Cytoplasmic localization of beta-catenin is a marker of poor outcome in breast cancer patients

BMP Stimulation Differentially Affects Phosphorylation and Protein Stability of β-Catenin in Breast Cancer Cell Lines

Increased expression and nuclear translocation of β-CATENIN is frequently observed in breast cancer, and it correlates with poor prognosis. Current treatment strategies targeting β-CATENIN are not as efficient as desired. Therefore, detailed understanding of β-CATENIN regulation is crucial. Bone morphogenetic proteins (BMP) and Wingless/Integrated (WNT) pathway crosstalk is well-studied for many cancer types including colorectal cancer, whereas it is still poorly understood for breast cancer. Analysis of breast cancer patient data revealed that BMP2 and BMP6 were significantly downregulated in tumors. Since mutation frequency in genes enhancing β-CATENIN protein stability is relatively low in breast cancer, we aimed to investigate whether decreased BMP ligand expression could contribute to a high protein level of β-CATENIN in breast cancer cells. We demonstrated that downstream of BMP stimulation, SMAD4 is required to reduce β-CATENIN protein stability through the phosphorylation in MCF7 and T47D cells. Consequently, BMP stimulation reduces β-CATENIN levels and prevents its nuclear translocation and target gene expression in MCF7 cells. Conversely, BMP stimulation has no effect on β-CATENIN phosphorylation or stability in MDA-MB-231 and MDA-MB-468 cells. Likewise, SMAD4 modulation does not alter the response of those cells, indicating that SMAD4 alone is insufficient for BMP-induced β-CATENIN phosphorylation. While our data suggest that considering BMP activity may serve as a prognostic marker for understanding β-CATENIN accumulation risk, further investigation is needed to elucidate the differential responsiveness of breast cancer cell lines.

Effect of aza-BODIPY-photodynamic therapy on the expression of carcinoma-associated genes and cell death mode

BACKGROUND

Breast cancer is the most common cancer affecting women worldwide.Photodynamic therapy(PDT) has now proven to be a promising form of cancer therapy due to its targeted and low cytotoxicity to healthy cells and tissues.PDT is a technique used to create cell death localized by light after application of a light-sensitive agent.Aza-BODIPY is a promising photosensitizer for use in PDT. Our results showed that aza-BODIPY-PDT induced apoptosis, probably through p53 and caspase3 in MCF-7 cells. Future studies should delineate the molecular mechanisms underlying aza-BODIPY-PDT-induced cell death for a better understanding of the signaling pathways modulated by the therapy so that this novel technology could be implemented in the clinic for treating breast cancer.

AIM

In this study,we aimed to determine the change in the expression levels of 88 carcinoma-associated genes induced by aza-BODIPY-PDT were analyzed so as to understand the specific pathways that are modulated by aza-BODIPY-PDT.

MATERIAL METHOD

In this study,the molecular basis of the anti-cancer activity of aza-BODIPY-PDT was investigated.Induction of apoptosis and necrosis in MCF-7 breast cancer cells after treatment with aza- BODIPY derivative with phthalonitrile substituents (aza-BODIPY) followed by light exposure was evaluated by Annexin V 7- Aminoactinomycin D (7-AAD) flow cytometry.

RESULTS

Aza-BODIPY-PDT induced cell death in MCF-7 cells treated with aza-BODIPY-PDT; flow cytometry revealed that 28 % of the cells died by apoptosis. Seven of the 88 carcinoma-associated genes that were assayed were differentially expressed -EGF, LEF1, WNT1, TCF7, and TGFBR2 were downregulated, and CASP3 and TP53 were upregulated - in cells subjected to aza-BODIPY-PDT.This made us think that the aza-BODIPY-PDT induced caspase 3 and p53-mediated apoptosis in MCF7 cells.

CONCLUSION

In our study,it was determined that the application of aza-BODIPY-PDT to MCF7 cells had a negative effect on cell connectivity and cell cycle.The fact that the same effect was not observed in control cells and MCF7 cells in the dark field of aza-BODIPY indicates that aza-BODIPY has a strong phodynamic anticancer effect.

Alginate-Chitosan Hydrogels Containing shRNA Plasmid for Inhibition of CTNNB1 Expression in Breast Cancer Cells

The hydrogels prepared with alginate and chitosan polymers were prepared to deliver the shRNA-encoding plasmid (pshRNA) to MDA-MB-231 cells for the inhibition of β-catenin (CTNNB1), which was reported to be overexpressed in breast cancer. Polyion complex hydrogels prepared using sodium alginate and chitosan were characterized by Fourier transform infrared spectrometry (FTIR) analysis, scanning electron microscope (SEM) analysis, swelling, and degradation properties. After the release properties and serum stability of pshRNA-loaded hydrogels were determined, their cytotoxicity, transfection efficacy, and effects on CTNNB1 expression were investigated in MDA-MB-231 cells. All hydrogels were shown to protect pshRNA from the enzymatic activity of serum and to deliver pshRNA to cells efficiently. As a result of transfection studies, pshRNA-loaded hydrogels reduced CTNNB1 expression by up to 30.25%. Cell viability also decreased by 38% in cells treated with 2.5% (w/v) alginate-chitosan hydrogel containing pshRNA targeting CTNNB1. Alginate-chitosan hydrogels were shown to be a suitable matrix system for local gene delivery.

Tumor-expressed factor VII is associated with survival and regulates tumor progression in breast cancer

Cancer enhances the risk of venous thromboembolism, but a hypercoagulant microenvironment also promotes cancer progression. Although anticoagulants have been suggested as a potential anticancer treatment, clinical studies on the effect of such modalities on cancer progression have not yet been successful for unknown reasons. In normal physiology, complex formation between the subendothelial-expressed tissue factor (TF) and the blood-borne liver-derived factor VII (FVII) results in induction of the extrinsic coagulation cascade and intracellular signaling via protease-activated receptors (PARs). In cancer, TF is overexpressed and linked to poor prognosis. Here, we report that increased levels of FVII are also observed in breast cancer specimens and are associated with tumor progression and metastasis to the liver. In breast cancer cell lines, tumor-expressed FVII drives changes reminiscent of epithelial-to-mesenchymal transition (EMT), tumor cell invasion, and expression of the prometastatic genes, SNAI2 and SOX9. In vivo, tumor-expressed FVII enhanced tumor growth and liver metastasis. Surprisingly, liver-derived FVII appeared to inhibit metastasis. Finally, tumor-expressed FVII-induced prometastatic gene expression independent of TF but required a functional endothelial protein C receptor, whereas recombinant activated FVII acting via the canonical TF:PAR2 pathway inhibited prometastatic gene expression. Here, we propose that tumor-expressed FVII and liver-derived FVII have opposing effects on EMT and metastasis.

Cytosolic EpCAM cooperates with H-Ras to regulate epithelial to mesenchymal transition through ZEB1

Next generation sequencing of human cancer mutations has identified novel therapeutic targets. Activating Ras oncogene mutations play a central role in oncogenesis, and Ras-driven tumorigenesis upregulates an array of genes and signaling cascades that can transform normal cells into tumor cells. In this study, we investigated the role of altered localization of epithelial cell adhesion molecule (EpCAM) in Ras-expressing cells. Analysis of microarray data demonstrated that Ras expression induced EpCAM expression in normal breast epithelial cells. Fluorescent and confocal microscopy showed that H-Ras mediated transformation also promoted epithelial-to-mesenchymal transition (EMT) together with EpCAM. To consistently localize EpCAM in the cytosol, we generated a cancer-associated EpCAM mutant (EpCAM-L240A) that is retained in the cytosol compartment. Normal MCF-10A cells were transduced with H-Ras together with EpCAM wild-type (WT) or EpCAM-L240A. WT-EpCAM marginally effected invasion, proliferation, and soft agar growth. EpCAM-L240A, however, markedly altered cells and transformed to mesenchymal phenotype. Ras-EpCAM-L240A expression also promoted expression of EMT factors FRA1, ZEB1 with inflammatory cytokines IL-6, IL-8, and IL1. This altered morphology was reversed using MEK-specific inhibitors and to some extent JNK inhibition. Furthermore, these transformed cells were sensitized to apoptosis using paclitaxel and quercetin, but not other therapies. For the first time, we have demonstrated that EpCAM mutations can cooperate with H-Ras and promote EMT. Collectively, our results highlight future therapeutic opportunities in EpCAM and Ras mutated cancers.

Detection of Increased Expression of Claudin-1 in Triple-Negative Breast Cancer: Analysis and Clinical-Pathological Correlation

Background Triple-negative breast cancer (TNBC) is a highly aggressive disease that lacks therapeutic targets and prognostic biomarkers. Claudin-1 is a well-described tight junction protein with prognostic value in many human cancers. Aims The need for the discovery of biomarkers of TNBC disease was a major reason for this study. Claudin-1 is a tight junction protein that has shown promising results in the prognosis and management of cancer in general. In the breast, claudin-1 expression and significance have shown variable results, especially in TNBC patients. Our study assessed expression of claudin-1 in a group of TNBC patients, and correlated this expression with clinical-pathological parameters, and with the expression of β-catenin. Materials and methods Tissues from a group of 52 TNBC patients were retrieved from the archives of the community hospital. All related information including demographical, pathologic and clinical data were retrieved. Immunohistochemistry assays of a rabbit polyclonal antibody anti-human claudin-1 were applied using the avidin-biotin peroxidase methodology. Results A statistically significant majority of TNBC cases positively expressed claudin-1 (81%, χ2=13.705; p<0.001). Most TNBC cases had grade 2 β-catenin expression (77.5%; p<0.001), and positive expression for claudin-1 correlated with that of β-catenin (χ2= 23.757; p<0.001). Claudin-1 and β-catenin expressions within tumour cells shared several features including absent or weakness of membranous expression, and redistribution of both proteins to the cytoplasm of tumour cells, and in some cases to the nuclei of these cells. Claudin-1 expression also correlates with adverse survival outcomes, where only four of 20 claudin-1-positive patients who received neo-adjuvant chemotherapy (NAC) achieved pathological complete response (pCR). Conclusions The above presents a complex role of claudin-1 in TNBC patients. In this study, claudin-1 expression was associated with poor prognostic features including invasion, metastases and adverse clinical outcomes. Claudin-1 expression in TNBC correlated with the expression of β-catenin, an important oncogene and a major contributor to the epithelial mesenchymal transition (EMT) phenomenon. Overall, the above results may serve as an impetus for further mechanistic studies to assess the exact role of claudin-1 in TNBC and its possible use in the management of this subset of breast cancer.

WNT3a Signaling Inhibits Aromatase Expression in Breast Adipose Fibroblasts-A Possible Mechanism Supporting the Loss of Estrogen Responsiveness of Triple-Negative Breast Cancers

Estrogen-dependent breast cancers rely on a constant supply of estrogens and expression of estrogen receptors. Local biosynthesis, by aromatase in breast adipose fibroblasts (BAFs), is their most important source for estrogens. Triple-negative breast cancers (TNBC) rely on other growth-promoting signals, including those from the Wnt pathway. In this study, we explored the hypothesis that Wnt signaling alters the proliferation of BAFs, and is involved in regulation of aromatase expression in BAFs. Conditioned medium (CM) from TNBC cells and WNT3a consistently increased BAF growth, and reduced aromatase activity up to 90%, by suppression of the aromatase promoter I.3/II region. Database searches identified three putative Wnt-responsive elements (WREs) in the aromatase promoter I.3/II. In luciferase reporter gene assays, promoter I.3/II activity was inhibited by overexpression of full-length T-cell factor (TCF)-4 in 3T3-L1 preadipocytes, which served as a model for BAFs. Full-length lymphoid enhancer-binding factor (LEF)-1 increased the transcriptional activity. However, TCF-4 binding to WRE1 in the aromatase promoter, was lost after WNT3a stimulation in immunoprecipitation-based in vitro DNA-binding assays, and in chromatin immunoprecipitation (ChIP). In vitro DNA-binding assays, ChIP, and Western blotting revealed a WNT3a-dependent switch of nuclear LEF-1 isoforms towards a truncated variant, whereas β-catenin levels remained unchanged. This LEF-1 variant revealed dominant negative properties, and most likely recruited enzymes involved in heterochromatin formation. In addition, WNT3a induced the replacement of TCF-4 by the truncated LEF-1 variant, on WRE1 of the aromatase promoter I.3/II. The mechanism described here may be responsible for the loss of aromatase expression predominantly associated with TNBC. Tumors with (strong) expression of Wnt ligands actively suppress aromatase expression in BAFs. Consequently a reduced estrogen supply could favor the growth of estrogen-independent tumor cells, which consequently would make estrogen receptors dispensable. In summary, canonical Wnt signaling within (cancerous) breast tissue may be a major factor controlling local estrogen synthesis and action.

Gallic acid mediates tumor-suppressive effects on osteosarcoma through the H19-Wnt/β-catenin regulatory axis

Background

Osteosarcoma (OS) is the most common primary malignancy in bone tissues, and effective therapeutics remain absent in clinical practice. Traditional Chinese medicines (TCM) have been used for thousands of years, which provide great insights into OS management. Gallic acid (GA) is a natural phenolic acid enriched in various foods and herbs. Several pharmacological activities of GA such as anti-oxidation and anti-inflammation have been well-established. However, its biological function in OS remains not fully understood.

Methods

The potential anti-cancer properties of GA were evaluated in 143 ​B, U2OS and MG63 ​cells. Its effects on cell growth, cell cycle, apoptosis and migration were examined in these OS cells. The lncRNA H19 and Wnt/β-catenin signaling were detected by qPCR, luciferase activity and Western blotting assays. The in vivo effect of GA on tumor growth was investigated using an orthotopic mouse model.

Results

In the present study, GA was found to suppress the tumor growth in vitro via inducing cell cycle arrest and apoptosis in OS cells, and inhibit the invasion and metastasis as well. Using the orthotopic animal model, GA was also found to suppress tumorigenesis in vivo. Long noncoding RNA (lncRNA) H19 was demonstrated to be down-regulated by GA, and thus disrupted the canonical Wnt/β-catenin signaling in OS cells. Furthermore, the ectopic expression of H19 rescued the GA-induced suppressive effects on tumor growth and metastasis, and partially reversed the inactivation of Wnt/β-catenin signaling.

Conclusions

Taken together, our results indicated that GA inhibited tumor growth through an H19-mediated Wnt/β-catenin signaling regulatory axis in OS cells.

The translational potential of this article

The information gained from this study provides a novel underlying mechanism of GA mediated anti-OS activity, suggesting that GA may be a promising drug candidate for OS patients.

PLA2G7/PAF-AH as Potential Negative Regulator of the Wnt Signaling Pathway Mediates Protective Effects in BRCA1 Mutant Breast Cancer

Past studies have confirmed that aberrant activation of the Wnt/β-catenin signaling is associated with tumorigenesis and metastasis in breast cancer, while the role of platelet-activating factor acetylhydrolase (PLA2G7/PAF-AH) in this signaling pathway remains unclear. In this study, we analyze the functional impact of PAF-AH on BRCA1 mutant breast cancer and explore its relationship to the Wnt signaling pathway. By performing immunohistochemistry, PAF-AH expression and β-catenin expression were examined in both BRCA1 WT and BRCA1 mutant breast cancer specimens. The BRCA1 mutant breast cancer cell line HCC1937 was used for in vitro experiments to assess the impact of PAF-AH on cellular functions. The intracellular distribution of β-catenin depending on PLA2G7/PAF-AH expression was investigated by immunocytochemistry. Significantly higher nuclear expression levels of PAF-AH were found in BRCA1 mutant tissue specimens than in BRCA1 WT samples. Cell viability, proliferation, and the motility rate of HCC1937 were significantly enhanced after PLA2G7 silencing, which indicated a protective role of PAF-AH in breast cancer. Nuclear PAF-AH expressed correlatedly with membranous β-catenin. PLA2G7 silencing provoked the β-catenin translocation from the membrane to the nucleus and activated Wnt signaling downstream genes. Our data showed a protective effect of high PAF-AH expression in BRCA1 mutant breast cancer. PAF-AH may achieve its protective effect by negatively regulating the Wnt pathway. In conclusion, our research sheds new light on the regulatory pathways in BRCA1 mutant breast cancer.

LRP6 Receptor Plays Essential Functions in Development and Human Diseases

LRP6 is a member of the low-density lipoprotein receptor superfamily of cell-surface receptors. It is required for the activation of the Wnt/β-catenin signalling pathway. LRP6 is detected in different tissue types and is involved in numerous biological activities such as cell proliferation, specification, metastatic cancer, and embryonic development. LRP6 is essential for the proper development of different organs in vertebrates, such as Xenopus laevis, chickens, and mice. In human, LRP6 overexpression and mutations have been reported in multiple complex diseases including hypertension, atherosclerosis, and cancers. Clinical studies have shown that LRP6 is involved in various kinds of cancer, such as bladder and breast cancer. Therefore, in this review, we focus on the structure of LRP6 and its interactions with Wnt inhibitors (DKK1, SOST). We also discuss the expression of LRP6 in different model systems, with emphasis on its function in development and human diseases.

β-catenin plus PROX1 immunostaining stratifies disease progression and patient survival in neoadjuvant-treated pancreatic cancer

BACKGROUND

Wnt/β-catenin signaling is a highly conserved signaling pathway that regulates the transcription factor PROX1. The role of β-catenin and PROX1 in pancreatic cancer is ambiguous, as some studies have associated their expression with tumor regression and some with tumor progression.

OBJECTIVE

We have investigated their expression in surgically treated pancreatic cancer patients receiving neoadjuvant therapy (NAT), and patients treated upfront with surgery (US). We furthermore compared the expression of β-catenin and PROX1 between patients who had a good or poor response to NAT.

METHODS

We evaluated β-catenin and PROX1 expression through immunohistochemistry in 88 neoadjuvant and 144 upfront surgery patients by scoring the intensity of the immunopositivity as 0-3, corresponding to negative, weak, moderate, or strong. We developed a six-tier grading scheme for the neoadjuvant responses by analyzing the remaining tumor cells in surgical specimen histological sections.

RESULTS

Strong β-catenin immunopositivity associated with improved survival in the patients with good NAT-response (≤10% residual tumor cells) (Hazard ratio [HR] 0.26 95%, confidence interval [CI] 0.07-0.88 p = 0.030). Additionally, the combined moderate β-catenin and PROX1 expression associated with improved survival (HR 0.20 95% CI 0.05-0-76 p = 0.018) among the good responders. Among the patients with a poor NAT-response (> 10% residual tumor cells), both strong β-catenin immunopositivity and strong combined β-catenin and PROX1 associated with shorter survival (HR 2.03 95% CI 1.16-3.55 p = 0.013, and HR 3.1 95% CI 1.08-8.94 p = 0.03, respectively). PROX1 alone was not associated with survival.

CONCLUSIONS

Strong β-catenin immunopositivity and combined strong or moderate β-catenin and PROX1 immunopositivity associated with improved survival among the good NAT-responders and worse survival among the poor NAT-responders.

The role of R-spondin proteins in cancer biology

R-spondin (RSPO) proteins constitute a family of four secreted glycoproteins (RSPO1-4) that have appeared as multipotent signaling ligands. The best-known molecular function of RSPOs lie within their capacity to agonize the Wnt/β-catenin signaling pathway. As RSPOs act upon cognate receptors LGR4/5/6 that are typically expressed by stem cells and progenitor cells, RSPO proteins importantly potentiate Wnt/β-catenin signaling especially within these proliferative stem cell compartments. Since multiple organs express LGR4/5/6 receptors and RSPO ligands within their stem cell niches, RSPOs can exert an influential role in stem cell regulation throughout the body. Inherently, over the last decade a multitude of reports implicated the deregulation of RSPOs in cancer development. First, RSPO2 and RSPO3 gene fusions with concomitant enhanced expression have been identified in colon cancer patients, and proposed as an alternative driver of Wnt/β-catenin hyperactivation that earmarks cancer in the colorectal tract. Moreover, the causal oncogenic capacity of RSPO3 overactivation has been demonstrated in the mouse intestine. As a paradigm organ in this field, most of current knowledge about RSPOs in cancer is derived from studies in the intestinal tract. However, RSPO gene fusions as well as enhanced RSPO expression have been reported in multiple additional cancer types, affecting different organs that involve divergent stem cell hierarchies. Importantly, the emerging oncogenic role of RSPO and its potential clinical utility as a therapeutic target have been recognized and investigated in preclinical and clinical settings. This review provides a survey of current knowledge on the role of RSPOs in cancer biology, addressing the different organs implicated, and of efforts made to explore intervention opportunities in cancer cases with RSPO overrepresentation, including the potential utilization of RSPO as novel therapeutic target itself.

mRNA coexpression patterns of Wnt pathway components and their clinicopathological associations in breast and colorectal cancer

Aberrant Wnt signaling is implicated in carcinogenesis triggering efforts for the development of new therapeutic agents, many of which have entered clinical trials. We extend our previous analysis of WNT3, FZD7, LEF1 expression levels in breast and colorectal cancer including WNT2, FZD4 and β-catenin expression, in an effort to delineate their relative expression levels along with concurrent expression patterns and possible prognostic value. We analyzed 82 breast and 102 colorectal carcinomas for relative mRNA expression levels of the investigated genes by RT-PCR relative quantification with the ΔΔCt method. Statistical analysis was performed in order to determine associations of relative mRNA expression and linear correlations. β-catenin expression was determined by immunochemistry. Regarding breast carcinomas, decreased relative mRNA expression levels of WNT2, FZD4 were found frequently and WNT2 expression was correlated with ER/ PR status (p = 0.045/p = 0.028), whereas β-catenin with grade (p = 0.026). In colorectal carcinomas, increased relative mRNA expression levels of WNT2 and FZD4 were found in 59% and 32% of cases respectively, whereas β-catenin showed decreased mRNA expression levels in 57% of cases and a correlation with pN-category (p = 0.037). Linear correlations were observed between WNT2/FZD4 (R=0.542, p < 0.001), WNT2/β-catenin (R=0.254, p = 0.010), FZD4/β-catenin (R=0.406, p < 0.001) expression and a correlation between mRNA expression and membranous/cytoplasmic β-catenin emerged (p = 0.039/0.046). Our results suggest a possible clinical significance for Wnt pathway gene expression levels in both tumour types. The concurrent expression of the investigated genes as well as the different expression profiles, underlines the complexity of this pathway and the necessity of patient selection in order to maximize the efficacy of drugs targeting Wnt pathway.

Metastatic Breast Cancer, Organotropism and Therapeutics: A Review

The final stage of breast cancer involves spreading breast cancer cells to the vital organs like the brain, liver lungs and bones in the process called metastasis. Once the target organ is overtaken by the metastatic breast cancer cells, its usual function is compromised causing organ dysfunction and death. Despite the significant research on breast cancer metastasis, it's still the main culprit of breast cancer-related deaths. Exploring the complex molecular pathways associated with the initiation and progression of breast cancer metastasis could lead to the discovery of more effective ways of treating the devastating phenomenon. The present review article highlights the recent advances to understand the complexity associated with breast cancer metastases, organotropism and therapeutic advances.

Nucleolin Targeting by N6L Inhibits Wnt/β-Catenin Pathway Activation in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive and resistant cancer with no available effective therapy. We have previously demonstrated that nucleolin targeting by N6L impairs tumor growth and normalizes tumor vessels in PDAC mouse models. Here, we investigated new pathways that are regulated by nucleolin in PDAC. We found that N6L and nucleolin interact with β-catenin. We found that the Wnt/β-catenin pathway is activated in PDAC and is necessary for tumor-derived 3D growth. N6L and nucleolin loss of function induced by siRNA inhibited Wnt pathway activation by preventing β-catenin stabilization in PDAC cells. N6L also inhibited the growth and the activation of the Wnt/β-catenin pathway in vivo in mice and in 3D cultures derived from MIA PaCa2 tumors. On the other hand, nucleolin overexpression increased β-catenin stabilization. In conclusion, in this study, we identified β-catenin as a new nucleolin interactor and suggest that the Wnt/β-catenin pathway could be a new target of the nucleolin antagonist N6L in PDAC.

Optimization of the clofazimine structure leads to a highly water-soluble C3-aminopyridinyl riminophenazine endowed with improved anti-Wnt and anti-cancer activity in vitro and in vivo

Triple-negative breast cancer (TNBC) is a cancer subtype critically dependent upon excessive activation of Wnt pathway. The anti-mycobacterial drug clofazimine is an efficient inhibitor of canonical Wnt signaling in TNBC, reducing tumor cell proliferation in vitro and in animal models. These properties make clofazimine a candidate to become first targeted therapy against TNBC. In this work, we optimized the clofazimine structure to enhance its water solubility and potency as a Wnt inhibitor. After extensive structure-activity relationships investigations, the riminophenazine 5-(4-(chlorophenyl)-3-((2-(piperazin-1-yl)ethyl)imino)-N-(pyridin-3-yl)-3,5-dihydrophenazin-2-amine (MU17) was identified as the new lead compound for the riminophenazine-based targeted therapy against TNBC and Wnt-dependent cancers. Compared to clofazimine, the water-soluble MU17 displayed a 7-fold improved potency against Wnt signaling in TNBC cells resulting in on-target suppression of tumor growth in a patient-derived mouse model of TNBC. Moreover, allowing the administration of reduced yet effective dosages, MU17 displayed no adverse effects, most notably no clofazimine-related skin coloration.

MAPS: machine-assisted phenotype scoring enables rapid functional assessment of genetic variants by high-content microscopy

BACKGROUND

Genetic testing is widely used in evaluating a patient's predisposition to hereditary diseases. In the case of cancer, when a functionally impactful mutation (i.e. genetic variant) is identified in a disease-relevant gene, the patient is at elevated risk of developing a lesion in their lifetime. Unfortunately, as the rate and coverage of genetic testing has accelerated, our ability to assess the functional status of new variants has fallen behind. Therefore, there is an urgent need for more practical, streamlined and cost-effective methods for classifying variants.

RESULTS

To directly address this issue, we designed a new approach that uses alterations in protein subcellular localization as a key indicator of loss of function. Thus, new variants can be rapidly functionalized using high-content microscopy (HCM). To facilitate the analysis of the large amounts of imaging data, we developed a new software toolkit, named MAPS for machine-assisted phenotype scoring, that utilizes deep learning to extract and classify cell-level features. MAPS helps users leverage cloud-based deep learning services that are easy to train and deploy to fit their specific experimental conditions. Model training is code-free and can be done with limited training images. Thus, MAPS allows cell biologists to easily incorporate deep learning into their image analysis pipeline. We demonstrated an effective variant functionalization workflow that integrates HCM and MAPS to assess missense variants of PTEN, a tumor suppressor that is frequently mutated in hereditary and somatic cancers.

CONCLUSIONS

This paper presents a new way to rapidly assess variant function using cloud deep learning. Since most tumor suppressors have well-defined subcellular localizations, our approach could be widely applied to functionalize variants of uncertain significance and help improve the utility of genetic testing.

Understanding the Molecular Mechanism of miR-877-3p Could Provide Potential Biomarkers and Therapeutic Targets in Squamous Cell Carcinoma of the Cervix

No therapeutic targets and molecular biomarkers are available in cervical cancer (CC) management. In other cancer types, micro-RNA-877-3p (miR-877-3p) has been associated with events relevant for CC development. Thus, we aimed to determine miR-877-3p role in CC. miR-877-3p levels were examined by quantitative-PCR in 117 cervical lesions and tumors. Effects on CC cell proliferation, migration, and invasion were evaluated upon anti-miR-877-3p transfection. miR-877-3p dependent molecular mechanism was comprehensively explored by proteomics, dual-luciferase reporter assay, western blot, and immunohistochemistry. Cervical tumors expressed higher miR-877-3p levels than benign lesions. miR-877-3p promoted CC cell migration and invasion, at least partly by modulating cytoskeletal protein folding through the chaperonin-containing T-complex protein 1 complex. Notably, miR-877-3p silencing synergized with paclitaxel. Interestingly, miR-877-3p downregulated the levels of an in silico-predicted target, ZNF177, whose expression and subcellular location significantly distinguished high-grade squamous intraepithelial lesions (HSILs) and squamous cell carcinomas of the cervix (SCCCs). Cytoplasmic ZNF177 was significantly associated with worse progression-free survival in SCCC. Our results suggest that: (i) miR-877-3p is a potential therapeutic target whose inhibition improves paclitaxel effects; (ii) the expression and location of its target ZNF177 could be diagnostic biomarkers between HSIL and SCCC; and (iii) cytoplasmic ZNF177 is a poor-prognosis biomarker in SCCC.

Aggressiveness and Metastatic Potential of Breast Cancer Cells Co-Cultured with Preadipocytes and Exposed to an Environmental Pollutant Dioxin: An in Vitro and in Vivo Zebrafish Study

BACKGROUND

Breast cancer (BC) is a major public health concern, and its prognosis is very poor once metastasis occurs. The tumor microenvironment and chemical pollution have been suggested recently to contribute, independently, to the development of metastatic cells. The BC microenvironment consists, in part, of adipocytes and preadipocytes in which persistent organic pollutants (POPs) can be stored.

OBJECTIVES

We aimed to test the hypothesis that these two factors (2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an extensively studied, toxic POP and the microenvironment) may interact to increase tumor aggressiveness.

METHODS

We used a co-culture model using BC MCF-7 cells or MDA-MB-231 cells together with hMADS preadipocytes to investigate the contribution of the microenvironment and 2,3,7,8-tetrachlorodibenzo-p-dioxin TCDD on BC cells. Global differences were characterized using a high-throughput proteomic assay. Subsequently we measured the BC stem cell-like activity, analyzed the cell morphology, and used a zebrafish larvae model to study the metastatic potential of the BC cells.

RESULTS

We found that coexposure to TCDD and preadipocytes modified BC cell properties; moreover, it induced the expression of ALDH1A3, a cancer stem cell marker, and the appearance of giant cancer cells with cell-in-cell structures (CICs), which are associated with malignant metastatic progression, that we demonstrated in vivo.

DISCUSSION

The results of our study using BC cell lines co-cultured with preadipocytes and a POP and an in vivo zebrafish model of metastasis suggest that the interactions between BC cells and their microenvironment could affect their invasive or metastatic potential. https://doi.org/10.1289/EHP7102.

H19-Wnt/β-catenin regulatory axis mediates the suppressive effects of apigenin on tumor growth in hepatocellular carcinoma

Hepatocellular Carcinoma (HCC) is one of the leading causes of cancer-related deaths in the world. However, the effective pharmacological approaches remain scanty in clinical practice. As a bioactive flavonoid, apigenin (API) is enriched in common fruits and vegetables. Although pharmacological activities of API have been widely investigated, its biological function in HCC remains obscure. In the present study, we found that API strongly suppressed cell growth and induced apoptosis in HCC cells. Using a xenograft mice model, API was demonstrated to inhibit the in vivo tumor growth. It is known that the long non-coding RNA H19, which is frequently elevated in HCC, plays a vital role in mediating tumorigenesis and cancer progression. Our results demonstrated that H19 was down-regulated by API, and thereby induced the inactivation of the canonical Wnt/β-catenin signaling. In conclusion, our results demonstrated that API was able to suppress tumor growth of HCC through H19-mediated Wnt/β-catenin signaling regulatory axis, suggesting that API may be a promising candidate for developing novel therapeutic approaches against liver cancer.

Transcriptional co-activators YAP/TAZ: Potential therapeutic targets for metastatic breast cancer

Breast cancer is the most commonly diagnosed cancer among women. Although routine and targeted therapies have improved the survival rate, there are still considerable challenges in the treatment of breast cancer. Metastasis is the leading cause of death in patients diagnosed with breast cancer. Yes-associated protein (YAP) and/or PDZ binding motif (TAZ) are usually abnormally activated in breast cancer leading to a variety of effects on tumour promotion, such as epithelial-mesenchymal transition, cancer stem cell production and drug-resistance. The abnormal activation of YAP/TAZ can affect metastasis-related processes and promote cancer progression and metastasis by interacting with some metastasis-related factors and pathways. In this article, we summarise the evidence that YAP/TAZ regulates breast cancer metastasis, its post-translational modification mechanisms, and the latest advances in the treatment of YAP/TAZ-related breast cancer metastasis, besides providing a new strategy of YAP/TAZ-based treatment of human breast cancer.

The MSC-MCF-7 Duet Playing Tumor Vasculogenesis and Angiogenesis onto the Chick Embryo Chorioallantoic Membrane

BACKGROUND/AIM

Human mesenchymal stem cells (hMSC) represent a versatile cell population, able to modulate the tumor microenvironment. Our aim was to recreate an open scene for the in vivo interaction between hMSC and the MCF-7 breast cancer cells (MCF-7), in order to enlighten the intimate involvement of hMSC in tumor vasculogenesis and angiogenesis.

MATERIALS AND METHODS

hMSC and MCF-7 were seeded onto the chick embryo chorioallantoic membrane (CAM) and incubated for 7 days. Consecutively, the morphology and the immunohistochemical profile of CAM were assessed.

RESULTS

Following this complex interaction, MCF-7 acquired a more aggressive phenotype, hMSC switched to a vascular precursor phenotype, while CAM underwent a major reset to an earlier stage, with hotspots of angiogenesis, vasculogenesis and hematopoiesis.

CONCLUSION

The hallmark of this study was the establishment of a veritable in vivo experimental model of MSC involvement in tumor vasculogenesis and angiogenesis, allowing further analysis in the field.

Association of different patterns of expression of beta-catenin and cyclin D1 with pathogenesis of breast carcinoma

Background

Beta-catenin and cyclin D1 have attracted considerable attention in recent studies as potential proto-oncogenes in many human cancers especially colonic cancer. Beta-catenin plays multiple roles within the cell such as canonical Wnt signaling where cyclin D1 has been identified as one of its target genes. The role of beta-catenin and cyclin D1 in breast cancer has been evaluated in many studies but not established yet.

Materials and Methods

The expression of beta-catenin and cyclin D1 was evaluated in 82 cases of breast carcinoma (BCa) and 32 cases of ductal carcinoma in situ(DCIS) by immunohistochemistry (IHC). Their relationship with clinicopathological features was also investigated. Statistical analysis was done to establish an association.

Results

Abnormal expression of beta-catenin (ABE) was seen in 80.2% cases of invasive ductal carcinoma (IDC) and 47% cases of DCIS, while the cyclin D1 positive expression rate was 60.9% and 50%, respectively. In the cases showing ABE, cyclin D1 positivity was 88.1%. ABE showed significant association with high-grade BCa. The most common pattern of ABE was loss of membrane with nuclear positivity which is associated with worst prognosis. In addition, ABE in cases of BCa and DCIS showed concordant patterns.

Conclusion

Therefore, an association exists between ABE and cyclin D1 in BCa and its precursor lesions implying that Wnt/beta-catenin oncogenic pathway may have a definite role in breast carcinogenesis and can be used for targeted therapy. Also, different patterns of beta-catenin expression may have prognostic and predictive value.

MiR-331-3p Links to Drug Resistance of Pancreatic Cancer Cells by Activating WNT/β-Catenin Signal via ST7L

Background:

Pancreatic cancer is an aggressive type of cancer with poor prognosis, short survival rate, and high mortality. Drug resistance is a major cause of treatment failure in the disease. MiR-331-3p has been reported to play an important role in several cancers. We previously showed that miR-331-3p is upregulated in pancreatic cancer and promotes pancreatic cancer cell proliferation and epithelial-to-mesenchymal transition–mediated metastasis by targeting ST7L. However, it is uncertain whether miR-331-3p is involved in drug resistance.

Methods:

We investigated the relationship between miR-331-3p and pancreatic cancer drug resistance. As part of this, microRNA mimics or inhibitors were transfected into pancreatic cancer cells. Quantitative polymerase chain reaction was used to detect miR-331-3p expression, and flow cytometry was used to detect cell apoptosis. The Cell Counting Kit-8 assay was used to measure the IC50 values of gemcitabine in pancreatic cancer cells. The expression of multidrug resistance protein 1, multidrug resistance-related protein 1, breast cancer resistance protein, β-Catenin, c-Myc, Cyclin D1, Bcl-2, and Caspase-3 was evaluated by Western blotting.

Results:

We confirmed that miR-331-3p is upregulated in gemcitabine-treated pancreatic cancer cells and plasma from chemotherapy patients. We also confirmed that miR-331-3p inhibition decreased drug resistance by regulating cell apoptosis and multidrug resistance protein 1, multidrug resistance-related protein 1, and breast cancer resistance protein expression in pancreatic cancer cells, whereas miR-331-3p overexpression had the opposite effect. We further demonstrated that miR-331-3p effects in drug resistance were partially reversed by ST7L overexpression. In addition, overexpression of miR-331-3p activated Wnt/β-catenin signaling in pancreatic cancer cells, and ST7L overexpression restored activation of Wnt/β-catenin signaling.

Conclusions:

Taken together, our data demonstrate that miR-331-3p contributes to drug resistance by activating Wnt/β-catenin signaling via ST7L in pancreatic cancer cells. These data provide a theoretical basis for new targeted therapies in the future.

Concurrent Wnt pathway component expression in breast and colorectal cancer

Wnt signaling pathway regulates important cell functions such as proliferation and migration and is frequently deregulated in colorectal and breast cancer. Thus, it constitutes an attractive therapeutic target with many drugs being investigated in clinical trials. Eighty-two breast and 102 colorectal carcinomas were analyzed for: relative mRNA expression levels of Wnt pathway components namely Wnt3 ligand, Frizzled 7 receptor and LEF1 transcriptional factor, their concurrent expression patterns and their correlation with clinicopathological features. Regarding breast carcinomas, increased relative mRNA expression levels of WNT3 were found in 54 % of cases whereas decreased relative mRNA expression levels were observed in FZD7 and LEF1 in 82 % and 43 % of cases, respectively. Expression levels of WNT3 were significantly correlated with tumour grade (p = 0.021) in breast cancer. As far as colorectal carcinomas are concerned, increased relative mRNA expression levels of WNT3, FZD7 and LEF1 were found in 60 %, 37 % and 48 % of cases respectively. A statistically significant correlation emerged between LEF1expression levels and pT-category (p = 0.027), suggesting a possible association with tumour aggressiveness in colorectal carcinomas. Statistically significant linear correlations were observed between the expression of WNT3/LEF1 (R = 0.233, p = 0.035) and FZD7/LEF1 (R = 0.359, p = 0.001) in breast carcinomas as well as in colorectal carcinomas (R = 0.536, p < 0.01 and R = 0.210, p = 0.034) respectively. Our results demonstrate a possible clinical significance of Wnt pathway gene expression levels in both tumour types. The distinct expression patterns and simultaneous expression of the investigated genes underscore the complexity of this pathway in breast and colorectal carcinogenesis and highlights the necessity of patient selection with regard to the effectiveness of Wnt pathway inhibitors.

Role of regulatory miRNAs of the Wnt/ β-catenin signaling pathway in tumorigenesis of breast cancer

Breast cancer is the most commonly diagnosed malignancy in women worldwide. Recently, uncontrolled expression of microRNAs was detected in several human disorders like cardiovascular, neurological, intestinal and autoimmunity diseases. MicroRNAs (miRNAs) are now investigated as novel prognostic and diagnostic biomarkers for several solid tumors like breast, lung, and gastrointestinal cancers. Current data suggest that miRNAs are implicated in various oncogenic processes implicated in breast cancer carcinogenesis trough modulating canonical Wnt pathway. Aberrant activation of Wnt/b-catenin signaling was shown to be significantly associated with tumor progression and poor prognosis in patients with breast cancer. This review presents recent findings on the molecular mechanism of microRNAs in regulation of Wnt/β-catenin signaling involved in tumorigenesis of breast cancer.

miR-455-3p Functions as a Tumor Suppressor by Restraining Wnt/β-Catenin Signaling via TAZ in Pancreatic Cancer

Background

Pancreatic cancer (PC) is a highly invasive tumor with a poor prognosis, short overall survival rate and few chemotherapeutic choices. Despite the importance of finding ways to treat pancreatic cancer, the mechanisms of tumor progression have not been fully elucidated. microRNA-455-3p (miR-455-3p) has been reported to play an important role in several cancers, but its function in pancreatic cancer remains unclear.

Methods

To investigate the biological functions, miRNAs mimics or inhibitors were transfected into pancreatic cancer cells. Flow cytometry was used to detect cell apoptosis. Wound healing and Transwell assays were employed to observe cell invasion and migration abilities. The expression of Bcl-2, Bax, caspase-3, E-cadherin, N-cadherin, Snail, β-Catenin, c-Myc and Cyclin D1 were evaluated by qPCR and Western blot.

Results

We confirmed that inhibition of miR-455-3p decreases cell apoptosis and increases cell migration, invasion and EMT of pancreatic cancer, whereas forced overexpression of miR-455-3p has the opposite effect. Furthermore, we demonstrated that the tumor suppression effects of miR-455-3p were partially reversed by TAZ overexpression. In addition, miR-455-3p led to inactivation of Wnt/β-catenin signaling in pancreatic cancer cells, and TAZ overexpression restored the inhibition of Wnt/β-catenin signaling.

Conclusion

Taken together, our data demonstrated that miR-455-3p functions as an important tumor suppressor that suppresses the Wnt/β-catenin signaling pathway via TAZ to inhibit tumor progression in pancreatic cancer. We conclude that the miR-455-3p/TAZ/Wnt axis may be a potential therapeutic target for pancreatic cancer.

3D-microenvironments initiate TCF4 expression rescuing nuclear β-catenin activity in MCF-7 breast cancer cells

Mechanical cues sensed by tumor cells in their microenvironment can influence important mechanisms including adhesion, invasion and proliferation. However, a common mechanosensitive protein and/or pathway can be regulated in different ways among diverse types of tumors. Of particular interest are human breast epithelial cancers, which markedly exhibit a heterogeneous pattern of nuclear β-catenin localization, a protein known to be involved in both mechanotransduction and tumorigenesis. β-catenin can be aberrantly accumulated in the nucleus wherein it binds to and activates lymphoid enhancer factor/T cell factor (LEF/TCF) transcription factors. At present, little is known about how mechanical cues are integrated into breast cancer cells harboring impaired mechanisms of β-catenin's nuclear uptake and/or retention. This prompted us to investigate the influence of mechanical cues on MCF-7 human breast cancer cells which are known to fail in relocating β-catenin into the nucleus due to very low baseline levels of LEF/TCFs. Exploiting three-dimensional (3D) microscaffolds realized by two-photon lithography, we show that surrounding MCF-7 cells have not only a nuclear pool of β-catenin, but also rescue from their defective expression of TCF4 and boost invasiveness. Together with heightened amounts of vimentin, a β-catenin/TCF-target gene regulator of proliferation and invasiveness, such 3D-elicited changes indicate an epithelial-to-mesenchymal phenotypic switch of MCF-7 cells. This is also consistent with an increased in situ MCF-7 cell proliferation that can be abrogated by blocking β-catenin/TCF-transcription activity. Collectively, these data suggest that 3D microenvironments are per se sufficient to prime a TCF4-dependent rescuing of β-catenin nuclear activity in MCF-7 cells. The employed methodology could, therefore, provide a mechanism-based rationale to dissect further aspects of mechanotranscription in breast cancerogenesis, somewhat independent of β-catenin's nuclear accumulation. More importantly, by considering the heterogeneity of β-catenin signaling pathway in breast cancer patients, these data may open alternative avenues for personalized disease management and prevention. STATEMENT OF SIGNIFICANCE: Mechanical cues play a critical role in cancer pathogenesis. Little is known about their influence in breast cancer cells harboring impaired mechanisms of β-catenin's nuclear uptake and/or retention, involved in both mechanotransduction and tumorigenesis. We engineered 3D scaffold, by two-photon lithography, to study the influence of mechanical cues on MCF-7 cells which are known to fail in relocating β-catenin into the nucleus. We found that 3D microenvironments are per se sufficient to prime a TCF4-dependent rescuing of β-catenin nuclear activity that boost cell proliferation and invasiveness. Thus, let us suggest that our system could provide a mechanism-based rationale to further dissect key aspects of mechanotranscription in breast cancerogenesis and progression, somewhat independent of β-catenin's nuclear accumulation.

High MYC mRNA Expression Is More Clinically Relevant than MYC DNA Amplification in Triple-Negative Breast Cancer

DNA abnormalities are used in inclusion criteria of clinical trials for treatments with specific targeted molecules. MYC is one of the most powerful oncogenes and is known to be associated with triple-negative breast cancer (TNBC). Its DNA amplification is often part of the targeted DNA-sequencing panels under the assumption of reflecting upregulated signaling. However, it remains unclear if MYC DNA amplification is a surrogate of its upregulated signaling. Thus, we investigated the difference between MYC DNA amplification and mRNA high expression in TNBCs utilizing publicly available cohorts. MYC DNA amplified tumors were found to have various mRNA expression levels, suggesting that MYC DNA amplification does not always result in elevated MYC mRNA expression. Compared to other subtypes, both MYC DNA amplification and mRNA high expression were more frequent in the TNBCs. MYC mRNA high expression, but not DNA amplification, was significantly associated with worse overall survival in the TNBCs. The TNBCs with MYC mRNA high expression enriched MYC target genes, cell cycle related genes, and WNT/β-catenin gene sets, whereas none of them were enriched in MYC DNA amplified TNBCs. In conclusion, MYC mRNA high expression, but not DNA amplification, reflects not only its upregulated signaling pathway, but also clinical significance in TNBCs.

G0/G1 Switch 2 Induces Cell Survival and Metastasis through Integrin-Mediated Signal Transduction in Human Invasive Breast Cancer Cells

Human breast cancer cell line, MDA-MB-231, is highly invasive and aggressive, compared to less invasive cell line, MCF-7. To explore the genes that might influence the malignancy of MDA-MB-231, DNA microarray analysis was performed. The results showed that G0/G1 switch 2 (G0S2) was one of the most highly expressed genes among the genes upregulated in MDA-MB-231. Although G0S2 acts as a direct inhibitor of adipose triglyceride lipase, action of G0S2 in cancer progression is not yet understood. To investigate whether G0S2 affects invasiveness of MDA-MB-231 cells, G0S2 expression was inhibited using siRNA, which led to decreased cell proliferation, migration, and invasion of MDA-MB-231 cells. Consequently, G0S2 inhibition inactivated integrinregulated FAK-Src signaling, which promoted Hippo signaling and inactivated ERK1/2 signaling. In addition, G0S2 downregulation decreased β-catenin expression, while E-cadherin expression was increased. It was demonstrated for the first time that G0S2 mediates the Hippo pathway and induces epithelial to mesenchymal transition (EMT). Taken together, our results suggest that G0S2 is a major factor contributing to cell survival and metastasis of MDA-MB-231 cells.

Application of in vivo MR methods in the study of breast cancer metabolism

In the last two decades, various in vivo MR methodologies have been evaluated for their potential in the study of cancer metabolism. During malignant transformation, metabolic alterations occur, leading to morphological and functional changes. Among various MR methods, in vivo MRS has been extensively used in breast cancer to study the metabolism of cells, tissues or whole organs. It provides biochemical information at the metabolite level. Altered choline, phospholipid and energy metabolism has been documented using proton (¹ H), phosphorus (³¹ P) and carbon (¹³ C) isotopes. Increased levels of choline-containing compounds, phosphomonoesters and phosphodiesters in breast cancer, which are indicative of altered choline and phospholipid metabolism, have been reported using in vivo, in vitro and ex vivo NMR studies. These changes are reversed on successful therapy, which depends on the treatment regimen given. Monitoring the various tumor intermediary metabolic pathways using nuclear spin hyperpolarization of ¹³ C-labeled substrates by dynamic nuclear polarization has also been recently reported. Furthermore, the utility of various methods such as diffusion, dynamic contrast and perfusion MRI have also been evaluated to study breast tumor metabolism. Parameters such as tumor volume, apparent diffusion coefficient, volume transfer coefficient and extracellular volume ratio are estimated. These parameters provide information on the changes in tumor microstructure, microenvironment, abnormal vasculature, permeability and grade of the tumor. Such changes seen during cancer progression are due to alterations in the tumor metabolism, leading to changes in cell architecture. Due to architectural changes, the tissue mechanical properties are altered; this can be studied using magnetic resonance elastography, which measures the elastic properties of tissues. Moreover, these structural MRI methods can be used to investigate the effect of therapy-induced changes in tumor characteristics. This review discusses the potential of various in vivo MR methodologies in the study of breast cancer metabolism.

Alterations in Wnt- and/or STAT3 signaling pathways and the immune microenvironment during metastatic progression

Metastatic breast cancer is an extremely complex disease with limited treatment options due to the lack of information about the major characteristics of metastatic disease. There is an urgent need, therefore, to understand the changes in cellular complexity and dynamics that occur during metastatic progression. In the current study, we analyzed the cellular and molecular differences between primary tumors and paired lung metastases using a syngeneic p53-null mammary tumor model of basal-like breast cancer. Distinct subpopulations driven by the Wnt- and/or STAT3 signaling pathways were detected in vivo using a lentiviral Wnt- and STAT3 signaling reporter system. A significant increase in the overlapping populations driven by both the Wnt- and STAT3 signaling pathways was observed in the lung metastases as compared to the primary tumors. Furthermore, the overlapping populations showed a higher metastatic potential relative to the other populations and pharmacological inhibition of both signaling pathways was shown to markedly reduce the metastatic lesions in established lung metastases. An analysis of the unique molecular features of the lung metastases revealed a significant association with immune response signatures. Specifically, Foxp3 gene expression was markedly increased and elevated levels of Foxp3 + Treg cells were detected in close proximity to lung metastases. Collectively, these studies illustrate the importance of analyzing intratumoral heterogeneity, changes in population dynamics, and the immune microenvironment during metastatic progression.

Independent Negative Prognostic Role of TCF1 Expression within the Wnt/β-Catenin Signaling Pathway in Primary Breast Cancer Patients

The Wnt pathway is involved in the progression of breast cancer (BC). We aimed to evaluate the expression of some components of the Wnt pathway (β-catenin, FZD4 (frizzled receptor 4), LRP5 (low-density lipoprotein receptor-related protein 5), LRP6, and TCF1 (T-cell factor 1)) to detect potential associations with NHERF1 (Na+/H+ exchanger regulatory factor 1) protein. Besides, we assessed their impact on patients’ clinical outcome. We evaluated 220 primary BC samples by immunohistochemistry (IHC) and protein localization by immunofluorescence. We found a significant correlation between NHERF1 and FZD4, LRP5, LRP6, and TCF1. Univariate analysis showed that the overexpression of β-catenin (p < 0.0001), FZD4 (p = 0.0001), LRP5, LRP6, and TCF1 (p < 0.0001 respectively) was related to poor disease-free survival (DFS). A Kaplan-Meier analysis confirmed univariate data and showed a poor DFS for cNHERF1+/FZD4+ (p = 0.0007), cNHERF1+/LRP5+ (p = 0.0002), cNHERF1+/LRP6+ (p < 0.0001), and cNHERF1+/TCF1+ phenotypes (p = 0.0034). In multivariate analysis, the expression of TCF1 and β-catenin was an independent prognostic variable of worse DFS (p = 0.009 and p = 0.027, respectively). In conclusion, we found that the overexpression of β-catenin, FZD4, LRP5, LRP6, and TCF1 was associated with poor prognosis. Furthermore, we first identified TCF1 as an independent prognostic factor of poor outcome, indicating it as a new potential biomarker for the management of BC patients. Also, the expression of Wnt pathway proteins, both alone and in association with NHERF1, suggests original associations of biological significance for new studies.

Wnt Signaling in Cancer Metabolism and Immunity

The Wingless (Wnt)/β-catenin pathway has long been associated with tumorigenesis, tumor plasticity, and tumor-initiating cells called cancer stem cells (CSCs). Wnt signaling has recently been implicated in the metabolic reprogramming of cancer cells. Aberrant Wnt signaling is considered to be a driver of metabolic alterations of glycolysis, glutaminolysis, and lipogenesis, processes essential to the survival of bulk and CSC populations. Over the past decade, the Wnt pathway has also been shown to regulate the tumor microenvironment (TME) and anti-cancer immunity. Wnt ligands released by tumor cells in the TME facilitate the immune evasion of cancer cells and hamper immunotherapy. In this review, we illustrate the role of the canonical Wnt/β-catenin pathway in cancer metabolism and immunity to explore the potential therapeutic approach of targeting Wnt signaling from a metabolic and immunological perspective.

Knockdown of PTOV1 and PIN1 exhibit common phenotypic anti-cancer effects in MDA-MB-231 cells

Background

Earlier, we have identified PTOV1 as a novel interactome of PIN1 in PC-3 cells. This study aims to explore the functional similarity and the common role of both genes in breast cancer cell proliferation.

Methods

CTG, crystal violet assay, clonogenic assay, wound healing assay, cell cycle analysis, Hoechst staining and ROS measurement were performed to assess cell viability, colony forming potential, cell cycle arrest, nuclear condensation and ROS production after knocking down of PTOV1 and PIN1 by siRNAs in MDA-MB-231 and MCF-7 cells. CO-IP, qPCR and western blot were performedto study interaction, transcriptional and translational regulation of both genes.

Results

Knockdown of PTOV1 and PIN1 inhibited the cell proliferation, colony formation, migration, cell cycle, and induced nuclear condensation as well as ROS production. Interaction of PTOV1 and PIN1 was validated by Co-IP in MDA-MB-231 cells. Genes involved in cell proliferation, migration, cell cycle, and apoptosis were regulated by PIN1 and PTOV1. PTOV1 knockdown inhibited Bcl-2, Bcl-xL and inducedBAX, LC3 and Beclin-1expression. Overexpression of PIN1 increased the expression of PTOV1. Knockdown of both genes inhibited the expression of cyclin D1, c-Myc, and β-catenin.

Conclusions

PTOV1 and PIN1 interact and exert oncogenic role in MDA-MB-231 cells by sharing the similar expression profile at transcriptional and translational level which can be a promising hub for therapeutic target.

G-Alpha Subunit Abundance and Activity Differentially Regulate β-Catenin Signaling

Heterotrimeric G proteins are signal transduction proteins involved in regulating numerous signaling events. In particular, previous studies have demonstrated a role for G-proteins in regulating β-catenin signaling. However, the link between G-proteins and β-catenin signaling is controversial and appears to depend on G-protein specificity. We describe a detailed analysis of a link between specific G-alpha subunits and β-catenin using G-alpha subunit genetic knockout and knockdown approaches. The Pasteurella multocida toxin was utilized as a unique tool to activate G-proteins, with LiCl treatment serving as a β-catenin signaling agonist. The results show that Pasteurella multocida toxin (PMT) significantly enhanced LiCl-induced active β-catenin levels in HEK293T cells and mouse embryo fibroblasts. Evaluation of the effect of specific G-alpha proteins on the regulation of β-catenin showed that G_q/11 and G_12/13 knockout cells had significantly higher levels of active and total β-catenin than wild-type cells. The stimulation of active β-catenin by PMT and LiCl was lost upon both constitutive and transient knockdown of G₁₂ and G₁₃ but not G_q Based on our results, we conclude that endogenous G-alpha proteins are negative regulators of active β-catenin; however, PMT-activated G-alpha subunits positively regulate LiCl-induced β-catenin expression in a G_12/13-dependent manner. Hence, G-alpha subunit regulation of β-catenin is context dependent.

Activation of Epithelial-Mesenchymal Transition and Altered β-Catenin Signaling in a Novel Indian Colorectal Carcinoma Cell Line

Colorectal cancer is the third major cause of cancer-related mortality worldwide. The upward trend in incidence and mortality rates, poor sensitivity to conventional therapies and a dearth of early diagnostic parameters pose a huge challenge in the management of colorectal cancer in India. Due to the high level of genetic diversity present in the Indian population, unraveling the genetic contributions toward pathogenesis is key for understanding the etiology of colorectal cancer and in reversing this trend. We have established a novel cell line, MBC02, from an Indian colorectal cancer patient and have carried out extensive molecular characterization to unravel the pathological alterations in this cell line. In-depth molecular analysis of MBC02 revealed suppression of E-cadherin expression, concomitant with overexpression of EMT related molecules, which manifested in the form of highly migratory and invasive cells. Loss of membrane-tethered E-cadherin released β-catenin from the adherens junction resulting in its cytoplasmic and nuclear accumulation and consequently, upregulation of c-Myc. MBC02 also showed dramatic transcriptional upregulation of β-catenin. Remarkably, we observed significantly elevated proteasome activity that perhaps co-evolved to compensate for the unnaturally high mRNA level of β-catenin to regulate the increased protein load. In addition, there was substantial misregulation of other clinically relevant signaling pathways that have clinical relevance in the pathogenesis of colorectal cancer. Our findings pave the way toward understanding the molecular differences that could define pathogenesis in cancers originating in the Indian population.

miR-135 regulated breast cancer proliferation and epithelial-mesenchymal transition acts by the Wnt/β-catenin signaling pathway

Breast cancer (BC) is the most common cancer in women around the world. microRNAs (miRNAs/miRs) have been proved to be associated with the development and progression of breast cancer. In the present study, to elucidate the effects of dysregulated miR‑135 on cells and underlying mechanisms in BC, in vitro and in vivo experiments were conducted. The biological functions of miR‑135 were studied using MTT, colony formation, wound healing, transwell assays as well as tumorigenicity analysis. Gain‑ and loss‑ of function of miR‑135 studies revealed that ectopic expression of miR‑135 in MDA‑MB‑468 and MCF‑7 cells significantly inhibited cell growth, migration, invasion and EMT, at least in part through inhibiting the activation of the Wnt/β‑catenin pathway. Moreover, this was reversed in cells which were transfected with miR‑135 inhibitors. Taken together, the results of the present study provided evidence that miR‑135 acted as a tumor suppressor in BC, which may represent a novel therapeutic strategy for the diagnosis and prognosis of BC.

Galectin-3 and β-catenin are associated with a poor prognosis in serous epithelial ovarian cancer

Purpose

This study was designed to explore the expression levels of Galectin-3 (Gal-3) and β-catenin in serous epithelial ovarian cancer (SEOC), the linkage between their expressions, and the clinicopathological features of SEOC patients.

Patients and methods

Seventy-four SEOC patients' specimens were detected for Gal-3 and β-Catenin expressions using immunohistochemistry, and the association between β-catenin or Gal-3 protein expressions and clinicopathological features, treatment effects, and prognosis were analyzed using SPSS 19.0. Western blot was used to analyze protein expressions of Wnt/β-catenin pathway in ovarian cancer cell lines.

Results

There was a statistically significant positive correlation between Gal-3 and β-catenin expressions in SEOC (r=0.304 and P=0.001). Gal-3 expression was related to the grade (P=0.037), clinical stage (P=0.034), platinum resistance (P=0.030), and recurrence (P=0.001) in SEOC. There was a significant correlation between β-catenin with recurrence in SEOC (P=0.035). Platinum resistance (P=0.003) and Gal-3 expression (P<0.001) were independent risk factors for poorer overall survival (OS). OS of the strongly positive Gal-3 group was significantly lower than that of the negative and weakly positive groups (log-rank test, P=0.001). OS of the positive β-catenin group was lower than that of the negative β-catenin group (log-rank test, P=0.034). Downregulating Gal-3 expression attenuated the protein expressions of Wnt/β-catenin pathway in ovarian cancer cell lines.

Conclusion

Gal-3 might activate Wnt/β-catenin signaling pathway in SEOC. Hence, Gal-3 may serve as a prognostic factor for SEOC. Targeting Gal-3 may be a promising new treatment approach for SEOC.

Re-Evaluating E-Cadherin and β-Catenin: A Pan-Cancer Proteomic Approach with an Emphasis on Breast Cancer

E-cadherin is conventionally considered to be a good prognostic marker in cancer. The loss of E-cadherin is one of the key hallmarks of epithelial-to-mesenchymal transition, a biological process that promotes cancer cell invasiveness and metastasis. Recent evidence has cast doubt on the importance of epithelial-to-mesenchymal transition in metastasis. The availability of protein-level data in the Cancer Genome Atlas allows for the quantitative analysis of protein and prognosis. The prognostic values of E-cadherin and β-catenin were revisited across 19 cancer types, and high E-cadherin was found to correlate with good prognosis in most cancers. Conversely, higher E-cadherin and β-catenin correlated with shorter survival in invasive breast carcinoma. Stratifying breast cancers by histologic subtype revealed that the poor prognosis of E-cadherin and β-catenin proteins was characteristic of infiltrating ductal, but not lobular, carcinomas. To further corroborate the protein findings and examine cellular localization, immunohistochemistry was used for E-cadherin and β-catenin in 163 breast patient samples from the Iowa cohort. Most previous studies showing that reduced or absent E-cadherin and β-catenin was inversely associated with tumor stages in ductal carcinomas were confirmed. Taken together, these results lead us to question the prognostic values of E-cadherin and β-catenin in ductal carcinomas and indicate a complicated role of E-cadherin and β-catenin in breast cancer progression.

Preferential Inhibition of Wnt/β-Catenin Signaling by Novel Benzimidazole Compounds in Triple-Negative Breast Cancer

Wnt/β-catenin signaling is upregulated in triple-negative breast cancer (TNBC) compared to other breast cancer subtypes and normal tissues. Current Wnt/β-catenin inhibitors, such as niclosamide, target the pathway nonspecifically and exhibit poor pharmacokinetics/pharmacodynamics in vivo. Niclosamide targets other pathways, including mTOR, STAT3 and Notch. Novel benzimidazoles have been developed to inhibit Wnt/β-catenin signaling with greater specificity. The compounds SRI33576 and SRI35889 were discovered to produce more cytotoxicity in TNBC cell lines than in noncancerous cells. The agents also downregulated Wnt/β-catenin signaling mediators LRP6, cyclin D1, survivin and nuclear active β-catenin. In addition, SRI33576 did not affect mTOR, STAT3 and Notch signaling in TNBC and noncancerous cells. SRI35889 inhibited mTOR signaling less in noncancerous than in cancerous cells, while not affecting STAT3 and Notch pathways. Compounds SRI32529, SRI35357 and SRI35361 were not selectively cytotoxic against TNBC cell lines compared to MCF10A cells. While SRI32529 inhibited Wnt/β-catenin signaling, the compound also mitigated mTOR, STAT3 and Notch signaling. SRI33576 and SRI35889 were identified as cytotoxic and selective inhibitors of Wnt/β-catenin signaling with therapeutic potential to treat TNBC in vivo.

R-spondin3 Is Associated with Basal-Progenitor Behavior in Normal and Tumor Mammary Cells

R-spondin3 (RSPO3) is a member of a family of secreted proteins that enhance Wnt signaling pathways in diverse processes, including cancer. However, the role of RSPO3 in mammary gland and breast cancer development remains unclear. In this study, we show that RSPO3 is expressed in the basal stem cell-enriched compartment of normal mouse mammary glands but is absent from committed mature luminal cells in which exogenous RSPO3 impairs lactogenic differentiation. RSPO3 knockdown in basal-like mouse mammary tumor cells reduced canonical Wnt signaling, epithelial-to-mesenchymal transition-like features, migration capacity, and tumor formation in vivo Conversely, RSPO3 overexpression, which was associated with some LGR and RUNX factors, highly correlated with the basal-like subtype among patients with breast cancer. Thus, we identified RSPO3 as a novel key modulator of breast cancer development and a potential target for treatment of basal-like breast cancers.Significance: These findings identify RSPO3 as a potential therapetuic target in basal-like breast cancers.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/16/4497/F1.large.jpg Cancer Res; 78(16); 4497-511. ©2018 AACR.

Deregulation of E-cadherin, β-catenin, APC and Caveolin-1 expression occurs in canine prostate cancer and metastatic processes

Prostate cancer is a heterogeneous disease with high levels of clinical and gene heterogeneity, consequently offering several targets for therapy. Dogs with naturally occurring prostate cancer are useful models for molecular investigations and studying new treatment efficacy. Three genes and proteins associated with the WNT pathway (β-catenin, APC and E-cadherin) and Caveolin-1 (CAV-1) were evaluated in canine pre-neoplastic proliferative inflammatory atrophy (PIA), prostate cancer and metastatic disease. The APC gene methylation status was also investigated. As in human prostate cancer, cytoplasmic and nuclear β-catenin, which are fundamental for activating the canonical WNT pathway, were found in canine prostate cancer and metastasis. Membranous E-cadherin was also lost in these lesions, allowing cellular migration to the stroma and nuclear localization of β-catenin. In contrast to human prostate tumours, no APC downregulation or hypermethylation was found in canine prostate cancer. The CAV-1 gene and protein overexpression were found in canine prostate cancer, and as in humans, the highest levels were found in Gleason scores ≥8. In conclusion, as with human prostate cancer, β-catenin and E-cadherin in the WNT pathway, as well as Caveolin-1, are molecular drivers in canine prostate cancer. These findings provide additional evidence that dogs are useful models for studying new therapeutic targets in prostate cancer.

Tumor-infiltrating lymphocytes are associated with β-catenin overexpression in breast cancer

BACKGROUND

Inhibition of lymphocytes infiltration and activity may impair antitumor immune response and limit treatment responsiveness. Wnt/β-catenin pathway has been suggested to contribute to immune evasion in tumor by suppressing the function of immune cells and excluding T cell infiltration. However, the effects of Wnt/β-catenin on TILs recruitment remain controversial.

OBJECTIVE

We aimed to investigate whether intratumoral Wnt/β-catenin signaling could affect the lymphocyte infiltration in breast cancer.

METHODS

The distribution of stromal TILs, CD8+ and FOXP3+ TIL subsets, and the expression of β-catenin were separately assessed on consecutive sections of 96 breast cancer specimens.

RESULTS

Both stromal infiltrated TILs and β-catenin expression were upregulated in hormone receptor negative HER2-enriched and TNBC subtypes. Furthermore, high levels of stromal TILs as well as CD8+ or FOXP3+ TIL subsets were associated with β-catenin overexpression by breast cancer, respectively.

CONCLUSIONS

For the first time, we demonstrated that rather than excluding lymphocytes infiltration as reported in mela-noma, high levels of TILs were associated with β-catenin overexpression in BC. Wnt/β-catenin signaling may play a critical role in BC immunity, particularly in HER2-enriched and triple negative BC, and may serve as a potential target for regulating immune infiltrates in breast cancer.

MicroRNA-1229 overexpression promotes cell proliferation and tumorigenicity and activates Wnt/β-catenin signaling in breast cancer

Constitutive activation of the Wnt/β-catenin pathway promotes malignant proliferation and it is inversely correlated with the prognosis of patients with breast cancer. However, mutations in key regulators, such as APC, Axin and β-catenin, contribute to aberrant activation of the Wnt/β-catenin signaling pathway in various cancers, but rarely found in breast cancer, suggesting that other mechanisms might be involved in the activation of Wnt/β-catenin signaling in breast cancer. In the present study, we found that miR-1229 expression was markedly upregulated in breast cancer and associated with poor survival. Overexpressing miR-1229 promoted while inhibiting miR-1229 reduced, proliferation of breast cancer cell proliferation in vitro and tumor growth in vivo. Furthermore, we found that overexpression of miR-1229 activated the Wnt/β-catenin signaling pathway in breast cancer by directly targeting the multiple important negative regulators of Wnt/β-catenin signaling, including adenomatous polyposis coli (APC), glycogen synthase kinase-3β (GSK-3β), and inhibitor of β-catenin and T cell factor (ICAT). Taken together, our results suggest that miR-1229 plays an important role in promotion breast cancer progression and may represent a novel therapeutic target in breast cancer.

High-frequency deregulated expression of Wnt signaling pathway members in breast carcinomas

Purpose

Breast carcinoma is the most common malignancy and leading cause of cancer-related deaths in women worldwide including Saudi Arabia. Breast cancer in Saudi women develops at a much early age with median age of onset of 49 years compared to 62 years observed in patients from USA. Aberrations in wingless and integration site growth factor (Wnt) signaling pathway have been pathologically implicated in development of breast cancers and hence its role was examined in Saudi patients.

Materials and methods

We immunohistochemically examined various components of Wnt signaling pathway including β-catenin, tumor suppressor proteins, adenomatous polyposis coli (APC), and Axin, expression of naturally occurring pathway antagonists such as Dickkopf Wnt signaling pathway inhibitor 3 (DKK3), FRP2, and WIF1, as well as Wnt target cyclin D1 and c-Myc to establish if the pathway is constitutively activated in breast cancers arising in Saudi women.

Results

Cytoplasmic β-catenin, indicative of activation of the pathway, was observed in 24% of cases. Expression of APC and Axin, which are components of β-catenin destruction complex, was lost in 5% and 10% of tumors, respectively. Additionally, Wnt signaling inhibitors DKK3, FRP2, and Wnt inhibitory factor 1 (WIF1) were not expressed in 8%, 14%, and 5% breast tumors, respectively. Overall, accumulation of cytoplasmic β-catenin and downregulation of other Wnt pathway proteins (APC/Axin/DKK3/FRP2/WIF1) were found in approximately half of the breast cancers (47%) in our cohort. Consistent with this, analysis of Wnt target genes demonstrated moderate-to-strong expression of c-Myc in 58% and cyclin D1 in 50% of breast cancers. Deregulation of Wnt pathway was not associated with age of onset of the disease, tumor grade, and triple-negative status of breast cancers.

Conclusions

High level of deregulated expression of Wnt pathway proteins suggests its important role in pathogenesis of breast cancers arising in Saudi women who may benefit from development of therapeutic drugs targeting this pathway.

Breast cancer lung metastasis: Molecular biology and therapeutic implications

Distant metastasis accounts for the vast majority of deaths in patients with cancer. Breast cancer exhibits a distinct metastatic pattern commonly involving bone, liver, lung, and brain. Breast cancer can be divided into different subtypes based on gene expression profiles, and different breast cancer subtypes show preference to distinct organ sites of metastasis. Luminal breast tumors tend to metastasize to bone while basal-like breast cancer (BLBC) displays a lung tropism of metastasis. However, the mechanisms underlying this organ-specific pattern of metastasis still remain to be elucidated. In this review, we will summarize the recent advances regarding the molecular signaling pathways as well as the therapeutic strategies for treating breast cancer lung metastasis.

Cancer cell-soluble factors reprogram mesenchymal stromal cells to slow cycling, chemoresistant cells with a more stem-like state

BACKGROUND

Mesenchymal stem cells (MSCs) play different roles in modulating tumor progression, growth, and metastasis. MSCs are recruited to the tumor site in large numbers and subsequently have an important microenvironmental role in modulating tumor progression and drug sensitivity. However, the effect of the tumor microenvironment on MSC plasticity remains poorly understood. Herein, we report a paracrine effect of cancer cells, in which they secrete soluble factors that promote a more stem-like state in bone marrow mesenchymal stem cells (BM-MSCs).

METHODS

The effect of soluble factors secreted from MCF7, Hela, and HepG2 cancer cell lines on BM-MSCs was assessed using a Transwell indirect coculture system. After 5 days of coculture, BM-MSCs were characterized by flow cytometry for surface marker expression, by qPCR for gene expression profile, and by confocal immunofluorescence for marker expression. We then measured the sensitivity of cocultured BM-MSCs to chemotherapeutic agents, their cell cycle profile, and their response to DNA damage. The sphere formation, invasive properties, and in-vivo performance of BM-MSCs after coculture with cancer cells were also measured.

RESULTS

Indirect coculture of cancer cells and BM-MSCs, without direct cell contact, generated slow cycling, chemoresistant spheroid stem cells that highly expressed markers of pluripotency, cancer cells, and cancer stem cells (CSCs). They also displayed properties of a side population and enhanced sphere formation in culture. Accordingly, these cells were termed cancer-induced stem cells (CiSCs). CiSCs showed a more mesenchymal phenotype that was further augmented upon TGF-β stimulation and demonstrated a high expression of the β-catenin pathway and ALDH1A1.

CONCLUSIONS

These findings demonstrate that MSCs, recruited to the tumor microenvironment in large numbers, may display cellular plasticity, acquire a more stem-like state, and acquire some properties of CSCs upon exposure to cancer cell-secreted factors. These acquired characteristics may contribute to tumor progression, survival, and metastasis. Our findings provide new insights into the interactions between MSCs and cancer cells, with the potential to identify novel molecular targets for cancer therapy.

Wnt/β-catenin Signaling Contributes to Tumor Malignancy and Is Targetable in Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumor (GIST) is the most common type of sarcoma and usually harbors either a KIT or PDGFRA mutation. However, the molecular basis for tumor malignancy is not well defined. Although the Wnt/β-catenin signaling pathway is important in a variety of cancers, its role in GIST is uncertain. Through analysis of nearly 150 human GIST specimens, we found that some human GISTs expressed β-catenin and contained active, dephosphorylated nuclear β-catenin. Furthermore, advanced human GISTs expressed reduced levels of the Wnt antagonist DKK4. Accordingly, in human GIST T1 cells, Wnt stimulation increased β-catenin-mediated transcriptional activity in a reporter assay as well as transcription of the downstream target genes Axin2 and CCND1 In contrast, DKK4 overexpression in GIST T1 cells reduced Wnt/β-catenin signaling. In addition, we showed that nuclear β-catenin stability was partially regulated by the E3 ligase COP1, as demonstrated with coimmunoprecipitation and COP1 knockdown. Three molecular inhibitors of the Wnt/β-catenin pathway demonstrated antitumor efficacy in various GIST models, both in vitro and in vivo Notably, the tankyrase inhibitor G007-LK alone had substantial activity against tumors of genetically engineered Kit^V558Δ/+ mice, and the effect was increased by the addition of the Kit inhibitor imatinib mesylate. Collectively, our findings demonstrate that Wnt/β-catenin signaling is a novel therapeutic target for selected untreated or imatinib-resistant GISTs. Mol Cancer Ther; 16(9); 1954-66. ©2017 AACR.