Epigenetic regulation of the transcription factor Foxa2 directs differential elafin expression in melanocytes and melanoma cells

Silencing of FOXA2 decreases E-cadherin expression and is associated with lymph node metastasis in oral cancer

OBJECTIVES

FOXA2 gene methylation links to the progression of cancers, but has not been documented in oral cancer. Herein, we explore the role of FOXA2 in the migration of oral cancer cells.

MATERIAL AND METHODS

Methylation-specific PCR was applied for gene methylation. Wound healing and transwell experiments were tested for cell migration. FOXA2 expression in oral cancer tissues was addressed by immunohistochemistry, followed by statistical analysis of its association with clinical manifestations and patient survival.

RESULTS

FOXA2 bound to the promoter of CDH1 and enhanced the expression of its gene product E-cadherin, and decreased the cancer cell migration activity. High FOXA2 expression in oral cancer tissues was associated with high E-cadherin expression, decreased lymph node metastasis, and increased patient survival.

CONCLUSION

FOXA2-E-cadherin link is involved in regulation of oral cancer cell metastasis and provides a new insight for the tumor suppressor activity of FOXA2 in oral cancer.

MicroRNA-1246 Promotes Melanoma Progression Through Targeting FOXA2

Introduction

Recently, the incidence of melanoma has been rising and there is a lack of effective targeted therapies. The regulatory mechanisms of microRNA-1246 (miR-1246) have been found in many cancers, except melanoma. This study focused on the regulatory mechanism of miR-1246 in melanoma development.

Methods

The expression of miR-1246 was assessed using quantitative real-time polymerase chain reaction (RT-qPCR). Cell viability and metastasis were detected by Transwell and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assays. The protein expression of epithelial mesenchymal transition (EMT) makers was assessed by Western blot analysis. The target gene of miR-1246 was detected using luciferase reporter assay.

Results

MiR-1246 expression was increased in melanoma tissues and cells. In addition, upregulation of miR-1246 promoted cell viability and metastasis in melanoma. Forkhead box protein A2 (FOXA2) was confirmed to be a direct target of miR-1246. And FOXA2 expression was decreased in melanoma and was suppressed by miR-1246. Importantly, upregulation of FOXA2 restored the carcinogenesis of miR-1246 in melanoma.

Conclusion

MiR-1246 promoted cell viability and metastasis in melanoma by inhibiting FOXA2 expression.

Hepatocyte Nuclear Factor 3β Plays a Suppressive Role in Colorectal Cancer Progression

Background and Objective: Hepatocyte nuclear factor 3β (HNF3β) is a key transcription factor in the development of the gastrointestinal tract. However, only few studies have examined its' expression, function and potential clinical significance in colorectal cancer tumorigenesis and progression.

Methods: HNF3β expression in colorectal cancer tissue samples of 174 patients was assessed by immunohistochemistry. The results were analyzed with respect to patients' clinicopathological characteristics and survival. Following the in vitro cell transfection, MTT, wound healing, and Transwell assays were used to test cell proliferation, migration, and invasion, respectively. Western blot was used to examine IL6, JAK1, and STAT3 protein expression. The potential for tumor formation was evaluated using a mouse xenograft model.

Results: HNF3β expression was lower in colon cancer tissue compared to normal tissue and correlated with UICC clinical stage (P = 0.001), depth of invasion (P = 0.004), regional lymph node metastasis (P = 0.007), distant metastasis (P = 0.048), and poor survival (P < 0.001) in patients with colorectal cancer. Furthermore, HNF3β overexpression impeded proliferation, migration and invasion of SW480 cells via JAK-STAT3 signaling in vitro. Moreso, HNF3β overexpression showed a significant growth inhibition of subcutaneous xenograft tumors in vivo.

Conclusions: The results show that HNF3β acts as a suppressor of colorectal cancer progression and decreased HNF3 β expression is closely related to the poor prognosis. Thus, HNF3β may be a potential molecular target for inhibition of colorectal cancer cells and development of new anti-tumor therapies.

Prediction of tissue-specific effects of gene knockout on apoptosis in different anatomical structures of human brain

BACKGROUND

An important issue in the target identification for the drug design is the tissue-specific effect of inhibition of target genes. The task of assessing the tissue-specific effect in suppressing gene activity is especially relevant in the studies of the brain, because a significant variability in gene expression levels among different areas of the brain was well documented.

RESULTS

A method is proposed for constructing statistical models to predict the potential effect of the knockout of target genes on the expression of genes involved in the regulation of apoptosis in various brain regions. The model connects the expression of the objective group of genes with expression of the target gene by means of machine learning models trained on available expression data. Information about the interactions between target and objective genes is determined by reconstruction of target-centric gene network. STRING and ANDSystem databases are used for the reconstruction of gene networks. The developed models have been used to analyse gene knockout effects of more than 7,500 target genes on the expression of 1,900 objective genes associated with the Gene Ontology category "apoptotic process". The tissue-specific effect was calculated for 12 main anatomical structures of the human brain. Initial values of gene expression in these anatomical structures were taken from the Allen Brain Atlas database. The results of the predictions of the effect of suppressing the activity of target genes on apoptosis, calculated on average for all brain structures, were in good agreement with experimental data on siRNA-inhibition.

CONCLUSIONS

This theoretical paper presents an approach that can be used to assess tissue-specific gene knockout effect on gene expression of the studied biological process in various structures of the brain. Genes that, according to the predictions of the model, have the highest values of tissue-specific effects on the apoptosis network can be considered as potential pharmacological targets for the development of drugs that would potentially have strong effect on the specific area of the brain and a much weaker effect on other brain structures. Further experiments should be provided in order to confirm the potential findings of the method.

The serine protease inhibitor elafin maintains normal growth control by opposing the mitogenic effects of neutrophil elastase

The serine protease inhibitor, elafin, is a critical component of the epithelial barrier against neutrophil elastase (NE). Elafin is downregulated in the majority of breast cancer cell lines compared to normal human mammary epithelial cells (HMECs). Here, we evaluated the role of elafin and NE on proliferation and tumorigenesis. Elafin is induced in growth factor deprived HMECs as they enter a quiescent (G0) state, suggesting that elafin is a counterbalance against the mitogenic effects of NE in G0 HMECs. Stable knockdown of elafin compromises the ability of HMECs to maintain G0-arrest during long-term growth factor deprivation; this effect can be reversed by re-expression of wild-type elafin, but not elafin-M25G lacking protease inhibitory function. These results suggest that NE, which is largely contributed by activated neutrophils in the tumor microenvironment, may be negatively regulating the ability of elafin to arrest cells in G0. In fact when purified NE was added to elafin knockdown HMECs, these cells demonstrated greater sensitivity to the growth promoting effects of purified NE. Activation of ERK signaling, downstream of toll-like receptor 4, was essential to the mitogenic effect of NE on HMECs. These findings were next translated to patient samples, and immunohistochemical analysis of normal breast tissue revealed robust elafin expression in the mammary epithelium; however, elafin expression was dramatically downregulated in a significant proportion of human breast tumor specimens. The loss of elafin expression during breast cancer progression may promote tumor growth as a consequence of increased NE-activity. To address the role of NE in mammary tumorigenesis, we next examined if deregulated NE-activity enhances mammary tumor growth. NE knockout in the C3(1)TAg mouse model of mammary tumorigenesis suppressed proliferation and reduced the kinetics of tumor growth. Overall, the imbalance between NE and its inhibitors, such as elafin, presents an important therapeutic target in breast cancer.