Aneuploid Cancer Cells Research Articles

Effects of aneuploidy on gene expression: implications for cancer.

Unbalanced chromosome content, so-called aneuploidy, is a hallmark of cancer cells. Changes in the copy numbers of chromosomes or large chromosomal regions significantly alter the expression of several hundreds of genes that are gained or lost. At the same time, aneuploidy per se affects the transcription of many genes throughout the entire genome, as several pathways are activated or inhibited in response to changes in chromosome copy number. In recent years, a large amount of quantitative genome, transcriptome and proteome data has enabled comparison of the changes in gene expression observed in aneuploid cancer cells, as well as in model aneuploid cells with defined karyotypes. Here, we summarize how aneuploidy shapes gene expression and how it may contribute to the phenotypes of cancer cells.

Replication stress activates DNA repair synthesis in mitosis.

Oncogene-induced DNA replication stress has been implicated as a driver of tumorigenesis. Many chromosomal rearrangements characteristic of human cancers originate from specific regions of the genome called common fragile sites (CFSs). CFSs are difficult-to-replicate loci that manifest as gaps or breaks on metaphase chromosomes (termed CFS 'expression'), particularly when cells have been exposed to replicative stress. The MUS81-EME1 structure-specific endonuclease promotes the appearance of chromosome gaps or breaks at CFSs following replicative stress. Here we show that entry of cells into mitotic prophase triggers the recruitment of MUS81 to CFSs. The nuclease activity of MUS81 then promotes POLD3-dependent DNA synthesis at CFSs, which serves to minimize chromosome mis-segregation and non-disjunction. We propose that the attempted condensation of incompletely duplicated loci in early mitosis serves as the trigger for completion of DNA replication at CFS loci in human cells. Given that this POLD3-dependent mitotic DNA synthesis is enhanced in aneuploid cancer cells that exhibit intrinsically high levels of chromosomal instability (CIN(+)) and replicative stress, we suggest that targeting this pathway could represent a new therapeutic approach.

Chronic centrosome amplification without tumorigenesis

Centrosomes are microtubule-organizing centers that facilitate bipolar mitotic spindle assembly and chromosome segregation. Recognizing that centrosome amplification is a common feature of aneuploid cancer cells, we tested whether supernumerary centrosomes are sufficient to drive tumor development. To do this, we constructed and analyzed mice in which centrosome amplification can be induced by a Cre-recombinase-mediated increase in expression of Polo-like kinase 4 (Plk4). Elevated Plk4 in mouse fibroblasts produced supernumerary centrosomes and enhanced the expected mitotic errors, but proliferation continued only after inactivation of the p53 tumor suppressor. Increasing Plk4 levels in mice with functional p53 produced centrosome amplification in liver and skin, but this did not promote spontaneous tumor development in these tissues or enhance the growth of chemically induced skin tumors. In the absence of p53, Plk4 overexpression generated widespread centrosome amplification, but did not drive additional tumors or affect development of the fatal thymic lymphomas that arise in animals lacking p53. We conclude that, independent of p53 status, supernumerary centrosomes are not sufficient to drive tumor formation.

Abstract 3008: CEP55 is a determinant of genomic instability in aneuploid breast cancer cells and facilitates anti-mitotic drugs resistance by interacting directly with HSF1

Abstract Centrosomal proteins have long been known to act as a scaffolds, spindle checkpoint regulators as well as key regulating elements of microtubule organizing centre, hence as an essential component of cell cycle progression. CEP55 is a centrosomal protein originally identified as an indispensable regulator of cytokinesis, the final stage of cell division that divides cytoplasm equally amongst two daughter cells. Failure to faithfully complete cytokinesis due to loss of CEP55 resulted in primary genetic lesion leading to multinucleated cells, thus promotes tumourigenesis and aneuploidy. CEP55 has been to shown elevated in wide range of cancers including breast cancer, however the molecular mechanisms on how CEP55 mediated genomic instability in cancers are still not well understood. To decipher the functional role of CEP55 in regulating genomic instability in breast cancer, through a series of in-vitro and in-vivo experiments we found that high levels of CEP55 is significantly associates with basal-like breast cancer subtype with poor overall survival, relapse free survival and distant-metastasis free survival. Furthermore, we found that depletion of CEP55 decreased cell viability due to induction of apoptosis and hamper primary tumour growth due to clearance of aneuploid cells that are particularly important in oncogenic transformation. In addition, depletion of CEP55 hindered premature exit of mitotic arrested cells and this is partly mediated through CEP55-dependent interaction with HSF1 during mitosis to facilitate development of aneuploidy. Strikingly, we found that CEP55 mediates anti-mitotic drug resistance to docetaxel and PLK1 inhibition. Depletion of CEP55 increased sensitivity to anti-mitotic drugs in particular docetaxel or PLK1 inhibitor, providing a rationale to target CEP55 and its dependent-pathways in aggressive and aneuploid breast cancer. Citation Format: Murugan Kalimutho, Nicola Waddell, Jessie Jeffry, Sriganesh Srihari, Kum Kum Khanna. CEP55 is a determinant of genomic instability in aneuploid breast cancer cells and facilitates anti-mitotic drugs resistance by interacting directly with HSF1. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3008. doi:10.1158/1538-7445.AM2015-3008

Targeting MPS1 Enhances Radiosensitization of Human Glioblastoma by Modulating DNA Repair Proteins.

To ensure faithful chromosome segregation, cells use the spindle assembly checkpoint (SAC), which can be activated in aneuploid cancer cells. Targeting the components of SAC machinery required for the growth of aneuploid cells may offer a cancer cell-specific therapeutic approach. In this study, the effects of inhibiting Monopolar spindle 1, MPS1 (TTK), an essential SAC kinase, on the radiosensitization of glioblastoma (GBM) cells were analyzed. Clonogenic survival was used to determine the effects of the MPS1 inhibitor NMS-P715 on radiosensitivity in multiple model systems, including GBM cell lines, a normal astrocyte, and a normal fibroblast cell line. DNA double-strand breaks (DSB) were evaluated using γH2AX foci, and cell death was measured by mitotic catastrophe evaluation. Transcriptome analysis was performed via unbiased microarray expression profiling. Tumor xenografts grown from GBM cells were used in tumor growth delay studies. Inhibition of MPS1 activity resulted in reduced GBM cell proliferation. Furthermore, NMS-P715 enhanced the radiosensitivity of GBM cells by decreased repair of DSBs and induction of postradiation mitotic catastrophe. NMS-P715 in combination with fractionated doses of radiation significantly enhanced the tumor growth delay. Molecular profiling of MPS1-silenced GBM cells showed an altered expression of transcripts associated with DNA damage, repair, and replication, including the DNA-dependent protein kinase (PRKDC/DNAPK). Next, inhibition of MPS1 blocked two important DNA repair pathways. In conclusion, these results not only highlight a role for MPS1 kinase in DNA repair and as prognostic marker but also indicate it as a viable option in glioblastoma therapy. Inhibition of MPS1 kinase in combination with radiation represents a promising new approach for glioblastoma and for other cancer therapies.

RT-18 * TARGETING MPS1 ENHANCES RADIOSENSITIZATION OF HUMAN GLIOBLASTOMA BY MODULATING DNA REPAIR PROTEINS

During the cell cycle, genomic stability requires accurate chromosome segregation. Errors in this process can cause aneuploidy, leading to tumorigenesis. To ensure faithful chromosome segregation, cells use the spindle assembly checkpoint (SAC) mechanism. However, in aneuploid cancer cells components of the SAC machinery are frequently altered. Thus, targeting the components of SAC machinery required for the growth of aneuploid cells may thus offer a cancer cell specific therapeutic approach. Monopolar spindle 1 (MPS1) is an essential SAC kinase involved in determining spindle integrity. MPS1 is overexpressed in a wide range of tumors and is required for tumor cell proliferation; there is thus increased interest in targeting MPS1 for cancer treatment. In this study, we have analyzed the mechanistic basis of the effects of inhibiting MPS1 in glioblastoma multiforme (GBM). We show that the inhibition of MPS1 in conjunction with radiation reduces GBM cell growth, and clonogenic survival and that this is associated with mitotic cell arrest and induction of mitotic catastrophe. MNS-P715 not alone, but along with fractionated doses of radiation significantly enhanced the tumor growth delay. Using gene expression profiling of GBM cells in which MPS1 was silenced we identified altered expression of genes associated with DNA damage, DNA repair, and DNA replication, including PRKDC, the DNA-dependent protein kinase (DNAPK). Inhibition of MPS1 blocked two important DNA repair pathways, non-homologous end joining and homologous recombination. To our knowledge, this is the first report demonstrating a role for MPS1 in DNA repair. Data mining of publically available databases showed the clinical relevance of MPS1 as an important cancer target in GBM. We conclude that inhibiting MPS1 kinase in combination with DNA damage, including irradiation, could represent a promising new approach to cancer therapy.

The haplotype-resolved genome and epigenome of the aneuploid HeLa cancer cell line

SummaryThe HeLa cell line was established in 1951 from cervical cancer cells taken from a patient, Henrietta Lacks, marking the first successful attempt to continually culture human-derived cells in vitro1. HeLa’s robust growth and unrestricted distribution resulted in its broad adoption – both intentionally and through widespread cross-contamination2 – and for the past sixty years it has served a role analogous to that of a model organism3. Its cumulative impact is illustrated by the fact that HeLa is named in >74,000 or ~0.3% of PubMed abstracts. The genomic architecture of HeLa remains largely unexplored beyond its karyotype4, in part because like many cancers, its extensive aneuploidy renders such analyses challenging. We performed haplotype-resolved whole genome sequencing5 of the HeLa CCL-2 strain, discovering point and indel variation, mapping copy-number and loss of heterozygosity (LOH), and phasing variants across full chromosome arms. We further investigated variation and copy-number profiles for HeLa S3 and eight additional strains. Surprisingly, HeLa is relatively stable with respect to point variation, accumulating few new mutations since early passaging. Haplotype resolution facilitated reconstruction of an amplified, highly rearranged region at chromosome 8q24.21 at which the HPV-18 viral genome integrated as the likely initial event underlying tumorigenesis. We combined these maps with RNA-Seq6 and ENCODE Project7 datasets to phase the HeLa epigenome, revealing strong, haplotype-specific activation of the proto-oncogene MYC by the integrated HPV-18 genome ~500 kilobases upstream, and permitting global analyses of the relationship between gene dosage and expression. These data provide an extensively phased, high-quality reference genome for past and future experiments relying on HeLa, and demonstrate the value of haplotype resolution for characterizing cancer genomes and epigenomes.

Elevated Tolerance to Aneuploidy in Cancer Cells: Estimating the Fitness Effects of Chromosome Number Alterations by In Silico Modelling of Somatic Genome Evolution

An unbalanced chromosome number (aneuploidy) is present in most malignant tumours and has been attributed to mitotic mis-segregation of chromosomes. However, recent studies have shown a relatively high rate of chromosomal mis-segregation also in non-neoplastic human cells, while the frequency of aneuploid cells remains low throughout life in most normal tissues. This implies that newly formed aneuploid cells are subject to negative selection in healthy tissues and that attenuation of this selection could contribute to aneuploidy in cancer. To test this, we modelled cellular growth as discrete time branching processes, during which chromosome gains and losses were generated and their host cells subjected to selection pressures of various magnitudes. We then assessed experimentally the frequency of chromosomal mis-segregation as well as the prevalence of aneuploid cells in human non-neoplastic cells and in cancer cells. Integrating these data into our models allowed estimation of the fitness reduction resulting from a single chromosome copy number change to an average of ≈30% in normal cells. In comparison, cancer cells showed an average fitness reduction of only 6% (p = 0.0008), indicative of aneuploidy tolerance. Simulations based on the combined presence of chromosomal mis-segregation and aneuploidy tolerance reproduced distributions of chromosome aberrations in >400 cancer cases with higher fidelity than models based on chromosomal mis-segregation alone. Reverse engineering of aneuploid cancer cell development in silico predicted that aneuploidy intolerance is a stronger limiting factor for clonal expansion of aneuploid cells than chromosomal mis-segregation rate. In conclusion, our findings indicate that not only an elevated chromosomal mis-segregation rate, but also a generalised tolerance to novel chromosomal imbalances contribute to the genomic landscape of human tumours.

Tumour selective targeting of cell cycle kinases for cancer treatment

The deregulation of the cell cycle and checkpoint machinery in cancer presents a highly attractive therapeutic strategy. We review here the strategies used to exploit the dysregulated cell cycle, both through targeting kinases required for cell cycle progression, and checkpoint kinases to inappropriately force cells through the cell cycle. Appropriate control of the cell cycle is critical for proliferating normal cells, and we discuss the importance of defining tumour specific vulnerabilities that could be targeted with cell cycle kinase inhibitors. Recent studies have shown that ER-positive breast cancers rely on CDK4 to promote proliferation. TP53 mutant cancer cell lines are sensitive to WEE1 and CHK1 inhibitors in combination with chemotherapy, while PTEN-deficient aneuploid cancer cell lines are sensitive to TTK inhibitors.

Chromosomal gain promotes formation of a steep RanGTP gradient that drives mitosis in aneuploid cells

Many mitotic factors were shown to be activated by Ran guanosine triphosphatase. Previous studies in Xenopus laevis egg extracts and in highly proliferative cells showed that mitotic chromosomes were surrounded by steep Ran guanosine triphosphate (GTP) concentration gradients, indicating that RanGTP-activated factors promote spindle assembly around chromosomes. However, the mitotic role of Ran in normal differentiated cells is not known. In this paper, we show that although the steep mitotic RanGTP gradients were present in rapidly growing cell lines and were required for chromosome congression in mitotic HeLa cells, the gradients were strongly reduced in slow-growing primary cells, such as HFF-1 fibroblasts. The overexpression of RCC1, the guanine nucleotide exchange factor for Ran, induced steeper mitotic RanGTP gradients in HFF-1 cells, showing the critical role of RCC1 levels in the regulation of mitosis by Ran. Remarkably, in vitro fusion of HFF-1 cells produced cells with steep mitotic RanGTP gradients comparable to HeLa cells, indicating that chromosomal gain can promote mitosis in aneuploid cancer cells via Ran.

Cancer Karyotypes: Survival of the Fittest

Cancer cells are typically characterized by complex karyotypes including both structural and numerical changes, with aneuploidy being a ubiquitous feature. It is becoming increasingly evident that aneuploidy per se can cause chromosome mis-segregation, which explains the higher rates of chromosome gain/loss observed in aneuploid cancer cells compared to normal diploid cells, a phenotype termed chromosomal instability (CIN). CIN can be caused by various mechanisms and results in extensive karyotypic heterogeneity within a cancer cell population. However, despite such karyotypic heterogeneity, cancer cells also display predominant karyotypic patterns. In this review we discuss the mechanisms of CIN, with particular emphasis on the role of aneuploidy on CIN. Further, we discuss the potential functional role of karyotypic patterns in cancer.

Abstract 1817: Characterisation of CCT251455, a novel, selective and highly potent Mps1 kinase inhibitor

Abstract Monopolar spindle 1 (Mps1, also known as TTK) is a dual-specificity, cell cycle-regulated kinase required for the establishment and maintenance of the spindle assembly checkpoint during mitosis. Aneuploid tumour cells possess a weak spindle checkpoint to allow onset of anaphase and cell division. Our hypothesis is that a complete inhibition of an already weakened mitotic checkpoint of cancer cells will cause gross chromosomal abnormalities leading to aneuploid cell death. We have shown that depletion of Mps1 by siRNA induces cell death selectively in aneuploid and PTEN-deficient cancer cell lines. We have demonstrated that Mps1 depletion inhibits MAD2 localisation to the kinetochores. We have developed biochemical and cellular assays for Mps1 activity and a high throughput screening of our Institute's compound library delivered multiple hit series. Medicinal chemistry in combination with X-ray crystallography led to the development of CCT251455, a small molecule inhibitor of Mps1 kinase activity. CCT251455 selectively inhibits Mps1 kinase with an IC50 of 0.003 μM, inhibits growth of a panel of human tumour cell lines with GI50 between 0.06 - 1 μM and is particularly potent in PTEN-deficient cell lines. Cells treated with CCT251455 abrogate nocodazole-induced mitotic arrest and reduce the time spent in mitosis. Mps1-inhibited cells contain aberrant numbers of chromosomes and the majority of cells divide their chromosomes without proper alignment. CCT251455 is orally bioavailable (F = 82%) and shows modulation of biomarkers in vivo. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1817. doi:1538-7445.AM2012-1817

Mechanisms of Ploidy Increase in Human Cancers: A New Role for Cell Cannibalism

Aneuploidy is a hallmark of human cancers originating from abnormal mitoses. Many aneuploid cancer cells also have greater-than-diploid DNA content, suggesting that polyploidy is a common precursor to aneuploidy during tumor progression. Polyploid cells can originate from cell fusion, endoreplication, and cytokinesis failure. Recently we found that cell cannibalism by entosis, a form of cell engulfment involving live cells, also leads to polyploidy, as internalized cells disrupt cytokinesis of their engulfing cell hosts. By this mechanism, cannibalistic cell behavior could promote tumor progression by leading to aneuploidy. Here, we discuss cell cannibalism in cancer and other mechanisms that result in the formation of polyploid cancer cells.

A model for random genetic damage directing selection of diploid or aneuploid tumours

To test whether genetic instability may determine whether tumours become aneuploid or diploid. We have identified genes needed for cell survival or replication by combining Affymetrix gene expression array data from 12 experimental cell lines with in silico GEO+GNF and expO databases. Specific loss of heterozygosis (LOHs), chromosomal abnormalities (called derivative chromosomes) and numbers of normal homologues were identified by SNP and SKY analyses. Random gene losses were calculated under the assumption that bi-allelic MMR gene inactivation causes a 20-fold increase in rate of gene loss. There were ∼1.23 × 10(4) genes widely dispersed throughout the genome and possibly expressed by all cells for survival or proliferation, many of these genes performed housekeeping functions. Conservation of the genes may explain the complete haploid genomes found for 15 different cell types and derivative chromosomes selectively retained in aneuploid cancer cell lines after LOH formations, and normal homologue losses. Loss of cell survival/replication genes was calculated to be higher in colon stem cells of carriers of MMR gene mutations than carriers of APC gene mutations. Random loss of cell survival/replication genes was calculated to be low enough for colon stem cells with APC gene mutations to 'select' LOH and derivative chromosome combinations favouring tumour cell proliferation. However, cell survival/replication gene loss was calculated to be too high for colonic stem cells lacking MMR genes to survive chromosomal instability, explaining why MMR mutations only produce tumours with diploid chromosome cells.

Abstract 2941: Defining novel pathways that arrest genetically unstable tetraploid cells

Abstract Tetraploid cells, which are a common byproduct of cell division failures, are genetically unstable and have the capacity to facilitate tumorigenesis. Consequently, p53-dependent tumor suppression mechanisms exist to limit the continued proliferation of these cells by promoting G1 cell cycle arrest. However, unlike other common cellular insults that activate p53 and promote G1 arrest, such as the DNA damage response, the mechanisms governing G1 arrest in response to tetraploidy remain largely unexplored. To gain insight into these mechanisms, we have developed a novel genome-wide RNAi screening assay to comprehensively identify proteins that are necessary to activate or maintain G1 cell cycle arrest after the induction of tetraploidy. Results from this screen, in combination with complementary bioinformatic approaches, have begun to illuminate the nature of the stresses associated with tetraploidy. More importantly, this work is shedding light on the adaptive mechanisms that tetraploid and near-tetraploid tumors may have evolved in order to overcome these stresses. These findings have the potential to lead to the identification of new pathways that can be targeted by chemotherapeutics to specifically reinforce G1 arrest in grossly aneuploid cancer cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2941. doi:10.1158/1538-7445.AM2011-2941

Occurrence of multipolar mitoses and association with Aurora-A/-B kinases and p53 mutations in aneuploid esophageal carcinoma cells

BackgroundAurora kinases and loss of p53 function are implicated in the carcinogenesis of aneuploid esophageal cancers. Their association with occurrence of multipolar mitoses in the two main histotypes of aneuploid esophageal squamous cell carcinoma (ESCC) and Barrett's adenocarcinoma (BAC) remains unclear. Here, we investigated the occurrence of multipolar mitoses, Aurora-A/-B gene copy numbers and expression/activation as well as p53 alterations in aneuploid ESCC and BAC cancer cell lines.ResultsA control esophageal epithelial cell line (EPC-hTERT) had normal Aurora-A and -B gene copy numbers and expression, was p53 wild type and displayed bipolar mitoses. In contrast, both ESCC (OE21, Kyse-410) and BAC (OE33, OE19) cell lines were aneuploid and displayed elevated gene copy numbers of Aurora-A (chromosome 20 polysomy: OE21, OE33, OE19; gene amplification: Kyse-410) and Aurora-B (chromosome 17 polysomy: OE21, Kyse-410). Aurora-B gene copy numbers were not elevated in OE19 and OE33 cells despite chromosome 17 polysomy. Aurora-A expression and activity (Aurora-A/phosphoT288) was not directly linked to gene copy numbers and was highest in Kyse-410 and OE33 cells. Aurora-B expression and activity (Aurora-B/phosphoT232) was higher in OE21 and Kyse-410 than in OE33 and OE19 cells. The mitotic index was highest in OE21, followed by OE33 > OE19 > Kyse-410 and EPC-hTERT cells. Multipolar mitoses occurred with high frequency in OE33 (13.8 ± 4.2%), followed by OE21 (7.7 ± 5.0%) and Kyse-410 (6.3 ± 2.0%) cells. Single multipolar mitoses occurred in OE19 (1.0 ± 1.0%) cells. Distinct p53 mutations and p53 protein expression patterns were found in all esophageal cancer cell lines, but complete functional p53 inactivation occurred in OE21 and OE33 only.ConclusionsHigh Aurora-A expression alone is not associated with overt multipolar mitoses in aneuploid ESCC and BAC cancer cells, as specifically shown here for OE21 and OE33 cells, respectively. Additional p53 loss of function mutations are necessary for this to occur, at least for invasive esophageal cancer cells. Further assessment of Aurora kinases and p53 interactions in cells or tissue specimens derived from non-invasive dysplasia (ESCC) or intestinal metaplasia (BAC) are necessary to disclose a potential causative role of Aurora kinases and p53 for development of aneuploid, invasive esophageal cancers.

Targeting aneuploid cancer cells

Introduction: Most cancers are characterized by some degree of aneuploidy, although its relevance for tumor initiation or progression and the nature of the initial trigger are still not well understood. It was Theodor Boveri who first suggested a link between aneuploidy and cancer at the beginning of the last century, but it is only recently that the molecular mechanisms involved have started to be uncovered.Areas covered: The molecular mechanisms that are at the origin of aneuploidy and their cellular consequences. Based on these new findings molecular targets have emerged which could lead to a specific treatment of at least some types of aneuploid tumors.Expert opinion: Therapeutic intervention specifically for aneuploid cells is a very promising approach, however, although new promising targets have been spotted they still need to be tested for proof of concept. Targeting the spindle checkpoint could be an interesting approach for cancer therapy, however, as for other mitotic targets, the open question of the therapeutic window and sensitivity of normal hemopoietic cells has to be considered carefully. Future challenges will not only include identifying and validating druggable targets related to the relevant pathways, but also finding predictive biomarkers to define the responding patient population(s).

HDAC2 and TXNL1 distinguish aneuploid from diploid colorectal cancers

DNA aneuploidy has been identified as a prognostic factor for epithelial malignancies. Further understanding of the translation of DNA aneuploidy into protein expression will help to define novel biomarkers to improve therapies and prognosis. DNA ploidy was assessed by image cytometry. Comparison of gel-electrophoresis-based protein expression patterns of three diploid and four aneuploid colorectal cancer cell lines detected 64 ploidy-associated proteins. Proteins were identified by mass spectrometry and subjected to Ingenuity Pathway Analysis resulting in two overlapping high-ranked networks maintaining Cellular Assembly and Organization, Cell Cycle, and Cellular Growth and Proliferation. CAPZA1, TXNL1, and HDAC2 were significantly validated by Western blotting in cell lines and the latter two showed expression differences also in clinical samples using a tissue microarray of normal mucosa (n=19), diploid (n=31), and aneuploid (n=47) carcinomas. The results suggest that distinct protein expression patterns, affecting TXNL1 and HDAC2, distinguish aneuploid with poor prognosis from diploid colorectal cancers.

Identification of Aneuploidy-Selective Antiproliferation Compounds

Aneuploidy, an incorrect chromosome number, is a hallmark of cancer. Compounds that cause lethality in aneuploid, but not euploid, cells could therefore provide new cancer therapies. We have identified the energy stress-inducing agent AICAR, the protein folding inhibitor 17-AAG, and the autophagy inhibitor chloroquine as exhibiting this property. AICAR induces p53-mediated apoptosis in primary mouse embryonic fibroblasts (MEFs) trisomic for chromosome 1, 13, 16, or 19. AICAR and 17-AAG, especially when combined, also show efficacy against aneuploid human cancer cell lines. Our results suggest that compounds that interfere with pathways that are essential for the survival of aneuploid cells could serve as a new treatment strategy against a broad spectrum of human tumors.

Cut homeobox 1 causes chromosomal instability by promoting bipolar division after cytokinesis failure

Cell populations able to generate a large repertoire of genetic variants have increased potential to generate tumor cells that survive through the multiple selection steps involved in tumor progression. A mechanism for the generation of aneuploid cancer cells involves passage through a tetraploid stage. Supernumerary centrosomes, however, can lead to multipolar mitosis and cell death. Using tissue culture and transgenic mouse models of breast cancer, we report that Cut homeobox 1 (CUX1) causes chromosomal instability by activating a transcriptional program that prevents multipolar divisions and enables the survival of tetraploid cells that evolve to become genetically unstable and tumorigenic. Transcriptional targets of CUX1 involved in DNA replication and bipolar mitosis defined a gene expression signature that, across 12 breast cancer gene expression datasets, was associated with poor clinical outcome. The signature not only was higher in breast tumor subtypes of worse prognosis, like the basal-like and HER2(+) subtypes, but also identified poor outcome among estrogen receptor-positive/node-negative tumors, a subgroup considered to be at lower risk. The CUX1 signature therefore represents a unique criterion to stratify patients and provides insight into the molecular determinants of poor clinical outcome.