Epigenetic silencing of DUSP9 induces the proliferation of human gastric cancer by activating JNK signaling

Dual-Specificity Phosphatases in Regulation of Tumor-Associated Macrophage Activity

The regulation of protein kinases by dephosphorylation is a key mechanism that defines the activity of immune cells. A balanced process of the phosphorylation/dephosphorylation of key protein kinases by dual-specificity phosphatases is required for the realization of the antitumor immune response. The family of dual-specificity phosphatases is represented by several isoforms found in both resting and activated macrophages. The main substrate of dual-specificity phosphatases are three components of mitogen-activated kinase signaling cascades: the extracellular signal-regulated kinase ERK1/2, p38, and Janus kinase family. The results of the study of model tumor-associated macrophages supported the assumption of the crucial role of dual-specificity phosphatases in the formation and determination of the outcome of the immune response against tumor cells through the selective suppression of mitogen-activated kinase signaling cascades. Since mitogen-activated kinases mostly activate the production of pro-inflammatory mediators and the antitumor function of macrophages, the excess activity of dual-specificity phosphatases suppresses the ability of tumor-associated macrophages to activate the antitumor immune response. Nowadays, the fundamental research in tumor immunology is focused on the search for novel molecular targets to activate the antitumor immune response. However, to date, dual-specificity phosphatases received limited discussion as key targets of the immune system to activate the antitumor immune response. This review discusses the importance of dual-specificity phosphatases as key regulators of the tumor-associated macrophage function.

DUSP4 Silencing Enhances the Sensitivity of Breast Cancer Cells to Doxorubicin through the Activation of the JNK/c-Jun Signalling Pathway

Doxorubicin (Dox) has limited efficiency in breast cancer (BC) due to drug-acquired resistance. The epithelial–mesenchymal transition (EMT) plays a major role in the survival and drug resistance of cancer cells. It was suggested that the JNK pathway was implicated in the response to Dox by regulating EMT. DUSP4/or MKP-2 is a well-known regulator of the JNK pathway and was found to be highly expressed in BC. However, its functional significance is not yet fully understood. In the present study, the possible involvement of MKP-2 in Dox-induced EMT was investigated in breast cancer cells. Immunohistochemistry for tissues obtained from BC patients (n = 108) revealed 71.3% of tissues stained positively for MKP-2 while only 28.7% stained negatively. However, MKP-2 protein expression exhibited no significant relationship between BC prognostic factors, such as histological grade, histological type, hormonal status, and Ki-67 marker, its expression was significantly correlated with age 40 or below. In MDA-MB-231 cells, Dox-induced phosphorylation of JNK was sufficiently enhanced in MKP-2 silenced cells. This resulted in the attenuation of Dox-induced EMT, cell cycle arrest, and ultimately accelerated apoptosis. It was confirmed that the acquisition of Dox sensitivity by MKP-2 silencing largely depends on the stimulation of the JNK pathway. Indeed, results showed that overexpressing MKP-2 in non-tumorigenic MCF-12A cells dramatically inhibited Dox-induced JNK activation and, subsequently, cell death. The present study, to our knowledge, is the first to provide evidence for the potential role of MKP-2 in chemoresistance to Dox through modulating the JNK pathway and enhancing EMT.

miR-132-3p Modulates DUSP9-Dependent p38/JNK Signaling Pathways to Enhance Inflammation in the Amnion Leading to Labor

Labor is a process of inflammation and hormonal changes involving both fetal and maternal compartments. MicroRNA-132-3p (miR-132-3p) has been reported to be involved in the development of inflammation-related diseases. However, little is known about its potential role in labor onset. This study aimed to explore the mechanism of miR-132-3p in amnion for labor initiation. In the mouse amnion membranes, the expression of miR-132-3p was found to increase gradually during late gestation. In human amniotic epithelial cell line (WISH), upregulation of miR-132-3p was found to increase proinflammatory cytokines and cyclooxygenase 2 (COX2) as well as prostaglandin E2 (PGE2), which was suppressed by miR-132-3p inhibitor. Dual-specificity phosphatase 9 (DUSP9) was identified as a novel target gene of miR-132-3p, which could be negatively regulated by miR-132-3p. DUSP9 was present in the mouse amnion epithelial cells, with a decrease in its abundance at 18.5 days post coitum (dpc) relative to 15.5 dpc. Silencing DUSP9 was found to facilitate the expression of proinflammatory cytokines and COX2 as well as PGE2 secretion in WISH cells, which could be attenuated by p38 inhibitor SB203580 or JNK inhibitor SP600125. Additionally, intraperitoneal injection of pregnant mice with miR-132-3p agomir not only caused preterm birth, but also promoted the abundance of COX2 as well as phosphorylated JNK and p38 levels, and decreased DUSP9 level in mouse amnion membranes. Collectively, miR-132-3p might participate in inflammation and PGE2 release via targeting DUSP9-dependent p38 and JNK signaling pathways to cause preterm birth.

The Cardiac Glycoside Deslanoside Exerts Anticancer Activity in Prostate Cancer Cells by Modulating Multiple Signaling Pathways

Simple Summary

Prostate cancer is a leading cause of cancer-related deaths among men, and novel therapies for advanced PCa are urgently needed. Cardiac glycosides are a group of attractive candidates for anticancer repurposing, but deslanoside has not been tested for a potential anticancer effect so far. This study aims to test the anticancer effect of deslanoside in PCa and investigate the underlying mechanisms. Deslanoside effectively inhibited colony formation and tumor growth in multiple prostate cancer cell lines. Such an inhibitory effect involved both the cell cycle arrest at G2/M and the induction of apoptosis. Deslanoside altered the expression of many genes, which belonged to various cancer-associated cellular processes and signaling pathways. Altered expression levels for 15 deslanoside-modulated genes correlate with recurrence-free survival or overall survival in PCa patients, some of which have not been implicated in cancer before. Therefore, deslanoside exerts anticancer activity in PCa cells by modulating gene expression.

Abstract

Prostate cancer (PCa) is a leading cause of cancer-related deaths among men worldwide, and novel therapies for advanced PCa are urgently needed. Cardiac glycosides represent an attractive group of candidates for anticancer repurposing, but the cardiac glycoside deslanoside has not been tested for potential anticancer activity so far. We found that deslanoside effectively inhibited colony formation in vitro and tumor growth in nude mice of PCa cell lines 22Rv1, PC-3, and DU 145. Such an anticancer activity was mediated by both the cell cycle arrest at G2/M and the induction of apoptosis, as demonstrated by different functional assays and the expression status of regulatory proteins of cell cycle and apoptosis in cultured cells. Moreover, deslanoside suppressed the invasion and migration of PCa cell lines. Genome-wide expression profiling and bioinformatic analyses revealed that 130 genes were either upregulated or downregulated by deslanoside in both 22Rv1 and PC-3 cell lines. These genes enriched multiple cellular processes, such as response to steroid hormones, regulation of lipid metabolism, epithelial cell proliferation and its regulation, and negative regulation of cell migration. They also enriched multiple signaling pathways, such as necroptosis, MAPK, NOD-like receptor, and focal adhesion. Survival analyses of the 130 genes in the TCGA PCa database revealed that 10 of the deslanoside-downregulated genes (ITG2B, CNIH2, FBF1, PABPC1L, MMP11, DUSP9, TMEM121, SOX18, CMPK2, and MAMDC4) inversely correlated, while one deslanoside-upregulated gene (RASD1) positively correlated, with disease-free survival in PCa patients. In addition, one deslanoside-downregulated gene (ENG) inversely correlated, while three upregulated genes (JUN, MXD1, and AQP3) positively correlated with overall survival in PCa patients. Some of the 15 genes have not been implicated in cancer before. These findings provide another candidate for repurposing cardiac glycosides for anticancer drugs. They also suggest that a diverse range of molecular events underlie deslanoside’s anticancer activity in PCa cells.

DUSP9, a Dual-Specificity Phosphatase with a Key Role in Cell Biology and Human Diseases

Mitogen-activated protein kinases (MAPKs) are essential for proper cell functioning as they regulate many molecular effectors. Careful regulation of MAPKs is therefore required to avoid MAPK pathway dysfunctions and pathologies. The mammalian genome encodes about 200 phosphatases, many of which dephosphorylate the MAPKs and bring them back to an inactive state. In this review, we focus on the normal and pathological functions of dual-specificity phosphatase 9 (DUSP9)/MAP kinase phosphatases-4 (MKP-4). This cytoplasmic phosphatase, which belongs to the threonine/tyrosine dual-specific phosphatase family and was first described in 1997, is known to dephosphorylate ERK1/2, p38, JNK and ASK1, and thereby to control various MAPK pathway cascades. As a consequence, DUSP9 plays a major role in human pathologies and more specifically in cardiac dysfunction, liver metabolic syndromes, diabetes, obesity and cancer including drug response and cell stemness. Here, we recapitulate the mechanism of action of DUSP9 in the cell, its levels of regulation and its roles in the most frequent human diseases, and discuss its potential as a therapeutic target.

Dual-Specificity Phosphatase 9 Regulates Cellular Proliferation and Predicts Recurrence After Surgery in Hepatocellular Carcinoma

Hepatocellular carcinoma (CC) is a common and deadly cancer with complex molecular pathogenesis. Little is known about dual-specificity phosphatases (DUSPs) in HCC. We investigated DUSP9 expression in human HCC, associations between DUSP9 and patient outcomes, and effects of altered DUSP9 expression on HCC biology. We studied public data sets as well as 196 patients at our institution who had HCC resections. Quantitative real-time reverse transcription polymerase chain reaction and western blot demonstrated that DUSP9 expression was increased >10-fold in HCC compared to adjacent liver and healthy controls (P = 0.005). Kaplan-Meier and multivariable regression analyses revealed that higher DUSP9 expression was associated with shorter disease-free survival (high DUSP9, 1.6; 95% confidence interval, 0.9-2.3 vs. low DUSP9, 3.4; 95% confidence interval, 1.8-5.0 years; P = 0.04) and increased risk of recurrence (hazard ratio 1.55; 95% confidence interval, 1.01-2.67; P = 0.05) after resection. DUSP9 complementary DNA (cDNA) was cloned using rapid amplification of cDNA ends, revealing two DUSP9 isoforms in human HCC cells. Studies of transcriptional regulation using promoter-luciferase reporter constructs suggested that DUSP9 transcription is regulated by E26 transformation-specific transcription factors. Proliferation of hepatic cells in vitro was enhanced by lentiviral-mediated overexpression of DUSP9. In contrast, DUSP9 knockout HCC cells generated using clustered regularly interspaced short palindromic repeats (CRISPR) demonstrated decreased HCC proliferation and doxorubicin resistance in vitro and impaired xenograft growth in vivo. RNA sequencing, gene set enrichment, and network/pathway analysis revealed that DUSP9 knockout is associated with activation of protein kinase activity and apoptosis. Conclusion: DUSP9 regulates cell proliferation and predicts recurrence after surgery in HCC. DUSP9 may represent a novel prognostic candidate and therapeutic target. Additional studies are warranted to further explore the role and regulation of DUSP9 in HCC.

Dual-specificity Phosphatase 9 protects against Cardiac Hypertrophy by targeting ASK1

The functions of dual-specificity phosphatase 9 (DUSP9) in hepatic steatosis and metabolic disturbance during nonalcoholic fatty liver disease were discussed in our prior study. However, its roles in the pathophysiology of pressure overload-induced cardiac hypertrophy remain to be illustrated. This study attempted to uncover the potential contributions and underpinning mechanisms of DUSP9 in cardiac hypertrophy. Utilizing the gain-and-loss-of-functional approaches of DUSP9 the cardiac phenotypes arising from the pathological, echocardiographic, and molecular analysis were quantified. The results showed increased levels of DUSP9 in hypertrophic mice heart and angiotensin II treated cardiomyocytes. In accordance with the results of cellular hypertrophy in response to angiotensin II, cardiac hypertrophy exaggeration, fibrosis, and malfunction triggered by pressure overload was evident in the case of cardiac-specific conditional knockout of DUSP9. In contrast, transgenic mice hearts with DUSP9 overexpression portrayed restoration of the hypertrophic phenotypes. Further explorations of molecular mechanisms indicated the direct interaction of DUSP9 with ASK1, which further repressed p38 and JNK signaling pathways. Moreover, blocking ASK1 with ASK1-specific inhibitor compensated the pro-hypertrophic effects induced by DUSP9 deficiency in cardiomyocytes. The main findings of this study suggest the potential of DUSP9 in alleviating cardiac hypertrophy at least partially by repressing ASK1, thereby looks promising as a prospective target against cardiac hypertrophy.

The emerging roles of dual-specificity phosphatases and their specific characteristics in human cancer

Reversible phosphorylation of proteins, controlled by kinases and phosphatases, is involved in various cellular processes. Dual-specificity phosphatases (DUSPs) can dephosphorylate phosphorylated serine, threonine and tyrosine residues. This family consists of 61 members, 44 of which have been identified in human, and these 44 members are classified into six subgroups, the phosphatase and tensin homolog (PTEN) protein phosphatases (PTENs), mitogen-activated protein kinase phosphatases (MKPs), atypical DUSPs, cell division cycle 14 (CDC14) phosphatases (CDC14s), slingshot protein phosphatases (SSHs), and phosphatases of the regenerating liver (PRLs). Growing evidence has revealed dysregulation of DUSPs as one of the common phenomenons and highlighted their key roles in human cancers. Furthermore, their differential expression may be a potential biomarker for tumor prognosis. Despite this, there are still many unstudied members of DUSPs need to further explore their precise roles and mechanism in cancers. Most importantly, the systematic review is very limited on the functional/mechanistic characteristics and clinical application of DUSPs at present. In this review, the structures, functions and underlying mechanisms of DUSPs are systematically reviewed, and the molecular and functional characteristics of DUSPs in different tumor types according to the current researches are summarized. In addition, the potential roles of the unstudied members and the possible different mechanisms of DUSPs in cancer are discussed and classified based on homology alignment and structural domain analyses. Moreover, the specific characteristics of their expression and prognosis are further determined in more than 30 types of human cancers by using the online databases. Finally, their potential application in precise diagnosis, prognosis and treatment of different types of cancers, and the main possible problems for the clinical application at present are prospected.

A comprehensive review on the role of protein tyrosine phosphatases in gastric cancer development and progression

The main post-translational reversible modulation of proteins is phosphorylation and dephosphorylation, catalyzed by protein kinases (PKs) and protein phosphatases (PPs) which is crucial for homeostasis. Imbalance in this crosstalk can be related to diseases, including cancer. Plenty of evidence indicates that protein tyrosine phosphatases (PTPs) can act as tumor suppressors and tumor promoters. In gastric cancer (GC), there is a lack of understanding of the molecular aspects behind the tumoral onset and progression. Here we describe several members of the PTP family related to gastric carcinogenesis. We discuss the associated molecular mechanisms which support the down or up modulation of different PTPs. We emphasize the Helicobacter pylori (H. pylori) virulence which is in part associated with the activation of PTP receptors. We also explore the involvement of intracellular redox state in response to H. pylori infection. In addition, some PTP members are under influence by genetic mutations, epigenetics mechanisms, and miRNA modulation. The understanding of multiple aspects of PTPs in GC may provide new targets and perspectives on drug development.

Downregulation of DUSP9 Promotes Tumor Progression and Contributes to Poor Prognosis in Human Colorectal Cancer

Background

Dual-specificity phosphatase 9 (DUSP9) belongs to the dual-specificity protein phosphatase subfamily. Recently, increasing attention has been paid on the role of DUSP9 in a variety of cancers. However, its functional role in tumor development is still unclear, especially in colorectal cancer (CRC).

Methods

The functional role of DUSP9 in inhibiting the progression of CRC was verified using colony formation assay, wound healing assay, nude mice xenograft model, etc. RNA-seq was performed to assess the gene expression profiling in SW480 cells with DUSP9 stable knockdown and shControl cells. Bisulfite sequencing (BSE) was performed to reveal the methylation status of CpG island in the promoter of DUSP9.

Results

DUSP9 was significantly downregulated in tumor tissues compared with peritumor tissues. Mechanistically, the high methylation status of CpG island in the promoter of DUSP9 may lead to the downregulation of DUSP9 in CRC. Clinically, low DUSP9 expression in CRC was closely associated with depth of invasion, metastasis (TNM) stage, and poor survival, indicating that DUSP9 may be involved in the progression of CRC. Functional study revealed that DUSP9 inhibited proliferation, migration, invasion, and epithelial–mesenchymal transition of CRC cells both in vitro and in vivo. Transcriptome profiling studies revealed that Erk signaling was involved in the tumor progression mediated by DUSP9 silencing, which is confirmed by cell experiments and clinical tissue sample staining analysis.

Conclusion

Our findings demonstrate that DUSP9 plays a critical role in the progression of CRC, and therapeutic intervention to increase the expression or activity of DUSP9 may be a potential target for CRC treatment in the future.

DUSP9 Suppresses Proliferation and Migration of Clear Cell Renal Cell Carcinoma via the mTOR Pathway

Background

Clear cell renal cell carcinoma (ccRCC) is one of the most common urologic tumors. However, the carcinogenic mechanism of ccRCC remains unclear. This study aimed to investigate the effects of dual specificity phosphatase 9 (DUSP9) in ccRCC.

Methods

Cell proliferation and migration abilities were detected by Cell Counting kit-8, wound-healing (scratch) assay and transwell assay. The expression of mRNA in ccRCC was measured by qPCR. Western blot and immunohistochemical staining were used for protein expression. In addition, nude mouse xenograft experiment establishes an in vivo model to detect the inhibitory effect of DUSP9 on tumor proliferation.

Results

DUSP9 was significantly down-regulated in both ccRCC cell lines and ccRCC tissues compared to that in non-cancer cell lines and normal tissues. Besides, DUSP9 suppressed proliferation and migration of ccRCC cell lines in vitro. Importantly, the inhibition of tumor growth by DUSP9 was confirmed by xenograft tumor studies. And DUSP9 could inhibit both phosphorylation of mTOR and expression of its pathway-associated proteins Sox2, c-Myc, and HIF-1α, which are involved in cell proliferation and migration.

Conclusion

Taken together, our results uncovered DUSP9 as a tumor suppressor in ccRCC, acting by regulating cell proliferation and migration via the mTOR pathway.

Protein tyrosine phosphatases: promising targets in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer. It is the fourth leading cause of cancer-related death and is associated with a very poor prognosis. KRAS driver mutations occur in approximately 95% of PDAC cases and cause the activation of several signaling pathways such as mitogen-activated protein kinase (MAPK) pathways. Regulation of these signaling pathways is orchestrated by feedback loops mediated by the balance between protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs), leading to activation or inhibition of its downstream targets. The human PTPome comprises 125 members, and these proteins are classified into three distinct families according to their structure. Since PTP activity description, it has become clear that they have both inhibitory and stimulatory effects on cancer-associated signaling processes and that deregulation of PTP function is closely associated with tumorigenesis. Several PTPs have displayed either tumor suppressor or oncogenic characteristics during the development and progression of PDAC. In this sense, PTPs have been presented as promising candidates for the treatment of human pancreatic cancer, and many PTP inhibitors have been developed since these proteins were first associated with cancer. Nevertheless, some challenges persist regarding the development of effective and safe methods to target these molecules and deliver these drugs. In this review, we discuss the role of PTPs in tumorigenesis as tumor suppressor and oncogenic proteins. We have focused on the differential expression of these proteins in PDAC, as well as their clinical implications and possible targeting for pharmacological inhibition in cancer therapy.

Genome-Wide DNA Methylome and Transcriptome Analysis of Porcine Intestinal Epithelial Cells upon Deoxynivalenol Exposure

Deoxynivalenol (DON) is a type of mycotoxin that is disruptive to intestinal and immune systems. To better understand the molecular effects of DON exposure, we performed genome-wide comparisons of DNA methylation and gene expression from porcine intestinal epithelial cell IPEC-J2 upon DON exposure using reduced representation bisulfite sequencing and RNA-seq technologies. We characterized the methylation pattern changes and found 3030 differentially methylated regions. Moreover, 3226 genes showing differential expression were enriched in pathways of protein and nucleic acid synthesis and ribosome biogenesis. Integrative analysis identified 29 genes showing inverse correlations between promoter methylation and expression. Altered DNA methylation and expression of various genes suggested their roles and potential functional interactions upon DON exposure. Our data provided new insights into epigenetic and transcriptomic alterations of intestinal epithelial cells upon DON exposure and may advance the identification of biomarkers and drug targets for predicting and controlling the toxic effects of this common mycotoxin.

MKP-4 suppresses hepatocarcinogenesis by targeting ERK1/2 pathway

Background

Mitogen-activated protein kinase phosphatases-4 (MKP-4) is reported to exert a prognostic merit in hepatocarcinogenesis. However, the underlying molecular mechanisms have not been clearly defined.

Methods

Immunoprecipitation-mass spectrometry (IP-MS) approach was used to identify interactive proteins with MKP-4. Western blot and immunohistochemistry were employed to detect proteins in HCC tissues. Cell counting kit-8, colony formation, Edu incorporation and sphere formation assays were performed to investigate functions of MKP-4/ERK1/2 interaction. Tumor xenografts in nude mice were used to determine effects in vivo.

Results

Extracellular signal-regulated kinase 1 and 2 (ERK1/2) were identified as binding partners of MKP-4. Knockdown of MKP-4 increased cell proliferation and cancer stem cell (CSC) traits while upregulation of MKP-4 or pre-incubation with ERK1/2 inhibition reversed these effects. Mechanistically MKP-4 negatively regulated phosphorylation of ERK1/2 and reduced expressions of CyclinD1 and c-Myc. Both xenograft tumor models and clinical analysis of HCC patients indicated that lower expression of MKP-4 and higher expressions of ERK1/2 were associated with worse prognosis.

Conclusions

MKP-4-mediated dephosphorylation of ERK1/2 might serve as a novel tumor-suppressive mechanism and provide a potential therapy for HCC.

Aberrant expression of JNK-associated leucine-zipper protein, JLP, promotes accelerated growth of ovarian cancer

Ovarian cancer is the most fatal gynecologic cancer with poor prognosis. Etiological factors underlying ovarian cancer genesis and progression are poorly understood. Previously, we have shown that JNK-associated Leucine zipper Protein (JLP), promotes oncogenic signaling. Investigating the role of JLP in ovarian cancer, our present study indicates that JLP is overexpressed in ovarian cancer tissue and ovarian cancer cells. Transient overexpression of JLP promotes proliferation and invasive migration of ovarian cancer cells. In addition, ectopic expression of JLP confers long-term survival and clonogenic potential to normal fallopian tube-derived epithelial cells. Coimmunoprecipitation and colocalization analyses demonstrate the in vivo interaction of JLP and JNK, which is stimulated by lysophosphatidic acid (LPA), an oncogenic lipid growth factor in ovarian cancer. We also show that LPA stimulates the translocation of JLP-JNK complex to the perinuclear region of SKOV3-ip cells. JLP-knockdown using shRNA abrogates LPA-stimulated activation of JNK as well as LPA-stimulated proliferation and invasive migration of SKOV3-ip cells. Studies using ovarian cancer xenograft mouse model indicate that the mice bearing JLP-silenced xenografts exhibits reduced tumor volume. Analysis of the xenograft tumor tissues indicate a reduction in the levels of JLP, JNK, phosphorylated-JNK, c-Jun and phosphorylated-c-Jun in JLP-silenced xenografts, thereby correlating the attenuated JLP-JNK signaling node with suppressed tumor growth. Thus, our results identify a critical role for JLP-signaling axis in ovarian cancer and provide evidence that targeting this signaling node could provide a new avenue for therapy.

Tumor suppressive protein phosphatases in human cancer: Emerging targets for therapeutic intervention and tumor stratification

Aberrant protein phosphorylation is one of the hallmarks of cancer cells, and in many cases a prerequisite to sustain tumor development and progression. Like protein kinases, protein phosphatases are key regulators of cell signaling. However, their contribution to aberrant signaling in cancer cells is overall less well appreciated, and therefore, their clinical potential remains largely unexploited. In this review, we provide an overview of tumor suppressive protein phosphatases in human cancer. Along their mechanisms of inactivation in defined cancer contexts, we give an overview of their functional roles in diverse signaling pathways that contribute to their tumor suppressive abilities. Finally, we discuss their emerging roles as predictive or prognostic markers, their potential as synthetic lethality targets, and the current feasibility of their reactivation with pharmacologic compounds as promising new cancer therapies. We conclude that their inclusion in clinical practice has obvious potential to significantly improve therapeutic outcome in various ways, and should now definitely be pushed forward.

IRAK1, a Target of miR-146b, Reduces Cell Aggressiveness of Human Papillary Thyroid Carcinoma

CONTEXT

MicroRNA (miR)-146b is overexpressed in papillary thyroid carcinoma (PTC) and is associated with extrathyroidal invasion, advanced tumor stage, and poor prognosis. However, the underlying mechanism of miR-146b in relation to its oncogenic behavior in PTC and its putative targets remain unknown.

OBJECTIVE

The purpose was to investigate IL-1 receptor-associated kinase 1 (IRAK1) as the potential miR-146b target gene and its involvement in PTC.

DESIGN

We used genome-wide microarray, computational analysis, and 3' UTR reporter gene assays to identify IRAK1 as a miR-146b target gene. In vitro gain/loss-of-function experiments were further performed to determine the effects of IRAK1 on proliferation, colony formation, and wound-healing in PTC cancer cell lines. Expression levels of miR-146b and IRAK1 of 50 cases of PTC and its adjacent normal thyroid specimens were assessed via qRT-PCR.

RESULTS

Microarray expression profile revealed that the mRNA level of IRAK1 gene was down-regulated by miR-146b. The 3' UTR of IRAK1 mRNA was found to be a molecular target of miR-146b posttranscriptional repression in BCPAP cells by reporter gene assays. MiR-146b promoted the migration and proliferation of PTC cells by down-regulating IRAK1 expression, whereas restoration of IRAK1 expression reversed this effect. In addition, the expression of IRAK1 mRNA was significantly lower in PTC clinical tissue samples than normal adjacent thyroid specimens and showed a strong inverse correlation with the expression of miR-146b in PTC specimens.

CONCLUSION

Our results demonstrated that IRAK1 is a direct target of miR-146b and has functional roles to inhibit various aggressive PTC cell activities. In conjunction with current therapeutic regimens, targeting the miR-146b-IRAK1 axis may provide a potential approach for PTC management.

Anticancer effects of clinically acceptable colchicine concentrations on human gastric cancer cell lines

Colchicine is a very cheap microtubule destabilizer. Because microtubules are an ideal target for anticancer drugs, the purpose of this study was to investigate whether clinically acceptable colchicine concentrations have anticancer effects on gastric cancer cells, and its possible anticancer mechanisms. Two human gastric cancer cell lines (i.e., AGS and NCI-N87) were investigated by proliferative assay, microarray, quantitative reverse transcriptase-polymerase chain reaction, and a nude mice study using clinically acceptable colchicine concentrations (2 ng/mL and 6 ng/mL for in vitro tests and 0.07 mg colchicine/kg/d for in vivo tests). Our results showed that colchicine had the same inhibitory effects on the proliferation of both cell lines. The antiproliferative effects of colchicine on both cell lines were achieved only at the concentration of 6 ng/mL (p < 0.0001). In both cell lines, 18 genes were consistently upregulated and 10 genes were consistently downregulated by 6 ng/mL colchicine, compared with 2 ng/mL colchicine. Among these genes, only the upregulated DUSP1 gene may contribute to the antiproliferative effects of colchicine on gastric cancer cells. The nude mice (BALB/c-nu) experiment showed that colchicine-treated mice after 14 days of treatment had lower increased tumor volume ratios (p = 0.0199) and tumor growth rates (p = 0.024) than the control mice. In conclusion, colchicine has potential for the palliative treatment of gastric cancer. However, the anticancer effects are achieved only at high clinically acceptable colchicine concentrations. Monitoring the colchicine plasma concentration is mandatory if this drug is applied for the palliative treatment of gastric cancer.