Loss of WNK2 expression by promoter gene methylation occurs in adult gliomas and triggers Rac1-mediated tumour cell invasiveness

Preservation of circadian rhythm in hepatocellular cancer

Circadian rhythms are controlled at the cellular level by a molecular clock consisting of several genes/proteins engaged in a transcription-translation-degradation feedback loop. These core clock proteins regulate thousands of tissue-specific genes. Regarding circadian control in neoplastic tissues, reports to date have demonstrated anomalous circadian function in tumor models and cultured tumor cells. We have extended these studies by analyzing circadian rhythmicity genome-wide in a mouse model of liver cancer, in which mice treated with diethylnitrosamine at 15 days develop liver tumors by 6 months. We injected tumor-bearing and control tumor-free mice with cisplatin every 2 h over a 24-h cycle; 2 h after each injection mice were sacrificed and gene expression was measured by XR-Seq (excision repair sequencing) assay. Rhythmic expression of several core clock genes was observed in both healthy liver and tumor, with clock genes in tumor exhibiting typically robust amplitudes and a modest phase advance. Interestingly, although normal hepatic cells and hepatoma cancer cells expressed a comparable number of genes with circadian rhythmicity (clock-controlled genes), there was only about 10% overlap between the rhythmic genes in normal and cancerous cells. "Rhythmic in tumor only" genes exhibited peak expression times mainly in daytime hours, in contrast to the more common pre-dawn and pre-dusk expression times seen in healthy livers. Differential expression of genes in tumors and healthy livers across time may present an opportunity for more efficient anticancer drug treatment as a function of treatment time.

ASCL1-ERK1/2 Axis: ASCL1 restrains ERK1/2 via the dual specificity phosphatase DUSP6 to promote survival of a subset of neuroendocrine lung cancers

The transcription factor achaete-scute complex homolog 1 (ASCL1) is a lineage oncogene that is central for the growth and survival of small cell lung cancers (SCLC) and neuroendocrine non-small cell lung cancers (NSCLC-NE) that express it. Targeting ASCL1, or its downstream pathways, remains a challenge. However, a potential clue to overcoming this challenage has been information that SCLC and NSCLC-NE that express ASCL1 exhibit extremely low ERK1/2 activity, and efforts to increase ERK1/2 activity lead to inhibition of SCLC growth and surival. Of course, this is in dramatic contrast to the majority of NSCLCs where high activity of the ERK pathway plays a major role in cancer pathogenesis. A major knowledge gap is defining the mechanism(s) underlying the low ERK1/2 activity in SCLC, determining if ERK1/2 activity and ASCL1 function are inter-related, and if manipulating ERK1/2 activity provides a new therapeutic strategy for SCLC. We first found that expression of ERK signaling and ASCL1 have an inverse relationship in NE lung cancers: knocking down ASCL1 in SCLCs and NE-NSCLCs increased active ERK1/2, while inhibition of residual SCLC/NSCLC-NE ERK1/2 activity with a MEK inhibitor increased ASCL1 expression. To determine the effects of ERK activity on expression of other genes, we obtained RNA-seq from ASCL1-expressing lung tumor cells treated with an ERK pathway MEK inhibitor and identified down-regulated genes (such as SPRY4, ETV5, DUSP6, SPRED1) that potentially could influence SCLC/NSCLC-NE tumor cell survival. This led us to discover that genes regulated by MEK inhibition suppress ERK activation and CHIP-seq demonstrated these are bound by ASCL1. In addition, SPRY4, DUSP6, SPRED1 are known suppressors of the ERK1/2 pathway, while ETV5 regulates DUSP6. Survival of NE lung tumors was inhibited by activation of ERK1/2 and a subset of ASCL1-high NE lung tumors expressed DUSP6. Because the dual specificity phosphatase 6 (DUSP6) is an ERK1/2-selective phosphatase that inactivates these kinases and has a pharmacologic inhibitor, we focused mechanistic studies on DUSP6. These studies showed: Inhibition of DUSP6 increased active ERK1/2, which accumulated in the nucleus; pharmacologic and genetic inhibition of DUSP6 affected proliferation and survival of ASCL1-high NE lung cancers; and that knockout of DUSP6 "cured" some SCLCs while in others resistance rapidly developed indicating a bypass mechanism was activated. Thus, our findings fill this knowledge gap and indicate that combined expression of ASCL1, DUSP6 and low phospho-ERK1/2 identify some neuroendocrine lung cancers for which DUSP6 may be a therapeutic target.

Germline mutations in WNK2 could be associated with serrated polyposis syndrome

BACKGROUND

Patients with serrated polyposis syndrome (SPS) have multiple and/or large serrated colonic polyps and higher risk for colorectal cancer. SPS inherited genetic basis is mostly unknown. We aimed to identify new germline predisposition factors for SPS by functionally evaluating a candidate gene and replicating it in additional SPS cohorts.

METHODS

After a previous whole-exome sequencing in 39 SPS patients from 16 families (discovery cohort), we sequenced specific genes in an independent validation cohort of 211 unrelated SPS cases. Additional external replication was also available in 297 SPS cases. The WNK2 gene was disrupted in HT-29 cells by gene editing, and WNK2 variants were transfected using a lentiviral delivery system. Cells were analysed by immunoblots, real-time PCR and functional assays monitoring the mitogen-activated protein kinase (MAPK) pathway, cell cycle progression, survival and adhesion.

RESULTS

We identified 2 rare germline variants in the WNK2 gene in the discovery cohort, 3 additional variants in the validation cohort and 10 other variants in the external cohorts. Variants c.2105C>T (p.Pro702Leu), c.4820C>T (p.Ala1607Val) and c.6157G>A (p.Val2053Ile) were functionally characterised, displaying higher levels of phospho-PAK1/2, phospho-ERK1/2, CCND1, clonogenic capacity and MMP2.

CONCLUSION

After whole-exome sequencing in SPS cases with familial aggregation and replication of results in additional cohorts, we identified rare germline variants in the WNK2 gene. Functional studies suggested germline WNK2 variants affect protein function in the context of the MAPK pathway, a molecular hallmark in this disease.

Mitoepigenetics and gliomas: epigenetic alterations to mitochondrial DNA and nuclear DNA alter mtDNA expression and contribute to glioma pathogenicity

Epigenetic mechanisms allow cells to fine-tune gene expression in response to environmental stimuli. For decades, it has been known that mitochondria have genetic material. Still, only recently have studies shown that epigenetic factors regulate mitochondrial DNA (mtDNA) gene expression. Mitochondria regulate cellular proliferation, apoptosis, and energy metabolism, all critical areas of dysfunction in gliomas. Methylation of mtDNA, alterations in mtDNA packaging via mitochondrial transcription factor A (TFAM), and regulation of mtDNA transcription via the micro-RNAs (mir 23-b) and long noncoding RNAs [RNA mitochondrial RNA processing (RMRP)] have all been identified as contributing to glioma pathogenicity. Developing new interventions interfering with these pathways may improve glioma therapy.

An update regarding the role of WNK kinases in cancer

Mammalian WNK kinases (WNKs) are serine/threonine kinases that contain four members, WNK1-4. They function to maintain ion homeostasis and regulate blood pressure in mammals. Recent studies have revealed that the dysregulation of WNKs contributes to tumor growth, metastasis, and angiogenesis through complex mechanisms, especially through phosphorylating kinase substrates SPS1-related proline/alanine-rich kinase (SPAK) and oxidative stress-responsive kinase 1 (OSR1). Here, we review and discuss the relationships between WNKs and several key factors/biological processes in cancer, including ion channels, cation chloride cotransporters, sodium bicarbonate cotransporters, signaling pathways, angiogenesis, autophagy, and non-coding RNAs. In addition, the potential drugs for targeting WNK-SPAK/OSR1 signaling have also been discussed. This review summarizes and discusses knowledge of the roles of WNKs in cancer, which provides a comprehensive reference for future studies.

Circ_0001666 affects miR-620/WNK2 axis to inhibit breast cancer progression

BACKGROUND

Circular RNAs (circRNAs) play important roles in the progression of various cancers, including breast cancer (BC). However, the role of circ_0001666 in BC remains unclear.

OBJECTIVE

To explore the role of circ_0001666 in the progression of BC and reveal its potential molecular mechanism.

METHODS

Real-time polymerase chain reaction was conducted to determine the expression of circ_0001666, miR-620 and with-no-lysine kinase 2 (WNK2). Cell counting kit 8 assay, flow cytometry and transwell assay were used to measure cell proliferation, apoptosis, migration and invasion. Western blot was utilized to examine the level of protein. Dual-luciferase reporter assay and RNA immunoprecipitation assay were used to verify the interaction between miR-620 and circ_0001666 or WNK2. Mice xenotransplantation models were built to explore the effect of circ_0001666 on BC tumor growth in vivo.

RESULTS

Circ_0001666 was downregulated in BC tumor tissues and cells. Overexpressed circ_0001666 inhibited the proliferation, migration, invasion, while promoted apoptosis and tumor growth of BC in vitro or in vivo. Furthermore, circ_0001666 could serve as a sponge of miR-620. MiR-620 inhibitor hindered BC cell progression, which was similar to the effect of circ_0001666 overexpression. WNK2 was a target of miR-620, and circ_0001666 could sponge miR-620 to positive regulate WNK2. The knockdown of WNK2 reversed the effect of circ_0001666 overexpression on BC progression.

CONCLUSION

Circ_0001666 hindered the progression of BC via miR-620/WNK2 axis.

Adult-type granulosa cell tumor of the ovary: a FOXL2-centric disease

Adult-type granulosa cell tumors (aGCTs) account for 90% of malignant ovarian sex cord-stromal tumors and 2-5% of all ovarian cancers. These tumors are usually diagnosed at an early stage and are treated with surgery. However, one-third of patients relapse between 4 and 8 years after initial diagnosis, and there are currently no effective treatments other than surgery for these relapsed patients. As the majority of aGCTs (>95%) harbor a somatic mutation in FOXL2 (c.C402G; p.C134W), the aim of this study was to identify genetic mutations besides FOXL2 C402G in aGCTs that could explain the clinical diversity of this disease. Whole-genome sequencing of 10 aGCTs and their matched normal blood was performed to identify somatic mutations. From this analysis, a custom amplicon-based panel was designed to sequence 39 genes of interest in a validation cohort of 83 aGCTs collected internationally. KMT2D inactivating mutations were present in 10 of 93 aGCTs (10.8%), and the frequency of these mutations was similar between primary and recurrent aGCTs. Inactivating mutations, including a splice site mutation in candidate tumor suppressor WNK2 and nonsense mutations in PIK3R1 and NLRC5, were identified at a low frequency in our cohort. Missense mutations were identified in cell cycle-related genes TP53, CDKN2D, and CDK1. From these data, we conclude that aGCTs are comparatively a homogeneous group of tumors that arise from a limited set of genetic events and are characterized by the FOXL2 C402G mutation. Secondary mutations occur in a subset of patients but do not explain the diverse clinical behavior of this disease. As the FOXL2 C402G mutation remains the main driver of this disease, progress in the development of therapeutics for aGCT would likely come from understanding the functional consequences of the FOXL2 C402G mutation.

Epigenetics of glioblastoma multiforme: From molecular mechanisms to therapeutic approaches

Glioblastoma multiforme (GBM) is the most common form of brain cancer and one of the most aggressive cancers found in humans. Most of the signs and symptoms of GBM can be mild and slowly aggravated, although other symptoms might demonstrate it as an acute ailment. However, the precise mechanisms of the development of GBM remain unknown. Due to the improvement of molecular pathology, current researches have reported that glioma progression is strongly connected with different types of epigenetic phenomena, such as histone modifications, DNA methylation, chromatin remodeling, and aberrant microRNA. Furthermore, the genes and the proteins that control these alterations have become novel targets for treating glioma because of the reversibility of epigenetic modifications. In some cases, gene mutations including P16, TP53, and EGFR, have been observed in GBM. In contrast, monosomies, including removals of chromosome 10, particularly q23 and q25-26, are considered the standard markers for determining the development and aggressiveness of GBM. Recently, amid the epigenetic therapies, histone deacetylase inhibitors (HDACIs) and DNA methyltransferase inhibitors have been used for treating tumors, either single or combined. Specifically, HDACIs are served as a good choice and deliver a novel pathway to treat GBM. In this review, we focus on the epigenetics of GBM and the consequence of its mutations. We also highlight various treatment approaches, namely gene editing, epigenetic drugs, and microRNAs to combat GBM.

Upregulated CBX8 Promotes Cancer Metastasis via the WNK2/MMP2 Pathway

Metastasis is associated with poor prognosis in cancer and is a multistep process that includes invasion and migration. Several epigenetic factors are involved in this process, including chromobox protein homolog 8 (CBX8). Here, we show that CBX8 is overexpressed in many cancers compared with normal tissues. Functional analyses indicated that CBX8 promoted invasion and migration in glioblastoma, breast cancer, and lung cancer in vitro and in vivo. WNK2 was identified as a target gene of CBX8, which interacted with the WNK2 promoter to suppress WNK2 expression and activity. WNK2 acted as an antioncogene, and decreased WNK2 levels resulted in high activity of matrix metalloprotease (MMP)-2 and RAC1, which play a central role in invasion and migration, respectively. There was a positive relationship between MMP2 and RAC1 activity in CBX8-modulated cell lines. In addition, WNK2 negatively regulated MMP2 and RAC1 activity. Collectively, the results indicated that CBX8 promoted invasion and migration by targeting WNK2, which resulted in increased RAC1 and MMP2 expression and activity. Therefore, CBX8 may be a novel therapeutic target to treat metastatic cancers.

Is DNA Methylation a Ray of Sunshine in Predicting Meningioma Prognosis?

Meningioma is the most common intracranial tumor, and recent studies have drawn attention to the importance of further research on malignant meningioma. According to the World Health Organization (WHO) grading, meningioma is classified into 15 subtypes with three grades of malignancy. However, due to a lack of descriptions of molecular subtypes, genetic mutations, or other features, there were deficiencies in the WHO classification. The DNA methylation-based meningioma classification published in 2017 used DNA copy number analysis, mutation profiling, and RNA sequencing to distinguish six clinically relevant methylation classes, which contributed to a better prediction of tumor recurrence and prognosis. Further studies indicated that gene variation and gene mutations, such as those in neurofibromin 2 (NF2) and BRCA1, were related to the high WHO grade, malignant invasion, and recurrence. Among the mutant genes described above, some have been associated with differential DNA methylation. Herein, we searched for articles published in PubMed and Web of Science from January 2000 to May 2020 by entering the keywords “meningioma,” “methylation,” and “gene mutation,” and found a number of published studies that analyzed DNA methylation in meningiomas. In this review, we summarize the key findings of recent studies on methylation status and genetic mutations of meningioma and discuss the current deficits of the WHO grading. We also propose that a methylation-based meningioma classification could provide clues in the assessment of individual risk of meningioma recurrence, which is associated with clinical benefits for patients.

Long non-coding RNA LINC00858 inhibits colon cancer cell apoptosis, autophagy, and senescence by activating WNK2 promoter methylation

Accumulating evidence shows the involvement of long non-coding RNAs (lncRNAs) in tumorigenesis of many types of human cancers. However, the role of LINC00858 in colon cancer has not been fully elucidated. Therefore, we investigated the involvement of LINC00858 in the progression of colon cancer and identified its downstream targets. After examining the expression of LINC00858 in colon cancer tissues and cell lines, we then identified the possible interaction between LINC00858 and WNK lysine deficient protein kinase 2 (WNK2) by fluorescence in situ hybridization, RNA immunoprecipitation, chromatin immunoprecipitation, and RNA pull-down assays. Next, the role of the LINC00858/WNK2 axis was explored by evaluating the apoptosis, autophagy, and senescence of colon cancer cells in vitro after ectopic expression and depletion experiments in HCT116 cells. Moreover, a mouse xenograft model of HCT116 cells was established to verify the function of the LINC00858/WNK2 axis in vivo. There was high expression of LINC00858 and low expression of WNK2 in colon cancer tissues and cell lines. Silencing of LINC00858 promoted apoptosis, senescence, and autophagy in colon cancer cells. Additionally, the enrichment of WNK2 was promoted when LINC00858 bound to DNA methyltransferases. Furthermore, in vivo assays demonstrated that silencing of LINC00858 resulted in inhibited tumor growth by upregulating WNK2. In summary, LINC00858 acts as a tumor-promoting lncRNA in colon cancer by downregulating WNK2. Our results may provide novel targets for the treatment for colon cancer.

LINC00858 knockdown inhibits gastric cancer cell growth and induces apoptosis through reducing WNK2 promoter methylation

BACKGROUND

Emerging evidence indicates a regulatory role of long non-coding RNAs (lncRNAs) in the development of gastric cancer (GC), but the mechanisms underlying their function have remained largely unknown. Recent microarray-based expression profiling has led to the identification of a novel differentially expressed lncRNA, LINC00858, in GC. Subsequently, LINC00858 was found to be highly expressed in GC tissues and cells. This study was designed to clarify the functional role of LINC00858 in GC, including its effect on methylation of the WNK2 gene promoter and its downstream MAPK signaling pathway.

METHODS

After exogenous over-expression and knockdown of LINC00858 and the addition of a MAPK pathway inhibitor in GC cells, we explored the effects of LINC00858 and the MAPK signaling pathway on GC cell behavior using various in vitro and in vivo assays.

RESULTS

LINC00858 was found to negatively regulate WNK2 expression by enhancing its promoter methylation and to activate the MAPK signaling pathway. Moreover, we found that knockdown of LINC00858 or inhibition of the MAPK signaling pathway resulted in decreased GC cell growth, migration and invasion, as well as decreased cell cycle progression, along with increased apoptosis and decreased tumorigenicity.

CONCLUSIONS

Together, these findings indicate that silencing of LINC00858 increases WNK2 expression and inhibits the MAPK signaling pathway, thereby inhibiting GC growth and development. Our data highlight LINC00858 as a potential target in GC therapy.

The T-box transcription factor brachyury behaves as a tumor suppressor in gliomas

The oncogene brachyury (TBXT) is a T-box transcription factor that is overexpressed in multiple solid tumors and is associated with tumor aggressiveness and poor patient prognosis. Gliomas comprise the most common and aggressive group of brain tumors, and at the present time the functional and clinical impact of brachyury expression has not been investigated previously in these neoplasms. Brachyury expression (mRNA and protein) was assessed in normal brain (n = 67), glioma tissues (n = 716) and cell lines (n = 42), and further in silico studies were undertaken using genomic databases totaling 3115 samples. Our glioma samples were analyzed for copy number (n = 372), promoter methylation status (n = 170), and mutation status (n = 1569 tissues and n = 52 cell lines) of the brachyury gene. The prognostic impact of brachyury expression was studied in 1524 glioma patient tumors. The functional impact of brachyury on glioma proliferation, viability, and cell death was evaluated both in vitro and in vivo. Brachyury was expressed in the normal brain, and significantly downregulated in glioma tissues. Loss of brachyury was associated with tumor aggressiveness and poor survival in glioma patients. Downregulation of brachyury was not associated with gene deletion, promoter methylation, or inactivating point mutations. Brachyury re-expression in glioma cells was found to decrease glioma tumorigenesis by induction of autophagy. These data strongly suggest that brachyury behaves as a tumor suppressor gene in gliomas by modulating autophagy. It is important to note that brachyury constitutes an independent positive biomarker of patient prognosis. Our findings indicate that the role of brachyury in tumorigenesis may be tissue-dependent and demands additional investigation to guide rational interventions. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

WNK2 Inhibits Autophagic Flux in Human Glioblastoma Cell Line

Autophagy is a cell-survival pathway with dual role in tumorigenesis, promoting either tumor survival or tumor death. WNK2 gene, a member of the WNK (with no lysine (K)) subfamily, acts as a tumor suppressor gene in gliomas, regulating cell migration and invasion; however, its role in autophagy process is poorly explored. The WNK2-methylated human glioblastoma cell line A172 WT (wild type) was compared to transfected clones A172 EV (empty vector), and A172 WNK2 (WNK2 overexpression) for the evaluation of autophagy using an inhibitor (bafilomycin A1-baf A1) and an inducer (everolimus) of autophagic flux. Western blot and immunofluorescence approaches were used to monitor autophagic markers, LC3A/B and SQSTM1/p62. A172 WNK2 cells presented a significant decrease in LC3B and p62 protein levels, and in LC3A/B ratio when compared with control cells, after treatment with baf A1 + everolimus, suggesting that WNK2 overexpression inhibits the autophagic flux in gliomas. The mTOR pathway was also evaluated under the same conditions, and the observed results suggest that the inhibition of autophagy mediated by WNK2 occurs through a mTOR-independent pathway. In conclusion, the evaluation of the autophagic process demonstrated that WNK2 inhibits the autophagic flux in glioblastoma cell line.

Long non-coding RNA LINC00858 exerts a tumor-promoting role in colon cancer via HNF4α and WNK2 regulation

BACKGROUND

Long non-coding RNAs (lncRNAs) are known to be frequently dysregulated in many types of human cancer. As yet, however, their roles in colon carcinogenesis have not been fully elucidated. In the current study, we assessed whether lncRNA LINC00858 may be involved in the progression of colon cancer and, in addition, investigated its downstream targets.

METHODS

LINC00858 expression in patient-derived colon cancer tissues and in colon cancer cell lines was determined using RT-qPCR. Also, relationships between LINC00858 expression and various clinicopathological characteristics were analyzed. The subcellular localization of LINC00858 was determined using fluorescence in situ hybridization. Interactions between LINC00858 and its downstream targets were first predicted by bioinformatic analysis and, subsequently, confirmed by RNA pull-down, RNA immunoprecipitation, chromatin immunoprecipitation and dual luciferase reporter assays. After in vitro upregulation of LINC00858 and/or silencing of WNK2 and hepatocyte nuclear factor 4α (HNF4α), the biological behavior of colon cancer cells was assessed using 5-ethynyl-2'-deoxyuridine (EdU) incorporation, Transwell invasion and tube formation assays. In vivo cancer growth was evaluated in nude mice.

RESULTS

We found that LINC00858 was highly expressed in primary colon cancer tissues and colon cancer cell lines, and was mainly located in the nucleus. High LINC00858 expression was found to correlate with a poor differentiation, advanced TNM stages and lymph node metastasis. Exogenous overexpression of LINC00858 promoted cell proliferation, invasion and migration of colon cancer cells, and facilitated angiogenesis and tumor growth. In addition, we found that LINC00858 can bind to and upregulate the nuclear transcription factor HNF4α, leading to WNK2 expression downregulation. This, in turn, resulted in the promotion of colon cancer cell growth.

CONCLUSIONS

From our data we conclude that LINC00858 acts as a tumor-promoting lncRNA in colon cancer by upregulating HNF4α and downregulating WNK2. Our results may provide novel targets for the treatment for colon cancer.

Loss of SPINT2 expression frequently occurs in glioma, leading to increased growth and invasion via MMP2

PURPOSE

High-grade gliomas (HGG) remain one of the most aggressive tumors, which is primarily due to its diffuse infiltrative nature. Serine proteases and metalloproteases are known to play key roles in cellular migration and invasion mechanisms. SPINT2, also known as HAI-2, is an important serine protease inhibitor that can affect MET signaling. SPINT2 has been found to be frequently downregulated in various tumors, whereby hypermethylation of its promoter appears to serve as a common mechanism. Here, we assessed the clinical relevance of SPINT2 expression and promoter hypermethylation in pediatric and adult HGG and explored its functional role.

METHODS

A series of 371 adult and 77 pediatric primary HGG samples was assessed for SPINT2 protein expression (immunohistochemistry) and promoter methylation (methylation-specific PCR) patterns. After SPINT2 knockdown and knock-in in adult and pediatric HGG cell lines, a variety of in vitro assays was carried out to determine the role of SPINT2 in glioma cell viability and invasion, as well as their mechanistic associations with metalloprotease activities.

RESULTS

We found that SPINT2 protein expression was frequently absent in adult (85.3%) and pediatric (100%) HGG samples. The SPINT2 gene promoter was found to be hypermethylated in approximately half of both adult and pediatric gliomas. Through functional assays we revealed a suppressor activity of SPINT2 in glioma cell proliferation and viability, as well as in their migration and invasion. These functions appear to be mediated in part by MMP2 expression and activity.

CONCLUSIONS

We conclude that dysregulation of SPINT2 is a common event in both pediatric and adult HGG, in which SPINT2 may act as a tumor suppressor.

Global DNA methylation synergistically regulates the nuclear and mitochondrial genomes in glioblastoma cells

Replication of mitochondrial DNA is strictly regulated during differentiation and development allowing each cell type to acquire its required mtDNA copy number to meet its specific needs for energy. Undifferentiated cells establish the mtDNA set point, which provides low numbers of mtDNA copy but sufficient template for replication once cells commit to specific lineages. However, cancer cells, such as those from the human glioblastoma multiforme cell line, HSR-GBM1, cannot complete differentiation as they fail to enforce the mtDNA set point and are trapped in a ‘pseudo-differentiated’ state. Global DNA methylation is likely to be a major contributing factor, as DNA demethylation treatments promote differentiation of HSR-GBM1 cells. To determine the relationship between DNA methylation and mtDNA copy number in cancer cells, we applied whole genome MeDIP-Seq and RNA-Seq to HSR-GBM1 cells and following their treatment with the DNA demethylation agents 5-azacytidine and vitamin C. We identified key methylated regions modulated by the DNA demethylation agents that also induced synchronous changes to mtDNA copy number and nuclear gene expression. Our findings highlight the control exerted by DNA methylation on the expression of key genes, the regulation of mtDNA copy number and establishment of the mtDNA set point, which collectively contribute to tumorigenesis.

Contribution of the WNK1 kinase to corneal wound healing using the tissue-engineered human cornea as an in vitro model

Damage to the corneal epithelium triggers important changes in the extracellular matrix (ECM) to which basal human corneal epithelial cells (hCECs) attach. These changes are perceived by integrin receptors that activate different intracellular signalling pathways, ultimately leading to re-epithelialization of the injured epithelium. In this study, we investigated the impact of pharmacological inhibition of specific signal transduction mediators on corneal wound healing using both monolayers of hCECs and the human tissue-engineered cornea (hTEC) as an in vitro 3D model. RNA and proteins were isolated from the wounded and unwounded hTECs to conduct gene profiling analyses and protein kinase arrays. The impact of WNK1 inhibition was evaluated on the wounded hTECs as well as on hCECs monolayers using a scratch wound assay. Gene profiling and protein kinase arrays revealed that expression and activity of several mediators from the integrin-dependent signaling pathways were altered in response to the ECM changes occurring during corneal wound healing. Phosphorylation of the WNK1 kinase turned out to be the most striking activation event going on during this process. The inhibition of WNK1 by WNK463 reduced the rate of corneal wound closure in both the hTEC and hCECs grown in monolayer compared with their respective negative controls. WNK463 also reduced phosphorylation of the WNK1 downstream targets SPAK/OSR1 in wounded hTECs. These in vitro results allowed for a better understanding of the cellular and molecular mechanisms involved in corneal wound healing and identified WNK1 as a kinase important to ensure proper wound healing of the cornea.

Potential Epigenetic-Based Therapeutic Targets for Glioma

Glioma is characterized by a high recurrence rate, short survival times, high rates of mortality and treatment difficulties. Surgery, chemotherapy and radiation (RT) are the standard treatments, but outcomes rarely improve even after treatment. With the advancement of molecular pathology, recent studies have found that the development of glioma is closely related to various epigenetic phenomena, including DNA methylation, abnormal microRNA (miRNA), chromatin remodeling and histone modifications. Owing to the reversibility of epigenetic modifications, the proteins and genes that regulate these changes have become new targets in the treatment of glioma. In this review, we present a summary of the potential therapeutic targets of glioma and related effective treating drugs from the four aspects mentioned above. We further illustrate how epigenetic mechanisms dynamically regulate the pathogenesis and discuss the challenges of glioma treatment. Currently, among the epigenetic treatments, DNA methyltransferase (DNMT) inhibitors and histone deacetylase inhibitors (HDACIs) can be used for the treatment of tumors, either individually or in combination. In the treatment of glioma, only HDACIs remain a good option and they provide new directions for the treatment. Due to the complicated pathogenesis of glioma, epigenetic applications to glioma clinical treatment are still limited.

Hexane partition from Annona crassiflora Mart. promotes cytotoxity and apoptosis on human cervical cancer cell lines

Cervical cancer is the third most commonly diagnosed tumor type and the fourth cause of cancer-related death in females. Therapeutic options for cervical cancer patients remain very limited. Annona crassiflora Mart. is used in traditional medicine as antimicrobial and antineoplastic agent. However, little is known about its antitumoral properties. In this study the antineoplastic effect of crude extract and derived partitions from A. crassiflora Mart in cervical cancer cell lines was evaluated. The crude extract significantly alters cell viability of cervical cancer cell lines as well as proliferation and migration, and induces cell death in SiHa cells. Yet, the combination of the crude extract with cisplatin leads to antagonistic effect. Importantly, the hexane partition derived from the crude extract presented cytotoxic effect both in vitro and in vivo, and initiates cell responses, such as DNA damage (H2AX activity), apoptosis via intrinsic pathway (cleavage of caspase-9, caspase-3, poly (ADP-ribose) polymerase (PARP) and mitochondrial membrane depolarization) and decreased p21 expression by ubiquitin proteasome pathway. Concluding, this work shows that hexane partition triggers several biological responses such as DNA damage and apoptosis, by intrinsic pathways, and was also able to promote a direct decrease in tumor perimeter in vivo providing a basis for further investigation on its antineoplastic activity on cervical cancer.

Role of WNK Kinases in the Modulation of Cell Volume

Ion Transport across the cell membrane is required to maintain cell volume homeostasis. In response to changes in extracellular osmolarity, most cells activate specific metabolic or membrane-transport pathways to respond to cell swelling or shrinkage and return their volume to its normal resting state. This process involves the rapid adjustment of the activities of channels and transporters that mediate flux of K⁺, Na⁺, Cl^-, and small organic osmolytes. Cation chloride cotransporters (CCCs) NKCCs and KCCs are a family of membrane proteins modulated by changes in cell volume and/or in the intracellular chloride concentration ([Cl^-]_i). Cell swelling triggers regulatory volume decrease (RVD), promoting solute and water efflux to restore normal cell volume. Swelling-activated KCCs mediate RVD in most cell types. In contrast, cell shrinkage triggers regulatory volume increase (RVI), which involves the activation of the NKCC1 cotransporter of the CCC family. Regulation of the CCCs during RVI and RVD by protein phosphorylation is a well-characterized mechanism, where WNK kinases and their downstream kinase substrates, SPAK and OSR1 constitute the essential phospho-regulators. WNKs-SPAK/OSR1-CCCs complex is required to regulate cell shrinkage-induced RVI or cell swelling-induced RVD via activating or inhibitory phosphorylation of NKCCs or KCCs, respectively. WNK1 and WNK4 kinases have been established as [Cl^-]_i sensors/regulators, while a role for WNK3 kinase as a cell volume-sensing kinase has emerged and is proposed in this chapter.

Functional diversity and cooperativity between subclonal populations of pediatric glioblastoma and diffuse intrinsic pontine glioma cells

The failure to develop effective therapies for pediatric glioblastoma (pGBM) and diffuse intrinsic pontine glioma (DIPG) is in part due to their intrinsic heterogeneity. We aimed to quantitatively assess the extent to which this was present in these tumors through subclonal genomic analyses and to determine whether distinct tumor subpopulations may interact to promote tumorigenesis by generating subclonal patient-derived models in vitro and in vivo. Analysis of 142 sequenced tumors revealed multiple tumor subclones, spatially and temporally coexisting in a stable manner as observed by multiple sampling strategies. We isolated genotypically and phenotypically distinct subpopulations that we propose cooperate to enhance tumorigenicity and resistance to therapy. Inactivating mutations in the H4K20 histone methyltransferase KMT5B (SUV420H1), present in <1% of cells, abrogate DNA repair and confer increased invasion and migration on neighboring cells, in vitro and in vivo, through chemokine signaling and modulation of integrins. These data indicate that even rare tumor subpopulations may exert profound effects on tumorigenesis as a whole and may represent a new avenue for therapeutic development. Unraveling the mechanisms of subclonal diversity and communication in pGBM and DIPG will be an important step toward overcoming barriers to effective treatments.

In vitro screening of cytotoxic activity of euphol from Euphorbia tirucalli on a large panel of human cancer-derived cell lines

A large number of classic antineoplastic agents are derived from plants. Euphorbia tirucalli L. (Euphorbiaceae) is a subtropical and tropical plant, used in Brazilian folk medicine against many diseases, including cancer, yet little is known about its true anticancer properties. The present study evaluated the antitumor effect of the tetracyclic triterpene alcohol, euphol, the main constituent of E. tirucalli in a panel of 73 human cancer lines from 15 tumor types. The biological effect of euphol in pancreatic cells was also assessed. The combination index was further used to explore euphol interactions with standard drugs. Euphol showed a cytotoxicity effect against several cancer cell lines (IC₅₀ range, 1.41–38.89 µM), particularly in esophageal squamous cell (11.08 µM) and pancreatic carcinoma cells (6.84 µM), followed by prostate, melanoma, and colon cancer. Cytotoxicity effects were seen in all cancer cell lines, with more than half deemed highly sensitive. Euphol inhibited proliferation, motility and colony formation in pancreatic cancer cells. Importantly, euphol exhibited synergistic interactions with gemcitabine and paclitaxel in pancreatic and esophageal cell lines, respectively. To the best of our knowledge, this study constitutes the largest in vitro screening of euphol efficacy on cancer cell lines and revealed its in vitro anti-cancer properties, particularly in pancreatic and esophageal cell lines, suggesting that euphol, either as a single agent or in combination with conventional chemotherapy, is a potential anti-cancer drug.

Bauhinia variegata candida Fraction Induces Tumor Cell Death by Activation of Caspase-3, RIP, and TNF-R1 and Inhibits Cell Migration and Invasion In Vitro

Metastasis remains the most common cause of death in cancer patients. Inhibition of metalloproteinases (MMPs) is an interesting approach to cancer therapy because of their role in the degradation of extracellular matrix (ECM), cell-cell, and cell-ECM interactions, modulating key events in cell migration and invasion. Herein, we show the cytotoxic and antimetastatic effects of the third fraction (FR3) from Bauhinia variegata candida (Bvc) stem on human cervical tumor cells (HeLa) and human peripheral blood mononuclear cells (PBMCs). FR3 inhibited MMP-2 and MMP-9 activity, indicated by zymogram. This fraction was cytotoxic to HeLa cells and noncytotoxic to PBMCs and decreased HeLa cell migration and invasion. FR3 is believed to stimulate extrinsic apoptosis together with necroptosis, assessed by western blotting. FR3 inhibited MMP-2 activity in the HeLa supernatant, differently from the control. The atomic mass spectrometry (ESI-MS) characterization suggested the presence of glucopyranosides, D-pinitol, fatty acids, and phenolic acid. These findings provide insight suggesting that FR3 contains components with potential tumor-selective cytotoxic action in addition to the action on the migration of tumor cells, which may be due to inhibition of MMPs.

Hypoxia-mediated upregulation of MCT1 expression supports the glycolytic phenotype of glioblastomas

Background

Glioblastomas (GBM) present a high cellular heterogeneity with conspicuous necrotic regions associated with hypoxia, which is related to tumor aggressiveness. GBM tumors exhibit high glycolytic metabolism with increased lactate production that is extruded to the tumor microenvironment through monocarboxylate transporters (MCTs). While hypoxia-mediated regulation of MCT4 has been characterized, the role of MCT1 is still controversial. Thus, we aimed to understand the role of hypoxia in the regulation of MCT expression and function in GBM, MCT1 in particular.

Methods

Expression of hypoxia- and glycolytic-related markers, as well as MCT1 and MCT4 isoforms was assessed in in vitro and in vivo orthotopic glioma models, and also in human GBM tissues by immunofluorescence/immunohistochemistry and Western blot. Following MCT1 inhibition, either pharmacologically with CHC (α-cyano-4-hydroxynnamic acid) or genetically with siRNAs, we assessed GBM cell viability, proliferation, metabolism, migration and invasion, under normoxia and hypoxia conditions.

Results

Hypoxia induced an increase in MCT1 plasma membrane expression in glioma cells, both in in vitro and in vivo models. Additionally, treatment with CHC and downregulation of MCT1 in glioma cells decreased lactate production, cell proliferation and invasion under hypoxia. Moreover, in the in vivo orthotopic model and in human GBM tissues, there was extensive co-expression of MCT1, but not MCT4, with the GBM hypoxia marker CAIX.

Conclusion

Hypoxia-induced MCT1 supports GBM glycolytic phenotype, being responsible for lactate efflux and an important mediator of cell survival and aggressiveness. Therefore, MCT1 constitutes a promising therapeutic target in GBM.

Multistep regulation of autophagy by WNK1

The with-no-lysine (K) (WNK) kinases are an atypical family of protein kinases that regulate ion transport across cell membranes. Mutations that result in their overexpression cause hypertension-related disorders in humans. Of the four mammalian WNKs, only WNK1 is expressed throughout the body. We report that WNK1 inhibits autophagy, an intracellular degradation pathway implicated in several human diseases. Using small-interfering RNA-mediated WNK1 knockdown, we show autophagosome formation and autophagic flux are accelerated. In cells with reduced WNK1, basal and starvation-induced autophagy is increased. We also show that depletion of WNK1 stimulates focal class III phosphatidylinositol 3-kinase complex (PI3KC3) activity, which is required to induce autophagy. Depletion of WNK1 increases the expression of the PI3KC3 upstream regulator unc-51-like kinase 1 (ULK1), its phosphorylation, and activation of the kinase upstream of ULK1, the AMP-activated protein kinase. In addition, we show that the N-terminal region of WNK1 binds to the UV radiation resistance-associated gene (UVRAG) in vitro and WNK1 partially colocalizes with UVRAG, a component of a PI3KC3 complex. This colocalization decreases upon starvation of cells. Depletion of the SPS/STE20-related proline-alanine-rich kinase, a WNK1-activated enzyme, also induces autophagy in nutrient-replete or -starved conditions, but depletion of the related kinase and WNK1 substrate, oxidative stress responsive 1, does not. These results indicate that WNK1 inhibits autophagy by multiple mechanisms.

Tapirira guianensis Aubl. Extracts Inhibit Proliferation and Migration of Oral Cancer Cells Lines

Cancer of the head and neck is a group of upper aerodigestive tract neoplasms in which aggressive treatments may cause harmful side effects to the patient. In the last decade, investigations on natural compounds have been particularly successful in the field of anticancer drug research. Our aim is to evaluate the antitumor effect of Tapirira guianensis Aubl. extracts on a panel of head and neck squamous cell carcinoma (HNSCC) cell lines. Analysis of secondary metabolites classes in fractions of T. guianensis was performed using Nuclear Magnetic Resonance (NMR). Mutagenicity effect was evaluated by Ames mutagenicity assay. The cytotoxic effect, and migration and invasion inhibition were measured. Additionally, the expression level of apoptosis-related molecules (PARP, Caspases 3, and Fas) and MMP-2 was detected using Western blot. Heterogeneous cytotoxicity response was observed for all fractions, which showed migration inhibition, reduced matrix degradation, and decreased cell invasion ability. Expression levels of MMP-2 decreased in all fractions, and particularly in the hexane fraction. Furthermore, overexpression of FAS and caspase-3, and increase of cleaved PARP indicates possible apoptosis extrinsic pathway activation. Antiproliferative activity of T. guianensis extract in HNSCC cells lines suggests the possibility of developing an anticancer agent or an additive with synergic activities associated with conventional anticancer therapy.

WNK Kinases in Development and Disease

WNK (With-No-Lysine (K)) kinases are serine-threonine kinases characterized by an atypical placement of a catalytic lysine within the kinase domain. Mutations in human WNK1 or WNK4 cause an autosomal dominant syndrome of hypertension and hyperkalemia, reflecting the fact that WNK kinases are critical regulators of renal ion transport processes. Here, the role of WNKs in the regulation of ion transport processes in vertebrate and invertebrate renal function, cellular and organismal osmoregulation, and cell migration and cerebral edema will be reviewed, along with emerging literature demonstrating roles for WNKs in cardiovascular and neural development, Wnt signaling, and cancer. Conserved roles for these kinases across phyla are emphasized.

Transcriptome sequencing reveals a profile that corresponds to genomic variants in Waldenström macroglobulinemia

Whole-genome sequencing has identified highly prevalent somatic mutations including MYD88, CXCR4, and ARID1A in Waldenström macroglobulinemia (WM). The impact of these and other somatic mutations on transcriptional regulation in WM remains to be clarified. We performed next-generation transcriptional profiling in 57 WM patients and compared findings to healthy donor B cells. Compared with healthy donors, WM patient samples showed greatly enhanced expression of the VDJ recombination genes DNTT, RAG1, and RAG2, but not AICDA Genes related to CXCR4 signaling were also upregulated and included CXCR4, CXCL12, and VCAM1 regardless of CXCR4 mutation status, indicating a potential role for CXCR4 signaling in all WM patients. The WM transcriptional profile was equally dissimilar to healthy memory B cells and circulating B cells likely due increased differentiation rather than cellular origin. The profile for CXCR4 mutations corresponded to diminished B-cell differentiation and suppression of tumor suppressors upregulated by MYD88 mutations in a manner associated with the suppression of TLR4 signaling relative to those mutated for MYD88 alone. Promoter methylation studies of top findings failed to explain this suppressive effect but identified aberrant methylation patterns in MYD88 wild-type patients. CXCR4 and MYD88 transcription were negatively correlated, demonstrated allele-specific transcription bias, and, along with CXCL13, were associated with bone marrow disease involvement. Distinct gene expression profiles for patients with wild-type MYD88, mutated ARID1A, familial predisposition to WM, chr6q deletions, chr3q amplifications, and trisomy 4 are also described. The findings provide novel insights into the molecular pathogenesis and opportunities for targeted therapeutic strategies for WM.

(WNK)ing at death: With-no-lysine (Wnk) kinases in neuropathies and neuronal survival

Members of With-no-lysine (WNK) family of serine-threonine kinase are key regulators of chloride ion transport in diverse cell types, controlling the activity and the surface expression of cation-chloride (Na(+)/K(+)-Cl(-)) co-transporters. Mutations in WNK1 and WNK4 are linked to a hereditary form of hypertension, and WNKs have been extensively investigated pertaining to their roles in renal epithelial ion homeostasis. However, some members of the WNK family and their splice isoforms are also expressed in the mammalian brain, and have been implicated in aspects of hereditary neuropathy as well as neuronal and glial survival. WNK2, which is exclusively enriched in neurons, is well known as an anti-proliferative tumor suppressor. WNK3, on the other hand, appears to promote cell survival as its inhibition enhances neuronal apoptosis. However, loss of WNK3 has been recently shown to reduce ischemia-associated brain damage. In this review, I surveyed the potentially context-dependent roles of WNKs in neurological disorders and neuronal survival.

Silencing of the tumor suppressor gene WNK2 is associated with upregulation of MMP2 and JNK in gliomas

Matrix metalloproteinases (MMPs) are proteolytic enzymes that degrade extracellular matrix (ECM), thus assisting invasion. Upregulation of MMPs, frequently reported in gliomas, is associated with aggressive behavior. WNK2 is a tumor suppressor gene expressed in normal brain, and silenced by promoter methylation in gliomas. Patients without WNK2 exhibited poor prognosis, and its downregulation was associated with increased glioma cell invasion. Here we showed that MMP2 expression and activity are increased in glioma cell lines that do not express WNK2. Also, WNK2 inhibited JNK, a process associated with decreasing levels of MMP2. Thus, WNK2 promoter methylation and silencing in gliomas is associated with increased JNK activation and MMP2 expression and activity, thus explaining in part tumor cell invasion potential.

SPINT2 Deregulation in Prostate Carcinoma

SPINT2 is a tumor suppressor gene that inhibits proteases implicated in cancer progression, like HGFA, hepsin and matriptase. Loss of SPINT2 expression in tumors has been associated with gene promoter hypermethylation; however, little is known about the mechanisms of SPINT2 deregulation in prostate cancer (PCa). We aimed to analyze SPINT2 expression levels and understand the possible regulation by SPINT2 promoter hypermethylation in PCa. In a cohort of 57 cases including non-neoplastic and PCa tissues, SPINT2 expression and promoter methylation was analyzed by immunohistochemistry and methylation-specific PCR, respectively. Methylation status of the SPINT2 promoter was also evaluated by bisulfite sequencing and 5-aza-2'-deoxycytidine treatment. Oncomine and TCGA databases were used to perform in silico PCa analysis of SPINT2 mRNA and methylation levels. A reduction in SPINT2 expression levels from non-neoplastic to PCa tissues was observed; however, none of the cases exhibited SPINT2 promoter methylation. Both bisulfite sequencing and 5-aza demonstrated that SPINT2 promoter is not methylated in PCa cells. Bioinformatics approaches did not show downregulation of SPINT2 at the mRNA level and, in corroboration with our results, SPINT2 promoter region is reported to be unmethylated. Our study suggests an involvement of SPINT2 in PCa tumorigenesis, probably in association with a post-translational regulation of SPINT2.

Expression profile of genes modulated by Aloe emodin in human U87 glioblastoma cells

Glioblastoma, the most aggressive and malignant form of glioma, appears to be resistant to various chemotherapeutic agents. Hence, approaches have been intensively investigated to targeti specific molecular pathways involved in glioblastoma development and progression. Aloe emodin is believed to modulate the expression of several genes in cancer cells. We aimed to understand the molecular mechanisms underlying the therapeutic effect of Aloe emodin on gene expression profiles in the human U87 glioblastoma cell line utilizing microarray technology. The gene expression analysis revealed that a total of 8,226 gene alterations out of 28,869 genes were detected after treatment with 58.6 μg/ml for 24 hours. Out of this total, 34 genes demonstrated statistically significant change (p<0.05) ranging from 1.07 to 1.87 fold. The results revealed that 22 genes were up-regulated and 12 genes were down-regulated in response to Aloe emodin treatment. These genes were then grouped into several clusters based on their biological functions, revealing induction of expression of genes involved in apoptosis (programmed cell death) and tissue remodelling in U87 cells (p<0.01). Several genes with significant changes of the expression level e.g. SHARPIN, BCAP31, FIS1, RAC1 and TGM2 from the apoptotic cluster were confirmed by quantitative real-time PCR (qRT-PCR). These results could serve as guidance for further studies in order to discover molecular targets for the cancer therapy based on Aloe emodin treatment.

Downregulation of TES by hypermethylation in glioblastoma reduces cell apoptosis and predicts poor clinical outcome

BACKGROUND

Gliomas are the most common human brain tumors. Glioblastoma, also known as glioblastoma multiform (GBM), is the most aggressive, malignant, and lethal glioma. The investigation of prognostic and diagnostic molecular biomarkers in glioma patients to provide direction on clinical practice is urgent. Recent studies demonstrated that abnormal DNA methylation states play a key role in the pathogenesis of this kind of tumor. In this study, we want to identify a novel biomarker related to glioma initiation and find the role of the glioma-related gene.

METHODS

We performed a methylation-specific microarray on the promoter region to identify methylation gene(s) that may affect outcome of GBM patients. Normal and GBM tissues were collected from Tiantan Hospital. Genomic DNA was extracted from these tissues and analyzed with a DNA promoter methylation microarray. Testis derived transcript (TES) protein expression was analyzed by immunohistochemistry in paraffin-embedded patient tissues. Western blotting was used to detect TES protein expression in the GBM cell line U251 with or without 5-aza-dC treatment. Cell apoptosis was evaluated by flow cytometry analysis using Annexin V/PI staining.

RESULTS

We found that the TES promoter was hypermethylated in GBM compared to normal brain tissues under DNA promoter methylation microarray analysis. The GBM patients with TES hypermethylation had a short overall survival (P <0.05, log-rank test). Among GBM samples, reduced TES protein level was detected in 33 (89.2%) of 37 tumor tissues by immunohistochemical staining. Down regulation of TES was also correlated with worse patient outcome (P <0.05, log-rank test). Treatment on the GBM cell line U251 with 5-aza-dC can greatly increase TES expression, confirming the hypermethylation of TES promoter in GBM. Up-regulation of TES prompts U251 apoptosis significantly. This study demonstrated that both TES promoter hypermethylation and down-regulated protein expression significantly correlated with worse patient outcome. Treatment on the GBM cell line (U251) with 5-aza-dC can highly release TES expression resulting in significant apoptosis in these cells.

CONCLUSIONS

Our findings suggest that the TES gene is a novel tumor suppressor gene and might represent a valuable prognostic marker for glioblastoma, indicating a potential target for future GBM therapy.

Gene co-expression network and function modules in three types of glioma

The aim of the present study was to identify the disease‑associated genes and their functions involved in the development of three types of glioma (astrocytoma, glioblastoma and oligodendroglioma) with DNA microarray technology, and to analyze their differences and correlations. First, the gene expression profile GSE4290 was downloaded from the Gene Expression Omnibus database, then the probe‑level data were pre‑processed and the differentially expressed genes (DEGs) were identified with limma package in R language. Gene functions of the selected DEGs were further analyzed with the Database for Annotation, Visualization and Integrated Discovery. After the co‑expression network of DEGs was constructed by Cytoscape, the functional modules were mined and enrichment analysis was performed, and then the similarities and differences between any two types of glioma were compared. A total of 1151 genes between normal and astrocytoma tissues, 684 genes between normal and malignant glioma tissues, and 551 genes between normal and oligodendroglioma tissues were filtered as DEGs, respectively. By constructing co‑expression networks of DEGs, a total of 77232, 455 and 987 interactions were involved in the differentially co‑expressed networks of astrocytoma, oligodendroglioma and glioblastoma, respectively. The functions of DEGs were consistent with the modules in astrocytoma, glioblastoma and oligodendroglioma, which were mainly enriched in neuron signal transmission, immune responses and synthesis of organic acids, respectively. Model functions of astrocytoma and glioblastoma were similar (mainly related with immune response), while the model functions of oligodendroglioma differed markedly from that of the other two types. The identification of the associations among these three types of glioma has potential clinical utility for improving the diagnosis of different types of glioma in the future. In addition, these results have marked significance in studying the underlying mechanisms, distinguishing between normal and cancer tissues, and examining novel therapeutic strategies for patients with glioma.

Actions of the protein kinase WNK1 on endothelial cells are differentially mediated by its substrate kinases OSR1 and SPAK

The with no lysine (K) (WNK) family of enzymes is best known for control of blood pressure through regulation of the function and membrane localization of ion cotransporters. In mice, global as well as endothelial-specific WNK1 gene disruption results in embryonic lethality due to angiogenic and cardiovascular defects. WNK1(-/-) embryos can be rescued by endothelial-specific expression of a constitutively active form of the WNK1 substrate protein kinase OSR1 (oxidative stress responsive 1). Using human umbilical vein endothelial cells (HUVECs), we explored mechanisms underlying the requirement of WNK1-OSR1 signaling for vascular development. WNK1 is required for cord formation in HUVECs, but the actions of the two major WNK1 effectors, OSR1 and its close relative SPAK (STE20/SPS1-related proline-, alanine-rich kinase), are distinct. SPAK is important for endothelial cell proliferation, whereas OSR1 is required for HUVEC chemotaxis and invasion. We also identified the zinc-finger transcription factor Slug in WNK1-mediated control of endothelial functions. Our study identifies a separation of functions for the WNK1-activated protein kinases OSR1 and SPAK in mediating proliferation, invasion, and gene expression in endothelial cells and an unanticipated link between WNK1 and Slug that is important for angiogenesis.

Stability of the CpG island methylator phenotype during glioma progression and identification of methylated loci in secondary glioblastomas

Background

Grade IV glioblastomas exist in two forms, primary (de novo) glioblastomas (pGBM) that arise without precursor lesions, and the less common secondary glioblastomas (sGBM) which develop from earlier lower grade lesions. Genetic heterogeneity between pGBM and sGBM has been documented as have differences in the methylation of individual genes. A hypermethylator phenotype in grade IV GBMs is now well documented however there has been little comparison between global methylation profiles of pGBM and sGBM samples or of methylation profiles between paired early and late sGBM samples.

Methods

We performed genome-wide methylation profiling of 20 matched pairs of early and late gliomas using the Infinium HumanMethylation450 BeadChips to assess methylation at >485,000 cytosine positions within the human genome.

Results

Clustering of our data demonstrated a frequent hypermethylator phenotype that associated with IDH1 mutation in sGBM tumors. In 80% of cases, the hypermethylator status was retained in both the early and late tumor of the same patient, indicating limited alterations to genome-wide methylation during progression and that the CIMP phenotype is an early event. Analysis of hypermethylated loci identified 218 genes frequently methylated across grade II, III and IV tumors indicating a possible role in sGBM tumorigenesis. Comparison of our sGBM data with TCGA pGBM data indicate that IDH1 mutated GBM samples have very similar hypermethylator phenotypes, however the methylation profiles of the majority of samples with WT IDH1 that do not demonstrate a hypermethylator phenotype cluster separately from sGBM samples, indicating underlying differences in methylation profiles. We also identified 180 genes that were methylated only in sGBM. Further analysis of these genes may lead to a better understanding of the pathology of sGBM vs pGBM.

Conclusion

This is the first study to have documented genome-wide methylation changes within paired early/late astrocytic gliomas on such a large CpG probe set, revealing a number of genes that maybe relevant to secondary gliomagenesis.

T-box transcription factor brachyury is associated with prostate cancer progression and aggressiveness

PURPOSE

Successful therapy of patients with prostate cancer is highly dependent on reliable diagnostic and prognostic biomarkers. Brachyury is considered a negative prognostic factor in colon and lung cancer; however, there are no reports on Brachyury's expression in prostate cancer.

EXPERIMENTAL DESIGN

In this study, we aimed to assess the impact of Brachyury expression in prostate tumorigenesis using a large series of human prostate samples comprising benign tissue, prostate intraepithelial neoplasia (PIN) lesions, localized tumor, and metastatic tissues. The results obtained were compared with what can be inferred from the Oncomine database. In addition, multiple in vitro models of prostate cancer were used to dissect the biologic role of Brachyury in prostate cancer progression.

RESULTS

We found that Brachyury is significantly overexpressed in prostate cancer and metastatic tumors when compared with normal tissues, both at protein and at mRNA levels. Brachyury expression in the cytoplasm correlates with highly aggressive tumors, whereas the presence of Brachyury in the nucleus is correlated with tumor invasion. We found that Brachyury-positive cells present higher viability, proliferation, migration, and invasion rates than Brachyury-negative cells. Microarray analysis further showed that genes co-expressed with Brachyury are clustered in oncogenic-related pathways, namely cell motility, cell-cycle regulation, and cell metabolism.

CONCLUSIONS

Collectively, the present study suggests that Brachyury plays an important role in prostate cancer aggressiveness and points, for the first time, to Brachyury as a significant predictor of poor prostate cancer prognosis. Our work paves the way for future studies assessing Brachyury as a possible prostate cancer therapeutic target.

In Vitro and In Vivo Analysis of RTK Inhibitor Efficacy and Identification of Its Novel Targets in Glioblastomas

Treatment for glioblastoma consists of radiotherapy and temozolomide-based chemotherapy. However, virtually all patients recur, leading to a fatal outcome. Receptor tyrosine kinase (RTK)-targeted therapy has been the focus of attention in novel treatment options for these patients. Here, we compared the efficacy of imatinib, sunitinib, and cediranib in glioblastoma models. In the present work, the biologic effect of the drugs was screened by viability, cell cycle, apoptosis, migration, and invasion in vitro assays or in vivo by chick chorioallantoic membrane assay. Intracellular signaling was assessed by Western blot and the RTK targets were identified using phospho-RTK arrays. The amplified status of KIT, PDGFRA, and VEGFR2 genes was assessed by quantitative polymerase chain reaction. In a panel of 10 glioblastoma cell lines, we showed that cediranib was the most potent. In addition, cediranib and sunitinib synergistically sensitize the cells to temozolomide. Cediranib efficacy was shown to associate with higher cytostatic and unique cytotoxic effects in vitro and both antitumoral and antiangiogenic activity in vivo, which could associate with its great capacity to inhibit mitogen-activated protein kinase (MAPK) and AKT pathways. The molecular status of KIT, PDGFRA, and VEGFR2 did not predict glioblastoma cell responsiveness to any of the RTK inhibitors. Importantly, phospho-RTK arrays revealed novel targets for cediranib and sunitinib therapy. In conclusion, the novel targets found may be of value as future biomarkers for therapy response in glioblastoma and lead to the rational selection of patients for effective molecular targeted treatment.

RKIP inhibition in cervical cancer is associated with higher tumor aggressive behavior and resistance to cisplatin therapy

Cervical cancer is one of the most common cancers in women worldwide, being high-risk group the HPV infected, the leading etiological factor. The raf kinase inhibitory protein (RKIP) has been associated with tumor progression and metastasis in several human neoplasms, however its role on cervical cancer is unclear. In the present study, 259 uterine cervix tissues, including cervicitis, cervical intraepithelial lesions and carcinomas, were analyzed for RKIP expression by immunohistochemistry. We found that RKIP expression was significantly decreased during malignant progression, being highly expressed in non-neoplastic tissues (54% of the samples; 73/135), and expressed at low levels in the cervix invasive carcinomas (∼15% (19/124). Following in vitro downregulation of RKIP, we observed a viability and proliferative advantage of RKIP-inhibited cells over time, which was associated with an altered cell cycle distribution and higher colony number in a colony formation assay. An in vitro wound healing assay showed that RKIP abrogation is associated with increased migratory capability. RKIP downregulation was also associated with an increased vascularization of the tumors in vivo using a CAM assay. Furthermore, RKIP inhibition induced cervical cancer cells apoptotic resistance to cisplatin treatment. In conclusion, we described that RKIP protein is significantly depleted during the malignant progression of cervical tumors. Despite the lack of association with patient clinical outcome, we demonstrate, in vitro and in vivo, that loss of RKIP expression can be one of the factors that are behind the aggressiveness, malignant progression and chemotherapy resistance of cervical cancer.

Monocarboxylate transporters (MCTs) in gliomas: expression and exploitation as therapeutic targets

BACKGROUND

Gliomas exhibit high glycolytic rates, and monocarboxylate transporters (MCTs) play a major role in the maintenance of the glycolytic metabolism through the proton-linked transmembrane transport of lactate. However, their role in gliomas is poorly studied. Thus, we aimed to characterize the expression of MCT1, MCT4, and their chaperone CD147 and to assess the therapeutic impact of MCT inhibition in gliomas.

METHODS

MCTs and CD147 expressions were characterized by immunohistochemistry in nonneoplastic brain and glioma samples. The effect of CHC (MCT inhibitor) and MCT1 silencing was assessed in in vitro and in vivo glioblastoma models.

RESULTS

MCT1, MCT4, and CD147 were overexpressed in the plasma membrane of glioblastomas, compared with diffuse astrocytomas and nonneoplastic brain. CHC decreased glycolytic metabolism, migration, and invasion and induced cell death in U251 cells (more glycolytic) but only affected proliferation in SW1088 (more oxidative). The effectiveness of CHC in glioma cells appears to be dependent on MCT membrane expression. MCT1 downregulation showed similar effects on different glioma cells, supporting CHC as an MCT1 inhibitor. There was a synergistic effect when combining CHC with temozolomide treatment in U251 cells. In the CAM in vivo model, CHC decreased the size of tumors and the number of blood vessels formed.

CONCLUSIONS

This is the most comprehensive study reporting the expression of MCTs and CD147 in gliomas. The MCT1 inhibitor CHC exhibited anti-tumoral and anti-angiogenic activity in gliomas and, of importance, enhanced the effect of temozolomide. Thus, our results suggest that development of therapeutic approaches targeting MCT1 may be a promising strategy in glioblastoma treatment.