ZEB1 stimulates breast cancer growth by up-regulating hTERT expression

Metastasis and chemoresistance in breast cancer: Crucial function of ZEB1/2 proteins

Breast cancer remains one of the leading causes of mortality worldwide. While advancements in chemotherapy, immunotherapy, radiotherapy, and targeted therapies have significantly improved breast cancer treatment, many patients are diagnosed at advanced stages, where tumor cells exhibit aggressive behavior and therapy resistance. Understanding the mechanisms driving breast cancer progression is therefore critical. Metastasis is a major factor that drastically reduces patient prognosis and survival, accounting for most breast cancer-related deaths. ZEB proteins have emerged as key regulators of cancer metastasis. Beyond their role in metastasis, ZEB proteins also influence drug resistance. This review focuses on the role of ZEB1 and ZEB2 in regulating breast cancer metastasis. These proteins interact with components of the tumor microenvironment (TME) to drive cancer progression and metastasis. Additionally, ZEB proteins regulate angiogenesis through interactions with VEGF. Targeting ZEB proteins offers potential therapeutic benefits, particularly for aggressive breast cancer subtypes such as triple-negative breast cancer (TNBC), which often show poor therapeutic response. ZEB proteins also influence the sensitivity of breast cancer cells to chemotherapy, making them promising targets for enhancing treatment efficacy. Given their upregulation in breast cancer, ZEB proteins can serve as valuable diagnostic and prognostic markers.

Obesity-Senescence-Breast Cancer: Clinical Presentation of a Common Unfortunate Cycle

There are few convincing studies establishing the relationship between endogenous factors that cause obesity, cellular aging, and telomere shortening. Without a functional telomerase, a cell undergoing cell division has progressive telomere shortening. While obesity influences health and longevity as well as telomere dynamics, cellular senescence is one of the major drivers of the aging process and of age-related disorders. Oxidative stress induces telomere shortening, while decreasing telomerase activity. When progressive shortening of telomere length reaches a critical point, it triggers cell cycle arrest leading to senescence or apoptotic cell death. Telomerase activity cannot be detected in normal breast tissue. By contrast, maintenance of telomere length as a function of human telomerase is crucial for the survival of breast cancer cells and invasion. Approximately three-quarters of breast cancers in the general population are hormone-dependent and overexpression of estrogen receptors is crucial for their continued growth. In obesity, increasing leptin levels enhance aromatase messenger ribonucleic acid (mRNA) expression, aromatase content, and its enzymatic activity on breast cancer cells, simultaneously activating telomerase in a dose-dependent manner. Meanwhile, applied anti-estrogen therapy increases serum leptin levels and thus enhances leptin resistance in obese postmenopausal breast cancer patients. Many studies revealed that shorter telomeres of postmenopausal breast cancer have higher local recurrence rates and higher tumor grade. In this review, interlinked molecular mechanisms are looked over between the telomere length, lipotoxicity/glycolipotoxicity, and cellular senescence in the context of estrogen receptor alpha-positive (ERα+) postmenopausal breast cancers in obese women. Furthermore, the effect of the potential drugs, which are used for direct inhibition of telomerase and the inhibition of human telomerase reverse transcriptase (hTERT) or human telomerase RNA promoters as well as approved adjuvant endocrine therapies, the selective estrogen receptor modulator and selective estrogen receptor down-regulators are discussed.

Regulation and clinical potential of telomerase reverse transcriptase (TERT/hTERT) in breast cancer

Telomerase reverse transcriptase (TERT/hTERT) serves as the pivotal catalytic subunit of telomerase, a crucial enzyme responsible for telomere maintenance and human genome stability. The high activation of hTERT, observed in over 90% of tumors, plays a significant role in tumor initiation and progression. An in-depth exploration of hTERT activation mechanisms in cancer holds promise for advancing our understanding of the disease and developing more effective treatment strategies. In breast cancer, the expression of hTERT is regulated by epigenetic, transcriptional, post-translational modification mechanisms and DNA variation. Besides its canonical function in telomere maintenance, hTERT exerts non-canonical roles that contribute to disease progression through telomerase-independent mechanisms. This comprehensive review summarizes the regulatory mechanisms governing hTERT in breast cancer and elucidates the functional implications of its activation. Given the overexpression of hTERT in most breast cancer cells, the detection of hTERT and its associated molecules are potential for enhancing early screening and prognostic evaluation of breast cancer. Although still in its early stages, therapeutic approaches targeting hTERT and its regulatory molecules show promise as viable strategies for breast cancer treatment. These methods are also discussed in this paper. Video Abstract.

Zinc Finger E-Box Binding Homeobox Family: Non-Coding RNA and Epigenetic Regulation in Gliomas

Gliomas are the most common malignant brain tumours. Among them, glioblastoma (GBM) is a grade four tumour with a median survival of approximately 15 months and still limited treatment options. Although a classical epithelial to mesenchymal transition (EMT) is not the case in glioma due to its non-epithelial origin, the EMT-like processes may contribute largely to the aggressive and highly infiltrative nature of these tumours, thus promoting invasive phenotype and intracranial metastasis. To date, many well-known EMT transcription factors (EMT-TFs) have been described with clear, biological functions in glioma progression. Among them, EMT-related families of molecules such as SNAI, TWIST and ZEB are widely cited, well-established oncogenes considering both epithelial and non-epithelial tumours. In this review, we aimed to summarise the current knowledge with a regard to functional experiments considering the impact of miRNA and lncRNA as well as other epigenetic modifications, with a main focus on ZEB1 and ZEB2 in gliomas. Although we explored various molecular interactions and pathophysiological processes, such as cancer stem cell phenotype, hypoxia-induced EMT, tumour microenvironment and TMZ-resistant tumour cells, there is still a pressing need to elucidate the molecular mechanisms by which EMT-TFs are regulated in gliomas, which will enable researchers to uncover novel therapeutic targets as well as improve patients' diagnosis and prognostication.

The Relevance of Telomerase and Telomere-Associated Proteins in B-Acute Lymphoblastic Leukemia

Telomeres and telomerase are closely linked to uncontrolled cellular proliferation, immortalization and carcinogenesis. Telomerase has been largely studied in the context of cancer, including leukemias. Deregulation of human telomerase gene hTERT is a well-established step in leukemia development. B-acute lymphoblastic leukemia (B-ALL) recovery rates exceed 90% in children; however, the relapse rate is around 20% among treated patients, and 10% of these are still incurable. This review highlights the biological and clinical relevance of telomerase for B-ALL and the implications of its canonical and non-canonical action on signaling pathways in the context of disease and treatment. The physiological role of telomerase in lymphocytes makes the study of its biomarker potential a great challenge. Nevertheless, many works have demonstrated that high telomerase activity or hTERT expression, as well as short telomeres, correlate with poor prognosis in B-ALL. Telomerase and related proteins have been proven to be promising pharmacological targets. Likewise, combined therapy with telomerase inhibitors may turn out to be an alternative strategy for B-ALL.

ZNF276 promotes the malignant phenotype of breast carcinoma by activating the CYP1B1-mediated Wnt/β-catenin pathway

Zinc finger proteins (ZNFs) have been demonstrated to participate extensively in breast cancer progression by functioning as transcription factors, but there are still a variety of ZNFs whose biological mechanisms remain unknown. Here, we show that zinc finger protein 276 (ZNF276) is highly expressed in breast cancer tissues and cell lines. Higher level of ZNF276 correlated with poor prognosis. Gain-of and loss-of function suggested that ZNF276 is essential for the proliferation, migration and invasion of breast cancer cells in vitro and metastasis in vivo. RNA-sequencing and CUT&Tag assay revealed that ZNF276 controlled a variety of growth and metastasis-related genes expression. ZNF276 transcriptionally promoted the expression of CYP1B1 by directly binds to the promoter region of the CYP1B1 through its C₂H₂ domain. ZNF276 facilitated the translocation of β-catenin from cytoplasm to nucleus through CYP1B1, leading to the upregulation of cyclin D1 and c-Myc, and the activation of the Wnt/β-catenin pathway. Knockdown of CYP1B1 significantly blocked the ZNF276-mediated effects on cell proliferation, migration and invasion. Lastly, ZNF276 interacted with MAGEB2 which enhanced the binding of ZNF276 at the CYP1B1 promoter, promoted CYP1B1 expression and Wnt signaling activation. Collectively, these findings highlight the oncogenic role of ZNF276 on breast cancer cell proliferation and metastasis. Targeting ZNF276/MAGEB2 axis may serve as a potential therapeutic strategy for breast cancer patients.

EZH2 affects malignant progression and DNA damage repair of lung adenocarcinoma cells by regulating RAI2 expression

BACKGROUND

Lung adenocarcinoma (LUAD) is featured in high morbidity and mortality. Aberrant activation of the histone methyltransferase EZH2 has close association with cancer progression. This research aimed to deeply dive into the role and possible molecular mechanisms of EZH2 and its downstream genes in malignant progression and DNA damage repair of LUAD cells.

METHODS

Expression of EZH2 in LUAD cells was analyzed by qRT-PCR, and the effects of EZH2 on proliferation, and apoptosis of LUAD cells were examined by CCK-8, colony formation and flow cytometry assays. The downstream targets of EZH2 were predicted by bioinformatics analysis. Then, the targeting relationship between EZH2 and RAI2 was examined by CHIP and luciferase reporter assays. Rescue assay were used to further validate the effect of EZH2/RAI2 on the malignant progression of LUAD cells. The expression levels of EZH2, RAI2 and p53 were examined by Western blot.

RESULTS

Upregulation of EZH2 was identified in LUAD tissues and cells. RAI2 was a downstream target gene of EZH2, and the two were negatively correlated. Silencing EZH2 suppressed proliferation of LUAD cells, promoted expression of p53, cell cycle arrest and apoptosis. While silencing RAI2 could reverse the above-mentioned effects caused by EZH2 silencing.

CONCLUSION

These results demonstrated that EZH2 promoted malignant progression and DNA damage repair of LUAD cells by targeting and negatively regulating RAI2.

The expression level of chicken telomerase reverse transcriptase in tumors induced by ALV-J is positively correlated with methylation and mutation of its promoter region

Avian leukosis virus subgroup J (ALV-J) can cause neoplastic diseases in poultry and is still widely prevalent in China. Chicken telomerase reverse transcriptase (chTERT) is the core component of telomerase, which is closely related to the occurrence and development of tumors. Our previous studies showed that chTERT is overexpressed in ALV-J tumors, but the mechanism is still not completely clear. Therefore, this study aims to analyze the possible molecular mechanism of chTERT overexpression in ALV-J tumors from the perspective of DNA methylation and promoter mutation. Methylation sequencing of the chTERT amplicon showed that ALV-J replication promoted the methylation level of the chTERT promoter. And the methylation level of the chTERT promoter in ALV-J tumors was significantly higher than that in tumor-adjacent and normal tissues. Compared with the tumor-adjacent and normal tissues, the chTERT promoter in each ALV-J tumors tested had a mutation of -183 bp C > T, and 36.0% (9/25) of the tumors also had mutations of -184 bp T > C, -73 bp::GGCCC and -56 bp A > T in the chTERT promoter, which formed the binding sites for the transcription factors NFAT5, TFAP2A and ZEB1, respectively. The results of RT-qPCR and Western blotting showed that the occurrence of these mutations significantly increased the expression level of chTERT. In conclusion, this study demonstrated that the high expression of chTERT in ALV-J tumors is positively correlated with the level of hypermethylation and mutation in its promoter, which provides a new perspective for further research on the molecular mechanism of chTERT in ALV-J tumorigenesis.

Τelomerase inhibitors and activators in aging and cancer: A systematic review

The main aim of the present systematic review was to summarize the most frequently used telomerase regulators with an impact on aging and cancer that are referred to in in vitro and in vivo studies. For this purpose, a systematic review of the available literature on telomerase regulators referred to in articles from PubMed and Scopus libraries published from 2002 to 2021 and in accordance with PRISMA 2020 criteria, was conducted. Articles were included if they met the following criteria: They referred to telomerase modulators in aging and in cancer and were in vitro and/or in vivo studies, while studies that did not provide sufficient data or studies not written in English were excluded. In the present systematic review, 54 publications were included, of which 29 were full‑text published studies, 11 were full‑text reviews, 10 structure‑based design studies and 4 abstracts are reported in this review. Telomerase regulators were then categorized as synthetic direct telomerase inhibitors, synthetic indirect telomerase inhibitors, synthetic telomerase activators, natural direct telomerase activators, natural telomerase inhibitors and natural indirect telomerase activators, according to their origin and their activity. On the whole, as demonstrated herein, telomerase regulators appear to be promising treatment agents in various age‑related diseases. However, further in vivo and in vitro studies need to be performed in order to clarify the potentiality of telomerase as a therapeutic target.

Functional interaction between endothelin-1 and ZEB1/YAP signaling regulates cellular plasticity and metastasis in high-grade serous ovarian cancer

Background

Epithelial-to-mesenchymal transition (EMT) encompasses a highly dynamic and complex key process which leads to metastatic progression. In high-grade serous ovarian carcinoma (HG-SOC), endothelin-1 (ET-1)/endothelin A receptor (ET_AR) signaling promotes EMT driving tumor progression. However, the complex nature of intertwined regulatory circuits activated by ET-1 to trigger the metastatic process is not fully elucidated.

Methods

The capacity of ET-1 pathway to guide a critical transcriptional network that is instrumental for metastatic growth was identified in patient-derived HG-SOC cells and cell lines through immunoblotting, q-RT-PCR, co-immunoprecipitation, in situ proximity ligation, luciferase reporter, chromatin immunoprecipitation assays and publicly available databases. Functional assays in HG-SOC cells and HG-SOC xenografts served to test the inhibitory effects of ET-1 receptors (ET-1R) antagonist in vitro and in vivo.

Results

We demonstrated that ET-1/ET_AR axis promoted the direct physical ZEB1/YAP interaction by inducing their nuclear accumulation in HG-SOC cells. Moreover, ET-1 directed their engagement in a functional transcriptional complex with the potent oncogenic AP-1 factor JUN. This led to the aberrant activation of common target genes, including EDN1 (ET-1) gene, thereby creating a feed-forward loop that sustained a persistent ET-1/ZEB1 signaling activity. Notably, ET-1-induced Integrin-linked kinase (ILK) signaling mediated the activation of YAP/ZEB1 circuit driving cellular plasticity, invasion and EMT. Of therapeutic interest, treatment of HG-SOC cells with the FDA approved ET-1R antagonist macitentan, targeting YAP and ZEB1-driven signaling, suppressed metastasis in vivo in mice. High gene expression of ET_AR/ILK/YAP/AP-1/ZEB1 was a strong predictor of poor clinical outcome in serous ovarian cancer patients, indicating the translational relevance of this signature expression.

Conclusions

This study provides novel mechanistic insights of the ET-1R-driven mediators that support the ability of HG-SOC to acquire metastatic traits which include the cooperation of YAP and ZEB1 regulatory circuit paving the way for innovative treatment of metastatic ovarian cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02317-1.

Proteomic Analysis of Zeb1 Interactome in Breast Carcinoma Cells

Breast cancer is the most frequently diagnosed malignant neoplasm and the second leading cause of cancer death among women. Epithelial-to-mesenchymal Transition (EMT) plays a critical role in the organism development, providing cell migration and tissue formation. However, its erroneous activation in malignancies can serve as the basis for the dissemination of cancer cells and metastasis. The Zeb1 transcription factor, which regulates the EMT activation, has been shown to play an essential role in malignant transformation. This factor is involved in many signaling pathways that influence a wide range of cellular functions via interacting with many proteins that affect its transcriptional functions. Importantly, the interactome of Zeb1 depends on the cellular context. Here, using the inducible expression of Zeb1 in epithelial breast cancer cells, we identified a substantial list of novel potential Zeb1 interaction partners, including proteins involved in the formation of malignant neoplasms, such as ATP-dependent RNA helicase DDX17and a component of the NURD repressor complex, CTBP2. We confirmed the presence of the selected interactors by immunoblotting with specific antibodies. Further, we demonstrated that co-expression of Zeb1 and CTBP2 in breast cancer patients correlated with the poor survival prognosis, thus signifying the functionality of the Zeb1–CTBP2 interaction.

<PE-AT>Contributions of Yap and Taz dysfunction to breast cancer initiation, progression, and aging-related susceptibility

Yap and Taz are co-transcription factors that have been implicated in the development of many cancers. Here, we review the literature that analyzes the function of Yap/Taz in normal breast and breast cancer contexts. Our review of the literature suggests that that Yap and Taz are involved in breast cancer and Taz, in particular, is involved in the triple negative subtype. Nevertheless, the precise contexts in which Yap/Taz contribute to specific breast cancer phenotypes remains unclear. Indeed, Yap/Taz dysregulation acts differentially and in multiple epithelial cell types during early breast cancer progression. We propose Yap/Taz activation promotes breast cancer phenotypes in breast cancer precursor cells. Further, Yap dysregulation as a result of aging in breast tissue may result in microenvironments that increase the fitness of breast cancer precursor cells relative to the normal epithelia. <PE-FRONTEND>.

Investigating the Role of Telomere and Telomerase Associated Genes and Proteins in Endometrial Cancer

Endometrial cancer (EC) is the commonest gynaecological malignancy. Current prognostic markers are inadequate to accurately predict patient survival, necessitating novel prognostic markers, to improve treatment strategies. Telomerase has a unique role within the endometrium, whilst aberrant telomerase activity is a hallmark of many cancers. The aim of the current in silico study is to investigate the role of telomere and telomerase associated genes and proteins (TTAGPs) in EC to identify potential prognostic markers and therapeutic targets. Analysis of RNA-seq data from The Cancer Genome Atlas identified differentially expressed genes (DEGs) in EC (568 TTAGPs out of 3467) and ascertained DEGs associated with histological subtypes, higher grade endometrioid tumours and late stage EC. Functional analysis demonstrated that DEGs were predominantly involved in cell cycle regulation, while the survival analysis identified 69 DEGs associated with prognosis. The protein-protein interaction network constructed facilitated the identification of hub genes, enriched transcription factor binding sites and drugs that may target the network. Thus, our in silico methods distinguished many critical genes associated with telomere maintenance that were previously unknown to contribute to EC carcinogenesis and prognosis, including NOP56, WFS1, ANAPC4 and TUBB4A. Probing the prognostic and therapeutic utility of these novel TTAGP markers will form an exciting basis for future research.

Clinical Significance of ZNF711 in Human Breast Cancer

Purpose

To investigate the clinicopathologic and prognostic significance of the zinc-finger protein 711 (ZNF711) in breast cancer (BCa).

Materials and Methods

The relevance of ZNF711 in BCa was analyzed using bioinformatics. The expression of ZNF711 was detected by immunohistochemistry in paraffin blocks of BCa. To evaluate its clinical significance, the correlation between the expression of ZNF711 and BCa clinical indicators, including estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER-2), was analyzed. Finally, the Kaplan-Meier method was applied to explore the prognostic value of ZNF711.

Results

ZNF711 expression was decreased in BCa and was negatively correlated with ER expression (P < 0.05) and positively correlated with HER-2 expression (P < 0.01), but there was no significant correlation between ZNF711 and PR expression. ZNF711 expression was not correlated with age, tumor diameter, or lymph node metastasis; however, ZNF711 expression was correlated with staging in BCa. Survival analysis results showed that the ZNF711-positive group patients had a poorer prognosis compared with the ZNF711-negative group.

Conclusion

The expression of ZNF711 was deceased in BCa and closely related to ER and HER-2 expression. Therefore, ZNF711 could not only serve as a predictor of BCa with poor prognosis but also as a potential biomarker for targeted therapy.

JAK2 inhibition in JAK2V617F-bearing leukemia cells enriches CD34+ leukemic stem cells that are abolished by the telomerase inhibitor GRN163L

The activating-mutation of JAK2V617F drives the development of myeloproliferative neoplasms (MPNs). Several JAK2 inhibitors such as ruxolitinib and gandotinib (LY2784544) currently in clinical trials and, provide improvements in MPNs including myelofibrosis. However, JAK2 inhibitors are non-curative and murine experiments show that JAK2 inhibitors don't eradicate MPN stem cells and it is currently unclear how they escape. We thus determined the effect of the specific JAK2V617F inhibitor LY2784544 on leukemic stem (CD34⁺) cells (LSCs) using the JAK2V617F-bearing erythroleukemia cell line HEL. The LY2784544 treatment caused a transient proliferation inhibition and apoptosis of HEL cells, but a recovery occurred within a week. Thereafter, the continuous LY2784544 exposure induced the accumulation of CD34⁺ LSCs, and the CD34⁺ cells increased from 2% to >90% by week 9, which was accompanied by increased clonogenic potentials. LY2784544 was capable of stimulating CD34 expression even in CD34^- HEL cells, which indicated cellular de-differentiation. A significantly enhanced expression of the stem cell factor KLF4 was observed in LY2784544-treated HEL cells. Inhibiting KLF4 expression attenuated LY2784544-mediated accumulation of CD34⁺ LSCs. Moreover, the telomerase inhibitor GRN163L abolished the LY2784544-effect. JAK2 inhibitors thus cause enrichment of LSCs and are unlikely to cure MPN as a monotherapy. Simultaneously targeting JAK2V617F and KLF4 or telomerase may be a novel strategy for MPN therapy, which should be of significance both biologically and clinically.

Naringin targets Zeb1 to suppress osteosarcoma cell proliferation and metastasis

Naringin, a citrus bioflavonoid, has anti-inflammatory actions and cardio- and neuroprotective effects. In addition, naringin exhibits multiple antitumor actions in several cancer types, including osteosarcoma, the most common type of bone cancer. Here, we show that naringin inhibits proliferation and invasion and induces apoptosis in human osteosarcoma cells by inhibiting zinc finger E-box binding homeobox 1 (Zeb1), a transcriptional repressor of epithelial differentiation involved in tumor metastasis. Our expression analyses confirm that Zeb1 is highly expressed in osteosarcoma specimens and cell lines. The effects of naringin, which included downregulation of Cyclin D1, MMP2, and bcl-2, where reproduced by siRNA-mediated Zeb1 silencing, whereas Zeb1 overexpression increased proliferation, migration, and Cyclin D1, MMP2, and bcl-2 levels. In addition, naringin administration reduced tumor nodule formation and attenuated the expression of the above proteins in the livers of mice injected with MG63 osteosarcoma cells. Our study provides preclinical evidence for the potential therapeutic application of naringin in the treatment of osteosarcoma.

Functional characterization of interferon regulatory factor 2 and its role in the transcription of interferon a3 in golden pompano Trachinotus ovatus (Linnaeus 1758)

Similar to mammals, fish possess interferon (IFN) regulatory factor 2 (IRF2)-dependent type I IFN responses. Nevertheless, the detailed mechanism through which IRF2 regulates type I IFNa3 remains largely unknown. In the present study, we first identified two genes from golden pompano (Trachinotus ovatus), IRF2 (ToIRF2) and IFNa3 (ToIFNa3), in the IFN/IRF-based signalling pathway. The open reading frame (ORF) sequence of ToIRF2 encoded 335 amino acids possessing four typical characteristic domains, including a conserved DNA-binding domain (DBD), an interferon association domain 2 (IAD2), a transcriptional activation domain (TAD), and a transcriptional repression domain (TRD). Furthermore, transcripts of ToIRF2 were significantly upregulated after stimulation by polyinosinic: polycytidylic acid [poly (I:C)], lipopolysaccharide (LPS) and flagellin in immune-related tissues (blood, liver, and head-kidney). Moreover, to investigate whether ToIRF2 was a regulator of ToIFNa3, promoter analysis was performed. The results showed that the region from -896 bp to -200 bp is defined as the core promoter using progressive deletion mutations of IFNa3. Additionally, ToIRF2 overexpression led to a clear time-dependent enhancement of ToIFNa3 promoter expression in HEK293T cells. Mutation analyses indicated that the activity of the ToIFNa3 promoter significantly decreased after targeted mutation of M4/5 binding sites. Electrophoretic mobile shift assays (EMSAs) verified that IRF2 interacted with the binding site of the ToIFNa3 promoter region to regulate ToIFNa3 transcription. Last, the promoter activity of ToIFNa3-2 was more responsive to treatment with poly (I:C) than LPS and flagellin. Furthermore, overexpression of ToIRF2 in vitro obviously increased the expression of several IFN/IRF-based signalling pathway genes after poly (I:C) abduction. In conclusion, the present study provides the first evidence of the positive regulation of ToIFNa3 transcription by ToIRF2 and contributes to a better understanding of the transcriptional mechanisms of ToIRF2 in fish.

Knockdown of YAP inhibits growth in Hep-2 laryngeal cancer cells via epithelial-mesenchymal transition and the Wnt/β-catenin pathway

BACKGROUND

Yes-associated protein (YAP) plays a crucial role in tumour development and it is the main effector of the Hippo signalling pathway. However, the mechanism underlying YAP downregulation in laryngeal cancer is still unclear. In our previous study, we found that YAP, compared with adjacent tissues, was expressed higher in laryngeal cancer and was also closely associated with histological differentiation, TNM stage and poor prognosis.

METHODS

In this study, we attempted to determine whether silenced YAP could downregulate human laryngeal carcinoma Hep-2 cells progression. YAP was downregulated in Hep-2 cells by shRNA, and the malignant ability of Hep-2 was assessed in vitro and in vivo.

RESULTS

In vitro, CCK-8, colony formation and wound healing assays showed that downregulation of YAP significantly reduced the rates of proliferation, migration, and invasion in Hep-2 cells. Downregulation of YAP distinctly induced G2/M cycle arrest and increased the rate of apoptosis. Accordingly, western blot assay suggested that the expression of DKK1, vimentin and β-catenin was significantly decreased after YAP downregulated treatment, thereby indicating that YAP mediated the EMT programme and the Wnt/β-catenin signalling pathway in carcinoma of the larynx. Furthermore, silencing of YAP suppressed Hep-2 cell tumourigenesis and metastasis in vivo.

CONCLUSION

In summary, our findings demonstrated the proliferation of YAP downregulation and the invasion of Hep-2 cells via downregulating the Wnt/β-catenin pathway in vitro and in vivo, suggesting that YAP may provide a potential therapeutic strategy for the treatment of laryngeal cancer.

Tumor Suppressor LKB1 inhibits both the mRNA Expression and the Amplification of hTERC by the Phosphorylation of YAP in Lung Cancer Cells

Liver kinase B1 (LKB1) is a critical tumor suppressor that is frequently mutated in human cancers. LKB1 has serine/threonine protein kinase activity, which regulates gene expression by phosphorylation of Yes-Associated protein (YAP). The phosphorylation-dependent YAP shuttling is critically important intracellular mechanism in the Hippo pathway. In our previous study, we found that the amplification of hTERC was significant higher in the bronchial brushing cells of patients with lung cancer, however, the underlying molecular mechanism is not clear. In this study, we showed that LKB1 overexpression could phosphorylate YAP and promoted its nuclear rejection. Silencing LKB1 could dephosphorylate YAP and promoted its entry into the nucleus. Here, we found that LKB1 inhibited the mRNA expression and the amplification of hTERC. YAP further up-regulated hTERC at mRNA and gene amplification levels. Therefore, we suggest that LKB1 may inhibit the expression and amplification of hTERC through the axis of LKB1-pYAP(YAP)-hTERC.

Hypoxia Causes Transgenerational Impairment of Ovarian Development and Hatching Success in Fish

Hypoxia is a pressing environmental problem in both marine and freshwater ecosystems globally, and this problem will be further exacerbated by global warming in the coming decades. Recently, we reported that hypoxia can cause transgenerational impairment of sperm quality and quantity in fish (in F0, F1, and F2 generations) through DNA methylome modifications. Here, we provide evidence that female fish ( Oryzias melastigma) exposed to hypoxia exhibit reproductive impairments (follicle atresia and retarded oocyte development), leading to a drastic reduction in hatching success in the F2 generation of the transgenerational group, although they have never been exposed to hypoxia. Further analyses show that the observed transgenerational impairments in ovarian functions are related to changes in the DNA methylation and expression pattern of two gene clusters that are closely associated with stress-induced cell cycle arrest and cell apoptosis. The observed epigenetic and transgenerational alterations suggest that hypoxia may pose a significant threat to the sustainability of natural fish populations.

Luteolin inhibits cell cycle progression and induces apoptosis of breast cancer cells through downregulation of human telomerase reverse transcriptase

Luteolin is a flavonoid, which has been extensively investigated due to its antitumor effects; however, the underlying mechanisms of its action remain largely unknown. The present study aimed to investigate the role of luteolin in breast cancer (BC), and explored how luteolin suppresses the growth and induces the apoptosis of BC cells. The MTS assay was used to determine the anticancer activity of luteolin. Colony formation and Transwell assays were performed to evaluate the effects of luteolin on cell growth and invasion. Cell cycle progression and apoptosis were analyzed by flow cytometry. In addition, western blotting was performed to analyze cellular apoptosis and signaling pathways elicited by luteolin. The present study revealed that the proliferation of the BC cell line MDA-MB-231 was effectively suppressed by luteolin in a dose-dependent manner. Additionally, luteolin was revealed to increase apoptotic rates in BC cells. Dose-dependent cell cycle arrest in S phase was observed following treatment with luteolin in MDA-MB-231 cells. Mechanistically, luteolin reduced telomerase levels in a dose-dependent manner. Additionally, luteolin inhibited phosphorylation of the nuclear factor-κB inhibitor α and its target gene c-Myc, to suppress human telomerase reverse transcriptase (hTERT) expression, which encodes the catalytic subunit of telomerase. Collectively, the results of the present study indicated that luteolin may inhibit BC cell growth by targeting hTERT, suggesting that the mechanism of hTERT regulation by luteolin may justify further study regarding its potential as a therapeutic target for BC treatment.

β-catenin-coordinated lncRNA MALAT1 up-regulation of ZEB-1 could enhance the telomerase activity in HGF-mediated differentiation of bone marrow mesenchymal stem cells into hepatocytes

OBJECTIVE

To investigate role of β-catenin and lncRNA MALAT1/miR-217 axis to converge into the regulation of ZEB-1 in hepatocyte growth factor (HGF)-induced hepatocytes differentiated from bone marrow mesenchymal stem cells (BM-MSCs).

METHODS

BM-MSCs were isolated and HGF was used to induce the differentiation of BM-MSCs into hepatocytes. HSC-T6 cells, BRL-3 A cells and differentiated BM-MSCs were treated by lipopolysaccharide(LPS). shRNAs were used to silence β-catenin and recombinant plasmids were used to over-express ZEB1. Measurement of cell viability was conducted using MTT assay and Hoechst 33342 staining. RNA immunoprecipitation (RIP) assay was used to determine binding of miR-217-3p and MALAT1.

RESULTS

BM-MSCs successfully differentiated into hepatocytes by HGF treatment. Expression of β-catenin, ZEB-1 and TERT was up-regulated to a higher level in hepatocytes differentiated from BM-MSCs than HSC-T6 cells and BRL-3 A cells after LPS stimulation. When β-catenin was knocked down in all cell lines, expression of β-catenin, ZEB-1 and TERT was significantly decreased as well as telomerase activity. While when ZEB1 was over-expressed, expression of TERT and telomerase activity was all significantly up-regulated. In hepatocytes differentiated from BM-MSCs, miR-217 was down-regulated and lncRNA MALAT1 was up-regulated. RIP analysis showed MALAT1 was physically associated with miR-217 and might function in the regulation of ZEB-1, further enhancing the expression of TERT so as to augment telomerase activity.

CONCLUSION

We successfully used HGF to mediate differentiation of BM-MSCs into hepatocytes, and found that β-catenin-coordinated MALAT1/miR-217 axis could up-regulate expression of ZEB-1 and further enhanced the telomerase activity through regulation of TERT in BM-MSCs differentiating into hepatocytes.

The Transcriptional Factor PPARαb Positively Regulates Elovl5 Elongase in Golden Pompano Trachinotus ovatus (Linnaeus 1758)

The nuclear peroxisome proliferator-activated receptors (PPARs) regulate the transcription of elongases of very long-chain fatty acids (Elovl), which are involved in polyunsaturated fatty acid (PUFA) biosynthesis in mammals. In the present study, we first characterized the function of Elovl5 elongase in Trachinotus ovatus. The functional study showed that ToElovl5 displayed high elongation activity toward C18 and C20 PUFA. To investigate whether PPARαb was a regulator of Elovl5, we also reported the sequence of T. ovatus PPARαb (ToPPARαb). The open reading frame (ORF) sequence encoded 469 amino acids possessing four typical characteristic domains, including an N-terminal hypervariable region, a DNA-binding domain (DBD), a flexible hinge domain and a ligand-binding domain (LBD). Thirdly, promoter activity experiments showed that the region from PGL3-basic-Elovl5-5 (-146 bp to +459 bp) was defined as the core promoter by progressive deletion mutation of Elovl5. Moreover, PPARαb overexpression led to a clear time-dependent enhancement of ToElovl5 promoter expression in HEK 293T cells. Fourth, the agonist of PPARαb prominently increased PPARαb and Elovl5 expression, while PPARαb depletion by RNAi or an inhibitor was correlated with a significant reduction of Elovl5 transcription in T. ovatus caudal fin cells (TOCF). In conclusion, the present study provides the first evidence of the positive regulation of Elovl5 transcription by PPARαb and contributes to a better understanding of the transcriptional mechanism of PPARαb in fish.