Chronic spindle assembly checkpoint activation causes myelosuppression and gastrointestinal atrophy.

Interference with microtubule dynamics in mitosis activates the spindle assembly checkpoint (SAC) to prevent chromosome segregation errors. The SAC induces mitotic arrest by inhibiting the anaphase-promoting complex (APC) via the mitotic checkpoint complex (MCC). The MCC component MAD2 neutralizes the critical APC cofactor, CDC20, preventing exit from mitosis.

Weakened APC/C activity at mitotic exit drives cancer vulnerability to KIF18A inhibition.

The efficacy of current antimitotic cancer drugs is limited by toxicity in highly proliferative healthy tissues. A cancer-specific dependency on the microtubule motor protein KIF18A therefore makes it an attractive therapeutic target. Not all cancers require KIF18A, however, and the determinants underlying this distinction remain unclear.

Disruption of the TP53 locus in osteosarcoma leads to TP53 promoter gene fusions and restoration of parts of the TP53 signalling pathway.

TP53 is the most frequently mutated gene in human cancer. This gene shows not only loss-of-function mutations but also recurrent missense mutations with gain-of-function activity. We have studied the primary bone malignancy osteosarcoma, which harbours one of the most rearranged genomes of all cancers.

Centrosome defects cause microcephaly by activating the 53BP1-USP28-TP53 mitotic surveillance pathway.

Mutations in centrosome genes deplete neural progenitor cells (NPCs) during brain development, causing microcephaly. While NPC attrition is linked to TP53-mediated cell death in several microcephaly models, how TP53 is activated remains unclear. In cultured cells, mitotic delays resulting from centrosome loss prevent the growth of unfit daughter cells by activating a pathway involving 53BP1, USP28, and TP53, termed the mitotic surveillance pathway.

PIDDosome-induced p53-dependent ploidy restriction facilitates hepatocarcinogenesis.

Polyploidization frequently precedes tumorigenesis but also occurs during normal development in several tissues. Hepatocyte ploidy is controlled by the PIDDosome during development and regeneration. This multi-protein complex is activated by supernumerary centrosomes to induce p53 and restrict proliferation of polyploid cells, otherwise prone for chromosomal instability.

Loss of NF2 defines a genetic subgroup of non-FOS-rearranged osteoblastoma.

Osteoblastoma is a locally aggressive tumour of bone. Until recently, its underlying genetic features were largely unknown. During the past two years, reports have demonstrated that acquired structural variations affect the transcription factor FOS in a high proportion of cases.

Altering microtubule dynamics is synergistically toxic with spindle assembly checkpoint inhibition.

Chromosomal instability (CIN) and aneuploidy are hallmarks of cancer. As most cancers are aneuploid, targeting aneuploidy or CIN may be an effective way to target a broad spectrum of cancers. Here, we perform two small molecule compound screens to identify drugs that selectively target cells that are aneuploid or exhibit a CIN phenotype.

Genome-wide mapping of sister chromatid exchange events in single yeast cells using Strand-seq.

Homologous recombination involving sister chromatids is the most accurate, and thus most frequently used, form of recombination-mediated DNA repair. Despite its importance, sister chromatid recombination is not easily studied because it does not result in a change in DNA sequence, making recombination between sister chromatids difficult to detect. We have previously developed a novel DNA template strand sequencing technique, called Strand-seq, that can be used to map sister chromatid exchange (SCE) events genome-wide in single cells.

Deletion of the spindle assembly checkpoint gene is tolerated in mouse models of acute T-cell lymphoma and hepatocellular carcinoma.

Chromosome instability (CIN) is deleterious to normal cells because of the burden of aneuploidy. However, most human solid tumors have an abnormal karyotype implying that gain and loss of chromosomes by cancer cells confers a selective advantage. CIN can be induced in the mouse by inactivating the spindle assembly checkpoint.

Centrosome Amplification Is Sufficient to Promote Spontaneous Tumorigenesis in Mammals.

Centrosome amplification is a common feature of human tumors, but whether this is a cause or a consequence of cancer remains unclear. Here, we test the consequence of centrosome amplification by creating mice in which centrosome number can be chronically increased in the absence of additional genetic defects. We show that increasing centrosome number elevated tumor initiation in a mouse model of intestinal neoplasia.

Direct chromosome-length haplotyping by single-cell sequencing.

Haplotypes are fundamental to fully characterize the diploid genome of an individual, yet methods to directly chart the unique genetic makeup of each parental chromosome are lacking. Here we introduce single-cell DNA template strand sequencing (Strand-seq) as a novel approach to phasing diploid genomes along the entire length of all chromosomes. We demonstrate this by building a complete haplotype for a HapMap individual (NA12878) at high accuracy (concordance 99.

Single-cell whole genome sequencing reveals no evidence for common aneuploidy in normal and Alzheimer's disease neurons.

Background: Alzheimer's disease (AD) is a neurodegenerative disease of the brain and the most common form of dementia in the elderly. Aneuploidy, a state in which cells have an abnormal number of chromosomes, has been proposed to play a role in neurodegeneration in AD patients. Several studies using fluorescence in situ hybridization have shown that the brains of AD patients contain an increased number of aneuploid cells.

Single-cell sequencing reveals karyotype heterogeneity in murine and human malignancies.

Background: Chromosome instability leads to aneuploidy, a state in which cells have abnormal numbers of chromosomes, and is found in two out of three cancers. In a chromosomal instable p53 deficient mouse model with accelerated lymphomagenesis, we previously observed whole chromosome copy number changes affecting all lymphoma cells. This suggests that chromosome instability is somehow suppressed in the aneuploid lymphomas or that selection for frequently lost/gained chromosomes out-competes the CIN-imposed mis-segregation.

Ordered progression of stage-specific miRNA profiles in the mouse B2 B-cell lineage.

Micro-RNAs (miRNAs) have been recognized as critical regulators of gene expression, and deregulation of miRNA expression has been implicated in a wide spectrum of diseases. To provide a framework for the role of miRNAs in B-cell development and malignancy, we deep-sequenced miRNAs from B1 cells and 10 developmental stages that can be identified within the mouse B2 B-cell lineage. The expression profiles of the 232 known miRNAs that are expressed during B-cell development display stage-specific induction patterns, yet hierarchical clustering analysis showed relationships that are in full agreement with the model of the B2 B-cell developmental pathway.

Downregulation of active caspase 8 as a mechanism of acquired TRAIL resistance in mismatch repair-proficient colon carcinoma cell lines.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) triggers the apoptotic cascade in various colon cancer cell lines after binding to the membrane receptors DR4 and DR5. However, not all cancer cell lines are sensitive to the therapeutic recombinant human TRAIL (rhTRAIL). To investigate the causes of TRAIL resistance in colon cancer cell lines, models have been developed, mostly in mismatch repair-deficient cells.

Caspase-7 deficiency protects from endotoxin-induced lymphocyte apoptosis and improves survival.

Extensive apoptosis of leukocytes during sepsis and endotoxic shock constitutes an important mechanism linked to the excessive mortality associated with these disorders. Caspase inhibitors confer protection from endotoxin-induced lymphocyte apoptosis and improve survival, but it is not clear which caspases mediate lipopolysaccharide (LPS)-induced lymphocyte apoptosis and mortality. We report here that the apoptotic executioner caspase-7 was activated in the splenocytes of LPS-injected mice, suggesting a role for caspase-7 in lymphocyte apoptosis.

Fas receptor clustering and involvement of the death receptor pathway in rituximab-mediated apoptosis with concomitant sensitization of lymphoma B cells to fas-induced apoptosis.

Ab binding to CD20 has been shown to induce apoptosis in B cells. In this study, we demonstrate that rituximab sensitizes lymphoma B cells to Fas-induced apoptosis in a caspase-8-dependent manner. To elucidate the mechanism by which Rituximab affects Fas-mediated cell death, we investigated rituximab-induced signaling and apoptosis pathways.

Duration of CTL activation regulates IL-2 production required for autonomous clonal expansion.

The extent and magnitude of CD8(+) T lymphocyte (CTL) clonal expansion in vivo depends on the duration of stimulation provided during primary activation, whereas expansion under conventional in vitro conditions fails to reveal this. The molecular details of this differential programming are unclear. We developed a low-density culture system that recapitulates in vivo conditions and enables analysis of both proliferation and survival/apoptosis during primary expansion.

Testicular germ cell tumours: the paradigm of chemo-sensitive solid tumours.

Testicular germ cell tumours (TGCTs) are the most frequent solid malignant tumour in men 20-40 years of age and the most frequent cause of death from solid tumours in this age group. Up to 50% of the patients suffer from metastatic disease at diagnosis. The majority of metastatic testicular cancer patients, in contrast to most other metastatic solid tumours, can be cured with highly effective cisplatin-based chemotherapy.

Tissue distribution of the death ligand TRAIL and its receptors.

Recombinant human (rh) TNF-related apoptosis-inducing ligand (TRAIL) harbors potential as an anticancer agent. RhTRAIL induces apoptosis via the TRAIL receptors TRAIL-R1 and TRAIL-R2 in tumors and is non-toxic to nonhuman primates. Because limited data are available about TRAIL receptor distribution, we performed an immunohistochemical (IHC) analysis of the expression of TRAIL-R1, TRAIL-R2, the anti-apoptotic TRAIL receptor TRAIL-R3, and TRAIL in normal human and chimpanzee tissues.

Low p21Waf1/Cip1 protein level sensitizes testicular germ cell tumor cells to Fas-mediated apoptosis.

In the present study, we investigated the relation between p21 expression and the sensitivity of testicular germ cell tumor (TGCT) cells to apoptotic stimuli. Despite similar cisplatin-induced wild-type p53 accumulation, the TGCT cell lines Tera and Scha expressed low p21 protein and mRNA levels in comparison to A2780 ovarian cancer cells. Inhibition of the proteasome complex with MG-132 increased p21 protein levels in TGCT cells but much more in A2780 cells, whereas cisplatin had no additional effect on p21 protein levels.

Expression of TRAIL and TRAIL death receptors in stage III non-small cell lung cancer tumors.

Purpose: Several in vitro studies have shown that non-small cell lung cancer (NSCLC) cell lines are sensitive to apoptosis induction by the recombinant human (rh) tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) death ligand, indicating that rhTRAIL might become an attractive molecule for treatment of NSCLCs. To investigate the therapeutic potential of rhTRAIL, the expression of TRAIL and its apoptosis-inducing receptors DR4 and DR5 was evaluated in tumors of stage III NSCLC patients.

Experimental Design: Before treatment, tumor biopsies from locally advanced NSCLC patients were obtained by bronchoscopy.

The attractive Achilles heel of germ cell tumours: an inherent sensitivity to apoptosis-inducing stimuli.

Testicular germ cell tumours (TGCTs) are extremely sensitive to cisplatin-containing chemotherapy. The rapid time course of apoptosis induction after exposure to cisplatin suggests that TGCT cells are primed to undergo programmed cell death as an inherent property of the cell of origin. In fact, apoptosis induction of germ cells in the testis is an important physiological mechanism to control the quality and quantity of the gametes produced.