HMMR acts in the PLK1-dependent spindle positioning pathway and supports neural development

Integrated single-cell transcriptomic analyses identify a novel lineage plasticity-related cancer cell type involved in prostate cancer progression

BACKGROUND

Cancer cell plasticity is the ability of neoplastic cells to alter their identity and acquire new biological properties under microenvironmental pressures. In prostate cancer (PCa), lineage plasticity often results in therapy resistance and trans-differentiation to neuroendocrine (NE) lineage. However, identifying the cancer cells harboring lineage plasticity-related status remains challenging.

METHODS

Based on 13 multi-center human PCa bulk transcriptomic cohorts (samples = 3314) and 9 bulk transcriptomic datasets derived from PCa experimental models, we established an integrated lineage plasticity-related gene signature, termed LPSig. Leveraging this gene signature, AUCell enrichment analysis was applied to identify the cell population with high lineage plasticity from a comprehensive single-cell RNA-sequencing (scRNA-seq) meta-atlas assembled by us, which consisted of 10 public human PCa scRNA-seq datasets (samples = 93, cells = 222,529). Moreover, additional scRNA-seq dataset of human PCa, multiplex immunohistochemistry staining for human PCa tissues, in vitro and in vivo functional experiments, as well as qPCR and Western blot analyses were employed to validate our findings.

FINDINGS

We found that LPSig could finely capture the dynamics of tumor lineage plasticity throughout the progression of PCa, accurately estimating the status of lineage plasticity. Based on LPSig, we identified a previously undefined minority population of lineage plasticity-related PCa cells (LPCs) from the human PCa scRNA-seq meta-atlas assembled by this study. Furthermore, in-depth dissection revealed pivotal roles of LPCs in trans-differentiation, tumor recurrence, and poor patient survival during PCa progression. Furthermore, we identified HMMR as a representative cell surface marker for LPCs, which was validated using additional scRNA-seq datasets and multiplexed immunohistochemistry. Moreover, HMMR was transcriptionally inhibited by androgen receptor (AR), and was required for the aggressive adenocarcinoma features and NE phenotype.

INTERPRETATION

Our study uncovers a novel population of lineage plasticity-related cells with low AR activity, stemness-like traits, and elevated HMMR expression, that may facilitate poor prognosis in PCa.

FUNDING

This work was supported by National Key R&D Program of China (2022YFA0807000), National Natural Science Foundation of China (82160584), Advanced Prostate Cancer Diagnosis and Treatment Technology Innovation Team of Kunming Medical University (CXTD202216), and Reserve Talents of Young and Middle-aged Academic Leaders in Yunnan Province (202105AC160013).

Genetic Markers of Spina Bifida in an Indian Cohort

Objective

To identify the genetic markers of spina bifida through a systematic survey of the exome in an Indian cohort.

Materials and Methods

Three consecutive patients (P1: 1 year, male; P2: 2.8 years, male; and P3: 10 years, female) with spina bifida (lumbosacral meningomyelocele) underwent whole-exome sequencing (libraries: SureSelect Human All Exon V8; sequencing: 2 * 150 bp paired-end run, 100×) with NovaSeq 6000. Data analysis was performed using SMART-One™ (secondary analysis) and SMARTer™ (tertiary analysis) for automated quality check, alignment (GRCh38/hg38), variant calling, annotation (ClinVar, OMIM, avsnp150, 1000 Genomes v5b, ExAC v0.3, gnomAD v4.0, and esp6500vi2all v0.0.25), v0.0.25), interpretation. The pathogenic and likely pathogenic (ClinVar/ InterVar), non-synonymous, exonic markers (read depth ≥ 5) were matched with the Familial Neural Tube Defects (Version 1.10) panel (FNTD panel).

Results

Pathogenic variants overlapping with the FNTD panel were MTRR, CC2D2A, and ZIC2 in P1 and P2, TGIF1 in P1 only, and none in P3. Novel pathogenic/likely pathogenic variants common to all three patients were PRUNE1, PKD1, PDZD2, and DAB2 in the homozygous state as well as in the heterozygous state, PLK1 and NLGN2. The possible role of such markers in etiopathogenesis was explored through a literatur search.

Conclusions

The genetic landscape of the spina bifida in an Indian cohort is diverse compared to that reported from other parts of the world. A comprehensive catalog of single-nucleotide variants in the etiopathogenesis of the spina bifida on a background of the Familial Neural Tube Defects Panel has been generated.

The non-mitotic role of HMMR in regulating the localization of TPX2 and the dynamics of microtubules in neurons

A functional nervous system is built upon the proper morphogenesis of neurons to establish the intricate connection between them. The microtubule cytoskeleton is known to play various essential roles in this morphogenetic process. While many microtubule-associated proteins (MAPs) have been demonstrated to participate in neuronal morphogenesis, the function of many more remains to be determined. This study focuses on a MAP called HMMR in mice, which was originally identified as a hyaluronan binding protein and later found to possess microtubule and centrosome binding capacity. HMMR exhibits high abundance on neuronal microtubules and altering the level of HMMR significantly affects the morphology of neurons. Instead of confining to the centrosome(s) like cells in mitosis, HMMR localizes to microtubules along axons and dendrites. Furthermore, transiently expressing HMMR enhances the stability of neuronal microtubules and increases the formation frequency of growing microtubules along the neurites. HMMR regulates the microtubule localization of a non-centrosomal microtubule nucleator TPX2 along the neurite, offering an explanation for how HMMR contributes to the promotion of growing microtubules. This study sheds light on how cells utilize proteins involved in mitosis for non-mitotic functions.

Coupled scRNA-seq and Bulk-seq reveal the role of HMMR in hepatocellular carcinoma

Background

Hyaluronan-mediated motility receptor (HMMR) is overexpressed in multiple carcinomas and influences the development and treatment of several cancers. However, its role in hepatocellular carcinoma (HCC) remains unclear.

Methods

The "limma" and "GSVA" packages in R were used to perform differential expression analysis and to assess the activity of signalling pathways, respectively. InferCNV was used to infer copy number variation (CNV) for each hepatocyte and "CellChat" was used to analyse intercellular communication networks. Recursive partitioning analysis (RPA) was used to re-stage HCC patients. The IC50 values of various drugs were evaluated using the "pRRophetic" package. In addition, quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to confirm HMMR expression in an HCC tissue microarray. Flow cytometry (FCM) and cloning, Edu and wound healing assays were used to explore the capacity of HMMR to regulate HCC tumour.

Results

Multiple cohort studies and qRT-PCR demonstrated that HMMR was overexpressed in HCC tissue compared with normal tissue. In addition, HMMR had excellent diagnostic performance. HMMR knockdown inhibited the proliferation and migration of HCC cells in vitro. Moreover, high HMMR expression was associated with "G2M checkpoint" and "E2F targets" in bulk RNA and scRNA-seq, and FCM confirmed that HMMR could regulate the cell cycle. In addition, HMMR was involved in the regulation of the tumour immune microenvironment via immune cell infiltration and intercellular interactions. Furthermore, HMMR was positively associated with genomic heterogeneity with patients with high HMMR expression potentially benefitting more from immunotherapy. Moreover, HMMR was associated with poor prognosis in patients with HCC and the re-staging by recursive partitioning analysis (RPA) gave a good prognosis prediction value and could guide chemotherapy and targeted therapy.

Conclusion

The results of the present study show that HMMR could play a role in the diagnosis, prognosis, and treatments of patients with HCC based on bulk RNA-seq and scRAN-seq analyses and is a promising molecular marker for HCC.

Single-cell multi-omics profiling of human preimplantation embryos identifies cytoskeletal defects during embryonic arrest

Human in vitro fertilized embryos exhibit low developmental capabilities, and the mechanisms that underlie embryonic arrest remain unclear. Here using a single-cell multi-omics sequencing approach, we simultaneously analysed alterations in the transcriptome, chromatin accessibility and the DNA methylome in human embryonic arrest due to unexplained reasons. Arrested embryos displayed transcriptome disorders, including a distorted microtubule cytoskeleton, increased genomic instability and impaired glycolysis, which were coordinated with multiple epigenetic reprogramming defects. We identified Aurora A kinase (AURKA) repression as a cause of embryonic arrest. Mechanistically, arrested embryos induced through AURKA inhibition resembled the reprogramming abnormalities of natural embryonic arrest in terms of the transcriptome, the DNA methylome, chromatin accessibility and H3K4me3 modifications. Mitosis-independent sequential activation of the zygotic genome in arrested embryos showed that YY1 contributed to human major zygotic genome activation. Collectively, our study decodes the reprogramming abnormalities and mechanisms of human embryonic arrest and the key regulators of zygotic genome activation.

Effect of Aurora kinase B on polyploidy and decidualization in mouse uterus

RESEARCH QUESTION

Decidualization is critical to the establishment of mouse normal pregnancy. The fibroblast-like stromal cells in the process form polyploid multinucleated cells. Aurora kinase B (Aurora B) has previously been shown to regulate polyploidy in various cells. However, whether Aurora B regulates the formation of decidual cell polyploidization and its regulatory mechanisms remain poorly understood.

DESIGN

Establish decidualization model of mouse primary endometrial stromal cells in vitro. Construct pseudopregnancy mouse models and delayed-activation mouse models. Detect Aurora B and polyploidization related genes in mouse uteri treated by Aurora B specific inhibitor Barasertib and CPT.

RESULTS

In this study, we found that Aurora B was strongly expressed in endometrial stromal cells after implantation. Additionally, Aurora B was remarkably up regulated in the stromal cells of oil-induced deciduomoa and in vitro decidualization. As an Aurora B specific inhibitor, Barasertib significantly inhibits the mRNA expression of Prl8a2, a marker of mouse decidualization. Furthermore, the protein levels of p-Plk1, Survivin and p-Cdk1 were inhibited by Barasertib. CPT-induced DNA damage suppressed Aurkb (encodes Aurora B) expression, thus resulting in polyploidization.

CONCLUSION

Our data shows that Aurora B is expressed in decidual stromal cells of implantation sites and plays a key role for mouse decidualization. The protein of Plk1, Survivn, and Cdk1 may participate in formation of decidual cell polyploidization during mouse decidualization.

HMMR associates with immune infiltrates and acts as a prognostic biomaker in lung adenocarcinoma

BACKGROUND

To explore the expression of hyaluronan mediated motility receptor (HMMR) in lung adenocarcinoma (LUAD) and its relationship with clinicopathological features and tumor-infiltrating is not clear.

METHODS

The expression of HMMR in Cancer Cell Line Encyclopedia (CCLE) and The Cancer Genome Atlas (TCGA)-LUAD. TCGA was employed to examine the relationship between the clinicopathological characteristics and HMMR expression and the LUAD patients' prognosis. Tumor Immune Estimation Resource (TIMER)database was employed to analyze the relationship between immune infiltration and HMMR. Gene Set Enrichment Analysis was explored through gene enrichment. Gene Expression Omnibus (GEO) data and our hospital data were utilized to confirm the findings.

RESULTS

The expression level of HMMR in lung adenocarcinoma tissue and cells was greater than that in the normal group, which was linked to clinical stage, smoking history, and recurrence, and could increase the progression or recurrence of LUAD. Patients in the pathological grade had a significant expression of HMMR in moderately differentiated LUAD tissues. In addition, HMMR has an impact on LUAD patients' overall survival rate [P = 9.5e-06; hazard ratio (HR) = 2]. The level of HMMR expression in LUAD was significantly linked to neutrophils, CD8+T, and CD4+T cells. TMB analysis showed that HMMR could also affect the tumor microenvironment in LUAD. HMMR might be employed as an independent predictive biomarker of LUAD, according to a multivariate COX regression analysis. The findings of GSEA analysis showed that the samples with high HMMR expression levels were rich in cell cycle, cell metabolism, and DNA replication. The analysis results of GSE31210 data are basically consistent with those of TCGA-LUAD.

CONCLUSIONS

It is suggested that HMMR has an effect on the occurrence and development of lung adenocarcinoma. Besides, HMMR is also linked to the level of immune infiltration of neutrophils, CD8+T cells, and CD4+T cells and LUAD patients' prognosis. HMMR was suggested to be utilized as a biomarker or therapeutic target to judge the prognosis and immune infiltration of LUAD.

Development and validation of a combined metabolism and immune prognostic model in lung adenocarcinoma

Background

Tumor metabolism and immune response can affect the biological behavior of tumor cells. There is an obvious relationship between glycolysis and immune response. However, the association between metabolism and immune response and prognosis in lung adenocarcinoma (LUAD) has not yet been examined in a comprehensive and detailed manner. The establishment of reliable models for predicting the prognosis of LUAD based on glycolysis ability and immune status is still highly anticipated.

Methods

The expression of genes were obtained from online databases, and the differentially expressed genes in LUAD tissues and adjacent tissues were identified. We used LUAD samples in The Cancer Genome Atlas (TCGA) database as training set and the Gene Expression Omnibus (GEO) databases as validation sets. The best predictive model was constructed using least absolute selection and shrinkage operator (LASSO) regression and Cox regression. The receiver operator characteristic (ROC) curve is used to verify the accuracy of the model. The expression status of the Glycolysis-related genes (GRGs) and the status of the immune cells in LUCD patients were further analyzed. The protein levels of the 3 identified genes were then tested in LUAD patients.

Results

We identified 3 GRGs and immune-related genes (i.e., fibroblast growth factor 2, hyaluronan-mediated motor receptor, and nuclear receptor 0B2) and constructed a stable comprehensive index of glycolysis and immunity (CIGI) prediction model. The validation results for this CIGI model were quite stable across different datasets and patient subgroups and the CIGI score can be included as an independent prognostic factor for LUAD patients. The area under the curve (AUC) values of 1-, 3- and 5-year of the finally established nomogram model are 0.767, 0.735 and 0.769. Further analysis showed that LUAD patients in the low-risk group had lower levels of glycolytic gene expression than those in the high-risk group and exhibited an immunosuppressed state. Finally, hyaluronan-mediated motor receptor may play a role in inhibiting cancer, while fibroblast growth factor 2 and nuclear receptor 0B2 may play roles in promoting cancer.

Conclusions

In this study, we established a new prognostic prediction model for LUAD patients that combines glycolysis ability and immune status.

Genetic interaction between PLK1 and downstream MCPH proteins in the control of centrosome asymmetry and cell fate during neural progenitor division

Alteration of centrosome function and dynamics results in major defects during chromosome segregation and is associated with primary autosomal microcephaly (MCPH). Despite the knowledge accumulated in the last few years, why some centrosomal defects specifically affect neural progenitors is not clear. We describe here that the centrosomal kinase PLK1 controls centrosome asymmetry and cell fate in neural progenitors during development. Gain- or loss-of-function mutations in Plk1, as well as deficiencies in the MCPH genes Cdk5rap2 (MCPH3) and Cep135 (MCPH8), lead to abnormal asymmetry in the centrosomes carrying the mother and daughter centriole in neural progenitors. However, whereas loss of MCPH proteins leads to increased centrosome asymmetry and microcephaly, deficient PLK1 activity results in reduced asymmetry and increased expansion of neural progenitors and cortical growth during mid-gestation. The combination of PLK1 and MCPH mutations results in increased microcephaly accompanied by more aggressive centrosomal and mitotic abnormalities. In addition to highlighting the delicate balance in the level and activity of centrosomal regulators, these data suggest that human PLK1, which maps to 16p12.1, may contribute to the neurodevelopmental defects associated with 16p11.2-p12.2 microdeletions and microduplications in children with developmental delay and dysmorphic features.

Pathogenic BRCA1 variants disrupt PLK1-regulation of mitotic spindle orientation

Preneoplastic mammary tissues from human female BRCA1 mutation carriers, or Brca1-mutant mice, display unexplained abnormalities in luminal differentiation. We now study the division characteristics of human mammary cells purified from female BRCA1 mutation carriers or non-carrier donors. We show primary BRCA1 mutant/+ cells exhibit defective BRCA1 localization, high radiosensitivity and an accelerated entry into cell division, but fail to orient their cell division axis. We also analyse 15 genetically-edited BRCA1 mutant/+ human mammary cell-lines and find that cells carrying pathogenic BRCA1 mutations acquire an analogous defect in their division axis accompanied by deficient expression of features of mature luminal cells. Importantly, these alterations are independent of accumulated DNA damage, and specifically dependent on elevated PLK1 activity induced by reduced BRCA1 function. This essential PLK1-mediated role of BRCA1 in controlling the cell division axis provides insight into the phenotypes expressed during BRCA1 tumorigenesis.

Modification of BRCA1-associated breast cancer risk by HMMR overexpression

Breast cancer risk for carriers of BRCA1 pathological variants is modified by genetic factors. Genetic variation in HMMR may contribute to this effect. However, the impact of risk modifiers on cancer biology remains undetermined and the biological basis of increased risk is poorly understood. Here, we depict an interplay of molecular, cellular, and tissue microenvironment alterations that increase BRCA1-associated breast cancer risk. Analysis of genome-wide association results suggests that diverse biological processes, including links to BRCA1-HMMR profiles, influence risk. HMMR overexpression in mouse mammary epithelium increases Brca1-mutant tumorigenesis by modulating the cancer cell phenotype and tumor microenvironment. Elevated HMMR activates AURKA and reduces ARPC2 localization in the mitotic cell cortex, which is correlated with micronucleation and activation of cGAS-STING and non-canonical NF-κB signaling. The initial tumorigenic events are genomic instability, epithelial-to-mesenchymal transition, and tissue infiltration of tumor-associated macrophages. The findings reveal a biological foundation for increased risk of BRCA1-associated breast cancer.

Primary Cilia and Centrosomes in Neocortex Development

During mammalian brain development, neural stem and progenitor cells generate the neurons for the six-layered neocortex. The proliferative capacity of the different types of progenitor cells within the germinal zones of the developing neocortex is a major determinant for the number of neurons generated. Furthermore, the various modes of progenitor cell divisions, for which the orientation of the mitotic spindle of progenitor cells has a pivotal role, are a key parameter to ensure the appropriate size and proper cytoarchitecture of the neocortex. Here, we review the roles of primary cilia and centrosomes of progenitor cells in these processes during neocortical development. We specifically focus on the apical progenitor cells in the ventricular zone. In particular, we address the alternating, dual role of the mother centriole (i) as a component of one of the spindle poles during mitosis, and (ii) as the basal body of the primary cilium in interphase, which is pivotal for the fate of apical progenitor cells and their proliferative capacity. We also discuss the interactions of these organelles with the microtubule and actin cytoskeleton, and with junctional complexes. Centriolar appendages have a specific role in this interaction with the cell cortex and the plasma membrane. Another topic of this review is the specific molecular composition of the ciliary membrane and the membrane vesicle traffic to the primary cilium of apical progenitors, which underlie the ciliary signaling during neocortical development; this signaling itself, however, is not covered in depth here. We also discuss the recently emerging evidence regarding the composition and roles of primary cilia and centrosomes in basal progenitors, a class of progenitors thought to be of particular importance for neocortex expansion in development and evolution. While the tight interplay between primary cilia and centrosomes makes it difficult to allocate independent roles to either organelle, mutations in genes encoding ciliary and/or centrosome proteins indicate that both are necessary for the formation of a properly sized and functioning neocortex during development. Human neocortical malformations, like microcephaly, underpin the importance of primary cilia/centrosome-related processes in neocortical development and provide fundamental insight into the underlying mechanisms involved.

Effects of Aurora kinase A on mouse decidualization via Stat3-plk1-cdk1 pathway

BACKGROUND

Decidualization is essential to the successful pregnancy in mice. The molecular mechanisms and effects of Aurora kinase A (Aurora A) remain poorly understood during pregnancy. This study is the first to investigate the expression and role of Aurora A during mouse decidualization.

METHODS

Quantitative real time polymerase chain reaction, western blotting and in situ hybridization were used to determine the expression of Aurora A in mouse uteri. Aurora A activity was inhibited by Aurora A inhibitor to explore the role of Aurora A on decidualization via regulating the Aurora A/Stat3/Plk1/Cdk1 signaling pathway.

RESULTS

Aurora A was strongly expressed at implantation sites compared with inter-implantation sites. Furthermore, Aurora A was also significantly increased in oil-induced deciduoma compared with control. Both Aurora A mRNA and protein were significantly increased under in vitro decidualization. Under in vitro decidualization, Prl8a2, a marker of mouse decidualization, was significantly decreased by TC-S 7010, an Aurora A inhibitor. Additionally, Prl8a2 was reduced by Stat3 inhibitor, Plk1 inhibitor and Cdk1 inhibitor, respectively. Moreover, the protein levels of p-Stat3, p-Plk1 and p-Cdk1 were suppressed by TC-S 7010. The protein levels of p-Stat3, p-Plk1 and p-Cdk1 were also suppressed by S3I-201, a Stat3 inhibitor). SBE 13 HCl (Plk1 inhibitor) could reduce the protein levels of p-Plk1 and p-Cdk1. Collectively, Aurora A could regulate Stat3/Plk1/Cdk1 signaling pathway.

CONCLUSION

Our study shows that Aurora A is expressed in decidual cells and should be important for mouse decidualization. Aurora A/Stat3/Plk1/Cdk1 signaling pathway may be involved in mouse decidualization.

Comprehensive Bioinformatics Analysis to Identify the Gene HMMR Associated With Lung Adenocarcinoma Prognosis and Its Mechanism of Action in Multiple Cancers

Background

Lung cancer is the third most frequently diagnosed cancer in the world, with lung adenocarcinoma (LUAD) as the most common pathological type. But studies on the predictive effect of a single gene on LUAD are limited. We aimed to discover new predictive markers for LUAD.

Methods

Differentially high-expressed genes at each stage were obtained from the TCGA and GTEx databases. The functions of these genes were investigated through GO enrichment and KEGG pathway analyses. Then, the key genes were selected by applying whole gene overall survival time. The expression of the key gene was studied in LUAD, and survival analysis was performed using Kaplan-Meier mapper, followed by univariate and multifactorial COX analysis. Finally, the gene expression and its prognostic significance in the pan-cancer were examined.

Results

A total of 10,106 DEGs were obtained from the two datasets. The top 266 differentially upregulated genes intersected with the top 1,497 overall survival-related genes, and 87 key genes were identified. High-expressed HMMR was associated with a poor prognosis of LUAD. Univariate and multifactorial Cox analysis showed that HMMR was an independent prognostic factor for LUAD patients. A high HMMR expression was strongly associated with the overall survival (OS) and disease-specific survival (DSS) in 11 cancer types and with poorer OS, DSS, and PFI in 10 cancer types.

Conclusion

HMMR may be an independent prognostic indicator and an important biomarker in diagnosing and predicting the survival of LUAD patients. Also, HMMR may be a key predictor of a variety of cancers.

High levels of truncated RHAMM cooperate with dysfunctional p53 to accelerate the progression of pancreatic cancer

Pancreatic cancer has the lowest survival rate out of all types of cancer. Pancreatic cancer patients are often diagnosed at advanced stages, hence an urgent need for a better therapeutic development of this devastating disease. Receptor for hyaluronan-mediated motility (RHAMM), not expressed in adult normal pancreas, has been suggested as a prognostic factor and a potential therapeutic target for pancreatic ductal adenocarcinoma (PDAC) and pancreatic neuroendocrine tumor (PNET). In this study, we initially sought to determine whether genetic deletion of RHAMM would slow down pancreatic cancer progression using Rhamm^-/- mice. However, we found that Rhamm^-/- mice expressed a truncated HMMR^Δexon8-16 protein at higher abundance levels than wild-type RHAMM. While HMMR^Δexon8-16 did not enable malignant progression of pancreatic intraepithelial neoplasia in p48-Cre; LSL-KRAS^G12D mice, it accelerated the formation of invasive PDAC and shortened the survival of p48-Cre; LSL-KRAS^G12D mice with heterozygous p53 knockout. Kras^G12D PDAC mice with homozygous p53 knockout mice died around 10 weeks, and the effect of HMMR^Δexon8-16 was not apparent in these short lifespan mice. In addition, HMMR^Δexon8-16 shortened the survival of PNET-bearing RIP-Tag mice, which had inactivated p53. In our analysis of TCGA dataset, pancreatic cancer patients with mutant TP53 or loss of one copy of TP53 had higher RHAMM expression, which, combined, predicted worse outcomes. Taken together, by collaborating with dysfunctional p53, high levels of HMMR^Δexon8-16 , which lacks the centrosome targeting domain and degrons for interaction with the Anaphase-Promoting Complex (APC), accelerated pancreatic cancer progression.

Expression of the Receptor for Hyaluronic Acid-Mediated Motility (RHAMM) in Endometrial Cancer is Associated With Adverse Histologic Parameters and Tumor Progression

Endometrial cancer is one of the most common gynecologic malignancies worldwide. Only 2 agents have been approved by Food and Drug Administration for endometrial cancer since 1971. There is a need to identify molecular targets to treat advanced endometrial cancer. The receptor for hyaluronic acid-mediated motility (RHAMM) is upregulated in various types of cancer. Here, we aimed to determine the clinical significance of RHAMM expression in endometrial cancer. Two hundred twenty-five cases of endometrial cancer, including serous and endometrioid types, and 8 cases of normal endometrium were used for studying RHAMM protein levels. The Cancer Genome Atlas database was also queried for RHAMM mRNA expression in endometrial cancer. Increased expression of RHAMM protein was seen in endometrial cancer compared with no or weak expression in normal endometrium. RHAMM expression positively correlated with tumor grade. RHAMM expression was significantly increased in endometrial serous carcinomas, which are high-grade, aggressive types of endometrial cancer, compared with the relatively less aggressive endometrioid carcinomas. RHAMM expression also correlated with the presence of lymphovascular invasion. RHAMM mRNA expression correlated with decreased survival in The Cancer Genome Atlas cohort. Therefore, increased RHAMM expression in endometrial cancer is associated with high-grade tumors and is indicative of more aggressive behavior. These findings suggest RHAMM as a prognostic factor in endometrial cancer and as a potential therapeutic target in advanced endometrial cancer for future studies.

ceRNA network development and tumor-infiltrating immune cell analysis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is among the primary causes of cancer deaths globally. Despite efforts to understand liver cancer, its high morbidity and mortality remain high. Herein, we constructed two nomograms based on competing endogenous RNA (ceRNA) networks and invading immune cells to describe the molecular mechanisms along with the clinical prognosis of HCC patients. RNA maps of tumors and normal samples were downloaded from The Cancer Genome Atlas database. HTseq counts and fragments per megapons per thousand bases were read from 421 samples, including 371 tumor samples and 50 normal samples. We established a ceRNA network based on differential gene expression in normal versus tumor subjects. CIBERSORT was employed to differentiate 22 immune cell types according to tumor transcriptomes. Kaplan-Meier along with Cox proportional hazard analyses were employed to determine the prognosis-linked factors. Nomograms were constructed based on prognostic immune cells and ceRNAs. We employed Receiver operating characteristic (ROC) and calibration curve analyses to estimate these nomogram. The difference analysis found 2028 messenger RNAs (mRNAs), 128 micro RNAs (miRNAs), and 136 long non-coding RNAs (lncRNAs) to be significantly differentially expressed in tumor samples relative to normal samples. We set up a ceRNA network containing 21 protein-coding mRNAs, 12 miRNAs, and 3 lncRNAs. In Kaplan-Meier analysis, 21 of the 36 ceRNAs were considered significant. Of the 22 cell types, resting dendritic cell levels were markedly different in tumor samples versus normal controls. Calibration and ROC curve analysis of the ceRNA network, as well as immune infiltration of tumor showed restful accuracy (3-year survival area under curve (AUC): 0.691, 5-year survival AUC: 0.700; 3-year survival AUC: 0.674, 5-year survival AUC: 0.694). Our data suggest that Tregs, CD4 T cells, mast cells, SNHG1, HMMR and hsa-miR-421 are associated with HCC based on ceRNA immune cells co-expression patterns. On the basis of ceRNA network modeling and immune cell infiltration analysis, our study offers an effective bioinformatics strategy for studying HCC molecular mechanisms and prognosis.

Identification of the HMMR Gene as a Diagnostic and Prognostic Biomarker in Hepatocellular Carcinoma Based on Integrated Bioinformatics Analysis

BACKGROUND

We aimed to investigate the expression of the hyaluronan-mediated motility receptor (HMMR) gene in hepatocellular carcinoma (HCC) and nonneoplastic tissues and to investigate the diagnostic and prognostic value of HMMR.

METHOD

With the reuse of the publicly available The Cancer Genome Atlas (TCGA) data, 374 HCC patients and 50 nonneoplastic tissues were used to investigate the diagnostic and prognostic values of HMMR genes by receiver operating characteristic (ROC) curve analysis and survival analysis. All patients were divided into low- and high-expression groups based on the median value of HMMR expression level. Univariate and multivariate Cox regression analysis were used to identify prognostic factors. Gene set enrichment analysis (GSEA) was performed to explore the potential mechanism of the HMMR genes involved in HCC. The diagnostic and prognostic values were further validated in an external cohort from the International Cancer Genome Consortium (ICGC).

RESULTS

HMMR mRNA expression was significantly elevated in HCC tissues compared with that in normal tissues from both TCGA and the ICGC cohorts (all P values <0.001). Increased HMMR expression was significantly associated with histologic grade, pathological stage, and survival status (all P values <0.05). The area under the ROC curve for HMMR expression in HCC and normal tissues was 0.969 (95% CI: 0.948-0.983) in the TCGA cohort and 0.956 (95% CI: 0.932-0.973) in the ICGC cohort. Patients with high HMMR expression had a poor prognosis than patients with low expression group in both cohorts (all P < 0.001). Univariate and multivariate analysis also showed that HMMR is an independent predictor factor associated with overall survival in both cohorts (all P values <0.001). GSEA showed that genes upregulated in the high-HMMR HCC subgroup were mainly significantly enriched in the cell cycle pathway, pathways in cancer, and P53 signaling pathway.

CONCLUSION

HMMR is expressed at high levels in HCC. HMMR overexpression may be an unfavorable prognostic factor for HCC.

Hyaluronan-mediated motility receptor expression functions as a prognostic biomarker in uterine carcinosarcoma based on bioinformatics analysis

OBJECTIVE

Uterine carcinosarcoma (UCS) is a rare, aggressive tumour with a high metastasis rate and poor prognosis. This study aimed to explore potential key genes associated with the prognosis of UCS.

METHODS

Transcriptional expression data were downloaded from the Gene Expression Profiling Interactive Analysis database and differentially expressed genes (DEGs) were subjected to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses using Metascape. A protein-protein interaction network was constructed using the STRING website and Cytoscape software, and the top 30 genes obtained through the Maximal Clique Centrality algorithm were selected as hub genes. These hub genes were validated by clinicopathological and sequencing data for 56 patients with UCS from The Cancer Genome Atlas database.

RESULTS

A total of 1894 DEGs were identified, and the top 30 genes were considered as hub genes. Hyaluronan-mediated motility receptor (HMMR) expression was significantly higher in UCS tissues compared with normal tissues, and elevated expression of HMMR was identified as an independent prognostic factor for shorter survival in patients with UCS.

CONCLUSIONS

These results suggest that HMMR may be a potential biomarker for predicting the prognosis of patients with UCS.

Hyaluronan-Mediated Motility Receptor Governs Chromosome Segregation by Regulating Microtubules Sliding Within the Bridging Fiber

Accurate segregation of chromosomes during anaphase relies on the central spindle and its regulators. A newly raised concept of the central spindle, the bridging fiber, shows that sliding of antiparallel microtubules (MTs) within the bridging fiber promotes chromosome segregation. However, the regulators of the bridging fiber and its regulatory mechanism on MTs sliding remain largely unknown. In this study, the non-motor microtubule-associated protein, hyaluronan-mediated motility receptor (HMMR), is identified as a novel regulator of the bridging fiber. It then identifies that HMMR regulates MTs sliding within the bridging fiber by cooperating with its binding partner HSET. By utilizing a laser-based cell ablation system and photoactivation approach, the study's results reveal that depletion of HMMR causes an inhibitory effect on MTs sliding within the bridging fiber and disrupts the forced uniformity on the kinetochore-attached microtubules-formed fibers (k-fibers). These are created by suppressing the dynamics of HSET, which functions in transiting the force from sliding of bridging MTs to the k-fiber. This study sheds new light on the novel regulatory mechanism of MTs sliding within the bridging fiber by HMMR and HSET and uncovers the role of HMMR in chromosome segregation during anaphase.

A choreography of centrosomal mRNAs reveals a conserved localization mechanism involving active polysome transport

Local translation allows for a spatial control of gene expression. Here, we use high-throughput smFISH to screen centrosomal protein-coding genes, and we describe 8 human mRNAs accumulating at centrosomes. These mRNAs localize at different stages during cell cycle with a remarkable choreography, indicating a finely regulated translational program at centrosomes. Interestingly, drug treatments and reporter analyses reveal a common translation-dependent localization mechanism requiring the nascent protein. Using ASPM and NUMA1 as models, single mRNA and polysome imaging reveals active movements of endogenous polysomes towards the centrosome at the onset of mitosis, when these mRNAs start localizing. ASPM polysomes associate with microtubules and localize by either motor-driven transport or microtubule pulling. Remarkably, the Drosophila orthologs of the human centrosomal mRNAs also localize to centrosomes and also require translation. These data identify a conserved family of centrosomal mRNAs that localize by active polysome transport mediated by nascent proteins.

Centrosomes function as microtubule organizing centers where several mRNAs accumulate. By employing high-throughput single molecule FISH screening, the authors discover that 8 human mRNAs localize to centrosomes with unique cell cycle dependent patterns using an active polysome targeting mechanism.

Non-classical role of Galectin-3 in cancer progression: translocation to nucleus by carbohydrate-recognition independent manner

Galectin-3 is a carbohydrate-binding protein and regulates diverse functions, including cell proliferation and differentiation, mRNA splicing, apoptosis induction, immune surveillance and inflammation, cell adhesion, angiogenesis, and cancer-cell metastasis. Galectin-3 is also recommended as a diagnostic or prognostic biomarker of various diseases, including heart disease, kidney disease, and cancer. Galectin-3 exists as a cytosol, is secreted in extracellular spaces on cells, and is also detected in nuclei. It has been found that galectin-3 has different functions in cellular localization: (i) Extracellular galectin-3 mediates cell attachment and detachment. (ii) cytosolic galectin-3 regulates cell survival by blocking the intrinsic apoptotic pathway, and (iii) nuclear galectin-3 supports the ability of the transcriptional factor for target gene expression. In this review, we focused on the role of galectin-3 on translocation from cytosol to nucleus, because it happens in a way independent of carbohydrate recognition and accelerates cancer progression. We also suggested here that intracellular galecin-3 could be a potent therapeutic target in cancer therapy. [BMB Reports 2020; 53(4): 173-180].

Prognostic implication of glycolysis related gene signature in non-small cell lung cancer

Abnormal glycolysis is one of the hallmarks of cancer and plays an important role in its development. This study was devoted to identify glycolysis related genes as prognostic biomarkers for non-small cell lung cancer (NSCLC). The mRNA expression profile and clinical follow-up data were obtained using The Cancer Genome Atlas (TCGA) database. The validation set was obtained by bootstrap method of random repeated sampling. A total of 200 glycolysis-related genes were obtained from Gene Set Enrichment Analysis (GSEA) and 46 genes were significantly associated with overall survival (OS). Five genes (PKP2, LDHA, HMMR, COL5A1 and B3GNT3) were eventually identified to calculate risk score of NSCLC patients.

The univariate and multivariate Cox regression analysis indicated that the risk score was an independent prognostic factor (training set: HR=2.126, 95% CI [1.605, 2.815], p<0.001; validation set: HR=2.298, 95%CI [1.450, 3.640], p<0.001). Patients assigned to the high-risk group were associated with poor OS compared with patients in the low-risk group (training set: P=7.946e-06; validation set: P=6.368e-07). Receiver operating characteristic (ROC) curve and stratification analysis also demonstrated the potential prognostic performance. In conclusion, we constructed a novel glycolysis related risk signature which might contribute to predicting the prognosis of NSCLC.

The scrambled story between hyaluronan and glioblastoma

Advances in cancer biology are revealing the importance of the cancer cell microenvironment on tumorigenesis and cancer progression. Hyaluronan (HA), the main glycosaminoglycan in the extracellular matrix, has been associated with the progression of glioblastoma (GBM), the most frequent and lethal primary tumor in the central nervous system, for several decades. However, the mechanisms by which HA impacts GBM properties and processes have been difficult to elucidate. In this review, we provide a comprehensive assessment of the current knowledge on HA's effects on GBM biology, introducing its primary receptors CD44 and RHAMM and the plethora of relevant downstream signaling pathways that can scramble efforts to directly link HA activity to biological outcomes. We consider the complexities of studying an extracellular polymer and the different strategies used to try to capture its function, including 2D and 3D in vitro studies, patient samples, and in vivo models. Given that HA affects not only migration and invasion, but also cell proliferation, adherence, and chemoresistance, we highlight the potential role of HA as a therapeutic target. Finally, we review the different existing approaches to diminish its protumor effects, such as the use of 4-methylumbelliferone, HA oligomers, and hyaluronidases and encourage further research along these lines in order to improve the survival and quality of life of GBM patients.

Centrosomes in mitotic spindle assembly and orientation

The centrosome is present in most animal cells and functions as the major microtubule-organizing center to ensure faithful chromosome segregation during cell division. As cells transition from interphase to mitosis, the duplicated centrosomes separate and move to opposite sides of the cell where the spindle assembles. Centrosomes not only nucleate but also organize microtubules of the mitotic spindle. The mitotic spindle is anchored to the cell cortex by the astral microtubules emanating from the centrosomes. Proper orientation of the mitotic spindle is essential for correct cell division. Centrosome-localized polo-like kinase Plk1 has been linked to regulation of proper spindle orientation. A number of proteins including MISP and NuMA have been implicated in the Plk1-mediated spindle orientation pathway.

Oleate acid-stimulated HMMR expression by CEBPα is associated with nonalcoholic steatohepatitis and hepatocellular carcinoma

Non-alcoholic steatohepatitis (NASH) is a type of nonalcoholic fatty liver disease and has become a major risk factor for hepatocellular carcinoma (HCC). However, the underlying pathophysiological mechanisms are still elusive. Here, we identify hyaluronan-mediated motility receptor (HMMR) as a critical gene associated with NASH/HCC by combination of bioinformatic analysis and functional experiments. Analysis of differentially expressed genes (DEGs) between normal controls and NASH/HCC identified 5 hub genes (HMMR, UBE2T, TYMS, PTTG1 and GINS2). Based on the common DEGs, analyses of univariate and multivariate Cox regression and the area under the curve (AUC) value of the receiver operating characteristic (ROC) indicate that HMMR is the most significant gene associated with NASH/HCC among five hub genes. Oleate acid (OA), one of fatty acids that induce cellular adipogenesis, stimulates HMMR expression via CCAAT/enhancer-binding protein α (CEBPα). CEBPα increases the expression of HMMR through binding to its promoter. HMMR promotes HCC cell proliferation in vitro via activation of G1/S and G2/M checkpoint transitions, concomitant with a marked increase of the positive cell cycle regulators, including cyclin D1, cyclin E, and cyclin B1. Knockdown of HMMR suppresses HCC tumor growth in nude mice. Our study identifies an important role of HMMR in NASH/HCC, and suggests that HMMR may be a useful target for therapy and prognostic prediction of NASH/HCC patients.

PP2A--B55γ counteracts Cdk1 and regulates proper spindle orientation through the cortical dynein adaptor NuMA

Proper orientation of the mitotic spindle is critical for accurate development and morphogenesis. In human cells, spindle orientation is regulated by the evolutionarily conserved protein NuMA, which interacts with dynein and enriches it at the cell cortex. Pulling forces generated by cortical dynein orient the mitotic spindle. Cdk1-mediated phosphorylation of NuMA at threonine 2055 (T2055) negatively regulates its cortical localization. Thus, only NuMA not phosphorylated at T2055 localizes at the cell cortex. However, the identity and the mechanism of action of the phosphatase complex involved in T2055 dephosphorylation remains elusive. Here, we characterized the PPP2CA-B55γ (PPP2R2C)-PPP2R1B complex that counteracts Cdk1 to orchestrate cortical NuMA for proper spindle orientation. In vitro reconstitution experiments revealed that this complex is sufficient for T2055 dephosphorylation. Importantly, we identified polybasic residues in NuMA that are critical for T2055 dephosphorylation, and for maintaining appropriate cortical NuMA levels for accurate spindle elongation. Furthermore, we found that Cdk1-mediated phosphorylation and PP2A-B55γ-mediated dephosphorylation at T2055 are reversible events. Altogether, this study uncovers a novel mechanism by which Cdk1 and its counteracting PP2A-B55γ complex orchestrate spatiotemporal levels of cortical force generators for flawless mitosis.

CYCLIN-B1/2 and -D1 act in opposition to coordinate cortical progenitor self-renewal and lineage commitment

The sequential generation of layer-specific cortical neurons requires radial glia cells (RGCs) to precisely balance self-renewal and lineage commitment. While specific cell-cycle phases have been associated with these decisions, the mechanisms linking the cell-cycle machinery to cell-fate commitment remain obscure. Using single-cell RNA-sequencing, we find that the strongest transcriptional signature defining multipotent RGCs is that of G2/M-phase, and particularly CYCLIN-B1/2, while lineage-committed progenitors are enriched in G1/S-phase genes, including CYCLIN-D1. These data also reveal cell-surface markers that allow us to isolate RGCs and lineage-committed progenitors, and functionally confirm the relationship between cell-cycle phase enrichment and cell fate competence. Finally, we use cortical electroporation to demonstrate that CYCLIN-B1/2 cooperate with CDK1 to maintain uncommitted RGCs by activating the NOTCH pathway, and that CYCLIN-D1 promotes differentiation. Thus, this work establishes that cell-cycle phase-specific regulators act in opposition to coordinate the self-renewal and lineage commitment of RGCs via core stem cell regulatory pathways.

Hyaluronan Mediated Motility Receptor (HMMR) Encodes an Evolutionarily Conserved Homeostasis, Mitosis, and Meiosis Regulator Rather than a Hyaluronan Receptor

Hyaluronan is an extracellular matrix component that absorbs water in tissues and engages cell surface receptors, like Cluster of Differentiation 44 (CD44), to promote cellular growth and movement. Consequently, CD44 demarks stem cells in normal tissues and tumor-initiating cells isolated from neoplastic tissues. Hyaluronan mediated motility receptor (HMMR, also known as RHAMM) is another one of few defined hyaluronan receptors. HMMR is also associated with neoplastic processes and its role in cancer progression is often attributed to hyaluronan-mediated signaling. But, HMMR is an intracellular, microtubule-associated, spindle assembly factor that localizes protein complexes to augment the activities of mitotic kinases, like polo-like kinase 1 and Aurora kinase A, and control dynein and kinesin motor activities. Expression of HMMR is elevated in cells prior to and during mitosis and tissues with detectable HMMR expression tend to be highly proliferative, including neoplastic tissues. Moreover, HMMR is a breast cancer susceptibility gene product. Here, we briefly review the associations between HMMR and tumorigenesis as well as the structure and evolution of HMMR, which identifies Hmmr-like gene products in several insect species that do not produce hyaluronan. This review supports the designation of HMMR as a homeostasis, mitosis, and meiosis regulator, and clarifies how its dysfunction may promote the tumorigenic process and cancer progression.

A Model of Differential Mammary Growth Initiation by Stat3 and Asymmetric Integrin-α6 Inheritance

Multiple cancer-related genes both promote and paradoxically suppress growth initiation, depending on the cell context. We discover an explanation for how this occurs for one such protein, Stat3, based on asymmetric cell division. Here, we show that Stat3, by Stathmin/PLK-1, regulates mitotic spindle orientation, and we use it to create and test a model for differential growth initiation. We demonstrate that Integrin-α6 is polarized and required for mammary growth initiation. Spindles orient relative to polar Integrin-α6, dividing perpendicularly in normal cells and parallel in tumor-derived cells, resulting in asymmetric or symmetric Integrin-α6 inheritance, respectively. Stat3 inhibition randomizes spindle orientation, which promotes normal growth initiation while reducing tumor-derived growth initiation. Lipid raft disruption depolarizes Integrin-α6, inducing spindle-orientation-independent Integrin-α6 inheritance. Stat3 inhibition no longer affects the growth of these cells, suggesting Stat3 acts through the regulation of spindle orientation to control growth initiation.

Mitotic kinase anchoring proteins: the navigators of cell division

The coordinated activities of many protein kinases, acting on multiple protein substrates, ensures the error-free progression through mitosis of eukaryotic cells. Enormous research effort has thus been devoted to studying the roles and regulation of these mitotic kinases, and to the identification of their physiological substrates. Central for the timely deployment of specific protein kinases to their appropriate substrates during the cell division cycle are the many anchoring proteins, which serve critical regulatory roles. Through direct association, anchoring proteins are capable of modulating the catalytic activity and/or sub-cellular distribution of the mitotic kinases they associate with. The key roles of some anchoring proteins in cell division are well-established, whilst others are still being unearthed. Here, we review the current knowledge on anchoring proteins for some mitotic kinases, and highlight how targeting anchoring proteins for inhibition, instead of the mitotic kinases themselves, could be advantageous for disrupting the cell division cycle.

Galectin-3 Interacts with C/EBPβ and Upregulates Hyaluronan-Mediated Motility Receptor Expression in Gastric Cancer

The hyaluronan-mediated motility receptor (HMMR) is overexpressed in gastric cancer; however, the apparent role of HMMR has not been well defined owing to lack of detailed studies on gastric tumorigenesis. Therefore, we elucidated the functional and regulatory mechanisms of HMMR in gastric cancer. Using publicly available data, we confirmed HMMR overexpression in patients with gastric cancer. HMMR silencing decreased proliferation, migration, and invasion of gastric cancer cells, whereas HMMR overexpression reversed these effects. A gastric cancer xenograft mouse model showed statistically significant inhibition of tumor growth upon HMMR depletion. Previous data from cDNA microarray showed reduced HMMR expression upon inhibition of galectin-3. However, overexpression of galectin-3 increased HMMR expression, cell proliferation, and motility in gastric cancer cells, whereas HMMR silencing blocked these effects. Interestingly, galectin-3 interacted directly with C/EBPβ and bound to HMMR promoter to drive its transcription, and gastric cancer cell proliferation and motility. Altogether, high expression of HMMR promoted gastric cancer cell proliferation and motility and could be a prognostic factor in gastric cancer. In addition, HMMR expression was regulated by the interaction between C/EBPβ and galectin-3. Therefore, targeting HMMR along with galectin-3 and C/EBPβ complex could be a potential treatment strategy for inhibiting gastric cancer progression and metastasis. IMPLICATIONS: This study provides evidence that galectin-3 interacts with C/EBPβ in gastric cancer, and galectin-3 and C/EBPβ complex promotes gastric cancer cell progression and motility through upregulating HMMR expression.

FAM83D directs protein kinase CK1α to the mitotic spindle for proper spindle positioning

The concerted action of many protein kinases helps orchestrate the error-free progression through mitosis of mammalian cells. The roles and regulation of some prominent mitotic kinases, such as cyclin-dependent kinases, are well established. However, these and other known mitotic kinases alone cannot account for the extent of protein phosphorylation that has been reported during mammalian mitosis. Here we demonstrate that CK1α, of the casein kinase 1 family of protein kinases, localises to the spindle and is required for proper spindle positioning and timely cell division. CK1α is recruited to the spindle by FAM83D, and cells devoid of FAM83D, or those harbouring CK1α-binding-deficient FAM83DF283A/F283A knockin mutations, display pronounced spindle positioning defects, and a prolonged mitosis. Restoring FAM83D at the endogenous locus in FAM83D-/- cells, or artificially delivering CK1α to the spindle in FAM83DF283A/F283A cells, rescues these defects. These findings implicate CK1α as new mitotic kinase that orchestrates the kinetics and orientation of cell division.

Hyaluronan and Its Interactions With Immune Cells in the Healthy and Inflamed Lung

Hyaluronan is a hygroscopic glycosaminoglycan that contributes to both extracellular and pericellular matrices. While the production of hyaluronan is essential for mammalian development, less is known about its interaction and function with immune cells. Here we review what is known about hyaluronan in the lung and how it impacts immune cells, both at homeostasis and during lung inflammation and fibrosis. In the healthy lung, alveolar macrophages provide the first line of defense and play important roles in immunosurveillance and lipid surfactant homeostasis. Alveolar macrophages are surrounded by a coat of hyaluronan that is bound by CD44, a major hyaluronan receptor on immune cells, and this interaction contributes to their survival and the maintenance of normal alveolar macrophage numbers. Alveolar macrophages are conditioned by the alveolar environment to be immunosuppressive, and can phagocytose particulates without alerting an immune response. However, during acute lung infection or injury, an inflammatory immune response is triggered. Hyaluronan levels in the lung are rapidly increased and peak with maximum leukocyte infiltration, suggesting a role for hyaluronan in facilitating leukocyte access to the injury site. Hyaluronan can also be bound by hyaladherins (hyaluronan binding proteins), which create a provisional matrix to facilitate tissue repair. During the subsequent remodeling process hyaluronan concentrations decline and levels return to baseline as homeostasis is restored. In chronic lung diseases, the inflammatory and/or repair phases persist, leading to sustained high levels of hyaluronan, accumulation of associated immune cells and an inability to resolve the inflammatory response.

Plk1 regulates spindle orientation by phosphorylating NuMA in human cells

Proper orientation of the mitotic spindle defines the correct division plane and is essential for accurate cell division and development. In metazoans, an evolutionarily conserved complex comprising of NuMA/LGN/Gαi regulates proper orientation of the mitotic spindle by orchestrating cortical dynein levels during metaphase. However, the molecular mechanisms that modulate the spatiotemporal dynamics of this complex during mitosis remain elusive. Here, we report that acute inactivation of Polo-like kinase 1 (Plk1) during metaphase enriches cortical levels of dynein/NuMA/LGN and thus influences spindle orientation. We establish that this impact of Plk1 on cortical levels of dynein/NuMA/LGN is through NuMA, but not via dynein/LGN. Moreover, we reveal that Plk1 inhibition alters the dynamic behavior of NuMA at the cell cortex. We further show that Plk1 directly interacts and phosphorylates NuMA. Notably, NuMA-phosphorylation by Plk1 impacts its cortical localization, and this is needed for precise spindle orientation during metaphase. Overall, our finding connects spindle-pole pool of Plk1 with cortical NuMA and answers a long-standing puzzle about how spindle-pole Plk1 gradient dictates proper spindle orientation for error-free mitosis.

Expression-based analyses indicate a central role for hypoxia in driving tumor plasticity through microenvironment remodeling and chromosomal instability

Can transcriptomic alterations drive the evolution of tumors? We asked if changes in gene expression found in all patients arise earlier in tumor development and can be relevant to tumor progression. Our analyses of non-mutated genes from the non-amplified regions of the genome of 158 triple-negative breast cancer (TNBC) cases identified 219 exclusively expression-altered (EEA) genes that may play important role in TNBC. Phylogenetic analyses of these genes predict a "punctuated burst" of multiple gene upregulation events occurring at early stages of tumor development, followed by minimal subsequent changes later in tumor progression. Remarkably, this punctuated burst of expressional changes is instigated by hypoxia-related molecular events, predominantly in two groups of genes that control chromosomal instability (CIN) and those that remodel tumor microenvironment (TME). We conclude that alterations in the transcriptome are not stochastic and that early-stage hypoxia induces CIN and TME remodeling to permit further tumor evolution.

The Receptor for Hyaluronan-Mediated Motility (CD168) promotes inflammation and fibrosis after acute lung injury

Acute lung injury results in early inflammation and respiratory distress, and later fibrosis. The glycosaminoglycan hyaluronan (HA) and the Receptor for Hyaluronan-Mediated Motility (RHAMM, CD168) have been implicated in the response to acute lung injury. We hypothesized that, compared to wild type (WT) mice, RHAMM knockout (KO) mice would be protected from, whereas mice with macrophage-specific transgenic overexpression of RHAMM (TG) would have worse inflammation, respiratory distress and fibrosis after intratracheal (IT) bleomycin. Compared to WT mice, 10 days after IT bleomycin, RHAMM KO mice had less weight loss, less increase in respiratory rate, and fewer CD45+ cells in the lung. At day 28, compared to injured WT animals, injured RHAMM KO mice had lower M1 macrophage content, as well as decreased fibrosis as determined by trichrome staining, Ashcroft scores and lung HPO content. Four lines of transgenic mice with selective overexpression of RHAMM in macrophages were generated using the Scavenger Receptor A promoter driving a myc-tagged full length RHAMM cDNA. Baseline expression of RHAMM and CD44 was the same in WT and TG mice. By flow cytometry, TG bone marrow-derived macrophages (BMDM) had increased cell surface RHAMM and myc, but equal CD44 expression. TG BMDM also had 2-fold increases in both chemotaxis to HA and proliferation in fetal bovine serum. In TG mice, increased inflammation after thioglycollate-induced peritonitis was restricted to macrophages and not neutrophils. For lung injury studies, non-transgenic mice given bleomycin had respiratory distress with increased respiratory rates from day 7 to 21. However, TG mice had higher respiratory rates from 4 days after bleomycin and continued to increase respiratory rates up to day 21. At 21 days after IT bleomycin, TG mice had increased lung macrophage accumulation. Lavage HA concentrations were 6-fold higher in injured WT mice, but 30-fold higher in injured TG mice. At 21 days after IT bleomycin, WT mice had developed fibrosis, but TG mice showed exaggerated fibrosis with increased Ashcroft scores and HPO content. We conclude that RHAMM is a critical component of the inflammatory response, respiratory distress and fibrosis after acute lung injury. We speculate that RHAMM is a potential therapeutic target to limit the consequences of acute lung injury.

Immunohistochemical analysis of RHAMM expression in normal and neoplastic human tissues: a cell cycle protein with distinctive expression in mitotic cells and testicular germ cells

Expression of Receptor for Hyaluronic Acid Mediated Motility (RHAMM) increases cellular motility and RHAMM overexpression promotes invasive phenotype and metastasis of cancer cells. RHAMM has been suggested as a biomarker for poor prognosis in several tumor types, including lung, breast, colorectal, gastric, pancreatic ductal, and ovarian cancers. RNA studies showed restricted RHAMM expression in normal tissues, but its protein expression data in tissues were limited. In light of its potential as a prognostic marker and a therapeutic target, we performed immunohistochemical analysis to systematically characterize RHAMM expression in normal and neoplastic human tissues. Among 29 normal adult tissues, RHAMM protein showed restricted expression and was observed in the thymus, lymph node/tonsil, small intestine, colon, skin, bone marrow, placenta, and testis. The cellular distribution patterns of RHAMM in these normal tissues were consistent with RHAMM being a G2/M cell cycle protein, and this was further supported in comparison to the expression of cyclin B2, another G2/M protein. However, unlike the subcellular localization of cyclin B2, RHAMM decorated mitotic spindles in both anaphase and metaphase. RHAMM expression in tumor tissues is variable; and higher RHAMM protein expression is associated with histologically higher-grade tumors in general. Distinct from its expression in somatic tissues, RHAMM showed diffuse, strong, stage-specific expression in the spermatocyte stage of germ cells in adult testis. The neoplastic counterpart, spermatocytic tumor, also showed strong RHAMM expression. This unique expression in testis suggests that RHAMM may function during normal testicular germ cell maturation.

The nonmotor adaptor HMMR dampens Eg5-mediated forces to preserve the kinetics and integrity of chromosome segregation

The nonmotor adaptor protein HMMR maintains the kinetics and integrity of chromosome segregation by promoting TPX2-Eg5 complexes that dampen Eg5-mediated forces and support K-fiber stability, kinetochore–microtubule attachments, and inter-kinetochore tension. HMMR is needed to prevent the generation of aneuploid progeny cells.

Mitotic spindle assembly and organization require forces generated by motor proteins. The activity of these motors is regulated by nonmotor adaptor proteins. However, there are limited studies reporting the functional importance of adaptors on the balance of motor forces and the promotion of faithful and timely cell division. Here we show that genomic deletion or small interfering RNA silencing of the nonmotor adaptor Hmmr/HMMR disturbs spindle microtubule organization and bipolar chromosome–kinetochore attachments with a consequent elevated occurrence of aneuploidy. Rescue experiments show a conserved motif in HMMR is required to generate interkinetochore tension and promote anaphase entry. This motif bears high homology with the kinesin Kif15 and is known to interact with TPX2, a spindle assembly factor. We find that HMMR is required to dampen kinesin Eg5-mediated forces through localizing TPX2 and promoting the formation of inhibitory TPX2-Eg5 complexes. In HMMR-silenced cells, K-fiber stability is reduced while the frequency of unattached chromosomes and the time needed for chromosome segregation are both increased. These defects can be alleviated in HMMR-silenced cells with chemical inhibition of Eg5 but not through the silencing of Kif15. Together, our findings indicate that HMMR balances Eg5-­mediated forces to preserve the kinetics and integrity of chromosome segregation.