High rate of centrosome aberrations and correlation with proliferative activity in patients with untreated B-cell chronic lymphocytic leukemia

Polymorphism in miRNA target sites of CEP-63 and CEP-152 ring complex influences expression of CEP genes and favors tumorigenesis in glioma

Purpose: The present study was designed to screen the genetic polymorphisms and expression profiling of CEP-152 and CEP-63 genes in brain tumor patients. Methods: The amplification refractory mutation system PCR technique (ARMS-PCR) was used for mutation analysis using 300 blood samples of brain tumor patients and 300 overtly healthy controls. For expression analysis, 150 brain tumor tissue samples along with adjacent uninvolved/normal tissues (controls) were collected. Results: A significantly higher frequency of the mutant genotype of the CEP-152 single nucleotide polymorphism (rs2169757) and CEP-63 single nucleotide polymorphisms (rs9809619 and rs13060247) was observed in patients versus overtly healthy controls. The authors' results showed highly significant deregulation of CEP-152 (p < 0.0001) and CEP-63 (p < 0.0001) in glioma/meningioma tumor tissues versus adjacent normal tissue. Conclusion: The present study showed that variations in CEP-152 and CEP-63 genes were associated with an increased risk of brain tumor.

Centrosome amplification: a quantifiable cancer cell trait with prognostic value in solid malignancies

Numerical and/or structural centrosome amplification (CA) is a hallmark of cancers that is often associated with the aberrant tumor karyotypes and poor clinical outcomes. Mechanistically, CA compromises mitotic fidelity and leads to chromosome instability (CIN), which underlies tumor initiation and progression. Recent technological advances in microscopy and image analysis platforms have enabled better-than-ever detection and quantification of centrosomal aberrancies in cancer. Numerous studies have thenceforth correlated the presence and the degree of CA with indicators of poor prognosis such as higher tumor grade and ability to recur and metastasize. We have pioneered a novel semi-automated pipeline that integrates immunofluorescence confocal microscopy with digital image analysis to yield a quantitative centrosome amplification score (CAS), which is a summation of the severity and frequency of structural and numerical centrosome aberrations in tumor samples. Recent studies in breast cancer show that CA increases across the disease progression continuum, while normal breast tissue exhibited the lowest CA, followed by cancer-adjacent apparently normal, ductal carcinoma in situ and invasive tumors, which showed the highest CA. This finding strengthens the notion that CA could be evolutionarily favored and can promote tumor progression and metastasis. In this review, we discuss the prevalence, extent, and severity of CA in various solid cancer types, the utility of quantifying amplified centrosomes as an independent prognostic marker. We also highlight the clinical feasibility of a CA-based risk score for predicting recurrence, metastasis, and overall prognosis in patients with solid cancers.

Centrosome Aberration Frequency and Disease Association in B-Acute Lymphoblastic Leukemia

Recent developments in genome-wide genetic analysis in B-acute lymphoblastic leukemia (B-ALL) have provided insight into disease pathogenesis and prognosis. B-ALL cases usually carry a primary genetic event, often a chromosome translocation, and a constellation of secondary genetic alterations that are acquired and selected dynamically in a nonlinear fashion. As far as we are aware of, for the first time, we studied centrosome aberration in patients with B-ALL to understand the progression of the disease. A cytogenetic study was carried out by GTG-banded karyotyping and fluorescence in situ hybridization. DNA index study was carried out with flow cytometry. Indirect immunostaining of centrosomes was performed on mononuclear cells using primary and corresponding secondary antibodies for centrosome-specific protein γ-tubulin. Three primary and corresponding secondary antibodies to three different centrosome-specific proteins, namely α-tubulin, γ-tubulin and pericentrin, were used for indirect immunostaining. The study was carried out on 50 patients with B-ALL. Centrosomal abnormalities were detected in 36 (72%) patients and the remainder (28%) had normal centrosome structure and numbers. Out of these 36 patients with abnormal centrosome, structural abnormalities were detected in 12 (33.3%) and numerical abnormalities in six (16.6%). Both structural and numerical aberrations were detected in 18 (50%) patients. When correlated with the cytogenetic and DNA index findings, 26/27 (96.2%) patients had centrosome defects concomitant with both abnormal karyotype and aneuploidy. Out of 50 patients with B-ALL, 17 (34%) had normal karyotype detected by both karyotype and DNA index, among these, seven (41.17%) patients had centrosome aberration. The morphological and structural abnormalities of the centrosome present in B-ALL cells have a role in disease development and can be considered as prognostic markers.

ILK Induction in Lymphoid Organs by a TNFα-NF-κB-Regulated Pathway Promotes the Development of Chronic Lymphocytic Leukemia

The proliferation of chronic lymphocytic leukemia (CLL) cells requires communication with the lymphoid organ microenvironment. Integrin-linked kinase (ILK) is a multifunctional intracellular adaptor protein that transmits extracellular signals to regulate malignant cell motility, metastasis, and cell-cycle progression, but is poorly characterized in hematologic malignancies. In this study, we investigated the role of ILK in the context of CLL and observed high ILK expression in patient samples, particularly in tumor cells harboring prognostic high-risk markers such as unmutated IGHV genes, high Zap70, or CD38 expression, or a signature of recent proliferation. We also found increased numbers of Ki67 (MKI67)-positive cells in regions of enhanced ILK expression in lymph nodes from CLL patients. Using coculture conditions mimicking the proliferative lymph node microenvironment, we detected a parallel induction of ILK and cyclin D1 (CCND1) expression in CLL cells that was dependent on the activation of NF-κB signaling by soluble TNFα. The newly synthesized ILK protein colocalized to centrosomal structures and was required for correct centrosome clustering and mitotic spindle organization. Furthermore, we established a mouse model of CLL in which B-cell-specific genetic ablation of ILK resulted in decelerated leukemia development due to reduced organ infiltration and proliferation of CLL cells. Collectively, our findings describe a TNFα-NF-κB-mediated mechanism by which ILK expression is induced in the lymph node microenvironment and propose that ILK promotes leukemogenesis by enabling CLL cells to cope with centrosomal defects acquired during malignant transformation. Cancer Res; 76(8); 2186-96. ©2016 AACR.

Mutations in microRNA binding sites of CEP genes involved in cancer

The CEP genes play a pivotal role in the replication of the cell. CEP family proteins form the major constituents of the centrosome and play a prominent role in centriole biogenesis and in cell replication. Alteration in CEP genes will result in disruption of cell cycle that may in turn cause cancer. In our study, we found that 16 of the CEP genes are a potential target to miRNA that binds to complementary sequences in 3'untranslated regions (UTR) of mRNA and stop them from translation. Single nucleotide polymorphisms (SNPs) occurring naturally in such miRNA binding site can alter the miRNA: mRNA interaction and can significantly alter gene expression. We developed a systematic computational pipeline that integrates data from well-established databases, followed stringent selection criteria and identified a panel of 44 high-confidence SNPs that may impair miRNA target sites in the 3'UTR of 16 genes. Further we performed expression analysis to shed light on the potential tissues that might be affected by mutation, enrichment analysis to find the metabolic functions of the gene, and network analysis to highlight the important interactions of CEP genes with other genes to provide insight that complex network will be disturbed upon mutation. In this study, we explored and prioritised the SNPs in CEP gene which could act as a potential target in centrosome-associated human disease. Our analysis would provide a thoughtful insight to wet lab researches to understand the expression pattern of CEP genes and binding phenomenon of mRNA and miRNA upon mutation, which is responsible for inhibition of translation process at genomic levels.

CEP proteins: the knights of centrosome dynasty

Centrosome forms the backbone of cell cycle progression mechanism. Recent debates have occurred regarding the essentiality of centrosome in cell cycle regulation. CEP family protein is the active component of centrosome and plays a vital role in centriole biogenesis and cell cycle progression control. A total of 31 proteins have been categorized into CEP family protein category and many more are under candidate evaluation. Furthermore, by the recent advancements in genomics and proteomics researches, several new CEP proteins have also been characterized. Here we have summarized the importance of CEP family proteins and their regulation mechanism involved in proper cell cycle progression. Further, we have reviewed the detailed molecular mechanism behind the associated pathological phenotypes and the possible therapeutic approaches. Proteins such as CEP57, CEP63, CEP152, CEP164, and CEP215 have been extensively studied with a detailed description of their molecular mechanisms, which are among the primary targets for drug discovery. Moreover, CEP27, CEP55, CEP70, CEP110, CEP120, CEP135, CEP192, CEP250, CEP290, and CEP350 also seem promising for future drug discovery approaches. Since the overview implicates that the overall researches on CEP proteins are not yet able to present significant details required for effective therapeutics development, thus, it is timely to discuss the importance of future investigations in this field.

Characterization and expressional analysis of Dleu7 during Xenopus tropicalis embryogenesis

We characterized the genomic structure and developmental expression of the Dleu7 (deleted in lymphocytic leukemia, 7) gene in Xenopus tropicalis and the evolution of the gene across species. Within the protein-coding sequence (CDS) region, X. tropicalis Dleu7 consists of two exons and one intron. However, bioinformatic analysis indicates that this 211-amino-acid protein contains no obvious functional domains or known motifs. Reverse-transcription polymerase chain reaction and whole-mount in situ hybridization results revealed that, in addition to its expression in the blood island region, some regions of the central nervous system, and subdomains of the neural tube, X. tropicalis Dleu7 is zygotically expressed primarily in mesoderm tissues such as notochord and muscles during early embryogenesis. Expression in notochord is consistent with results from genome-wide association studies suggesting that DLEU7 is related to human adult height. Expression in the blood island region, where blood cell precursors (including B cells) are generated, implies a potential conserved role for Dleu7 in B-cell development between amphibians and mammals. Expression of Dleu7 in some regions of the central nervous system and subdomains of the neural tube also suggests other functions in development. Phylogenetic analysis indicated that Dleu7 is a vertebrate-specific gene and undergoes strong selective pressure in lower vertebrates but is functionally constrained in higher mammals. When subcellular localization was examined by overexpression of enhanced green fluorescent protein fusion protein, Dleu7 showed centrosome localization with main distribution in cytoplasm. Treating gastrula embryos with SU5402, a small molecular inhibitor of the fibroblast growth factor (FGF) receptor, confirmed that Dleu7 expression in mesoderm is regulated by FGF signaling. Our data provide important clues for pathogenesis and physiology during development from the perspective of evolutionary conservation.

Losing balance: the origin and impact of aneuploidy in cancer

Most solid human tumours are aneuploid, that is, they contain an abnormal number of chromosomes. Paradoxically, however, aneuploidy has been reported to induce a stress response that suppresses cellular proliferation in vitro. Here, we review the progress in our understanding of the causes and effects of aneuploidy in cancer and discuss how, in specific contexts, aneuploidy can provide a growth advantage and facilitate cellular transformation. We also explore the emerging possibilities for targeting the cause or consequences of aneuploidy therapeutically.

A clinical overview of centrosome amplification in human cancers

The turn of the 21st century had witnessed a surge of interest in the centrosome and its causal relation to human cancer development - a postulate that has existed for almost a century. Centrosome amplification (CA) is frequently detected in a growing list of human cancers, both solid and haematological, and is a candidate "hallmark" of cancer cells. Several lines of evidence support the progressive involvement of CA in the transition from early to advanced stages of carcinogenesis, being also found in pre-neoplastic lesions and even in histopathologically-normal tissue. CA constitutes the major mechanism leading to chromosomal instability and aneuploidy, via the formation of multipolar spindles and chromosomal missegregation. Clinically, CA may translate to a greater risk for initiation of malignant transformation, tumour progression, chemoresistance and ultimately, poor patient prognosis. As mechanisms underlying CA are progressively being unravelled, the centrosome has emerged as a novel candidate target for cancer treatment. This Review summarizes mainly the clinical studies performed to date focusing on the mechanisms underlying CA in human neoplasia, and highlights the potential utility of centrosomes in the diagnosis, prognosis and treatment of human cancers.

Centrosome function in cancer: guilty or innocent?

The regulation of centrosome number and function underlies bipolar mitotic spindle formation and genetic integrity. Cancer cells both in culture and in situ exhibit a wide range of centrosome abnormalities. Here, we briefly review advances in our understanding of the pathways that govern normal centrosome function and outline the potential causes and consequences of their deregulation in disease. There is ample observational but little experimental evidence to support the conventional model that centrosome dysfunction causes genomic instability and, as a result, cancer. This model has been challenged by recent studies that have uncovered evidence of a direct link between centrosome function in asymmetric cell division and tumourigenesis. Thus, it is timely to discuss the provocative idea that, in certain tissues, abnormal centrosomes drive malignant transformation not by generating genomic instability but by deregulating asymmetric cell division.

The presence of high-risk chromosome aberrations in chronic lymphocytic leukaemia does not correlate with centrosome aberrations

Chromosome aberrations are frequently found in B-cell chronic lymphocytic leukaemia (B-CLL), and specific chromosome aberrations identify poor prognostic subgroups. Almost all the aberrations identified in B-CLL involve loci where genes with a role in the regulation of centrosome duplication have been mapped. Centrosome aberrations have been described as a possible cause of numerical chromosome abnormalities in both solid and haematological tumours. However, little is known about the possible role of centrosome aberrations in B-CLL. To investigate whether centrosome aberrations do occur in B-CLL and correlate with cytogenetically defined prognostic subgroups, we examined a set of 64 B-CLL samples by immunofluorescent staining. B-CLL cases differed significantly from controls in the mean frequency of cells with centrosome aberrations, while no difference was found between subgroups with or without specific chromosome aberrations. Our results indicated that although centrosome aberrations were a common feature in B-CLL, they did not represent a reliable prognostic marker.