BuGZ facilitates loading of spindle assembly checkpoint proteins to kinetochores in early mitosis.

BuGZ is a kinetochore component that binds to and stabilizes Bub3, a key player in mitotic spindle assembly checkpoint signaling. Bub3 is required for kinetochore recruitment of Bub1 and BubR1, two proteins that have essential and distinct roles in the checkpoint. Both Bub1 and BubR1 localize to kinetochores through interactions with Bub3, which are mediated through conserved GLEBS domains in both Bub1 and BubR1. BuGZ also has a GLEBS domain, which is required for its kinetochore localization as well, presumably mediated through Bub3 binding. Although much is understood about the requirements for Bub1 and BubR1 interaction with Bub3 and kinetochores, much less is known regarding BuGZ's requirements. Here, we used a series of mutants to demonstrate that BuGZ kinetochore localization requires only its core GLEBS domain, which is distinct from the requirements for both Bub1 and BubR1. Furthermore, we found that the kinetics of Bub1, BubR1, and BuGZ loading to kinetochores differ, with BuGZ localizing prior to BubR1 and Bub1. To better understand how complexes containing Bub3 and its binding partners are loaded to kinetochores, we carried out size-exclusion chromatography and analyzed Bub3-containing complexes from cells under different spindle assembly checkpoint signaling conditions. We found that prior to kinetochore formation, Bub3 is complexed with BuGZ but not Bub1 or BubR1. Our results point to a model in which BuGZ stabilizes Bub3 and promotes Bub3 loading onto kinetochores in early mitosis, which, in turn, facilitates Bub1 and BubR1 kinetochore recruitment and spindle assembly checkpoint signaling.

Prognostic and predictive value of the combination of TOP2A and HER2 in node-negative tumors 2 cm or smaller (T1N0) breast cancer.

BACKGROUND: We aim to evaluate the prognostic and predictive value of TOP2A and HER2 expression in T1N0 breast cancer patients. METHODS: 299 cases with T1N0 breast cancer were obtained from the Oncomine database (Cohort 1) and 963 of T1N0 breast cancer patients from Sun Yat-sen Memorial Hospital (Cohort 2) were retrospectively enrolled. Kaplan-Meier product was applied to estimate survival curve. Cox proportional hazard models was used to identify prognostic factors. We used PSM (propensity score matching) to balance clinicopathologic characteristics among four groups of different HER2/TOP2A status. Survival between groups and chemotherapy regimens were analyzed, before and after PSM. RESULTS: In Cohort 1, we found that the group with HER2+ and higher expression of TOP2A mRNA was associated with poor breast cancer-specific survival (BCSS) compared to the group of HER2- with lower expression of TOP2A mRNA. In Cohort 2, HER2+ patients with higher TOP2A protein expression had greater risk of recurrence and distant recurrence compared to HER2- patients with lower expression of TOP2A protein. Among the patients who developed both HER2+ and higher expression of TOP2A protein and received chemotherapy, patients who received an anthracycline-based regimen had a significantly better recurrence-free survival (RFS) than those with a non-anthracycline-based regime. CONCLUSION: Patients with both HER2+ and high expression level of TOP2A protein predicts poor prognosis in T1N0 breast cancer patients. Patients with double positive for TOP2A protein and HER2 may benefit from anthracycline-based regimens.

DEK Is a Potential Biomarker Associated with Malignant Phenotype in Gastric Cancer Tissues and Plasma.

Gastric cancer (GC) is the second most widespread cause of cancer-related mortality worldwide. The discovery of novel biomarkers of oncoproteins can facilitate the development of therapeutic strategies for GC treatment. In this study, we identified novel biomarkers by integrating isobaric tags for relative and absolute quantitation (iTRAQ), a human plasma proteome database, and public Oncomine datasets to search for aberrantly expressed oncogene-associated proteins in GC tissues and plasma. One of the most significantly upregulated biomarkers, DEK, was selected and its expression validated. Our immunohistochemistry (IHC) (n = 92) and quantitative real-time polymerase chain reaction (qRT-PCR) (n = 72) analyses disclosed a marked increase in DEK expression in tumor tissue, compared with paired nontumor mucosa. Importantly, significantly higher preoperative plasma DEK levels were detected in GC patients than in healthy controls via enzyme-linked immunosorbent assay (ELISA). In clinicopathological analysis, higher expression of DEK in both tissue and plasma was significantly associated with advanced stage and poorer survival outcomes of GC patients. Data from receiver operating characteristic (ROC) curve analysis disclosed a better diagnostic accuracy of plasma DEK than carcinoembryonic antigen (CEA), carbohydrate antigen 19.9 (CA 19.9), and C-reactive protein (CRP), highlighting its potential as an effective plasma biomarker for GC. Plasma DEK is also more sensitive in tumor detection than the other three biomarkers. Knockdown of DEK resulted in inhibition of GC cell migration via a mechanism involving modulation of matrix metalloproteinase MMP-2/MMP-9 level and vice versa. Our results collectively support plasma DEK as a useful biomarker for making diagnosis and prognosis of GC patients.

Markers of proliferation and invasiveness in somatotropinomas.

Introduction In the search for markers of invasiveness of pituitary adenomas, we studied the expression of Ki-67 antigen, TOPO 2A (topoisomerase 2 alpha), AIP (Aryl Hydrocarbon Receptor-Interacting Protein) and VEGF (Vascular Endothelial Growth Factor) in somatotropinomas. Material and Methods We retrospectively studied a group of 31 patients who underwent pituitary tumour surgery. Expression of Ki-67, TOPO 2A, AIP and VEGF in surgical specimens was determined by immunohistochemistry. Relations between quantitatively determined markers and clinical symptoms, tumour features, and MR imaging, were analysed. Acromegaly was confirmed by hormonal tests in all patients studied. Local invasiveness (cavernous sinus penetration, optic chiasm compression or suprasellar extension) was observed in 18/31 patients (58,1%). Results Ki-67 was expressed in 77.4%, TOPO 2A in 87.1%, AIP in 83.8%, and VEGF in 87.1% of 31 cases of somatropinoma. Median values of Ki-67, TOPO 2A, AIP and cytoplasmic VEGF indices were 1.2% [IQR=2.2], 1.5% [IQR=1.6], 21.26% [IQR=20.1] and 20.4% [IQR=15.4], respectively. Ki-67, TOPO 2A, AIP and VEGF expression was not correlated with age nor with patient gender (p > 0.05). Only Ki-67 and TOPO 2A correlated with tumour size (for Ki-67: r=0.42, p=0.025; for TOPO 2A: r=0.53, p=0.003). Ki-67 and TOPO 2A levels were significantly higher in invasive compared to noninvasive somatropinomas (Ki67 mean values: 1.85±1.33% vs. 0.95±1.07%, p=0.024; TOPO 2A mean values: 2.19±1.63% vs. 1.45±1.23%, , p=0.011). Conclusions Ki-67, TOPO 2A, AIP and VEGF were expressed in over 70% of all somatotropinomas. Only Ki-67 and TOPO 2A expression correlated with tumour size and tumour invasiveness.

Expression of p53 and selected proliferative markers (Ki-67, MCM3, PCNA, and topoisomerase IIα) in borderline ovarian tumors: Correlation with clinicopathological features.

BACKGROUND: The expression of p53 has been studied not only in primary human ovarian carcinomas, but also in borderline ovarian tumors, however, the results were discordant. Expression patterns of proteins involved in cell proliferation and apoptosis have been investigated in various human neoplasms, including female genital tract neoplasms. OBJECTIVE: The aim of this investigation was to assess the staining pattern and immunolocalization of p53 and selected proliferative markers (Ki-67, MCM3, PCNA, and topoisomerase IIα) in borderline ovarian tumors (BOTs). DESIGN: The study group consisted of 42 women who underwent pelvic surgery between 2006-2015. The median patients' age was 46 years. The immunoperoxidase technique was employed using antibodies against p53, Ki-67, MCM3, PCNA, and topoisomerase IIα. RESULTS: For p53, nuclear expression was observed in BOTs, however, cytoplasmatic immunoreactivity was also detected. Altogether, 25 (60%) tumors demonstrated positive p53 immunostaining, including overexpression found in 6 (14%). There were no significant differences in p53 expression between subgroups of clinicopathological variables. Immunoexpression of Ki-67, MCM3, PCNA, and topoisomerase IIα was nuclear. Ki-67 expression was positive in 12 (29%) cases and there was a trend towards a relationship between patients' age and Ki-67 staining (P=0.08). Interestingly, a significantly higher Ki-67 expression was found in tumors of ≥10 cm in diameter compared to smaller tumors (P=0.008). MCM3 expression was detected in 38 (90%) tumors, and PCNA expression in 28 (67%), yet none of clinicopathological factors was related to them. Topoisomerase IIα expression was present in 14 (33%) cases and, interestingly, its significantly higher expression was observed in BOTs of ≥10 cm in diameter compared to smaller tumors (P=0.008). Moreover, Spearman's correlation revealed highly significant positive associations between Ki-67 and topoisomerase IIα (R=0.403, P=0.008) and Ki-67 and MCM3 (R=0.469, P=0.001). CONCLUSIONS: We report a high positive immunostaining rate for p53, suggesting a role of TP53 alterations in the development of BOTs in humans. The new finding of higher topoisomerase IIα immunostaining positivity in BOTs of ≥10 cm may be clinically relevant and requires further studies on larger patient groups.

[Dectection of G3BP and CD44v6 in the tissues of laryngeal squamous cell carcinoma and their clinical significance].

Objective To study the expressions of RNA-binding Ras-GAP SH3 binding protein (G3BP) and tumor stem cell marker CD44v6 in laryngeal squamous cell carcinoma and their correlations with angiogenesis. Methods We collected the cancer tissues and corresponding paracancerous tissues from 56 patients with laryngeal squamous cell carcinoma. The expressions of G3BP and CD44v6 proteins were detected by Western blotting in cancer tissues and corresponding paracancerous tissues; the expressions of G3BP, CD44v6 and vascular endothelial growth factor A (VEGF-A) were tested by immunohistochemistry. Thereafter, we compared the positive expression rates of G3BP and CD44v6 between in cancer tissues and in normal tissues, analyzed the correlations between the expressions of G3BP, CD44v6 and the laryngeal squamous cell carcinoma features as well as their correlations with microvessel density (MVD) that was determined by FVIIIAg immunohistochemistry. Results Western blotting showed that the expressions of G3BP and CD44v6 proteins in the laryngeal squamous cell carcinoma were higher than those in the paracancerous tissues. Immunohistochemistry showed that compared with the paracancerous tissues, G3BP, CD44v6 and VEGF-A expressions (the positive rates are 58.9%, 53.6%, 46.4%, respectively) were higher in cancer tissues. The positive rates of G3BP and CD44v6 in cancer tissues were related with the clinical stage, recurrence or metastasis, and lymph node metastasis of laryngeal squamous cell carcinoma, but had nothing to do with patients' age and tumor size. Pearson correlation analysis showed the expressions of both G3BP and CD44v6 were positively correlated with VEGF-A (r=0.741, r=0.756). MVD values were significantly higher in the G3BP and CD44v6 positive cases than in paracancerous tissues, but there was no difference in MVD between those without G3BP and CD44v6 positive expressions and the paracancerous tissues. Conclusion The positive expression rates of G3BP and CD44v6 in laryngeal squamous cell carcinoma tissues are very high, and they have a close relationship with the clinical prognosis. They may raise the VEGF-A expression so as to promote angiogenesis, and then accelerate the development of the laryngeal squamous cell carcinoma.