SIX1 coordinates with TGFβ signals to induce epithelial-mesenchymal transition in cervical cancer

Targeting sine oculis homeoprotein 1 (SIX1): A review of oncogenic roles and potential natural product therapeutics

Sine oculis homeoprotein 1 (SIX1), a prominent representative of the homeodomain transcription factors within the SIX family, has attracted significant interest owing to its role in tumorigenesis, cancer progression, and prognostic assessments. Initially recognized for its pivotal role in embryonic development, SIX1 has emerged as a resurgent factor across a diverse set of mammalian cancers. Over the past two decades, numerous investigations have emphasized SIX1's dual significance as a developmental regulator and central player in oncogenic processes. A mounting body of evidence links SIX1 to the initiation of diverse cancers, encompassing enhanced cellular metabolism and advancement. This review provides an overview of the multifaceted roles of SIX1 in both normal development and oncogenic processes, emphasizing its importance as a possible therapeutic target and prognostic marker. Additionally, this review discusses the natural product agents that inhibit various pro-oncogenic mechanisms associated with SIX1.

Retinal determination gene networks: from biological functions to therapeutic strategies

The retinal determinant gene network (RDGN), originally discovered as a critical determinator in Drosophila eye specification, has become an important regulatory network in tumorigenesis and progression, as well as organogenesis. This network is not only associated with malignant biological behaviors of tumors, such as proliferation, and invasion, but also regulates the development of multiple mammalian organs. Three members of this conservative network have been extensively investigated, including DACH, SIX, and EYA. Dysregulated RDGN signaling is associated with the initiation and progression of tumors. In recent years, it has been found that the members of this network can be used as prognostic markers for cancer patients. Moreover, they are considered to be potential therapeutic targets for cancer. Here, we summarize the research progress of RDGN members from biological functions to signaling transduction, especially emphasizing their effects on tumors. Additionally, we discuss the roles of RDGN members in the development of organs and tissue as well as their correlations with the pathogenesis of chronic kidney disease and coronary heart disease. By summarizing the roles of RDGN members in human diseases, we hope to promote future investigations into RDGN and provide potential therapeutic strategies for patients.

The Role of Cytokines in Epithelial-Mesenchymal Transition in Gynaecological Cancers: A Systematic Review

Chronic inflammation has been closely linked to the development and progression of various cancers. The epithelial-mesenchymal transition (EMT) is a process involving the acquisition of mesenchymal features by carcinoma cells and is an important link between inflammation and cancer development. Inflammatory mediators in the tumour micro-environment, such as cytokines and chemokines, can promote EMT changes in cancer cells. The aim of this systematic review is to analyse the effect of cytokines on EMT in gynaecological cancers and discuss their possible therapeutic implications. A search of the databases CINAHL, Cochrane, Embase, Medline, PubMed, TRIP, and Web of Science was performed using the keywords: "cytokines" AND "epithelial mesenchymal transition OR transformation" AND "gynaecological cancer". Seventy-one articles reported that various cytokines, such as TGF-β, TNF-α, IL-6, etc., promoted EMT changes in ovarian, cervical, and endometrial cancers. The EMT changes included from epithelial to mesenchymal morphological change, downregulation of the epithelial markers E-cadherin/β-catenin, upregulation of the mesenchymal markers N-cadherin/vimentin/fibronectin, and upregulation of the EMT-transformation factors (EMT-TF) SNAI1/SNAI2/TWIST/ZEB. Cytokine-induced EMT can lead to gynaecological cancer development and metastasis and hence novel therapies targeting the cytokines or their EMT signalling pathways could possibly prevent cancer progression, reduce cancer recurrence, and prevent drug-resistance.

Targeting key proteins involved in transcriptional regulation for cancer therapy: Current strategies and future prospective

The key proteins involved in transcriptional regulation play convergent roles in cellular homeostasis, and their dysfunction mediates aberrant gene expressions that underline the hallmarks of tumorigenesis. As tumor progression is dependent on such abnormal regulation of transcription, it is important to discover novel chemical entities as antitumor drugs that target key tumor-associated proteins involved in transcriptional regulation. Despite most key proteins (especially transcription factors) involved in transcriptional regulation are historically recognized as undruggable targets, multiple targeting approaches at diverse levels of transcriptional regulation, such as epigenetic intervention, inhibition of DNA-binding of transcriptional factors, and inhibition of the protein-protein interactions (PPIs), have been established in preclinically or clinically studies. In addition, several new approaches have recently been described, such as targeting proteasomal degradation and eliciting synthetic lethality. This review will emphasize on accentuating these developing therapeutic approaches and provide a thorough conspectus of the drug development to target key proteins involved in transcriptional regulation and their impact on future oncotherapy.

Epithelial Mesenchymal Transition and its transcription factors

Epithelial–mesenchymal transition or EMT is an extremely dynamic process involved in conversion of epithelial cells into mesenchymal cells, stimulated by an ensemble of signaling pathways, leading to change in cellular morphology, suppression of epithelial characters and acquisition of properties such as enhanced cell motility and invasiveness, reduced cell death by apoptosis, resistance to chemotherapeutic drugs etc. Significantly, EMT has been found to play a crucial role during embryonic development, tissue fibrosis and would healing, as well as during cancer metastasis. Over the years, work from various laboratories have identified a rather large number of transcription factors (TFs) including the master regulators of EMT, with the ability to regulate the EMT process directly. In this review, we put together these EMT TFs and discussed their role in the process. We have also tried to focus on their mechanism of action, their interdependency, and the large regulatory network they form. Subsequently, it has become clear that the composition and structure of the transcriptional regulatory network behind EMT probably varies based upon various physiological and pathological contexts, or even in a cell/tissue type-dependent manner.

Systematical analysis reveals a strong cancer relevance of CREB1-regulated genes

The transcription factor cyclic-AMP response element-binding protein 1 (CREB1) responds to cAMP level and controls the expression of target genes, which regulates nutrition partitioning. The promoters of CREB1-targeted genes responsive to cAMP have been extensively investigated and characterized with the presence of both cAMP response element and TATA box. Compelling evidence demonstrates that CREB1 also plays an essential role in promoting tumor development. However, only very few genes required for cell survival, proliferation and migration are known to be constitutively regulated by CREB1 in tumors. Their promoters mostly do not harbor any cAMP response element. Thus, it is very likely that CREB1 regulates the expressions of distinct sets of target genes in normal tissues and tumors. The whole gene network constitutively regulated by CREB1 in tumors has remained unrevealed. Here, we employ a systematical and integrative approach to decipher this gene network in the context of both tissue cultured cancer cells and patient samples. We combine transcriptomic, Rank-Rank Hypergeometric Overlap, and Chipseq analysis, to define and characterize CREB1-regulated genes in a multidimensional fashion. A strong cancer relevance of those top-ranked targets, which meet the most stringent criteria, is eventually verified by overall survival analysis of cancer patients. These findings strongly suggest the importance of genes constitutively regulated by CREB1 for their implicative involvement in promoting tumorigenesis.

The SIX Family of Transcription Factors: Common Themes Integrating Developmental and Cancer Biology

The sine oculis (SIX) family of transcription factors are key regulators of developmental processes during embryogenesis. Members of this family control gene expression to promote self-renewal of progenitor cell populations and govern mechanisms of cell differentiation. When the function of SIX genes becomes disrupted, distinct congenital defects develops both in animal models and humans. In addition to the embryonic setting, members of the SIX family have been found to be critical regulators of tumorigenesis, promoting cell proliferation, epithelial-to-mesenchymal transition, and metastasis. Research in both the fields of developmental biology and cancer research have provided an extensive understanding of SIX family transcription factor functions. Here we review recent progress in elucidating the role of SIX family genes in congenital disease as well as in the promotion of cancer. Common themes arise when comparing SIX transcription factor function during embryonic and cancer development. We highlight the complementary nature of these two fields and how knowledge in one area can open new aspects of experimentation in the other.

Expression Of Cyclin D1 Protein Isoforms And Its Prognostic Significance In Cervical Cancer

Introduction

Cyclin D1 had been associated with different clinical and pathological stages of cervical cancer; however, few studies had focused on its correlation with cervical cancer prognosis. Therefore, this study aimed to assess the expression of cyclin D1a and D1b in normal tissue, cervical cancer and cervical intraepithelial neoplasia and their effect on prognosis.

Methods

Expression of cyclin D1a and D1b was detected by immunohistochemical staining in 78 cases of primary cervical cancer, 40 cases of cervical intraepithelial neoplasia, and 40 cases of normal cervical tissue.

Results

No significant difference was observed in the expression of cyclin D1a between normal and cervical cancer tissues (P = 0.201); however, its expression was significantly higher in cervical cancer than in cervical intraepithelial neoplasia tissues (P = 0.000). Expression of cyclin D1b was higher in normal tissues than in cervical cancer tissues (P = 0.000). No significant difference was observed in the expression of cyclin D1a in cervical cancer tissues with respect to age, pathological type, clinical-stage, depth of tumor invasion, or presence of lymph node metastases (P = 0.111,0.119,0.539,0.084,0.539). COX survival analysis showed that lymph node metastasis might be an independent factor affecting postoperative recurrence (hazard risk [HR] = 0.240; 95% confidence interval [CI] = 0.968–30.156; P = 0.034).

Discussion

Cyclin D1a expression was associated with tumor tissue size and degree of differentiation. The expression of cyclin D1b in cervical cancer was associated with the presence of lymph node metastases. Cyclin D1a and D1b expression in cervical cancer tissue was significantly correlated. Cox survival analysis showed that the presence of lymph node metastases might serve as an independent factor affecting postoperative recurrence. The expression of cyclin D1a and D1b was not associated with cervical cancer prognosis.

Conclusion

Assessment of cyclin D1a and D1b expression in cervical cancer and cervical intraepithelial neoplasia revealed that cyclin D1 could not be used as a reference to assess cervical cancer patient prognosis.

REGγ potentiates TGF-β/Smad signal dependent epithelial-mesenchymal transition in thyroid cancer cells

Thyroid cancer is the most common endocrine cancer with an increasing incidence and mortality. Epithelial-mesenchymal transition (EMT) is a biological process contributing to tumor progression, metastasis, and the acquisition of chemotherapy resistance. The impact of the REGγ proteasome activator on EMT in human thyroid cancer cells and the molecular mechanism is still unclear. Here, we found silencing REGγ in thyroid cancer cells inhibited cell migration and invasion, with concurrent upregulation of E-cadherin and Smurf2 expression. Mechanistically, REGγ dependent regulation of Smurf2, an E3 ligase for Smad3, contributed to alteration of Zeb1/2, Snail, Slug, and Twist. Consistently, TGF-β mediated suppression of E-cadherin was attenuated in REGγ deficient cells, coupled with changes in cell morphology, migration and invasion. Furthermore, xenograft metastasis mouse model showed a reduced E-cadherin expression at both mRNA and protein levels, and decreased cell migration. Taken together, our findings provided an important evidence for the role of REGγ in tumor suppression, thereby implicating REGγ as a potential anti-cancer strategy in thyroid cancer therapy.

MicroRNA-362 Inhibits Cell Proliferation and Invasion by Directly Targeting SIX1 in Colorectal Cancer

PURPOSE

Colorectal cancer (CRC) is the third most common cancer in China and poses high morbidity and mortality. In recent years, increasing evidence has indicated that microRNAs played important functions in the occurrence and development of tumors. The purpose of this study was to identify the biological mechanisms of miR-362 in CRC.

MATERIALS AND METHODS

Quantitative real-time PCR was carried out to assess the expression of miR-362 and SIX1. The Kaplan-Meier method was employed to evaluate the 5-year overall survival of CRC patients. The proliferative and invasive abilities of CRC cells were assessed by MTT and transwell assays.

RESULTS

miR-362 was significantly decreased in CRC tissues and cell lines, compared to the normal tissues and normal cells. A significant connection was confirmed between the overall survival of 53 CRC patients and low expression of miR-362. Downregulation of miR-362 inhibited the proliferation and invasion through binding to the 3'-UTR of SIX1 mRNA in CRC. Additionally, we discovered that SIX1 was a direct target gene of miR-362 and that the expression of miR-362 had a negative connection with SIX1 expression in CRC. SIX1 could reverse partial functions in the proliferation and invasion in CRC cells.

CONCLUSION

miR-362 may be a prognostic marker in CRC and suppress CRC cell proliferation and invasion in part through targeting the 3'-UTR of SIX1 mRNA. The newly identified miR-362/SIX1 axis provides insight into the progression of CRC.

Sine oculis homeobox 1 promotes proliferation and migration of human colorectal cancer cells through activation of Wnt/β-catenin signaling

Sine oculis homeobox 1 (Six1) is a homeodomain transcription factor that is aberrantly expressed in a variety of human cancers, including colorectal cancer (CRC). Six1 has been reported to play a key role in the proliferation and migration of CRC cells but the underlying molecular mechanisms are still poorly characterized. In the present study, we found that Six1 overexpression promoted the proliferation and migration of CRC cells. Consistently, Six1 knockdown (KD) significantly inhibited proliferation and migration of CRC cells. In addition, we showed that Six1 promoted proliferation and migration of CRC cells through activation of Wnt/β‐catenin signaling, as evidenced by promotion of nuclear localization of β‐catenin. Silencing of β‐catenin expression with siRNA or inhibiting Wnt signaling with a specific inhibitor, xav939, significantly blocked Six1‐induced nuclear localization of β‐catenin and mitigated Six1‐promoted proliferation and migration of CRC cells. We further confirmed the involvement of β‐catenin in Six1‐promoted proliferation and migration of CRC cells by activation of Wnt signaling with lithium chloride (LiCl) in Six1 KD CRC cells and results showed that LiCl restores defective β‐catenin nuclear localization and proliferation and migration of CRC cells. Taken together, these results suggest that Six1 homeoprotein promotes the proliferation and migration of CRC cells by activating the Wnt/β‐catenin signaling pathway, and strategies targeting Six1 may be promising for the treatment of CRC.

Regulation of cancer stem cell properties by SIX1, a member of the PAX-SIX-EYA-DACH network

The PAX-SIX-EYA-DACH network (PSEDN) is a central developmental transcriptional regulatory network from Drosophila to humans. The PSEDN is comprised of four conserved protein families; including paired box (PAX), sine oculis (SIX), eyes absent (EYA), and dachshund (DACH). Aberrant expression of PSEDN members, particularly SIX1, has been observed in multiple human cancers, where SIX1 expression correlates with increased aggressiveness and poor prognosis. In conjunction with its transcriptional activator EYA, the SIX1 transcription factor increases cancer stem cell (CSC) numbers and induces epithelial-mesenchymal transition (EMT). SIX1 promotes multiple hallmarks and enabling characteristics of cancer via regulation of cell proliferation, senescence, apoptosis, genome stability, and energy metabolism. SIX1 also influences the tumor microenvironment, enhancing recruitment of tumor-associated macrophages and stimulating angiogenesis, to promote tumor development and progression. EYA proteins are multifunctional, possessing a transcriptional activation domain and tyrosine phosphatase activity, that each contributes to cancer stem cell properties. DACH proteins function as tumor suppressors in solid cancers, opposing the actions of SIX-EYA and reducing CSC prevalence. Multiple mechanisms can lead to increased SIX1 expression, including loss of SIX1-targeting tumor suppressor microRNAs (miRs), whose expression correlates inversely with SIX1 expression in cancer patient samples. In this review, we discuss the major mechanisms by which SIX1 confers CSC and EMT features and other important cancer cell characteristics. The roles of EYA and DACH in CSCs and cancer progression are briefly highlighted. Finally, we summarize the clinical significance of SIX1 in cancer to emphasize the potential therapeutic benefits of effective strategies to disrupt PSEDN protein interactions and functions.

Ezrin and E-cadherin expression profile in cervical cytology: a prognostic marker for tumor progression in cervical cancer

Background

Cervical cancer (CC) is the fourth cause of mortality by neoplasia in women worldwide. The use of immunomarkers is an alternative tool to complement currently used algorithms for detection of cancer, and to improve selection of therapeutic schemes. Aberrant expression of Ezrin and E-cadherin play an important role in tumor invasion. In this study we analyzed Ezrin and E-cadherin expression in liquid-based cervical cytology samples, and evaluated their potential use as prognostic immunomarkers.

Methods

Immunocytochemical staining of Ezrin and E-cadherin was performed in cervical samples of 125 patients. The cytological or histological diagnostic was performed by Papanicolaou staining or H&E staining, respectively. HPV genotyping was determined using INNO-LIPA Genotyping Extra kit and the HPV physical status by in situ hybridization. Ezrin expression in HaCaT, HeLa and SiHa cell lines was determined by immunocytochemistry, immunofluorescence and Western blot.

Results

High Ezrin expression was observed in cervical cancer samples (70%), samples with multiple infection by HR-HPV (43%), and samples with integrated viral genome (47%). High Ezrin expression was associated with degree of SIL, viral genotype and physical status. In contrast, low E-cadherin expression was found in cervical cancer samples (95%), samples with multiple infection by HR-HPV/LR-HPV (87%) and integrated viral genome (72%). Low E-cadherin expression was associated with degree of SIL and viral genotype. Interestingly, Ezrin nuclear staining was associated with degree of SIL and viral genotype. High Ezrin expression, high percent of nuclear Ezrin and low E-cadherin expression behaved as risk factors for progression to HSIL and cervical cancer.

Conclusions

Ezrin and E-cadherin expression profile in cervical cytology samples could be a potential prognostic marker, useful for identifying cervical lesions with a high-risk of progression to cervical cancer.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4243-7) contains supplementary material, which is available to authorized users.

miR-202 inhibits the progression of human cervical cancer through inhibition of cyclin D1

The human cervical cancer (CC) acts as the most common one of women tumors. However, the pathological changes and molecular alterations of CC are not clear. It has been reported that miR-202 takes part in the development and progression of different tumors. The present study aims to detect the expression of miR-202 in 100 cases of CC tissues and cells, and then we continued to investigate the potential mechanisms of miR-202 in CC cells. In this work, we found that the expression of miR-202 is obviously decreased in both CC cell lines and tissues, and negatively related with the expression of cyclin D1 in SiHa, HeLa and Caski cells. In-vitro assay revealed that the ectopic expression of miR-202 suppressed the proliferation, migration and invasion of SiHa and HeLa cells. Additionally, the over-expression of miR-202 extremely affected the expression of cyclin D1 protein. Notably, the over-expression of cyclin D1 in SiHa and HeLa cells with miR-202 mimics attenuated the inhibitory effects of miR-202 on cell proliferation, migration and invasion. In conclusion, our study identified that miR-202 plays an important role in regulating cell proliferation, migration and invasion of CC by directly targeting cyclin D1, thus miR-202 may represent a potential therapeutic target for patients with cervical cancer.

Human thymic stromal lymphopoietin promotes the proliferation and invasion of cervical cancer cells by downregulating microRNA-132 expression

Thymic stromal lymphopoietin (TSLP), produced by cervical cancer (CC) cells, promotes angiogenesis, and the recruitment and functional regulation of eosinophils. It has been reported that microRNA (miR)-132 is aberrantly decreased in CC tissues. However, the function and mechanism of TSLP on the biological behaviors of CC cells is largely unknown. The aim of the present study was to investigate the effect of TSLP on the expression of miR-132 and the proliferation and invasion in vitro of CC cell lines, namely, HeLa and SiHa cells. The transcrpitional level of miR-132 was analyzed using reverse transcription-quantitative polymerase chaon reaction. The proliferation, invasion, and the expression of proliferation and invasion-related molecules in HeLa and SiHa cells in vitro were evaluated using bromodeoxyuridine cell proliferation, Matrigel invasion assays, flow cytometry and ELISA, respectively. Here, it was revealed that recombinant human TSLP (rhTSLP) downregulated the expression levels of miR-132 in HeLa and SiHa cells, and by contrast, the neutralizing antibodies for TSLP or TSLP receptor (TSLPR) upregulated miR-132 expression levels in HeLa and SiHa cells. The overexpression of miR-132 resulted in a lowered proliferation and invasiveness, decreased levels of proliferation-associated molecules marker of proliferation Ki-67 and proliferating cell nuclear antigen, and the decreased production of matrix metalloproteinase (MMP)2 and MMP9 in HeLa and SiHa cells. Compared with the control group, there was a higher level of proliferation and invasion in HeLa and SiHa cells following stimulation with rhTSLP. However, these effects induced by rhTSLP were significantly impaired in HeLa and SiHa cells with miR-132 overexpression. The results of the present study indicated that TSLP produced by CC cells downregulated miR-132 expression, and stimulated the proliferation and invasion of CC cells, thereby further promoting the development of CC.

MiR-205 serves as a prognostic factor and suppresses proliferation and invasion by targeting insulin-like growth factor receptor 1 in human cervical cancer

MicroRNAs are a kind of small and non-coding RNAs, which have been demonstrated to play an important role in the progression of human cervical cancer. Here, we found that the expression of miR-205 was low in cervical cancer cell lines and tissues, compared with matched non-tumor tissues and human endocervical epithelial cells. Also, miR-205 was inversely correlated with histological differentiation, metastasis, International Federation of Gynecology and Obstetrics stage, and the expression of insulin-like growth factor receptor 1 messenger RNA and protein. Besides, miR-205 or insulin-like growth factor receptor 1 expression is an independent prognostic factor. Mechanically, ectopic expression of miR-205 decreased proliferation, colony formation, and some proliferation/apoptosis-related proteins in cervical cancer cells. Ectopic expression of miR-205 caused G1 arrest. Luciferase reporter assays confirmed that binding of miR-205 to the 3' untranslated region of insulin-like growth factor receptor 1 may potentially decrease the expression of insulin-like growth factor receptor 1. Notably, insulin-like growth factor receptor 1 overexpression attenuated the inhibitory effects of miR-205 on cell proliferation and invasion, while small interfering RNA-insulin-like growth factor receptor 1 enhanced the inhibitory effects of miR-205 on cell proliferation and invasion. In conclusion, our findings suggested that miR-205 serves as a prognostic factor and suppresses proliferation and invasion by targeting insulin-like growth factor receptor 1 in human cervical cancer. Thus, miR-205/insulin-like growth factor receptor 1 pathway may be of great benefit to cervical cancer patients.

Switching Roles of TGF-β in Cancer Development: Implications for Therapeutic Target and Biomarker Studies

TGF-β induces complicated and even opposite responses in numerous biological processes, e.g., tumor suppression in pre-malignant cells and metastasis promotion in cancer cells. However, the cellular contextual determinants of these different TGF-β roles remain elusive, and the driver genes triggering the determinants’ changes have not been identified. Recently, however, several findings have provided new insights on the contextual determinants of Smads in TGF-β’s biological processes. These novel switches and their effectors may serve as prognostic biomarkers and therapeutic targets of TGF-β-mediated cancer progression.

SIX1 is overexpressed in endometrial carcinoma and promotes the malignant behavior of cancer cells through ERK and AKT signaling

The sineoculis homeobox homolog 1 (SIX1) protein has been found to be important for cancer progression. However, its biological role in human endometrial carcinomas remains unexplored. The potential mechanism of SIX1-induced cancer progression remains unclear. In the present study, SIX1 protein expression was examined in 84 cases of endometrial carcinoma tissues using immunohistochemisty, and SIX1 was found to be overexpressed in 51.1% (43/84) of cervical cancer cells. Small interfering RNA (siRNA) knockdown of SIX1 was also performed in Ishikawa cells with high endogenous SIX1 expression, and SIX1 was overexpressed in the HEC1B cell line with low endogenous expression. SIX1 overexpression promoted cell growth rate and colony formation ability, whereas SIX1 depletion inhibited cell growth and colony formation. Further analysis showed that SIX1 knockdown downregulated, and SIX1 overexpression upregulated, cyclin D1, cyclin E, phosphorylated (p-)extracellular signal-regulated kinase (ERK), and p-protein kinase B (AKT) expression. The ERK inhibitor, U0126, and AKT inhibitor treatments blocked the effect of SIX1 on proliferation. In conclusion, the present study found that SIX1 overexpression promotes cancer cell growth in endometrial carcinoma, possibly through ERK- and AKT-mediated pathways.