Elevated CRB3 expression suppresses breast cancer stemness by inhibiting β-catenin signalling to restore tamoxifen sensitivity

Fructose-bisphosphatase1 (FBP1) alleviates experimental osteoarthritis by regulating Protein crumbs homolog 3 (CRB3)

PURPOSE

To identify the role of gluconeogenesis in chondrocytes in osteoarthritis (OA).

MATERIALS AND METHODS

Cartilage samples were collected from OA patients and C57 mice and were stained with Safranin O-Fast Green to determine the severity of OA. Periodic acid Schiff staining was used to characterize the contents of polysaccharides and SA-βGal staining was used to characterize the aging of chondrocytes. Immunohistochemistry and western blotting were used to detect fructose-bisphosphatase1 (FBP1), SOX9, MMP13, P21, and P16 in cartilage or chondrocyte. The mRNA levels of fbp1, mmp13, sox9, colX, and acan were analyzed by qPCR to evaluate the role of FBP1 in chondrocytes.

RESULTS

The level of polysaccharides in cartilage was reduced in OA and the expression of FBP1 was also reduced. We treated the chondrocytes with IL-1β to cause OA in vitro, and then made chondrocytes overexpress FBP1 with plasma. It shows that FBP1 alleviated the degeneration and senescence of chondrocytes in vitro and that it also showed the same effects in vivo experiments. To further understand the mechanism of FBP1, we screened the downstream protein of FBP1 and found that CRB3 was significantly downregulated. And we confirmed that CRB3 suppressed the degeneration and delayed senescence of chondrocytes.

CONCLUSIONS

FBP1 promoted the polysaccharide synthesis in cartilage and alleviated the degeneration of cartilage by regulating CRB3, so FBP1 is a potential target in treating OA.

Genome editing approaches with CRISPR/Cas9: the association of NOX4 expression in breast cancer patients and effectiveness evaluation of different strategies of CRISPR/Cas9 to knockout Nox4 in cancer cells

BACKGROUND

The increasing prevalence of cancer detection necessitated practical strategies to deliver highly accurate, beneficial, and dependable processed information together with experimental results. We deleted the cancer biomarker NOX4 using three novel genetic knockout (KO) methods. Homology-directed repair (HDR), Dual allele HITI (Du-HITI) and CRISPR-excision were utilized in this study.

METHODS

The predictive value of the NOX4 expression profile was assessed using a combined hazard ratio (HR) with a 95% confidence interval (CI). With a 95% confidence interval, a pooled odd ratio (OR) was used to calculate the relationship between NOX4 expression patterns and cancer metastasis. There were 1060 tumor patients in all sixteen research that made up this meta-analysis. To stop the NOX4 from being transcribed, we employed three different CRISPR/Cas9-mediated knockdown methods. The expression of RNA was assessed using RT-PCR. We employed the CCK-8 assay, colony formation assays, and the invasion transwell test for our experiments measuring cell proliferation and invasion. Using a sphere-formation test, the stemness was determined. Luciferase reporter tests were carried out to verify molecular adhesion. Utilizing RT-qPCR, MTT, and a colony formation assay, the functional effects of NOX4 genetic mutation in CRISPR-excision, CRISPR-HDR, and CRISPR du-HITI knockdown cell lines of breast cancer were verified.

RESULTS

There were 1060 malignant tumors in the 16 studies that made up this meta-analysis. In the meta-analysis, higher NOX4 expression was linked to both a shorter overall survival rate (HR = 1.93, 95% CI 1.49-2.49, P < 0.001) and a higher percentage of lymph node metastases (OR = 3.22, 95% CI 2.18-4.29, P < 0.001). In breast carcinoma cells, it was discovered that NOX4 was overexpressed, and this increase was linked to a poor prognosis. The gain and loss-of-function assays showed enhanced NOX4 breast carcinoma cell proliferation, sphere-forming capacity, and tumor development. To activate transcription, the transcriptional factor E2F1 also attaches to the promoter region of the Nanog gene. The treatment group (NOX4 ablation) had substantially more significant levels of proapoptotic gene expression than the control group (P < 0.01). Additionally, compared to control cells, mutant cells expressed fewer antiapoptotic genes (P < 0.001). The du-HITI technique incorporated a reporter and a transcription termination marker into the two target alleles. Both donor vector preparation and cell selection were substantially simpler using this approach than with "CRISPR HDR" or "CRISPR excision." Furthermore, single-cell knockouts for both genotypes were created when this method was applied in the initial transfection experiment.

CONCLUSIONS

The NOX4 Knockout cell lines generated in this research may be used for additional analytical studies to reveal the entire spectrum of NOX4 activities. The du-HITI method described in this study was easy to employ and could produce homozygous individuals who were knockout for a specific protein of interest.

CRB3 navigates Rab11 trafficking vesicles to promote γTuRC assembly during ciliogenesis

The primary cilium plays important roles in regulating cell differentiation, signal transduction, and tissue organization. Dysfunction of the primary cilium can lead to ciliopathies and cancer. The formation and organization of the primary cilium are highly associated with cell polarity proteins, such as the apical polarity protein CRB3. However, the molecular mechanisms by which CRB3 regulates ciliogenesis and the location of CRB3 remain unknown. Here, we show that CRB3, as a navigator, regulates vesicle trafficking in γ-tubulin ring complex (γTuRC) assembly during ciliogenesis and cilium-related Hh and Wnt signaling pathways in tumorigenesis. Crb3 knockout mice display severe defects of the primary cilium in the mammary ductal lumen and renal tubule, while mammary epithelial-specific Crb3 knockout mice exhibit the promotion of ductal epithelial hyperplasia and tumorigenesis. CRB3 is essential for lumen formation and ciliary assembly in the mammary epithelium. We demonstrate that CRB3 localizes to the basal body and that CRB3 trafficking is mediated by Rab11-positive endosomes. Significantly, CRB3 interacts with Rab11 to navigate GCP6/Rab11 trafficking vesicles to CEP290, resulting in intact γTuRC assembly. In addition, CRB3-depleted cells are unresponsive to the activation of the Hh signaling pathway, while CRB3 regulates the Wnt signaling pathway. Therefore, our studies reveal the molecular mechanisms by which CRB3 recognizes Rab11-positive endosomes to facilitate ciliogenesis and regulates cilium-related signaling pathways in tumorigenesis.

CRISPR/Cas9-mediated LINC00511 knockout strategies, increased apoptosis of breast cancer cells via suppressing antiapoptotic genes

Background

The growing detection of long noncoding RNAs (lncRNAs) required the application of functional approaches in order to provide absolutely precise, conducive, and reliable processed information along with effective consequences. We utilized genetic knockout (KO) techniques to ablate the Long Intergenic Noncoding RNA 00,511 gene in several humans who suffered from breast cancer cells and at the end we analyzed and examined the results.

Results

The predictive relevance of LINC00511 expression pattern was measured by using a pooled hazard ratio (HR) with a 95% confidence interval (CI). The link among LINC00511 expression profiles and cancer metastasis was measured by using a pooled odds ratio (OR) with a 95% confidence interval. This meta- analysis was composed of fifteen studies which contained a total of 1040 tumor patients. We used three distinct CRISPR/Cas9-mediated knockdown techniques to prevent the LINC00511 lncRNA from being transcribed. RT-PCR was used to measure lncRNA and RNA expression. We used CCK-8, colony formation tests, and the invasion transwell test to measure cell proliferation and invasion. The stemness was measured by using a sphere-formation test. To validate molecular attachment, luciferase reporter assays were performed. The functional impacts of LINC00511 gene deletion in knockdown breast cancer cell lines were confirmed by using RT-qPCR, MTT, and a colony formation test. This meta-analysis was composed of 15 trials which contained a total of 1040 malignant tumors. Greater LINC00511 expression was ascribed to a lower overall survival (HR = 1.93, 95% CI 1.49–2.49, < P 0.001) and to an increased proportion of lymph node metastasis (OR = 3.07, 95% CI 2.23–4.23, P < 0.001) in the meta‐analysis. It was found that the role of LINC00511 was overexpressed in breast cancer samples, and this overexpression was ascribed to a poor prognosis. The gain and loss-of-function tests demonstrated findings such as LINC00511 increased breast cancer cell proliferation, sphere-forming ability, and tumor growth. Additionally, the transcription factor E2F1 binds to the Nanog gene's promoter site to induce transcription. P57, P21, Prkca, MDM4, Map2k6, and FADD gene expression in the treatment group (LINC00511 deletion) was significantly higher than in the control group (P < 0.01). In addition, knockout cells had lower expression of BCL2 and surviving genes than control cells P < 0.001). In each of the two target alleles, the du-HITI approach introduced a reporter and a transcription termination signal. This strategy's donor vector preparation was significantly easier than "CRISPR HDR," and cell selection was likewise much easier than "CRISPR excision." Furthermore, when this approach was used in the initial transfection attempt, single-cell knockouts for both alleles were generated.

Conclusions

The methods employed and described in this work could be extended to the production of LINC00511 knockout cell lines and, in theory, to the deletion of other lncRNAs to study their function.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12575-022-00171-1.

Knockdown of ATG4A inhibits breast cancer progression and promotes tamoxifen chemosensitivity by suppressing autophagy

Autophagy-related 4A (ATG4A) is an autophagy regulator. The current study investigated the role of ATG4A in the development of tamoxifen-resistant breast cancer. ATG4A expression was assessed in tumor and adjacent normal tissue obtained from The Cancer Genome Atlas database. Analyses of the disease-free survival between the ATG4A high and low expression groups was then evaluated in patients with breast cancer. Cell viability and apoptosis in MCF7/R cells was detected using Cell Counting Kit-8 assay and flow cytometry, respectively. Gene set enrichment analysis identified the pathway responsible for the effects of ATG4A. The protein expression of ATG4A, LC3, p62, Bcl-2, Bax, GSK-3β, phosphorylated (p)-GSK-3β, β-catenin, cyclinD1 and c-myc in MCF and MCF7/R cells was determined using western blot. In this study, ATG4A expression was increased in the tumor tissues, and a higher ATG4A expression exhibited poor disease-free survival. While 4-hydroxytamoxifen (4-OHT) increased ATG4A expression in MCF7 and MCF7/R cells, ATG4A expression decreased in the cells treated with 3-methyladenine (3MA). Treatment with 4-OHT and rapamycin (an autophagy activator) increased the LC3-II/LC3-I ratio, LC3 puncta number and decreased the level of p62 in MCF7/R cells. However, the effects of 4-OHT and rapamycin were reversed by 3MA and knockdown of ATG4A, respectively. After treatment with 4-OHT, knockdown of ATG4A suppressed proliferation, triggered apoptosis, decreased the expression of Bcl-2, β-catenin, cyclin D1 and c-myc, and increased the expression of Bax and p-GSK3β in MCF7/R cells. Moreover, SKL2001, an activator of the Wnt/β-catenin signaling pathway, reversed the effects of ATG4A knockdown on cell viability and apoptosis in MCF7/R cells. In conclusion, the knockdown of ATG4A inhibited the anticancer effects of 4-OHT in breast cancer.

METTL3 promotes colorectal carcinoma progression by regulating the m6A-CRB3-Hippo axis

Background

Colorectal carcinoma (CRC) is the third most common cancer and second most common cause of cancer-related deaths worldwide. Ribonucleic acid (RNA) N6-methyladnosine (m6A) and methyltransferase-like 3 (METTL3) play key roles in cancer progression. However, the roles of m6A and METTL3 in CRC progression require further clarification.

Methods

Adenoma and CRC samples were examined to detect m6A and METTL3 levels, and tissue microarrays were performed to evaluate the association of m6A and METTL3 levels with the survival of patients with CRC. The biological functions of METTL3 were investigated through cell counting kit-8, wound healing, and transwell assays. M6A epitranscriptomic microarray, methylated RNA immunoprecipitation-qPCR, RNA stability, luciferase reporter, and RNA immunoprecipitation assays were performed to explore the mechanism of METTL3 in CRC progression.

Results

M6A and METTL3 levels were substantially elevated in CRC tissues, and patients with CRC with a high m6A or METTL3 levels exhibited shorter overall survival. METTL3 knockdown substantially inhibited the proliferation, migration, and invasion of CRC cells. An m6A epitranscriptomic microarray revealed that the cell polarity regulator Crumbs3 (CRB3) was the downstream target of METTL3. METTL3 knockdown substantially reduced the m6A level of CRB3, and inhibited the degradation of CRB3 mRNA to increase CRB3 expression. Luciferase reporter assays also showed that the transcriptional level of wild-type CRB3 significantly increased after METTL3 knockdown but not its level of variation. Knockdown of YT521-B homology domain–containing family protein 2 (YTHDF2) substantially increased CRB3 expression. RNA immunoprecipitation assays also verified the direct interaction between the YTHDF2 and CRB3 mRNA, and this direct interaction was impaired after METTL3 inhibition. In addition, CRB3 knockdown significantly promoted the proliferation, migration, and invasion of CRC cells. Mechanistically, METTL3 knockdown activated the Hippo pathway and reduced nuclear localization of Yes1-associated transcriptional regulator, and the effects were reversed by CRB3 knockdown.

Conclusions

M6A and METTL3 levels were substantially elevated in CRC tissues relative to normal tissues. Patients with CRC with high m6A or METTL3 levels exhibited shorter overall survival, and METTL3 promoted CRC progression. Mechanistically, METTL3 regulated the progression of CRC by regulating the m6A–CRB3–Hippo pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02227-8.

Immune Cell Infiltration-Based Characterization of Triple-Negative Breast Cancer Predicts Prognosis and Chemotherapy Response Markers

Breast cancer represents the number one cause of cancer-associated mortality globally. The most aggressive molecular subtype is triple negative breast cancer (TNBC), of which limited therapeutic options are available. It is well known that breast cancer prognosis and tumor sensitivity toward immunotherapy are dictated by the tumor microenvironment. Breast cancer gene expression profiles were extracted from the METABRIC dataset and two TNBC clusters displaying unique immune features were identified. Activated immune cells formed a large proportion of cells in the high infiltration cluster, which correlated to a good prognosis. Differentially expressed genes (DEGs) extracted between two heterogeneous subtypes were used to further explore the underlying immune mechanism and to identify prognostic biomarkers. Functional enrichment analysis revealed that the DEGs were predominately related to some processes involved in activation and regulation of innate immune signaling. Using network analysis, we identified two modules in which genes were selected for further prognostic investigation. Validation by independent datasets revealed that CXCL9 and CXCL13 were good prognostic biomarkers for TNBC. We also performed comparisons between the above two genes and immune markers (CYT, APM, TILs, and TIS), as well as cell checkpoint marker expressions, and found a statistically significant correlation between them in both METABRIC and TCGA datasets. The potential of CXCL9 and CXCL13 to predict chemotherapy sensitivity was also evaluated. We found that the CXCL9 and CXCL13 were good predictors for chemotherapy and their expressions were higher in chemotherapy-responsive patients in contrast to those who were not responsive. In brief, immune infiltrate characterization on TNBC revealed heterogeneous subtypes with unique immune features allowed for the identification of informative and reliable characteristics representative of the local immune tumor microenvironment and were potential candidates to guide the management of TNBC patients.

UBR5 over-expression contributes to poor prognosis and tamoxifen resistance of ERa+ breast cancer by stabilizing β-catenin

BACKGROUND

Tamoxifen (TAM) resistance is a critical clinical challenge in the treatment of ERa+ breast cancer. However, the underlying mechanisms involved in TAM-resistance are not fully understood. Here we study the efficacy of UBR5 in predicting TAM-resistance in ERa+ breast cancer.

METHODS

Western blot RT-PCR and IHC staining were used to evaluate UBR5 protein and mRNA levels in ERa+ breast cancer cell and tissues. MTT assays and colony formation assays were used to measure cell proliferation. The xeno-graft tumor model was used for in vivo study. We performed protein stability assay and ubiquitin assay to detect β-catenin protein degradation. Immuno-precipitation assay was used to detect the interaction between UBR5 and β-catenin. The ubiquitin-based immuno-precipitation based assay was used to detect the ubiquitination of β-catenin.

RESULTS

High UBR5 expression was correlated with poor prognosis in ER+ breast cancer. Importantly, UBR5 expression was remarkably upregulated in TAM-refractory breast cancer tissues compared with their primary paired TAM-untreated tissues. Additionally, UBR5 overexpression caused tamoxifen-resistance in vitro, whereas UBR5 knockdown increased TAM sensitivity. Mechanistic investigations revealed that UBR5 overexpression, through its ubiquitin ligase catalyzing activity, led to up-regulation of β-catenin expression and activity. Finally, our results confirmed that TAM-resistance promoting effects by UBR5 in ERa+ breast cancer cells was at least partly due to β-catenin stabilization, and inhibition of the UBR5/β-catenin signaling re-sensitizing the resistant breast cancer cells to tamoxifen in vivo.

CONCLUSIONS

These findings suggested that UBR5/β-catenin signaling might be a potential therapeutic target for TAM-resistant ERa+ breast cancer.

Metformin suppresses proliferation and invasion of drug-resistant breast cancer cells by activation of the Hippo pathway

Drug resistance limits the clinical efficacy of breast cancer therapies, and overexpression or activation of Yes-associated protein (YAP) is common in drug-resistant cancer cells. Thus, inhibition of YAP may reduce resistance to anti-cancer drugs. Metformin (MET), a first-line diabetes medication that also has anti-tumour activities, induces AMP-activated protein kinase (AMPK), directly phosphorylates YAP and inhibits YAP transcriptional activity. In this study, we determined the effect of MET on the proliferation and invasion of drug-resistant breast cancer cells and then investigated the underlying molecular mechanism. Our in vivo and in vitro experiments indicated that MET suppressed breast cancer by an AMPK-independent pathway to decrease YAP nuclear localization. In drug-sensitive cells, MET activated the Hippo pathway by increasing KIBRA and FRMD6 expression, but this did not occur in drug-resistant cells. Scribble (SCRIB), a cell polarity protein, was notably down-regulated in tamoxifen- and paclitaxel-resistant breast cancer cells relative to sensitive cells. We also found that MET suppressed the proliferation and invasion of drug-resistant breast cancer cells by increasing the expression and cell membrane localization of SCRIB, which enhanced the interaction of SCRIB with MST1 and LATS1, and inhibited YAP nuclear localization and transcriptional activity.

Crumbs protein homolog 3 (CRB3) expression is associated with oestrogen and progesterone receptor positivity in breast cancer

The crumbs protein homolog 3 (CRB3) regulates the tight junction to help maintain epithelial polarity. Altered CRB3 expression was associated with carcinogenesis of epithelial cells. This study detected CRB3 expression in 192 cases of breast cancer tissues and in the Molecular Taxonomy of Breast Cancer International Consortium (Metabric) and The Cancer Genome Atlas (TCGA) datasets for association with triple negative breast cancer (TNBC) phenotypes. The in vitro experiments confirm the ex vivo data. The data showed that levels of both CRB3 mRNA and protein were associated with TNBC phenotypes, ie, 41.1% (39/95) of ER+ breast cancer was CRB3-positive, whereas 26.9% (25/93) ER- tumour was CRB3-positive (P = 0.046). Moreover, 47.6% (30/63) of PR+ breast cancer was CRB3-positive vs 28.4% (33/116) PR- tumours positive for CRB3 (P = 0.013). In addition, 40.1% (27/66) of ER+/PR+ tumour was CRB3-positive, but only 22.4% (19/85) of TNBC showed CRB3 expression (P = 0.048). Indeed, levels of CRB3 mRNA were higher in non-TNBC than TNBC in both Metabric (P = 3.682e-10) and TCGA datasets (P = 2.501e-07). The in vitro data showed that CRB3 expression was higher in luminal (MCF7 and T47D) than in HER2 (MDA-MB-453 and SK-BR-3) and basal (MDA-MB-231 and BT-549) breast cancer cell lines. More interestingly, ERα regulated expression of CRB3 protein in MCF7 and BT-549 cells and ERα expression was associated with CRB3 expression in breast cancer tissues specimens. This study demonstrated that ERα could be a novel regulator for CRB3 expression in breast cancer.

Long noncoding RNA LINC00511 contributes to breast cancer tumourigenesis and stemness by inducing the miR-185-3p/E2F1/Nanog axis

BACKGROUND

Emerging evidence have illustrated the vital role of long noncoding RNAs (lncRNAs) long intergenic non-protein coding RNA 00511 (LINC00511) on the human cancer progression and tumorigenesis. However, the role of LINC00511 in breast cancer tumourigenesis is still unknown. This research puts emphasis on the function of LINC00511 on the breast cancer tumourigenesis and stemness, and investigates the in-depth mechanism.

METHODS

The lncRNA and RNA expression were measured using RT-PCR. Protein levels were measured using western blotting analysis. CCK-8, colony formation assays and transwell assay were performed to evaluate the cell proliferation ability and invasion. Sphere-formation assay was also performed for the stemness. Bioinformatic analysis, chromatin immunoprecipitation (ChIP) and luciferase reporter assays were carried to confirm the molecular binding.

RESULTS

LINC00511 was measured to be highly expressed in the breast cancer specimens and the high-expression was correlated with the poor prognosis. Functionally, the gain and loss-of-functional experiments revealed that LINC00511 promoted the proliferation, sphere-formation ability, stem factors (Oct4, Nanog, SOX2) expression and tumor growth in breast cancer cells. Mechanically, LINC00511 functioned as competing endogenous RNA (ceRNA) for miR-185-3p to positively recover E2F1 protein. Furthermore, transcription factor E2F1 bind with the promoter region of Nanog gene to promote it transcription.

CONCLUSION

In conclusion, our data concludes that LINC00511/miR-185-3p/E2F1/Nanog axis facilitates the breast cancer stemness and tumorigenesis, providing a vital insight for them.

DLG5 suppresses breast cancer stem cell-like characteristics to restore tamoxifen sensitivity by inhibiting TAZ expression

Tamoxifen (TAM) is a primary drug for treatment of estrogen receptor positive breast cancer. However, TAM resistance remains a serious threat to breast cancer patients and may be attributed to increased stemness of breast cancer. Here, we show that discs large homolog 5 (DLG5) expression is down‐regulated in TAM‐resistant breast cancer and cells. DLG5 silencing decreased the sensitivity to TAM and increased the frequency and stemness of CD44⁺/CD24⁻ breast cancer stem cells (BCSCs) and TAZ, a transducer of the Hippo pathway, expression in MCF7 cells while DLG5 overexpression had opposite effects. TAZ silencing restored the sensitivity to TAM and reduced the frequency and stemness in TAM‐resistant breast cancer cells. Taken together, our data indicate that down‐regulated DLG5 expression increases the stemness of breast cancer cells by enhancing TAZ expression, contributing to TAM resistance in breast cancer.

CRB3 and the FERM protein EPB41L4B regulate proliferation of mammary epithelial cells through the release of amphiregulin

Numerous observations have suggested a connection between the maintenance of cell polarity and control of cell proliferation; however, the mechanisms underlying these connections remain poorly understood. Here we found that ectopic expression of CRB3, which was previously shown to restore tight junctions and membrane polarity in MCF-10A cells, induced a hyperproliferative phenotype, with significantly enlarged acini in basement membrane culture, similar to structures induced by expression of proliferative oncogenes such as cyclinD1. We found that CRB3-induced proliferation is epidermal growth factor (EGF)-independent and occurs through a mechanism that involves secretion of the EGF-family ligand, amphiregulin (AREG). The increase in AREG secretion is associated with an increase in the number and size of both early and late endosomes. Both the proliferative and endocytic phenotypes associated with CRB3 expression require the FERM-binding domain (FBD) but not the PDZ-binding domain of CRB3, arguing that this proliferative phenotype is independent of the PDZ-dependent polarity signaling by CRB3. We identified the FBD-containing protein, EPB41L4B, as an essential mediator of CRB3-driven proliferation and observed that the CRB3-dependent changes in endocytic trafficking were also dependent on EPB41L4B. Taken together, these data reveal a previously uncharacterized role for CRB3 in regulating proliferation in mammalian cells that is associated with changes in the endocytic trafficking machinery.

The clinicopathological significance of ZNF10 in invasive ductal carcinoma of the breast

The aim of this study was to clarify the clinicopathological features and role of zinc finger protein 10 (ZNF10) in breast invasive ductal cancer (IDC). Our data first showed that ZNF10 expression was higher in 8 pairs of fresh breast IDC and breast cancer cell lines compared with their respective adjacent non-tumor breast tissues. ZNF10 expression was significantly higher in IDC compared with DCIS and fibroadenoma of the breast. ZNF10 expression was significantly associated with patients' age, tumor stage, and breast cancer molecular subtype. ZNF10 knockdown inhibited breast cancer cell proliferation, colony formation, cell cycle progression, cell migration, and invasion but induced apoptosis. ZNF10 knockdown also suppressed the tumorigenicity of breast cancer in vivo. The underlying mechanism study showed that ZNF10 regulated the β-catenin signaling pathway in breast cancer. ZNF10 might bind to the region (nucleotides -300 to +100) of the β-catenin promoter. In conclusion, our results first suggest that ZNF10 promotes the carcinogenesis and progression of breast IDC via the β-catenin signaling pathway. Targeting ZNF10 might be a novel treatment strategy for breast cancer.

Elevated CRB3 expression suppresses breast cancer stemness by inhibiting β-catenin signalling to restore tamoxifen sensitivity

Tamoxifen is a first‐line drug for hormone therapy (HT) in oestrogen receptor‐positive breast cancer patients. However, 20% to 30% of those patients are resistant to tamoxifen treatment. Cancer stem cells (CSCs) have been implicated as one of the mechanisms responsible for tamoxifen resistance. Our previous study indicated that decreased expression of the CRB3 gene confers stem cell characteristics to breast cancer cells. In the current investigation, we found that most of the breast cancer patient tissues resistant to tamoxifen were negative for CRB3 protein and positive for β‐catenin protein, in contrast to their matched primary tumours by immunohistochemical analysis. Furthermore, expression of CRB3 mRNA and protein was low, while expression of β‐catenin mRNA and protein was high in tamoxifen resistance cells (LCC2 and T47D TamR) contrast to their corresponding cell lines MCF7 and T47D. Similarly, CRB3 overexpression markedly restored the tamoxifen sensitivity of TamR cells by the MTT viability assay. Finally, we found that CRB3 suppressed the stemness of TamR cells by inhibiting β‐catenin signalling, which may in turn lead to a decrease in the breast cancer cell population. Furthermore, these findings indicate that CRB3 is an important regulator for breast cancer stemness, which is associated with tamoxifen resistance.