zone (SVZ) of lateral ventricles that under normal conditions supply neuroblasts by and large only for the olfactory bulb. In this study we used 5HT3A-EGFP transgenic mice in which all neuroblasts originating in the SVZ are EGFP-labeled.

Cdc25 phosphatases are required for timely assembly of CDK1-cyclin B at the G2/M transition.

Progression through mitosis requires the coordinated regulation of Cdk1 kinase activity. Activation of Cdk1 is a multistep process comprising binding of Cdk1 to cyclin B, relocation of cyclin-kinase complexes to the nucleus, activating phosphorylation of Cdk1 on Thr(161) by the Cdk-activating kinase (CAK; Cdk7 in metazoans), and removal of inhibitory Thr(14) and Tyr(15) phosphorylations. This dephosphorylation is catalyzed by the dual specific Cdc25 phosphatases, which occur in three isoforms in mammalian cells, Cdc25A, -B, and -C.

Human Cdc25A phosphatase has a non-redundant function in G2 phase by activating Cyclin A-dependent kinases.

Cdc25 phosphatases activate Cdk/Cyclin complexes by dephosphorylation and thus promote cell cycle progression. We observed that the peak activity of Cdc25A precedes the one of Cdc25B in prophase and the maximum of Cyclin/Cdk kinase activity. Furthermore, Cdc25A activates both Cdk1-2/Cyclin A and Cdk1/Cyclin B complexes while Cdc25B seems to be involved only in activation of Cdk1/Cyclin B.

Wip1 phosphatase regulates p53-dependent apoptosis of stem cells and tumorigenesis in the mouse intestine.

Colorectal cancer is one of the major causes of cancer-related deaths. To gain further insights into the mechanisms underlying its development, we investigated the role of Wip1 phosphatase, which is highly expressed in intestinal stem cells, in the mouse model of APC(Min)-driven polyposis. We found that Wip1 removal increased the life span of APC(Min) mice through a significant suppression of polyp formation.

Wip1 phosphatase modulates ATM-dependent signaling pathways.

Deletion of Ppm1d, the gene encoding the Wip1 phosphatase, renders cells resistant to transformation and mice resistant to tumor development. Here, we report that deficiency of Wip1 resulted in activation of the ataxia-telangiectasia mutated (ATM) kinase. In turn, overexpression of Wip1 was sufficient to reduce activation of the ATM-dependent signaling cascade after DNA damage.

A subtle change in p38 MAPK activity is sufficient to suppress in vivo tumorigenesis.

Emerging evidence supports a role for p38 MAPK in negative regulation of tumorigenesis. Here we show that a subtle activation of p38 MAPK is sufficient to suppress tumorigenesis as measured by the ability to form tumors when MKK6-inducible cells were explanted into nude mice. On the other hand, this activation of p38 MAPK did not necessarily cause an immediate inhibition of cell growth in vitro as measured by standard MTS assay.

Inactivation of the Wip1 phosphatase inhibits mammary tumorigenesis through p38 MAPK-mediated activation of the p16(Ink4a)-p19(Arf) pathway.

Modulation of tumor suppressor activities may provide new opportunities for cancer therapy. Here we show that disruption of the gene Ppm1d encoding Wip1 phosphatase activated the p53 and p16 (also called Ink4a)-p19 (also called ARF) pathways through p38 MAPK signaling and suppressed in vitro transformation of mouse embryo fibroblasts (MEFs) by oncogenes. Disruption of the gene Cdkn2a (encoding p16 and p19), but not of Trp53 (encoding p53), reconstituted cell transformation in Ppm1d-null MEFs.