Intersex-like (IXL) is a cell survival regulator in pancreatic cancer with 19q13 amplification

Traumatic brain injury promotes neurogenesis at the cost of astrogliogenesis in the adult hippocampus of male mice

Traumatic brain injury (TBI) can result in long-lasting changes in hippocampal function. The changes induced by TBI on the hippocampus contribute to cognitive deficits. The adult hippocampus harbors neural stem cells (NSCs) that generate neurons (neurogenesis), and astrocytes (astrogliogenesis). While deregulation of hippocampal NSCs and neurogenesis have been observed after TBI, it is not known how TBI may affect hippocampal astrogliogenesis. Using a controlled cortical impact model of TBI in male mice, single cell RNA sequencing and spatial transcriptomics, we assessed how TBI affected hippocampal NSCs and the neuronal and astroglial lineages derived from them. We observe an increase in NSC-derived neuronal cells and a concomitant decrease in NSC-derived astrocytic cells, together with changes in gene expression and cell dysplasia within the dentate gyrus. Here, we show that TBI modifies NSC fate to promote neurogenesis at the cost of astrogliogenesis and identify specific cell populations as possible targets to counteract TBI-induced cellular changes in the adult hippocampus.

High Level of GMFG Correlated to Poor Clinical Outcome and Promoted Cell Migration and Invasion through EMT Pathway in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) has a very poor prognosis due to the disease's lack of established targeted treatment options. Glia maturation factor γ (GMFG), a novel ADF/cofilin superfamily protein, has been reported to be differentially expressed in tumors, but its expression level in TNBC remains unknown. The question of whether GMFG correlates with the TNBC prognosis is also unclear. In this study, data from the Cancer Genome Atlas (TCGA), Clinical Proteomic Tumor Analysis Consortium (CPTAC), Human Protein Atlas (HPA), and Genotype-Tissue Expression (GTEx) databases were used to analyze the expression of GMFG in pan-cancer and the correlation between clinical factors. Gene Set Cancer Analysis (GSCA) and Gene Set Enrichment Analysis (GSEA) were also used to analyze the functional differences between the different expression levels and predict the downstream pathways. GMFG expression in breast cancer tissues, and its related biological functions, were further analyzed by immunohistochemistry (IHC), immunoblotting, RNAi, and function assay; we found that TNBC has a high expression of GMFG, and this higher expression was correlated with a poorer prognosis in TCGA and collected specimens of the TNBC. GMFG was also related to TNBC patients' clinicopathological data, especially those with histological grade and axillary lymph node metastasis. In vitro, GMFG siRNA inhibited cell migration and invasion through the EMT pathway. The above data indicate that high expression of GMFG in TNBC is related to malignancy and that GMFG could be a biomarker for the detection of TNBC metastasis.

A novel tRNA-derived fragment AS-tDR-007333 promotes the malignancy of NSCLC via the HSPB1/MED29 and ELK4/MED29 axes

Background

Transfer RNA-derived fragments (tRFs) are a new class of small non-coding RNAs. Recent studies suggest that tRFs participate in some pathological processes. However, the biological functions and mechanisms of tRFs in non-small cell lung cancer (NSCLC) are largely unknown.

Methods

Differentially expressed tRFs were identified by tRF and tiRNA sequencing using 9 pairs of pre- and post-operation plasma from patients with NSCLC. Quantitative real-time PCR (qRT-PCR) and fluorescence in situ hybridization (FISH) were used to determine the levels of tRF in tissues, plasma, and cells. Gain- and loss-of-function experiments were implemented to investigate the oncogenic effects of tRF on NSCLC cells in vitro and in vivo. Chromatin immunoprecipitation (ChIP), luciferase reporter, RNA pulldown, mass spectrum, RNA immunoprecipitation (RIP), Western blot, co-immunoprecipitation (Co-IP) assays, and rescue experiments were performed to explore the regulatory mechanisms of tRF in NSCLC.

Results

AS-tDR-007333 was an uncharacterized tRF and significantly up-regulated in NSCLC tissues, plasma, and cells. Clinically, AS-tDR-007333 overexpression could distinguish NSCLC patients from healthy controls and associated with poorer prognosis of NSCLC patients. Functionally, overexpression of AS-tDR-007333 enhanced proliferation and migration of NSCLC cells, whereas knockdown of AS-tDR-007333 resulted in opposite effects. Mechanistically, AS-tDR-007333 promoted the malignancy of NSCLC cells by activating MED29 through two distinct mechanisms. First, AS-tDR-007333 bound to and interacted with HSPB1, which activated MED29 expression by enhancing H3K4me1 and H3K27ac in MED29 promoter. Second, AS-tDR-007333 stimulated the expression of transcription factor ELK4, which bound to MED29 promoter and increased its transcription. Therapeutically, inhibition of AS-tDR-007333 suppressed NSCLC cell growth in vivo.

Conclusions

Our study identifies a new oncogenic tRF and uncovers a novel mechanism that AS-tDR-007333 promotes NSCLC malignancy through the HSPB1-MED29 and ELK4-MED29 axes. AS-tDR-007333 is a potential diagnostic or prognostic marker and therapeutic target for NSCLC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-022-01270-y.

Cyclin-Dependent Kinases (CDK) and Their Role in Diseases Development-Review

Cyclin-dependent kinases (CDKs) are involved in many crucial processes, such as cell cycle and transcription, as well as communication, metabolism, and apoptosis. The kinases are organized in a pathway to ensure that, during cell division, each cell accurately replicates its DNA, and ensure its segregation equally between the two daughter cells. Deregulation of any of the stages of the cell cycle or transcription leads to apoptosis but, if uncorrected, can result in a series of diseases, such as cancer, neurodegenerative diseases (Alzheimer’s or Parkinson’s disease), and stroke. This review presents the current state of knowledge about the characteristics of cyclin-dependent kinases as potential pharmacological targets.

The DYRK Family of Kinases in Cancer: Molecular Functions and Therapeutic Opportunities

DYRK (dual-specificity tyrosine-regulated kinases) are an evolutionary conserved family of protein kinases with members from yeast to humans. In humans, DYRKs are pleiotropic factors that phosphorylate a broad set of proteins involved in many different cellular processes. These include factors that have been associated with all the hallmarks of cancer, from genomic instability to increased proliferation and resistance, programmed cell death, or signaling pathways whose dysfunction is relevant to tumor onset and progression. In accordance with an involvement of DYRK kinases in the regulation of tumorigenic processes, an increasing number of research studies have been published in recent years showing either alterations of DYRK gene expression in tumor samples and/or providing evidence of DYRK-dependent mechanisms that contribute to tumor initiation and/or progression. In the present article, we will review the current understanding of the role of DYRK family members in cancer initiation and progression, providing an overview of the small molecules that act as DYRK inhibitors and discussing the clinical implications and therapeutic opportunities currently available.

Whole Exome and Transcriptome RNA-Sequencing Model for the Diagnosis of Prostate Cancer

In our previous study, we developed a genome-wide DNA methylation model for the diagnosis of prostate cancer, and we pointed out that a considerable average error is associated with the current method for the diagnosis of prostate cancer, which is predicated on pathological assessment of biopsied tissue. In this study, we utilized whole exome and transcriptome RNA-sequencing (RNA-seq) data that were derived from 468 tumor samples and 51 normal samples of prostatic tissue, and we analyzed over 20,000 genes per sample. We were able to develop a mathematical model that classified tumor tissue versus normal tissue with a high accuracy. The overall sensitivity was 97.01%, and the overall specificity was 94.12%. The input variables to the model were the mRNA expression values of the following nine genes: ANGPT1, MED21, AOX1, PLP2, HPN, HPN-AS1, EPHA10, NKX2-3, and LRFN1. The model was validated with unknown samples, with a 10-fold cross-validation, and a leave-one-out cross-validation. We present here a genomic model, based on a whole exome and transcriptome RNA-seq analysis of biopsied prostatic tissue, that could be utilized in the diagnosis of prostate cancer.

Targeting the Ribosome Biogenesis Key Molecule Fibrillarin to Avoid Chemoresistance

Background:

Inherent or acquired chemo resistance in cancer patients has been a perpetual limitation in cancer treatment. Expanding knowledge on essential cellular processes opens a new window for therapeutic targeting. Ribosome biogenesis is a process that shows potential due to its fundamental role in cell development and contribution to tumorigenesis as a result of its upregulation. Inhibiting components of ribosome biogenesis has been explored and has shown interesting results. Yet, an important key component, methyltransferase Fibrillarin (FBL), which influences both the abundance and composition of ribosomes, has not been exploited thus far.

Methods:

In this literature review, we describe relevant aspects of ribosome biogenesis in cancer to emphasize the potential of FBL as a therapeutic target, in order to lower the genotoxic effects of anti-cancer treatment.

Results:

Remarkably, the amplification of the 19q13 cytogenetic band, including the gene coding for FBL, correlated to cell viability and resistance in pancreatic cells as well as to a trend toward a shorter survival in pancreatic cancer patients.

:

Targeting ribosome biogenesis, more specifically compared to the secondary effects of chemotherapeutics such as 5-fluorouracil or oxaliplatin, has been achieved by compound CX-5461. The cell dependent activity of this Pol I inhibitor has been reported in ovarian cancer, melanoma and leukemia models with active or mutated p53 status, presenting a promising mechanism to evade p53 resistance.

Conclusion:

Targeting critical ribosome biogenesis components in order to decrease the genotoxic activity in cancer cell looks promising. Hence, we believe that targeting key protein rRNA methyltransferase FBL shows great potential, due to its pivotal role in ribosome biogenesis, its correlation to an improved survival rate at low expression in breast cancer patients and its association with p53.

Increased mediator complex subunit CDK19 expression associates with aggressive prostate cancer

The Mediator complex is a transcriptional regulator interacting with transcription factors and RNA-polymerase-II. Recently, we identified its subunit CDK19 to be specifically expressed in prostate cancer (PCa) and to be functionally implicated in PCa aggressiveness. Aim of our study was to comprehensively characterize the protein expression of CDK19 and its paralog CDK8 in PCa. We performed immunohistochemistry (IHC) for CDK19/CDK8 on a large cohort including needle biopsies from 202 patients, 799 primary tumor foci of radical prostatectomy specimens from 415 patients, 120 locally advanced tumor foci obtained by palliative transurethral resection, 140 lymph node metastases, 67 distant metastases and 82 benigns. Primary tumors were stained for the proliferation marker Ki67, androgen receptor (AR) and ERG. For 376 patients, clinic-pathologic data were available. Primary endpoint was disease-recurrence-free survival (DFS). Nuclear CDK19 and CDK8 expression increases during progression showing the highest intensity in metastatic and castration-resistant tumors. High CDK19 expression on primary tumors correlates with DFS independently from Gleason grade and PSA. Five-year-DFS rates of patients with primary tumors expressing no, moderate and high CDK19 are 73.7, 56.9 and 30.4%, respectively. CDK19 correlates with Gleason grade, T-stage, Ki67 proliferation-index, nuclear AR expression and ERG-status. Therapeutic options for metastatic and castration-resistant PCa remain limited. In the current study, we confirmed an important role of the Mediator subunit CDK19 in advanced PCa supporting current developments to target CDK19 and its paralog CDK8. Furthermore, CDK19 protein expression has the potential to predict disease recurrence independently from established biomarkers thus contributing to individual management for PCa patients.

High SALM3 Expression in Tumor Cells and Fibroblasts Is Correlated with Poor Prognosis in Gastric Cancer Patients

Objective

The synaptic adhesion-like molecule (SALM) family is largely restricted to neural tissues and is involved in the regulation of neurite outgrowth and synapse formation. However, the expression of SALM3 in gastric cancer (GC) and its clinical significance remain unclear. The aim of the present study was to investigate the prognostic value of SALM3 in patients with GC.

Patients and Methods

Expression of SALM3 was validated by tissue microarrays from 730 GC patients and statistically assessed for correlations with the clinical parameters and the prognosis of the patients. The transcriptional and survival data of SALM3 in GC patients were also mined through the Oncomine and Kaplan-Meier Plotter databases.

Results

SALM3 is overexpressed in the tumor cells and fibroblasts of clinical GC tissues, and a high level of SALM3 was significantly associated with tumor invasive characteristics. Cox proportional hazards univariate and multivariate regression analyses revealed SALM3 expression in tumor cells or stroma as an independent prognostic factor in the overall survival rate of GC patients. Furthermore, the survival of GC patients with high SALM3 expression in both tumor cells and fibroblasts was significantly poorer than that of the other groups. Oncomine and Kaplan-Meier Plotter analyses further confirmed high levels of SALM3 expression in GC, and high levels of SALM3 expression were associated with shorter survival in patients.

Conclusion

SALM3 may be a prognostic factor for GC and may potentially be a high-priority therapeutic target.

Up-regulation of Dyrk1b promote astrocyte activation following lipopolysaccharide-induced neuroinflammation

Astrocytes become activated in response to different stimulation. Dyrk1b is an arginine-directed serine/threonineprotein kinase that is expressed at elevated levels in many cancers but remains unknown in the pathologies of neuroinflammation. In this study, in vivo, we demonstrated that Dyrk1b expression was significantly increased and reached a peak at 12 h after LPS injection via Western blot. Double immunofluorescence staining showed that Dyrk1b co-located with GFAP and Ki67. In vitro, the expression of Dyrk1b, Ki67 and cyclinD1 was gradually increased and reached a peak at 12 h in a time-dependent manner after 1 μg/mL LPS stimulation. Knockdown of Dyrk1b significantly reduced the expression of Ki67 and cyclinD1. In addition, the data exhibited that silenced Dyrk1b decreased the expression of p-STAT3 in primary astrocyte cells, and Dyrk1b interacted with STAT3 in LPS-induced neuroinflammation. In conclusion, these results suggested that Dyrk1b is increased and may play a crucial role in regulating astrocyte cell activation via interact with STAT3 in LPS-induced neuroinflammation.

A wake-up call to quiescent cancer cells - potential use of DYRK1B inhibitors in cancer therapy

Nondividing cancer cells are relatively resistant to chemotherapeutic drugs and environmental stress factors. Promoting cell cycle re-entry of quiescent cancer cells is a potential strategy to enhance the cytotoxicity of agents that target cycling cells. It is therefore important to elucidate the mechanisms by which these cells are maintained in the quiescent state. The protein kinase dual specificity tyrosine phosphorylation-regulated kinase 1B (DYRK1B) is overexpressed in a subset of cancers and maintains cellular quiescence by counteracting G0 /G1 -S phase transition. Specifically, DYRK1B controls the S phase checkpoint by stabilizing the cyclin-dependent kinase (CDK) inhibitor p27Kip1 and inducing the degradation of cyclin D. DYRK1B also stabilizes the DREAM complex that represses cell cycle gene expression in G0 arrested cells. In addition, DYRK1B enhances cell survival by upregulating antioxidant gene expression and reducing intracellular levels of reactive oxygen species (ROS). Substantial evidence indicates that depletion or inhibition of DYRK1B drives cell cycle re-entry and enhances apoptosis of those quiescent cancer cells with high expression of DYRK1B. Furthermore, small molecule DYRK1B inhibitors sensitize cells to the cytotoxic effects of anticancer drugs that target proliferating cells. These encouraging findings justify continued efforts to investigate the use of DYRK1B inhibitors to disrupt the quiescent state and overturn chemoresistance of noncycling cancer cells.

Prognostic significance of anti-diabetic medications in pancreatic cancer: A meta-analysis

The role of anti-diabetic medications in pancreatic cancer remains conflicting. We carried out a systematic search of Pubmed and Embase databases for studies published before August 2016, which assessed the associations between anti-diabetic medications (metformin, sulfonylureas, thiazolidinediones and insulin) intake and pancreatic cancer prognosis. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using the random-effects model. The primary outcomes of interest were overall survival (OS) and progression-free survival (PFS). Fourteen studies enrolling 94778 participants were eligible for inclusion, with 12 cohort studies and 2 randomized controlled trials (RCTs). Significant association between metformin (adjusted HR=0.77, 95% CI=0.68-0.87) use and OS was found in cohort studies, whereas no significant association between metformin use and PFS (HR=1.22; 95% CI=0.76-1.95) or OS (HR=1.20, 95% CI=0.84-1.72) in RCTs. No significant survival benefits were identified for insulin (HR=1.18, 95% CI=0.83-1.69), sulfonylureas (HR=1.03, 95% CI=0.81-1.30), or thiazolidinediones (HR=0.84, 95% CI=0.58-1.22). The trim-and-fill method and subgroup analyses stratified by the study characteristics confirmed the robustness of the results. Our findings provide strong evidence that metformin is associated with improved OS in pancreatic cancer patients in cohort studies. However, the effect of other anti-diabetic medications should be interpreted with caution owing to the limited number of studies.

Surface-bound galectin-4 regulates gene transcription and secretion of chemokines in human colorectal cancer cell lines

One long-term complication of chronic intestinal inflammation is the development of colorectal cancer. However, the mechanisms linking inflammation to the colorectal tumorigenesis are poorly defined. Previously, we have demonstrated that galectin-4 is predominantly expressed in the luminal epithelia of the gastrointestinal tract, and its loss of expression plays a key role in the colorectal tumorigenesis. However, the mechanism by which galectin-4 regulates inflammation-induced tumorigenesis is unclear. Here, we show that galectin-4 secreted by the colorectal cancer cell lines was bound to the cell surface. Neutralization of surface-bound galectin-4 with anti-galectin-4 antibody resulted in increased cell proliferation with concomitant secretion of several chemokines into the extracellular medium. Neutralization of the surface-bound galectin-4 also resulted in the up-regulation of transcription of 29 genes, several of which are components of multiple inflammation signaling pathways. In an alternate experiment, binding of recombinant galectin-4 protein to cell surface of the galectin-4-negative colorectal cancer cells resulted in increased p27, and decreased cyclin D1 and c-Myc levels, leading to cell cycle arrest and apoptosis. Together, these data demonstrated that surface-bound galectin-4 is a dual function protein-down-regulating cell proliferation and chemokine secretion in galectin-4-expressing colorectal cancer cells on one hand and inducing apoptosis in galectin-4-negative colorectal cancer cells on the other hand.

Identification of DYRK1B as a substrate of ERK1/2 and characterisation of the kinase activity of DYRK1B mutants from cancer and metabolic syndrome

The dual-specificity tyrosine-phosphorylation-regulated kinase, DYRK1B, is expressed de novo during myogenesis, amplified or mutated in certain cancers and mutated in familial cases of metabolic syndrome. DYRK1B is activated by cis auto-phosphorylation on tyrosine-273 (Y273) within the activation loop during translation but few other DYRK1B phosphorylation sites have been characterised to date. Here, we demonstrate that DYRK1B also undergoes trans-autophosphorylation on serine-421 (S421) in vitro and in cells and that this site contributes to DYRK1B kinase activity. Whilst a DYRK1B(S421A) mutant was completely defective for p-S421 in cells, DYRK1B inhibitors caused only a partial loss of p-S421 suggesting the existence of an additional kinase that could also phosphorylate DYRK1B S421. Indeed, a catalytically inactive DYRK1B(D239A) mutant exhibited very low levels of p-S421 in cells but this was increased by KRAS(G12V). In addition, selective activation of the RAF-MEK1/2-ERK1/2 signalling pathway rapidly increased p-S421 in cells whereas activation of the stress kinases JNK or p38 could not. S421 resides within a Ser-Pro phosphoacceptor motif that is typical for ERK1/2 and recombinant ERK2 phosphorylated DYRK1B at S421 in vitro. Our results show that DYRK1B is a novel ERK2 substrate, uncovering new links between two kinases involved in cell fate decisions. Finally, we show that DYRK1B mutants that have recently been described in cancer and metabolic syndrome exhibit normal or reduced intrinsic kinase activity.

Overexpression of PD2 leads to increased tumorigenicity and metastasis in pancreatic ductal adenocarcinoma

Pancreatic differentiation 2 (PD2), an important subunit of the human PAF complex, was identified after differential screening analysis of 19q13 amplicon, and its overexpression induces oncogenic transformation of NIH3T3 cells, hence raising the possibility of a role for PD2 in tumorigenesis and metastasis. To test this hypothesis, we analyzed here the functional role and clinical significance of PD2 in pancreatic ductal adenocarcinoma (PDAC) and its pathogenesis. Using immunohistochemical analysis, we found that PD2 is detected in the acini but not in the ducts in the normal pancreas. In human PDAC specimens, PD2 was instead primarily detected in the ducts (12/48 patients 25%; p-value < 0.0001), thereby showing that PDAC correlates with increased ductal expression of PD2. Consistently, PD2 expression was increased in telomerase-immortalized human pancreatic ductal cells (HPNE cells) modified to express the HPV16 E6 and E7 proteins, whose respective functions are to block p53 and RB. In addition, ectopic expression of PD2 in PDAC cells (Capan-1 and SW1990) led to increased clonogenicity and migration in vitro, and tumor growth and metastasis in vivo. Interestingly, PD2 overexpression also resulted in enrichment of cancer stem cells (CSCs) and upregulation of oncogenes such as c-Myc and cell cycle progression marker, cyclin D1. Taken together, our results support that PD2 is overexpressed in the ducts of PDAC tissues, and results in tumorigenesis and metastasis via upregulation of oncogenes such as c-Myc and cyclin hence D1 implicating PD2 upregulation in pancreatic oncogenesis with targeted therapeutic potential.

Genome-wide copy number changes and CD133 expression characterized distinct subset of colon polyps: differentiation between incidental polyps and cancer-associated polyps

PURPOSE

Colorectal polyps are generally believed to be the precursors of colorectal cancers (CRC); however, the proportion and speed of progression differed widely in different subsets of polyps. Using microarray-based comparative genomic hybridization (aCGH) platform and CD133 immunostaining, we characterized colon polyps according to their association with CRC that developed in the same individual.

PATIENTS AND METHODS

aCGH was performed to unveil genomic changes in 18 cancer-synchronous polyps (CSP), and 9 cancer-preceding polyps (CPP), together with their corresponding cancers and 16 cases of incidental polyps (IP), were examined for comparison. aCGH profiles were analyzed to determine the clonal relationship (CR) between the paired adenoma and carcinoma. CD133 expressions in each subset of polyps were quantified by immunohistochemistry (IHC) staining.

RESULTS

Progressive genomic changes were observed from IP, CSP/CPP to CRC; they encompass an entire chromosomal region in IP and sub-chromosomal region in CSP/CPP and CRC. CR analyses demonstrated that 50 % of CSP and 67 % of CPP were clonally related to the concurrent or later developed carcinomas, respectively. The CD133 expression levels were significantly higher in CSP/CPP than those in IP (P < 0.0001) and even higher in CSP/CPP that were clonally related to their corresponding carcinomas than CSP/CPP that were unrelated (P < 0.05).

CONCLUSIONS

There were more genomic changes in CSP/CPP than IP; more than half of the CSP/CPP were clonally related to the corresponding carcinomas. Genomic changes at sub-chromosomal regions and/or high CD133 expression were associated with CSP/CPP and highlighted their carcinogenic potential.

The Impact of Diabetes Mellitus and Metformin Treatment on Survival of Patients with Advanced Pancreatic Cancer Undergoing Chemotherapy

PURPOSE

A causal relationship between diabetes mellitus (DM) and pancreatic cancer is well established. However, in patients with advanced pancreatic cancer (APC) who receive palliative chemotherapy, the impact of DM on the prognosis of APC is unclear.

MATERIALS AND METHODS

We retrospectively enrolled APC patients who received palliative chemotherapy between 2003 and 2010. The patients were stratified according to the status of DM, in accordance with 2010 DM criteria (American Heart Association/American Diabetes Association). DM at least 2 years' duration prior to diagnosis of APC was defined as remote-onset DM (vs. recent-onset).

RESULTS

Of the 349 APC patients, 183 (52.4%) had DM. Among the patients with DM, 160 patients had DM at the time of diagnosis of APC (remote-onset, 87; recent-onset, 73) and the remaining 23 patients developed DM during treatment of APC. Ultimately, 73.2% of patients (134/183) with DM received antidiabetic medication, including metformin (56 patients, 41.8%), sulfonylurea (62, 45.5%), and insulin (43, 32.1%). In multivariate analysis, cancer extent (hazard ratio [HR], 1.792; 95% confidence interval [CI], 1.313 to 2.445; p < 0.001) showed association with decreased overall survival (OS), whereas a diagnosis of DM (HR, 0.788; 95% CI, 0.615 to 1.009; p=0.059) conferred positive tendency on the OS. Metformin treatment itself conferred better OS in comparison within DM patients (HR 0.693; 95% CI, 0.492 to 0.977; p=0.036) and even in all APC patients (adjusted HR, 0.697; 95% CI, 0.491 to 1.990; p=0.044).

CONCLUSION

For APC patients receiving palliative chemotherapy, metformin treatment is associated with longer OS. Patients with DM tend to survive longer than those without DM.

Genetic events that limit the efficacy of MEK and RTK inhibitor therapies in a mouse model of KRAS-driven pancreatic cancer

Mutated KRAS (KRAS*) is a fundamental driver in the majority of pancreatic ductal adenocarcinomas (PDAC). Using an inducible mouse model of KRAS*-driven PDAC, we compared KRAS* genetic extinction with pharmacologic inhibition of MEK1 in tumor spheres and in vivo. KRAS* ablation blocked proliferation and induced apoptosis, whereas MEK1 inhibition exerted cytostatic effects. Proteomic analysis evidenced that MEK1 inhibition was accompanied by a sustained activation of the PI3K-AKT-MTOR pathway and by the activation of AXL, PDGFRa, and HER1-2 receptor tyrosine kinases (RTK) expressed in a large proportion of human PDAC samples analyzed. Although single inhibition of each RTK alone or plus MEK1 inhibitors was ineffective, a combination of inhibitors targeting all three coactivated RTKs and MEK1 was needed to inhibit proliferation and induce apoptosis in both mouse and human low-passage PDAC cultures. Importantly, constitutive AKT activation, which may mimic the fraction of AKT2-amplified PDAC, was able to bypass the induction of apoptosis caused by KRAS* ablation, highlighting a potential inherent resistance mechanism that may inform the clinical application of MEK inhibitor therapy. This study suggests that combinatorial-targeted therapies for pancreatic cancer must be informed by the activation state of each putative driver in a given treatment context. In addition, our work may offer explanative and predictive power in understanding why inhibitors of EGFR signaling fail in PDAC treatment and how drug resistance mechanisms may arise in strategies to directly target KRAS.

Mirk/dyrk1B kinase is upregulated following inhibition of mTOR

The PI3K/PTEN/Akt/mTOR/p70S6K pathway is one of the most frequently deregulated signaling pathways in solid tumors and has a functional role in drug resistance. However, targeting this pathway leads to compensatory activation of several mediators of cell survival. Expression of the reactive oxygen species-controlling kinase Mirk/dyrk1B was increased severalfold by the mammalian target of rapamycin (mTOR) inhibitors RAD001, WYE354 and rapamycin, with less effect by the Akt inhibitors AZD5363 and MK-2206. Upregulation of Mirk messenger RNA (mRNA) expression was mediated by cyclic AMP response element binding protein (CREB) binding to two sites in the Mirk promoter upstream of the transcription start site and one site within exon 4. Depletion of CREB reduced Mirk expression, whereas depletion of mTOR increased it. Moreover, hydroxytamoxifen activation of an Akt-estrogen receptor construct blocked an increase in Mirk mRNA and protein. Addition of a Mirk/dyrk1B kinase inhibitor increased the sensitivity of Panc1 pancreatic cancer cells and three different ovarian cancer cell lines to the mTOR inhibitor RAD001. Targeting Mirk kinase could improve the utility of mTOR inhibitors and so presents an attractive drug target.

The normal function of the cancer kinase Mirk/dyrk1B is to reduce reactive oxygen species

Mirk kinase is a gene upregulated and sometimes amplified in pancreatic cancers and in ovarian cancers, but expressed at very low levels in most normal diploid cells except for skeletal muscle. The muscle cell function of Mirk kinase selected for by cancer cells is unknown. It is now shown that Mirk protein is expressed at low levels and is largely nuclear in cycling skeletal muscle C2C12 myoblasts, but is translocated to the cytoplasm and upregulated when myoblasts initiate differentiation, as shown by immunofluorescence staining and by cell fractionation. Either Mirk depletion or Mirk kinase inhibition increased ROS levels in cycling C2C12 myoblasts. However, Mirk protein is localized in the cytoplasm of mature muscle fibers, specifically in the fast twitch fibers of human skeletal muscle where toxic ROS levels are generated by muscle contraction. C2C12 myoblasts at high density in differentiation media fuse to form differentiated postmitotic myotubes that can contract. A Mirk kinase inhibitor induced a dose-dependent increase in ROS in this model for fast twitch fibers of human skeletal muscle. Efficient Mirk depletion in SU86.86 pancreatic cancer cells by an inducible shRNA decreased expression of eight antioxidant genes. Thus both cancer cells and differentiated myotubes utilize Mirk kinase to relieve oxidative stress.

Macrophage migration inhibitory factor is overexpressed in pancreatic cancer tissues and impairs insulin secretion function of β-cell

Background

Understanding the pathogenic mechanism of pancreatic cancer associated diabetes (PCDM) might help yield biomarkers for the early diagnosis of pancreatic cancer (PC) from population with new-onset diabetes. In the current study, we sought to determine the role of macrophage migration inhibitory factor (MIF) in PCDM pathogenesis.

Methods

The protein and mRNA levels of MIF in paraffin-embedded human PC samples, chronic pancreatitis specimens, and normal pancreas were measured by immunohistochemistry and quantitative reverse-transcriptase polymerase chain reaction. We measured serum levels of MIF in PC patients and controls. The biologic impacts of MIF overexpression on insulin secretion function of mice islets and β cells (HIT-T15) were investigated in vitro.

Results

MIF expression was significantly increased in pancreatic cancer tissues compared with chronic pancreatitis or normal pancreas specimens. The insulin secretion function of both islets and HIT-T15 cells was impaired by indirect co-cultured with PC cells or treated with conditioned media from them. Stable MIF knock-down significantly decreased the diabetogenic effect of PC cells, while MIF knock-in HPDE6 cells demonstrated a strong inhibitory effect on insulin secretion function of islets and HIT-T15 cells. MIF impaired βcell function by depressing the Ca²⁺ currents, decreasing L-type Ca²⁺ channel α1 subunit protein expression level, and enhancing p-Src activity. Mean serum level of MIF was significant higher in new-onset diabetes associated PC patients in comparison with other groups.

Conclusions

MIF is up-regulated in patients with pancreatic cancer and causes dysfunction of insulin secretion in β-cells.

High GMFG expression correlates with poor prognosis and promotes cell migration and invasion in epithelial ovarian cancer

OBJECTIVE

The aim of this study was to characterize the clinical significance of GMFG, a novel ADF/cofilin superfamily protein, and investigate its role in cell migration and invasion in epithelial ovarian cancer (EOC).

METHODS

The expression of GMFG in EOC tissues and ovarian cancer cell lines was evaluated by immunohistochemistry and immunoblotting respectively. The data were statistically analyzed for the associations of GMFG expression with clinicopathologic parameters and survival. In vitro cell migration and invasion assays were performed to determine the role of GMFG in cell migratory behaviors. The effect of GMFG on reorganization of actin cytoskeleton was investigated by immunostaining.

RESULTS

GMFG was overexpressed in EOC. Up-regulated GMFG expression was closely correlated with advanced FIGO stage and chemoresistance of the disease. EOC patients with higher GMFG expression showed poorer progression-free survival (PFS) and overall survival (OS). In vitro cellular assays revealed that GMFG promoted cell migration and invasion. GMFG expression altered actin cytoskeleton organization probably by interacting with the Arp2/3 complex.

CONCLUSION

GMFG expression independently predicts poorer prognosis in patients with EOC. Ectopic overexpression of GMFG contributes to the malignant biological behavior of ovarian cancer cells.

A novel DYRK1B inhibitor AZ191 demonstrates that DYRK1B acts independently of GSK3β to phosphorylate cyclin D1 at Thr(286), not Thr(288)

DYRK1B (dual-specificity tyrosine phosphorylation-regulated kinase 1B) is amplified in certain cancers and may be an oncogene; however, our knowledge of DYRK1B has been limited by the lack of selective inhibitors. In the present study we describe AZ191, a potent small molecule inhibitor that selectively inhibits DYRK1B in vitro and in cells. CCND1 (cyclin D1), a key regulator of the mammalian G1-S-phase transition, is phosphorylated on Thr(286) by GSK3β (glycogen synthase kinase 3β) to promote its degradation. DYRK1B has also been proposed to promote CCND1 turnover, but was reported to phosphorylate Thr(288) rather than Thr(286). Using in vitro kinase assays, phospho-specific immunoblot analysis and MS in conjunction with AZ191 we now show that DYRK1B phosphorylates CCND1 at Thr(286), not Thr(288), in vitro and in cells. In HEK (human embryonic kidney)-293 and PANC-1 cells (which exhibit DYRK1B amplification) DYRK1B drives Thr(286) phosphorylation and proteasome-dependent turnover of CCND1 and this is abolished by AZ191 or DYRK1B RNAi, but not by GSK3β inhibitors or GSK3β RNAi. DYRK1B expression causes a G1-phase cell-cycle arrest, but overexpression of CCND1 (wild-type or T286A) fails to overcome this; indeed, DYRK1B also promotes the expression of p21CIP1 (21 kDa CDK-interacting protein 1) and p27KIP1 (CDK-inhibitory protein 1). The results of the present study demonstrate for the first time that DYRK1B is a novel Thr(286)-CCND1 kinase that acts independently of GSK3β to promote CCND1 degradation. Furthermore, we anticipate that AZ191 may prove useful in defining further substrates and biological functions of DYRK1B.

Identification of cellular proteins that interact with human cytomegalovirus immediate-early protein 1 by protein array assay

Human cytomegalovirus (HCMV) gene expression during infection is characterized as a sequential process including immediate-early (IE), early (E), and late (L)-stage gene expression. The most abundantly expressed gene at the IE stage of infection is the major IE (MIE) gene that produces IE1 and IE2. IE1 has been the focus of study because it is an important protein, not only for viral gene expression but also for viral replication. It is believed that IE1 plays important roles in viral gene regulation by interacting with cellular proteins. In the current study, we performed protein array assays and identified 83 cellular proteins that interact with IE1. Among them, seven are RNA-binding proteins that are important in RNA processing; more than half are nuclear proteins that are involved in gene regulations. Tumorigenesis-related proteins are also found to interact with IE1, implying that the role of IE1 in tumorigenesis might need to be reevaluated. Unexpectedly, cytoplasmic proteins, such as Golgi autoantigen and GGA1 (both related to the Golgi trafficking protein), are also found to be associated with IE1. We also employed a coimmunoprecipitation assay to test the interactions of IE1 and some of the proteins identified in the protein array assays and confirmed that the results from the protein array assays are reliable. Many of the proteins identified by the protein array assay have not been previously reported. Therefore, the functions of the IE1-protein interactions need to be further explored in the future.

Involvement of Mediator complex in malignancy

Mediator complex (MED) is an evolutionarily conserved multiprotein, fundamental for growth and survival of all cells. In eukaryotes, the mRNA transcription is dependent on RNA polymerase II that is associated to various molecules like general transcription factors, MED subunits and chromatin regulators. To date, transcriptional machinery dysfunction has been shown to elicit broad effects on cell proliferation, development, differentiation, and pathologic disease induction, including cancer. Indeed, in malignant cells, the improper activation of specific genes is usually ascribed to aberrant transcription machinery. Here, we focus our attention on the correlation of MED subunits with carcinogenesis. To date, many subunits are mutated or display altered expression in human cancers. Particularly, the role of MED1, MED28, MED12, CDK8 and Cyclin C in cancer is well documented, although several studies have recently reported a possible association of other subunits with malignancy. Definitely, a major comprehension of the involvement of the whole complex in cancer may lead to the identification of MED subunits as novel diagnostic/prognostic tumour markers to be used in combination with imaging technique in clinical oncology, and to develop novel anti-cancer targets for molecular-targeted therapy.

Potential significance of EMP3 in patients with upper urinary tract urothelial carcinoma: crosstalk with ErbB2-PI3K-Akt pathway

PURPOSE

Upper urinary tract (pyelocalyceal cavities and ureter) urothelial carcinoma is a relatively rare neoplastic disease. Although diagnosis and treatment of this tumor variant have improved significantly, accurate risk stratification remains a challenge. To identify the putative oncogene involved in urothelial carcinoma progression we performed bioinformatics guided experimental investigation targeting chromosome 19q13.

MATERIALS AND METHODS

We investigated the effects of EMP3 on cancer cell growth, migration and adhesion in transfection and siRNA experiments in vitro. Crosstalk of integrins or ErbB2 with EMP3 was examined by reverse transcriptase-polymerase chain reaction and immunoblot. The potential involvement of epigenetic alterations of EMP3 in vitro and in vivo was analyzed by methylation specific polymerase chain reaction. To validate clinical relevance we measured EMP3 expression at the mRNA and protein levels in a cohort of 77 patients with upper urinary tract urothelial carcinoma and compared prognostic significance in relation to that of ErbB2 expression.

RESULTS

We noted functional crosstalk between ErbB2 and EMP3 in vitro. EMP3 over expression promoted cancer cell proliferation and migration but suppressed cell adhesion in vitro. EMP3 activated the ErbB2-PI3K-AKT pathway to increase cell growth in vitro. In the clinical cohort Kaplan-Meier survival estimates showed that ErbB2 and EMP3 co-expression was the most important indicator of progression-free and metastasis-free survival in patients with upper urinary tract urothelial carcinoma (log rank test p = 0.018 and 0.04, respectively).

CONCLUSIONS

EMP3 is an important prognostic indicator for selecting patients with upper urinary tract urothelial carcinoma for more intensive therapy. EMP3 is an innovative co-targeting candidate for designing ErbB2 based cancer therapy.

Integrative genomic and functional profiling of the pancreatic cancer genome

Background

Pancreatic cancer is a deadly disease with a five-year survival of less than 5%. A better understanding of the underlying biology may suggest novel therapeutic targets. Recent surveys of the pancreatic cancer genome have uncovered numerous new alterations; yet systematic functional characterization of candidate cancer genes has lagged behind. To address this challenge, here we have devised a highly-parallel RNA interference-based functional screen to evaluate many genomically-nominated candidate pancreatic cancer genes simultaneously.

Results

For 185 candidate pancreatic cancer genes, selected from recurrently altered genomic loci, we performed a pooled shRNA library screen of cell growth/viability across 10 different cell lines. Knockdown-associated effects on cell growth were assessed by enrichment or depletion of shRNA hairpins, by hybridization to barcode microarrays. A novel analytical approach (COrrelated Phenotypes for On-Target Effects; COPOTE) was used to discern probable on-target knockdown, based on identifying different shRNAs targeting the same gene and displaying concordant phenotypes across cell lines. Knockdown data were integrated with genomic architecture and gene-expression profiles, and selected findings validated using individual shRNAs and/or independent siRNAs. The pooled shRNA library design delivered reproducible data. In all, COPOTE analysis identified 52 probable on-target gene-knockdowns. Knockdown of known oncogenes (KRAS, MYC, SMURF1 and CCNE1) and a tumor suppressor (CDKN2A) showed the expected contrasting effects on cell growth. In addition, the screen corroborated purported roles of PLEKHG2 and MED29 as 19q13 amplicon drivers. Most notably, the analysis also revealed novel possible oncogenic functions of nucleoporin NUP153 (ostensibly by modulating TGFβ signaling) and Kruppel-like transcription factor KLF5 in pancreatic cancer.

Conclusions

By integrating physical and functional genomic data, we were able to simultaneously evaluate many candidate pancreatic cancer genes. Our findings uncover new facets of pancreatic cancer biology, with possible therapeutic implications. More broadly, our study provides a general strategy for the efficient characterization of candidate genes emerging from cancer genome studies.

Ovarian cancer cells, not normal cells, are damaged by Mirk/Dyrk1B kinase inhibition

Prior studies had shown that the Mirk/dyrk1B gene is amplified/upregulated in about 75% of ovarian cancers, that protein levels of this kinase are elevated in quiescent G0 cells and that Mirk maintains tumor cells in quiescence by initiating rapid degradation of cyclin D isoforms and by phosphorylation of a member of the DREAM complex. Depletion of Mirk/dyrk1B led to increased cyclin D levels, an elevated reactive oxygen species (ROS) content and loss of viability. However, many normal cells in vivo are quiescent, and therefore, targeting a kinase found in quiescent cells might be problematic. In our study, Mirk kinase activity was found to be higher in ovarian cancer cells than in normal cells. Pharmacological inhibition of Mirk/dyrk1B kinase increased cyclin D levels both in quiescent normal diploid cells and in quiescent CDKN2A-negative ovarian cancer cells, but led to more active CDK4/cyclin D complexes in quiescent ovarian cancer cells, allowing them to escape G0/G1 quiescence, enter cycle with high ROS levels and undergo apoptosis. The ROS scavenger N-acetyl cysteine reduced both the amount of cleaved poly(ADP-ribose) polymerase (PARP) and the extent of cancer cell loss. In contrast, normal cells were spared because of their expression of cyclin directed kinase (CDK) inhibitors that blocked unregulated cycling. Quiescent early passage normal ovarian epithelial cells and two strains of quiescent normal diploid fibroblasts remained viable after the inhibition of Mirk/dyrk1B kinase, and the few cells that left G0/G1 quiescence were accumulated in G2+M. Thus, inhibition of Mirk kinase targeted quiescent ovarian cancer cells.

Dysregulation of the basal RNA polymerase transcription apparatus in cancer

Mutations that directly affect transcription by RNA polymerases rank among the most central mediators of malignant transformation, but the frequency of new anticancer drugs that selectively target defective transcription apparatus entering the clinic has been limited. This is because targeting the large protein-protein and protein-DNA interfaces that control both generic and selective aspects of RNA polymerase transcription has proved extremely difficult. However, recent technological advances have led to a 'quantum leap' in our comprehension of the structure and function of the core RNA polymerase components, how they are dysregulated in a broad range of cancers and how they may be targeted for 'transcription therapy'.

Mirk/dyrk1B Kinase in Ovarian Cancer

Mirk/dyrk1B kinase is expressed in about 75% of resected human ovarian cancers and in most ovarian cancer cell lines with amplification in the OVCAR3 line. Mirk (minibrain-related kinase) is a member of the Minibrain/dyrk family of related serine/threonine kinases. Mirk maintains cells in a quiescent state by stabilizing the CDK inhibitor p27 and by inducing the breakdown of cyclin D isoforms. Mirk also stabilizes the DREAM complex, which maintains G0 quiescence by sequestering transcription factors needed to enter cycle. By entering a quiescent state, tumor cells can resist the nutrient deficiencies, hypoxic and acidic conditions within the tumor mass. Mirk maintains the viability of quiescent ovarian cancer cells by reducing intracellular levels of reactive oxygen species. CDKN2A-negative ovarian cancer cells treated with a Mirk kinase inhibitor escaped G0/G1 quiescence, entered cycle with high ROS levels and underwent apoptosis. The ROS scavenger N-acetyl cysteine reduced the extent of cancer cell loss. In contrast, the Mirk kinase inhibitor slightly reduced the fraction of G0 quiescent diploid epithelial cells and fibroblasts, and the majority of the cells pushed into cycle accumulated in G2 + M. Apoptotic sub-G0/G1 cells were not detected. Thus, normal cells were spared because of their expression of CDK inhibitors that blocked unregulated cycling and Mirk kinase inhibitor-treated normal diploid cells were about as viable as untreated controls.

The GCTM-5 epitope associated with the mucin-like glycoprotein FCGBP marks progenitor cells in tissues of endodermal origin

Monoclonal antibodies against cell surface markers are powerful tools in the study of tissue regeneration, repair, and neoplasia, but there is a paucity of specific reagents to identify stem and progenitor cells in tissues of endodermal origin. The epitope defined by the GCTM-5 monoclonal antibody is a putative marker of hepatic progenitors. We sought to analyze further the distribution of the GCTM-5 antigen in normal tissues and disease states and to characterize the antigen biochemically. The GCTM-5 epitope was specifically expressed on tissues derived from the definitive endoderm, in particular the fetal gut, liver, and pancreas. Antibody reactivity was detected in subpopulations of normal adult biliary and pancreatic duct cells, and GCTM-5-positive cells isolated from the nonparenchymal fraction of adult liver expressed markers of progenitor cells. The GCTM-5-positive cell populations in liver and pancreas expanded greatly in numbers in disease states such as biliary atresia, cirrhosis, and pancreatitis. Neoplasms arising in these tissues also expressed the GCTM-5 antigen, with pancreatic adenocarcinoma in particular showing strong and consistent reactivity. The GCTM-5 epitope was also strongly displayed on cells undergoing intestinal metaplasia in Barrett's esophagus, a precursor to esophageal carcinoma. Biochemical, mass spectrometry, and immunochemical studies revealed that the GCTM-5 epitope is associated with the mucin-like glycoprotein FCGBP. The GCTM-5 epitope on the mucin-like glycoprotein FCGBP is a cell surface marker for the study of normal differentiation lineages, regeneration, and disease progression in tissues of endodermal origin.

Clinical profiles and long-term outcomes of patients with pancreatic ductal adenocarcinoma and diabetes mellitus

BACKGROUND

Diabetes mellitus (DM) is considered to be a possible risk factor and/or a manifestation of pancreatic ductal adenocarcinoma (PDAC). This study is aimed at analysing the potential association of diabetes mellitus with the development and pathogenic degrees of PDAC and post-surgical survival of Chinese Han PDAC patients.

METHODS

A total of 1123 patients with PDAC were recruited and included 256 patients with diabetes mellitus within 2 years (new-onset) and 62 patients with diabetes mellitus ≥ 2 years (long-standing). Additional 466 patients with type 2 diabetes mellitus were included in this study. Their clinical characteristics and long-term outcomes were analysed.

RESULTS

In comparison with patients with type 2 diabetes mellitus alone, PDAC patients with new-onset diabetes mellitus had an older onset age of diabetes mellitus and lower body mass index (BMI). Among PDAC cases, patients with new-onset diabetes mellitus were associated with neural invasion, poor tumour differentiation and shorter post-surgical survival. However, more than half of these patients became euglycemic after surgical resection of tumours.

CONCLUSIONS

PDAC patients developed new-onset diabetes mellitus at an older age, and they had shorter post-surgical survival. The underlying mechanisms by which comorbid diabetes mellitus affect the clinical profiles and outcomes of PDAC patients deserve further researches.

Inactivation of mirk/dyrk1b kinase targets quiescent pancreatic cancer cells

A major problem in the treatment of cancer arises from quiescent cancer cells that are relatively insensitive to most chemotherapeutic drugs and radiation. Such residual cancer cells can cause tumor regrowth or recurrence when they reenter the cell cycle. Earlier studies showed that levels of the serine/theronine kinase Mirk/dyrk1B are elevated up to 10-fold in quiescent G(0) tumor cells. Mirk uses several mechanisms to block cell cycling, and Mirk increases expression of antioxidant genes that decrease reactive oxygen species (ROS) levels and increase quiescent cell viability. We now show that a novel small molecule Mirk kinase inhibitor blocked tumor cells from undergoing reversible arrest in a quiescent G(0) state and enabled some cells to exit quiescence. The inhibitor increased cycling in Panc1, AsPc1, and SW620 cells that expressed Mirk, but not in HCT116 cells that did not. Mirk kinase inhibition elevated ROS levels and DNA damage detected by increased phosphorylation of the histone protein H2AX and by S-phase checkpoints. The Mirk kinase inhibitor increased cleavage of the apoptotic proteins PARP and caspase 3, and increased tumor cell kill several-fold by gemcitabine and cisplatin. A phenocopy of these effects occurred following Mirk depletion, showing drug specificity. In previous studies Mirk knockout or depletion had no detectable effect on normal tissue, suggesting that the Mirk kinase inhibitor could have a selective effect on cancer cells expressing elevated levels of Mirk kinase.

Cholecystectomy and risk of pancreatic cancer: a meta-analysis of observational studies

OBJECTIVE

Data from epidemiological studies related to the association of cholecystectomy and pancreatic cancer (PaC) risk are inconsistent. We conducted a meta-analysis of observational studies to explore this relationship.

METHODS

We identified studies by a literature search of Medline (from 1 January 1966) and EMBASE (from 1 January 1974), through 30 June 2011, and by searching the reference lists of pertinent articles. Summary relative risks with their 95% confidence intervals were calculated with a random-effects model. Between-study heterogeneity was assessed using Cochran's Q statistic and the I (2).

RESULTS

A total of 18 studies (10 case-control studies, eight cohort studies) were included in this meta-analysis. Analysis of these 18 studies found that cholecystectomy was associated with a 23% excess risk of PaC (SRR = 1.23, 95% CI = 1.12-1.35), with moderate heterogeneity among these studies (p (heterogeneity) = 0.006, I (2) = 51.0%). Sub-grouped analyses revealed that the increased risk of PaC was independent of geographic location, gender, study design and confounders. There was no publication bias in the current meta-analysis.

CONCLUSIONS

The results of this meta-analysis suggest that individuals with a history of cholecystectomy may have an increased risk of pancreatic cancer.

Mediator and human disease

Since the identification of a metazoan counterpart to yeast Mediator nearly 15 years ago, a convergent body of biochemical and molecular genetic studies have confirmed their structural and functional relationship as an integrative hub through which regulatory information conveyed by signal activated transcription factors is transduced to RNA polymerase II. Nonetheless, metazoan Mediator complexes have been shaped during evolution by substantive diversification and expansion in both the number and sequence of their constituent subunits, with important implications for the development of multicellular organisms. The appearance of unique interaction surfaces within metazoan Mediator complexes for transcription factors of diverse species-specific origins extended the role of Mediator to include an essential function in coupling developmentally coded signals with precise gene expression output sufficient to specify cell fate and function. The biological significance of Mediator in human development, suggested by genetic studies in lower metazoans, is emphatically illustrated by an expanding list of human pathologies linked to genetic variation or aberrant expression of its individual subunits. Here, we review our current body of knowledge concerning associations between individual Mediator subunits and specific pathological disorders. When established, molecular etiologies underlying genotype-phenotype correlations are addressed, and we anticipate that future progress in this critical area will help identify therapeutic targets across a range of human pathologies.

Transient arrest in a quiescent state allows ovarian cancer cells to survive suboptimal growth conditions and is mediated by both Mirk/dyrk1b and p130/RB2

Some ovarian cancer cells in vivo are in a reversible quiescent state where they can contribute to cancer spread under favorable growth conditions. The serine/threonine kinase Mirk/dyrk1B was expressed in each of seven ovarian cancer cell lines and in 21 of 28 resected human ovarian cancers, and upregulated in 60% of the cancers. Some ovarian cancer cells were found in a G0 quiescent state, with the highest fraction in a line with an amplified Mirk gene. Suboptimal culture conditions increased the G0 fraction in SKOV3 and TOV21G, but not OVCAR4 cultures. Less than half as many OVCAR4 cells survived under suboptimal culture conditions as shown by total cell numbers, dye exclusion viability studies, and assay of cleaved apoptotic marker proteins. G0 arrest in TOV21G and SKOV3 cells led to increased levels of Mirk, the CDK inhibitor p27, p130/Rb2, and p130/Rb2 complexed with E2F4. The G0 arrest was transient, and cells exited G0 when fresh nutrients were supplied. Depletion of p130/Rb2 reduced the G0 fraction, increased cell sensitivity to serum-free culture and to cisplatin, and reduced Mirk levels. Mirk contributed to G0 arrest by destabilization of cyclin D1. In TOV21G cells, but not in normal diploid fibroblasts, Mirk depletion led to increased apoptosis and loss of viability. Because Mirk is expressed at low levels in most normal adult tissues, the elevated Mirk protein levels in ovarian cancers may present a novel therapeutic target, in particular for quiescent tumor cells which are difficult to eradicate by conventional therapies targeting dividing cells.

A neuronal transmembrane protein LRFN4 induces monocyte/macrophage migration via actin cytoskeleton reorganization

Leucine-rich repeat and fibronectin type III domain-containing (LRFN) family proteins are thought to be neuronal-specific proteins that play essential roles in neurite outgrowth and synapse formation. Here, we focused on expression and function of LRFN4, the fourth member of the LRFN family, in non-neural tissues. We found that LRFN4 was expressed in a wide variety of cancer and leukemia cell lines. We also found that expression of LRFN4 in the monocytic cell line THP-1 and in primary monocytes was upregulated following macrophage differentiation. Furthermore, we demonstrated that LRFN4 signaling regulated both the transendothelial migration of THP-1 cells and the elongation of THP-1 cells via actin cytoskeleton reorganization. Our data indicate that LRFN4 signaling plays an important role in the migration of monocytes/macrophages.

The role of mirk kinase in sarcomas

Targeting the tyrosine kinase KIT in gastrointestinal stromal tumors has led to improved treatment. Other kinases might serve as therapeutic targets in the more common forms of sarcoma. The kinase Mirk/dyrk1B is highly expressed in the vast majority of osteosarcomas and rhabdomyosarcomas and mediates their growth, as depletion of Mirk led to tumor cell apoptosis. Mirk is known to increase the expression of a series of antioxidant genes, which scavenge reactive oxygen species (ROS) within various tumor cells, mediating their survival. As a result, depleting Mirk led to increased levels of damaging ROS. Tumor cells depleted of Mirk were also sensitized to low levels of chemotherapeutic drugs that increase ROS levels. In contrast, Mirk expression is quite low in most normal cells, and Mirk depletion or embryonic knockout of Mirk did not detectably affect cell survival. Thus targeting Mirk for intervention in sarcomas might spare most normal tissues.

Diabetes mellitus and risk of pancreatic cancer: A meta-analysis of cohort studies

BACKGROUND

Diabetes mellitus (DM) is widely considered to be associated with risk of pancreatic cancer (PaC), however, whether DM is a cause or a consequence of PaC is still controversial. We examined this association by conducting a detailed meta-analysis of cohort studies.

METHODS

Studies were identified by searching Medline and Embase through November 30, 2010. Summary relative risks (RRs) with their corresponding 95% confidence intervals (CIs) were calculated using a random-effects model.

RESULTS

A total of thirty-five cohort studies were included in this meta-analysis. DM was associated with an increased risk of PaC (the summary RRs=1.94; 95% CI, 1.66-2.27), with significant evidence of heterogeneity among these studies (p<0.001, I²=93.6%). Subgroup analyses revealed that the increased risk of PaC was independent of geographic locations, sex, study design, alcohol consumption, body mass index (BMI) and smoking status. In addition, the relative risk of PaC was correlated negatively with the duration of DM, with the highest risk of PaC found among patients diagnosed within less than 1 year. There was no significant publication bias (p=0.136 for Egger's regression asymmetry test).

CONCLUSIONS

Findings from this meta-analysis strongly support that diabetes is associated with an increased risk of PaC in both males and females and that DM is both an early manifestation and an etiologic factor of pancreatic cancer.

MED29, a component of the mediator complex, possesses both oncogenic and tumor suppressive characteristics in pancreatic cancer

Mediator complex subunit 29 (MED29) is part of a large multiprotein coactivator complex that mediates regulatory signals from gene-specific activators to general transcription machinery in RNA polymerase II mediated transcription. We previously found that MED29 is amplified and overexpressed in pancreatic cancer and that MED29 silencing leads to decreased cell survival in PANC-1 pancreatic cancer cells with high MED29 expression. Here we further demonstrate decreased migration, invasion and colony formation in PANC-1 cells after MED29 silencing. Unexpectedly, lentiviral-based overexpression of MED29 led to decreased proliferation of NIH/3T3 cells as well as MIAPaCa-2 pancreatic cancer cells with low endogenous expression. More importantly, subcutaneous inoculation of the MED29-transduced pancreatic cancer cells into immuno-compromised mice resulted in dramatic tumor suppression. The mock-control mice developed large tumors, whereas the animals with MED29-xenografts showed both decreased tumor incidence and a major reduction in tumor size. Gene expression analysis in the MED29-transduced pancreatic cancer cells revealed differential expression of genes involved in control of cell cycle and cell division. The observed gene expression changes are expected to modulate the cell cycle in a way that leads to reduced cell growth, explaining the in vivo tumor suppressive phenotype. Taken together, these data implicate MED29 as an important regulator of key cellular functions in pancreatic cancer with both oncogenic and tumor suppressive characteristics. Such a dualistic role appears to be more common than previously thought and is likely to depend on the genetic background of the cancer cells and their surrounding environment.

Pancreatic cancer incidence and outcome in relation to ABO blood groups among Han Chinese patients: a case-control study

The aim of the current study was to determine the association between ABO blood group and the risk and progression of pancreatic ductal adenocarcinoma (PDAC) in the Han Chinese ethnic group. During the period of 2000-2009, 1,431 patients with PDAC and 1,449 age- and sex-matched controls were recruited in two university-affiliated hospitals. An unconditional multivariable logistic regression analysis was used to estimate adjusted odds ratios (ORs). The relationship between patient ABO blood group and clinicopathologic features was also analyzed. Compared with subjects having blood group O, a modestly higher risk was observed among cases with blood group A or AB with adjusted ORs (95% confidence interval) of 1.368 (1.127-1.661) and 1.391 (1.053-1.838), respectively. The TNM stages of tumors in patients with non-O blood groups (A, B or AB) were more highly advanced than in patients with blood group O (p < 0.001). Among patients who underwent a potentially curative operation, the median survival time of patients with blood group O was significantly longer than that of patients with non-O blood groups (16.0 months vs. 11.0 months, p = 0.001, log-rank test). This study shows evidence of an association between blood group type and risk for development and progression of PDAC. These findings merit further confirmation in a large population-based prospective study in patients of the Han Chinese ethnic group.

RNAi-based functional pharmacogenomics

Experimental alteration of gene expression is a powerful technique for functional characterization of disease genes. RNA interference (RNAi) is a naturally occurring mechanism of gene regulation, which is triggered by the introduction of double-stranded RNA into a cell. This phenomenon can be synthetically exploited to down-regulate expression of specific genes by transfecting mammalian cells with synthetic short interfering RNAs (siRNAs). These siRNAs can be designed to silence the expression of specific genes bearing a particular target sequence in high-throughput (HT) siRNA experimental systems and may potentially be presented as a therapeutic strategy for inhibiting transcriptional regulation of genes. This can constitute a strategy that can inhibit targets that are not tractable by small molecules such as chemical compounds. Large-scale experiments using low-dose drug exposure combined with siRNA also represent a promising discovery strategy for the purpose of identifying synergistic targets that facilitate synthetic lethal combination phenotypes. In light of such advantageous applications, siRNA technology has become an ideal research tool for studying gene function. In this chapter, we focus on the application of RNAi, with particular focus on HT siRNA phenotype profiling, to support cellular pharmacogenomics.

Screening technologies for target identification in pancreatic cancer

Pancreatic cancer exhibits an extraordinarily high level of resistance to almost any kind of systemic therapy evaluated in clinical trials so far. Therefore, the identification of novel therapeutic targets is urgently required. High-throughput screens have emerged as an important tool to identify putative targets for diagnosis and therapy in an unbiased manner. More than a decade ago, microarray technology was introduced to identify differentially expressed genes in pancreatic cancer as compared to normal pancreas, chronic pancreatitis and other cancer types located in close proximity to the pancreas. In addition, proteomic screens have facilitated the identification of differentially secreted proteins in body fluids of pancreatic cancer patients, serving as possible biomarkers. Recently, RNA interference-based loss-of-function screens have been used to identify functionally relevant genes, whose knock-down has impact on pancreatic cancer cell viability, thereby representing potential new targets for therapeutic intervention. This review summarizes recent results of transcriptional, proteomic and functional screens in pancreatic cancer and discusses potentials and limitations of the respective technologies as well as their impact on future therapeutic developments.

Galectin-4 functions as a tumor suppressor of human colorectal cancer

Development of colorectal cancer (CRC) involves a series of genetic alterations with altered expression of proteins and cell signaling pathways. Here, we identified that galectin-4 (gal-4), a marker of differentiation, was down-regulated in CRC. The goal of this work was to determine the function of gal-4 in CRC. Toward this goal, the human colon biopsies and tissue microarrays containing a gradient of pathology were analyzed for gal-4 expression by immunohistochemistry. Cell proliferation, migration, motility, forced expression, knockdown, cell cycle and apoptosis assays were used to characterize gal-4 function. Immunohistochemistry identified that gal-4 expression was significantly down-regulated in adenomas and was essentially absent in invasive carcinomas. Forced expression of gal-4 in gal-4 -ve cells induced cell cycle arrest and retarded cell migration and motility. Further, gal-4 sensitized the cells to camptothecin-induced apoptosis. Gal-4 knockdown resulted in increased cell proliferation, migration and motility. Gal-4 was found to be associated with Wnt signaling proteins. Finally, gal-4 expression led to down-regulation of Wnt signaling target genes. This study demonstrates that loss of gal-4 is a common and specific event in CRC. This study also shows that gal-4 exhibits tumor suppressive effects in CRC cells in vitro. Through its ability to interact with and down-regulate the functions of Wnt signaling pathway, gal-4 reveals a new dimension in the control of the Wnt signaling pathway. Thus, gal-4 may prove to be an important molecule in understanding the biology of CRC.

Relationships linking amplification level to gene over-expression in gliomas

BACKGROUND

Gene amplification is thought to promote over-expression of genes favouring tumour development. Because amplified regions are usually megabase-long, amplification often concerns numerous syntenic or non-syntenic genes, among which only a subset is over-expressed. The rationale for these differences remains poorly understood.

METHODOLOGY/PRINCIPAL FINDING

To address this question, we used quantitative RT-PCR to determine the expression level of a series of co-amplified genes in five xenografted and one fresh human gliomas. These gliomas were chosen because we have previously characterised in detail the genetic content of their amplicons. In all the cases, the amplified sequences lie on extra-chromosomal DNA molecules, as commonly observed in gliomas. We show here that genes transcribed in non-amplified gliomas are over-expressed when amplified, roughly in proportion to their copy number, while non-expressed genes remain inactive. When specific antibodies were available, we also compared protein expression in amplified and non-amplified tumours. We found that protein accumulation barely correlates with the level of mRNA expression in some of these tumours.

CONCLUSIONS/SIGNIFICANCE

Here we show that the tissue-specific pattern of gene expression is maintained upon amplification in gliomas. Our study relies on a single type of tumour and a limited number of cases. However, it strongly suggests that, even when amplified, genes that are normally silent in a given cell type play no role in tumour progression. The loose relationships between mRNA level and protein accumulation and/or activity indicate that translational or post-translational events play a key role in fine-tuning the final outcome of amplification in gliomas.

Galectin-1 is silenced by promoter hypermethylation and its re-expression induces apoptosis in human colorectal cancer cells

Galectin-1 (gal-1) is an important molecule secreted by many tumors, which induces apoptosis in activated T-cells and promotes tumor angiogenesis, both of which phenomena facilitate successful establishment of tumor in the body. However, little is known about the function of intracellular gal-1 or its transcriptional regulation in colorectal cancer (CRC). Here, we demonstrate that gal-1 expression is epigenetically regulated in CRC through promoter hypermethylation. Intracellular gal-1 induces cell cycle arrest and apoptosis in CRC cells with concomitant down-regulation of Wnt and NF-κB signaling pathways. Together, these data suggested that gal-1 silencing imparts CRC with the ability to proliferate and escape apoptosis.

Depleting Mirk Kinase Increases Cisplatin Toxicity in Ovarian Cancer Cells

Cisplatin-based regimens are the standard of care for epithelial carcinoma of the ovary. Since cisplatin is known to increase intracellular levels of toxic reactive oxygen species (ROS), an increase in cisplatin toxicity selectively in cancer cells could result from further increasing the cisplatin-elevated ROS levels by targeting antioxidant genes upregulated in ovarian cancers. The serine/threonine kinase Mirk/dyrk1B is a transcriptional co-activator which increased the expression of the antioxidant genes superoxide dismutase 2 and ferroxidase in ovarian cancer cells. As a result, depletion of Mirk increased cellular ROS levels in each of 4 ovarian cancer cell lines. Mirk depletion averaged only about 4 fold, yet combined with cisplatin treatment enabled low levels of drug to increase ROS to toxic levels in both SKOV3 and TOV21G ovarian cancer cells. Lowering ROS levels by treatment with N-acetyl cysteine limited cisplatin toxicity, resulting in higher cell numbers and decreased cleavage of the apoptotic proteins PARP and caspase 3. Mirk has also been shown to block cells in G1 by inducing proteolysis of cyclin D1. Mirk depletion increased cyclin D1 levels in 3 of 4 ovarian cancer cell lines, implying that some Mirk depleted cells could more readily enter cycle, potentially increasing their sensitivity to cisplatin. Since Mirk is upregulated in a large subset of human ovarian cancers, but is expressed at low levels in most normal tissues, and embryonic knockout of Mirk results in viable and fertile mice, targeting Mirk may sensitize ovarian cancers to lower levels of cisplatin, while sparing normal tissues.

The Kinase Mirk/dyrk1B: A Possible Therapeutic Target in Pancreatic Cancer

Pancreatic ductal adenocarcinomas are strongly resistant to chemotherapeutic drugs and radiation, underscoring the need for new therapeutic targets, particularly ones which target the numerous out of cycle cancer cells. Analysis of resected tumors for nuclear Ki67 antigen has shown that about 70% of pancreatic cancer cells are out of cycle, some post-mitotic. Other out of cycle cells are in a quiescent, reversible G0 state, resistant to drugs which target dividing cells, with some able to repopulate a tumor. The serine/threonine kinase Mirk/dyrk1B is a downstream effector of oncogenic K-ras, the most common mutation in this cancer. Mirk expression is elevated in quiescent pancreatic cancer cells and mediates their prolonged survival through increasing expression of a cohort of antioxidant genes. Mirk is expressed in about 90% of pancreatic cancers and is amplified in a subset. Mirk appears not to be an essential gene for normal cells from embryonic knockout studies in mice and RNA interference studies on cultured cells, but is upregulated in pancreatic tumor cells. These unusual characteristics suggest that Mirk may be a selective target for therapeutic intervention.

19q13 amplification is associated with high grade and stage in pancreatic cancer

Pancreatic cancer is a devastating disease with an extremely poor prognosis, and thus, there is a great need for better diagnostic and therapeutic tools. The 19q13 chromosomal locus is amplified in several cancer types, including pancreatic cancer, but the possible clinical significance of this aberration remains unclear. We used fluorescence in situ hybridization on tissue microarrays containing 357 primary pancreatic tumors, 151 metastases, and 24 local recurrences as well as 120 cancer cell lines from various tissues to establish the frequency of the 19q13 amplification and to find potential correlations to clinical parameters including patient survival. Copy number increases were found in 12.2% of the primary pancreatic tumors and 9.3% of the cell lines, including those derived from bladder, colorectal, ovarian, and thyroid carcinomas. Copy number changes were linked to high grade (P = 0.044) and stage (P = 0.025) tumors, and the average survival time of patients with 19q13 amplification was shorter than that of those without this aberration. Our findings revealed recurrent 19q13 amplification in pancreatic cancer and involvement of the same locus as in bladder, colorectal, ovarian, and thyroid carcinomas. More importantly, the 19q13 amplifications were associated with poor tumor phenotype and showed a trend toward shorter survival.