Sohlh2 inhibits breast cancer cell proliferation by suppressing Wnt/β‐catenin signaling pathway

Transcription Factor 21: A Transcription Factor That Plays an Important Role in Cardiovascular Disease

BACKGROUND

According to the World Health Organisation's Health Report 2019, approximately 17.18 million people die from cardiovascular disease each year, accounting for more than 30% of all global deaths. Therefore, the occurrence of cardiovascular disease is still a global concern. The transcription factor 21 (TCF21) plays an important role in cardiovascular diseases. This article reviews the regulation mechanism of TCF21 expression and activity and focuses on its important role in atherosclerosis in order to contribute to the development of diagnosis and treatment of cardiovascular diseases.

SUMMARY

TCF21 is involved in the phenotypic regulation of vascular smooth muscle cells (VSMCs), promotes the proliferation and migration of VSMCs, and participates in the activation of inflammatory sequences. Increased proliferation and migration of VSMCs can lead to neointimal hyperplasia after vascular injury. Abnormal hyperplasia of neointima and inflammation are one of the main features of atherosclerosis. Therefore, targeting TCF21 may become a potential treatment for relieving atherosclerosis.

KEY MESSAGES

TCF21 as a member of basic helix-loop-helix transcription factors regulates cell growth and differentiation by modulating gene expression during the development of different organs and plays an important role in cardiovascular development and disease. VSMCs and cells derived from VSMCs constitute the majority of plaques in atherosclerosis. TCF21 plays a key role in regulation of VSMCs' phenotype, thus accelerating atherogenesis in the early stage. However, TCF21 enhances plaque stability in late-stage atherosclerosis. The dual role of TCF21 should be considered in the translational medicine.

Sohlh2 promotes pulmonary fibrosis via repression of p62/Keap1/Nrf2 mediated anti-oxidative signaling pathway

Disturbance in the redox balance of alveolar epithelial cells (AECs) was considered as a causal factor for pulmonary fibrosis. The regulatory mechanisms of redox hemostasis in the development of pulmonary fibrosis remain largely unknown. Using a type II AEC-specific Sohlh2 conditional knock-in (CKI) mouse model, we found that Sohlh2, a basic HLH transcription factor, accelerated age-related pulmonary fibrosis. High-fat diet (HFD) resulted in a tremendous increase in lung inflammation and fibrotic changes in the lung tissues of Sohlh2 CKI mice. Sohlh2 overexpression led to a significant rise of intracellular ROS and apoptosis in the lung, mouse primary AECIIs, and human A549 cells, which was attenuated by ROS inhibitor (NAC). Sohlh2 enhanced oxidative stress via repressing p62/Keap1/Nrf2 mediated anti-oxidative signaling pathway. p62, a direct target of Sohlh2, mediated Sohlh2 effects on ROS generation and apoptosis in A549 cells. Hence, our findings elucidate a pivotal mechanism underlying oxidative stress-induced pulmonary fibrosis, providing a framework for aging-related disorder interventions.

Biological functions and molecular interactions of Wnt/β-catenin in breast cancer: Revisiting signaling networks

Changes in lifestyle such as physical activity and eating habits have been one of the main reasons for development of various diseases in modern world, especially cancer. However, role of genetic factors in initiation of cancer cannot be ignored and Wnt/β-catenin signaling is such factor that can affect tumor progression. Breast tumor is the most malignant tumor in females and it causes high mortality and morbidity around the world. The survival and prognosis of patients are not still desirable, although there have been advances in introducing new kinds of therapies and diagnosis. The present review provides an update of Wnt/β-catenin function in breast cancer malignancy. The upregulation of Wnt is commonly observed during progression of breast tumor and confirms that tumor cells are dependent on this pathway Wnt/β-catenin induction prevents apoptosis that is of importance for mediating drug resistance. Furthermore, Wnt/β-catenin signaling induces DNA damage repair in ameliorating radio-resistance. Wnt/β-catenin enhances proliferation and metastasis of breast tumor. Wnt/β-catenin induces EMT and elevates MMP expression. Furthermore, Wnt/β-catenin participates in tumor microenvironment remodeling and due to its tumor-promoting factor, drugs for its suppression have been developed. Different kinds of upstream mediators Wnt/β-catenin signaling in breast cancer have been recognized that their targeting is a therapeutic approach. Finally, Wnt/β-catenin can be considered as a biomarker in clinical trials.

MESP2 binds competitively to TCF4 to suppress gastric cancer progression by regulating the SKP2/p27 axis

Gastric cancer (GC) is a major cause of human deaths worldwide, and is notorious for its high incidence and mortality rates. Mesoderm Posterior Basic Helix-loop-helix (bHLH) transcription factor 2 (MESP2) acts as a transcription factor with a conserved bHLH domain. However, whether MESP2 contributes to tumorigenesis and its potential molecular mechanisms, remain unexplored. Noticeably, MESP2 expression levels are decreased in GC tissues and cell lines compared to those in normal tissue. Further, in vitro and in vivo experiments have confirmed that MESP2 overexpression suppresses GC cell growth, migration, and invasion, whereas MESP2 knockdown results in the exact opposite. Here, we present the first report that MESP2 binds to transcription factor 7-like 2 (TCF7L2/TCF4) to inhibit the activation of the TCF4/beta-catenin transcriptional complex, decrease the occupancy of the complex on the S-phase kinase Associated Protein 2 (SKP2) promoter, and promote p27 accumulation. MESP2 knockdown facilitated tumorigenesis, which was partially suppressed by SKP2 knockdown. Taken together, we conclude that MESP2 binds competitively to TCF4 to suppress GC progression by regulating the SKP2/p27 axis, thus offering a potential therapeutic strategy for future treatment.

Sohlh2 Regulates the Stemness and Differentiation of Colon Cancer Stem Cells by Downregulating LncRNA-H19 Transcription

Colon cancer stem cells (CSC) are tumor-initiating cells that drive tumorigenesis and progression through self-renewal and various differentiation potency. Therefore, the identification of factors critical for colon CSC function is vital for the development of therapies. Sohlh2 belongs to the superfamily of bhlh transcription factors and serves as a tumor suppressor in several tumors. The role of Sohlh2 in CSCs remains unknown. Here we demonstrated that Sohlh2 was related to the inhibition of LncRNA-H19/miR-141/β-catenin signaling and led to the consequent suppression of colon CSC stemness and the promotion of colon CSC differentiation in vitro and in vivo. Moreover, Sohlh2 could directly bind to the promoter of LncRNA-H19 and repress its transcription activity. LncRNA-H19 mediated the effects of Sohlh2 on colon CSC stemness and differentiation. Clinically, we observed a significant inverse correlation between Sohlh2 and LncRNA-H19, β-catenin, Lgr5, CD133 expression levels, and positive correlation between Sohlh2 and MUC2, TFF2 expression in colon cancer tissues. Collectively, our findings suggest an important role of the Sohlh2/LncRNA-H19/miR-141/β-catenin pathway in regulating colon CSC stemness and differentiation, suggesting potential therapeutic targets for colon cancer.

IMPLICATIONS

This study identifies that Sohlh2 directly manipulates LncRNA-H19 transcription and suppresses the β-catenin signaling pathway and the Sohlh2/LncRNA-H19/miR-141/β-catenin signaling pathway plays an essential role in the stemness of colon CSCs.

Identification of a Five-Gene Panel to Assess Prognosis for Gastric Cancer

Methods

Two datasets were used as training and validation cohorts to establish the predictive model. We used three types of screening criteria: background analysis, pathway analysis, and functional analysis provided by the cBioportal website. Fisher's exact test and multivariable logistic regression were performed to screen out related genes. Furthermore, we performed receiver operating characteristic (ROC) and Kaplan–Meier curve analyses to evaluate the correlation between the selected genes and overall survival.

Result

We screened five genes (KNL1, NRXN1, C6, CCDC169-SOHLH2, and TTN) that were highly related to recurrence of GC. The area under the receiver operating characteristic (ROC) curve was 0.813, which was much higher than that of the baseline model (AUC = 0.699). This result suggested that the mutation of five selected genes had a significant effect on the prediction of recurrence compared with other factors (age, stages, history, etc.). Furthermore, the Kaplan-Meier estimator also revealed that the mutation of five genes positively correlated with patient survival.

Conclusions

The patients who have mutations in these five genes may experience longer survival than those who do not have mutations. This five-gene panel will likely be a practical tool for prognostic evaluation and will provide another possible way for clinicians to determine therapy.

Sohlh2 Inhibits the Malignant Progression of Renal Cell Carcinoma by Upregulating Klotho via DNMT3a

Background

Renal cell carcinoma is the most common malignant tumor of the kidney. The 5-year survival of renal cell carcinoma with distant metastasis is very low. Sohlh2 is a newly discovered tumor suppressor gene playing inhibitory roles in a variety of tumors, but its role in renal cell carcinoma has not been reported.

Methods

To clarify the role of Sohlh2 in the occurrence and development of renal cell carcinoma, we constructed stably transfected human renal cell carcinoma cell lines with Sohlh2 overexpression and Sohlh2 knockdown, separately. First, we studied the effects of Sohlh2 on proliferation, migration, invasion, and epithelial–mesenchymal transition (EMT) of renal cell carcinoma cells in vitro and in vivo. Then, we detected whether Sohlh2 functions through DNMT3a/Klotho using Western blotting, qPCR, and Cell Counting Kit-8 (CCK-8) assay. Finally, we collected 40 resected renal cell carcinoma samples to study the relevance between Sohlh2, DNMT3a, and Klotho by immunohistochemistry.

Results

Our results showed that Sohlh2 was downregulated in renal cell carcinoma, and its expression level was negatively correlated with tumor staging. Both in vitro and in vivo experiments confirmed that Sohlh2 overexpression inhibited the proliferation, migration, invasion, metastasis, and EMT of renal cell carcinoma. Sohlh2 functions through demethylation of Klotho by downregulating the expression of DNA methyltransferase of DNMT3a. In renal cell carcinoma, Sohlh2 was positively correlated with Klotho and negatively correlated with DNMT3a.

Conclusion

Sohlh2 functions as a tumor suppressor gene in renal cell carcinoma by demethylation of Klotho via DNMT3a. Sohlh2 correlated with Klotho positively and with DNMT3a negatively in renal cell carcinoma. Our study suggests that Sohlh2 and DNMT3a/Klotho can be used as potential targets for the clinical treatment of renal cell carcinoma.

The Wnt/β-catenin pathway in breast cancer therapy: a pre-clinical perspective of its targeting for clinical translation

INTRODUCTION

Despite various treatments available, there is still a high mortality rate in breast cancer patients. Thus, there exists an unmet need for new therapeutic interventions. Studies show that the Wnt/β-catenin signaling pathway is involved in breast cancer metastasis because of its transcriptional control on epithelial to mesenchymal transition.

AREAS COVERED

This comprehensive review explores the Wnt signaling pathway as a potential target for treating breast cancer and other breast cancer subtypes. We discuss the Wnt signaling pathway, its role in breast cancer metastasis, and its effect on breast cancer stem cells. Further, endogenous agents that cause Wnt pathway inactivation are outlined. Finally, various natural and chemical compounds modulating the Wnt pathway used in pre-clinical or clinical trials for breast cancer treatment are discussed.

EXPERT OPINION

In vitro and in vivo studies indicate an immense potential of agents targeting the Wnt signaling pathway to prevent and manage breast cancer. Still, more clinical studies are required to support their use in humans. Apart from the agents already in clinical trials, several drug combinations discussed may be translated into clinical practice in a few years.

Circ-DONSON Knockdown Inhibits Cell Proliferation and Radioresistance of Breast Cancer Cells via Regulating SOX4

Background

Circular RNAs have been validated as critical regulators in the development of breast cancer (BC). Circ-DONSON is involved in the progression of glioma and gastric cancer. However, the biological role of circ-DONSON in BC remains unclear, and the aim of this study was to explore the biological role of circ-DONSON in BC.

Methods

Human tissue samples and BC cell lines were collected in this study. siRNAs against circ-DONSON were transfected into BC cell lines for silencing of circ-DONSON. Quantitative real-time PCR was used to test the circ-DONSON expression. Cell counting kit-8 (CCK-8), 5-bromo-2' deoxyuridine enzyme-linked immunosorbent assay (BrdU-ELISA), colony formation, and caspase-3 activity assays were used to assess cell proliferation, cell survival, and cell viability. Western blotting analysis was used to detect the protein expression levels.

Results

Our findings showed that circ-DONSON showed high expression in BC tissues and cell lines. CCK-8 and BrdU-ELISA assays showed that circ-DONSON knockdown inhibited BC cell proliferation. Moreover, cell survival, cell viability, and caspase-3 activity assays showed that circ-DONSON knockdown reduced the radioresistance of BC cells. Mechanistically, circ-DONSON regulated BC cell proliferation and radioresistance via SRY-box transcription factor 4 (SOX4). SOX4 overexpression significantly rescued the effect of circ-DONSON knockdown on BC cell proliferation and radioresistance. Moreover, circ-DONSON activated the Wnt/β-catenin pathway in BC cells via SOX4.

Conclusion

Our study concluded that circ-DONSON knockdown hindered cell proliferation and radioresistance through the SOX4/Wnt/β-catenin pathway in BC.

SOHLH2 Suppresses Angiogenesis by Downregulating HIF1α Expression in Breast Cancer

SOHLH2 has been demonstrated the downregulation in various cancers and the involvement in tumor growth and metastasis. However, the function of SOHLH2 on tumor angiogenesis and the underlying molecular mechanisms have not been interrogated. IHC staining results revealed that SOHLH2 was negatively associated with microvessel density (MVD), tumor size, histology grade, and metastasis. Overexpression of SOHLH2 inhibited the angiogenic behavior of human umbilical vein endothelial cells (HUVEC) by a tumor cell-mediated paracrine signal, while knockdown of SOHLH2 promoted HUVEC angiogenic behavior. Ectopic SOHLH2 expression remarkably suppressed tumor growth and MVD in xenograft tumors, downregulated the expression of hypoxia inducible factor-1 alpha (HIF1α)-mediated proangiogenic genes in vivo and in vitro, while knockdown of SOHLH2 had an opposite result. Furthermore, we found that upregulation of HIF1α reversed SOHLH2-induced suppression of breast cancer angiogenesis, while KC7F2, the inhibitor of HIF1α, could attenuate the promotion of angiogenesis by SOHLH2 silencing. Using Chromatin immunoprecipitation and luciferase reporter assays, we validated that SOHLH2 could directly bind to HIF1α promoter and repress its transcriptional activity. Collectively, SOHLH2 suppresses breast cancer angiogenesis by downregulating HIF1α transcription and may be a potential biomarker for anti-angiogenesis therapy. IMPLICATIONS: SOHLH2 directly represses HIF1α-mediated angiogenesis and serves as an important inhibitor of angiogenesis in breast cancer.

Diallyl trisulfide potentiates chemotherapeutic efficacy of doxorubicin in experimentally induced mammary carcinoma: Role of Notch signaling

The prevalence of breast cancer is remarkably increasing worldwide. Therefore, introduction of new approaches along with improvement of the existing ones in cancer treatment field is of great demand. The present study was designated to investigate the anti-proliferative role of Diallyl trisulfide (DATS) alone or in combination with Doxorubicin (Doxo) in Ehrlich solid carcinoma (ESC)-bearing mice. ESC was induced in female albino mice as an experimental model for breast cancer. The anti-tumorigenic effect of DATS was mediated by suppression of Notch signaling proteins (Notch 1, JAG 1 and HES 1), attenuation of tumor inflammation (NFκB, TNF-α, IL-6, IL-1β) and proliferation (cyclin D1, Ki67) and enhancement of apoptosis (caspase 3, p53). DATS and Doxo mono-treatments displayed opposing effect regarding expression of Notch signaling proteins and cyclin D1 gene expression. However, DATS and Doxo co-treatment markedly decreased tumor volume and weight, increased animals' survival rate, and attenuated Doxo-induced tumor inflammation. In parallel, microscopic investigation displayed that ESC tumor tissues from animals treated with DATS and/or DOX showed shrinkage of tumor lesions and wider zones of apoptosis. In conclusion, DATS acts via multiple molecular targets to elicit anti-proliferative activity. Combination of DATS with Doxo -which exhibit different mechanisms of action- might be a potential novel strategy to augment Doxo-antitumor effect.

Effect of endostatin on Wnt pathway of stem-like cells in bladder cancer in tumor microenvironment

Wnt/β-catenin signaling pathway modulates miscellaneous biological events in cells including gene expression, cell growth, apoptosis, metabolism and transition. The aim of this study was to investigate the effect of endostatin on Wnt signaling pathway of stem-like cells in bladder cancer in tumor microenvironment. The qRT-PCR assay and western blot were conducted to evaluate related factors expressions of Wnt signaling pathway in both bladder cancer 5637 cells and stem cells. Loss of function assays were carried out to detect the influence of endostatin on the proliferation, migration, cell proliferation and apoptosis of bladder cancer cells. We demonstrated that endostatin triggered the degradation of β-catenin, a key mediator of Wnt signaling. The activation of the endostatin blocked β-catenin function and inhibited cell growth and migration of bladder cancer. In order to verify that the Wnt/β-catenin signaling pathway was inhibited by endostain in 5637 bladder cancer cells and stem cells, the Wnt/β-catenin signaling pathway-associated molecules, including DKK1, LRP5, TCF4, β-catenin, cyclin D1, and c-Myc, were evaluated in 5637 bladder cancer cells and stem cells. The western blotting results showed that expressions of these molecules were remarkably increased in the 5637 bladder cancer cells and stem cells compared to the control group. In summary, our study demonstrated that endostatin inhibited angiogenesis. The downregulation of the Wnt/β-catenin pathway may be engaged in the suppression of angiogenesis by endostatin in bladder cancer cells and cancer stem cells.

Effects of cisplatin on the proliferation, invasion and apoptosis of breast cancer cells following β‑catenin silencing

Resistance to the chemotherapeutic drug cisplatin has been documented in various types of cancer, while the increased expression of β-catenin has been observed in cisplatin-resistant ovarian cancer. However, the involvement of β-catenin in cisplatin resistance is unclear. The present study investigated the antitumor effect of cisplatin on the proliferation, invasion and apoptosis of breast cancer (BC) cells following β-catenin silencing in BC, which is the most frequent type of malignancy among women. The expression of β-catenin in BC tissues and cell lines was measured by reverse transcription-quantitative polymerase chain reaction, and the association between expression levels and clinical characteristics was statistically analyzed. The viability of BC cell lines treated with siR-β-catenin or with siR-β-catenin and cisplatin in combination was determined using a Cell Counting Kit-8 assay. The migratory and invasive abilities of BC cells treated with both siR-β-catenin and cisplatin were examined with Transwell assays. The CD44 antigen/intercellular adhesion molecule 1 expression ratio, cell cycle distribution and apoptosis levels of BC cells treated with siR-β-catenin and cisplatin in combination were detected by flow cytometry. The expression levels of apoptosis-associated proteins, including caspase-3/9, in the BC cells treated with both siR-β-catenin and cisplatin were investigated by western blot analysis. The levels of apoptosis in the BC cells following combined treatment with siR-β-catenin and cisplatin was further quantified by Hoechst 33342 staining. β-catenin was identified to be highly expressed in BC tissues and cell lines and was associated with pathological stage and lymph node status. Following knockdown of β-catenin expression, cisplatin treatment suppressed the viabilities, and the migratory and invasive capabilities of the T47D and MCF-7 cells, and induced extensive apoptosis. β-catenin knockdown upregulated caspase-3/9 levels following cisplatin treatment and induced the apoptosis of T47D and MCF-7 cells. In conclusion, β-catenin may be of value as a therapeutic target during cisplatin treatment in patients with BC treated with cisplatin.