TRIM44 promotes cell proliferation and migration by inhibiting FRK in renal cell carcinoma

TRIM44 has oncogenic roles in various cancers. However, TRIM44 expression and its function in renal cell carcinoma (RCC) are still unknown. Here in this study, we investigated the clinical significance of TRIM44 and its biological function in RCC. TRIM44 overexpression was significantly associated with clinical M stage, histologic type (clear cell) and presence of lymphatic invasion (P = .047, P = .005, and P = .028, respectively). Moreover, TRIM44 overexpression was significantly associated with poor prognosis in terms of cancer‐specific survival (P = .019). Gain‐of‐function and loss‐of‐function studies using TRIM44 and siTRIM44 transfection showed that TRIM44 promotes cell proliferation and cell migration in two RCC cell lines, Caki1 and 769P. To further investigate the role of TRIM44 in RCC, we performed integrated microarray analysis in Caki1 and 769P cells and explored the data in the Oncomine database. Interestingly, FRK was identified as a promising candidate target gene of TRIM44, which was downregulated in RCC compared with normal renal tissues. We found that cell proliferation was inhibited by TRIM44 knockdown and then recovered by siFRK treatment. Taken together, the present study revealed the association between high expression of TRIM44 and poor prognosis in RCC patients and that TRIM44 promotes cell proliferation by regulating FRK.     

A novel prognostic factor TRIM44 promotes cell proliferation and migration,and inhibits apoptosis in testicular germ cell tumor

Tripartite motif 44 (TRIM44) is one of the TRIM family proteins that are involved in ubiquitination and degradation of target proteins by modulating E3 ubiquitin ligases. TRIM44 overexpression has been observed in various cancers. However, its association with testicular germ cell tumor (TGCT) is unknown. We aimed to investigate the clinical significance of TRIM44 and its function in TGCT. High expression of TRIM44 was significantly associated with α feto‐protein levels, clinical stage, nonseminomatous germ cell tumor (NSGCT), and cancer‐specific survival (P = 0.0009, P = 0.0035, P = 0.0004, and P = 0.0140, respectively). Multivariate analysis showed that positive TRIM44 IR was an independent predictor of cancer‐specific mortality (P = 0.046). Gain‐of‐function study revealed that overexpression of TRIM44 promoted cell proliferation and migration of NTERA2 and NEC8 cells. Knockdown of TRIM44 using siRNA promoted apoptosis and repressed cell proliferation and migration in these cells. Microarray analysis of NTERA2 cells revealed that tumor suppressor genes such as CADM1, CDK19, and PRKACB were upregulated in TRIM44‐knockdown cells compared to control cells. In contrast, oncogenic genes including C3AR1, ST3GAL5, and NT5E were downregulated in those cells. These results suggest that high expression of TRIM44 is associated with poor prognosis and that TRIM44 plays significant role in cell proliferation, migration, and anti‐apoptosis in TGCT.     

High expression of TRIM44 is associated with enhanced cell proliferation,migration, invasion,and resistance to doxorubicin in hepatocellular carcinoma

Dysregulation of TRIM44 has been reported to be involved in tumorigenesis, but its role in hepatocellular carcinoma (HCC) remains unclear. In the present study, we investigated the clinicopathological and biological significance of TRIM44 in HCC. We found that TRIM44 mRNA and protein expression was upregulated in HCC compared with matched normal tissues. Intriguingly, we also found that TRIM44 expression was significantly correlated with tumor size (P < 0.001), vascular invasion (P < 0.001), intrahepatic metastasis (P < 0.001), distant metastasis (P < 0.001), and Ki-67 expression (P < 0.001). Kaplan-Meier analysis showed that high TRIM44 staining was significantly correlated with shorter overall survival (P < 0.001). TRIM44 was an independent predictor of overall survival in patients with HCC. Furthermore, we found that ectopic expression of TRIM44 could promote cell proliferation via accelerating the G1/S-phase transition in HCC. Moreover, overexpression of TRIM44 could enhance the invasive and migratory capacity of HCC cells. Meanwhile, we found that high expression of TRIM44 could enhance resistance of HCC cells to doxorubicin via accelerating NF-κB activation. In conclusion, our results suggest that TRIM44 may be a novel prognostic indicator and potential therapeutic target of HCC.

     

Metastasis‐associated in colon cancer‐1 upregulation predicts a poor prognosis of gastric cancer,and promotes tumor cell proliferation and invasion

Metastasis‐associated in colon cancer‐1 (MACC1) is a newly identified oncogene, and little is known about its role in gastric cancer (GC). Our study was performed to investigate whether MACC1 influences the prognosis of GC patients and to explore the potential mechanisms involved. MACC1 expression was verified to be higher in GC tissues than in adjacent nontumorous tissues by Western blotting. A retrospective analysis of 361 GC patients (Stages I–IV) revealed that higher MACC1 expression was associated with more advanced disease, more frequent postoperative recurrence, more metastases and a higher mortality rate. The disease‐free survival of Stage I–III patients and overall survival of Stage‐IV patients were significantly worse when their tumors showed high MACC1 expression. To investigate the underlying mechanisms, MACC1 overexpression and downregulation were established in two GC cell lines (BGC‐823 and MKN‐28 cells). MACC1 overexpression significantly accelerated tumor growth and facilitated metastasis in athymic mice. MACC1 also promoted the proliferation, migration and invasion of both GC cell lines. Moreover, gastric MACC1 mRNA expression levels were significantly correlated with markers of the epithelial‐to‐mesenchymal transition (EMT) in patients with GC. MACC1 overexpression upregulated mesenchymal–epithelial transition factor and induced changes to markers of EMT, whereas silencing of MACC1 reversed all these changes. These findings provide some novel insights into the role of MACC1, a gene that contributes to a poor prognosis of GC by promoting tumor cell proliferation and invasion as well as the EMT.     

Tripartite motif-containing 3 (TRIM3) inhibits tumor growth and metastasis of liver cancer

Background:Reduced expression of tripartite motif-containing 3 (TRIM3) has been reported to be involved in the pathogenesis of human glioblastoma.In our previous research,we found that TRIM3 expression was markedly reduced in human primary hepatocellular carcinoma (HCC) tissues and that low TRIM3 expression was associated with short survival of HCC patients.However,the role of TRIM3 in liver cancer remains unknown.This study aimed to investigate the function of TRIM3 in liver cancer cells.Methods:The protein levels of TRIM3 in five liver cancer cell lines (SK-Hep1,Hep3B,Huh7,HepG2,Bel-7402) and one normal liver cell line (L02) were detected with Western blotting.HepG2 and Bel-7402 cells with IowTRIM3 expression were infected with recombinant lentiviruses overexpressing TRIM3 (LV-TRIM3),whereas Huh7 and Hep3B cells with high TRIM3 expression were transfected with TRIM3-targeted small interfering RNA (siTRIM3).The functions of TRIM3 in the proliferation,colony formation,cell cycle,migration,invasion,and apoptosis of the above cell lines were examined.The effect of TRIM3 on tumor growth and metastases in nude mice was also investigated.Results:TRIM3 was overexpressed in HepG2 and Bel-7402 cells with LV-TRIM3 infection,which further reduced proliferation,colony formation,migration,and invasion of both cell lines.Cell cycle analysis showed thatTRIM3 overexpression induced G0/G1 phase arrest in HepG2 and Bel-7402 cells.Moreover,apoptosis was not increased in HepG2 or Bel-7402 cells overexpressing TRIM3.Contrarily,silencing TRIM3 expression in Huh7 and Hep3B cells by siTRIM3 led to significantly decreased percentages of both cells in the G0/G1 phase and promoted cell proliferation,colony formation,migration,and invasion.In vivo experiment results confirmed thatTRIM3 overexpression suppressed tumor growth and metastasis.Conclusions:TRIM3 plays a tumor-suppressing role in the regulation of liver cancer development by reducing cell proliferation through cell cycle arrest at the G0/G1 phase.     

High expression of KIBRA in low atypical protein kinase C‐expressing gastric cancer correlates with lymphatic invasion and poor prognosis

Overexpression of atypical protein kinase Cλ/ι (aPKCλ/ι), a regulator of cell polarity, is frequently associated with the poor prognoses of several cancers, including gastric cancer. Recent studies revealed a molecular link between aPKC and KIBRA, an upstream regulator of tumor suppressor Hippo pathway that regulates cell proliferation and apoptosis. Further, KIBRA directly inhibits the kinase activity of aPKC to regulate epithelial cell polarity. These observations suggest that the KIBRA‐aPKC connection plays a role in cancer progression; however, clinical significance of the correlation between these factors remains unclear. Here we examined the correlation between KIBRA/aPKCλ/ι expression, as detected by immunohistochemistry, and clinicopathological outcomes in 164 gastric cancer patients using Fisher's exact test and Kaplan–Meier log‐rank test. We found an intimate correlation between the expression level of KIBRA and aPKCλ/ι (P = 0.012). Furthermore, high expression of KIBRA is correlated with lymphatic (P = 0.046) and venous invasion (P = 0.039). The expression level of KIBRA by itself did not correlate with the prognosis; however, high expression of KIBRA in low aPKCλ/ι‐expressing gastric cancer correlated with disease‐specific (P = 0.037) and relapse‐free survival (P = 0.041) by Kaplan–Meier with log‐rank test and higher lymphatic invasion cases by Fisher's exact test (P = 0.042). Furthermore, overexpression of the aPKC‐binding region of KIBRA disrupted tight junctions in epithelial cells. These results suggest that high expression of KIBRA in low aPKC‐expressing cells causes massive loss of aPKC activity, leading to loss of polarity and invasiveness of gastric cancer cells.     

VEGF‐C mediates RhoGDI2‐induced gastric cancer cell metastasis and cisplatin resistance

Rho GDP dissociation inhibitor 2 (RhoGDI2) expression is correlated with tumor growth, metastasis and chemoresistance in gastric cancer. However, the mechanisms by which RhoGDI2 promotes tumor cell survival and metastasis remain unclear. In this study, we clearly demonstrate that RhoGDI2 upregulates VEGF‐C expression and RhoGDI2 expression is positively correlated with VEGF‐C expression in human gastric tumor tissues as well as parental gastric cancer cell lines. VEGF‐C depletion suppressed RhoGDI2‐induced gastric cancer metastasis and sensitized RhoGDI2‐overexpressing cells to cisplatin‐induced apoptosis in vitro and in vivo. Secreted VEGF‐C enhanced gastric cancer cell invasion and conferred cisplatin resistance to RhoGDI2‐overexpressing cells. We also show that RhoGDI2 positively regulates Rac1 activity in gastric cancer cells. Inhibition of Rac1 expression suppressed RhoGDI2‐induced VEGF‐C expression, and this inhibition was associated with decreased invasiveness and increased sensitivity to cisplatin in RhoGDI2‐overexpressing cells. Our results indicate that RhoGDI2 might be a potential therapeutic target for simultaneously reducing metastasis risk and enhancing chemotherapy efficacy in gastric cancer.     

Overexpression of denticleless E3 ubiquitin protein ligase homolog (DTL) is related to poor outcome in gastric carcinoma

Background

Denticleless E3 ubiquitin protein ligase homolog (DTL) has been identified in amplified region (1q32) of several cancers and has an oncogenic function. In this study, we tested whether DTL acts as a cancer-promoting gene through its activation/overexpression in gastric cancer (GC).

Methods

We analyzed 7 GC cell lines and 100 primary tumors that were curatively resected in our hospital between 2001 and 2003.

Results

Overexpression of the DTL protein was detected in GC cell lines (4/7 cell lines; 57%) and primary GC tumor samples (42/100 cases; 42%). Knockdown of DTL using several specific siRNAs inhibited the proliferation, migration and invasion in a TP53 mutation-independent manner. Overexpression of the DTL was significantly correlated with lymphatic invasion, deeper tumor depth and higher recurrence rate. Patients with DTL-overexpressing tumors had a worse survival rate than those with non-expressing tumors in overall survival (P = 0.0498, log-rank test) and disease-free survival (P = 0.0324, log-rank test). In a multivariate analysis, DTL positivity was independently associated with a worse overall survival (P = 0.0104, hazard ratio 3.7 [1.36–10.1]) and disease-free survival (P = 0.0070 (hazard ratio, 3.9 (1.45–10.46)) following radical gastrectomy.

Conclusions

These findings suggest that DTL overexpression plays a crucial role in tumor cell proliferation and highlights its usefulness as a prognosticator and potential therapeutic target in gastric cancer.     

ATP6L promotes metastasis of colorectal cancer by inducing epithelial‐mesenchymal transition

ATP6L, the C subunit of the V‐ATPase V0 domain, is involved in regulating the acidic tumor micro‐environment and may promote tumor progression. However, the expression and functional role of ATP6L in tumors have not yet been well explored. In this study, we found that ATP6L protein overexpression was related to colorectal cancer histological differentiation (P < 0.001), presence of metastasis (P < 0.001) and recurrence (P = 0.02). ATP6L expression in the liver metastatic foci was higher than in the primary foci (P = 0.04). ATP6L expression was notably concomitant with epithelial‐mesenchymal transition (EMT) immunohistochemical features, such as reduced expression of the epithelial marker E‐cadherin (P = 0.021) and increased expression of the mesenchymal marker vimentin (P = 0.004). Results of in vitro and in vivo experiments showed that ATP6L expression could alter cell morphology, regulate EMT‐associated protein expression, and enhance migration and invasion. The effect of ATP6L on metastasis was further demonstrated in a tail vein injection mice model. In addition, the mouse xenograft model showed that ATP6L‐overexpressing HCT116 cells grew into larger tumor masses, showed less necrosis and formed more micro‐vessels than the control cells. Taken together, our results suggest that ATP6L promotes metastasis of colorectal cancer by inducing EMT and angiogenesis, and is a potential target for tumor therapy.     

Integrin α11 in non–small cell lung cancer is associated with tumor progression and postoperative recurrence

Integrins are transmembrane proteins that mediate cell adhesion to the extracellular matrix. Integrin α11 (ITGA11) is not expressed in normal alveolar epithelial cells and is a known receptor for collagen. While integrin α11β1 overexpression in the tumor stroma has been associated with tumor growth and metastatic potential of non–small cell lung cancer (NSCLC), little is known about the role of ITGA11 in tumor cells. Thus, we examined the RNA expression of ITGA11 by quantitative RT‐PCR in 80 samples collected from NSCLC patients who had undergone surgical resection and analyzed the clinical outcomes. We found that high expression of ITGA11 was associated with lower recurrence‐free survival in all NSCLC patients (P = 0.043) and in stage I NSCLC patients (P = 0.049). These results were consistent with in silico analyses of the Cancer Genome Atlas database. We also analyzed cell proliferation, migration and invasion capacity in lung cancer cell lines after overexpression of ITGA11. Overexpression of ITGA11 in lung cancer cell lines had little effect on cell proliferation but resulted in increased migration and invasion capacity. Our findings suggest that ITGA11 plays a significant role in cancer migration and invasion, leading to higher recurrence. ITGA11 expression may be a predictor of poor prognosis in patients with surgically resected NSCLC.     

HOXB7 promotes invasion and predicts survival in pancreatic adenocarcinoma

BACKGROUND:

The homeobox gene HOXB7 is overexpressed across a range of cancers and promotes tumorigenesis through varying effects on proliferation, survival, invasion, and angiogenesis. Although published microarray data suggest HOXB7 is overexpressed in pancreatic ductal adenocarcinoma (PDAC), its function in pancreatic cancer has not been studied.

METHODS:

HOXB7 message and protein levels were examined in PDAC cell lines and patient samples, as well as in normal pancreas. HOXB7 protein expression in patient tumors was determined by immunohistochemistry and correlated with clinicopathologic factors and survival. The impact of HOXB7 on cell proliferation, growth, and invasion was assessed by knockdown and overexpression in PDAC cell lines. Candidate genes whose expression levels were altered following HOXB7 knockdown were determined by microarray analysis.

RESULTS:

HOXB7 message and protein levels were significantly elevated in PDAC cell lines and patient tumor samples relative to normal pancreas. Evaluation of a tissue microarray of 145 resected PDACs found high HOXB7 protein expression was correlated with lymph node metastasis (P = .034) and an independent predictor of worse overall survival in multivariate analysis (hazard ratio = 1.56, 95% confidence interval = 1.02‐2.39). HOXB7 knockdown or overexpression in PDAC cell lines resulted in decreased or increased invasion, respectively, without influencing proliferation or cell viability.

CONCLUSIONS:

HOXB7 is frequently overexpressed in PDAC, specifically promotes invasive phenotype, and is associated with lymph node metastasis and worse survival outcome. HOXB7 and its downstream targets may represent novel clinical biomarkers or targets of therapy for inhibiting the invasive and metastatic capacity of PDAC. Cancer 2013. © 2012 American Cancer Society.     

TRIM44 promotes human esophageal cancer progression via the AKT/mTOR pathway

Aberrant expression of TRIM‐containing protein 44 (TRIM44) acts as a promoter in multiple cancers. Here, we investigated the biological functions and clinical significance of TRIM44 in human esophageal cancer (HEC). TRIM44 expression was significantly higher in HEC tissues than corresponding normal tissues at both the mRNA (2.42 ± 0.52 vs 0.99 ± 0.25) and protein (1.01 ± 0.27 vs 0.30 ± 0.13) levels. Patients with high TRIM44 expression showed poor differentiation (P = 1.39 × 10^?5), advanced TNM stage (P = 3.87 × 10^?4) and, most importantly, significantly poorer prognosis (P = 2.80 × 10^?5). TRIM44 played a crucial role in epithelial mesenchymal transition (EMT). A significant correlation was observed between TRIM44 and Ki67 expression. We demonstrated that TRIM44 markedly enhanced HEC cell proliferation, migration, and invasion. Additionally, TRIM44 was involved in the AKT/mTOR signaling pathway and its downstream targets, such as STAT3 phosphorylation. Thus, elevated TRIM44 expression promotes HEC development by EMT via the AKT/mTOR pathway, and TRIM44 may be a novel prognostic indicator for HEC patients after curative resection.     

ASP5878, a selective FGFR inhibitor,to treat FGFR3‐dependent urothelial cancer with or without chemoresistance

FGF/FGFR gene aberrations such as amplification, mutation and fusion are associated with many types of human cancers including urothelial cancer. FGFR kinase inhibitors are expected to be a targeted therapy for urothelial cancer harboring FGFR3 gene alternations. ASP5878, a selective inhibitor of FGFR1, 2, 3 and 4 under clinical investigation, selectively inhibited cell proliferation of urothelial cancer cell lines harboring FGFR3 point mutation or fusion (UM‐UC‐14, RT‐112, RT4 and SW 780) among 23 urothelial cancer cell lines. Furthermore, ASP5878 inhibited cell proliferation of adriamycin‐resistant UM‐UC‐14 cell line harboring MDR1 overexpression and gemcitabine‐resistant RT‐112 cell line. The protein expression of c‐MYC, an oncoprotein, in gemcitabine‐resistant RT‐112 cell line was higher than that in RT‐112 parental cell line and ASP5878 decreased the c‐MYC expression in both RT‐112 parental and gemcitabine‐resistant RT‐112 cell lines. Once‐daily oral administration of ASP5878 exerted potent antitumor activities in UM‐UC‐14, RT‐112 and gemcitabine‐resistant RT‐112 xenograft models without affecting body weight. These findings suggest that ASP5878 has the potential to be an oral targeted therapy against urothelial cancer harboring FGFR3 fusion or FGFR3 point mutation after the acquisition of gemcitabine‐ or adriamycin‐resistance.     

Macrophage migration inhibitory factor induces epithelial to mesenchymal transition,enhances tumor aggressiveness and predicts clinical outcome in resected pancreatic ductal adenocarcinoma

MIF is a proinflammatory cytokine and is implicated in cancer. A higher MIF level is found in many human cancer and cancer‐prone inflammatory diseases, including chronic pancreatitis and pancreatic cancer. We tested the hypothesis that MIF contributes to pancreatic cancer aggressiveness and predicts disease outcome in resected cases. Consistent with our hypothesis we found that an elevated MIF mRNA expression in tumors was significantly associated with poor outcome in resected cases. Multivariate Cox‐regression analysis further showed that MIF is independently associated with patients' survival (HR = 2.26, 95% CI = 1.17–4.37, p = 0.015). Mechanistic analyses revealed that MIF overexpression decreased E‐cadherin and increased vimentin mRNA and protein levels in pancreatic cancer cell lines, consistent with the features of epithelial‐to‐mesenchymal transition (EMT). Furthermore, MIF‐overexpression significantly increased ZEB1/2 and decreased miR‐200b expression, while shRNA‐mediated inhibition of MIF increased E‐cadherin and miR‐200b expression, and reduced the expression of ZEB1/2 in Panc1 cells. Re‐expression of miR‐200b in MIF overexpressing cells restored the epithelial characteristics, as indicated by an increase in E‐cadherin and decrease in ZEB1/2 and vimentin expression. A reduced sensitivity to the chemotherapeutic drug, gemcitabine, occurred in MIF‐overexpressing cells. Indicative of an increased malignant potential, MIF over‐expressing cells showed significant increase in their invasion ability in vitro, and tumor growth and metastasis in an orthotopic xenograft mouse model. These results support a role of MIF in disease aggressiveness, indicating its potential usefulness as a candidate target for designing improved treatment in pancreatic cancer.     

Cigarette smoking, body mass index, gastro-esophageal reflux disease, and non-steroidal anti-inflammatory drug use and risk of subtypes of esophageal and gastric cancers by P53 overexpression

A number of risk factors for esophageal and gastric cancers have emerged, yet little is known whether risk factors map to molecular tumor markers such as overexpression of the tumor suppressor TP53. Using a US multicenter, population-based case–control study (170 cases of esophageal adenocarcinomas, 147 gastric cardia adenocarcinomas, 220 non-cardia gastric adenocarcinomas, and 112 esophageal squamous cell carcinomas), we examined whether the risk associated with cigarette smoking, body mass index (BMI), gastroesophageal reflux disease (GERD), and non-steroidal anti-inflammatory drug (NSAID) use varied by P53 overexpression. We defined P53 overexpression through immunohistochemistry of paraffin-embedded tumor tissues, using cutpoints based on percent of cells positive. Polytomous logistic regression was used to assess differences between each case group (defined by tumor subtype and P53 expression) and the control group by risk factors. The proportion of cases overexpressing P53 by tumor subtype was 72% for esophageal adenocarcinoma, 69% for gastric cardia adenocarcinoma, 52% for non-cardia gastric adenocarcinoma, and 67% for esophageal squamous cell carcinoma. For most tumor subtypes, we found little difference in risk factors by tumor P53 overexpression. For non-cardia gastric cancer however, an association with cigarette smoking was suggested for tumors that do not overexpress P53, whereas larger BMI was related to adenocarcinomas that overexpress P53 versus no overexpression. Overall, this study did not find a clear relationship between P53 protein overexpression and the known risk factors for subtypes of esophageal and gastric cancers. Further research on these tumors is needed to identify molecular markers associated with variations in the risk factor profiles.     

High expression of α 2, 3-linked sialic acid residues is associated with the metastatic potential of human gastric cancer

Background: Sialic acid, as a terminal saccharide residue on cell surface glycoconjugates, plays an important role in a variety of biological processes. However, the precise nature of the molecules in gastric cancers has not been unveiled nor documented to be of clinical relevance. Herein, we measured the expression of α 2, 3-linked sialic acid residues by using a specific lectin as well as the potential of invasion and metastasis of gastric cancer was analyzed. Methods: The expression of α 2, 3-linked sialic acid residues in 100 cases of gastric cancer samples was evaluated using Maackia amurensis leukoagglutinin (MAL) histochemical staining analysis. The assays of cytochemical staining and flow cytometry were employed to determine the MAL positive cells in the gastric cancer cell lines. The activities of invasion and migration were evaluated using the assays of cell adhesion and transwell chamber. Results: The staining of MAL in gastric cancer tissues showed that high levels of α 2, 3-linked sialic acid residues were closely associated with the invasive depth (P = 0.0003) and lymph node metastasis (P = 0.0441). In gastric adenocarcinoma cell lines, SGC-7901, the highly metastatic cell line, displayed the most positive reaction with MAL among the selected cell lines. The potential of invasion and migration was confirmed using the assays of adhesion and transwell chamber that SGC-7901 exhibited the high activity of adhesion to extracellular matrix (ECM) and penetration to Matrigel. Conclusion: These results suggested that high level of α 2, 3-linked sialic acid residues was associated with metastatic potential of gastric cancer cells.     

Expression of the MAP kinase phosphatase DUSP4 is associated with microsatellite instability in colorectal cancer (CRC) and causes increased cell proliferation

DUSP4 (MKP‐2), a member of the mitogen‐activated protein kinase phosphatase (MKP) family and potential tumor suppressor, negatively regulates the MAPKs (mitogen‐activated protein kinases) ERK, p38 and JNK. MAPKs play a crucial role in cancer development and progression. Previously, using microarray analyses we found a conspicuously frequent overexpression of DUSP4 in colorectal cancer (CRC) with high frequent microsatellite instability (MSI‐H) compared to microsatellite stable (MSS) CRC. Here we studied DUSP4 expression on mRNA level in 38 CRC (19 MSI‐H and 19 MSS) compared to matched normal tissue as well as in CRC cell lines by RT‐qPCR. DUSP4 was overexpressed in all 19 MSI‐H tumors and in 14 MSS tumors. Median expression levels in MSI‐H tumors were significantly higher than in MSS‐tumors (p < 0.001). Consistently, MSI‐H CRC cell lines showed 6.8‐fold higher DUSP4 mRNA levels than MSS cell lines. DUSP4 expression was not regulated by promoter methylation since no methylation was found by quantitative methylation analysis of DUSP4 promoter in CRC cell lines neither in tumor samples. Furthermore, no DUSP4 mutation was found on genomic DNA level in four CRC cell lines. DUSP4 overexpression in CRC cell lines through DUSP4 transfection caused upregulated expression of MAPK targets CDC25A, CCND1, EGR1, FOS, MYC and CDKN1A in HCT116 as well as downregulation of mismatch repair gene MSH2 in SW480. Furthermore, DUSP4 overexpression led to increased proliferation in CRC cell lines. Our findings suggest that DUSP4 acts as an important regulator of cell growth within the MAPK pathway and causes enhanced cell growth in MSI‐H CRC.     

Peroxisome proliferator‐activated receptor γ upregulates galectin‐9 and predicts prognosis in intestinal‐type gastric cancer

The importance of PPARγ (peroxisome proliferator‐activated receptor γ) in gastric cancer (GC) is unclear. We investigated the role of PPARγ in GC cell lines and an animal model, and its prognostic significance of PPARγ in GC patients. We controlled PPARγ and galectin‐9 expression by using siRNAs and lentiviral constructs. Interaction between PPARγ and galectin‐9 was evaluated using luciferase and chromatin immunoprecipitation assays. PPARγ expression in GCs was determined by immunohistochemical staining of tissue microarrays and survival analysis was done. Overexpression of PPARγ was accompanied by increased galectin‐9. Enhanced PPARγ or galectin‐9 expression increased E‐cadherin expression; decreased expression of N‐cadherin, fibronectin, snail, twist and slug and reduced cell invasion and migration. PPARγ bound to the galectin‐9 promoter region. Galectin‐9 activity increased in PPARγ‐overexpressing cells but decreased in PPARγ siRNA‐treated cells. In a zebrafish xenograft model, the number of migrated cancer cells and number of fish with AGS cells in the tail vein were reduced in PPARγ‐overexpressing GC cells. PPARγ was expressed in 462 of the 688 patients (69.2%) with GC. In 306 patients with intestinal‐type GC, those with PPARγ‐positive tumors had lower overall and cancer‐specific mortalities than those with PPARγ‐negative tumors. PPARγ expression was an independent prognostic factor for overall and GC‐specific mortality in patients with intestinal‐type GC (adjusted hazard ratio, 0.42; 95% CI, 0.22–0.81). PPARγ inhibits cell invasion, migration and epithelial–mesenchymal transition through upregulation of galectin‐9 in vitro and in vivo.