Mitogen-activated Protein Kinase Kinase 4 Gene Research Articles

MKK4 variants rs3826392 and rs3809728 are associated with susceptibility and clinicopathological features in colorectal cancer patients.

Objective(s):The mitogen-activated protein kinase kinase 4 (MKK4) plays a key role in several processes like inflammation, apoptosis, and tumorigenesis. Several authors have proposed that genetic variations in these genes may alter their expression with subsequent cancer risk. This study aimed to examine the possible association of MKK4 rs3826392 and rs3809728 variants in Mexican patients with colorectal cancer (CRC). These variants were also compared with clinical features as sex, age, TNM stage, and tumor location.Materials and Methods:The study included genomic DNA from 218 control subjects and 250 patients. Genotyping of the MKK4 variants was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) procedure. Results:Individuals with A/T and T/T genotypes for the rs3809728 (-1044 A>T) variant showed a significantly increased risk for CRC (P=0.012 and 0.007, respectively); while individuals with the G/G genotype for the rs3826392 (-1304 T>G) variant showed a decreased risk for CRC (P=0.012). Genotypes of the MKK4 rs3809728 variant were also significantly related to colon localization and advanced TNM stage in CRC patients. T-T haplotype (rs3826392 and rs3809728) of the MKK4 gene was associated with risk in patients with CRC.Conclusion:The rs3826392 variant in the MKK4 gene could be a cancer protective factor, while the rs3809728 variant could be a risk factor. These variants play a significant role in CRC risk.

Evaluation of the association between the -1304T>G polymorphism in the promoter of the MKK4 gene and the risk of colorectal cancer: a PRISMA-compliant meta-analysis.

Colorectal cancer (CRC) is one of the most common cancers in China. Mitogen-activated protein kinase kinase 4 (MKK4) regulates tumorigenesis as a component of the MKK4 pathway. A number of studies have suggested a correlation between the MKK4 -1304T>G polymorphism and the risk of CRC. However, the results are still controversial. Therefore, we conducted a meta-analysis to obtain a more accurate assessment of the association between the MKK4 -1304T>G polymorphism and the risk of CRC. Systematic literature searches were performed using PubMed, Embase, Cochrane Library, and CNKI. Four trials, including 1,255 cancer cases and 1,181 controls, were recruited in our study to assess the relationship of the MKK4 -1304T>G polymorphism with the risk of CRC. Four studies met our inclusion criteria and were finally included in the analysis, involving 1,255 cancer patients and 1,181 controls. Our meta-analysis revealed that the MKK4 -1304T>G polymorphism could reduce the risk of CRC (G vs. T: OR, 0.60, 95% CI: 0.48-0.76, P<0.0001; GG vs. TT: OR, 0.43, 95% CI: 0.29-0.62, P<0.0001; GG vs. TT + TG: OR, 0.50, 95% CI: 0.34-0.72, P=0.0003; TG + GG vs. TT: OR, 0.62, 95% CI: 0.53-0.73, P<0.0001; and TG vs. TT + GG: OR, 0.70, 95% CI: 0.59-0.82, P<0.0001). In conclusion, our meta-analysis showed that the MKK4 -1304T>G polymorphism was associated with the susceptibility to CRC. In the future, large and well-designed case-control studies are needed to validate our findings.

The Association Between -1304T&gt;G Polymorphism in the Promoter of Mitogen-Activated Protein Kinase Kinase 4 Gene and the Risk of Cervical Cancer in Chinese Population

Mitogen-activated protein kinase kinase 4 (MKK4) is a critical mediator of stress-activated protein kinase signals that regulate apoptosis, inflammations, and tumorigenesis. Several polymorphisms have been identified in the MKK4 gene. We hypothesized that genetic variants in the MKK4 promoter may alter its functions and thus cancer risk. In the current, hospital-based case-control study of 471 cervical cancer cases and 600 sex and age frequency-matched cancer-free controls in an Eastern Chinese population, we genotyped two common polymorphisms in the MKK4 promoter region (-1304T>G, rs3826392 and -1044A>T, rs3809728)c and assessed their associations with the risk of cervical cancer. We found that compared with the most common -1304TT genotype, carriers of -1304G variant genotypes had a significantly decreased risk of cervical cancer [odds ratio (OR) = 0.71; 95% confidence interval (CI) = 0.53-0.92 for TG, and OR = 0.52; 95%CI = 0.30-0.91 for GG] in an allele dose-response manner (adjusted P(trend) = 0.004). Moreover, the luciferase assay showed that the G allele in the promoter significantly increased the transcription activity of the MKK4 gene in vitro and that the MKK4 mRNA expression levels of the G variant carriers was significantly higher in tumor tissues than those of the -1304TT genotype. However, no significant association was observed between the -1044A>T polymorphism and risk of cervical cancer. Our data suggest that the functional -1304G variant in the MKK4 promoter contributes to a decreased risk of cervical cancer by increasing the promoter activity and that the G variant may be a marker for susceptibility to cervical cancer.

Functional and Clinicopathological Analysis of Loss of MKK4 Expression in Endometrial Cancer

Objective: In the current study, we investigated the mechanism relating downregulation of mitogen-activated protein kinase kinase-4 (MKK4) expression to the development of endometrial cancer. Methods: MKK4 expression in endometrial cancer was assessed by immunohistochemistry using 87 paraffin-embedded tissue specimens, and clinical data was collected via a retrospective chart review. MKK4 gene knockdown using silencing RNA and an MKK4 gene transfection system was used to assess MKK4 function in tissue samples of endometrial cancer. Results: Lower expression of MKK4 immunointensity was observed in 63.2% (55/87) of the analyzed tumors. High-grade endometrioid adenocarcinoma (G2 and G3) (p = 0.024), postmenopausal status (p = 0.018), and patient age (≧60) (p = 0.012) were significantly correlated with lower MKK4 expression. Patients with lower MKK4 expression in endometrial cancer tissues tended to have a shorter overall survival (p = 0.197). Using cell growth and anchorage-independent assays, we determined that both the growth and colony-forming ability of MKK4-transfected HEC1B cells, a line with a low endogenous expression of MKK4, were significantly reduced compared to control vector-transfected cells. Overexpression of the MKK4 gene in HEC1B cells resulted in reduced cell migration activity in a simulated wound healing assay. To confirm that MKK4 expression is related to tumor suppressor function, we used 2 independent but complementary approaches. MKK4 gene knockdown in JHEM1 cells, which overexpressed MKK4, increased proliferation activity. Additionally, the engineered expression of MKK4 in Ishikawa cells, a line with low endogenous MKK4 expression, produced a phenotype similar to that of HEC1B. Similar results were produced in tumor xenografts in nude mice. Conclusion: These results indicate that MKK4 acts as a tumor suppressor, and reduced expression of MKK4 may contribute to the development of endometrial cancer.

Loss of MKK4 expression in ovarian cancer: A potential role for the epithelial to mesenchymal transition

In the current study, we investigated the mechanism relating downregulation of mitogen-activated protein kinase kinase 4 (MKK4) expression to development of ovarian cancer. Over-expression of the MKK4 gene in TOV-21 G cells, a line with homozygous deletion of MKK4, resulted in morphologic changes in which cells growing in a scattered, fibroblast-like pattern formed tightly packed colonies. Based on a wound healing assay and a Matrigel invasion assay, we determined that both motility and invasiveness of MKK4-transfected TOV-21G cells were significantly reduced compared to control vector-transfected cells. To confirm that MKK4 expression related to tumor invasion resulted from an epithelial to mesenchymal transition (EMT)-like morphological change, we used 2 independent but complementary approaches. MKK4 gene knockdown in MDAH 2774 cells over-expressing MKK4 increased invasion activity. Additionally, engineered expression of MKK4 in SKOV3 cells, a line with low endogenous MKK4 expression, produced a phenotype similar to that of TOVG-21G. Interestingly, we found that MKK4 upregulation caused downregulation of phosphorylated NF-κB and Twist, as well as upregulation of E-cadherin, in TOVG-21G and SKOV3 cells. Reciprocal results were obtained in MDAH 2774 cells with MKK4 knockdown. Our results suggest that MKK4 downregulation causes increased phosphorylation NF-κB. This promotes Twist over-expression, resulting in E-cadherin downregulation that induces EMT in ovarian cancer.

Increased Adipose Tissue Expression of Proinflammatory CD40, MKK4 and JNK in Patients with Very Severe Chronic Obstructive Pulmonary Disease

Background: CD40, a transmembrane receptor of the tumor necrosis factor gene superfamily, is activated in response to cellular stress, including hypoxia, and orchestrates the process of inflammation via secondary messengers such as mitogen-activated protein kinase kinase 4 (MKK4) and c-Jun NH₂-terminal kinases (JNK). Objectives: We hypothesized that CD40, MKK4 and JNK expression is increased in the adipose tissue of patients with very severe chronic obstructive pulmonary disease (COPD). Methods: In 20 patients with stable COPD, lung function was assessed using body plethysmography, and samples of subcutaneous adipose tissue were analyzed using real-time PCR. Body composition, including fat mass index (FMI), was assessed by bioelectrical impedance. Results: 12 patients in GOLD stage I–III (age 61.6 ± 8.6 years, 4 females, mean partial pressure of oxygen in arterial blood, PaO₂, 9.38 ± 0.21 kPa) were compared to 8 patients in GOLD stage IV (age 62.6 ± 6.3 years, all male, mean PaO₂ 7.70 ± 0.37 kPa). Compared to patients in GOLD stage I–III, patients in GOLD stage IV had lower FMI (p = 0.004), being associated with significantly higher adipose tissue expression of CD40, MKK4 and JNK [ΔΔCt: 2.55 (1.99, 4.40) vs. 1.87 (1.63, 2.23), p = 0.013; 5.19 (3.13, 5.96) vs. 2.98 (2.82, 3.86), p = 0.002; 9.01 (5.12, 11.41) vs. 4.65 (4.42, 6.26), p = 0.001, respectively]. Log-transformed CD40, MKK4 and JNK expression was significantly inversely related to PaO₂, respectively. Conclusions: Upregulation of proinflammatory CD40, MKK4 and JNK gene expression in adipose tissue in very severe COPD raises the possibility of a role of chronic systemic hypoxia in the pathogenesis of adipose tissue inflammation in COPD.

A functional variant (−1304T&gt;G) in the MKK4 promoter contributes to a decreased risk of lung cancer by increasing the promoter activity

Mitogen-activated protein kinase kinase 4 (MKK4) is a critical mediator of stress-activated protein kinase signals that regulate apoptosis, inflammations and tumorigenesis. Several polymorphisms have been identified in the MKK4 gene. We hypothesized that genetic variants in the MKK4 promoter may alter its expression and thus cancer risk. In a case-control study of 1056 lung cancer cases and 1056 sex and age frequency-matched cancer-free controls, we genotyped two common polymorphisms in the MKK4 promoter region (-1304T>G and -1044A>T) with the Taqman assay, and we found that compared with the most common -1304TT genotype, carriers of -1304G variant genotypes had a decreased risk of lung cancer [odds ratio (OR) = 0.74; 95% confidence interval (CI) = 0.61-0.90 for TG, and OR = 0.62; 95% CI = 0.41-0.94 for GG] in an allele dose-response manner (adjusted P(trend) = 0.0005). Further stratification analysis showed that the protective role of the -1304G variant allele was more evident in low or normal body mass index (BMI) but restrained in the overweighters and that the -1304G variant genotypes interacted with BMI in reducing cancer risk (adjusted P(interaction) = 0.003). Moreover, the luciferase assay showed that the G allele in the promoter significantly increased the transcription activity of the MKK4 gene in vitro and that the MKK4 protein expression levels of the G variant carriers was significantly higher in tumor tissues than those of the -1304TT genotype. However, no significant association was observed between the -1044A>T polymorphism and risk of lung cancer. Our data suggest that the functional -1304G variant in the MKK4 promoter contributes to a decreased risk of lung cancer by increasing the promoter activity and that the G variant may be a marker for susceptibility to lung cancer.

The association between −1304T&gt;G polymorphism in the promoter of MKK4 gene and the risk of sporadic colorectal cancer in southern Chinese population

MKK4 (mitogen-activated protein kinase kinase 4, NM_003010.2), which belongs to the mitogen-activated protein kinase pathways, possesses functions in tumorigenesis. We hypothesized the genetic variants in MKK4 gene may alter its functions and thus cancer risk. In current hospital-based case-control study of 706 patients with sporadic colorectal cancer (CRC) and 723 sex-age-frequency-matched control subjects in a southern Chinese population, we genotyped two polymorphisms of MKK4 promoter (i.e., -1304T>G, rs3826392 and -1044A>T, rs3809728) and assessed their associations with the risk of sporadic CRC. Compared with -1304TT genotypes, -1304TG had a significantly decreased risk of CRC (adjusted odds ratios [OR] = 0.56; 95% CI = 0.44-0.72; p = 3.53 x 10(-6)), the -1304GG carriers had a further decreased risk of CRC (OR = 0.40; 95% CI = 0.23-0.70; p = 1.32 x 10(-3)), and there was a significant trend for an allele dose effect on risk of CRC (p(trend) = 2.64 x 10(-7)). The decreased risk associated with -1304G variant genotypes (i.e., TG+GG) was more pronounced in the subjects older than 60 years (adjusted OR = 0.41; 95% CI = 0.29-0.57; p = 2.25 x 10(-7)), in ever drinkers (adjusted OR = 0.41; 95% CI = 0.28-0.59; p = 2.42 x 10(-6)). The age and alcohol drinking status interacted with -1304G variant genotypes on reducing cancer risk (p values for interaction were 0.015 and 0.043, respectively). Western blotting analysis showed that the levels of Mkk4 protein in sporadic CRC neoplastic tissues were significantly higher in the carriers of -1304G variant genotypes than that in those with -1304TT genotypes. However, no significant association was observed between -1044A>T polymorphism and risk of CRC. To the best of our knowledge, this is the first study of genetic variants in MKK4 and cancer susceptibility. Larger studies are needed to validate our findings.

Mitogen-activated protein kinase kinase 4 and tumor metastasis

Mitogen-activated protein kinase kinase 4(MKK4)is an important component of mitogenactivated protein kinase(MAPK)signaling conduction.It is highly related with tumors formation and metastasis,It is reported that loss of MKK4 gene functional mutations is found in approximately 5%of tumors of a variety of tissues,suggesting it may be a tumor suppresser gene.MKK4 also has been identified as a suppressor gene in tumors metastasis,which can suppress many tumors metastasis. Key words: MAP kinase kinase 4; Neoplasm metastasis

Role of mitogen-activated protein kinase kinase 4 in cancer

Mitogen-activated protein (MAP) kinase kinase 4 (MKK4) is a component of stress activated MAP kinase signaling modules. It directly phosphorylates and activates the c-Jun N-terminal kinase (JNK) and p38 families of MAP kinases in response to environmental stress, pro-inflammatory cytokines and developmental cues. MKK4 is ubiquitously expressed and the targeted deletion of the Mkk4 gene in mice results in early embryonic lethality. Further studies in mice have indicated a role for MKK4 in liver formation, the immune system and cardiac hypertrophy. In humans, it is reported that loss of function mutations in the MKK4 gene are found in approximately 5% of tumors from a variety of tissues, suggesting it may have a tumor suppression function. Furthermore, MKK4 has been identified as a suppressor of metastasis of prostate and ovarian cancers. However, the role of MKK4 in cancer development appears complex as other studies support a pro-oncogenic role for MKK4 and JNK. Here we review the biochemical and functional properties of MKK4 and discuss the likely mechanisms by which it may regulate the steps leading to the formation of cancers.

Expression and mutation analyses of MKK4, a candidate tumour suppressor gene encoded by chromosome 17p, in human gastric adenocarcinoma

Homozygous deletion or somatic mutations of mitogen-activated protein kinase kinase 4 (MKK4), a candidate tumour suppressor gene located at 17p11, have been observed in many types of human tumours. To explore the likelihood that MKK4 acts as a suppressor in gastric tumorigenesis, we examined the expression and mutation status of MKK4 in 144 gastric tissues and cell line specimens. Expression of the MKK4 transcript was easily detectable in all normal and benign tumour tissues and none of 102 primary carcinomas and cell lines showed an abnormal reduction in MKK4 expression. Expression levels of MKK4 transcript showed no cancer-specific reduction in 43 matched sets and did not correlate with stage, grade and histopathological types of the tumours. Western blot analysis also revealed that MKK4 protein expression in carcinoma tissues and cell lines is comparable to non-cancerous tissues. A significant loss of heterozygosity (LOH) was detected at telomeric markers of the MKK4, locus. However, no allelic deletion of the MKK4 gene or at the centromeric loci was identified. Moreover, no evidences for somatic mutations leading to amino acid substitutions or frameshifts of MKK4 were identified in the carcinoma tissues and cell lines, whereas a substantial fraction of the same set showed allelic loss or mutations of the TP53 gene located at 17p13, suggesting that LOH at telomeric loci or the TP53 locus might not extend into the MKK4 gene in gastric cancers. In this study, we also report the identification of a highly conserved MKK4 processed pseudogene, which shares 95% homology with the coding region of the functional MKK4 transcript. Collectively, our data demonstrate that genomic deletion or somatic mutation of MKK4 is infrequent in gastric cancers, suggesting that MKK4 might not be a critical target of genetic inactivation in gastric tumorigenesis.

Mitogen-Activated Protein Kinase Kinase 4 (MKK4)

The Mitogen-Activated Protein Kinase Kinase 4 (MKK4), a member of the MAP kinase kinase family, directly phosphorylates and activates the c-Jun NH2-terminal kinases (JNK), in response to cellular stresses and proinflammatory cytokines. JNK is a member of the MAP kinase family and a key component of a stress activated protein kinase signalling pathway. MKK4 mRNA is widely expressed in adult mouse tissues, but is especially abundant in skeletal muscle and brain. Mice lacking the MKK4 gene had abnormal hepatogenesis and died before embryonic day 14. However cell lines lacking MKK4 have been obtained and these exhibited defective activation of JNK and AP-1 dependent transcription activity in response to some, but not all cellular stresses. Furthermore, T lymphocytes deficient in MKK4 showed impaired IL-2 production following activation of the T cell receptor, suggesting a key role of the MKK4/JNK pathway in inflammation. The mutation of the MKK4 gene in some carcinomas indicates that it may also have a role as a tumor suppressor. Control of the MKK4 activity and expression may provide novel approaches to cancer or anti-inflammatory therapy.