The Journal of Biochemistry

MicroRNA-191 regulates endometrial cancer cell growth via TET1-mediated epigenetic modulation of APC

Abstract Endometrial cancer (EC) is a common gynecological malignancy with relatively favourable prognosis, although alternative diagnostic and therapeutic options remain to be explored for advanced disease. Recent studies enabled to apply microRNAs (miRs) to clinical cancer management as promising diagnostic and therapeutic biomarkers. We here aimed to identify proliferation-associated miRNAs and characterize their functions in EC cells. Our small RNA-sequencing analysis showed that miR-191 is abundantly expressed in HEC-1A and Ishikawa EC cells along with the high expression of miR-182, which was previously characterized as an EC proliferation-related miRNA in EC. We showed that miR-191 was upregulated in EC tissues than in adjacent normal tissues and its knockdown repressed EC cell proliferation. In silico miRNA target screening identified that ten–eleven translocation 1 (TET1) is one of the putative miR-191 targets. TET1 expression could be downregulated by miR-191 through the mRNA–miRNA interaction in the 3′-untranslated region of TET1. In line with TET1 functions as a methylcytosine dioxygenase, which removes genome-wide DNA methylation marks, decreased TET1 expression resulted in hypermethylation in the promotor region of tumour suppressor adenomatous polyposis coli. Taken together, miR-191 could function as an oncogenic miRNA in EC and serve as a prospective diagnostic and therapeutic target for advanced disease.

Trehalose decreases mRNA and protein expressions of c-Jun and JunB in human cervical cancer HeLa cells

AbstractIncreasing evidence suggests that trehalose, a non-reducing disaccharide, ameliorates disease phenotypes by activating autophagy in animal models of various human diseases, including neurodegenerative diseases. Multiple in vitro studies suggest that activation of transcription factor EB, a master regulator of lysosomal biogenesis and autophagy genes, is a major contributor to trehalose-induced autophagy at later stages of exposure. However, underlying causes of trehalose-induced autophagy possibly occur at the early stage of the exposure period. In this study, we investigated the effects of short-term exposure of HeLa cells to trehalose on several signal transduction pathways to elucidate the initial events involved in its beneficial effects. Phospho-protein array analysis revealed that trehalose decreases levels of phosphorylated c-Jun, a component of the transcription factor activator protein-1, after 6 h. Trehalose also rapidly reduced mRNA expression levels of c-Jun and JunB, a member of the Jun family, within 1 h, resulting in a subsequent decrease in their protein levels. Future studies, exploring the interplay between decreased c-Jun and JunB protein levels and beneficial effects of trehalose, may provide novel insights into the mechanisms of trehalose action.

Decreased EMILIN2 correlates to metabolism phenotype and poor prognosis of ovarian cancer

Abstract This study aimed to explore the function and related mechanisms of elastin microfibril interfacer 2 (EMILIN2) in ovarian cancer. First, the expression level of EMILIN2 was detected in patient tissues and its correlation with overall survival rate was analysed. Then, EMILIN2 was overexpressed in ovarian cancer cell lines to observe its function and effect on Warburg effect. By detecting its promoter region methylation, the epigenetic regulatory role was explored. Finally, through the luciferase reporter assay and siRNA tools, the regulatory mechanism of p53 on EMILIN2 was investigated. It was detected in clinical samples that down-regulated EMILIN2 was associated with poor prognosis of ovarian cancer. It was further found that EMILIN2 regulated the metabolic phenotype of ovarian cancer cells. The expression of EMILIN2 was epigenetically regulated by its promoter methylation. Also, it was found that p53 regulated the expression of EMILIN2 and the p53/EMILIN2 axis regulated the Warburg effect in ovarian cancer cells. EMILIN2 was inhibited by methylation in ovarian cancer. In summary, p53 can promote and regulate its transcription by binding to the promoter region of EMILIN2, thereby affecting the Warburg effect and inhibiting tumours. Therefore, EMILIN2 might be a potential target for clinical diagnosis and treatment of ovarian cancer.

Nanog-mediated stem cell properties are critical for MBNL3-associated paclitaxel resistance of ovarian cancer

Abstract Paclitaxel (PTX) is the standard first-line treatment of ovarian cancer, but its efficacy is limited by multidrug resistance. Therefore, it is crucial to identify effective drug targets to facilitate PTX sensitivity for ovarian cancer treatment. Seventy PTX-administrated ovarian cancer patients were recruited in this study for gene expression and survival rate analyses. Muscleblind-like-3 (MBNL3) gain-of-function and loss-of-function experiments were carried out in ovarian cancer cells (parental and PTX-resistant) and xenograft model. Cancer cell viability, apoptosis, spheroids formation, Nanog gene silencing were examined and conducted to dissect the underlying mechanism of MBNL3-mediated PTX resistance. High expression of MBNL3 was positively correlated with PTX resistance and poor prognosis of ovarian cancer. MBNL3 increased cell viability and decreased apoptosis in ovarian stem-like cells, through upregulating Nanog. This study suggests the MBNL3-Nanog axis is a therapeutic target for the treatment of PTX resistance in ovarian cancer management.

LncRNA SDHAP1 confers paclitaxel resistance of ovarian cancer by regulating EIF4G2 expression via miR-4465

Abstract Ovarian cancer has ranked as one of the leading causes of female morbidity and mortality around the world, which affects ∼239,000 patients and causes 152,000 deaths every year. Chemotherapeutic resistance of ovarian cancer remains a devastating actuality in clinic. The aberrant upregulation of long non-coding RNA succinate dehydrogenase complex flavoprotein subunit A pseudogene 1 (lncRNA SDHAP1) in the Paclitaxel (PTX)-resistant ovarian cancer cell lines has been reported. However, studies focussed on SDHAP1 in its regulatory function of chemotherapeutic resistance in ovarian cancer are limited, and the detailed mechanisms remain unclear. In this study, we demonstrated that SDHAP1 was upregulated in PTX-resistant SKOV3 and Hey-8 ovarian cancer cell lines while the level of miR-4465 was downregulated. Knocking-down SDHAP1 induced re-acquirement of chemo-sensitivity to PTX in ovarian cancer cells in vitro. Mechanically, SDHAP1 upregulated the expression of EIF4G2 by sponging miR-4465 and thus facilitated the PTX-induced apoptosis in ovarian cancer cells. The regulation network involving SDHAP1, miR-4465 and EIF4G2 could be a potential therapy target for the PTX-resistant ovarian cancer.

Differential roles of two DDX17 isoforms in the formation of membraneless organelles

Abstract The RNA helicase, DDX17 is a member of the DEAD-box protein family. DDX17 has two isoforms: p72 and p82. The p82 isoform has additional amino acid sequences called intrinsically disordered regions (IDRs), which are related to the formation of membraneless organelles (MLOs). Here, we reveal that p72 is mostly localized to the nucleoplasm, while p82 is localized to the nucleoplasm and nucleoli. Additionally, p82 exhibited slower intranuclear mobility than p72. Furthermore, the enzymatic mutants of both p72 and p82 accumulate into the stress granules. The enzymatic mutant of p82 abolishes nucleolar localization of p82. Our findings suggest the importance of IDRs and enzymatic activity of DEAD-box proteins in the intracellular distribution and formation of MLOs.

Long non-coding RNA MIAT promotes cervical cancer proliferation and migration

Abstract Cervical cancer is one of the most common cancers in the world while its pathological mechanisms are not well-elucidated. Long non-coding RNA (lncRNA) has been implicated in cancer development. The dysregulation of lncRNA myocardial infarction-associated transcript (MIAT) has been reported in several cancers while its role in cervical cancer is not described yet. In this study, the role of MIAT in cervical cancer was explored. We evaluated the expression of MIAT in cervical cancer tissues and cell lines. Furthermore, we explored the effects of MIAT on proliferation and invasion of cervical cancer using cell model and animal transplantation model. We also evaluated the effects of MIAT on activation of PI3K/Akt/mTOR signalling pathway. Our results show that MIAT was up-regulated in cervical cancer tissues and cell lines. Knocking down MIAT resulted in decreased cell proliferation, migration and invasion of cervical cancer cells and suppression of tumour growth in mice. Mechanically, knocking down MIAT suppressed the activation of PI3K/Akt signalling pathway. In conclusion, MIAT promotes cell proliferation and invasion in cervical cancer.

Nuclear accumulation of ZFP36L1 is cell cycle-dependent and determined by a C-terminal serine-rich cluster

Abstract ZFP36L1 is an RNA-binding protein responsible for mRNA decay in the cytoplasm. ZFP36L1 has also been suggested as a nuclear-cytoplasmic shuttling protein because it contains a potential nuclear localization signal and a nuclear export signal. However, it remains unclear how the nuclear localization of ZFP36L1 is controlled. In this study, we provide evidence that the nuclear accumulation of ZFP36L1 protein is modulated in a cell cycle-dependent manner. ZFP36L1 protein accumulation in fractionated nuclei was particularly prominent in cells arrested at G1-/S-phase boundary, while it was downregulated in S-phase cells, and eventually disappeared in G2-phase nuclei. Moreover, forced nuclear targeting of ZFP36L1 revealed marked downregulation of this protein in S- and G2-phase cells, suggesting that ZFP36L1 can be eliminated in the nucleus. The C-terminal serine-rich cluster of ZFP36L1 is critical for the regulation of its nuclear accumulation because truncation of this probable disordered region enhanced the nuclear localization of ZFP36L1, increased its stability and abolished its cell cycle-dependent fluctuations. These findings provide the first hints to the question of how ZFP36L1 nuclear accumulation is controlled during the course of the cell cycle.

C-Myc-activated long non-coding RNA PVT1 enhances the proliferation of cervical cancer cells by sponging miR-486-3p

Abstract Cervical cancer is one of the most prevalent gynecological malignancies. Although the functions of long non-coding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1) and c-Myc in tumorigenesis have been acknowledged, the roles of c-Myc and lncRNA-PVT1 in the proliferation of cervical cancer are still unclear. Our study is designed to demonstrate the regulatory network involving c-Myc and lncRNA-PVT1 in cervical cancer. Quantitative real-time PCR and western blot assays were performed in our research to estimate the expression levels of RNA and proteins. CCK8 assays were applied to demonstrate the viability of HeLa and SiHa cells. Immunofluorescence assay was then used to investigate the co-localization of lncRNA-PVT1 and miR-486-3p. Binding of c-Myc to the promoter region of PVT1 was identified by ChIP-assay. Functionally, upregulation of lncRNA-PVT1 enhanced the proliferation and viability of cervical cancer cells. Mechanistically, lncRNA-PVT1 sponged miR-486-3p and released its repression of extracellular matrix protein 1. Besides, c-Myc functioned as an activator of lncRNA-PVT1 and upregulated its expression by binding to the promoter of PVT1 in cervical cancer cells. lncRNA-PVT1 was upregulated by c-Myc and thus enhanced the proliferation of cervical cancer cells by sponging miR-486-3p.

TXNIP induced by MondoA, rather than ChREBP, suppresses cervical cancer cell proliferation, migration and invasion

Abstract Evidence has indicated the associations between thioredoxin-interacting protein (TXNIP) and cancers. However, the role of TXNIP in cervical cancer remains unclear. Hence, this study aims to investigate the role of TXNIP in regulating cervical cancer cell proliferation, migration and invasion. TXNIP expression can be regulated by either MondoA or ChREBP in a cell- or tissue- dependent manner. Thus, we also explored whether TXNIP expression in cervical cancer can be regulated by MondoA or ChREBP. Our results showed that TXNIP expression was decreased in cervical cancer cells (HeLa, SiHa, CaSki, MS751, C-33A). Furthermore, TXNIP overexpression inhibited cell proliferation, migration and invasion in HeLa cells, whereas TXNIP silencing exerted the opposite effect in C-33A cells. Moreover, TXNIP expression could be induced by MondoA, rather than ChREBP in HeLa cells. Additionally, MondoA overexpression inhibited cell proliferation, migration and invasion through upregulating TXNIP in HeLa cells. In summary, TXNIP induced by MondoA, rather than ChREBP, suppresses cervical cancer cell proliferation, migration and invasion. Our findings provide new ideas for the prevention and treatment of cervical cancer.