Expression of the microtubule-associated protein MAP9/ASAP and its partners AURKA and PLK1 in colorectal and breast cancers

Colon cancer transcriptome

Over the last four decades, methodological innovations have continuously changed transcriptome profiling. It is now feasible to sequence and quantify the transcriptional outputs of individual cells or thousands of samples using RNA sequencing (RNA-seq). These transcriptomes serve as a connection between cellular behaviors and their underlying molecular mechanisms, such as mutations. This relationship, in the context of cancer, provides a chance to unravel tumor complexity and heterogeneity and uncover novel biomarkers or treatment options. Since colon cancer is one of the most frequent malignancies, its prognosis and diagnosis seem to be critical. The transcriptome technology is developing for an earlier and more accurate diagnosis of cancer which can provide better protectivity and prognostic utility to medical teams and patients. A transcriptome is a whole set of expressed coding and non-coding RNAs in an individual or cell population. The cancer transcriptome includes RNA-based changes. The combined genome and transcriptome of a patient may provide a comprehensive picture of their cancer, and this information is beginning to affect treatment decision-making in real-time. A full assessment of the transcriptome of colon (colorectal) cancer has been assessed in this review paper based on risk factors such as age, obesity, gender, alcohol use, race, and also different stages of cancer, as well as non-coding RNAs like circRNAs, miRNAs, lncRNAs, and siRNAs. Similarly, they have been examined independently in the transcriptome study of colon cancer.

AURORA KINASE A and related downstream molecules: A potential network for cancer therapy

Aurora-A kinase (AURKA) belongs to the serine/threonine kinase family specific to cell division. In normal cells, activation of the AURKA protein is essential for regulating chromosomal segregation and centrosome maturation. The physiological concentration of AURKA accumulation has utmost importance during cell division. AURKA starts accumulating during the S phase of the cell cycle, gets functionally activated during the G2/M phase, attaches to the microtubule, and gets degraded during mitotic exit. Overexpression of AURKA could lead to deregulated cell cycle division, which is intrinsic to numerous cancers. Moreover, dysregulated AURKA affects various downstream molecules that aid in cancer pathogenesis. AURKA phosphorylates its substrates, including oncoproteins, transcriptional factors, tumor suppressor proteins, or other kinases central to various oncogenic signaling pathways critical to cancer. Considering the central role of AURKA in cell proliferation and tumorigenesis, targeting AURKA can be a novel alternative to cancer management. Several AURKA inhibitors have shown promising responses against different cancers either as a single agent or combined with various therapies. This chapter briefly discusses the role of AURKA and its downstream molecules in cancer vis-à-vis the role of AURKA inhibitor in chemoprevention.

The Novel RXR Agonist MSU-42011 Differentially Regulates Gene Expression in Mammary Tumors of MMTV-Neu Mice

Retinoid X receptor (RXR) agonists, which activate the RXR nuclear receptor, are effective in multiple preclinical cancer models for both treatment and prevention. While RXR is the direct target of these compounds, the downstream changes in gene expression differ between compounds. RNA sequencing was used to elucidate the effects of the novel RXRα agonist MSU-42011 on the transcriptome in mammary tumors of HER2+ mouse mammary tumor virus (MMTV)-Neu mice. For comparison, mammary tumors treated with the FDA approved RXR agonist bexarotene were also analyzed. Each treatment differentially regulated cancer-relevant gene categories, including focal adhesion, extracellular matrix, and immune pathways. The most prominent genes altered by RXR agonists positively correlate with survival in breast cancer patients. While MSU-42011 and bexarotene act on many common pathways, these experiments highlight the differences in gene expression between these two RXR agonists. MSU-42011 targets immune regulatory and biosynthetic pathways, while bexarotene acts on several proteoglycan and matrix metalloproteinase pathways. Exploration of these differential effects on gene transcription may lead to an increased understanding of the complex biology behind RXR agonists and how the activities of this diverse class of compounds can be utilized to treat cancer.

Phase I study of LZM005 in patients with HER2-positive metastatic breast cancer

The prognosis of human epidermal growth factor receptor 2 (HER2) positive metastatic breast cancer (MBC) remained unsatisfactory currently, more anti-HER2 agents are needed. Here we report a phase I study that evaluated the safety, activity, and biomarkers of LZM005, a HER2 antibody, used as a monotherapy or in combination with trastuzumab plus docetaxel in patients with HER2-positive MBC. From October 2017 to December 2019, 34 patients received LZM005 (14 monotherapy, 20 combination therapy). No DLT was observed. The common adverse events (AEs) in phase Ia included diarrhea (21.4%), infusion reaction (21.4%), and hypertriglyceridemia (21.4%), while those in phase Ib were leukopenia (85.0%), neutropenia (75.0%), anemia (60.0%), diarrhea (60.0%), and rash/pruritus (50.0%). All AEs were manageable. In phase Ia, partial response (PR) was achieved in one case (1/14, overall response rate [ORR]: 7.1%); the disease control rate was 42.90% (6/14). In phase Ib, 11 patients (55.0%) achieved PR, and eight (40.0%) had stable disease. The ORR was 100% (6/6) in trastuzumab-naive and 35.7% (5/14) in trastuzumab-pretreated patients. Biomarker analysis showed that chromatin remodeling genes KMT2B and BRWD1 were associated with better progression-free survival. LZM005 is well tolerated and shows potent activity in patients with HER2-positive MBC.

MAP9 Exhibits Protumor Activities and Immune Escape toward Bladder Cancer by Mediating TGF-β1 Pathway

To investigate more potential targets for the treatment of human bladder cancer, quantitative reverse transcription polymerase chain reaction (qRT-PCR) and high-content screening (HCS) analysis were performed, and microtubule-associated protein 9 (MAP9), which had the strongest proliferation inhibition from 809 downregulated genes, has been selected. MAP9 is responsible for bipolar spindle assembly and is involved in the progression of many types of tumors; however, its role in bladder cancer (BC) remains unknown. Expressive levels of MAP9 in BC tissues were determined through immunohistochemistry, and the clinical significance of MAP9 in BC was analyzed. Short hairpin ribonucleic acid- (ShRNA-) MAP9 was used to construct stable MAP9 knockdown BC cell lines. The proliferative abilities of MAP9 were measured through assays in vivo and in vitro, and the migrated and invasive abilities of MAP9 were analyzed via in vitro experiments. Quantitative reverse transcription PCR, western blotting, coimmunoprecipitation (Co-IP), and rescue assays were used to identify downstream targets of MAP9. MAP9 expression increased in the tumor tissues, and its increased level was negatively correlated with prognosis. Further, the loss of MAP9 caused decreased BC cell proliferation via inducing the growth 1/synthesis (G1/S) cell cycle arrest in vitro and slowed tumor growth in vivo. In addition, MAP9 silencing attenuated BC cell migration and invasion. Moreover, we found that the growth 1/synthesis (G1/S) cell cycle-related genes and the epithelial mesenchymal transition (EMT) marker levels decreased after silencing MAP9. Finally, we found that the transforming growth factor beta 1 (TGF-β1) pathway is activated as a mediator for MAP9 to regulate genes related to the G1/S cell cycle and EMT. MAP9 promotes BC progression and immune escape activity through the TGF-β1 pathway and is a potential novel target for therapies of BC.

Expression of MAP9 in Epstein-Barr virus-associated gastric carcinoma

Epstein-Barr virus (EBV)-associated gastric carcinoma (GC) comprises approximately 9% of all cases of GC. EBV-associated GC (EBVaGC) has characteristic clinicopathological features for a favorable prognosis. Microtubule-associated protein 9 (MAP9) is a cell cycle-associated gene required for bipolar spindle assembly, mitosis progression, and cytokinesis. Nevertheless, to date, there have been no reports on MAP9 function in EBVaGC. In this study, we demonstrated that the mRNA and protein levels of MAP9 were up-regulated in EBV-positive gastric carcinoma cell lines. The positive rate of MAP9 expression in EBVaGC tissues was shown to be significantly higher than that in EBV-negative gastric carcinoma (EBVnGC) tissues. Additionally, the expression of MAP9 was partly increased in EBVnGC cell lines by interfering with DNA methyltransferase 1 (DNMT1) or treated with 5-aza-2'-deoxycytidine. Thus, EBV may regulate MAP9 expression by modifying the methylation of MAP9 CpG islands through DNMT1. By inhibiting the expression of MAP9 with small interfere sequence in the EBV-positive GC cell line GT38 and overexpressing MAP9 in the EBV-negative GC cell line AGS, we demonstrated that MAP9 inhibited the growth and induced apoptosis of EBVaGC cells significantly. In conclusion, our study demonstrated that EBV can up-regulate the expression of MAP9 in EBVaGC, and the methylation of MAP9 CpG islands influences this regulation. And MAP9 acts as a tumor suppressor in the development of EBVaGC.

Microtubule associated protein 9 inhibits liver tumorigenesis by suppressing ERCC3

Background

Chromosomal instability plays an important part in cancer, but its genetic basis in liver tumorigenesis remains largely unclear. We aimed to characterize the mechanistic significance and clinical implication of mitotic regulator microtubule-associated protein 9 (MAP9) in hepatocellular carcinoma (HCC).

Methods

The biological functions of MAP9 were determined by in vitro tumorigenicity assays. Systematic MAP9 knockout mouse (MAP9^∆/∆) and hepatocyte-specific MAP9 knockout mouse (MAP9^∆/∆hep) were generated to confirm the role of MAP9 in HCC. The clinical impact of MAP9 was assessed in primary HCC tissue samples.

Findings

We found that MAP9 was frequently silenced in HCC tissue samples. The transcriptional silence of MAP9 in liver cancer cell lines and tissue samples was mediated by its promoter hypermethylation. MAP9 promoter hypermethylation or downregulation was associated with poor survival and recurrence in patients with HCC. Mechanistically, ectopic expression of MAP9 in LO2 and HepG2 cell lines impaired cell proliferation, colony formation, migration and invasion, and induced cell apoptosis and cycle arrest, whereas knockdown of MAP9 in Miha cell line showed the opposite effects. We found that MAP9^∆/∆ mice spontaneously developed a liver hyperplastic nodule and MAP9^∆/∆hep accelerated diethylnitrosamine-induced HCC formation. The tumour suppressive effect of MAP9 in HCC was mediated by downregulating excision repair cross-complementation group 3 (ERCC3), a nucleotide excision repair gene. Restoration of ERCC3 expression possessed an oncogenic potency and abrogated the tumour suppressive effects of MAP9.

Interpretation

MAP9 is a novel tumour suppressor in HCC by inhibiting ERCC3 expression, and serves as a prognostic factor in HCC patients.

Identification of lung adenocarcinoma biomarkers based on bioinformatic analysis and human samples

Lung adenocarcinoma is one of the most common malignant tumors worldwide. Although efforts have been made to clarify its pathology, the underlying molecular mechanisms of lung adenocarcinoma are still not clear. The microarray datasets GSE75037, GSE63459 and GSE32863 were downloaded from the Gene Expression Omnibus (GEO) database to identify biomarkers for effective lung adenocarcinoma diagnosis and therapy. The differentially expressed genes (DEGs) were identified by GEO2R, and function enrichment analyses were conducted using the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO). The STRING database and Cytoscape software were used to construct and analyze the protein-protein interaction network (PPI). We identified 376 DEGs, consisting of 83 upregulated genes and 293 downregulated genes. Functional and pathway enrichment showed that the DEGs were mainly focused on regulation of cell proliferation, the transforming growth factor β receptor signaling pathway, cell adhesion, biological adhesion, and responses to hormone stimulus. Sixteen hub genes were identified and biological process analysis showed that these 16 hub genes were mainly involved in the M phase, cell cycle phases, the mitotic cell cycle, and nuclear division. We further confirmed the two genes with the highest node degree, DNA topoisomerase IIα (TOP2A) and aurora kinase A (AURKA), in lung adenocarcinoma cell lines and human samples. Both these genes were upregulated and associated with larger tumor size. Upregulation of AURKA in particular, was associated with lymphatic metastasis. In summary, identification of the DEGs and hub genes in our research enables us to elaborate the molecular mechanisms underlying the genesis and progression of lung adenocarcinoma and identify potential targets for the diagnosis and treatment of lung adenocarcinoma.

A Combinatorial MAP Code Dictates Polarized Microtubule Transport

Many eukaryotic cells distribute their intracellular components asymmetrically through regulated active transport driven by molecular motors along microtubule tracks. While intrinsic and extrinsic regulation of motor activity exists, what governs the overall distribution of activated motor-cargo complexes within cells remains unclear. Here, we utilize in vitro reconstitution of purified motor proteins and non-enzymatic microtubule-associated proteins (MAPs) to demonstrate that MAPs exhibit distinct influences on the motility of the three main classes of transport motors: kinesin-1, kinesin-3, and cytoplasmic dynein. Further, we dissect how combinations of MAPs affect motors and unveil MAP9 as a positive modulator of kinesin-3 motility. From these data, we propose a general "MAP code" that has the capacity to strongly bias directed movement along microtubules and helps elucidate the intricate intracellular sorting observed in highly polarized cells such as neurons.

MiR-320a was highly expressed in postmenopausal osteoporosis and acts as a negative regulator in MC3T3E1 cells by reducing MAP9 and inhibiting PI3K/AKT signaling pathway

BACKGROUND

Postmenopausal osteoporosis (PMO), as a frequent disease in postmenopausal women, is mainly caused by the lack of estrogen. MiR-320a has been found to abate osteoblast function and induce oxidative stress before osteoporosis. However, studies on the downstream target gene and related signaling pathway of miR-320a in PMO are still obscure. This study aims to deal with these problems.

METHODS

The expression levels of miR-320a and microtubule-associated protein 9 (MAP9) in patients with osteoporosis were analyzed on the basis of the GEO database. The cells viability was determined by methylthiazolyl tetrazolium bromide (MTT). Flow cytometry and western blot were used to detect the cells apoptosis and the expression of apoptosis-related proteins, respectively. The cells differentiation-related proteins were detected by qRT-PCR and western blot. The interaction between miR-320a and MAP9 was predicted by biological software and verified by dual luciferase reporter assay and rescue assay. The expression levels of PI3K, p-PI3K, AKT and p-AKT in MC3T3-E1 cells were assessed by western blot.

RESULTS

We observed that miR-320a was over-expressed in PMO patients and exhibited inhibitory effects on MC3T3-E1 cells activity and differentiation, as well as promoting effects on MC3T3-E1 cells apoptosis. MAP9 was verified as a target gene of miR-320a and was negatively regulated by miR-320a. Based on the GEO database, MAP9 was found to be lower expressed in PMO patients. Rescue assay demonstrated that down-regulation of MAP9 could alleviate the promoting effects of miR-320a inhibitor on MC3T3-E1 cells activity and differentiation and the inhibitory effects of miR-320a inhibitor on MC3T3-E1 cells apoptosis. Mechanically, miR-320a/MAP9 possibly took part in MC3T3-E1 cells viability, differentiation and apoptosis via mediating PI3K/AKT signaling pathway.

CONCLUSIONS

Our outcomes demonstrated that miR-320a promoted MC3T3-E1 cells apoptosis, suppressed MC3T3-E1 cells viability and differentiation through targeting MAP9 and modulating PI3K/AKT signaling pathway, which provided theoretical support for miR-320a/MAP9 as promising targets for the treatment and prevention of PMO.

Clinical relevance of cytoskeleton associated proteins for ovarian cancer

PURPOSE

Ovarian cancer has a high mortality rate and up to now no reliable molecular prognostic biomarkers have been established. During malignant progression, the cytoskeleton is strongly altered. Hence we analyzed if expression of certain cytoskeleton-associated proteins is correlated with clinical outcome of ovarian cancer patients.

METHODS

First, in silico analysis was performed using the cancer genome atlas (TCGA), the human expression atlas and Pubmed. Selected candidates were validated on 270 ovarian cancer patients by qRT-PCR and/or by western blotting.

RESULTS

In silico analysis revealed that mRNAs of 214 cytoskeleton-associated proteins are detectable in ovarian cancer tissue. Among these, we selected 17 proteins that participate in cancer disease progression and cytoskeleton modulation: KIF14, KIF20A, KIF18A, ASPM, CEP55, DLGAP5, MAP9, EB1, KATNA1, DIAPH1, ANLN, SCIN, CCDC88A, FSCN1, GSN, VASP and CDC42. The first ten candidates interact with microtubules (MTs) and the others bind to actin filaments. Validation on clinical samples of ovarian cancer patients revealed that the expression levels of DIAPH1, EB1, KATNA1, KIF14 and KIF18A significantly correlated with clinical and histological parameters of ovarian cancer. High DIAPH1, EB1, KATNA1 and KIF14 protein levels were associated with increased overall survival (OAS) of ovarian cancer patients, while high DIAPH1 and EB1 protein levels were also associated with low differentiation of respective tumors (G2/3). Moreover, DIAPH1 was the only protein, whose expression significantly correlated with increased recurrence-free interval (RFI).

CONCLUSION

Mainly the expression levels of the MT-associated proteins analyzed in this study, correlated with prolonged survival of ovarian cancer patients. From > 200 genes initially considered, 17 cytoskeletal proteins are involved in cancer progression according to the literature. Among these, four proteins significantly correlated with improved survival of ovarian cancer patients.

Aurora-A Regulates Progression and Metastasis of Colorectal Cancer by Promoting Slug Activity

Epithelial–mesenchymal transition (EMT) is associated with cancer metastasis and poor prognosis, but the exact mechanism has not been clarified. Centrosomal Aurora-A kinase gene is frequently overexpressed in a variety of cancers and plays a pivotal role in the growth and survival of cancer cells. However, its role in colorectal cancer metastasis has not been confirmed. Here we demonstrate that Aurora-A plays a crucial role in the progression and metastasis of colorectal cancer by regulating epithelial–mesenchymal transition. In our study, increased Aurora-A expression was detected in colorectal cancer clinical specimens compared to normal colorectal tissues. Moreover, overexpressed Aurora-A significantly promoted the proliferation, migration, and invasion capacity of colorectal cancer cells and then enhanced metastatic capacity of colorectal cancer in vitro and in vivo and eventually led to poor prognosis. Conversely, silencing Aurora-A expression in colorectal cancer cells decreased the capacity of proliferation, migration, and invasion and further reduced colorectal cancer metastasis. Mechanistically, we found that Slug was involved in Aurora-A–induced migration and invasion of colorectal cancer cells. Silencing Slug expression could block Aurora-A–induced migration, invasion, and metastasis of colorectal cancer cells. Furthermore, the expression of Aurora-A and Slug were positively correlated in colorectal cancer tissues and paired normal colorectal tissue. Taken together, our findings revealed a critical role of Aurora-A in colorectal cancer progression and metastasis by regulating epithelial–mesenchymal transition.

ReMAPping the microtubule landscape: How phosphorylation dictates the activities of microtubule-associated proteins

Classical microtubule-associated proteins (MAPs) were originally identified based on their co-purification with microtubules assembled from mammalian brain lysate. They have since been found to perform a range of functions involved in regulating the dynamics of the microtubule cytoskeleton. Most of these MAPs play integral roles in microtubule organization during neuronal development, microtubule remodeling during neuronal activity, and microtubule stabilization during neuronal maintenance. As a result, mutations in MAPs contribute to neurodevelopmental disorders, psychiatric conditions, and neurodegenerative diseases. MAPs are post-translationally regulated by phosphorylation depending on developmental time point and cellular context. Phosphorylation can affect the microtubule affinity, cellular localization, or overall function of a particular MAP and can thus have profound implications for neuronal health. Here we review MAP1, MAP2, MAP4, MAP6, MAP7, MAP9, tau, and DCX, and how each is regulated by phosphorylation in neuronal physiology and disease. Developmental Dynamics 247:138-155, 2018. © 2017 Wiley Periodicals, Inc.

Integrated diagnostic network construction reveals a 4-gene panel and 5 cancer hallmarks driving breast cancer heterogeneity

Breast cancer encompasses a group of heterogeneous diseases, each associated with distinct clinical implications. Dozens of molecular biomarkers capable of categorizing tumors into clinically relevant subgroups have been proposed which, though considerably contribute in precision medicine, complicate our understandings toward breast cancer subtyping and its clinical translation. To decipher the networking of markers with diagnostic roles on breast carcinomas, we constructed the diagnostic networks by incorporating 6 publically available gene expression datasets with protein interaction data retrieved from BioGRID on previously identified 1015 genes with breast cancer subtyping roles. The Greedy algorithm and mutual information were used to construct the integrated diagnostic network, resulting in 37 genes enclosing 43 interactions. Four genes, FAM134B, KIF2C, ALCAM, KIF1A, were identified having comparable subtyping efficacies with the initial 1015 genes evaluated by hierarchical clustering and cross validations that deploy support vector machine and k nearest neighbor algorithms. Pathway, Gene Ontology, and proliferation marker enrichment analyses collectively suggest 5 primary cancer hallmarks driving breast cancer differentiation, with those contributing to uncontrolled proliferation being the most prominent. Our results propose a 37-gene integrated diagnostic network implicating 5 cancer hallmarks that drives breast cancer heterogeneity and, in particular, a 4-gene panel with clinical diagnostic translation potential.

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.