FZD7 Expression Research Articles

Abstract A76: Role of frizzled-7 in platinum tolerance ovarian cancer

Abstract While ovarian cancer (OC) is considered as a highly chemoresponsive tumor, 75% women experience tumor relapse associated with chemoresistance. It has been hypothesized that ovarian cancer stem cells (OCSCs) are responsible for developing chemoresistant recurrent tumors and sharing characteristics with normal SCs. Measuring aldehyde dehydrogenase 1 (ALDH1) enzymatic activity has been demonstrated as an established method for OCSC identification and isolation. Our previous studies indicated that while chemotherapy initially “debulks” the mass of OC, residual tumors are enriched in OCSCs. Here, we aimed to identify new markers for CSC enriched platinum-resistant OCs using in vitro and in vivo models. We found that the surviving cells after repeated treatment with platinum were enriched in ALDH(+) cells, formed more spheroids and contained cells expressing CSC-related transcription factors (Sox 2) compared to parental cells, supporting that repeated platinum treatment selects cells with stem-like properties. Next, CSC RT-PCR based platform was used to compare wild-type and chemoresistant OCs and to rule out candidate genes that may drive stemness and chemoresistance. CSC array showed that Frizzled 7 receptor (FZD7), a transmembrane receptor involved in canonical Wnt/β-catenin, emerged as a top highly expressed marker in platinum-resistant compared to parental cells and was next studied as a putative new marker for CSC-enriched chemoresistant OCs. FZD7 expression was increased in platinum-resistant cells compared to parental cells at mRNA and protein levels. FZD7(+) cells were detectable and represent ~2-15% on OC cell lines and cells dissociated from human tumors. FZD7(+) population enriched in the platinum-resistant OCs and xenografts. In addition, KD FZD7 in chemoresistant OC cells restored chemosensitivity of OCs, decreased spheroid formation, and delayed tumor initiation, suggesting the role of FZD7 in regulating chemoresistance and stemness of OCs. RNA sequencing results of FZD7(+)/FZD7(-) OCs revealed that FZD7(+) cells downregulated genes associated to DNA damage response, and upregulated “persister cells” related genes, including EMT and stemness-associated genes. Importantly, mitochondrial dysfunction and oxidative phosphorylation were enriched in FZD7(-) OCs compared with FZD7(+) cells. As “persister cells” have been demonstrated to be dependent on antioxidant protein, glutathione peroxidase 4 (GPX4), for cell survival and maintaining mitochondrial oxidative phosphorylation in other cancer models, we checked GPX4 expression in FZD7(+) OCs and platinum-resistant OCs; the expression of GPX4 is correlated with FZD7 expression associated with chemoresistance. Platinum-resistant cells are more sensitive to GPX4 inhibitor treatment and KD FZD7 decreased GPX4 expression and blunt sensitivity of OCs to GPX4 inhibitor treatment, further supporting that platinum-resistant OCs are “persister like cells,” which are protected by GPX4 from lipid peroxidation stress and ferroptosis. Citation Format: Yinu Wang, Guanyuan Zhao, Hao Huang, Salvatore Condello, Jianjun Wei, Daniela Matei. Role of frizzled-7 in platinum tolerance ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr A76.

FZD10 regulates cell proliferation and mediates Wnt1 induced neurogenesis in the developing spinal cord.

Wnt/FZD signalling activity is required for spinal cord development, including the dorsal-ventral patterning of the neural tube, where it affects proliferation and specification of neurons. Wnt ligands initiate canonical, β -catenin-dependent, signaling by binding to Frizzled receptors. However, in many developmental contexts the cognate FZD receptor for a particular Wnt ligand remains to be identified. Here, we characterized FZD10 expression in the dorsal neural tube where it overlaps with both Wnt1 and Wnt3a, as well as markers of dorsal progenitors and interneurons. We show FZD10 expression is sensitive to Wnt1, but not Wnt3a expression, and FZD10 plays a role in neural tube patterning. Knockdown approaches show that Wnt1 induced ventral expansion of dorsal neural markes, Pax6 and Pax7, requires FZD10. In contrast, Wnt3a induced dorsalization of the neural tube is not affected by FZD10 knockdown. Gain of function experiments show that FZD10 is not sufficient on its own to mediate Wnt1 activity in vivo. Indeed excess FZD10 inhibits the dorsalizing activity of Wnt1. However, addition of the Lrp6 co-receptor dramatically enhances the Wnt1/FZD10 mediated activation of dorsal markers. This suggests that the mechanism by which Wnt1 regulates proliferation and patterning in the neural tube requires both FZD10 and Lrp6.

SMAD4 activates Wnt signaling pathway to inhibit granulosa cell apoptosis

The TGF-β and Wnt signaling pathways are interrelated in many cell types and tissues, and control cell functions in coordination. Here, we report that SMAD4, a downstream effector of the TGF-β signaling pathway, induces FZD4, a receptor of the Wnt signaling pathway, establishing a novel route of communication between these two pathways in granulosa cells (GCs). We found that SMAD4 is a strong inducer of FZD4, not only initiating FZD4 transcription but also activating FZD4-dependent Wnt signaling and GC apoptosis. Furthermore, we identified the direct and indirect mechanisms by which SMAD4 promotes expression of FZD4 in GCs. First, SMAD4 functions as a transcription factor to directly bind to the FZD4 promoter region to increase its transcriptional activity. Second, SMAD4 promotes production of SDNOR, a novel lncRNA that acts as a sponge for miR-29c, providing another mean to block miR-29c from degenerating FZD4 mRNA. Overall, our findings not only reveal a new channel of crosstalk between the TGF-β and Wnt signaling pathways, SMAD4–FZD4 axis, but also provide new insights into the regulatory network of GC apoptosis and follicular atresia. These RNA molecules, such as miR-29c and lnc-SDNOR, represent potential targets for treatment of reproductive diseases and improvement of female fertility.

Investigating the role of Fzd‐7 in liver donation and regeneration

The Wnt‐Fzd‐LRP5/6‐β‐catenin signaling axis has important roles in liver homeostasis, regeneration and disease. Through use of liver‐ and cell‐type‐specific gene knockout mouse models, we and others have confirmed roles for β‐catenin and LRP5/6 in regulating metabolic zonation of the liver as well as initiation of liver regeneration after partial hepatectomy. Similarly, using cell‐type‐specific Wls gene knockout models we have identified endothelial cells and Kupffer cells as significant sources of Wnt proteins responsible for regulating β‐catenin signaling in liver regeneration. However, little is known about the actual frizzled (Fzd) receptor(s) that are critical to transmitting the Wnt signals that regulate metabolic zonation and liver regeneration. We do know that Fzd‐7 is highly expressed in some liver cancers. Here, we further investigate the role of Fzd‐7 in metabolic zonation and liver regeneration after partial hepatectomy. We used microdissection to isolate cells from 3 major zones of the liver (peri‐portal, mid‐zonal, pericentral) to assess the expression of Fzd receptors in each zone by qPCR. We observed ~3‐fold higher expression of Fzd‐7 in the pericentral zone, indicating a possible role in metabolic zonation. We also examined and found upregulation of Fzd‐7 gene expression at 12–24h after hepatectomy in mice. Therefore, we obtained Fzd‐7‐floxed mice to conditionally delete Fzd‐7 in the liver and investigate its role in metabolic zonation and liver regeneration. We injected Fzd‐7 floxed mice with AAV8‐TBG‐Cre to conditionally knockout Fzd‐7 from hepatocytes. Two weeks after administration of AAV8‐TBG‐Cre, we performed PCR analysis and confirmed successful knockout of the Fzd‐7 mRNA as well as detection of the floxed‐deletion in the liver DNA. However, analysis of GS and CYP2e1 showed no defect in metabolic zonation at 2 weeks post AAV injection. We also performed partial hepatectomy 14 days after AAV‐TBG‐Cre injection and analyzed the regenerating livers. Hepatocyte proliferation by BrdU staining was marginally lower in the AAV8‐Cre injected mice at 40h post hepatectomy indicating a possible delay in liver regeneration. Further characterization has shown compensatory increases in expression of other Fzd receptors in the AAV8‐Cre livers which may explain the lack of overt phenotype in these mice. Since Fzd‐7 protein may have longer half‐life, extended time points after AAV8‐TBG‐Cre injection to Fzd‐7‐floxed mice are currently under investigation. Additional characterization with Alb‐Cre‐Fzd‐7 liver knockouts is also being done. In conclusion, Fzd‐7 expression is highest in zone‐3 and is also upregulated early after hepatectomy. While acute deletion of Fzd‐7 did not reveal changes in zonation, a decrease in hepatocyte proliferation during regeneration was evident. Fzd‐7 may be an important mediator of Wnt‐β‐catenin signaling in the liver.Support or Funding InformationDepartment of Pathology and Pittsburgh Liver Research Center, University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA

Transforming Growth Factor Beta (TGF-β) Regulates Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells by Promoting Wnt Signaling Pathway in Atrophic Nonunion

During atrophic nonunion, Wnt signaling pathway is inhibited, resulting in inhibition of BMSC osteogenic differentiation. TGF-β regulates growth and development of the body. However, TGF-β’s effect on osteogenic differentiation of BMSCs in atrophic nonunion has not been reported. The bone tissue and serum of patients with atrophic nonunion and normal healing fractures were collected, and TGF-β mRNA and serum secretion were analyzed by Real time PCR and ELISA. Rat BMSCs were cultured and randomly divided into control group, TGF-β group and TGF-β siRNA group which was transfected with pcDNA-TGF-β plasmid or TGF-β siRNA respectively followed by analysis of cell proliferation by MTT assay, alkaline phosphatase (ALP) activity, Caspase3 activity, expression of RUNX2 and OPN and PPARγ2 mRNA by Real time PCR, and WNT5A and FZD3 expression by Western blot. TGF-β mRNA level and secretion in patients with atrophic nonunion was significantly reduced compared with patients with normal healing fractures (P < 0.05). Transfection of TGF-β siRNA down-regulated TGF-β expression in BMSCs, significantly inhibited cell proliferation, increased Caspase3 activity, decreased ALP activity, RUNX2 and OPN expression, increased PPARγ2 expression and deceased WNT5A and FZD3 expression (P < 0.05). However, transfection of pcDNA-TGF-β plasmid up-regulated TGF-β expression in BMSCs and reversed the above changes (P < 0.05). TGF-β is reduced in atrophic nonunion patients. Targeting TGF-β promotes BMSCs proliferation and osteogenic differentiation by regulating Wnt signaling pathway.

Frizzled-4 is required for normal bone acquisition despite compensation by Frizzled-8.

The activation of the Wnt/β-catenin signaling pathway is critical for skeletal development but surprisingly little is known about the requirements for the specific frizzled (Fzd) receptors that recognize Wnt ligands. To define the contributions of individual Fzd proteins to osteoblast function, we profiled the expression of all 10 mammalian receptors during calvarial osteoblast differentiation. Expression of Fzd4 was highly upregulated during in vitro differentiation and therefore targeted for further study. Mice lacking Fzd4 in mature osteoblasts had normal cortical bone structure but reduced cortical tissue mineral density and also exhibited an impairment in the femoral trabecular bone acquisition that was secondary to a defect in the mineralization process. Consistent with this observation, matrix mineralization, markers of osteoblastic differentiation, and the ability of Wnt3a to stimulate the accumulation of β-catenin were reduced in cultures of calvarial osteoblasts deficient for Fzd4. Interestingly, Fzd4-deficient osteoblasts exhibited an increase in the expression of Fzd8 both in vitro and in vivo, which suggests that the two receptors may exhibit overlapping functions. Indeed, ablating a single Fzd8 allele in osteoblast-specific Fzd4 mutants produced a more severe effect on bone acquisition. Taken together, our data indicate that Fzd4 is required for normal bone development and mineralization despite compensation from Fzd8.

MicroRNA-1286 inhibits osteogenic differentiation of mesenchymal stem cells to promote the progression of osteoporosis via regulating FZD4 expression.

The aim of this study was to investigate whether microRNA-1286 could inhibit the osteogenic differentiation of human marrow mesenchymal stem cells (hMSCs) by regulating FZD4 expression and promoting the progression of osteoporosis. Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was used to detect the expression of microRNA-1286 in the serum of patients with osteoporosis. Meanwhile, microRNA-1286 expression in different stages of osteogenic differentiation of hMSCs was measured by qRT-PCR as well. After overexpression of microRNA-1286 and FZD4 in hMSCs, the mRNA expression levels of microRNA-1286, alkaline phosphatase (ALP), RUNX2 and osteocalcin (OCN) were detected by qRT-PCR. The protein expression levels of RUNX2 and OCN were detected by Western blot. Meanwhile, alkaline phosphatase (ALP) activity and expression in cells were examined using ALP assay kit and ALP staining method, respectively. Cell mineralized nodules were detected through the alizarin red staining test. Bioinformatics method was used to predict the binding site of microRNA-1286 to FZD4. Subsequent luciferase reporter gene assay was performed to verify whether microRNA-1286 could combine with FZD4. After overexpression or knockdown of microRNA-1286, the mRNA and protein expressions of FZD4 were analyzed using qRT-PCR and Western blot assay, respectively. After the simultaneous overexpression of microRNA-1286 and FZD4 in hMSCs, the mRNA expression levels of ALP, RUNX2 and OCN, ALP activity and content, and cell mineralization ability were successively examined. The expression of microRNA-1286 in the serum of patients with osteoporosis was significantly higher than that of the normal population. Meanwhile, microRNA-1286 expression decreased with the increase of osteogenic differentiation days of hAMSCs. After the overexpression of microRNA-1286, ALP, RUNX2, and OCN levels, ALP activity, RUNX2, and OCN protein levels, as well as mineralized nodule formation were significantly reduced. However, results were reversed when FZD4 was simultaneously up-regulated. Luciferase reporter gene assay results verified that microRNA-1286 could bind to FZD4. After the overexpression of microRNA-1286, the mRNA and protein expressions of FZD4 were found significantly down-regulated. However, results were reversed after knocking down microRNA-1286. Furthermore, the simultaneous overexpression of microRNA-1286 and FZD4 could counteract the inhibitory effect of over-expression of microRNA-1286 on osteogenic differentiation of hMSCs. MicroRNA-1286 can regulate FZD4 expression and inhibit osteogenic differentiation of hMSCs, thereby promoting the development of osteoporosis.

Expression of LGR5, FZD7, TROY, and MIST1 in Perioperatively Treated Gastric Carcinomas and Correlation with Therapy Response.

The cancer stem cell model is considered as a putative cause of resistance to chemotherapy and disease recurrence in malignant tumors. In this study, we tested the hypothesis that the response to neoadjuvant/perioperative chemotherapy correlates with the expression of four different putative cancer stem cell markers of gastric cancer (GC), i.e., LGR5, FZD7, TROY, and MIST1. The expression of LGR5, FZD7, TROY, and MIST1 was assessed by immunohistochemistry in 119 perioperatively treated GCs including pretherapeutic biopsies, resected primary GCs, and corresponding nodal and distant metastases. All four markers were detected in our cohort with variable prevalence and histoanatomical distributions. Few tumor cells expressed TROY. LGR5, FZD7, and MIST1 were coexpressed in 41.2% and completely absent in 6.2%. The prevalence of LGR5- and FZD7-positive GCs was higher and of TROY-positive GCs lower in perioperatively treated GCs compared with treatment-naïve tumors. LGR5, FZD7, and MIST1 in the primary tumors correlated significantly with their expression in the corresponding lymph node metastasis. An increased expression of LGR5 in primary GC correlated significantly with tumor regression. The expression of MIST1 in lymph node metastases correlated significantly with the number of lymph node metastases as well as overall and tumor-specific survival. FZD7 did not correlate with any clinicopathological patient characteristic. Our study on clinical patient samples shows that GCs may coexpress independently different stem cell markers; that neoadjuvant/perioperative treatment of GC significantly impacts on the expression of stem cell markers, which cannot be predicted by the analysis of pretherapeutic biopsies; and that their expression and tumor biological effect are heterogeneous and have to be viewed as a function of histoanatomical distribution.

Targeting Frizzled-7 Decreases Stemness and Chemotherapeutic Resistance in Gastric Cancer Cells by Suppressing Myc Expression

BackgroundAlthough the promoting roles of Frizzled-7 (Fzd7) have been shown before, its effects in gastric cancer (GC) cell stemness are still unclear. The present study assessed the effects of Fzd7 on GC cell stemness and chemoresistance.Material/MethodsClinical samples were used to detect Fzd7 expression and online datasets were used to analyze the correlation between Fzd7 expression and GC patient prognosis. Quantitative real-time PCR (qPCR), Western blot, and spheroid formation were used to detect the stemness of cells and Fzd7-mediated effects on GC cell stemness. Cell viability was assessed to evaluate the role of Fzd7 in chemoresistance of GC cells.ResultsWe found that the expression of Frizzled-7 (Fzd7), a Wnt receptor, was increased in gastric cancer (GC) cells and tissues. Additionally, Fzd7 expression was correlated with shorter overall survival of GC patients. Knockdown of Fzd7 or using inhibitors of Wnt/Fzd (OMP-18R5/Vantictumad) decreased GC cell stemness, characterized as a decrease of spheroid formation ability and expression of stemness regulators. Notably, Fzd7 knockdown or inhibitors of Wnt/Fzd attenuated the chemoresistance of GC cells. Furthermore, elevation of Myc expression rescued the effects of Fzd7 inhibition on GC cell stemness and chemoresistance.ConclusionsOur results suggest that inhibition of Fzd7 decreases the stemness and chemotherapeutic resistance of GC cells.

LncRNA ASB16-AS1 Promotes Growth And Invasion Of Hepatocellular Carcinoma Through Regulating miR-1827/FZD4 Axis And Activating Wnt/β-Catenin Pathway.

BackgroundTo date, although several long noncoding RNAs (lncRNAs) are reported to regulate hepatocellular carcinoma (HCC) development, their relationship still remains elusive. ASB16-AS1 is a poorly researched novel lncRNA. We aimed to investigate its function in HCC progression.MethodsqRT-PCR and in situ hybridization (ISH) were used to analyze ASB16-AS1 expression in HCC tissues. CCK8, Edu incorporation and colony formation were used to determine cell proliferation. Transwell assay was used to examine migration and invasion. Luciferase reporter assay was used to analyze the interactions among ASB16-AS1, miR-1827 and FZD4.ResultsBioinformatics analysis identified ASB16-AS1 was overexpressed in HCC tissues, which was further validated by qRT-PCR and in situ hybridization (ISH). Besides, ASB16-AS1 was demonstrated to be a potential indicator for HCC prognosis. Functional studies showed ASB16-AS1 knockdown attenuated proliferation, migration and invasion of HCC cells. Mechanistically, ASB16-AS1 directly interacted with miR-1827 and promoted FZD4 expression by sponging miR-1827. Overexpressed FZD4 eventually activated Wnt/β-catenin pathway and contributed to HCC progression.ConclusionOur work is the first to identify ASB16-AS1 as an oncogene that enhances HCC progression by modulating miR-1827/FZD4/Wnt/β-catenin pathways.

WNT2b Activates Epithelial-mesenchymal Transition Through FZD4: Relevance in Penetrating Crohn´s Disease.

Epithelial-mesenchymal transition [EMT] has been related to fibrosis and fistula formation, common complications associated with Crohn´s disease [CD]. The WNT signalling pathway mediates EMT, and specific WNT/FZD interactions have been related to the activation of this process in several diseases. We aim to analyse the relevance of EMT and WNT ligands and receptors in the penetrating behaviour of CD. Intestinal surgical resections were obtained from control and CD patients with a stenotic or penetrating behaviour. Fibrosis was determined by the histological analysis of collagen deposition and EMT by confocal microscopy. The expression of WNT ligands, inhibitors, and FZD receptors was analysed by RT-PCR, WB, IH, and IF studies. The effects of WNT2b and the role of FZD4 in EMT were analysed in HT29 epithelial cells. Fibrosis and expression of EMT markers were detected in samples from CD patients irrespective of the clinical behaviour. However, an increased colocalisation of E-CADHERIN and VIMENTIN, an increased number of cells expressing WNT2b, and a higher expression of FZD4 and WNT2b/FZD4 interaction, were detected in intestinal tissue from the penetrating compared with the stenotic CD behaviour. WNT2b induced EMT in HT29 cells through FZD4 activation. An increased EMT, associated with increased WNT2b/FZD4 interaction, was detected in intestinal tissue from CD patients with a penetrating behaviour. WNT2b, through FZD4 activation, induces EMT in vitro which points to a novel pharmacological target to prevent intestinal penetrating complications of CD.

Topologically correct central projections of tetrapod inner ear afferents require Fzd3

Inner ear sensory afferent connections establish sensory maps between the inner ear hair cells and the vestibular and auditory nuclei to allow vestibular and sound information processing. While molecular guidance of sensory afferents to the periphery has been well studied, molecular guidance of central projections from the ear is only beginning to emerge. Disorganized central projections of spiral ganglion neurons in a Wnt/PCP pathway mutant, Prickle1, suggest the Wnt/PCP pathway plays a role in guiding cochlear afferents to the cochlear nuclei in the hindbrain, consistent with known expression of the Wnt receptor, Frizzled3 (Fzd3) in inner ear neurons. We therefore investigated the role of Wnt signaling in central pathfinding in Fzd3 mutant mice and Fzd3 morpholino treated frogs and found aberrant central projections of vestibular afferents in both cases. Ear transplantations from knockdown to control Xenopus showed that it is the Fzd3 expressed within the ear that mediates this guidance. Also, cochlear afferents of Fzd3 mutant mice lack the orderly topological organization observed in controls. Quantification of Fzd3 expression in spiral ganglion neurons show a gradient of expression with Fzd3 being higher in the apex than in the base. Together, these results suggest that a gradient of Fzd3 in inner ear afferents directs projections to the correct dorsoventral column within the hindbrain.

Wnt-11 as a Potential Prognostic Biomarker and Therapeutic Target in Colorectal Cancer.

The expression of the secreted factor Wnt-11 is elevated in several types of cancer, including colorectal cancer, where it promotes cancer cell migration and invasion. Analysis of colorectal cancer gene expression databases associated WNT11 mRNA expression with increased likelihood of metastasis in a subset of patients. WNT11 expression was correlated with the expression of the Wnt receptors FZD6, RYK, and PTK7, and the combined expression of WNT11, FZD6 and RYK or PTK7 was associated with an increased risk of 5-year mortality rates. Immunohistochemical analysis of Wnt-11 in a cohort of 357 colorectal cancer patients found significantly higher Wnt-11 levels in tumors, compared with benign tissue. Elevated Wnt-11 levels occurred more frequently in rectal tumors than in colonic tumors and in tumors from women than men. In univariate analysis, increased Wnt-11 expression was also associated with tumor invasion and increased 5-year mortality. High Wnt-11 levels were not associated with high levels of nuclear β-catenin, suggesting Wnt-11 is not simply an indicator for activation of β-catenin-dependent signaling. Expression of Wnt-11 in colorectal cancer cell lines expressing low endogenous Wnt-11 inhibited β-catenin/Tcf activity and increased ATF2-dependent transcriptional activity. WNT11 gene silencing and antibody-mediated inhibition of Wnt-11 in colorectal cancer cell lines expressing high Wnt-11 reduced their capacity for invasion. Together, these observations suggest that Wnt-11 could be a potential target for the treatment of patients with invasive colorectal cancer.

LncRNA AWPPH promotes osteosarcoma progression via activation of Wnt/β-catenin pathway through modulating miR-93-3p/FZD7 axis

Long noncoding RNAs (lncRNAs) have important regulatory roles in osteosarcoma (OS) progression. Recent researches have shown lncRNA AWPPH promotes lung cancer progression and bladder cancer development. Yet, the function of AWPPH in OS is unknown. In this research, results indicated AWPPH levels were increased in OS tissues in contrast to paracancerous controls. Up-regulated AWPPH was associated with advanced stage, tumor size and metastasis. Besides, AWPPH up-regulation indicated a low survival rate in OS patients. Silencing of AWPPH suppressed proliferation, migration and invasion of OS cells. Mechanistically, AWPPH was demonstrated to sponge miR-93-3p and promote FZD7 expression, causing activation of Wnt/β-catenin. Inhibition of miR-93-3p effectively reversed the effects of AWPPH knockdown on OS cells. Collectively, our findings suggested AWPPH may be a prognostic biomarker and potential therapeutic target. AWPPH enhances FZD7-mediated activation of Wnt/β-catenin by sponging miR-93-3p to promote OS progression.

Long noncoding RNA DLX6-AS1 promotes tumorigenesis by modulating miR-497-5p/FZD4/FZD6/Wnt/β-catenin pathway in pancreatic cancer.

BackgroundLong noncoding RNAs (lncRNAs) are abnormally expressed in various human tumors and play an important role in multiple tumorigeneses, including pancreatic cancer (PC).Materials and methodsThe present study was designed to evaluate the role of lncRNA DLX6-AS1 in tumorigenesis of PC. The expression of DLX6-AS1 and its effect on proliferation, apoptosis, migration, and invasion was investigated in vitro. Its effect on tumor growth and metastasis in vivo and its potential targets were also examined.ResultsWe observed that DLX6-AS1 was highly expressed in PC tissues and PC cell lines, and was negatively correlated with the survival of PC patients. We found that overexpression of DLX6-AS1 promoted proliferation, migration, and invasion of PC cells, inhibited apoptosis, increased Bcl-2, cyclin D1, and MMP-2 expression, and decreased cleaved caspase 3, p27, and E-cadherin expression in PC cells. In addition, overexpression of DLX6-AS1 promoted PC growth by increasing tumor volume and weight and increasing the number of liver and lung metastatic foci. Knockdown of DLX6-AS1 showed an opposite effect in all the experiments. miR-497-5p was demonstrated to be a direct target of DLX6-AS1 and was regulated by DLX6-AS1. We also demonstrated that miR-497-5p targeted FZD4 and FZD6 and decreased their expression. miR-497-5p mimics also decreased the expression of FZD4, FZD6, and β-catenin; the expression of FZD4 or FZD6 was reversed by the overexpression of vectors FZD4 or FZD6, respectively, while the expression of β-catenin was reversed by either vector. Finally, the effect of DLX6-AS1 on proliferation, cell cycle, migration, invasion, and apoptosis of cells and expression of FZD4, FZD6, and β-catenin was neutralized by overexpression of vectors of miR-497-5p, FZD4, or FZD6, totally or partially.ConclusionCollectively, these findings suggested that DLX6-AS1/miR-497-5p/FZD4/FZD6/Wnt/β-catenin signaling pathway is involved in the pathogenesis of PC, and DLX6-AS1 could be a potential biomarker and target for PC treatment.

Identification of the X-linked germ cell specific miRNAs (XmiRs) and their functions.

MicroRNAs (miRNAs) play a critical role in multiple aspects of biology. Dicer, an RNase III endonuclease, is essential for the biogenesis of miRNAs, and the germ cell-specific Dicer1 knockout mouse shows severe defects in gametogenesis. How miRNAs regulate germ cell development is still not fully understood. In this study, we identified germ cell-specific miRNAs (miR-741-3p, miR-871-3p, miR-880-3p) by analyzing published RNA-seq data of mouse. These miRNA genes are contiguously located on the X chromosome near other miRNA genes. We named them X chromosome-linked miRNAs (XmiRs). To elucidate the functions of XmiRs, we generated knockout mice of these miRNA genes using the CRISPR/Cas9-mediated genome editing system. Although no histological abnormalities were observed in testes of F0 mice in which each miRNA gene was disrupted, a deletion covering miR-871 and miR-880 or covering all XmiRs (ΔXmiRs) resulted in arrested spermatogenesis in meiosis in a few seminiferous tubules, indicating their redundant functions in spermatogenesis. Among candidate targets of XmiRs, we found increased expression of a gene encoding a WNT receptor, FZD4, in ΔXmiRs testis compared with that in wildtype testis. miR-871-3p and miR-880-3p repressed the expression of Fzd4 via the 3′-untranslated region of its mRNA. In addition, downstream genes of the WNT/β-catenin pathway were upregulated in ΔXmiRs testis. We also found that miR-871, miR-880, and Fzd4 were expressed in spermatogonia, spermatocytes and spermatids, and overexpression of miR-871 and miR-880 in germ stem cells in culture repressed their increase in number and Fzd4 expression. Previous studies indicated that the WNT/β-catenin pathway enhances and represses proliferation and differentiation of spermatogonia, respectively, and our results consistently showed that stable β-catenin enhanced GSC number. In addition, stable β-catenin partially rescued reduced GSC number by overexpression of miR-871 and miR-880. The results together suggest that miR-871 and miR-880 cooperatively regulate the WNT/β-catenin pathway during testicular germ cell development.

Hypermethylation of Frizzled1 is associated with Wnt/\u03b2-catenin signaling inactivation in mesenchymal stem cells of patients with steroid-associated osteonecrosis

The Wnt/β-catenin signaling pathway is associated with the pathogenesis of steroid-induced osteonecrosis. Our investigation studied whether aberrant CpG island hypermethylation of the FZD1 gene was present in patients with osteonecrosis of the femoral head (ONFH), which results in Wnt/β-catenin signaling inactivation and subsequent cell dysfunction. Bone marrow was collected from the proximal femurs of patients with steroid-associated ONFH (n = 21) and patients with new femoral neck fractures (n = 22), and then mesenchymal stem cells (MSCs) were isolated. We investigated cell viability, the transcription and translation levels of Wnt/β-catenin signaling-related genes, the extent of methylation at CpG islands of the FZD1 promoter, and the osteogenic and adipogenic differentiation abilities of MSCs from the control group and from the ONFH group treated with or without 5′-Aza-dC. According to the results, MSCs from the ONFH group showed a reduced proliferation ability, low transcription and translation levels of FZD1, inhibition of the Wnt/β-catenin signaling pathway, weakened osteogenesis and enhanced adipogenesis ability. Aberrant CpG island hypermethylation of FZD1 was observed in the ONFH group. Treatment with 5’-Aza-dC resulted in de novo FZD1 expression, reactivation of the Wnt/β-catenin signaling pathway and promotion of osteogenesis. Taken together, our study not only provides novel insights into the regulation of the Wnt/β-catenin signaling pathway in this disease but also reveals potential for the use of demethylating agents for the treatment of GC-associated ONFH.

Biological Analysis of Gene Expression and Clinical Variables Suggest FZD1 as a Novel Biomarker for Patients with Kashin-Beck Disease, an Endemic Osteoarthritis in China.

Clinical variables contribute to the severity of Kashin-Beck disease (KBD). However, it is unclear if there is a correlation between gene expression and clinical variables. Peripheral blood samples were collected from 100 patients with KBD and 100 healthy controls from KBD-endemic areas to identify differentially expressed genes in KBD. Correlation analysis and multiple logistic regression analysis were performed using gene expression and clinical parameters. Immunohistochemistry (IHC) was used to detect the expression of related proteins in articular cartilage tissues. Thirty-nine differentially expressed genes were identified in patients with KBD. Nine differentially expressed genes were correlated with the metacarpal length/metacarpal breadth index. FZD1 was identified as having statistical significance in establishing the regression model of clinical parameters and gene expression. FZD1 expression levels were remarkably reduced in patients with KBD. Our results indicate that FZD1 could be involved in the pathological process of phalanges tuberositas and brachydactylia and may provide new insight into the pathogenesis of articular cartilage destruction observed in patients with KBD.

CircRNA_100290 promotes colorectal cancer progression through miR-516b-induced downregulation of FZD4 expression and Wnt/β-catenin signaling

Accumulating evidence indicates that circular RNAs (circRNA) exert crucial functions in the development and advance of cancers. CircRNA_100290 has been reported to promote proliferation in oral cancer. However, whether it participates in colorectal cancer (CRC) remains unclear. Here, our report showed that circRNA_100290 level was significantly increased in CRC tissues and cell lines. Besides, circRNA_100290 expression was positively correlated with tumor metastasis while inversely correlated with prognosis. Silencing circRNA_100290 markedly reduced cell proliferation rate, inhibited migration and invasion abilities, but promoted apoptosis in vitro. Mechanistically, our data revealed circRNA_100290 was a competing endogenous RNA (ceRNA) of FZD4 by sponging miR-516b, leading to activation of Wnt/β-catenin pathway. Rescue assay indicated that FZD4-induced activation of β-catenin pathway is indispensable for the function of circRNA_100290 in CRC. In summary, our study for the first time revealed a novel regulatory loop of circRNA_100290/miR-516b/FZD4/Wnt/β-catenin implicated in CRC progression.

Circular RNA circ-CBFB promotes proliferation and inhibits apoptosis in chronic lymphocytic leukemia through regulating miR-607/FZD3/Wnt/β-catenin pathway

Circular RNA (circRNA) belongs to the non-coding RNA family and is involved in various human cancers, such as lung cancer and colorectal cancer. Nevertheless, whether circRNA expression is related to chronic lymphocytic leukemia (CLL) progression remains largely unclear. In our study, we investigated the role of circ-CBFB in CLL. We found that circ-CBFB was markedly overexpressed in CLL cells compared to normal controls. Furthermore, we found that circ-CBFB could serve as a diagnostic and prognostic biomarker for CLL patients. We also explored the physiological function of circ-CBFB. We found that circ-CBFB knockdown significantly suppressed CLL cell proliferation, arrested cell cycle progression, and induced cellular apoptosis. In terms of its mechanism, we identified circ-CBFB as a sponge of miR-607, which targeted FZD3. By inhibiting miR-607 availability, circ-CBFB promoted FZD3 expression, leading to the activation of the Wnt/β-catenin pathway and consequent CLL progression. Taken together, our findings revealed that the circ-CBFB/miR-607/FZD3/Wnt/β-catenin regulatory signaling cascade contributes to CLL progression.