Structural Centrosome Aberrations Research Articles

High-throughput electron tomography identifies centriole over-elongation as an early event in plasma cell disorders

Plasma cell disorders are clonal outgrowths of pre-malignant or malignant plasma cells, characterized by extensive chromosomal aberrations. Centrosome abnormalities are a major driver of chromosomal instability in cancer but their origin, incidence, and composition in primary tumor cells is poorly understood. Using cutting-edge, semi-automated high-throughput electron tomography, we characterized at nanoscale 1386 centrioles in CD138pos plasma cells from eight healthy donors and 21 patients with plasma cell disorders, and 722 centrioles from different control populations. In plasma cells from healthy individuals, over-elongated centrioles accumulated with age. In plasma cell disorders, centriole over-elongation was notably frequent in early, pre-malignant disease stages, became less pronounced in overt multiple myeloma, and almost entirely disappeared in aggressive plasma cell leukemia. Centrioles in other types of patient-derived B cell neoplasms showed no over-elongation. In contrast to current belief, centriole length appears to be highly variable in long-lived, healthy plasma cells, and over-elongation and structural aberrations are common in this cell type. Our data suggest that structural centrosome aberrations accumulate with age in healthy CD138pos plasma cells and may thus play an important role in early aneuploidization as an oncogenic driver in plasma cell disorders.

A high-throughput electron tomography workflow reveals over-elongated centrioles in relapsed/refractory multiple myeloma

Electron microscopy is the gold standard to characterize centrosomal ultrastructure. However, production of significant morphometrical data is highly limited by acquisition time. We therefore developed a generalizable, semi-automated high-throughput electron tomography strategy to study centrosome aberrations in sparse patient-derived cancer cells at nanoscale. As proof of principle, we present electron tomography data on 455 centrioles of CD138pos plasma cells from one patient with relapsed/refractory multiple myeloma and CD138neg bone marrow mononuclear cells from three healthy donors as a control. Plasma cells from the myeloma patient displayed 122 over-elongated centrioles (48.8%). Particularly mother centrioles also harbored gross structural abnormalities, including fragmentation and disturbed microtubule cylinder formation, while control centrioles were phenotypically unremarkable. These data demonstrate the feasibility of our scalable high-throughput electron tomography strategy to study structural centrosome aberrations in primary tumor cells. Moreover, our electron tomography workflow and data provide a resource for the characterization of cell organelles beyond centrosomes.

Multi-Modality Imaging Reveals Structural Centrosome Aberrations As a Potential Driver of Chromosomal Instability in Early-Stage Plasma Cell Disorders

Multi-Modality Imaging Reveals Structural Centrosome Aberrations As a Potential Driver of Chromosomal Instability in Early-Stage Plasma Cell Disorders

Abstract P6-06-03: Mechanobiology of cancer cells and tumour microenvironment jointly regulates cancer cell invasion and onset of metastasis

Abstract Mechanical properties of cancer cells and their microenvironment play a critical role in cancer progression and metastatic dissemination. We have established an in vitro assay using native human basement membrane (BM) to study interactions with normal epithelial cells in terms of BM composition, architecture and stiffness. We showed that these are required to act jointly in order to achieve apico-basal polarity, tissue barrier formation and specific stiffness to maintain healthy epithelial tissues. In contrast, in cancer the onset of metastasis occurs when cancer cells invade and breach the BM. For example, it is well known that cancer cells can perforate BM using proteolysis. However, recently we have demonstrated that in presence of carcinoma-associated fibroblasts (CAFs) isolated from cancer patients, moderately invasive cancer cells were able to invade into surrounding stromal matrix in a metalloproteinase-independent manner. In fact cell invasion was associated with decrease in stiffness and correlated to changes in cell and BM morphology. Using live imaging and atomic force microscopy (AFM), we could visualise CAFs actively pulling, stretching and softening the BM, forming gaps through which cancer cells can migrate. By exerting contractile forces, CAFs altered the organisation and physical properties of native BM, making it permissive for cancer cell invasion. Also recently we showed that from the epithelial side, structural centrosome aberrations known to accompany breast cancer progression can create local stiffness heterogeneity that triggers the escape of soft cells undergoing mitosis. In particular, we demonstrated that structural centrosome aberrations can trigger cell dissemination through a non-cell-autonomous mechanism, raising the prospect that centrosome aberrations might facilitate dissemination of soft metastatic cells. In summary, physical interactions between cancer cells and the extracellular matrix (ECM) components contribute to softening of specific cancer cells, physical activation of stromal cells such as CAFs to facilitate cancer invasion and metastases. By extending these findings to a routine clinical setting we measured nanomechanical profiles of biopises from breast cancer patients in a physiological tissue protective solution thus preserving tissue viability and allowing for further pathohistological analysis of the same specimens. Conclusively, we demonstrated how detecting highly deformable cancer cells in patient tissues can serve as a unique marker of cancer aggressiveness thus potentially enabling treatment optimization and development of novel treatment strategies. Citation Format: Marija Plodinec, Philipp Oertle, Alexandre Glentis, Danijela Vignjevic, Olivier Ganier, Eric Nigg, Tobias Appenzeller, Ahmed Jizawi, Flora Scott, Cristian Raez, Marko Loparic, Zlatko Marusic, Ellen C. Obermann, Rosemarie Burian, Roderick Y.H. Lim. Mechanobiology of cancer cells and tumour microenvironment jointly regulates cancer cell invasion and onset of metastasis [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-06-03.

Structural centrosome aberrations sensitize polarized epithelia to basal cell extrusion.

Centrosome aberrations disrupt tissue architecture and may confer invasive properties to cancer cells. Here we show that structural centrosome aberrations, induced by overexpression of either Ninein-like protein (NLP) or CEP131/AZI1, sensitize polarized mammalian epithelia to basal cell extrusion. While unperturbed epithelia typically dispose of damaged cells through apical dissemination into luminal cavities, certain oncogenic mutations cause a switch in directionality towards basal cell extrusion, raising the potential for metastatic cell dissemination. Here we report that NLP-induced centrosome aberrations trigger the preferential extrusion of damaged cells towards the basal surface of epithelial monolayers. This switch in directionality from apical to basal dissemination coincides with a profound reorganization of the microtubule cytoskeleton, which in turn prevents the contractile ring repositioning that is required to support extrusion towards the apical surface. While the basal extrusion of cells harbouring NLP-induced centrosome aberrations requires exogenously induced cell damage, structural centrosome aberrations induced by excess CEP131 trigger the spontaneous dissemination of dying cells towards the basal surface from MDCK cysts. Thus, similar to oncogenic mutations, structural centrosome aberrations can favour basal extrusion of damaged cells from polarized epithelia. Assuming that additional mutations may promote cell survival, this process could sensitize epithelia to disseminate potentially metastatic cells.

Structural centrosome aberrations promote non-cell-autonomous invasiveness.

Centrosomes are the main microtubule‐organizing centers of animal cells. Although centrosome aberrations are common in tumors, their consequences remain subject to debate. Here, we studied the impact of structural centrosome aberrations, induced by deregulated expression of ninein‐like protein (NLP), on epithelial spheres grown in Matrigel matrices. We demonstrate that NLP‐induced structural centrosome aberrations trigger the escape (“budding”) of living cells from epithelia. Remarkably, all cells disseminating into the matrix were undergoing mitosis. This invasive behavior reflects a novel mechanism that depends on the acquisition of two distinct properties. First, NLP‐induced centrosome aberrations trigger a re‐organization of the cytoskeleton, which stabilizes microtubules and weakens E‐cadherin junctions during mitosis. Second, atomic force microscopy reveals that cells harboring these centrosome aberrations display increased stiffness. As a consequence, mitotic cells are pushed out of mosaic epithelia, particularly if they lack centrosome aberrations. We conclude that centrosome aberrations can trigger cell dissemination through a novel, non‐cell‐autonomous mechanism, raising the prospect that centrosome aberrations contribute to the dissemination of metastatic cells harboring normal centrosomes.

Centrosome aberrations and chromosome instability contribute to tumorigenesis and intra-tumor heterogeneity.

Centrosomes serve as the major microtubule organizing centers in cells and thereby contribute to cell shape, polarity, and motility. Also, centrosomes ensure equal chromosome segregation during mitosis. Centrosome aberrations arise when the centrosome cycle is deregulated, or as a result of cytokinesis failure. A long-standing postulate is that centrosome aberrations are involved in the initiation and progression of cancer. However, this notion has been a subject of controversy because until recently the relationship has been correlative. Recently, it was shown that numerical or structural centrosome aberrations can initiate tumors in certain tissues in mice, as well as invasion. Particularly, we will focus on centrosome amplification and chromosome instability as drivers of intra-tumor heterogeneity and their consequences in cancer. We will also discuss briefly the controversies surrounding this theory to highlight the fact that the role of both centrosome amplification and chromosome instability in cancer is highly context-dependent. Further, we will discuss single-cell sequencing as a novel technique to understand intra-tumor heterogeneity and some therapeutic approaches to target chromosome instability.

Impact of Centrosome Aberrations on Chromosome Segregation and Tissue Architecture in Cancer.

Centrosomes determine the disposition of microtubule networks and thereby contribute to regulate cell shape, polarity, and motility, as well as chromosome segregation during cell division. Additionally, centrioles, the core components of centrosomes, are required for the formation of cilia and flagella. Mutations in genes coding for centrosomal and centriolar proteins are responsible for several human diseases, foremost ciliopathies and developmental disorders resulting in small brains (primary microcephaly) or small body size (dwarfism). Moreover, a long-standing postulate implicates numerical and/or structural centrosome aberrations in the etiology of cancer. In this review, we will discuss recent work on the role of centrosome aberrations in the promotion of genome instability and the disruption of tissue architecture, two hallmarks of human cancers. We will emphasize recent studies on the impact of centrosome aberrations on the polarity of epithelial cells cultured in three-dimensional spheroid models. Collectively, the results from these in vitro systems suggest that different types of centrosome aberrations can promote invasive behavior through different pathways. Particularly exciting is recent evidence indicating that centrosome aberrations may trigger the dissemination of potentially metastatic cells through a non-cell-autonomous mechanism.

Structural centrosome aberrations favor proliferation by abrogating microtubule-dependent tissue integrity of breast epithelial mammospheres

Structural centrosome aberrations are frequently observed in early stage carcinomas, but their role in malignant transformation is poorly understood. Here, we examined the impact of overexpression of Ninein-like protein (Nlp) on the architecture of polarized epithelia in three-dimensional mammospheres. When Nlp was overexpressed to levels resembling those seen in human tumors, it formed striking centrosome-related bodies (CRBs), which sequestered Ninein and affected the kinetics of microtubule (MT) nucleation and release. In turn, the profound reorganization of the MT cytoskeleton resulted in mislocalization of several adhesion and junction proteins as well as the tumor suppressor Scribble, resulting in the disruption of epithelial polarity, cell-cell interactions and mammosphere architecture. Remarkably, cells harboring Nlp-CRBs displayed an enhanced proliferative response to epidermal growth factor. These results demonstrate that structural centrosome aberrations cause not only the disruption of epithelial polarity but also favor overproliferation, two phenotypes typically associated with human carcinomas.

CEP63 deficiency promotes p53-dependent microcephaly and reveals a role for the centrosome in meiotic recombination.

CEP63 is a centrosomal protein that facilitates centriole duplication and is regulated by the DNA damage response. Mutations in CEP63 cause Seckel syndrome, a human disease characterized by microcephaly and dwarfism. Here we demonstrate that Cep63 deficient mice recapitulate Seckel syndrome pathology. The attrition of neural progenitor cells involves p53-dependent cell death and brain size is rescued by the deletion of p53. Cell death is not the result of an aberrant DNA damage response but is triggered by centrosome-based mitotic errors. In addition, Cep63 loss severely impairs meiotic recombination, leading to profound male infertility. Cep63 deficient spermatocytes display numerical and structural centrosome aberrations, chromosome entanglements and defective telomere clustering, suggesting that a reduction in centrosome-mediated chromosome movements underlies recombination failure. Our results provide novel insight into the molecular pathology of microcephaly and establish a role for the centrosome in meiotic recombination.

Numerical and structural centrosome aberrations are an early and stable event in the adenoma–carcinoma sequence of colorectal carcinomas

Numerical and structural centrosome changes have been described for and linked with genetic instability in solid tumors. Here, we specifically address centrosome aberrations in the adenoma-carcinoma sequence of colorectal cancer by detailed evaluation of gamma-tubulin staining patterns. Formalin-fixed and paraffin-embedded specimens (normal colonic epithelium n=21; low-grade intraepithelial neoplasia n=27, high-grade intraepithelial neoplasia n=16 and invasive adenocarcinomas n=33) were stained by an anti-gamma-tubulin antibody using standard immunofluorescence. Three-dimensional image stacks of the stainings were recorded (Zeiss LSM510 confocal microscope), followed by numerical and structural data analysis (DIAS software package) and statistical evaluation (NCSS-software). The mean centrosome signal per cell differed significantly (P<0.0001) between normal colonic epithelium (0.8775) and each low-grade intraepithelial neoplasia (1.787), high-grade intraepithelial neoplasia (2.259) and invasive carcinomas (2.267). Similarly, both the centrosomes' structural entropy (SE) and minimal spanning tree (MST) differed significantly (P<0.001) between normal (SE=3.956, MST=38.78) and each low- (SE=6.39, MST=26) and high-grade intraepithelial neoplasia (SE=5.75, MST=26.97) and invasive carcinoma (SE=6.86, MST=28.08). Numerical and structural centrosome dysregulation is seen as early as in low-grade dysplastic lesions of the adenoma-carcinoma sequence of colorectal carcinomas and may, as such, play an initial role in the carcinogenic process.

Centrosome Aberrations in Chronic Myeloid Leukemia (CML) Are Correlated with Disease Progression and Chromosome Instability.

Purpose: Numerical and structural centrosome abnormalities are hallmarks of a variety of cancers and have been implicated in chromosome missegregation, chromosomal instability, and aneuploidy. These phenomena already occur in preneoplastic lesions like oral leukoplakia, early cervical neoplasias, and small benign tumors of colon and breast. Moreover, deviations from normal karyotype seem to increase as tumors enlarge and become malignant. Genetic instability is a common feature in chronic myeloid leukemia (CML). We sought to establish a relationship between centrosome abnormalities and cytogenetic aberrations in CD34+ cells from CML patients at diagnosis (chronic phase - CP) and in blast crisis (BC).Methods: Diagnosis of CML was established by hematologic, cytogenetic and molecular parameters. Treatment was performed according to the protocols of the German CML study group (www.kompetenznetz-leukaemie.de). CD34+ cells from ten umbilical cord blood specimens served as negative controls. Centrosome number and morphology were analyzed by immunofluorescence microscopy. In brief, CD34+ cells from ficollized peripheral blood samples were concentrated by magnetic cell sorting (MACS) and cytospun onto coated slides. After methanol fixation cells were incubated with antibodies directed to centrosomal proteins Pericentrin and gamma-Tubulin. Antibody-antigen complexes were stained by incubation with FITC- and Cy3-conjugated secondary antibodies.Results: CML CP samples tested at initial diagnosis (n=20) already displayed numerical and structural centrosome aberrations (30.0% +/−2.3) as compared with corresponding normal control cells (n=10) (2.3% +/−1.1). In BC samples (n=10) an increase of centrosome aberrations was observed (58.0% +/−2.0).Conclusion: The findings suggest that centrosome defects in CML occur early and are already present at primary diagnosis. Centrosome defects may contribute to disease progression by generation of further chromosome instability leading to accumulation of alleles carrying pro-oncogenic mutations and loss of alleles containing normal tumor suppressor genes and thus accelerating complex genomic changes associated with CML BC.

Improved grading of breast adenocarcinomas based on genomic instability.

Numerous investigations have shown that in primary breast adenocarcinomas DNA aneuploidy in contrast to DNA diploidy indicates high malignancy potential. On the basis of the study of 104 breast carcinomas, we describe a subtype of aneuploidy, which demonstrates a low degree of malignancy. In image cytometric DNA histograms, this subtype possessed a low percentage (< or = 8.8%) of nonmodal DNA values as measured by the stemline scatter index (SSI), which is defined as sum of the percentage of cells in the S-phase region, the G(2) exceeding rate and the coefficient of variation of the tumor stemline. The cut point of SSI = 8.8% (P = 0.03) enabled us to also subdivide diploid and tetraploid tumors into clinically low and high malignant variants. One possible reason for aneuploidy is impaired distribution of chromosomes at mitosis caused by numerical or structural centrosome aberrations. Cyclins A and E seem to be involved in centrosome duplication. Real-time quantitative PCR measurements of cyclin A and E transcript levels and immunohistochemical determination of cyclin A protein expression showed statistically significantly increased values in the tumors with a high SSI (>8.8%), compared with those with a low SSI. A pilot study demonstrated centrosomal aberrations in an average of 9.6% of the measured cells in four aneuploid carcinomas with high SSI values and in an average of 2.5% of the cells in three aneuploid and three diploid tumors with low SSI. Our data indicate that the SSI, most likely reflecting the degree of genomic instability, allows additional classifying of the known aneuploid, diploid, and tetraploid categories of primary breast adenocarcinomas into low and high malignant subtypes.

Centrosome aberrations as a possible mechanism for chromosomal instability in non-Hodgkin's lymphoma.

Recently, centrosome aberrations have been described as a possible cause of aneuploidy in many solid tumors. To investigate whether centrosome aberrations occur in non-Hodgkin's lymphoma (NHL) and correlate with histologic subtype, karyotype, and other biological disease features, we examined 24 follicular lymphomas (FL), 18 diffuse large-B-cell lymphomas (DLCL), 33 mantle cell lymphomas (MCL), and 17 extranodal marginal zone B-cell lymphomas (MZBCL), using antibodies to centrosomal proteins. All 92 NHL displayed numerical and structural centrosome aberrations as compared to nonmalignant lymphoid tissue. Centrosome abnormalities were detectable in 32.3% of the cells in NHL, but in only 5.5% of lymphoid cells from 30 control individuals (P<0.0001). Indolent FL and MZBCL contained only 25.8 and 28.8% cells with abnormal centrosomes. In contrast, aggressive DLCL and MCL harbored centrosome aberrations in 41.8 and 35.0% of the cells, respectively (P<0.0001). Centrosomal aberrations correlated to lymphoma grade, mitotic, and proliferation indices, but not to the p53 labeling index. Importantly, diploid MCL contained 31.2% cells with abnormal centrosomes, while tetraploid samples harbored centrosome aberrations in 55.6% of the cells (P<0.0001). These results indicate that centrosome defects are common in NHL and suggest that they may contribute to the acquisition of chromosomal instability typically seen in NHL.

Centrosome aberrations in acute myeloid leukemia are correlated with cytogenetic risk profile

AbstractGenetic instability is a common feature in acute myeloid leukemia (AML). Centrosome aberrations have been described as a possible cause of aneuploidy in many human tumors. To investigate whether centrosome aberrations correlate with cytogenetic findings in AML, we examined a set of 51 AML samples by using a centrosome-specific antibody to pericentrin. All 51 AML samples analyzed displayed numerical and structural centrosome aberrations (36.0% ± 16.6%) as compared with peripheral blood mononuclear cells from 21 healthy volunteers (5.2% ± 2.0%;P< .0001). In comparison to AML samples with normal chromosome count, the extent of numerical and structural centrosome aberrations was higher in samples with numerical chromosome changes (50.5% ± 14.2% versus 34.3% ± 12.2%;P< .0001). When the frequency of centrosome aberrations was analyzed within cytogenetically defined risk groups, we found a correlation of the extent of centrosome abnormalities to all 3 risk groups (P= .0015), defined as favorable (22.5% ± 7.3%), intermediate (35.3% ± 13.1%), and adverse (50.3% ± 15.6%). These results indicate that centrosome defects may contribute to the acquisition of chromosome aberrations and thereby to the prognosis in AML.

The centrosome cycle

The centrosome is the major microtubule-organizing center of animal cells. It influences cell shape and polarity and directs the formation of the bipolar mitotic spindle. Numerical and structural centrosome aberrations have been implicated in disease, notably cancer. In dividing cells, centrosomes need to be duplicated and segregated in synchrony with chromosomes. This centrosome cycle requires a series of structural and functional transitions that are regulated by both phosphorylation and proteolysis. Here we summarize recent information on the regulation of the centrosome cycle and its coordination with the chromosomal cell cycle.