Molecular characterization of the tumor-suppressive function of nischarin in breast cancer

Preliminary investigation on the mechanism of baicalein regulating the effects of Nischarin on invasion and apoptosis of human breast cancer cells MCF-7 through Wnt3α/β-catenin pathway

BACKGROUND

Breast cancer (BC) remains the leading cause of cancer-related mortality in women. Here, we investigate the anti-tumor effects of baicalein on human BC cells (MCF-7 cells) and explore if it regulates the Nischarin protein via Wnt3α/β-catenin signaling pathway.

METHODS

We employed Wnt3α and DKK-1 to activate and inhibit the Wnt/β-catenin signaling pathway, respectively. We used CCK-8 cell viability, flow cytometry apoptosis, wound-healing and transwell migration/invasion assays. Further, using western blotting and real-time quantitative PCR (q-PCR) we analyzed expression levels of Nischarin, MMP-9, Wnt/β-catenin pathway (β-catenin, Axin 1), and apoptotic pathway (Bax, Bcl-2) proteins and their mRNAs.

RESULTS

We found that baicalein inhibits MCF-7 cell viability and promotes apoptosis (evidenced by increased Bax and decreased Bcl-2 expressions) in a concentration-dependent manner. It also inhibits TPA-induced migration and invasion, and downregulates MMP-9 expression. Baicalein reverses the increase in cell viability caused by Wnt3α-induced Wnt/β-catenin pathway activation. Conversely, baicalein counteracts the increase in apoptosis caused by DKK-1 mediated inhibition of the Wnt/β-catenin pathway. Additionally, baicalein upregulates Nischarin expression via modulating the Wnt/β-catenin pathway as indicated by the antagonistic effects of Wnt3α and DKK-1 on this effect of baicalein.

CONCLUSION

Baicalein exerts anti-tumor effects on MCF-7 cells through the Wnt3α/β-catenin signaling pathway, and promotes apoptosis and inhibits migration and invasion. The upregulation of Nischarin by baicalein further suggests a potential therapeutic target for BC treatment.

UBTF mediates activation of L3MBTL2 to suppress NISCH expression through histone H2AK119 monoubiquitination modification in breast cancer

Lethal(3)malignant brain tumor-like protein 2 (L3MBTL2) has been related to transcriptional inhibition and chromatin compaction. Nevertheless, the biological functions and mechanisms of L3MBTL2 are undefined in breast cancer (BRCA). Here, we revealed that L3MBTL2 is responsible for the decline of Nischarin (NISCH), a well-known tumor suppressor, in BRCA, and explored the detailed mechanism. Knockdown of L3MBTL2 reduced monoubiquitination of histone H2A at lysine-119 (H2AK119ub), leading to reduced binding to the NISCH promoter and increased expression of NISCH. Meanwhile, the knockdown of L3MBTL2 decreased proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of BRCA cells, and increased apoptosis, which were abated by NISCH knockdown. Nucleolar transcription factor 1 (UBTF) induced the transcription of L3MBTL2 in BRCA, and the suppressing effects of UBTF silencing on EMT in BRCA cells were also reversed by NISCH knockdown. Knockdown of UBTF slowed tumor progression and attenuated lung tumor infiltration, whereas simultaneous knockdown of NISCH accelerated EMT and increased tumor lung metastasis. Taken together, our results show that L3MBTL2, transcriptionally activated by UBTF, exerts oncogenic functions in BRCA, by catalyzing H2AK119Ub and reducing expression of NISCH.

Nischarin inhibits the epithelial-mesenchymal transition process and angiogenesis in breast cancer cells by inactivating FAK/ERK signaling pathway via EGF like repeats and discoidin domains 3

BACKGROUND

Our previous study has demonstrated that Nischarin (NISCH) exerts its antitumor effects in breast cancer (BC) by suppressing cell migration and invasion. This study aims to explore the underlying mechanism through which NISCH functions in BC.

METHODS AND RESULTS

The relevance between EGF Like Repeats and Discoidin Domains 3 (EDIL3) mRNA expression and the overall survival of tumor patients was depicted by the Kaplan-Meier curve. The findings revealed that overexpressed NISCH attenuated cell motility and colony-forming capacities of Hs578T cells, yet silenced NISCH in MDA-MB-231 cells led to contrasting results. Western blot (WB) analysis indicated that overexpression of NISCH significantly down-regulated the Vimentin and Slug expression, and inactivated the FAK/ERK signaling pathway. RNA sequencing (RNA-seq) was performed in NISCH-overexpressed Hs578T cells and the control cells to analyze differentially expressed genes (DeGs), and the results showed a significant down-regulation of EDIL3 mRNA level upon overexpression of NISCH. Subsequent functional analyses demonstrated that overexpression of EDIL3 attenuated the inhibitory effect of NISCH on cell migration, invasion, colony formation, and tube formation.

CONCLUSION

In summary, our finding preliminarily revealed that NISCH inhibits the epithelial-mesenchymal transition (EMT) process and angiogenesis in BC cells by down-regulating EDIL3 to inactivate the FAK/ERK signaling pathway, thereby suppressing the progression of BC. Our results hold promise for contributing to the deep understanding of BC pathogenesis and identifying new therapeutic strategies for clinical application.

Analysis of the nischarin expression across human tumor types reveals its context-dependent role and a potential as a target for drug repurposing in oncology

Nischarin was reported to be a tumor suppressor that plays a critical role in breast cancer initiation and progression, and a positive prognostic marker in breast, ovarian and lung cancers. Our group has found that nischarin had positive prognostic value in female melanoma patients, but negative in males. This opened up a question whether nischarin has tumor type-specific and sex-dependent roles in cancer progression. In this study, we systematically examined in the public databases the prognostic value of nischarin in solid tumors, regulation of its expression and associated signaling pathways. We also tested the effects of a nischarin agonist rilmenidine on cancer cell viability in vitro. Nischarin expression was decreased in tumors compared to the respective healthy tissues, most commonly due to the deletions of the nischarin gene and promoter methylation. Unlike in healthy tissues where it was located in the cytoplasm and at the membrane, in tumor tissues nischarin could also be observed in the nuclei, implying that nuclear translocation may also account for its cancer-specific role. Surprisingly, in several cancer types high nischarin expression was a negative prognostic marker. Gene set enrichment analysis showed that in tumors in which high nischarin expression was a negative prognostic marker, signaling pathways that regulate stemness were enriched. In concordance with the findings that nischarin expression was negatively associated with pathways that control cancer growth and progression, nischarin agonist rilmenidine decreased the viability of cancer cells in vitro. Taken together, our study lays a ground for functional studies of nischarin in a context-dependent manner and, given that nischarin has several clinically approved agonists, provides rationale for their repurposing, at least in tumors in which nischarin is predicted to be a positive prognostic marker.

Nischarin expression may have differing roles in male and female melanoma patients

Due to the development of resistance to previously effective therapies, there is a constant need for novel treatment modalities for metastatic melanoma. Nischarin (NISCH) is a druggable scaffolding protein reported as a tumor suppressor and a positive prognostic marker in breast and ovarian cancers through regulation of cancer cell survival, motility and invasion. The aim of this study was to examine the expression and potential role of nischarin in melanoma. We found that nischarin expression was decreased in melanoma tissues compared to the uninvolved skin, and this was attributed to the presence of microdeletions and hyper-methylation of the NISCH promoter in the tumor tissue. In addition to the previously reported cytoplasmic and membranous localization, we observed nischarin in the nuclei in melanoma patients' tissues. NISCH expression in primary melanoma had favorable prognostic value for female patients, but, unexpectedly, high NISCH expression predicted worse prognosis for males. Gene set enrichment analysis suggested significant sex-related disparities in predicted association of NISCH with several signaling pathways, as well as with different tumor immune infiltrate composition in male and female patients. Taken together, our results imply that nischarin may have a role in melanoma progression, but that fine-tuning of the pathways it regulates is sex-dependent. KEY MESSAGES: Nischarin is a tumor suppressor whose role has not been investigated in melanoma. Nischarin expression was downregulated in melanoma tissue compared to the normal skin. Nischarin had the opposite prognostic value in male and female melanoma patients. Nischarin association with signaling pathways differed in females and males. Our findings challenge the current view of nischarin as a universal tumor suppressor.

Targeting Mcl-1 by a small molecule NSC260594 for triple-negative breast cancer therapy

Triple-negative breast cancers (TNBCs) are aggressive forms of breast cancer and tend to grow and spread more quickly than most other types of breast cancer. TNBCs can neither be targeted by hormonal therapies nor the antibody trastuzumab that targets the HER2 protein. There are urgent unmet medical needs to develop targeted drugs for TNBCs. We identified a small molecule NSC260594 from the NCI diversity set IV compound library. NSC260594 exhibited dramatic cytotoxicity in multiple TNBCs in a dose-and time-dependent manner. NSC260594 inhibited the Myeloid cell leukemia-1 (Mcl-1) expression through downregulation of Wnt signaling proteins. Consistent with this, NSC260594 treatment increased apoptosis, which was confirmed by using an Annexin-V/PI assay. Interestingly, NSC260594 treatment reduced the cancer stem cell (CSC) population in TNBCs. To make NSC260594 more clinically relevant, we treated NSC260594 with TNBC cell derived xenograft (CDX) mouse model, and with patient-derived xenograft (PDX) organoids. NSC260594 significantly suppressed MDA-MB-231 tumor growth in vivo, and furthermore, the combination treatment of NSC260594 and everolimus acted synergistically to decrease growth of TNBC PDX organoids. Together, we found that NSC260594 might serve as a lead compound for triple-negative breast cancer therapy through targeting Mcl-1.

Interaction between Long Noncoding RNAs and Syncytin-1/Syncytin-2 Genes and Transcripts: How Noncoding RNAs May Affect Pregnancy in Patients with Systemic Lupus Erythematosus

BACKGROUND

Patients with systemic lupus erythematosus (SLE) often suffer from obstetric complications not necessarily associated with the antiphospholipid syndrome. These events may potentially result from the reduced placental synthesis of the fusogenic proteins syncytin-1 and syncytin-2, observed in women with pregnancy-related disorders. SLE patients have an aberrant noncoding (nc)RNA signature that may in turn dysregulate the expression of syncytin-1 and syncytin-2 during placentation. The aim of this research is to computationally evaluate and characterize the interaction between syncytin-1 and syncytin-2 genes and human ncRNAs and to discuss the potential implications for SLE pregnancy adverse outcomes.

METHODS

The FASTA sequences of the syncytin-1 and syncytin-2 genes were used as inputs to the Ensembl.org library to find any alignments with human ncRNA genes and their transcripts, which were characterized for their tissue expression, regulatory activity on adjacent genes, biological pathways, and potential association with human disease.

RESULTS

BLASTN analysis revealed a total of 100 hits with human long ncRNAs (lncRNAs) for the syncytin-1 and syncytin-2 genes, with median alignment scores of 151 and 66.7, respectively. Only lncRNAs TP53TG1, TTTY14, and ENSG00000273328 were reported to be expressed in placental tissue. Dysregulated expression of lncRNAs TP53TG1, LINC01239, and LINC01320 found in this analysis has previously been described in SLE patients as well as in women with a high-risk pregnancy. In addition, some of the genes adjacent to lncRNAs aligned with syncytin-1 or syncytin-2 in a regulatory region might increase the risk of pregnancy complications or SLE.

CONCLUSIONS

This is the first computational study showing alignments between syncytin-1 and syncytin-2 genes and human lncRNAs. Whether this mechanism affects syncytiotrophoblast morphogenesis in SLE females is unknown and requires further investigation.

Ceritinib is a novel triple negative breast cancer therapeutic agent

BACKGROUND

Triple-negative breast cancers (TNBCs) are clinically aggressive subtypes of breast cancer. TNBC is difficult to treat with targeted agents due to the lack of commonly targeted therapies within this subtype. Androgen receptor (AR) has been detected in 12-55% of TNBCs. AR stimulates breast tumor growth in the absence of estrogen receptor (ER), and it has become an emerging molecular target in TNBC treatment.

METHODS

Ceritinib is a small molecule inhibitor of tyrosine kinase and it is used in the therapy of non-small lung cancer patients. Enzalutamide is a small molecule compound targeting the androgen receptor and it is used to treat prostate cancer. Combination therapy of these drugs were investigated using AR positive breast cancer mouse xenograft models. Also, combination treatment of ceritinib and paclitaxel investigated using AR- and AR low mouse xenograft and patient derived xenograft models.

RESULTS

We screened 133 FDA approved drugs that have a therapeutic effect of AR+ TNBC cells. From the screen, we identified two drugs, ceritinib and crizotinib. Since ceritinib has a well- defined role in androgen independent AR signaling pathways, we further investigated the effect of ceritinib. Ceritinib treatment inhibited RTK/ACK/AR pathway and other downstream pathways in AR+ TNBC cells. The combination of ceritinib and enzalutamide showed a robust inhibitory effect on cell growth of AR+ TNBC cells in vitro and in vivo. Interestingly Ceritinib inhibits FAK-YB-1 signaling pathway that leads to paclitaxel resistance in all types of TNBC cells. The combination of paclitaxel and ceritinib showed drastic inhibition of tumor growth compared to a single drug alone.

CONCLUSIONS

To improve the response of AR antagonist in AR positive TNBC, we designed a novel combinational strategy comprised of enzalutamide and ceritinib to treat AR+ TNBC tumors through the dual blockade of androgen-dependent and androgen-independent AR signaling pathways. Furthermore, we introduced a novel therapeutic combination of ceritinib and paclitaxel for AR negative or AR-low TNBCs and this combination inhibited tumor growth to a great extent. All agents used in our study are FDA-approved, and thus the proposed combination therapy will likely be useful in the clinic.

Role of Nischarin in the pathology of diseases: a special emphasis on breast cancer

Nischarin has been demonstrated to have tumor suppressor functions. In this review, we comprehensively discuss up to date information about Nischarin. In addition, this paper aims to report the prognostic value, clinical relevance, and biological significance of the Nischarin gene (NISCH) in breast cancer (BCa) patients using the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) and The Cancer Genome Atlas (TCGA) datasets. We evaluated NISCH gene expression and its correlation to patient survival, baseline expression, and expression variation based on age groups, tumor stage, tumor size, tumor grade, and lymph node status in different subtypes of BCa. Since NISCH has been extensively reported to inhibit EMT and cancer cell migration, we also checked for the correlation between NISCH and EMT genes in addition to the correlation between NISCH and cell migration genes. Our results indicate that NISCH is a tumor suppressor that plays a critical role in BCa initiation, progression, and tumor development. We find that there is a higher level of NISCH expression in normal breast tissues compared to breast cancer tissues. Also, aggressive subtypes of breast cancers, such as the triple negative/basal category, have decreased levels of NISCH as the disease progresses. Finally, we report that NISCH is inversely correlated with many EMT and cancer cell migration genes in BCa. Interestingly, we identified a significant negative correlation between NISCH expression and its methylation in breast cancer patients. Overall, the goal of this report is to establish a strong clinical basis for further investigation into the cellular, molecular, and physiological roles of NISCH in BCa. Ultimately, NISCH gene expression might be clinically harnessed as a biomarker or predictor of invasiveness and metastasis in BCa.

Nischarin Deletion Reduces Oxidative Metabolism and Overall ATP: A Study Using a Novel NISCHΔ5-6 Knockout Mouse Model

Nischarin (Nisch) is a cytosolic scaffolding protein that harbors tumor-suppressor-like characteristics. Previous studies have shown that Nisch functions as a scaffolding protein and regulates multiple biological activities. In the current study, we prepared a complete Nisch knockout model, for the first time, by deletion of exons 5 and 6. This knockout model was confirmed by Qrt–PCR and Western blotting with products from mouse embryonic fibroblast (MEF) cells. Embryos and adult mice of knockouts are significantly smaller than their wild-type counterparts. Deletion of Nisch enhanced cell migration, as demonstrated by wound type and transwell migration assays. Since the animals were small in size, we investigated Nisch’s effect on metabolism by conducting several assays using the Seahorse analyzer system. These data indicate that Nisch null cells have lower oxygen consumption rates, lower ATP production, and lower levels of proton leak. We examined the expression of 15 genes involved in lipid and fat metabolism, as well as cell growth, and noted a significant increase in expression for many genes in Nischarin null animals. In summary, our results show that Nischarin plays an important physiological role in metabolic homeostasis.

MicroRNA-2355-5p Promotes the Proliferation of Head and Neck Squamous Cell Carcinoma via Suppressing NISCH Expression

Background. MicroRNAs (miRNAs) have emerged as crucial regulators in various cancers. However, the potential role of miR-2355-5p in head and neck squamous cell carcinoma (HNSC) remains unclear. Methods. Bioinformatics methods were implemented to find the candidate target gene of miR-2355-5p. Quantitative real-time PCR was performed to detect RNA expression levels of miR-2355-5p and NISCH, while western blot was carried out for the detection of protein levels of NISCH and cell cycle-related biomarkers. CCK-8, EdU staining, and flow cytometry were employed to measure cell proliferation and cell cycle progression. Dual-luciferase assay and RNA pulldown were conducted to verify the binding relationship between miR-2355-5p and NISCH. Results. The expression levels of miR-2355-5p and NISCH were, respectively, higher and lower in HNSC tissues than those in normal adjacent tissues. The transfection of the miR-2355-5p inhibitor suppressed cell proliferation by arresting the cells at the G1/S transition. The results of luciferase activity and RNA pulldown assays indicated that miR-2355-5p directly targeted the NISCH 3′-untranslated region. Furthermore, the effects of miR-2355-5p inhibition on cell proliferation were reversed after treatment with siRNA against NISCH. Conclusion. In summary, our findings indicate that miR-2355-5p promotes cell cycle progression in HNSC by targeting NISCH. Hence, targeting miR-2355-5p could be a promising therapeutic strategy for the treatment of HNSC

Identification of Phytochemical-Based β-Catenin Nuclear Localization Inhibitor in NSCLC: Differential Targeting Population from Member of Isothiocyanates

Decades of research has convinced us that phytochemical compounds contained within the plant products are the real deal, and they provide benefits such as health maintenance an d cure to illnesses. One of the deadliest noncommunicable diseases today is lung cancer, hence its disease management still deserves attention. Wnt/β-catenin pathway activation conferring cancer stem cell (CSC) activities to non-small cell lung carcinomas (NSCLCs) may explain why the disease is still difficult to cure. In the present study, we assessed several representatives of phytochemical categories consisting of alkaloids, chalcones and isothiocyanates for their inhibitory activity to nuclear localization of β-catenin—an important event for Wnt/β-catenin pathway activation, in lung cancer cell lines. Real-time cell analyzer confirmed that evodiamine (EVO), chelidonine (CHE), isoliquiritigenin (ISO), licochalcone-A (LICO), benzyl isothiocyanate (BI) and phenethylisothiocyanate (PI) exhibited anti-proliferative activities and cytotoxicities to adenocarcinoma cell line SK-LU-1 and human lung CSC primary cell line (HLCSC). Immunofluorescence assay identified that CHE, ISO, LICO, BI and PI were capable of reducing the number of cells harboring β-catenin within the nuclei of these cells. We extended the characterizations of BI and PI in Wnt-dependent squamous cell carcinoma cell line NCI-H1703 on several CSC functions and found that BI was better at inhibiting soft agar colony formation as an output of self-renewal ability, whereas PI was more effective in inhibiting the growth of multicellular tumor spheroid model mimicking micrometastases. Both however were not able to inhibit migration and invasion of NCI-H1703. In conclusion, BI could potentially be used as a safer alternative to target undifferentiated CSCs as adjuvant therapy, whereas PI could be used as chemotherapy to remove bulk tumor.

Understanding the role of integrins in breast cancer invasion, metastasis, angiogenesis, and drug resistance

Integrins are cell adhesion receptors, which are typically transmembrane glycoproteins that connect to the extracellular matrix (ECM). The function of integrins regulated by biochemical events within the cells. Understanding the mechanisms of cell growth by integrins is important in elucidating their effects on tumor progression. One of the major events in integrin signaling is integrin binding to extracellular ligands. Another event is distant signaling that gathers chemical signals from outside of the cell and transmit the signals upon cell adhesion to the inside of the cell. In normal breast tissue, integrins function as checkpoints to monitor effects on cell proliferation, while in cancer tissue these functions altered. The combination of tumor microenvironment and its associated components determines the cell fate. Hypoxia can increase the expression of several integrins. The exosomal integrins promote the growth of metastatic cells. Expression of certain integrins is associated with increased metastasis and decreased prognosis in cancers. In addition, integrin-binding proteins promote invasion and metastasis in breast cancer. Targeting specific integrins and integrin-binding proteins may provide new therapeutic approaches for breast cancer therapies. This review will examine the current knowledge of integrins' role in breast cancer.

Nischarin downregulation attenuates cell injury induced by oxidative stress via Wnt signaling

Nischarin (NISCH) is a key protein functioning as a molecular scaffold and thereby hosting interactions with several protein partners. Here, we aimed to investigate whether NISCH downregulation could protect rat pheochromocytoma (PC12) cells against oxidative stress-induced injury using a model of cell injury induced by hydrogen peroxide (H2O2). Cell viability was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell apoptosis rate was evaluated using flow cytometry. The expressions of apoptosis-related proteins Bax, Bcl-2, caspase-3 and NISCH were examined via Western blot analysis and immunofluorescence staining analyses. The expressions of NISCH, glycogen synthase kinase-3β (GSK-3β) and T-cell factor-1 (TCF-1) were examined using Western blot analysis. The results showed that incubation of H2O2 for 48 h significantly decreased the cell viability, increased the cell apoptosis rate and the NISCH expression in PC12 cells, whereas NISCH downregulation blocked the effects of H2O2 on cells. In addition, the expression of Bcl-2 was significantly reduced, and the expression of Bax and caspase-3 were significantly increased by H2O2 treatment. However, these effects were partially inhibited by the downregulation of NISCH. Furthermore, H2O2 significantly weakened the transduction of Wnt signaling, including the increases of GSK-3β and TCF-1 expressions and the decrease of β-catenin expression, while NISCH downregulation attenuated the effect of H2O2 on Wnt signaling. Moreover, inhibition of the Wnt pathway further decreased the cell viability and promoted the cell apoptosis induced by H2O2 in PC12 cells. Our results suggest that NISCH downregulation may protect cells against oxidative stress-induced injury through regulating the transduction of Wnt signaling.

Impact of Nischarin on EMT regulators in breast cancer cell lines

Nischarin is an integrin-binding protein, which is well known as a novel tumor suppressor. In breast cancer, Nischarin serves a critical role in breast cancer cell migration and invasion. However, the molecular mechanism underlying the role of Nischarin remains unclear. Recent findings have demonstrated that epithelial-mesenchymal transition (EMT) increases the capacity of cell migration and invasion. As a member of the integrin family, it was hypothesized that Nischarin may regulate cellular processes via various signaling pathways associated with the EMT process. The present study detected the mRNA levels of EMT regulators via reverse transcription-quantitative PCR and related protein levels via western blotting in breast cancer cells, following NISCH-overexpression and -knockdown. The results demonstrated that Nischarin inhibits cell proliferation, migration and invasion in breast cancer cells. Furthermore, when the NISCH gene was overexpressed, the relative mRNA level of E-cadherin was increased, while the relative mRNA levels of several transcription factors, such as Snail, ZEB1, N-cadherin, Slug, Twist1 and vimentin, decreased. When NISCH was silenced, these results were reversed. The present results demonstrated that Nischarin suppresses cell migration and invasion via inhibiting the EMT process.

Tizanidine (Hydrochloride) Inhibits A549 Lung Cancer Cell Proliferation and Motility Through Regulating Nischarin

Purpose

Tizanidine hydrochloride (TZN) is a centrally acting α₂-adrenergic agonist. In this study, we aimed to explore the role of TZN on human lung cancer and to elucidate its underlying mechanisms.

Methods

The effect of TZN treatment in A549 cell proliferation, migration, invasion and apoptosis was evaluated by CCK8, transwell and flow cytometer assays. The expression of apoptosis-related proteins and the activation of AKT and Wnt3a/β-catenin pathways were detected by Western blot. From the data of DrugBank, TZN could act as an agonist to target Nischarin in humans. We next investigated the function of Nischarin receptor in lung cancer and its role in the anti-tumor activity of TZN.

Results

The treatment of TZN inhibited the proliferation, migration and invasion of A549 cells, and induced apoptosis. These results were further confirmed by that TZN treatment increased the Bax/Bcl-2 ratio in A549 cells. We also observed that TZN treatment changed the expression and phosphorylation of proteins of AKTand Wnt3a/β-catenin signaling pathway members. By bioinformatics analysis, we found that Nischarin was down-regulated in human lung cancer tissues and patients with high Nischarin expression had a better survival. Moreover, Nischarin functioned as a tumor suppressor in the survival and metastasis of A549 cells through the regulation of AKT and Wnt3a/β-catenin pathways. Knockdown of Nischarin promoted the proliferation, invasion, migration of A549 cells and inhibited the apoptosis, which were reversed by the TZN treatment.

Conclusion

Summary, our data revealed that treatment of TZN inhibited the growth of lung cancer cell line A549 and may be used as a novel strategy for lung cancer therapy.

Chelerythrine Chloride Downregulates β-Catenin and Inhibits Stem Cell Properties of Non-Small Cell Lung Carcinoma

Plant secondary metabolites have been seen as alternatives to seeking new medicines for treating various diseases. Phytochemical scientists remain hopeful that compounds isolated from natural sources could help alleviate the leading problem in oncology—the lung malignancy that kills an estimated two million people annually. In the present study, we characterized a medicinal compound benzophenanthridine alkaloid, called chelerythrine chloride for its anti-tumorigenic activities. Cell viability assays confirmed its cytotoxicity and anti-proliferative activity in non-small cell lung carcinoma (NSCLC) cell lines. Immunofluorescence staining of β-catenin revealed that there was a reduction of nuclear content as well as overall cellular content of β-catenin after treating NCI-H1703 with chelerythrine chloride. In functional characterizations, we observed favorable inhibitory activities of chelerythrine chloride in cancer stem cell (CSC) properties, which include soft agar colony-forming, migration, invasion, and spheroid forming abilities. Interesting observations in chelerythrine chloride treatment noted that its action abides to certain concentration-specific-targeting behavior in modulating β-catenin expression and apoptotic cell death. The downregulation of β-catenin implicates the downregulation of CSC transcription factors like SOX2 and MYC. In conclusion, chelerythrine chloride has the potential to mitigate cancer growth due to inhibitory actions toward the tumorigenic activity of CSC in lung cancer and it can be flexibly adjusted according to concentration to modulate specific targeting in different cell lines.

Knockout model reveals the role of Nischarin in mammary gland development, breast tumorigenesis and response to metformin treatment

Previously, our lab discovered the protein Nischarin and uncovered its role in regulating cell migration and invasion via its interactions with several proteins. We subsequently described a role for Nischarin in breast cancer, in which it is frequently underexpressed. To characterize Nischarin's role in breast tumorigenesis and mammary gland development more completely, we deleted a critical region of the Nisch gene (exons 7-10) from the mouse genome and observed the effects. Mammary glands in mutant animals showed delayed terminal end bud formation but did not develop breast tumors spontaneously. Therefore, we interbred the animals with transgenic mice expressing the mouse mammary tumor virus-polyoma middle T-antigen (MMTV-PyMT) oncogene. The MMTV-PyMT mammary glands lacking Nischarin showed increased hyperplasia compared to wild-type animal tissues. Furthermore, we observed significantly increased tumor growth and metastasis in Nischarin mutant animals. Surprisingly, Nischarin deletion decreased activity of AMPK and subsequently its downstream effectors. Given this finding, we treated these animals with metformin, which enhances AMPK activity. Here, we show for the first time, metformin activates AMPK signaling and inhibits tumor growth of Nischarin lacking PyMT tumors suggesting a potential use for metformin as a cancer therapeutic, particularly in the case of Nischarin-deficient breast cancers.

Integrins: Moonlighting Proteins in Invadosome Formation

Invadopodia are actin-rich protrusions developed by transformed cells in 2D/3D environments that are implicated in extracellular matrix (ECM) remodeling and degradation. These structures have an undoubted association with cancer invasion and metastasis because invadopodium formation in vivo is a key step for intra/extravasation of tumor cells. Invadopodia are closely related to other actin-rich structures known as podosomes, which are typical structures of normal cells necessary for different physiological processes during development and organogenesis. Invadopodia and podosomes are included in the general term 'invadosomes,' as they both appear as actin puncta on plasma membranes next to extracellular matrix metalloproteinases, although organization, regulation, and function are slightly different. Integrins are transmembrane proteins implicated in cell-cell and cell-matrix interactions and other important processes such as molecular signaling, mechano-transduction, and cell functions, e.g., adhesion, migration, or invasion. It is noteworthy that integrin expression is altered in many tumors, and other pathologies such as cardiovascular or immune dysfunctions. Over the last few years, growing evidence has suggested a role of integrins in the formation of invadopodia. However, their implication in invadopodia formation and adhesion to the ECM is still not well known. This review focuses on the role of integrins in invadopodium formation and provides a general overview of the involvement of these proteins in the mechanisms of metastasis, taking into account classic research through to the latest and most advanced work in the field.

Exosomes from Nischarin-Expressing Cells Reduce Breast Cancer Cell Motility and Tumor Growth

Exosomes are small extracellular microvesicles that are secreted by cells when intracellular multivesicular bodies fuse with the plasma membrane. We have previously demonstrated that Nischarin inhibits focal adhesion formation, cell migration, and invasion, leading to reduced activation of focal adhesion kinase. In this study, we propose that the tumor suppressor Nischarin regulates the release of exosomes. When cocultured on exosomes from Nischarin-positive cells, breast cancer cells exhibited reduced survival, migration, adhesion, and spreading. The same cocultures formed xenograft tumors of significantly reduced volume following injection into mice. Exosomes secreted by Nischarin-expressing tumors inhibited tumor growth. Expression of only one allele of Nischarin increased secretion of exosomes, and Rab14 activity modulated exosome secretions and cell growth. Taken together, this study reveals a novel role for Nischarin in preventing cancer cell motility, which contributes to our understanding of exosome biology. SIGNIFICANCE: Regulation of Nischarin-mediated exosome secretion by Rab14 seems to play an important role in controlling tumor growth and migration.See related commentary by McAndrews and Kalluri, p. 2099.

Suppression of PDHX by microRNA-27b deregulates cell metabolism and promotes growth in breast cancer

BACKGROUND

The disruption of normal gene regulation due to microRNA dysfunction is a common event in cancer pathogenesis. MicroRNA-27b is an example of an oncogenic miRNA, and it is frequently upregulated in breast cancer. MicroRNAs have been found to deregulate tumor metabolism, which typically manifests as heightened cellular glucose uptake in consort with increased flux through glycolysis, followed by the preferential conversion of glycolytic pyruvate into lactate (a phenomenon known as the Warburg Effect). Pyruvate Dehydrogenase, an enzyme complex linking glycolysis with downstream oxidative metabolism, represents a key location where regulation of metabolism occurs; PDHX is a key structural component of this complex and is essential for its function.

METHODS

We sought to characterize the role of miR-27b in breast cancer by identifying novel transcripts under its control. We began by utilizing luciferase, RNA, and protein assays to establish PDHX as a novel target of miR-27b. We then tested whether miR-27b could alter metabolism using several metabolite assay kits and performed a seahorse analysis. We also examined how the altered metabolism might affect cell proliferation. Lastly, we confirmed the relevance of our findings in human breast tumor samples.

RESULTS

Our data indicate that Pyruvate Dehydrogenase Protein X is a credible target of miR-27b in breast cancer. Mechanistically, by suppressing PDHX, miR-27b altered levels of pyruvate, lactate and citrate, as well as reducing mitochondrial oxidation and promoting extracellular acidification. These changes corresponded with an increased capacity for cell proliferation. In human breast tumor samples, PDHX expression was deficient, and low levels of PDHX were associated with reduced patient survival.

CONCLUSIONS

MicroRNA-27b targets PDHX, resulting in an altered metabolic configuration that is better suited to fuel biosynthetic processes and cell proliferation, thereby promoting breast cancer progression.

Expression of long noncoding RNA MALAT1 correlates with increased levels of Nischarin and inhibits oncogenic cell functions in breast cancer

Malat1 is a long noncoding RNA with a wide array of functions, including roles in regulating cancer cell migration and metastasis. However, the nature of its involvement in control of these oncogenic processes is incompletely understood. In the present study, we investigate the role of Malat1 and the effects of Malat1 KO in a breast cancer cell model. Our selection of Malat1 as the subject of inquiry followed initial screening experiments seeking to identify lncRNAs which are altered in the presence or absence of Nischarin, a gene of interest previously discovered by our lab. Nischarin is a well characterized tumor suppressor protein and actively represses cell proliferation, migration, and invasion in breast cancer. Our microarray screen for lncRNAs revealed multiple lncRNAs to be significantly elevated in cells ectopically expressing Nischarin compared to control cancer cells, which have only marginal Nisch expression. Using these cells, we assess how the link between Nischarin and Malat1 affects cancer cell function, finding that Malat1 confers an inhibitory effect on cell growth and migration which is lost following Malat1 KO, but in a Nisch-dependent context. Specifically, Malat1 KO in the background of low Nischarin expression had a limited effect on cell functions, while Malat1 KO in cells with high levels of Nischarin led to significant increases in cell proliferation and migration. In summary, this project provides further clarity concerning the function of Malat1, specifically in breast cancer, while also indicating that the Nischarin expression context is an important factor in the determining how Malat1 activity is governed in breast cancer.

Nischarin regulates focal adhesion and Invadopodia formation in breast cancer cells

Background

During metastasis, tumor cells move through the tracks of extracellular matrix (ECM). Focal adhesions (FAs) are the protein complexes that link the cell cytoskeleton to the ECM and their presence is necessary for cell attachment. The tumor suppressor Nischarin interacts with a number of signaling proteins such as Integrin α5, PAK1, LIMK1, LKB1, and Rac1 to prevent cancer cell migration. Although previous findings have shown that Nischarin exerts this migratory inhibition by interacting with other proteins, the effects of these interactions on the entire FA machinery are unknown.

Methods

RT-PCR, Western Blotting, invadopodia assays, and immunofluorescence were used to examine FA gene expression and determine whether Nischarin affects cell attachment, as well as the proteins that regulate it.

Results

Our data show that Nischarin prevents cell migration and invasion by altering the expression of key focal adhesion proteins. Furthermore, we have found that Nischarin-expressing cells have reduced ability to attach the ECM, which in turn leads to a decrease in invadopodia-mediated matrix degradation.

Conclusions

These experiments demonstrate an important role of Nischarin in regulating cell attachment, which adds to our understanding of the early events of the metastatic process in breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0764-6) contains supplementary material, which is available to authorized users.

Suppression of Adaptive Responses to Targeted Cancer Therapy by Transcriptional Repression

Acquired drug resistance is a major factor limiting the effectiveness of targeted cancer therapies. Targeting tumors with kinase inhibitors induces complex adaptive programs that promote the persistence of a fraction of the original cell population, facilitating the eventual outgrowth of inhibitor-resistant tumor clones. We show that the addition of a newly identified CDK7/12 inhibitor, THZ1, to targeted therapy enhances cell killing and impedes the emergence of drug-resistant cell populations in diverse cellular and in vivo cancer models. We propose that targeted therapy induces a state of transcriptional dependency in a subpopulation of cells poised to become drug tolerant, which THZ1 can exploit by blocking dynamic transcriptional responses, promoting remodeling of enhancers and key signaling outputs required for tumor cell survival in the setting of targeted therapy. These findings suggest that the addition of THZ1 to targeted therapies is a promising broad-based strategy to hinder the emergence of drug-resistant cancer cell populations.Significance: CDK7/12 inhibition prevents active enhancer formation at genes, promoting resistance emergence in response to targeted therapy, and impedes the engagement of transcriptional programs required for tumor cell survival. CDK7/12 inhibition in combination with targeted cancer therapies may serve as a therapeutic paradigm for enhancing the effectiveness of targeted therapies. Cancer Discov; 8(1); 59-73. ©2017 AACR.See related commentary by Carugo and Draetta, p. 17This article is highlighted in the In This Issue feature, p. 1.

Nischarin inhibition alters energy metabolism by activating AMP-activated protein kinase

Nischarin (Nisch) is a key protein functioning as a molecular scaffold and thereby hosting interactions with several protein partners. To explore the physiological importance of Nisch, here we generated Nisch loss-of-function mutant mice and analyzed their metabolic phenotype. Nisch-mutant embryos exhibited delayed development, characterized by small size and attenuated weight gain. We uncovered the reason for this phenotype by showing that Nisch binds to and inhibits the activity of AMP-activated protein kinase (AMPK), which regulates energy homeostasis by suppressing anabolic and activating catabolic processes. The Nisch mutations enhanced AMPK activation and inhibited mechanistic target of rapamycin signaling in mouse embryonic fibroblasts as well as in muscle and liver tissues of mutant mice. Nisch-mutant mice also exhibited increased rates of glucose oxidation with increased energy expenditure, despite reduced overall food intake. Moreover, the Nisch-mutant mice had reduced expression of liver markers of gluconeogenesis associated with increased glucose tolerance. As a result, these mice displayed decreased growth and body weight. Taken together, our results indicate that Nisch is an important AMPK inhibitor and a critical regulator of energy homeostasis, including lipid and glucose metabolism.

A mutation in Nischarin causes otitis media via LIMK1 and NF-κB pathways

Otitis media (OM), inflammation of the middle ear (ME), is a common cause of conductive hearing impairment. Despite the importance of the disease, the aetiology of chronic and recurrent forms of middle ear inflammatory disease remains poorly understood. Studies of the human population suggest that there is a significant genetic component predisposing to the development of chronic OM, although the underlying genes are largely unknown. Using N-ethyl-N-nitrosourea mutagenesis we identified a recessive mouse mutant, edison, that spontaneously develops a conductive hearing loss due to chronic OM. The causal mutation was identified as a missense change, L972P, in the Nischarin (NISCH) gene. edison mice develop a serous or granulocytic effusion, increasingly macrophage and neutrophil rich with age, along with a thickened, inflamed mucoperiosteum. We also identified a second hypomorphic allele, V33A, with only modest increases in auditory thresholds and reduced incidence of OM. NISCH interacts with several proteins, including ITGA5 that is thought to have a role in modulating VEGF-induced angiogenesis and vascularization. We identified a significant genetic interaction between Nisch and Itga5; mice heterozygous for Itga5-null and homozygous for edison mutations display a significantly increased penetrance and severity of chronic OM. In order to understand the pathological mechanisms underlying the OM phenotype, we studied interacting partners to NISCH along with downstream signalling molecules in the middle ear epithelia of edison mouse. Our analysis implicates PAK1 and RAC1, and downstream signalling in LIMK1 and NF-κB pathways in the development of chronic OM.

Otitis media (OM) is the most common cause of deafness in children and is primarily characterised by inflammation of the middle ear. It is the most common cause of surgery in children in the developed world, with many children developing recurrent and chronic forms of OM undergoing tympanostomy tube insertion. There is evidence that a significant genetic component contributes towards the development of recurrent and chronic forms of OM. The mouse has been a powerful tool for identifying the genes involved in chronic OM. In this study we identified and characterised edison, a novel mouse model of chronic OM that shares important features with the chronic disease in humans. A mutation in the Nisch gene causes edison mice to spontaneously develop OM following birth and subsequently develop chronic OM, with an associated hearing loss. Our molecular analysis of the mutation reveals the underlying pathological mechanisms and pathways involved in OM in the edison mouse, involving PAK1, RAC1 and downstream signalling in LIMK1 and NF-κB pathways. Identification of the edison mutant provides an important genetic disease model of chronic OM and implicates a new gene and genetic pathways involved in predisposition to OM.

Connecting myelin-related and synaptic dysfunction in schizophrenia with SNP-rich gene expression hubs

Combining genome-wide mapping of SNP-rich regions in schizophrenics and gene expression data in all brain compartments across the human life span revealed that genes with promoters most frequently mutated in schizophrenia are expression hubs interacting with far more genes than the rest of the genome. We summed up the differentially methylated “expression neighbors” of genes that fall into one of 108 distinct schizophrenia-associated loci with high number of SNPs. Surprisingly, the number of expression neighbors of the genes in these loci were 35 times higher for the positively correlating genes (32 times higher for the negatively correlating ones) than for the rest of the ~16000 genes. While the genes in the 108 loci have little known impact in schizophrenia, we identified many more known schizophrenia-related important genes with a high degree of connectedness (e.g. MOBP, SYNGR1 and DGCR6), validating our approach. Both the most connected positive and negative hubs affected synapse-related genes the most, supporting the synaptic origin of schizophrenia. At least half of the top genes in both the correlating and anti-correlating categories are cancer-related, including oncogenes (RRAS and ALDOA), providing further insight into the observed inverse relationship between the two diseases.

Expression of Nischarin negatively correlates with estrogen receptor and alters apoptosis, migration and invasion in human breast cancer

Nischarin, a novel integrin binding protein, has been demonstrated its negative effects on cell migration and invasion. However, the biological role of Nischarin in breast cancer has not been fully elucidated yet. Our study aimed to analyze the association between Nischarin expression and clinical features of breast cancer patients, and further investigate the role of Nischarin in breast cancer cells apoptosis, migration and invasion. Results showed that Nischarin expression was significantly lower in breast cancer tissues (37.8%, 23/67) than in normal tissues (61.8%, 21/34; P < 0.05), and the expression of Nischarin significantly negatively correlated with estrogen receptor status. Similarly, Nischarin expression was highest in normal breast cell line HBL-100 while triple-negative breast cancer cell line MDA-MB-231 had the lowest expression of Nischarin. Further experiments demonstrated that overexpression of Nischarin may induce apoptosis, and inhibit cell migration and invasion. The present data confirmed that Nishcharin might be a novel tumor suppressor and plays an important role in breast cancer cell apoptosis and metastasis, which can be used as a potential therapeutic target for breast cancer treatment.

A combined ligand- and structure-based approach for the identification of rilmenidine-derived compounds which synergize the antitumor effects of doxorubicin

The clonidine-like central antihypertensive agent rilmenidine, which has high affinity for I1-type imidazoline receptors (I1-IR) was recently found to have cytotoxic effects on cultured cancer cell lines. However, due to its pharmacological effects resulting also from α2-adrenoceptor activation, rilmenidine cannot be considered a suitable anticancer drug candidate. Here, we report the identification of novel rilmenidine-derived compounds with anticancer potential and devoid of α2-adrenoceptor effects by means of ligand- and structure-based drug design approaches. Starting from a large virtual library, eleven compounds were selected, synthesized and submitted to biological evaluation. The most active compound 5 exhibited a cytotoxic profile similar to that of rilmenidine, but without appreciable affinity to α2-adrenoceptors. In addition, compound 5 significantly enhanced the apoptotic response to doxorubicin, and may thus represent an important tool for the development of better adjuvant chemotherapeutic strategies for doxorubicin-insensitive cancers.

Inhibition of Nischarin Expression Promotes Neurite Outgrowth through Regulation of PAK Activity

Nischarin is a cytoplasmic protein expressed in various organs that plays an inhibitory role in cell migration and invasion and the carcinogenesis of breast cancer cells. We previously reported that Nischarin is highly expressed in neuronal cell lines and is differentially expressed in the brain tissue of adult rats. However, the physiological function of Nischarin in neural cells remains unknown. Here, we show that Nischarin is expressed in rat primary cortical neurons but not in astrocytes. Nischarin is localized around the nucleus and dendrites. Using shRNA to knockdown the expression of endogenous Nischarin significantly increases the percentage of neurite-bearing cells, remarkably increases neurite length, and accelerates neurite extension in neuronal cells. Silencing Nischarin expression also promotes dendrite elongation in rat cortical neurons where Nischarin interacts with p21-activated kinase 1/2 (PAK1/2) and negatively regulates phosphorylation of both PAK1 and PAK2. The stimulation of neurite growth observed in cells with decreased levels of Nischarin is partially abolished by IPA3-mediated inhibition of PAK1 activity. Our findings indicate that endogenous Nischarin inhibits neurite outgrowth by blocking PAK1 activation in neurons.

Rho Kinase (ROCK) Inhibitors and Their Therapeutic Potential

Rho kinases (ROCKs) belong to the serine-threonine family, the inhibition of which affects the function of many downstream substrates. As such, ROCK inhibitors have potential therapeutic applicability in a wide variety of pathological conditions including asthma, cancer, erectile dysfunction, glaucoma, insulin resistance, kidney failure, neuronal degeneration, and osteoporosis. To date, two ROCK inhibitors have been approved for clinical use in Japan (fasudil and ripasudil) and one in China (fasudil). In 1995 fasudil was approved for the treatment of cerebral vasospasm, and more recently, ripasudil was approved for the treatment of glaucoma in 2014. In this Perspective, we present a comprehensive review of the physiological and biological functions for ROCK, the properties and development of over 170 ROCK inhibitors as well as their therapeutic potential, the current status, and future considerations.

Breast Cancer Tumor Suppressors: A Special Emphasis on Novel Protein Nischarin

Tumor suppressor genes regulate cell growth and prevent spontaneous proliferation that could lead to aberrant tissue function. Deletions and mutations of these genes typically lead to progression through the cell-cycle checkpoints, as well as increased cell migration. Studies of these proteins are important as they may provide potential treatments for breast cancers. In this review, we discuss a comprehensive overview on Nischarin, a novel protein discovered by our laboratory. Nischarin, or imidazoline receptor antisera-selected protein, is a protein involved in a vast number of cellular processes, including neuronal protection and hypotension. The NISCH promoter experiences hypermethylation in several cancers, whereas some highly aggressive breast cancer cells exhibit genomic loss of the NISCH locus. Furthermore, we discuss data illustrating a novel role of Nischarin as a tumor suppressor in breast cancer. Analysis of this new paradigm may shed light on various clinical questions. Finally, the therapeutic potential of Nischarin is discussed.

Manipulating Cx43 expression triggers gene reprogramming events in dermal fibroblasts from oculodentodigital dysplasia patients

Oculodentodigital dysplasia (ODDD) is primarily an autosomal dominant disorder linked to over 70 GJA1 gene [connexin43 (Cx43)] mutations. For nearly a decade, our laboratory has been investigating the relationship between Cx43 and ODDD by expressing disease-linked mutants in reference cells, tissue-relevant cell lines, 3D organ cultures and by using genetically modified mouse models of human disease. Although salient features of Cx43 mutants have been revealed, these models do not necessarily reflect the complexity of the human context. To further overcome these limitations, we have acquired dermal fibroblasts from two ODDD-affected individuals harbouring D3N and V216L mutations in Cx43, along with familial controls. Using these ODDD patient dermal fibroblasts, which naturally produce less GJA1 gene product, along with RNAi and RNA activation (RNAa) approaches, we show that manipulating Cx43 expression triggers cellular gene reprogramming. Quantitative RT-PCR, Western blot and immunofluorescent analysis of ODDD patient fibroblasts show unusually high levels of extracellular matrix (ECM)-interacting proteins, including integrin α5β1, matrix metalloproteinases as well as secreted ECM proteins collagen-I and laminin. Cx43 knockdown in familial control cells produces similar effects on ECM expression, whereas Cx43 transcriptional up-regulation using RNAa decreases production of collagen-I. Interestingly, the enhanced levels of ECM-associated proteins in ODDD V216L fibroblasts is not only a consequence of increased ECM gene expression, but also due to an apparent deficit in collagen-I secretion which may further contribute to impaired collagen gel contraction in ODDD fibroblasts. These findings further illuminate the altered function of Cx43 in ODDD-affected individuals and highlight the impact of manipulating Cx43 expression in human cells.

Frequent Loss of NISCH Promotes Tumor Proliferation and Invasion in Ovarian Cancer via Inhibiting the FAK Signal Pathway

NISCH encodes the imidazoline receptor Nischarin and is a known tumor suppressor in many human malignancies; however, its roles in ovarian cancer are still largely unknown. Here, we aim to investigate the biologic functions of NISCH in ovarian cancer. We found that NISCH was significantly downregulated, which correlated considerably with advanced tumor stage, poor differentiation, lymph node metastasis, and the serous/mucinous subtypes in a panel of ovarian cancer tissues. Moreover, NISCH gene silencing was mainly the product of promoter hypermethylation, which could be reversed by treatment with 5-aza-dC. In vitro, NISCH overexpression suppressed cell proliferation and colony formation by hindering cell-cycle progression, whereas the opposite was observed in NISCH knockdown counterparts. In vivo, abundant NISCH expression hindered the growth of HO8910 xenografts, whereas NISCH knockdown accelerated the growth of SKOV3 xenografts. In addition, NISCH significantly attenuated cell invasion by inhibiting the phosphorylation of FAK and ERK, which could be neutralized by PF-562271 (a FAK/Pyk2 inhibitor). Accordingly, NISCH knockdown xenografts exhibited increased peritoneal/pelvic metastases that were not present in counterparts treated with PF-562271. Furthermore, NISCH expression in primary ovarian cancer cells predicted a cellular resistance to PF-562271. In conclusion, we showed that NISCH was frequently silenced by promoter hypermethylation in human ovarian cancer. NISCH manipulated cellular proliferation and invasion by arresting cell cycle and inhibiting the FAK signal. Our findings revealed the biologic functions of NISCH in ovarian cancer, and might be useful for treating patients with aberrant expression of NISCH.

Expression of integrin-binding protein Nischarin in metastatic breast cancer

The present study aimed to investigate the expression of Nischarin protein in primary breast cancer (PBC), and to evaluate its role in tumor metastasis. Paired specimens of breast cancer tissues and adjacent normal tissues were surgically obtained from 60 patients with PBC at the Zhejiang Cancer Hospital (Hangzhou, China). Nischarin protein concentrations were determined by an ELISA assay. Breast cancer tissues exhibited a significantly lower concentration of Nischarin (5.86±3.19 ng/ml) compared with that of the adjacent noncancerous tissues (9.25±3.65 ng/ml; P<0.001). Furthermore, cancer tissue from patients with lymph node metastasis had significantly lower levels of Nischarin protein (4.69±2.40 ng/ml) than those of patients without lymph node metastasis (7.04±3.47 ng/ml; P=0.004). There was no significant difference in Nischarin protein expression levels between patients with grade I, II or III PBC (grade I, 5.44±3.57 ng/ml; grade II, 6.42±3.85 ng/ml and grade III, 5.10±1.18 ng/ml; P=0.765). The significant differences in the expression of Nischarin between: i) Cancer tissue and noncancerous tissue and ii) patients with and without lymph node metastasis, suggested that Nischarin may have a significant role in tumor occurrence and metastasis of breast cancer. Nischarin expression may therefore be used as a marker to predict the invasiveness and metastasis of PBC.

A novel phosphatidylinositol 3-kinase (PI3K) inhibitor directs a potent FOXO-dependent, p53-independent cell cycle arrest phenotype characterized by the differential induction of a subset of FOXO-regulated genes

Introduction

The activation of the phosphoinositide 3-kinase (PI3K)/AKT signalling pathway is one the most frequent genetic events in breast cancer, consequently the development of PI3K inhibitors has attracted much attention. Here we evaluate the effect of PI3K inhibition on global gene expression in breast cancer cells.

Methods

We used a range of methodologies that include in silico compound analysis, in vitro kinase assays, cell invasion assays, proliferation assays, genome-wide transcription studies (Agilent Technologies full genome arrays), gene set enrichment analysis, quantitative real-time PCR, immunoblotting in addition to chromatin immunoprecipitation.

Results

We defined the physico-chemical and the biological properties of ETP-45658, a novel potent PI3K inhibitor. We demonstrated that ETP-45658 potently inhibited cell proliferation within a broad range of human cancer cells, most potently suppressing the growth of breast cancer cells via inhibiting cell cycle. We show that this response is Forkhead box O (FOXO) protein dependent and p53 independent. Our genome-wide microarray analysis revealed that the cell cycle was the most affected biological process after exposure to ETP-45658 (or our control PI3K inhibitor PI-103), that despite the multiple transcription factors that are regulated by the PI3K/AKT signalling cascade, only the binding sites for FOXO transcription factors were significantly enriched and only a subset of all FOXO-dependent genes were induced. This disparity in gene transcription was not due to differential FOXO promoter recruitment.

Conclusions

The constitutive activation of PI3Ks and thus the exclusion of FOXO transcription factors from the nucleus is a key feature of breast cancer. Our results presented here highlight that PI3K inhibition activates specific FOXO-dependent genes that mediate cell cycle arrest in breast cancer cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0482-y) contains supplementary material, which is available to authorized users.

Role of the focal adhesion protein TRIM15 in colon cancer development

The tripartite motif containing (TRIM) proteins are a large family of proteins that have been implicated in many biological processes including cell differentiation, apoptosis, transcriptional regulation, and signaling pathways. Here, we show that TRIM15 co-localized to focal adhesions through homo-dimerization and significantly suppressed cell migration. Domain mapping analysis indicated that B-box2 and PRY domains were essential for TRIM15 localization to focal adhesions and inhibition of cell migration. Our protein-protein interaction screen of TRIM15 with the integrin adhesome identified several TRIM15 interacting proteins including coronin 1B, cortactin, filamin binding LIM protein1, and vasodilator-stimulated phosphoprotein, which are involved in actin cytoskeleton dynamics. TRIM15 expression was tissue-restricted and downregulated in colon cancer. Level of TRIM15 expression was associated with colon cancer cell migration, as well as both in vitro and in vivo tumor growth. These data provide novel insights into the role of TRIM15 as an additional component of the integrin adhesome, regulating cell migration, and suggest that TRIM15 may function as a tumor suppressor of colon cancer.

Meta-analysis of the differentially expressed breast cancer-related microRNA expression profiles

MicroRNAs (miRNAs), as non-coding RNA molecules, play an important role in regulating gene expression in cancer development. Meta-analysis was used to screen overlapping differentially expressed miRNAs (DEmiRNAs) in three studies. The miRanda was used to identify target genes related to overlapping DEmiRNAs. These Gene Ontology (GO) and Encyclopaedia of Genes and Genomes (KEGG) database were applied to further predict the function of these target genes. As a result, we obtained seven overlapping miRNAs and six significantly over-represented GO terms closely related to breast cancer. After KEGG pathways analysis, a total of seven key target genes were involved in the Wnt signalling pathway (p = 0.0002). Our findings from this study suggest that the altered levels of miRNAs might have great potential to serve as novel, non-invasive biomarkers for early detection of breast cancer.

How integrins control breast biology

This article explores new ideas about how the ECM-integrin axis controls normal and malignant breast biology. We discuss the role of integrins in mammary stem cells, and how cell-matrix interactions regulate ductal and alveolar development and function. We also examine the contribution of integrins to tissue disorganisation and metastasis, and how an altered stromal and ECM tumour microenvironment affects the cancer cell niche both within primary tumours and at distant sites. Finally, we mention novel strategies for integrin-directed breast cancer treatment.

Integrin-binding protein nischarin interacts with tumor suppressor liver kinase B1 (LKB1) to regulate cell migration of breast epithelial cells

Biallelic inactivation of LKB1, a serine/threonine kinase, has been detected in 30% of lung adenocarcinomas, and inhibition of breast tumor growth has been demonstrated. We have identified the tumor suppressor, Nischarin, as a novel binding partner of LKB1. Our mapping analysis shows that the N terminus of Nischarin interacts with amino acids 44-436 of LKB1. Time lapse microscopy and Transwell migration data show that the absence of both Nischarin and LKB1 from an invasive breast cancer cell line (MDA-MB-231) enhances migration as measured by increased distance and speed of migrating cells. Our data suggest that this is a result of elevated PAK1 and LIMK1 phosphorylation. Moreover, the absence of Nischarin and LKB1 increased tumor growth in vivo. Consistent with this, the percentage of S phase cells was increased, as demonstrated by flow cytometry and enhanced cyclin D1. The absence of Nischarin and LKB1 also led to a dramatic increase in the formation of lung metastases. Our studies, for the first time, demonstrate functional interaction between LKB1 and Nischarin to inhibit cell migration and breast tumor progression. Mechanistically, we show that these two proteins together regulate PAK-LIMK-Cofilin and cyclin D1/CDK4 pathways.

Cigarette smoke induces methylation of the tumor suppressor gene NISCH

We have previously identified a putative tumor suppressor gene, NISCH, whose promoter is methylated in lung tumor tissue as well as in plasma obtained from lung cancer patients. NISCH was observed to be more frequently methylated in smoker lung cancer patients than in non-smoker lung cancer patients. Here, we investigated the effect of tobacco smoke exposure on methylation of the NISCH gene. We tested methylation of NISCH after oral keratinocytes were exposed to mainstream and side stream cigarette smoke extract in culture. Methylation of the promoter region of the NISCH gene was also evaluated in plasma obtained from lifetime non-smokers and light smokers (<20 pack/year), with and without lung tumors, and heavy smokers (20+ pack/year) without disease. Promoter methylation of NISCH was tested by quantitative fluorogenic real-time PCR in all samples. Promoter methylation of NISCH occurred after exposure to mainstream tobacco smoke as well as to side stream tobacco smoke in normal oral keratinocyte cell lines. NISCH methylation was also detected in 68% of high-risk, heavy smokers without detectable tumors. Interestingly, in light smokers, NISCH methylation was present in 69% of patients with lung cancer and absent in those without disease. Our pilot study indicates that tobacco smoke induces methylation changes in the NISCH gene promoter before any detectable cancer. Methylation of the NISCH gene was also found in lung cancer patients' plasma samples. After confirming these findings in longitudinally collected plasma samples from high-risk populations (such as heavy smokers), examining patients for hypermethylation of the NISCH gene may aid in identifying those who should undergo additional screening for lung cancer.

Prooncogenic factors miR-23b and miR-27b are regulated by Her2/Neu, EGF, and TNF-α in breast cancer

miRNAs (miR) are a critical class of small (21-25 nucleotides) noncoding endogenous RNAs implicated in gene expression regulation. We identified miR-23b and miR-27b as miRNAs that are highly upregulated in human breast cancer. We found that engineered knockdown of miR-23b and miR-27b substantially repressed breast cancer growth. Nischarin (NISCH) expression was augmented by knockdown of miR-23b as well as miR-27b. Notably, these miRNAs and Nischarin were inversely expressed in human breast cancers, underscoring their biologic relevance. We showed the clinical relevance of the expression of these miRNAs and showed that high expression of miR-23b and miR-27b correlates with poor outcome in breast cancer. Moreover, intraperitoneally delivered anti-miR-27b restored Nischarin expression and decreased tumor burden in a mouse xenograft model of human mammary tumor. Also, we report for the first time that HER2/neu (ERBB2), EGF, and TNF-α promote miR-23b/27b expression through the AKT/NF-κB signaling cascade. Nischarin was found to regulate miR-27b/23b expression through a feedback loop mechanism by suppressing NF-κB phosphorylation. Because anti-miR-27b compounds that suppress miR-27b inhibit tumor growth, the anti-miR-27b seems to be a good candidate for the development of new antitumor therapies.

Nischarin is differentially expressed in rat brain and regulates neuronal migration

Nischarin is a protein known to inhibit breast cancer cell motility by regulating the signaling of the Rho GTPase family. However, little is known about its location and function in the nervous system. The aim of the present study was to investigate the regional and cellular expression and functions of Nischarin in the adult rodent brain. As assessed by real-time PCR, Western blot analysis and immunostaining, we found that Nischarin was widely distributed throughout the brain, with a higher expression in the cerebral cortex and hippocampus. Double-labeling showed that Nischarin was expressed in neurons and was mainly located in the perinuclear region and F-actin-rich protrusions. The expression pattern of Nischarin in the brain was thought to be closely associated with its function. This was verified by our findings from cell migration assays that Nischarin regulated neuronal migration. These results provide a preliminary survey of the distribution of Nischarin in different regions and cell types in the rat brain. This might help to elucidate its physiological roles, and to evaluate its potential clinical implications.

Integrin α5β1, the Fibronectin Receptor, as a Pertinent Therapeutic Target in Solid Tumors

Integrins are transmembrane heterodimeric proteins sensing the cell microenvironment and modulating numerous signalling pathways. Changes in integrin expression between normal and tumoral cells support involvement of specific integrins in tumor progression and aggressiveness. This review highlights the current knowledge about α5β1 integrin, also called the fibronectin receptor, in solid tumors. We summarize data showing that α5β1 integrin is a pertinent therapeutic target expressed by tumoral neovessels and tumoral cells. Although mainly evaluated in preclinical models, α5β1 integrin merits interest in particular in colon, breast, ovarian, lung and brain tumors where its overexpression is associated with a poor prognosis for patients. Specific α5β1 integrin antagonists will be listed that may represent new potential therapeutic agents to fight defined subpopulations of particularly aggressive tumors.