Spindle proteins Aurora A and BUB1B, but not Mad2, are aberrantly expressed in dysplastic mucosa of patients with longstanding ulcerative colitis

Potential Signature Therapeutic Biomarkers TOP2A, MAD2L1, and CDK1 in Colorectal Cancer: A Systems Biomedicine-Based Approach

Colorectal cancer is the third deadliest and fourth most diagnosed cancer. It is heterogeneously driven by varied mutations and mutagens, and thus, it is challenging for targeted therapy. The rapid advancement of high-throughput technology presents considerable opportunities for discovering new colon cancer biomarkers. In the present study, we have explored and identified the biomarkers based on molecular interactions. We curated cancer datasets that were not micro-dissected and performed gene expression analysis. The protein-protein interactions were curated, and a network was constructed for the up-regulated genes. The hub genes were analyzed using 12 different topological parameters. The correlation analysis selected TOP2A, CDK1, CCNB1, AURKA, and MAD2L1 as hub genes. Further, survival analysis was performed to determine the effectiveness of the hub gene on the patient's survival rate. Our findings explore various transcription factors such as E2F4, FOXM1, E2F6, MAX, and SIN3A, along with kinases CSNK2A1, MAPK14, CDK1, CDK4, and CDK2, as potential molecular signatures and aid researchers in understanding the pathophysiological mechanisms underlying CRC development and thus providing novel therapeutic and diagnostic recourse. Furthermore, investigating miRNAs, we focused on hsa-miR-215-5p, hsa-miR-192-5p, and hsa-miR-193b-3p due to their observed impact on a diverse set of colorectal cancer genes. Thereby, the current approach brings into light CRC- related genes at the RNA and protein levels that can potentially act as novel biomarkers opening doors to diagnostic and treatment purposes.

Identification of Key Pathways and Genes in SARS-CoV-2 Infecting Human Intestines by Bioinformatics Analysis

COVID-19 is a serious infectious disease that has recently swept the world, and research on its causative virus, SARS-CoV-2, remains insufficient. Therefore, this study uses bioinformatics analysis techniques to explore the human digestive tract diseases that may be caused by SARS-CoV-2 infection. The gene expression profile data set, numbered GSE149312, is from the Gene Expression Omnibus (GEO) database and is divided into a 24-h group and a 60-h group. R software is used to analyze and screen out differentially expressed genes (DEGs) and then gene ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses are performed. In KEGG, the pathway of non-alcoholic fatty liver disease exists in both the 24-h group and 60-h group. STRING is used to establish a protein–protein interaction (PPI) network, and Cytoscape is then used to visualize the PPI and define the top 12 genes of the node as the hub genes. Through verification, nine statistically significant hub genes are identified: AKT1, TIMP1, NOTCH, CCNA2, RRM2, TTK, BUB1B, KIF20A, and PLK1. In conclusion, the results of this study can provide a certain direction and basis for follow-up studies of SARS-CoV-2 infection of the human digestive tract and provide new insights for the prevention and treatment of diseases caused by SARS-CoV-2.

Genetic variants associated with serum alanine aminotransferase levels among patients with hepatitis C virus infection: A genome-wide association study

Information on genetic variants associated with elevated serum alanine aminotransferase (ALT) levels remains limited. A genome-wide association study was performed to identify single-nucleotide polymorphisms (SNPs) associated with ALT levels. The ALT-associated SNP was further evaluated for hepatocellular carcinoma (HCC) risk. A cohort of 892 anti-HCV seropositive patients was used for genome-wide SNP array to examine the associations with baseline ALT levels. SNPs <10^-5 were further tested for associations with serial ALT levels then validated in 486 anti-HCV seropositives. Multinomial logistic regressions were used to estimate odds ratios (ORs) and 95% confidence intervals of SNPs associated with ALT. The SNP was evaluated for HCC risk by using Cox's proportional hazards models. After quality control, 803 participants with 564,464 SNPs were included in the analysis. Of these, 12 SNPs were associated with ALT (p < 10^-5 ). Among the participants, 158 (19.7%) had ALT persistently ≤15 U/L, 327 (40.7%) ever >15 U/L but never >45 U/L, and 318 (39.6%) ever >45 U/L during follow-up. The rs568800 was associated with serial ALT levels, and this was replicated in the external population significantly (p < .05). The A allele (vs C) of rs568800 was associated with ALT >15 U/L but ≤45 U/L and ALT >45 U/L, with the adjusted ORs of 1.41 (1.11-1.78) and 1.86 (1.34-2.60), respectively. The adjusted HRs for HCC were 2.09 (0.90-4.89) for AC and 2.64 (1.13-6.17) for AA (CC as a reference). In conclusion, the rs568800 was associated with serum ALT levels and HCC risk. Clinical utility should be evaluated among patients who have received antivirals.

Identification of Hub Genes in Different Stages of Colorectal Cancer through an Integrated Bioinformatics Approach

Colorectal cancer (CRC) is the third most common cancer that contributes to cancer-related morbidity. However, the differential expression of genes in different phases of CRC is largely unknown. Moreover, very little is known about the role of stress-survival pathways in CRC. We sought to discover the hub genes and identify their roles in several key pathways, including oxidative stress and apoptosis in the different stages of CRC. To identify the hub genes that may be involved in the different stages of CRC, gene expression datasets were obtained from the gene expression omnibus (GEO) database. The differentially expressed genes (DEGs) common among the different datasets for each group were obtained using the robust rank aggregation method. Then, gene enrichment analysis was carried out with Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases. Finally, the protein-protein interaction networks were constructed using the Cytoscape software. We identified 40 hub genes and performed enrichment analysis for each group. We also used the Oncomine database to identify the DEGs related to stress-survival and apoptosis pathways involved in different stages of CRC. In conclusion, the hub genes were found to be enriched in several key pathways, including the cell cycle and p53 signaling pathway. Some of the hub genes were also reported in the stress-survival and apoptosis pathways. The hub DEGs revealed from our study may be used as biomarkers and may explain CRC development and progression mechanisms.

Identification of Core Gene Expression Signature and Key Pathways in Colorectal Cancer

Objective

Colorectal cancer (CRC) is considered the most prevalent malignant tumor that contributes to high cancer-related mortality. However, the signaling pathways involved in CRC and CRC-driven genes are largely unknown. We sought to discover a novel biomarker in CRC.

Materials and Methods

All clinical CRC samples (n = 20) were from Renmin Hospital of Wuhan University. We first selected MAD2L1 by integrated bioinformatics analysis of a GSE dataset. Next, the expression of MAD2L1 in tissues and cell lines was verified by quantitative real-time PCR. The effects of MAD2L1 on cell growth, proliferation, the cell cycle, and apoptosis were examined by in vitro assays.

Results

We identified 683 shared DEGs (420 upregulated and 263 downregulated), and the top twenty genes (CDK1, CCNA2, TOP2A, PLK1, MAD2L1, AURKA, BUB1B, UBE2C, TPX2, RRM2, KIF11, NCAPG, MELK, NUSAP1, MCM4, RFC4, PTTG1, CHEK1, CEP55, DTL) were selected by integrated analysis. These hub genes were significantly overexpressed in CRC samples and were positively correlated. Our data revealed that the expression of MAD2L1 in CRC tissues is higher than that in normal tissues. MAD2L1 knockdown significantly suppressed CRC cell growth by impairing cell cycle progression and inducing cell apoptosis.

Conclusion

MAD2L1, as a novel oncogenic gene, plays a role in regulating cancer cell growth and apoptosis and could be used as a new biomarker for diagnosis and therapy in CRC.

Identification of potential hub genes via bioinformatics analysis combined with experimental verification in colorectal cancer

Colorectal cancer (CRC) is a kind of malignant cancer with high morbidity and mortality. The purpose of this study was to explore potential regulated key genes involved in CRC through bioinformatics analysis and experimental verification. The gene expression profile data were downloaded from the Gene Expression Omnibus, and the differential expression genes were detected in cancerous and paracancerous samples of CRC patients, respectively. Then functional enrichment analysis, such as the Kyoto Encyclopedia of Genes and Genomes pathway analysis as well as the protein-protein interaction network were constructed, and the highly related genes were clustered by Molecular COmplex DEtection algorithm to find out the core interaction in different genes' crosstalk. The genes affecting CRC prognosis were screened by the Human Protein Atlas database. In addition, the expression level of core genes was detected by GEPIA database, and the core genes' changes in large-scale cancer genome data set were directly analyzed by cBioPortal database. The expression of the predicted hub genes DSN1, AHCY, and ERCC6L was verified by reverse-transcription quantitative polymerase chain reaction in CRC cells. The gene function of DSN1 was analyzed by wound healing and colony formation assays. The results showed that silencing of DSN1 could significantly reduce the migration and proliferation of CRC cells. Further, BUB1B, the potential interacting protein of DSN1, was also predicted via bioinformatics analysis. Above all, this study shows that bioinformatics analysis combined with experimental method verification provide more potential vital genes for the prevention and therapy of CRC.

A new role for Drosophila Aurora-A in maintaining chromosome integrity

Aurora-A is a conserved mitotic kinase overexpressed in many types of cancer. Growing evidence shows that Aurora-A plays a crucial role in DNA damage response (DDR) although this aspect has been less characterized. We isolated a new aur-A mutation, named aur-A⁹⁴⁹, in Drosophila, and we showed that it causes chromosome aberrations (CABs). In addition, aur-A⁹⁴⁹ mutants were sensitive to X-ray treatment and showed impaired γ-H2Av foci dissolution kinetics. To identify the pathway in which Aur-A works, we conducted an epistasis analysis by evaluating CAB frequencies in double mutants carrying aur-A⁹⁴⁹ mutation combined to mutations in genes related to DNA damage response (DDR). We found that mutations in tefu (ATM) and in the histone variant H2Av were epistatic over aur-A⁹⁴⁹ indicating that Aur-A works in DDR and that it is required for γ-H2Av foci dissolution. More interestingly, we found that a mutation in lig4, a gene belonging to the non-homologous end joining (NHEJ) repair pathway, was epistatic over aur-A⁹⁴⁹. Based on studies in other systems, which show that phosphorylation is important to target Lig4 for degradation, we hypothesized that in aur-A⁹⁴⁹ mutant cells, there is a persistence of Lig4 that could be, in the end, responsible for CABs. Finally, we observed a synergistic interaction between Aur-A and the homologous recombination (HR) repair system component Rad 51 in the process that converts chromatid deletions into isochromatid deletions. Altogether, these data indicate that Aur-A depletion can elicit chromosome damage. This conclusion should be taken into consideration, since some anticancer therapies are aimed at reducing Aurora-A expression.

CCNA2 acts as a novel biomarker in regulating the growth and apoptosis of colorectal cancer

OBJECTIVE

Colorectal cancer (CRC) is considered to be the most prevalent malignant tumors that contribute to high cancer-related mortality. However, the signaling pathways involved in CRC and CRC-driven genes are largely unknown. We seek to discover a novel biomarker in CRC.

MATERIALS AND METHODS

All clinical CRC samples (n=33) were from Xiangya Hospital. We first selected CCNA2 by integrated bioinformatics analysis of four GSE databases. Next, the expression of CCNA2 in tissues and cell lines was verified by quantitative real-time PCR. The effects of CCNA2 on cell growth, proliferation, cell cycle, and apoptosis were examined by in vitro assays.

RESULTS

We identified 498 shared DEGs (294 upregulated and 204 downregulated), and the top ten hub genes were selected by integrated analysis. These hub genes were significantly overexpressed in CRC samples and were positively correlated. Our data revealed that the expression of CCNA2 in CRC tissues is higher than that in normal tissues. The CCNA2 knockdown could significantly suppress CRC cell growth by impairing cell cycle progression and inducing cell apoptosis.

CONCLUSION

CCNA2, as a novel oncogenic gene, plays a role in regulating cancer cell growth and apoptosis. It could be used as a new biomarker for diagnosis and therapy in CRC.

Aurora kinase A interacts with H-Ras and potentiates Ras-MAPK signaling

In cancer, upregulated Ras promotes cellular transformation and proliferation in part through activation of oncogenic Ras-MAPK signaling. While directly inhibiting Ras has proven challenging, new insights into Ras regulation through protein-protein interactions may offer unique opportunities for therapeutic intervention. Here we report the identification and validation of Aurora kinase A (Aurora A) as a novel Ras binding protein. We demonstrate that the kinase domain of Aurora A mediates the interaction with the N-terminal domain of H-Ras. Further more, the interaction of Aurora A and H-Ras exists in a protein complex with Raf-1. We show that binding of H-Ras to Raf-1 and subsequent MAPK signaling is enhanced by Aurora A, and requires active H-Ras. Thus, the functional linkage between Aurora A and the H-Ras/Raf-1 protein complex may provide a mechanism for Aurora A's oncogenic activity through direct activation of the Ras/MAPK pathway.

Nondysplastic Ulcerative Colitis Has High Levels of the Homologous Recombination Repair Protein NUCKS1 and Low Levels of the DNA Damage Marker Gamma-H2AX

BACKGROUND

The colon and rectum are continuously exposed to oxidative stress that generates reactive oxygen species, which are a major cause of DNA double-strand breaks (DSB). Furthermore, chronic inflammatory diseases such as ulcerative colitis (UC) are characterized by an excess of reactive nitrogen species that can also lead to DNA double-strand breakage and genomic instability. We investigated the expression of the nuclear casein kinase and cyclin-dependent kinase substrate 1 (NUCKS1) protein in UC and sporadic colorectal cancer (CRC) due to its involvement in both DNA double-strand break repair and inflammatory signaling.

METHODS

NUCKS1 expression and expression of the DNA double-strand break marker gamma-H2AX (γH2AX) were assessed in formalin-fixed, paraffin-embedded UC and CRC patient biopsies using peroxidase immunohistochemistry. Expression levels for both proteins were evaluated together with previously published expression-level data for hTERT and TP53 proteins in the same material.

RESULTS

Nondysplastic UC lesions had 10-fold lower γH2AX expression and approximately 4-fold higher NUCKS1 expression compared with sporadic CRC, indicating minimal DNA DSB damage and heightened DNA DSB repair in these lesions, respectively. NUCKS1 expression in UC tended to decrease with increasing grades of dysplasia, whereas γH2AX, hTERT, and TP53 expression tended to increase with increasing grades of dysplasia. The highest γH2AX expression was seen in sporadic CRC, indicating considerable DNA DSB damage, whereas the highest NUCKS1 expression and hTERT expression were seen in nondysplastic UC.

CONCLUSIONS

Overall, our data suggest that NUCKS1 may be involved in DNA DSB repair and/or inflammatory signaling in UC, but a more thorough investigation of both pathways in UC is warranted.

Combining aneuploidy and dysplasia for colitis' cancer risk assessment outperforms current surveillance efficiency: a meta-analysis

PURPOSE

Cancer risk assessment for ulcerative colitis patients by evaluating histological changes through colonoscopy surveillance is still challenging. Thus, additional parameters of high prognostic impact for the development of colitis-associated carcinoma are necessary. This meta-analysis was conducted to clarify the value of aneuploidy as predictor for individual cancer risk compared with current surveillance parameters.

METHODS

A systematic web-based search identified studies published in English that addressed the relevance of the ploidy status for individual cancer risk during surveillance in comparison to neoplastic mucosal changes. The resulting data were included into a meta-analysis, and odds ratios (OR) were calculated for aneuploidy or dysplasia or aneuploidy plus dysplasia.

RESULTS

Twelve studies addressing the relevance of aneuploidy compared to dyplasia were comprehensively evaluated and further used for meta-analysis. The meta-analysis revealed that aneuploidy (OR 5.31 [95 % CI 2.03, 13.93]) is an equally effective parameter for cancer risk assessment in ulcerative colitis patients as dysplasia (OR 4.93 [1.61, 15.11]). Strikingly, the combined assessment of dysplasia and aneuploidy is superior compared to applying each parameter alone (OR 8.99 [3.08, 26.26]).

CONCLUSIONS

This meta-analysis reveals that aneuploidy is an equally effective parameter for individual cancer risk assessment in ulcerative colitis as the detection of dysplasia. More important, the combined assessment of dysplasia and aneuploidy outperforms the use of each parameter alone. We suggest image cytometry for ploidy assessment to become an additional feature of consensus criteria to individually assess cancer risk in UC.

Association between Ki67 Index and Clinicopathological Features in Colorectal Cancer

BACKGROUND

Conflicting results have been reported about the association between the Ki67 labeling index (Ki67-Li) and clinical outcome in patients with colorectal cancer (CRC).

PATIENTS AND METHODS

Ki67 expression was assessed by immunohistochemistry (IHC) in 2,233 consecutive CRC cases.

RESULTS

We determined 992 cases to have a low and 1,241 cases to have a high Ki67-Li (representing an approximately 44-56% breakdown in distribution between low versus high patients designated by phenotype). Stage III patients with a high Ki67-Li had higher 3-year disease-free survival (DFS) and overall survival (OS) than those with a low Ki67-Li (DFS 70 vs. 61%; p = 0.02 and OS 75 vs. 64%; p = 0.008). We also found significantly improved 3-year progression-free survival (PFS) for stage IV patients in the high versus the low Ki67-Li group (PFS 14 vs. 10%; p = 0.02). Yet, we found no statistical differences in prognosis for stage I and II patients and in OS for stage IV patients between high versus low Ki67-Li (p > 0.05).

CONCLUSION

Our results suggest that high Ki67-Li can be an independent prognostic biomarker to aid the assessment of patient outcomes in both stage III and IV CRC.

Spindle Assembly Checkpoint as a Potential Target in Colorectal Cancer: Current Status and Future Perspectives

Colorectal cancer (CRC), one of the most common malignancies worldwide, is often diagnosed at an advanced stage, and resistance to chemotherapeutic and existing targeted therapy is a major obstacle to its successful treatment. New targets that offer alternative clinical options are therefore urgently needed. Recently, perturbation of the spindle assembly checkpoint (SAC), the surveillance mechanism that maintains anaphase inhibition until all chromosomes reach the metaphase plate, has been regarded as a promising target to fight cancer cells, either alone or in combination regimens. Consistent with this strategy, many cancers, including CRC, exhibit altered expression of SAC genes. In this article, we review our current knowledge on SAC activity status in CRC, and on current anti-CRC strategies and future therapeutic perspectives on the basis of SAC targeting experiments in vitro and in animal models.

Immunohistochemical expression of budding uninhibited by benzimidazole related 1 in leukoplakia and oral squamous cell carcinoma

Background:

Budding uninhibited by benzimidazole related 1 (BUBR1) is an important protein in the mitotic spindle assembly checkpoint. Alterations in expression of BUBR1 have been reported in many premalignant and malignant lesions.

Aim:

To compare the expression of BUBR1 with respect to the normal mucosa and degree of dysplasia in oral leukoplakia (OL) and also with respect to different histopathological grades of oral squamous cell carcinoma (OSCC).

Materials and Methods:

Neutral buffered formalin-fixed and paraffin-embedded biopsy specimens 30 each of normal, OL and OSCC tissue were included in this study. The expression of BUBR1 was detected using immunohistochemistry (IHC). The scores obtained were subjected to ANOVA test.

Results:

Significant correlation was found in immunostaining between normal, dysplasia and OSCC groups with a P value of 0.00001. The expression of BUBR1 was significant when compared with different degrees of dysplasia and in different histopathological grades of OSCC with a P value of 0.00001.

Conclusion:

Higher IHC scores were obtained with increased histopathological grades of OL and OSCC suggesting its role as a prognostic indicator.

Mad2 and BubR1 modulates tumourigenesis and paclitaxel response in MKN45 gastric cancer cells

Aneuploidy and chromosomal instability (CIN) are common features of gastric cancer (GC), but their contribution to carcinogenesis and antitumour therapy response is still poorly understood. Failures in the mitotic checkpoint induced by changes in expression levels of the spindle assembly checkpoint (SAC) proteins cause the missegregation of chromosomes in mitosis as well as aneuploidy. To evaluate the possible contribution of SAC to GC, we analyzed the expression levels of proteins of the mitotic checkpoint complex in a cohort of GC cell lines. We found that the central SAC proteins, Mad2 and BubR1, were the more prominently expressed members in disseminated GC cell lines. Silencing of Mad2 and BubR1 in MKN45 and ST2957 cells decreased their cell proliferation, migration and invasion abilities, indicating that Mad2 and BubR1 could contribute to cellular transformation and tumor progression in GC. We next evaluated whether silencing of SAC proteins could affect the response to microtubule poisons. We discovered that paclitaxel treatment increased cell survival in MKN45 cells interfered for Mad2 or BubR1 expression. However, apoptosis (assessed by caspase-3 activation, PARP proteolysis and levels of antiapoptotic Bcl 2-family members), the DNA damage response (assessed by H2Ax phosphorylation) and exit from mitosis (assessed by Cyclin B degradation and Cdk1 regulation) were activated equally between cells, independently of Mad2 or BubR1-protein levels. In contrast, we observed that the silencing of Mad2 or BubR1 in MKN45 cells showed the induction of a senescence-like phenotype accompanied by cell enlargement, increased senescence-associated β-galactosidase activity and increased IL-6 and IL-8 expression. In addition, the senescent phenotype is highly increased after treatment with PTX, indicating that senescence could prevent tumorigenesis in GC. In conclusion, the results presented here suggest that Mad2 and BubR1 could be used as prognostic markers of tumor progression and new pharmacological targets in the treatment for GC.

miRNA-regulated gene expression differs in celiac disease patients according to the age of presentation

Celiac disease is an intestinal disease which shows different symptoms and clinical manifestations among pediatric and adult patients. These variations could be imputable to age-related changes in gut architecture and intestinal immune system, which could be characterized by gene expression differences possibly regulated by miRNAs. We analyzed a panel of miRNAs and their target genes in duodenal biopsies of Marsh 3AB and 3C pediatric celiac patients, compared to controls. Moreover, to assess variation of expression in plasma samples, we evaluated circulating miRNA levels in controls and patients at diagnosis or on gluten-free diet. We detected a decreased miR-192-5p expression in celiac patients, but no variations in NOD2 and CXCL2, targets previously identified in adults. Conversely, we detected a significant increase in mRNA and protein levels of another target, MAD2L1, protein related to cell cycle control. miR-31-5p and miR-338-3p were down-regulated and their respective targets, FOXP3 and RUNX1, involved in Treg function, resulted up-regulated in celiac patients. Finally, we detected, in celiac patients, an increased expression of miR-21-5p, possibly caused by a regulatory loop with its putative target STAT3, which showed an increased activation in Marsh 3C patients. The analysis of plasma revealed a trend similar to that observed in biopsies, but in presence of gluten-free diet we could not detect circulating miRNAs values comparable to controls. miRNAs and their gene targets showed an altered expression in duodenal mucosa and plasma of celiac disease pediatric patients, and these alterations could be different from adult ones.

Requirement for BUB1B/BUBR1 in tumor progression of lung adenocarcinoma

Lung adenocarcinoma is often discovered as metastatic disease with very poor prognosis. However, much remains unknown about the mechanisms of lung adenocarcinoma tumor progression. In this study we showed that knockdown of BUB1B/BUBR1, a critical mitotic checkpoint protein, significantly inhibited anchorage-independent growth of lung adenocarcinoma cell lines. In allograft and tail vein mouse model studies, BUB1B suppression inhibited primary tumor growth and reduced metastasis to the lung and lymph nodes, resulting in prolonged survival in both tumor prevention and tumor intervention settings. Mechanistic studies revealed that BUB1B knockdown sensitized cells to anoikis. The N-terminal region and GLEBS domain of BUB1B were required for its functions in both anchorage-independent growth and anoikis resistance, whereas the kinase domain was less critical. Overexpression of BUB1B is associated with disease progression and poor survival in human lung adenocarcinoma patients. Collectively, these data reveal a novel function for BUB1B in mediating anchorage-independent survival and growth, thereby facilitating lung adenocarcinoma dissemination during metastasis. Thus, targeting BUB1B could provide potential therapeutic benefit in suppressing metastasis and prolonging survival in lung adenocarcinoma patients.

Clinicopathologic significance of BubR1 and Mad2 overexpression in oral cancer

OBJECTIVES

BubR1 and Mad2 are central components of the mitotic checkpoint complex that inhibits anaphase onset until all chromosomes are correctly aligned at the metaphase plate. We propose to analyse the combined expression of BubR1 and Mad2 and assess its significance to oral squamous cell carcinoma (OSCC) diagnosis and prognosis.

MATERIALS AND METHODS

BubR1 and Mad2 expression was assessed by real-time PCR in OSCC cell lines and in normal human oral keratinocytes, and by immunohistochemistry in 65 patients with OSCC. The results were compared regarding clinicopathological parameters, proliferative activity and survival.

RESULTS

BubR1 and Mad2 transcripts were overexpressed in OSCC cell lines which also exhibited attenuated spindle assembly checkpoint activity. BubR1 and Mad2 were also overexpressed in patients with OSCC. BubR1 expression was associated with advanced stages and larger tumour size in univariate analysis, and with shorter overall survival both in univariate and multivariate analysis. Mad2 overexpression was associated with that of BubR1 and, importantly, high expression of Mad2 and BubR1 was associated with increased cellular proliferation.

CONCLUSION

Our data propose a role for BubR1 and Mad2 in OSCC cellular proliferation, progression and prognosis.

BUB1B promotes multiple myeloma cell proliferation through CDC20/CCNB axis

Multiple myeloma (MM) is the second most common hematopoietic malignancy characterized by plasma cell proliferative disorder. In this study, we disclosed that expression of BUB1B significantly increased in high-risk myeloma patients especially in the most aggressive myeloma genetic subgroups of proliferation. Increased BUB1B expression promotes MM cell proliferation. Mechanism study showed that BUB1B expression was highly correlated to CDC20 and CCNB1/2 expression in MM cells, leading to increased MM cell proliferation. Therefore, BUB1B may be a potential target for MM treatment especially for high-risk MM patients.

TP53/p53 alterations and Aurora A expression in progressor and non-progressor colectomies from patients with longstanding ulcerative colitis

Aneuploidy is a common feature in the colonic mucosa of patients suffering from the inflammatory bowel disease ulcerative colitis (UC) and often precedes the development of dysplasia and cancer. Aneuploidy is assumed to be caused by missegregation of chromosomes during mitosis, often due to a faulty spindle assembly checkpoint. p53 is a tumour suppressor protein known to regulate the spindle assembly checkpoint and is frequently mutated in aneuploid cells. Aurora A is a presumed oncoprotein, also involved in regulation of the spindle assembly checkpoint. In the present study, we examined the mutational frequency of TP53 and the protein levels of p53 in a set of 20 progressor and 10 non-progressor colectomies from patients suffering from longstanding UC. In addition, we re-examined previously published immunohistochemical data on Aurora A expression using the same material. Levels of Aurora A were re-examined with regard to DNA ploidy status and dysplasia within the progressors, as well as in relation to p53 accumulation and TP53 mutational status. We detected p53 accumulation only within the progressor colectomies, where it could be followed back 14 years prior to the colectomies, in pre-colectomy biopsies. TP53 mutations were detected in both progressors and non-progressors. Expression levels of Aurora A were similar in the progressors and non-progressors. Within the group of progressors however, low levels of Aurora A were associated with areas of DNA aneuploidy, as well as with increasing degrees of dysplasia. Our results indicate that alterations in p53 may be an early biomarker of a progressor colon, and that p53 is accumulated early in UC-related carcinogenesis. Furthermore, a decreased Aurora A expression is associated with the development of DNA aneuploidy, as well as with dysplasia in UC progressors.

Reduced hTERT protein levels are associated with DNA aneuploidy in the colonic mucosa of patients suffering from longstanding ulcerative colitis

Longstanding ulcerative colitis (UC) is a disease of chronic inflammation of the colon. It is associated with the development of colorectal cancer through a multistep process including increasing degrees of dysplasia and DNA-ploidy changes. However, not all UC patients will develop these characteristics even during lifelong disease, and patients may therefore be divided into progressors who develop dysplasia or cancer, and non-progressors who do not exhibit such changes. In the present study, the amount of hTERT, the catalytic subunit of the enzyme telomerase, was estimated by using peroxidase immunohistochemistry (IHC) in a set of progressor and non-progressor UC colectomies. The protein levels in the colonic mucosa of the progressors and non-progressors were compared, and further comparisons between different categories of dysplastic development and to DNA-ploidy status within the progressors were made. Levels of hTERT were elevated in the colonic mucosa of the progressors and non-progressors when compared to non-UC control samples, but no difference was observed between the hTERT levels in the mucosa of progressors and non-progressors. The levels of hTERT associated with levels of Ki67 to a significant degree within the non-progressors. hTERT expression in lesions with DNA-aneuploidy were decreased as compared to diploid lesions, when stratified for different classes of colonic morphology. Our results indicate an association between hTERT protein expression and aneuploidy in UC-progressor colons, and also a possible protective mechanism in the association between hTERT and Ki67, against development of malignant features within the mucosa of a UC-colon.

Daucosterol promotes the proliferation of neural stem cells

Neural stem cells (NSCs) are self-regenerating cells, but their regenerative capacity is limited. The present study was conducted to investigate the effect of daucosterol (a sterolin) on the promotion of NSC proliferation and determine the corresponding molecular mechanism. Results of cell counting kit-8 (CCK-8) assay showed that daucosterol significantly increased the quantity of viable cells and the effectiveness of daucosterol was similar to that of basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF). Flow cytometry detection of CFSE-labeled (CFSE, carboxyfluorescein diacetate succinimidyl ester) NSCs showed that Div Index (or the average number of cell divisions) and % Divided (or the percentage of cells that divided at least once) of the cells were increased, indicating that daucosterol increased the percentage of NSCs re-entering the cell cycle. mRNA microarray analysis showed that 333 genes that are mostly involved in the mitotic cell cycle were up-regulated. By contrast, 627 genes that are mostly involved in differentiation were down-regulated. In particular, insulin-like growth factor I (IGF1) was considered as an important regulatory gene that functionally promoted NSC proliferation, and the increased expression of IGF1 protein was validated by ELISA. In addition, the phosphorylation of AKT was increased, indicating that the proliferation-enhancing activity of daucosterol may be involved in IGF1-AKT pathway. Our study provided information about daucosterol as an efficient and inexpensive growth factor alternative that could be used in clinical medicine and research applications.

Telomere shortening correlates to dysplasia but not to DNA aneuploidy in longstanding ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) is a chronic, inflammatory bowel disease which may lead to dysplasia and adenocarcinoma in patients when long-lasting. Short telomeres have been reported in mucosal cells of UC patients. Telomeres are repetitive base sequences capping the ends of linear chromosomes, and protect them from erosion and subsequent wrongful recombination and end-to-end joining during cell division. Short telomeres are associated with the development of chromosomal instability and aneuploidy, the latter being risk factors for development of dysplasia and cancer. Specifically, the abrupt shortening of one or more telomeres to a critical length, rather than bulk shortening of telomeres, seems to be associated with chromosomal instability.

METHODS

We investigated possible associations between dysplasia, aneuploidy and telomere status in a total of eight lesions from each of ten progressors and four nonprogressors suffering from longstanding UC. We have analyzed mean telomere length by qPCR, as well as the amount of ultra-short telomeres by the Universal STELA method.

RESULTS

An increased amount of ultra-short telomeres, as well as general shortening of mean telomere length are significantly associated with dysplasia in longstanding UC. Furthermore, levels of ultra-short telomeres are also significantly increased in progressors (colons harbouring cancer/dysplasia and/or aneuploidy) compared to nonprogressors (without cancer/dysplasia/aneuploidy), whereas general shortening of telomeres did not show such associations.

CONCLUSIONS

Our data suggest that ultra-short telomeres may be more tightly linked to colorectal carcinogenesis through development of dysplasia in UC than general telomere shortening. Telomere status was not seen to associate with DNA aneuploidy.

Identification of novel compounds that enhance colon cancer cell sensitivity to inflammatory apoptotic ligands

Immune and inflammatory death ligands expressed within neoplastic tissue could potentially target apoptosis to transformed cells. To develop approaches that accentuate the anti-cancer potential of the inflammatory response, the Chembridge DIVERSet (TM) library was screened for compounds that accentuated apoptosis in a strictly TNF-dependent manner. We identified a number of novel compounds with this activity, the most active of these, AK3 and AK10, sensitized colon cancer cells to TNF at 0.5 μM and 2 μM, respectively, without inducing apoptosis on their own. The activity of these compounds was structure-dependent and general, as they accentuated cell death by TNF or Fas ligation in multiple colon cancer cell lines. Both AK3 and AK10 arrested cells in mitosis, with live cell imaging indicating that mitotically arrested cells were the source of apoptotic bodies. AK3 accentuated caspase-8 and caspase-9 activation with little effect on NFκB target gene activation. Enhanced caspase activation corresponded to an increased expression of TNFR1 on the cell surface. To determine the general interplay between mitotic arrest and TNF sensitivity, Aurora kinase (MLN8054 and MLN8237) and PLK1 (BI2536) inhibitors were tested for their ability to sensitize cells to TNF. PLK1 inhibition was particularly effective and influenced TNFR1 surface presentation and caspase cleavage like AK3, even though it arrested mitosis at an earlier stage. We propose that AK3 and AK10 represent a new class of mitotic inhibitor and that selected mitotic inhibitors may be useful for treating colon cancers or earlier lesions that have a high level of inflammatory cell infiltrate.

New insights into the role of BubR1 in mitosis and beyond

BubR1 is a critical component of the spindle assembly checkpoint, the surveillance mechanism that helps maintain the high fidelity of mitotic chromosome segregation by preventing cells from initiating anaphase if one or more kinetochores are not attached to the spindle. BubR1 also helps promote the establishment of stable kinetochore-microtubule attachments during prometaphase. In this chapter, we review the structure, functions, and regulation of BubR1 in these "classical roles" at the kinetochore. We discuss its recruitment to kinetochores, its assembly into the inhibitor of anaphase progression, and the importance of its posttranslational modifications. We also consider the evidence for its participation in other roles beyond mitosis, such as the meiosis-specific processes of recombination and prophase arrest of the first meiotic division, the cellular response to DNA damage, and in the regulation of centrosome and basal body function. Finally, studies are presented linking BubR1 dysfunction or misregulation to aging and human disease, particularly cancer.

Correlation between reduced expression of the spindle checkpoint protein BubR1 and bad prognosis in tonsillar carcinomas

BACKGROUND

Spindle checkpoint proteins such as Mad2 and BubR1 are important for chromosome segregation during mitosis. The aim of the present study was to examine their possible impact on prognosis in tonsillar carcinomas and their relation to clinical variables, the prevalence of human papillomavirus (HPV), p53 status, and Ki-67 positivity.

METHODS

We examined the expression of Mad2 and BubR1 by immunohistochemistry on tissue microarrays from 105 patients with tonsillar carcinomas.

RESULTS

BubR1 and Mad2 were both expressed in tonsillar carcinomas. Expression of BubR1 was a significant prognostic factor in univariate survival analysis. In multivariate analyses, BubR1 was a significant prognostic factor together with stage, age, and HPV status p < .01), whereas Mad2 did not show any significant correlations.

CONCLUSION

We have shown that BubR1 expression is a novel and strong prognostic factor in tonsillar carcinomas, giving additional information to the TNM stage and other known prognostic factors.

Spindle proteins in resected pancreatic head adenocarcinomas: BubR1 is an independent prognostic factor in pancreatobiliary-type tumours

AIMS

Spindle proteins such as Aurora A, Mad2 and BubR1 are important for chromosome segregation during mitosis. Dysfunction of these proteins is implicated in the development of many cancers. The aim was to examine their possible prognostic impact in resected adenocarcinomas in the pancreatic head.

METHODS AND RESULTS

Two hundred and eighteen consecutively resected pancreatobiliary-type (n=145) and intestinal-type (n=73) adenocarcinomas involving the pancreatic head were examined for expression of Aurora A, Mad2 and BubR1 by immunohistochemistry on tissue microarrays. Aurora A (P<0.001) and Mad2 (P=0.003) were expressed more often and at higher levels in intestinal-type compared with pancreatobiliary-type tumours, whereas BubR1 was equally expressed in both histological types. Expression of BubR1, Aurora A and Mad2 was not associated with ploidy status. None of the spindle proteins was significantly associated with prognosis in intestinal-type tumours. In pancreatobiliary-type tumours, any BubR1 expression was sufficient to predict poor prognosis (P=0.006), whereas Aurora A and Mad2 expression was not significantly associated with prognosis (P=0.86 and P= 0.87, respectively). On adjusted Cox regression analysis, BubR1 expression independently predicted poor prognosis [P=0.002; hazard ratio (HR) 1.87, 95% confidence interval (CI) 1.26, 2.79)], particularly in small tumours (P=0.001; HR 2.93, 95% CI 1.53, 5.62).

CONCLUSION

BubR1 expression is a novel, independent adverse prognostic factor after pancreatoduodenectomy of pancreatobiliary-type adenocarcinomas.

Spindle proteins are differentially expressed in the various histological subtypes of testicular germ cell tumors

Background:

Testicular germ cell tumors (TGCTs) are characterized by an aneuploid DNA content. Aberrant expression of spindle proteins such as the Aurora kinases and the spindle checkpoint proteins MAD2 and BUB1B, are thought to contribute to the development of chromosomal instability and DNA aneuploidy in cancer. The importance of these spindle proteins remains unknown in the development of TGCTs, thus we have explored the expression levels of these proteins in normal and malignant testicular tissues.

Materials and Methods:

Using tissue microarrays the expression levels of Aurora kinase A (AURKA), Aurora kinase B (AURKB), BUB1B and MAD2 were measured in normal, preneoplastic and malignant testicular tissues of different histological subtypes from 279 orchidectomy specimens by means of immunohistochemistry.

Results:

All the spindle proteins except for AURKB were expressed in normal testis. Sixty-eight and 36%, respectively, of the primary spermatocytes in the normal testis were positive for BUB1B and MAD2, while only 5% of the cells were positive for AURKA. There was a significantly lower expression of the spindle checkpoint proteins in carcinoma in situ compared to normal testis (P=0.008 and P=0.043 for BUB1B and MAD2, respectively), while the level of AURKA was increased, however, not significantly (P=0.18). The extent of spindle protein expression varied significantly within the different histological subtypes of TGCTs (P<0.001 for AURKB, BUB1B and MAD2, P=0.003 for AURKA). The expression of AURKA was significantly elevated in both non-seminomas (P=0.003) and seminomas (P=0.015). The level of BUB1B was significantly decreased in non-seminomas (P<0.001). A similar tendency was observed for MAD2 (P=0.11).

Conclusions:

In carcinoma in situ of TGCTs the spindle checkpoint proteins MAD2 and BUB1B are significantly less expressed compared to normal testis, while the expression of AURKA is increased. We suggest that these changes may be of importance in the transition from in situ to invasive testicular cancer.

High expression of BUBR1 is one of the factors for inducing DNA aneuploidy and progression in gastric cancer

Gastric cancers show high frequency of DNA aneuploidy, a phenotype of chromosomal instability. It is suggested that the abnormal spindle assembly checkpoint is involved in DNA aneuploidy, but the underlying mechanism is still unclear. We studied the mechanism by assessing the expression of BUBR1 in gastric cancer. The DNA ploidy patterns of 116 gastric cancer samples obtained from the Department of Surgery and Science at Kyushu University Hospital were analyzed. Of those, DNA aneuploidy was seen in 70 (60.3%) cases of gastric cancer. The expression of BUBR1 was studied by immunohistochemistry in 181 gastric cancer samples and by real-time RT-PCR in several gastric cancer cell lines. Ninety-one (50.3%) cases had high expression of BUBR1 and those cases correlated significantly with DNA aneuploidy (P < 0.05). Also high expression of BUBR1 cases had significant correlation with deep invasion, lymph node metastasis, liver metastasis, and poor prognosis. In gastric cancer cell lines, high expression of BUBR1 had a significant relationship with DNA aneuploidy (P < 0.05). Then, gastric cancer cell lines MKN-28 and SNU-1 were transfected with full-length BUBR1 to observe the significance of the change in BUBR1 expression. Enforced expression of BUBR1 resulted in changes to the ploidy pattern and high Ki-67 expression. Collectively, our clinical and in vitro data indicate that high expression of BUBR1 may be one of causative factors for the induction of DNA aneuploidy and progression of gastric cancer.

Loss of hepatocyte-nuclear-factor-4alpha affects colonic ion transport and causes chronic inflammation resembling inflammatory bowel disease in mice

BACKGROUND

Hnf4alpha, an epithelial specific transcriptional regulator, is decreased in inflammatory bowel disease and protects against chemically-induced colitis in mice. However, the precise role of this factor in maintaining normal inflammatory homeostasis of the intestine remains unclear. The aim of this study was to evaluate the sole role of epithelial Hnf4alpha in the maintenance of gut inflammatory homeostasis in mice.

METHODOLOGY/PRINCIPAL FINDINGS

We show here that specific epithelial deletion of Hnf4alpha in mice causes spontaneous chronic intestinal inflammation leading to focal areas of crypt dropout, increased cytokines and chemokines secretion, immune cell infiltrates and crypt hyperplasia. A gene profiling analysis in diseased Hnf4alpha null colon confirms profound genetic changes in cell death and proliferative behaviour related to cancer. Among the genes involved in the immune protection through epithelial barrier function, we identify the ion transporter claudin-15 to be down-modulated early in the colon of Hnf4alpha mutants. This coincides with a significant decrease of mucosal ion transport but not of barrier permeability in young animals prior to the manifestation of the disease. We confirm that claudin-15 is a direct Hnf4alpha gene target in the intestinal epithelial context and is down-modulated in mouse experimental colitis and inflammatory bowel disease.

CONCLUSION

Our results highlight the critical role of Hnf4alpha to maintain intestinal inflammatory homeostasis during mouse adult life and uncover a novel function for Hnf4alpha in the regulation of claudin-15 expression. This establishes Hnf4alpha as a mediator of ion epithelial transport, an important process for the maintenance of gut inflammatory homeostasis.

BubR1 as a prognostic marker for recurrence-free survival rates in epithelial ovarian cancers

BACKGROUND

Epithelial ovarian cancer is one of the most lethal malignancies, and has a high recurrence rate. Thus, prognostic markers for recurrence are crucial for the care of ovarian cancer. As ovarian cancers frequently exhibit chromosome instability, we aimed at assessing the prognostic significance of two key mitotic kinases, BubR1 and Aurora A.

METHODS

We analysed paraffin-embedded tissue sections from 160 ovarian cancer patients whose clinical outcomes had been tracked after first-line treatment.

RESULTS

The median recurrence-free survival in patients with a positive and negative expression of BubR1 was 27 and 83 months, respectively (P<0.001). A positive BubR1 expression was also associated with advanced stage, serous histology and high grade. In contrast, Aurora A immunostaining did not correlate with any of the clinical parameters analysed.

CONCLUSION

BubR1, but not Aurora A, is a prognostic marker for recurrence-free survival rates in epithelial ovarian cancers.

Hydrophobic bile acids, genomic instability, Darwinian selection, and colon carcinogenesis

Sporadic colon cancer is caused predominantly by dietary factors. We have selected bile acids as a focus of this review since high levels of hydrophobic bile acids accompany a Western-style diet, and play a key role in colon carcinogenesis. We describe how bile acid-induced stresses cause cell death in susceptible cells, contribute to genomic instability in surviving cells, impose Darwinian selection on survivors and enhance initiation and progression to colon cancer. The most likely major mechanisms by which hydrophobic bile acids induce stresses on cells (DNA damage, endoplasmic reticulum stress, mitochondrial damage) are described. Persistent exposure of colon epithelial cells to hydrophobic bile acids can result in the activation of pro-survival stress-response pathways, and the modulation of numerous genes/proteins associated with chromosome maintenance and mitosis. The multiple mechanisms by which hydrophobic bile acids contribute to genomic instability are discussed, and include oxidative DNA damage, p53 and other mutations, micronuclei formation and aneuploidy. Since bile acids and oxidative stress decrease DNA repair proteins, an increase in DNA damage and increased genomic instability through this mechanism is also described. This review provides a mechanistic explanation for the important link between a Western-style diet and associated increased levels of colon cancer.

Reduced level of the spindle checkpoint protein BUB1B is associated with aneuploidy in colorectal cancers

OBJECTIVES

The majority of solid human malignancies demonstrate DNA aneuploidy as a consequence of chromosomal instability. We wanted to investigate whether Aurora A, Aurora B, BUB1B and Mad2 were associated with the development of aneuploidy in colorectal adenocarcinomas as suggested by several in vitro studies, and if their protein levels were related to alterations at the corresponding chromosomal loci.

MATERIALS AND METHODS

Expression levels of these spindle proteins were investigated by immunohistochemistry using tissue micro-arrays in a series of DNA aneuploid and diploid colorectal adenocarcinomas previously examined for genomic aberrations by comparative genomic hybridization.

RESULTS

All proteins were overexpressed in malignant tissues compared to controls (P < 0.001 for all). BUB1B level was significantly reduced in aneuploid compared to diploid cancers (P = 0.001), whereas expression of the other proteins was not associated with DNA ploidy status. High levels of Aurora A (P = 0.049) and low levels of Aurora B (P = 0.031) were associated with poor prognosis, but no associations were revealed between protein expression and genomic aberration.

CONCLUSIONS

A significant reduction of BUB1B level was detected in aneuploid compared to diploid colorectal cancers, consistent with earlier studies showing that loss of spindle checkpoint function may be involved in development of DNA aneuploidy. Our data also show that spindle proteins are overexpressed in colorectal cancers, and that expression of the Aurora kinases is associated with prognosis in colorectal cancer.