Bioinformatics analysis and experimental validation reveal the anti-ferroptosis effect of FZD7 in acute kidney injury

BACKGROUND

Ferroptosis plays an important role in acute kidney injury (AKI), but the specific regulatory mechanism of ferroptosis in AKI remains unclear. This study is expected to analyze ferroptosis-related genes (FRGs) in AKI and explore their underlying mechanisms.

RESULTS

A total of 479 differentially expressed genes (DEGs), including 196 up-regulated genes and 283 down-regulated genes were identified in the AKI chip GSE30718. 341 FRGs were obtained from the Genecard, OMIM and NCBI database. Totally 11 ferroptosis-related DEGs in AKI were found, in which 7 genes (CD44, TIGAR, RB1, LCN2, JUN, ARNTL, ACSL4) were up-regulated and 4 genes (FZD7, EP300, FOXC1, DLST) were down-regulated. Three core genes (FZD7, JUN, EP300) were obtained by PPI and KEGG analysis, among which the function of FZD7 in AKI is unclear. The WGCNA analysis found that FZD7 belongs to a module that was negatively correlated with AKI. Further basic experiments confirmed that FZD7 is down-regulated in mouse model of ischemia-reperfusion-AKI and cellular model of hypoxia-reoxygenation(H/R). In addition, knockdown of FZD7 could further aggravate the down-regulation of cell viability induced by H/R and Erastin, while overexpression of FZD7 can rescue its down-regulation to some extent. Furthermore, we verified that knockdown of FZD7 decreased the expression of GPX4 and overexpression of FZD7 increased the expression of GPX4, suggesting that FZD7 may inhibit ferroptosis by regulating the expression of GPX4 and plays a vital role in the onset and development of AKI.

CONCLUSIONS

This article revealed the anti-ferroptosis effect of FZD7 in acute kidney injury through bioinformatics analysis and experimental validation, suggesting that FZD7 is a promising target for AKI and provided more evidence about the vital role of ferroptosis in AKI.

The malignancy suppression and ferroptosis facilitation of BCL6 in gastric cancer mediated by FZD7 repression are strengthened by RNF180/RhoC pathway

BACKGROUND

B-cell lymphoma 6 (BCL6) is a transcription repressor that plays a tumor suppressor or promoting role in various tumors. However, its function and molecular mechanism in gastric cancer (GC) remain unclear. Ferroptosis, a novel programmed cell death, is closely related to tumor development. In this research, we aimed to explore the role and mechanism of BCL6 in malignant progression and ferroptosis of gastric cancer.

METHODS

Firstly, BCL6 was identified as an important biomarker that attenuated the proliferation and metastasis of GC through tumor microarrays and confirmed in GC cell lines. RNA sequence was performed to explore the downstream genes of BCL6. The underlying mechanisms were further investigated by ChIP, dual luciferase reporter assays and rescue experiments. Cell death, lipid peroxidation, MDA and Fe²⁺ level were detected to determine the effect of BCL6 on ferroptosis and the mechanism was revealed. CHX, MG132 treatment and rescue experiments were used to explore the upstream regulatory mechanism of BCL6.

RESULTS

Here we showed that BCL6 expression was significantly decreased in GC tissues, and patients with low BCL6 expression showed more malignant clinical features and poor prognosis. The upregulation of BCL6 may significantly inhibited the proliferation and metastasis of GC cells in vitro and in vivo. In addition, we found that BCL6 directly binds and transcriptionally represses Wnt receptor Frizzled 7 (FZD7) to inhibit the proliferation, metastasis of GC cells. We also found that BCL6 promoted lipid peroxidation, MDA and Fe²⁺ level to facilitate ferroptosis of GC cells by FZD7/β-catenin/TP63/GPX4 pathway. Furthermore, the expression and function of BCL6 in GC were regulated by the ring finger protein 180 (RNF180)/ras homolog gene family member C (RhoC) pathway, which had been elucidated to be involved in significantly mediating the proliferation and metastasis of GC cells.

CONCLUSIONS

In summary, BCL6 should be considered a potential intermediate tumor suppressor to inhibit the malignant progression and induce ferroptosis, which might be a promising molecular biomarker for further mechanistic investigation of GC.

NanoBiT- and NanoBiT/BRET-based assays allow the analysis of binding kinetics of WNT-3A to endogenous Frizzled 7 in a colorectal cancer model

BACKGROUND AND PURPOSE

WNT binding to Frizzleds (FZD) is a crucial step that leads to the initiation of signalling cascades governing multiple processes during embryonic development, stem cell regulation, and adult tissue homeostasis. Recent efforts have enabled us to shed light on WNT-FZD pharmacology in overexpressed HEK293 cells. However, assessing ligand binding at endogenous receptor expression levels is important as there might be differential binding behaviour in a native environment. Here, we study one FZD paralogue: FZD₇ , and analyze its interactions with WNT-3A in live CRISPR-Cas9-edited SW480 cells typifying colorectal cancer.

EXPERIMENTAL APPROACH

SW480 cells were CRISPR-Cas9-edited to insert a HiBiT-tag on the N-terminus of FZD₇ , preserving the native signal peptide. Subsequently, these cells were used to study eGFP-WNT-3A association with endogenous and overexpressed HiBiT-FZD₇ using NanoBiT/BRET and NanoBiT to measure ligand binding and receptor internalization.

KEY RESULTS

Using the newly developed assay, we detect the binding of eGFP-WNT-3A to endogenous HiBiT-FZD₇ and compare it with overexpressed receptors. We show that receptor overexpression results in increased membrane dynamics, leading to an apparent decrease in binding on-rate and consequently in higher, up to 10 times, calculated K_d . Thus, measurements of binding affinities of WNT-3A to FZD₇ obtained in overexpressed cells are suboptimal compared to the measurements from endogenously-expressing cells.

CONCLUSIONS AND IMPLICATIONS

Binding affinity measurements in the overexpressing cells fail to recapitulate ligand binding affinities assessed in a (patho-)physiologically relevant context where receptor expression is lower. Therefore, future studies on WNT-FZD₇ binding should be performed using receptors expressed under endogenous promotion.

FZD7, Regulated by Non-CpG Methylation, Plays an Important Role in Immature Porcine Sertoli Cell Proliferation

The regulatory role of non-CpG methylation in mammals has been important in whole-genome bisulfite sequencing. It has also been suggested that non-CpG methylation regulates gene expression to affect the development and health of mammals. However, the dynamic regulatory mechanisms of genome-wide, non-CpG methylation during testicular development still require intensive study. In this study, we analyzed the dataset from the whole-genome bisulfite sequencing (WGBS) and the RNA-seq of precocious porcine testicular tissues across two developmental stages (1 and 75 days old) in order to explore the regulatory roles of non-CpG methylation. Our results showed that genes regulated by non-CpG methylation affect the development of testes in multiple pathways. Furthermore, several hub genes that are regulated by non-CpG methylation during testicular development-such as VEGFA, PECAM1, and FZD7-were also identified. We also found that the relative expression of FZD7 was downregulated by the zebularine-induced demethylation of the first exon of FZD7. This regulatory relationship was consistent with the results of the WGBS and RNA-seq analysis. The immature porcine Sertoli cells were transfected with RNAi to mimic the expression patterns of FZD7 during testicular development. The results of the simulation test showed that cell proliferation was significantly impeded and that cell cycle arrest at the G2 phase was caused by the siRNA-induced FZD7 inhibition. We also found that the percentage of early apoptotic Sertoli cells was decreased by transfecting them with the RNAi for FZD7. This indicates that FZD7 is an important factor in linking the proliferation and apoptosis of Sertoli cells. We further demonstrated that Sertoli cells that were treated with the medium collected from apoptotic cells could stimulate proliferation. These findings will contribute to the exploration of the regulatory mechanisms of non-CpG methylation in testicular development and of the relationship between the proliferation and apoptosis of normal somatic cells.

An investigation of bacteriocin nisin anti-cancer effects and FZD7 protein interactions in liver cancer cells

The bacteriocin, nisin, produced by Lactococcus and Streptococcus species during fermentation, is widely used for bio preservatives in a wide variety of foods. Liver cancer has a high mortality rate and is the fourth leading cause of cancer-related deaths worldwide. Recently, researchers have shown the anti-cancer effects of nisin through in vitro and in vivo studies. This study aimed to investigate the effect of nisin on liver cancer cell lines, which represented two subgroups of the disease model. Nisin exhibited significant growth inhibition and apoptosis in both cell lines, HuH-7, and SNU182. Drug resistance is the main problem in liver cancer and the epithelial-to-mesenchymal transition has a role in the development of drug resistance in hepatocellular carcinoma. The expression of EMT transcription factors ZEB1, SNAI1, and TWIST1 were analyzed depending on nisin treatment, TWIST1 expression was down-regulated after nisin treatment compared to the untreated SNU182 and HuH-7 cell lines. Besides, due to the reported correlation between the overexpression of Frizzled (FZD) proteins, specifically FZD7, in primary hepatocellular carcinomas (HCCs), molecular docking was assessed for Nisin A in the binding site of FZD7. Results confirmed that Nisin A was able to form important hydrogen bonding with key residues. This research not only determined the role of nisin in different liver cancer cell models but it also provided the first result of FZD7 and nisin interaction.

FZD7 accelerates hepatic metastases in pancreatic cancer by strengthening EMT and stemness associated with TGF-β/SMAD3 signaling

Background

Metastasis of malignant tumors accelerates systemic failure and hastens the deaths of pancreatic cancer patients. During the metastatic process, the physical translocation of cancer cells from the primary lesion to distant organs and is crucial. CSCs properties, such as self-renewal and multiple-direction differentiation capacity are essential for colonization in the microenvironment of distant organs and metastatic lesion formation. It is widely believed that EMT can cause cancer cells to penetrate blood vessels by undergoing phenotypic and cytoskeletal changes, so that they can infiltrate surrounding tissue and disseminate from the primary tumor to the blood circulation, where they are termed circulating tumor cells (CTCs), while CTCs often exhibit stemness properties. Accumulating evidence demonstrates that some EMT-related transcription factors are essential for CSCs self-renewal, so cancer cells that have undergone EMT typically acquire increased stemness properties. Abnormal activation of the WNT signaling pathway can drive a series of gene transcripts to promote EMT in multiple types of cancer, and among different Frizzled receptors of WNT signaling pathway, FZD7 expression is associated with distant organ metastasis, advanced clinical stages, and poor clinical prognosis. Objective of this study is to demonstrate that high FZD7 expression in pancreatic cancer can accelerate hepatic metastases and elucidate the related molecular mechanisms.

Methods

The expression of Frrizled receptor 7 (FZD7) in pancreatic ductal adenocarcinoma (PDAC) and relating survival rate were analyzed by bioinformatics, histochemistry assay and follow-up study. In vitro, FZD7 expression was silenced by lentiviral vectors carrying short hair RNA (shRNA) or upregulated by overexpression plasmid. Then, Wound-healing and Transwell experiment was used to analyze the abilities of migration and invasion; the levels of epithelial-to-mesenchymal transition (EMT) relating phenotype proteins, stemness relating phenotype proteins, and signaling molecular proteins were measured by Western-blot; cell stemness was evaluated by sphere forming ability of cells in suspension culture and detecting the proportion of CD24⁺CD44⁺ cells with flow cytometry. TGF-β1 was used to induce EMT, and observe the effect of shRNA silencing FZD7 on which.

Results

High level of FZD7 expression in pancreatic cancer samples was associated with earlier hepatic metastasis. In vitro upregulation FZD7 can enable pancreatic cancer cells to obtain stronger migration and invasion ability and higher mesenchymal phenotype, and vice versa; the proportion of cancer stem cell (CSC) was also positively correlated with the level of FZD7; cells forming spheres in suspension culture showed stronger migration and invasion ability and higher level of mesenchymal phenotype than normal adherent cultured cells; the level of FZD7 was positively correlated with the level of activated β-catenin. Silencing FZD7 expression can attenuate EMT induced by TGF-β1 stimulating, and TGF-β1 stimulating can also upregulate stemness phenotype expression, such as ABCG2, CD24, and CD44 by mediating of FZD7.

Conclusions

High FZD7 expression in pancreatic cancer can accelerates hepatic metastases by promoting EMT and strengthening cell stemness, and FZD7 can work through the canonical Wingless-type (WNT) signaling pathway and participate in TGF-β/SMAD3 signaling pathway also.

CircRNA_Maml2 promotes the proliferation and migration of intestinal epithelial cells after severe burns by regulating the miR-93-3p/FZD7/Wnt/β-catenin pathway

Background

Circular RNA (circRNA) plays key regulatory roles in the development of many diseases. However the biological functions and potential molecular mechanisms of circRNA in the injury and repair of intestinal mucosa in mice after severe burns are yet to be elucidated.

Methods

Cell counting kit-8 (CCK-8), 5-ethynyl-2′-deoxyuridine (EdU), wound healing and transwell assays were used to detect cell proliferation and migration ability. Real-time quantitative PCR was used to identify the expression of circRNA, microRNA and messenger RNA. Nuclear and cytoplasmic separation experiments were employed to perceive the location of circRNA_Maml2. Finally, in vitro and in vivo experiments were conducted to study the repairing effect of circRNA_Maml2 on the intestinal mucosa of mice after severe burns.

Results

When compared with the control group, the expression of circRNA_Maml2 was significantly reduced in the severe burn group. Furthermore, overexpression of circRNA_Maml2 promoted the proliferation and migration of CT26.wt cells in vivo and the repair of damaged intestinal mucosa in vitro. CircRNA_Maml2 acted as a sponge adsorption molecule for miR-93-3p to enhance the expression of frizzled class receptor 7 and activate the downstream Wnt/β-catenin pathway, thereby promoting the repair of the intestinal mucosa.

Conclusions

Our findings demonstrate that circRNA_Maml2 regulates the miR-93-3p/FZD7/Wnt/β-catenin pathway and promotes the repair of damaged intestinal mucosa. Hence, circRNA_Maml2 is a potential therapeutic target to promote intestinal mucosal repair.

Circular RNA ACTN4 promotes intrahepatic cholangiocarcinoma progression by recruiting YBX1 to initiate FZD7 transcription

BACKGROUND & AIMS

Intrahepatic cholangiocarcinoma (ICC) is a primary liver cancer with high aggressiveness and extremely poor prognosis. The role of circular RNAs (circRNAs) in ICC carcinogenesis and progression remains to be determined.

METHODS

CircRNA microarray was performed to screen significantly upregulated circRNAs in paired ICC and non-tumor tissues. Colony formation, transwell, and xenograft models were used to examine the role of circRNAs in ICC proliferation and metastasis. RNA pulldown, mass spectrometry, chromatin immunoprecipitation, RNA-binding protein immunoprecipitation, chromatin isolation by RNA purification, electrophoretic mobility shift assay, and luciferase reporter assays were used to explore the molecular sponge role of the circRNA (via miRNA binding), and the interaction between circRNA and RNA-binding proteins.

RESULTS

Hsa_circ_0050898, which originated from exon 1 to exon 20 of the ACTN4 gene (named circACTN4), was significantly upregulated in ICC. High circACTN4 expression was associated with enhanced tumor proliferation and metastasis in vitro and in vivo, as well as a worse prognosis following ICC resection. In addition, circACTN4 upregulated Yes-associated protein 1 (YAP1) expression by sponging miR-424-5p. More importantly, circACTN4 also recruited Y-box binding protein 1 (YBX1) to stimulate Frizzled-7 (FZD7) transcription. Furthermore, circACTN4 overexpression in ICC cells enhanced the interaction between YAP1 and β-catenin, which are the core components of the Hippo and Wnt signaling pathways, respectively.

CONCLUSIONS

CircACTN4 was upregulated in ICC and promoted ICC proliferation and metastasis by acting as a molecular sponge of miR-424-5p, as well as by interacting with YBX1 to transcriptionally activate FZD7. These results suggest that circACTN4 is a potential prognostic marker and therapeutic target for ICC.

LAY SUMMARY

Intrahepatic cholangiocarcinoma is a primary liver cancer associated with aggressiveness and extremely poor prognosis. It is essential for therapeutic development that we uncover relevant pathogenic pathways. Herein, we showed that a circular RNA (circACTN4) was highly expressed in intrahepatic cholangiocarcinoma and was positively associated with tumor growth and metastasis through key developmental signaling pathways. Thus, circACTN4 could be a prognostic biomarker and therapeutic target for intrahepatic cholangiocarcinoma.

Frizzled7 Activates β-Catenin-Dependent and β-Catenin-Independent Wnt Signalling Pathways During Developmental Morphogenesis: Implications for Therapeutic Targeting in Colorectal Cancer

Frizzled₇ activates β-catenin-dependent and β-catenin-independent Wnt signalling pathways, is highly conserved through evolution from the ancient phylum hydra to man, plays essential roles in stem cells, tissue homeostasis and regeneration in the adult, and is upregulated in diverse cancers. Much of what is known about the core components of the Wnt signalling pathways was derived from studying the function of Frizzled₇ orthologues in the development of lower organism. As we interrogate Frizzled₇ signalling and function for therapeutic targeting in cancer, it is timely to revisit lower organisms to gain insight into the context dependent and dynamic nature of Wnt signalling for effective drug design.

Circular RNA circCSPP1 knockdown attenuates doxorubicin resistance and suppresses tumor progression of colorectal cancer via miR-944/FZD7 axis

BACKGROUND

Circular RNAs (circRNAs) have been reported to play vital roles in colorectal cancer (CRC). However, only a few circRNAs have been experimentally validated and functionally described. In this research, we aimed to reveal the functional mechanism of circCSPP1 in CRC.

METHODS

36 DOX sensitive and 36 resistant CRC cases participated in this study. The expression of circCSPP1, miR-944 and FZD7 were detected by quantitative real time polymerase chain reaction (qRT-PCR) and the protein levels of FZD7, MRP1, P-gp and LRP were detected by western blot. Cell proliferation, migration, invasion, and apoptosis were assessed by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay, transwell assay, or flow cytometry analysis, respectively. The interaction between miR-944 and circCSPP1 or frizzled-7 (FZD7) was predicted by Starbase 3.0 and verified by the dual luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull down assay. Xenograft tumor assay was performed to examine the effect of circCSPP1 on tumor growth in vivo.

RESULTS

The expression of circCSPP1 and FZD7 was upregulated while miR-944 expression was downregulated in doxorubicin (DOX)-resistant CRC tissues and cells. CircCSPP1 knockdown significantly downregulated enhanced doxorubicin sensitivity, suppressed proliferation, migration, invasion, and induced apoptosis in DOX-resistant CRC cells. Interestingly, we found that circCSPP1 directly downregulated miR-944 expression and miR-944 decreased FZD7 level through targeting to 3' untranslated region (UTR) of FZD7. Furthermore, circCSPP1 mediated DOX-resistant CRC cell progression and doxorubicin sensitivity by regulating miR-944/FZD7 axis. Besides, circCSPP1 downregulation dramatically repressed CRC tumor growth in vivo.

CONCLUSION

Our data indicated that circCSPP1 knockdown inhibited DOX-resistant CRC cell growth and enhanced doxorubicin sensitivity by miR-944/FZD7 axis, providing a potential target for CRC therapy.

LncRNA HOTAIR promotes breast cancer progression through regulating the miR-129-5p/FZD7 axis

Breast cancer is the most common malignancies worldwide. LncRNA HOX transcript antisense intergenic RNA (HOTAIR) has been shown to promote progression and metastasis of various cancers, including breast cancer. This reasearch aimed to investigate the downstream regulatory pathways of HOTAIR in breast cancer. The levels of HOTAIR and miR-129-5p were examined in breast cancer tissues and SKBR3 and MCF7 cells by quantitative real-time PCR (qRT-PCR). Cell proliferation was examined by Cell Counting Kit-8 (CCK-8) assay. Cell migration and invasion were estimated by transwell assay. Epithelial-to-mesenchymal transition (EMT)-related markers (E-cadherin, N-cadherin and Vimentin) were measured by Western blot assay. The expression of Frizzled 7 (FZD7) was detected using qRT-PCR or Western blot assay. Bioinformatics analysis, luciferase reporter assay or RNA Immunoprecipitation (RIP) assay was performed to explore the molecular mechanism of HOTAIR in breast cancer. Xenograft analysis was utilized to evaluate the tumor growth in vivo. HOTAIR and FZD7 were upregulated, while miR-129-5p was down-regulated in breast cancer tissues and cells. Knockdown of miR-129-5p reversed the effect of HOTAIR knockdown on cell proliferation, migration, invasion and EMT. FZD7 restored the inhibition of miR-129-5p on breast cancer progression. Furthermore, HOTAIR was a sponge of miR-129-5p and FZD7 was a target of miR-129-5p. Knockdown of HOTAIR inhibited the tumor growth in vivo. HOTAIR facilitated breast cancer progression by regulating the miR-129-5p/FZD7 axis, indicating that HOTAIR may be a potential biomarker and therapeutic target for breast cancer.

Targeting Oncogenic WNT Signalling with WNT Signalling-Derived Peptides

WNT signalling is known to be a crucial regulator of embryonic development and tissue homeostasis. Aberrant expression of WNT signalling elements or their mutations has been implicated in carcinogenesis and/or the progression of several different cancer types. Investigations of how WNT signalling affects carcinogenesis and cancer progression have revealed that it has essential roles in the regulation of proliferation, apoptosis, and cancer stemness and in angiogenesis and metastasis. Consequently, WNT-targeted therapy has gained much attention and has resulted in the development of several small molecules, the majority of which act as inhibitors of different WNT signalling events. However, although numerous inhibitory WNT signalling drug candidates have been included in clinical trials, no significant breakthroughs have been made. This could possibly be due to problems with inefficient binding to the target, compensatory signalling mechanisms and toxicity towards normal cells. Therapeutic peptides targeting WNT signalling in cancer cells have been developed as an alternative approach, with the hope that they might overcome the limitations reported for small WNT inhibitory molecules. In this chapter, we describe recent developments made in the design and characterization of WNT signalling-derived peptides aiming at their use as alternative cancer therapeutics and/or combined adjuvant therapy to conventional therapies.

MITF functions as a tumor suppressor in non-small cell lung cancer beyond the canonically oncogenic role

Microphthalamia-associated transcription factor (MITF) is a critical mediator in melanocyte differentiation and exerts oncogenic functions in melanoma progression. However, the role of MITF in non-small cell lung cancer (NSCLC) is still unknown. We found that MITF is dominantly expressed in the low-invasive CL1-0 lung adenocarcinoma cells and paired adjacent normal lung tissues. MITF expression is significantly associated with better overall survival and disease-free survival in NSCLC and serves as an independent prognostic marker. Silencing MITF promotes tumor cell migration, invasion and colony formation in lung adenocarcinoma cells. In xenograft mouse model, MITF knockdown enhances metastasis and tumorigenesis, but decreases angiogenesis in the Matrigel plug assay. Whole transcriptome profiling of the landscape of MITF regulation in lung adenocarcinoma indicates that MITF is involved in cell development, cell cycle, inflammation and WNT signaling pathways. Chromatin immunoprecipitation assays revealed that MITF targets the promoters of FZD7, PTGR1 and ANXA1. Moreover, silencing FZD7 reduces the invasiveness that is promoted by silencing MITF. Strikingly, MITF has significantly inverse correlations with the expression of its downstream genes in lung adenocarcinoma. In summary, we demonstrate the suppressive role of MITF in lung cancer progression, which is opposite to the canonical oncogenic function of MITF in melanoma.

Differential Wnt-β- catenin pathway activation in HPV positive and negative oral epithelium is transmitted during head and neck tumorigenesis: clinical implications

The aim of this study is to understand the association of HPV infection and wnt-β-catenin self-renewal pathway in development of head and neck squamous cell carcinoma (HNSCC). For this reason, the molecular profiles (methylation/deletion/expression) of antagonists (SFRP1/2 and DKK1), agonists (FZD7 and LRP6) and effector protein β-catenin of the pathway were analyzed in HPV positive/negative oral epithelium at first, followed by its changes during development of the tumor along with correlations with different clinico-pathological parameters. HPV infection alone or in combination with tobacco habit could activate p- β-catenin expression in basal/parabasal layers of oral epithelium through high expression of FZD7 and significant down regulation of SFRP1/2 through promoter hypermethylation due to over expression of DNMT1 with ubiquitous down regulation of DKK1 and up-regulation of LRP6. This phenomenon has been seen in respective HPV positive and negative HNSCC tumors with additional deletion/microsatellite size alterations in the antagonists. Overall alterations (methylation/deletion) of SFRP1/2, DKK1 gradually increased from Group I (HPV-/Tobacco-) to Group IV(HPV+/Tobacco+) tumors, leading to the worst prognosis of the patients. Thus, the transmission of differentially activated wnt-β-catenin pathway from HPV positive/negative basal/parabasal layers of oral epithelium to HNSCC tumors determines differences in molecular pathogenesis of the disease.

Regulation of ABCG2 expression by Wnt5a through FZD7 in human pancreatic cancer cells

ATP-binding cassette subfamily G member 2 (ABCG2), a member of the ABC transporter superfamily, has been implicated in the development of chemotherapeutic drug resistance in cancer cells. However, the regulators of ABCG2 expression and their roles in anticancer drug resistance have not been fully characterized, especially in the context of pancreatic cancer. The aim of the present study was to investigate whether ABCG2 contributed to drug resistance in pancreatic cancer and to elucidate its regulatory molecular pathways. Using immunohistochemical analysis of pancreatic ductal adenocarcinoma and adjacent healthy tissue samples, the present study identified a positive correlation between ABCG2 and Wnt5a, a member of the Wnt family of secreted proteins. It was also determined that treatment with recombinant human Wnt5a protein could upregulate the expression of ABCG2 in the Capan-2 human pancreatic cancer cell line and enhance its resistance to gemcitabine. The upregulation of ABCG2 by Wnt5a was inhibited by small interfering RNA silencing of Frizzled class receptor 7 (FZD7) or by FZD7 inhibitors. Moreover, both FZD7 silencing or inhibition of its function attenuated gemcitabine resistance induced by Wnt5a in Capan-2 cells. Therefore, the present findings suggested that Wnt5a and FZD7 acted as upstream regulators of ABCG2 expression and that FZD7 may be an essential factor for Wnt5a-induced gemcitabine resistance in pancreatic cancer cells.

Aberrant signal transduction in Indian triple-negative breast cancer patients

Aim of Study

The aim of this study is to correlate the prominin-1 or CD133 association with functional pathway markers of cancer stemness in Indian triple-negative breast cancer (TNBC) patient samples.

Materials and Methods

TNBC samples were confirmed for the absence of hormone receptors (estrogen receptor-ER/progesterone receptor) and human epidermal growth factor receptor-2 or proto-oncogene neu or erbB2 or CD340 by immunohistochemical analysis. Formalin-fixed paraffin-embedded samples of patients were used to collect the total RNA. Then, one-step reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the cancer stemness-related transcript levels in the different samples. The RT-PCR products were analyzed semi-quantitatively on agarose gels. The band intensities of respective samples for different transcripts were analyzed by densitometry.

Results

TNBC-confirmed samples had shown increased levels of CD133 transcript than control tissues. Further, elevated CD133 transcripts are correlated with higher transcript levels of NOTCH1/FZD7/transforming growth factor-beta receptor Type III R/patched-1 pathway mediators.

Conclusions

This work has clearly indicated that there is a correlation between CD133 and functional pathways that control cancer stem cells in TNBC. These observations may indicate the possible association between cancer stemness and TNBC malignancy.

Isolation and characterization of a new basal-like luminal progenitor in human breast tissue

Background

Adult stem cells and progenitors are responsible for breast tissue regeneration. Human breast epithelial progenitors are organized in a lineage hierarchy consisting of bipotent progenitors (BPs), myoepithelial- and luminal-restricted progenitors (LRPs) where the LRP differentiation into mature luminal cells requires estrogen receptor (ER) signaling. However, the experimental evidence exploring the relationship between the BPs and LRPs has remained elusive. In this study, we report the presence of a basal-like luminal progenitor (BLP) in human breast epithelial cells.

Methods

Breast reduction samples were used to obtain different subsets of human breast epithelial cell based on cell surface marker expression using flow cytometry. Loss of function and gain of function studies were employed to demonstrate the role of NOTCH3 (NR3)-FRIZZLED7 (FZD7) signaling in luminal cell fate commitment.

Results

Our results suggest that, NR3-FZD7 signaling axis was necessary for luminal cell fate commitment. Similar to LRPs, BLPs (NR3^highFZD7^highCD90⁺MUC1⁻ER⁻) differentiate to generate NR3^medFZD7^medCD90⁻MUC1⁺ER⁺ luminal cells. Unlike LRPs however, BLP’s proliferation and differentiation potentials depend on NR3 and regulated in part by FZD7 signaling. Lastly, we show that BLPs have a higher colony-forming potential than LRPs and that they are continuously generated from the NOTCH3⁻FZD7^low subset of the bipotent progenitors.

Conclusion

Our data indicate that BPs differentiate to generate basal-like luminal progenitors that in turn differentiate into LRPs. These results provide new insights into the hierarchical organization of human breast epithelial cell and how cooperation between the Notch and Wnt signaling pathways define a new progenitor cell type.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1361-3) contains supplementary material, which is available to authorized users.

miR-504 suppresses mesenchymal phenotype of glioblastoma by directly targeting the FZD7-mediated Wnt-β-catenin pathway

Background

MicroRNAs (miRNAs) play crucial roles in tumor initiation and development. Previously, we indicated that miR-504 is downregulated and suppresses tumor proliferation in glioblastoma (GBM). However, the regulation and relevant mechanism of miR-504 in GBM mesenchymal (ME) transition remain unclear.

Methods

Transcriptome and clinical data were obtained from The Cancer Genome Atlas (TCGA) database. The potential functions of miR-504 were predicted using gene ontology analysis. GBM cell migration and invasion were examined using wound healing and Transwell assays. Epithelial–mesenchymal transition (EMT) progression in GBM cell lines was detected with immunofluorescence and western blotting. The stemness activity of glioma stem-like cells (GSCs) was assessed by sphere formation assay and tumor xenograft model. miR-504 binding to the FZD7 (frizzled class receptor 7) 3′ untranslated region (3′UTR) was validated using dual luciferase reporter assay. TOP/FOP Flash assays were conducted to determine the effects of miR-504 on Wnt/β-catenin signaling.

Results

Analysis of TCGA transcriptomic data showed that low miR-504 expression correlated with ME subtype transition and poor survival in patients with GBM. Functional experiments showed that miR-504 overexpression suppressed malignant behaviors of GBM cells, such as migration, invasion, EMT, and stemness activity. Furthermore, miR-504 was a negative regulator of the Wnt–β-catenin pathway by directly repressing FZD7 expression, and FZD7 overexpression reversed the EMT inhibition caused by miR-504. Moreover, the low miR-504/FZD7 expression ratio was a ME subtype marker and could serve as a significant prognostic indicator and predict the clinical outcome of chemotherapy and radiotherapy for patients with GBM in TCGA dataset.

Conclusions

Our results suggest that miR-504 suppresses the aggressive biological processes associated with the ME phenotype of GBM and could be a potential candidate for therapeutic applications in these malignant brain tumors.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1370-1) contains supplementary material, which is available to authorized users.

MicroRNA-206 attenuates glioma cell proliferation, migration, and invasion by blocking the WNT/β-catenin pathway via direct targeting of Frizzled 7 mRNA

Glioma is one of the most prevalent primary malignant brain tumours among adults, and accumulating evidence has shown that dysregulation of microRNAs (miRNAs) is associated with various types of cancers, including glioma. It is necessary to gain a better understanding of the roles and mechanisms of action of miRNAs in WNT-driven glioblastoma multiforme (GBM). Here, we report that miR-206 inhibits the WNT/β-catenin pathway by directly targeting Frizzled 7 (FZD7) mRNA and functions as a tumour suppressor in glioma. The expression of miR-206 in human glioma samples and glioma cells was assessed by reverse-transcription quantitative PCR, fluorescence in situ hybridisation, and histological analysis. Cell Counting Kit-8, colony formation, 5-ethynyl-2'-deoxyuridine incorporation, flow-cytometric, wound healing, Transwell invasion, and three-dimensional migration assays were performed to examine glioma cell proliferation, migration, and invasion in vitro. The effects of miR-206 in vivo were investigated in a xenograft nude-mouse model. MiR-206 expression was significantly lower in glioma specimens than in normal control samples. FZD7 was confirmed as a direct target gene of miR-206. GBM cell proliferation, migration, and invasion were blocked after restoration of miR-206 expression. Moreover, intracranial glioma models revealed an inhibitory effect of miR-206 on intracranial glioma tumour growth. Our results suggest that miR-206 plays a key role in the blockade of the WNT/β-catenin signalling pathway by down-regulating FZD7 and may be a promising therapeutic agent against malignant glioma and other WNT-driven tumours.

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.

MicroRNA-488 inhibits endometrial glandular epithelial cell proliferation, migration, and invasion in endometriosis mice via Wnt by inhibiting FZD7

Endometriosis is a chronic inflammatory syndrome and nearly 6%‐10% of women are affected by it during the reproductive period. Previous studies have proved that microRNAs (miRNAs) are implicated in the pathogenesis of ovarian endometriosis. In this study, we aimed to investigate that restored miR‐488 would effectively inhibit the development of endometriosis. The microarray‐based data analysis was performed to screen endometriosis‐related differentially expressed genes (DEGs). The mouse model in endometriosis syndrome was established by being subcutaneously injected with Estradiol benzoate, and the ectopic endometrial tissues and normal endometrial tissues were collected. Additionally, the endometrial glandular epithelial cells were extracted from the endometrial glandular epithelial tissues from normal and endometriosis mice. In order to examine the role of miR‐488 in mice with endometriosis, we measured miR‐488 expression and expression levels of Frizzled‐7 (FZD7), cyclinD1, β‐catenin, and c‐Myc in vivo and in vitro. Finally, we detected the effect of miR‐488 on cell proliferation, apoptosis, migration and invasion in vitro. FZD7 was upregulated in human endometriosis. The data showed higher expression levels of FZD7, β‐catenin, c‐Myc and cyclinD1, and lower miR‐488 expression in mouse endometrial tissues. FZD7 was the target gene of miR‐488. Furthermore, elevated miR‐488 in isolated mouse endometrial glandular endometrial cells inhibited FZD7, the translocation of β‐catenin to nucleus, the activation of Wnt pathway, and the cell proliferation, migration and invasion. Collectively, these findings indicated that up‐regulated miR‐488 may reduce the proliferation, migration and invasion of endometrial glandular epithelial cells through inhibiting the activation of Wnt pathway by down‐regulating FZD7.

The FZD7-TWIST1 axis is responsible for anoikis resistance and tumorigenesis in ovarian carcinoma

Frizzled family receptor 7 (FZD7), a Wnt signaling receptor, is associated with the maintenance of stem cell properties and cancer progression. FZD7 has emerged as a potential therapeutic target because it is capable of transducing both canonical and noncanonical Wnt signals. In this study, we investigated the regulatory pathway downstream of FZD7 and its functional roles. We found that FZD7 expression was crucial to the maintenance of the mesenchymal phenotype, anoikis resistance, and spheroid and tumor formation in ovarian cancer (OC). We identified TWIST1 as the crucial downstream effector of the FZD7 pathway. TWIST1, a basic helix loop helix transcription factor, is known to associate with mesenchymal and cancer stem cell phenotypes. Manipulating TWIST1 expression mimicked the functional consequences observed in the FZD7 model, and overexpression of TWIST1 partially rescued the functional phenotypes abolished by FZD7 knockdown. We further proved that FZD7 regulated TWIST1 expression through epigenetic modifications of H3K4me3 and H3K27ac at the TWIST1 proximal promoter. We also identified that the FZD7‐TWIST1 axis regulates the expression of BCL2, a gene that controls apoptosis. Identification of this FZD7‐TWIST1‐BCL2 pathway reaffirms the mechanism of anoikis resistance in OC. We subsequently showed that the FZD7‐TWIST1 axis can be targeted by using a small molecule inhibitor of porcupine, an enzyme essential for secretion and functional activation of Wnts. In conclusion, our results identified that the FZD7‐TWIST1 axis is important for tumorigenesis and anoikis resistance, and therapeutic inhibition results in cell death in OCs.

MicroRNA-504 functions as a tumor suppressor in hepatocellular carcinoma through inhibiting Frizzled-7-mediated-Wnt/β-catenin signaling

Accumulating evidence suggests that microRNAs (miRNAs) are critical regulators in the development and progression of various malignant tumors, including hepatocellular carcinoma (HCC). Multiple findings have indicated that miRNA-504 (miR-504) is dysregulated in several types of cancers, functioning as an oncogenic miRNA or a tumor suppressive miRNA. However, the role of miR-504 in HCC remains unknown. In this study, we aimed to detect the expression pattern of miR-504 in HCC tissues and cell lines and investigate the precise biological function in HCC cells. Our results showed that miR-504 expression levels were frequently downregulated in both HCC tissues and cell lines. Gain-of-function experiments demonstrated that miR-504 overexpression inhibited the proliferation and invasion in HCC cell lines. By contrast, miR-504 inhibition had the opposite effect. Interestingly, bioinformatics analysis predicted that Frizzled-7 (FZD7) was a potential target gene of miR-504. Dual-luciferase reporter assays confirmed that miR-504 directly targeted the 3'-untranslated region of FZD7 mRNA. In addition, our results showed that miR-504 negatively regulated the mRNA and protein expression of FZD7 in HCC cell lines. Moreover, miR-540 overexpression inhibited the cellular expression of β-catenin and blocked the activation of Wnt signaling in HCC cells. Notably, restoration of FZD7 expression significantly reversed the inhibitory effect of miR-504 on proliferation, invasion, and Wnt/β-catenin signaling in HCC cells. In conclusion, our results demonstrate that miR-504 functions as a tumor suppressive miRNA that inhibits the proliferation and invasion of HCC cells by targeting FZD7 and inhibiting Wnt/β-catenin signaling. Our study provides evidence that miR-504-meidated FZD7/Wnt/β-catenin signaling pathway plays an important role in HCC development and progression and suggests miR-504 as a novel future therapeutic target for treatment of HCC.

Overexpression of FZD7 promotes glioma cell proliferation by upregulating TAZ

Gliomas are the most prevalent type of primary brain tumors in adults, accounting for more than 40% of neoplasm in the central nervous system. Frizzled-7 (FZD7) is a seven-pass trans-membrane Wnt receptor that plays a critical role in the development of various tumors. In this study, we detected high-level FZD7 expression in glioma and its overexpression was associated with advanced tumor stage. In vitro functional assays showed that forced overexpression of FZD7 promoted proliferation of gliomas cells, whereas knockdown of endogenous FZD7 significantly suppressed proliferation ability of these cells. In a xenograft assay, FZD7 was also found to promote the growth of glioma cells. We further found that FZD7 could activate transcriptional coactivator with PDZ-binding motif (TAZ), and TAZ was required for FZD7 to promote cell proliferation in glioma. Furthermore, the univariate analysis of survival shows that glioma patients with high FZD7 expression have a shorter survival. In conclusion, our findings demonstrate that FZD7 may promote glioma cell proliferation via upregulation of TAZ.

Frizzled7 Promotes Epithelial-to-mesenchymal Transition and Stemness Via Activating Canonical Wnt/β-catenin Pathway in Gastric Cancer

Aberrant activation of Wnt signaling is a crucial event in tumor development and metastasis. Wnt signaling is commonly divided into canonical and non-canonical signaling pathways based on whether β-catenin is activated (canonical). The two signaling pathways are initiated by Wnt ligand binding to the surface Frizzled (FZD) receptors, and regulate cancer stem cell self-renewal and epithelial-mesenchymal transition (EMT). Frizzled 7 (FZD7), a member of Frizzled family, promotes cell proliferation and invasiveness in many cancers, suggesting that FZD7 transmitting Wnt signaling is important for driving cancer growth. FZD7 expression has been reported to be up-regulated in human primary gastric cancer tissues. However, the molecular mechanism by which FZD7 promotes gastric cancer(GC) development and progression is not fully understood. Our present study showed that FZD7 was overexpressed in clinical GC samples, and thus was correlated with tumor invasion, lymphatic and organ metastasis, late TNM stages and poor patient survival. The endogenous expression of FZD7 was significantly increased in cancer stem cell-enriched spheres compared with adherent cells. Furthermore, RNA interference-mediated silencing of FZD7 inhibited proliferation, migration and invasion in gastric cancer cells. Moreover, ablation of FZD7 down-regulated EMT and the expression levels of cancer stem cell markers, and these inhibitions were associated with attenuated canonical Wnt/β-catenin signaling. The results suggest that Wnt canonical pathway may contribute to tumorigenesis and metastasis, indicating that FZD7 could be a potential therapeutic target for gastric cancer.

FZD7 is a novel prognostic marker and promotes tumor metastasis via WNT and EMT signaling pathways in esophageal squamous cell carcinoma

Frizzled (FZD) proteins are receptors for secreted WNT proteins and play a critical role in the malignant progression of various cancers. However, the role of human FZD family members in esophageal squamous cell carcinoma (ESCC) was rarely investigated. In this study, we found that the FZD7 gene was the most commonly up-regulated FZD member in ESCC cell lines compared with other FZDs. TMA studies further validated that FZD7 protein was up-regulated in 165 of 252 (65.5%) informative ESCC patients and significantly correlated with poor overall survival (P=0.001). Additionally, multivariate Cox regression analysis showed that FZD7 overexpression was an independent prognostic factor for ESCC patients. Ectopic expression of FZD7 could promote ESCC cell metastasis both in vitro and in vivo. Under WNT3A stimulation, FZD7 was able to induce the nuclear translocation of β-catenin and activate the downstream targets of WNT/β-catenin signaling, as well as promote epithelial-mesenchymal transition (EMT) potential in ESCC cells. Our study demonstrated for the first time that FZD7 contributes to the malignant progression of ESCC and represents a novel prognostic marker and a potential therapeutic target for ESCC patients.

MicroRNA-27b inhibits cell proliferation in oral squamous cell carcinoma by targeting FZD7 and Wnt signaling pathway

This study intended to investigate the role of microRNA-27b (miR-27b) in proliferation of oral squamous cell carcinoma (OSCC) cells and to explore the potential molecular mechanism. Cell proliferation was detected by MTT assay. The expression levels of miR-27b, Frizzled7 (FZD7), cyclin D1 and c-myc were detected by quantitative real time polymerase chain reaction (qRT-PCR). The protein expression level of FZD7 was detected by western blot analysis. The relationship between miR-27b and FZD7, and the activity of Wnt signaling pathway were determined using luciferase reporter assay. The miR-27b expression in OSCC cell lines was significantly decreased compared with control. Overexpression of miR-27b remarkably inhibited OSCC cell proliferation. Additionally, miR-27b could target and inhibit FZD7 expression and decrease the activity of Wnt signaling pathway.miR-27b could inhibit OSCC cell proliferation through inhibiting FZD7 and FZD7-mediated Wnt signaling pathway.

FZD7 regulates BMSCs-mediated protection of CML cells

Inspite of effective treatment with imatinib (IM), chronic myeloid leukemia (CML) is still an incurable disease. Some patients became refractory because of IM resistance. Bone marrow mesenchymal stem cells (BMSCs) have been implicated a role in promoting CML cells' resistance against IM treatment. The detailed molecular mechanisms, however, remain largely unknown. In this study, we found that BMSCs increased the expression of FZD7 and activated Wnt/β-catenin signaling pathway in CML cells. BMSCs from CML patients showed increased efficiency to accelerate CML cell proliferation, enhance the drug resistance of K562 cells and up-regulate the expression of FZD7. Antagonism of FZD7 expression by shRNA significantly suppressed proliferation and increased IM sensitivity of CML cells co-cultured with BMSCs cells. Our findings suggest that FZD7, involved in canonical Wnt signaling pathway, plays a critical role in mediating BMSCs-dependent protection of CML cells, and potentially provide a novel therapeutic target for CML.

MicroRNA-542-3p inhibits the growth of hepatocellular carcinoma cells by targeting FZD7/Wnt signaling pathway

MicroRNAs (miRNA) are relevant regulators of the tumorigenesis of various cancers, such as hepatocellular carcinoma (HCC). Recent studies have suggested that miR-542-3p is a tumor suppressor gene in numerous cancers. However, the role of miR-542-3p in HCC remains unclear. This study showed that miR-542-3p was downregulated in HCC tissues and cell lines. MTT, colony formation, and cell cycle assays revealed that miR-542-3p overexpression inhibited HCC cell growth, whereas miR-542-3p suppression promoted cell growth. Frizzled7 (FZD7), the most important Wnt receptor involved in cancer development and progression, was identified as a functional target of miR-542-3p through dual-luciferase reporter assay, RT-qPCR, and Western blot. The mRNA expression of FZD7 was inversely correlated with miR-542-3p expression in HCC tissues. miR-542-3p overexpression could significantly decrease the activation of Wnt signaling pathway in HCC cells. FZD7 overexpression could significantly reverse the inhibitory effect of miR-542-3p on HCC cell growth and Wnt signaling pathway. Taken together, our study suggests that miR-542-3p inhibits HCC cell growth by targeting FZD7 and inhibiting Wnt signaling pathway. The decreased miR-542-3p expression may also contribute to the progression of HCC and may represent a novel molecular therapeutic target for HCC.

Frizzled7: A Promising Achilles' Heel for Targeting the Wnt Receptor Complex to Treat Cancer

Frizzled7 is arguably the most studied member of the Frizzled family, which are the cognate Wnt receptors. Frizzled7 is highly conserved through evolution, from Hydra through to humans, and is expressed in diverse organisms, tissues and human disease contexts. Frizzled receptors can homo- or hetero-polymerise and associate with several co-receptors to transmit Wnt signalling. Notably, Frizzled7 can transmit signalling via multiple Wnt transduction pathways and bind to several different Wnt ligands, Frizzled receptors and co-receptors. These promiscuous binding and functional properties are thought to underlie the pivotal role Frizzled7 plays in embryonic developmental and stem cell function. Recent studies have identified that Frizzled7 is upregulated in diverse human cancers, and promotes proliferation, progression and invasion, and orchestrates cellular transitions that underscore cancer metastasis. Importantly, Frizzled7 is able to regulate Wnt signalling activity even in cancer cells which have mutations to down-stream signal transducers. In this review we discuss the various aspects of Frizzled7 signalling and function, and the implications these have for therapeutic targeting of Frizzled7 in cancer.

RNA-seq reveals determinants for irinotecan sensitivity/resistance in colorectal cancer cell lines

Irinotecan is a topoisomerase I inhibitor approved worldwide as a first- and second-line chemotherapy for advanced or recurrent colorectal cancer (CRC). Although irinotecan showed significant survival advantage for patients, a relatively low response rate and severe adverse effects demonstrated the urgent need for biomarkers searching to select the suitable patients who can benefit from irinotecan-based therapy and avoid the adverse effects. In present work, the irinotecan response (IC50 doses) of 20 CRC cell lines were correlated with the basal expression profiles investigated by RNA-seq to figure out genes responsible for irinotecan sensitivity/resistance. Genes negatively or positively correlated to irinotecan sensitivity were given after biocomputation, and 7 (CDC20, CTNNAL1, FZD7, CITED2, ABR, ARHGEF7, and RNMT) of them were validated in two CRC cell lines by quantitative real-time PCR, several of these 7 genes has been proposed to promote cancer cells proliferation and hence may confer CRC cells resistance to irinotecan. Our work might provide potential biomarkers and therapeutic targets for irinotecan sensitivity in CRC cells.

MiR-27a modulates the MDR1/P-glycoprotein expression by inhibiting FZD7/β-catenin pathway in hepatocellular carcinoma cells

Chemotherapy has been widely used to treat cancer, however, the appearance of multiple drug resistance (MDR) in cancer patients is regarded as a major clinical obstacle to successful chemotherapy. MicroRNAs (miRNAs) are evolutionary conserved small RNAs that regulate gene expression at the post-transcriptional level and have been shown to regulate cell differentiation, development, proliferation and apoptosis. Nevertheless, the involvement of miRNAs and their roles in the development of MDR in liver cancer are not fully understood. Our study found that the expression of miR-27a was down-regulated in the multidrug-resistant hepatocellular carcinoma cell line BEL-7402/5-fluorouracil (BEL/5-FU) compared with its parental BEL-7402 cell line, while the MDR1/P-glycoprotein expression was elevated. Overexpression of miR-27a by transfecting with miR-27a mimics in the BEL/5-FU cells could reduce the MDR1/P-glycoprotein and β-catenin expressions, enhance the sensitivity of these cells to 5-fluorouracil and 5-fluorouracil-induced apoptosis. Moreover, up-regulation of miR-27a did not decrease the FZD7 mRNA level, but significantly reduce its protein expression in BEL/5-FU cells. It was also confirmed that reduction of FZD7 by RNA interference induced inhibitory effects on the expression of MDR1/P-glycoprotein and β-catenin, similar to miR-27a. Taken together, our findings suggest that miR-27a could function as a novel regulator to reverse MDR in hepatocellular carcinoma cells by inhibiting the FZD7/β-catenin pathway.