Identification of The Prognostic Genes For Early Basal-Like Breast Cancer With Weighted Gene Co-Expression Network Analysis

Background: Breast cancer (BC) has become the leading cause of death for women's malignancies and increasingly threatens the health of women worldwide. However, the basal-like BC is lack of effective targeted drugs. Therefore, biomarkers that related to the prognosis of early breast cancer need to be found.Methods: The RNA-seq data of 87 cases of early basal-like BC and 111 cases of normal breast tissue from The Cancer Genome Atlas (TCGA) were explored by Weighted Gene Co-Expression Network Analysis (WGCNA)method and Limma package. Then intersected genes (IGs) were identified and hub genes were selected by Maximal Clique Centrality method. The prognostic effect of the hub genes was also evaluated in early basal-like BC. Results: A total of 601 IGs were identified in this study. APPI network was constructed and top 10 hub genes were selected, namely cyclin B1 (CCNB1), cyclin A2 (CCNA2), cyclin dependent kinase 1 (CDK1), cell division cycle 20 (CDC20), DNA topoisomerase II alpha (TOP2A), BUB1 mitotic checkpoint serine/threonine kinase (BUB1), aurora kinase B (AURKB), cyclin B2 (CCNB2), kinesin family member 11 (KIF11), and assembly factor for spindle microtubules (ASPM). Only AURKB was found to be significant with the overall prognosis of early basal-like BC. The immune cells infiltration analysis displayed that the infiltration numbers of CD4+ T cell and naïve CD8+ T cell were positively correlated with AURKB expression level, while that of naïve B cell and macrophage M2 cell were negatively correlated with AURKB expression level in basal-like BC.Conclusion: AURKB might be a potential prognostic indicator in early basal-like BC.

Prognostic Value of BUB1 for Predicting Non-Muscle-Invasive Bladder Cancer Progression

Non-muscle-invasive bladder cancer (NMIBC) is a common disease with a high recurrence rate requiring lifetime surveillance. Although NMIBC is not life-threatening, it can progress to muscle-invasive bladder cancer (MIBC), a lethal form of the disease. The management of the two diseases differs, and patients with MIBC require aggressive treatments such as chemotherapy and radical cystectomy. NMIBC patients at a high risk of progression benefit from early immediate cystectomy. Thus, identifying concordant markers for accurate risk stratification is critical to predict the prognosis of NMIBC. Candidate genetic biomarkers associated with NMIBC prognosis were screened by RNA-sequencing of 24 tissue samples, including 16 NMIBC and eight normal controls, and by microarray analysis (GSE13507). Lastly, we selected and investigated a mitotic checkpoint serine/threonine kinase, BUB1, that regulates chromosome segregation during the cell cycle. BUB1 gene expression was tested in 86 NMIBC samples and 15 controls by real-time qPCR. The performance of BUB1 as a prognostic biomarker for NMIBC was validated in the internal Chungbuk cohort (GSE13507) and the external UROMOL cohort (E-MTAB-4321). BUB1 expression was higher in NMIBC patients than in normal controls (p < 0.05), and the overexpression of BUB1 was correlated with NMIBC progression (log-rank test, p = 0.007). In in vitro analyses, BUB1 promoted the proliferation of bladder cancer cells by accelerating the G2/M transition of the cell cycle. Conclusively, BUB1 modulates the G2/M transition to promote the proliferation of bladder cancer cells, suggesting that it could serve as a prognostic marker in NMIBC.

Mitotic phosphorylation of tumor suppressor DAB2IP maintains spindle assembly checkpoint and chromosomal stability through activating PLK1-Mps1 signal pathway and stabilizing mitotic checkpoint complex

Chromosomal instability (CIN) is a driving force for cancer development. The most common causes of CIN include the dysregulation of the spindle assembly checkpoint (SAC), which is a surveillance mechanism that prevents premature chromosome separation during mitosis by targeting anaphase-promoting complex/cyclosome (APC/C). DAB2IP is frequently silenced in advanced prostate cancer (PCa) and is associated with aggressive phenotypes of PCa. Our previous study showed that DAB2IP activates PLK1 and functions in mitotic regulation. Here, we report the novel mitotic phosphorylation of DAB2IP by Cdks, which mediates DAB2IP’s interaction with PLK1 and the activation of the PLK1-Mps1 pathway. DAB2IP interacts with Cdc20 in a phosphorylation-independent manner. However, the phosphorylation of DAB2IP inhibits the ubiquitylation of Cdc20 in response to SAC, and blocks the premature release of the APC/C-MCC. The PLK1-Mps1 pathway plays an important role in mitotic checkpoint complex (MCC) assembly. It is likely that DAB2IP acts as a scaffold to aid PLK1-Mps1 in targeting Cdc20. Depletion or loss of the Cdks-mediated phosphorylation of DAB2IP destabilizes the MCC, impairs the SAC, and increases chromosome missegregation and subsequent CIN, thus contributing to tumorigenesis. Collectively, these results demonstrate the mechanism of DAB2IP in SAC regulation and provide a rationale for targeting the SAC to cause lethal CIN against DAB2IP-deficient aggressive PCa, which exhibits a weak SAC.

Targeting the Mitotic Checkpoint in Myeloma with OSU-13, a Novel Mps1/Ttk Inhibitor

Despite recent advances, there is still a lack of treatment options for patients with high-risk multiple myeloma (MM), warranting the need for novel therapeutic targets. Monopolar spindle 1 (Mps1), also known as TTK protein kinase, is localized at the kinetochores and centromeres essential for the mitotic spindle checkpoint and centrosome duplication. In cancer cells, high levels of Mps1 help to support aneuploidy, a common malignant trait. In fact, high MPS1 expression correlates to unfavorable prognosis in colon and breast cancers. Here, we report the importance of Mps1 in MM and perform functional characterization of a novel Mps1 inhibitor, OSU-13. To assess the relevance of Mps1 in MM prognosis, we analyzed the CoMMpass database and examined the association of MPS1 expression with clinical outcome and genetic alterations in MM patients (n=769). Elevated MPS1 expression correlates with decreased overall survival (p-value = 0.0001) and decreased event-free survival (p-value &lt; 0.0001). In addition, MPS1 expression is higher in high-risk MM with specific genetic alterations, such as deletion of 17p (p-value = 0.0003), Myc translocation t(8;14) (p-value = 0.02), and gain of 1q21 (p-value = 0.0001). We therefore compared MPS1 expression in eight different MM cell lines and primary CD138 - and CD138 + cells isolated from bone marrow (BM) of four recently diagnosed, untreated MM patients. Gene expression levels assessed by quantitative qPCR were normalized to 18S mRNA internal control, and relative quantification was performed using the ΔΔCt method. MPS1 expression was higher in all MM cell lines compared to the average expression level in primary CD138 + BM plasma cells, with a minimum of 3.2-fold increase in L363 and a maximum of 16.2-fold increase in MM1S. In addition, MPS1 expression was 2-fold higher in CD138 + MM cells compared to CD138 - counterparts from the BM of the same patient, suggesting its selectivity as a target. Next, we characterized the effects of OSU-13, a novel Mps1 inhibitor. In an Mps1 target engagement assay (NanoBRET™) in HEK293 cells, we measured the relative levels of OSU-13-mediated inhibition of Mps1-NanoLuc binding to a fluorescent tracer in comparison to MM clinical candidates. OSU-13 showed EC 50=10 nM, almost 10-fold lower than other agents tested. Endpoint measurement by MTT (3-[4,5- dimethylthiazol- 2-yl]-2,5-diphenyltetrazolium bromide) assay was used to evaluate cytotoxicity of OSU-13. MM cell lines were treated with increasing doses of OSU-13 for 72h and cell viability was measured. OPM-2 was the most sensitive cell line (IC 50 = 610 nM), followed by H929 (IC 50 = 1440 nM), RPMI-8226 (IC 50 = 4196 nM), and U266 (IC 50 = 5071 nM). To investigate the kinetics and the mechanisms used by OSU-13 to cause cell death, we treated H929 and OPM-2 cell lines with 500 nM of OSU-13 for 24h, 48h, 72h, 96h, and 120h and assessed both Annexin V-FITC and Zombie-Aqua staining by flow cytometry. Treatment with OSU-13 caused an increase in Annexin V staining as early as 24h in H929 (2.1-fold) and OPM-2 (1.6-fold). Maximum increase of apoptotic cells (Annexin V single positive) was observed after 72h, with a 5-fold increase in OPM-2 and 8.6-fold increase in H929 cell line. Cell death peaked at 120h, with Zombie staining 74% of OPM-2 and 60% of H929 cells. The activity of caspases 3/7 was further assessed in H929 myeloma cells at five time points after treatment with different concentrations of OSU-13. Caspases 3/7 activation started after 48h with 500nM OSU-13, and peaked after 72h post-treatment with the same dose, in agreement with the Annexin staining kinetics results. Finally, we evaluated the in vivo effect of OSU-13 in tumor growth in a H929 MM subcutaneous xenograft model in CB.17 SCID mice. Mice were treated with 5 mg/kg or 10 mg/kg daily dose of OSU-13 per oral gavage for 21 days. Treatment with 10 mg/kg daily dose of OSU-13 produced a 22% tumor growth delay (p&lt;0.05). Collectively, we show here that elevated MPS1/TTK expression correlates with poorer prognosis in MM, and OSU-13, a novel Mps1/TTK inhibitor, induces apoptosis and cell death in MM cell lines, and decreases tumor growth in mice containing H929 cell xenografts. Together, our findings reveal that targeting the mitotic checkpoint using OSU-13 is a potential novel strategy, particularly for high risk MM. Disclosures No relevant conflicts of interest to declare.

PRCC reduces the sensitivity of cancer cells to DNA damage by inhibiting JNK and ATM/ATR pathways and results in a poor prognosis in hepatocellular carcinoma

Background and aim The proline rich mitotic checkpoint control factor (PRCC) is involved in the splicing process of pre-mRNA. This study aims to elucidate PRCC molecular function, regulatory mechanism and diagnostic value in hepatocellular carcinoma (HCC). Methods The tissue microarray and serum samples from HCC patients were used to investigate the clinical value of PRCC. The biological function and molecular mechanism of PRCC were demonstrated by cell biology, biochemical and animal experiments. The relationship between PRCC and intratumoral heterogeneity (ITH) was analyzed by bioinformatics. Results PRCC was highly expressed in HCC tissues and related to the poor prognosis of HCC patients, its contents were elevated in the preoperative sera of HCC patients. PRCC exhibited high application potential as a substitute or adjuvant of alpha-fetoprotein (AFP) for clinical diagnosis of HCC. It had no significant effect on the proliferation of cancer cells, but could inhibit spheroid formation and metastasis of HCC cells in vitro and in vivo. The high ectopic expression of PRCC made cancer cells insensitive to DNA damage, and enhanced the heterogeneity of HCC cells by inhibiting the JNK/ATM/ATR/ATF2 axis. The HCC patients with high PRCC expression had high ITH, which corresponded to a short overall survival in patients. Conclusions PRCC has high application potential as a substitute or adjuvant of AFP for clinical diagnosis of HCC. The high ectopic expression of PRCC not only caused HCC cells to resist to cell death induced by DNA damage, but also endowed cancer cells with numerous DNA mutations to become increasingly heterogeneous, finally leading to a poor prognosis in HCC patients. These data suggested PRCC could be a promising therapeutic target in HCC patients.

Hsp90 chaperone code and the tumor suppressor VHL cooperatively regulate the mitotic checkpoint

Heat shock protein-90 (Hsp90) is an essential molecular chaperone in eukaryotes that plays a vital role in protecting and maintaining the functional integrity of deregulated signaling proteins in tumors. We have previously reported that the stability and activity of the mitotic checkpoint kinase Mps1 depend on Hsp90. In turn, Mps1-mediated phosphorylation Hsp90 regulates its chaperone function and is essential for the mitotic arrest. Cdc14-assisted dephosphorylation of Hsp90 is vital for the mitotic exit. Post-translational regulation of Hsp90 function is also known as the Hsp90 “Chaperone Code.” Here, we demonstrate that only the active Mps1 is ubiquitinated on K86, K827, and K848 by the tumor suppressor von Hippel-Lindau (VHL) containing E3 enzyme, in a prolyl hydroxylation-independent manner and degraded in the proteasome. Furthermore, we show that this process regulates cell exit from the mitotic checkpoint. Collectively, our data demonstrates an interplay between the Hsp90 chaperone and VHL degradation machinery in regulating mitosis.

PIGN spatiotemporally regulates the spindle assembly checkpoint proteins in leukemia transformation and progression

Phosphatidylinositol glycan anchor biosynthesis class N (PIGN) has been linked to the suppression of chromosomal instability. The spindle assembly checkpoint complex is responsible for proper chromosome segregation during mitosis to prevent chromosomal instability. In this study, the novel role of PIGN as a regulator of the spindle assembly checkpoint was unveiled in leukemic patient cells and cell lines. Transient downregulation or ablation of PIGN resulted in impaired mitotic checkpoint activation due to the dysregulated expression of spindle assembly checkpoint-related proteins including MAD1, MAD2, BUBR1, and MPS1. Moreover, ectopic overexpression of PIGN restored the expression of MAD2. PIGN regulated the spindle assembly checkpoint by forming a complex with the spindle assembly checkpoint proteins MAD1, MAD2, and the mitotic kinase MPS1. Thus, PIGN could play a vital role in the spindle assembly checkpoint to suppress chromosomal instability associated with leukemic transformation and progression.