Inhibition of epithelial to mesenchymal transition in metastatic breast carcinoma cells by c-Src suppression

The Role of Epithelial-Mesenchymal Transition in Osteosarcoma Progression: From Biology to Therapy

Osteosarcoma (OS) is the most common primary malignant bone tumor, predominantly affecting children, adolescents, and young adults. Epithelial-mesenchymal transition (EMT), a process in which epithelial cells lose their cell-cell adhesion and gain migratory and invasive properties, has been extensively studied in various carcinomas. However, its role in mesenchymal tumors like osteosarcoma remains less explored. EMT is increasingly recognized as a key factor in the progression of osteosarcoma, contributing to tumor invasion, metastasis, and resistance to chemotherapy. This narrative review aims to provide a comprehensive overview of the molecular mechanisms driving EMT in osteosarcoma, highlighting the involvement of signaling pathways such as TGF-β, transcription factors like Snail, Twist, and Zeb, and the role of microRNAs in modulating EMT. Furthermore, we discuss how EMT correlates with poor prognosis and therapy resistance in osteosarcoma patients, emphasizing the potential of targeting EMT for therapeutic intervention. Recent advancements in understanding EMT in osteosarcoma have opened new avenues for treatment, including EMT inhibitors and combination therapies aimed at overcoming drug resistance. By integrating biological insights with clinical implications, this review underscores the importance of EMT as a critical process in osteosarcoma progression and its potential as a therapeutic target.

A meta‑analysis assessing the cytotoxicity of nanoparticles on MCF7 breast cancer cells

The present study summarizes the current available literature regarding the viability of MCF7 breast cancer cells treated with gold (Au), silver (Ag) or zinc oxide (ZnO) nanoparticles at varying doses for 48 h. The data for this study were obtained from diverse research articles published between 2013 and 2023 using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. The evaluation focused on 20 PRISMA-compliant articles concerning MCF7 cells, yielding 137 outcome measures for meta-analysis. A generalized linear mixed model meta-analysis approach was employed to glean insights into the effects of novel nanoparticles on MCF7 breast cancer cells. The analysis covered a wide range of concentrations: Ag nanoparticles from 1.25 to 1,000 µg/ml, Au nanoparticles from 50 to 150 µg/ml, and ZnO nanoparticles from 1 to 1,000 µg/ml. Both intra-nanoparticle and inter-nanoparticle comparisons were conducted to detect differences. The findings showed that when concentrations reached or exceeded 60 µg/ml, considerable variation of cell viability was observed: Treatment with Ag nanoparticles resulted in cell viability ranging from 9 to 45%, ZnO nanoparticles resulted in cell viability ranging from 20 to 40%, and Au nanoparticles resulted in cell viability ranging from 3 to 58%. These findings indicated the significance of thoroughly exploring nanoparticle dosage to acquire a comprehensive understanding of their influence on cell viability.

Macrophage-conditioned medium enhances tunneling nanotube formation in breast cancer cells via PKC, Src, NF-κB, and p38 MAPK signaling

Tumor-associated macrophages (TAMs) secrete cytokines, chemokines, and growth factors in the tumor microenvironment (TME) to support cancer progression. Higher TAM infiltration in the breast TME is associated with a poor prognosis. Previous studies have demonstrated the role of macrophages in stimulating long-range intercellular bridges referred to as tunneling nanotubes (TNTs) in cancer cells. Intercellular communication between cancer cells via TNTs promotes cancer growth, invasion, metastasis, and therapy resistance. Given the important role of TNTs and macrophages in cancer, the role of macrophage-induced TNTs in chemotherapy drug doxorubicin resistance is not known. Furthermore, the mechanism of macrophage-mediated TNT formation is elusive. In this study, it is shown that the macrophage-conditioned medium (MΦCM) partially mimicked inflammatory TME, induced an EMT phenotype, and increased migration in MCF-7 breast cancer cells. Additionally, secreted proteins in MΦCM induced TNT formation in MCF-7 cells, which led to increased resistance to doxorubicin. Transcriptomic analysis of MΦCM-treated MCF-7 cells showed enrichment of the NF-κB and focal adhesion pathways, as well as upregulation of genes involved in EMT, extracellular remodeling, and actin cytoskeleton reorganization. Interestingly, inhibitors of PKC, Src, NF-κB, and p38 decreased macrophage-induced TNT formation in MCF-7 cells. These results reveal the novel role of PKC and Src in inducing TNT formation in cancer cells and suggest that inhibition of PKC and Src activity may likely contribute to reduced macrophage-breast cancer cell interaction and the potential therapeutic strategy of cancer.

Unveiling epithelial plasticity regulation in lung cancer: Exploring the cross-talk among Tks4 scaffold protein partners

The epithelial-to-mesenchymal transition (EMT) represents a hallmark event in the evolution of lung cancer. This work aims to study a recently described EMT-regulating protein, Tks4, and to explore its potential as a prognostic biomarker in non-small cell lung cancer. In this study, we used CRISPR/Cas9 method to knockout (KO) Tks4 to study its functional roles in invadopodia formation, migration, and regulation of EMT marker expressions and we identified Tks4-interacting proteins. Tks4-KO A549 cells exhibited an EMT-like phenotype characterized by elongated morphology and increased expression of EMT markers. Furthermore, analyses of a large-scale lung cancer database and a patient-derived tissue array data revealed that the Tks4 mRNA level was decreased in more aggressive lung cancer stages. To understand the regulatory role of Tks4 in lung cancer, we performed a Tks4-interactome analysis via Tks4 immunoprecipitation-mass spectrometry on five different cell lines and identified CAPZA1 as a novel Tks4 partner protein. Thus, we propose that the absence of Tks4 leads to disruption of a connectome of multiple proteins and that the resulting undocking and likely mislocalization of signaling molecules impairs actin cytoskeleton rearrangement and activates EMT-like cell fate switches, both of which likely influence disease severity.

The mechanism of the contribution of ICAM-1 to epithelial-mesenchymal transition (EMT) in bladder cancer

Bladder cancer is one of the most prevalent cancers worldwide. Moreover, if not optimally treated, bladder cancer is a significant burden on healthcare systems due to multiple recurrences which often require more aggressive therapies. Therefore, targeted anti-cancer therapies, developed based on an in-depth understanding of specific proteins and molecular mechanisms, are promising in cancer treatment. Here, for the first time, we presented the new approaches indicating that intracellular adhesion molecule-1 (ICAM-1) may play a potential role in enhancing therapeutic effectiveness for bladder cancer. In the present study, we presented that ICAM-1 expression as well as its regulation in bladder cancer is strongly correlated with the high expression of N-cadherin. Importantly, the presence of N-cadherin and its regulator-TWIST-1 was abolished when ICAM-1 was silenced. We identified also that ICAM-1 is capable of regulating cellular migration, proliferation, and EMT progression in bladder cancer cells via the N-cadherin/SRC/AKT/GSK-3β/β-catenin signaling axis. Therefore, we propose ICAM-1 as a novel metastatic marker for EMT progression, which may also be used as a therapeutic target in bladder cancer.

Dasatinib suppresses collective cell migration through the coordination of focal adhesion and E-cadherin in colon cancer cells

Collective cell migration is an important process in cancer metastasis. Unlike single-cell migration, collective cell migration requires E-cadherin expression in the cell cohort. However, the mechanisms underlying cellular contact and focal adhesions remain unclear. In this study, Src was hypothesized to coordinate focal adhesion and Rab11-mediated E-cadherin distribution during collective cell migration. This study primarily used confocal microscopy to visualize the 3D structure of cell-cell contacts with associated molecules. These results demonstrate that the clinical Src inhibitor dasatinib was less toxic to HT-29 colon cancer cells; instead, the cells aggregated. 3D immunofluorescence imaging showed that Rab11 was localized with E-cadherin at the adherens junctions of the apical cell-cell contacts. In the transwell assay, Rab11 colocalized with a broad range of E-cadherin proteins in collectively migrated cells, and dasatinib treatment significantly suppressed collective cell migration. Transmission electron microscopy demonstrated that dasatinib treatment increased cell membrane protrusion contacts and generated spaces between cells, which may allow epidermal growth factor receptor activity at the cell-cell contacts. This study suggests that dasatinib treatment does not inhibit cell survival but targets Src at different cellular compartments in the coordination of focal adhesions and cell-cell contacts in collective cell migration through E-cadherin dynamics in colon cancer cells.

Root Extract of Trichosanthes kirilowii Suppresses Metastatic Activity of EGFR TKI-Resistant Human Lung Cancer Cells by Inhibiting Src-Mediated EMT

The roots of Trichosanthes kirilowii (TK) have been used in traditional oriental medicine for the treatment of respiratory diseases. In this study, we investigated whether an ethanolic root extract of TK (ETK) can regulate the metastatic potency of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI)-resistant human lung cancer cells. The relative migration and invasion abilities of erlotinib-resistant PC9 (PC9/ER) and gefitinib-resistant PC9 (PC9/GR) cells were higher than those of parental PC9 cells. Mesenchymal markers were overexpressed, whereas epithelial markers were downregulated in resistant cells, suggesting that resistant cells acquired the EMT phenotype. ETK reduced migration and invasion of resistant cells. The expression levels of N-cadherin and Twist were downregulated, whereas Claudin-1 was upregulated by ETK, demonstrating that ETK suppresses EMT. As a molecular mechanism, Src was dephosphorylated by ETK. The anti-metastatic effect of ETK was reduced by transfecting PC9/ER cells with a constitutively active form of c-Src. Dasatinib downregulated N-cadherin, Twist, and vimentin, suggesting that Src regulates EMT in resistant cells. Notably, CuB played a key role in mediating the anti-metastatic activity of ETK. Collectively, our results demonstrate that ETK can attenuate the metastatic ability of EGFR-TKI-resistant lung cancer cells by inhibiting Src-mediated EMT.

Epithelial-to-Mesenchymal Transition-Related Markers in Prostate Cancer: From Bench to Bedside

Prostate cancer (PCa) is the second most frequent type of cancer in men worldwide, with 288,300 new cases and 34,700 deaths estimated in the United States in 2023. Treatment options for early-stage disease include external beam radiation therapy, brachytherapy, radical prostatectomy, active surveillance, or a combination of these. In advanced cases, androgen-deprivation therapy (ADT) is considered the first-line therapy; however, PCa in most patients eventually progresses to castration-resistant prostate cancer (CRPC) despite ADT. Nonetheless, the transition from androgen-dependent to androgen-independent tumors is not yet fully understood. The physiological processes of epithelial-to-non-epithelial ("mesenchymal") transition (EMT) and mesenchymal-to-epithelial transition (MET) are essential for normal embryonic development; however, they have also been linked to higher tumor grade, metastatic progression, and treatment resistance. Due to this association, EMT and MET have been identified as important targets for novel cancer therapies, including CRPC. Here, we discuss the transcriptional factors and signaling pathways involved in EMT, in addition to the diagnostic and prognostic biomarkers that have been identified in these processes. We also tackle the various studies that have been conducted from bench to bedside and the current landscape of EMT-targeted therapies.

An Ethanol Extract of Perilla frutescens Leaves Suppresses Adrenergic Agonist-Induced Metastatic Ability of Cancer Cells by Inhibiting Src-Mediated EMT

Previous studies have indicated that the adrenergic receptor signaling pathway plays a fundamental role in chronic stress-induced cancer metastasis. In this study, we investigated whether an ethanol extract of Perilla frutescens leaves (EPF) traditionally used to treat stress-related symptoms by moving Qi could regulate the adrenergic agonist-induced metastatic ability of cancer cells. Our results show that adrenergic agonists including norepinephrine (NE), epinephrine (E), and isoproterenol (ISO) increased migration and invasion of MDA-MB-231 human breast cancer cells and Hep3B human hepatocellular carcinoma cells. However, such increases were completely abrogated by EPF treatment. E/NE induced downregulation of E-cadherin and upregulation of N-cadherin, Snail, and Slug. Such effects were clearly reversed by pretreatment with EPF, suggesting that the antimetastatic activity of EPF could be related to epithelial-mesenchymal transition (EMT) regulation. EPF suppressed E/NE-stimulated Src phosphorylation. Inhibition of Src kinase activity with dasatinib completely suppressed the E/NE-induced EMT process. Transfecting MDA-MB-231 cells with constitutively activated Src (SrcY527F) diminished the antimigration effect of EPF. Taken together, our results demonstrate that EPF can suppress the adrenergic agonist-promoted metastatic ability of cancer cells by inhibiting Src-mediated EMT. This study provides basic evidence supporting the probable use of EPF to prevent metastasis in cancer patients, especially those under chronic stress.

c-Src inhibitor PP2 inhibits head and neck cancer progression through regulation of the epithelial-mesenchymal transition

Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancer, causing considerable mortality and morbidity worldwide. Although HNSCC management has been extensively studied, the treatment outcomes have not improved - the 5-year survival rate of patients with HNSCC is 40%. Recent studies on the development of a novel HNSCC treatment have highlighted proto-oncogene tyrosine-protein kinase Src (c-Src) as one of the major therapeutic targets. However, the clinical efficacy of c-Src inhibitors against HNSCC was not comparable to that obtained in vitro. Furthermore, the molecular mechanisms underlying the efficacy of c-Src inhibitors remain elusive. In this study, we assessed the efficacy of 4-amino-5-(4-chlorophenyl)-7-(dimethylethyl)pyrazolo[3,4-d] pyrimidine (PP2), a selective c-Src inhibitor on HSNCC. Nine HNSCC cell lines (SNU1041, Fraud, SNU46, SNU1076, SNU899, SCC1483, YD15, YD9, and YD10-) were screened, and the effects of PP2 were evaluated using wound healing, apoptosis, and invasion assays. Western blot analysis of downstream markers was conducted to assess the specific mechanism of action of PP2 in HNSCC. The therapeutic efficacy of PP2 was further evaluated in xenograft mice. PP2 reduced tumor cell growth both in vitro and in vivo. Furthermore, it enhanced tumor cell apoptosis in cell lines and prevented metastasis in mice. PP2 also regulated the epithelial-mesenchymal transition pathway downstream of c-Src. More specifically, in SCC1483 and YD15PP2 HNSCC cell lines, PP2 exposure downregulated Erk, Akt/Slug, and Snail but upregulated E-cadherin. These results suggest that PP2 inhibits cell growth and progression in HNSCC by regulating the epithelial-mesenchymal transition pathway.

A Phase I Study of the Non-Receptor Kinase Inhibitor Bosutinib in Combination with Pemetrexed in Patients with Selected Metastatic Solid Tumors

Src is overexpressed in various cancers, including 27% of non-small cell lung cancer NSCLC, and is correlated with poor clinical outcomes. We hypothesize that Src kinase inhibitors, including Bosutinib, may exhibit clinical synergy in combination with the antifolate drug pemetrexed. In this Phase I, dose-escalation, safety, and maximum tolerated dose (MTD)-determining study, 14 patients with advanced metastatic solid tumors that had progressed on "standard of care" chemotherapy were enrolled in a 3 + 3 dose escalation study. Oral Bosutinib was administered once daily beginning on day 1, where the first cohort started at an oral dose of 200 mg daily with pemetrexed 500 mg/m² IV on a three-week schedule. The study's primary objective was to determine the dose-limiting toxicity (DLT), the MTD of Bosutinib in combination with pemetrexed, and the type and frequency of adverse events associated with this treatment. Twelve patients were evaluable for response, including ten patients with adenocarcinoma of the lung, one patient with metastatic adenocarcinoma of the appendix, and one patient with urothelial carcinoma. The median number of Bosutinib and pemetrexed cycles received was 4 (range, 1-4). The MTD of oral Bosutinib in this combination was 300 mg daily. Two patients (17%) had a partial response (PR), and seven patients (58%) showed stable disease (SD) as the best response after the fourth cycle (end of treatment). One patient had disease progression after the second cycle, while three patients had disease progression after the fourth cycle. The two responders and the two patients with the longest stable disease duration or stabilization of disease following progression on multiple systemic therapies demonstrated Src overexpression on immunohistochemical staining of their tumor. The median progression-free survival (PFS) was 6.89 months (95% CI (3.48, 30.85)), and the median overall survival (OS) was 11.7 months (95% CI (3.87, 30.85)). Despite the limitations of this Phase I study, there appears to be potential efficacy of this combination in previously treated patients.

Terminalia catappa leaf extracts inhibited metastasis of A2058 and A375 melanoma cells via downregulating p-Src and β-catenin pathway in vitro

Background: Melanoma is a highly aggressive, lethal, and malignant cancer. Once diagnosed early, it can be easily removed and cured with satisfaction. Although many methods such as surgery, chemotherapy, radiotherapy, and immunotherapy have been used to treat this disease at an advanced stage, the outcomes are poor. Terminalia catappa leaves have been shown to have various biological benefits, including antitumor activity. The specific effects and molecular mechanisms of Terminalia catappa leaf in treating A2058 and A375 melanoma cells in vitro need to be clarified.

Methods: The A2058 and A375 melanoma cancer cells were treated with Terminalia catappa leaf extracts, and then the effect of Terminalia catappa leaf extracts on migration and invasion was examined. The cell migration/invasion capacities of A2058 and A375 cells were investigated by a modified Boyden chamber assay. Zymography was used to clarify the activities of matrix metalloproteinases-2 and urinary type plasminogen activator. We performed a Western blot to verify the related expression of phospho-Src (Tyr416), phospho-Focal adhesion kinase (Tyr397), Vimentin, and β-catenin.

Results: Modified Boyden chamber assays demonstrated that treatment of Terminalia catappa leaf extracts significantly inhibited A2058 and A375 cell migration/invasion capacities. In the zymography results, we showed that Terminalia catappa leaf extracts negatively modulated the activities of matrix metalloproteinases-2 and urinary type plasminogen activator. Western blot indicated that Terminalia catappa leaf extracts reduced the expression of phospho-Src (Tyr416), phospho-Focal adhesion kinase (Tyr397), Vimentin, and β-catenin.

Conclusion:Terminalia catappa leaf extracts affected the antimetastasis of the A2058 and A375 melanoma cell lines by inhibiting the Focal adhesion kinase/Src interaction and Wingless-int1/β-catenin pathways in vitro. Terminalia catappa leaf extracts may serve as an effective chemopreventive agent against metastasis of melanoma cancer.

The Effects of Quercetin on the Apoptosis of Human Breast Cancer Cell Lines MCF-7 and MDA-MB-231: A Systematic Review

This systematic review was performed with a focus on the effects of quercetin (QT) on the human breast cancer cell lines MCF-7 and MDA-MB-231. PubMed, Scopus, Science Direct, and Google Scholar databases were searched up to May 2020 using relevant keywords. All articles written in English evaluating the effects of QT on the human breast cancer cell lines MCF-7 and/or MDA-MB-231 were eligible for the review. Totally, 31 articles were included in this review. Out of them, 23 studies investigated the effects of QT on MCF-7 cells and indicated that QT induces apoptosis in the cells. Of 15 studies that examined the effects of QT on MDA-MB-231 cells, 14 reports showed successful apoptosis. It is concluded that QT might be beneficial in the eliminating of breast cancer cells. However, further clinical trials are warranted to further verify these outcomes.

Worm-Based Microfluidic Biosensor for Real-Time Assessment of the Metastatic Status

Simple Summary

We proposed a high-throughput screening and low-cost worm-based (WB) microfluidic biosensor to monitor biochemical cues related to metastasis. Caenorhabditis elegans placed in the WB biosensor chambers and exposed to samples conditioned with cancer cell clusters reflect differences in the chemotactic preference of worms. We observed a higher distribution of worms associated with samples of higher metastatic potential (p < 0.005). A chemotaxis index (CI) was defined to standardize the quantitative assessment from the WB biosensor, where increased metastatic potential was associated with higher CI levels (6.5 ± 1.37). We found that the secreted metabolite glutamate was a chemorepellent, and lower glutamate levels were associated with samples derived from more metastatic cancer cell clusters. In conclusion, WB biosensors could evaluate patient status in real time, thereby facilitating early detection of metastases and routine management.

Abstract

Background: Metastasis is a complex process that affects patient treatment and survival. To routinely monitor cancer plasticity and guide treatment strategies, it is highly desired to provide information about metastatic status in real-time. Here, we proposed a worm-based (WB) microfluidic biosensor to rapidly monitor biochemical cues related to metastasis in a well-defined environment. Compared to conventional biomarker-based methods, the WB biosensor allowed high throughput screening under low cost, requiring only visual quantification of outputs; Methods: Caenorhabditis elegans were placed in the WB biosensor and exposed to samples conditioned with cancer cell clusters. The chemotactic preference of these worms was observed under discontinuous imaging to minimize the impact on physiological activity; Results: A chemotaxis index (CI) was defined to standardize the quantitative assessment from the WB biosensor, where moderate (3.24–6.5) and high (>6.5) CI levels reflected increased metastasis risk and presence of metastasis, respectively. We demonstrated that the secreted metabolite glutamate was a chemorepellent, and larger clusters associated with increased metastatic potential also enhanced CI levels; Conclusions: Overall, this study provided a proof of concept for the WB biosensors in assessing metastasis status, with the potential to evaluate patient-derived cancer clusters for routine management.

c-Src promotes the growth and tumorigenesis of hepatocellular carcinoma via the Hippo signaling pathway

We investigated the association between c-Src and the progression of hepatocellular carcinoma (HCC) and its underlying mechanisms. The relationship between c-Src expression and the occurrence and development of HCC was explored using GEPIA and further confirmed by western blotting analysis and real-time quantitative PCR. CCK-8, flow cytometry, Transwell, and wound-healing assays were conducted to analyze the effects of c-Src on the growth, cell cycle, apoptosis, migration, and infiltration of HCC cells. Mouse models of transplanted xenogeneic human tumors were constructed to explore the effects of c-Src on HCC tumor growth. Compared with that in adjacent normal liver tissues, the expression level of c-Src in HCC tissues was significantly increased and was negatively correlated with patient survival. These findings are consistent with those in the GEPIA database. Downregulation of c-Src expression can inhibit the growth, infiltration, and migration of HCC cells. c-Src impeded the translocation of YAP from the nucleus to the cytoplasm and promoted Yes-associated protein transcriptional activity. In vivo experiments showed that c-Src inhibition suppressed tumor growth in mice. We found that c-Src can promote the growth and tumorigenesis of HCC cells by activating the Hippo signaling pathway.

How Different Are the Molecular Mechanisms of Nodal and Distant Metastasis in Luminal A Breast Cancer?

Lymph node status is one of the best prognostic factors in breast cancer, however, its association with distant metastasis is not straightforward. Here we compare molecular mechanisms of nodal and distant metastasis in molecular subtypes of breast cancer, with major focus on luminal A patients. We analyze a new cohort of 706 patients (MMCI_706) as well as an independent cohort of 836 primary tumors with full gene expression information (SUPERTAM_HGU133A). We evaluate the risk of distant metastasis, analyze targetable molecular mechanisms in Gene Set Enrichment Analysis and identify relevant inhibitors. Lymph node positivity is generally associated with NF-κB and Src pathways and is related to high risk (OR: 5.062 and 2.401 in MMCI_706 and SUPERTAM_HGU133A, respectively, p < 0.05) of distant metastasis in luminal A patients. However, a part (≤15%) of lymph node negative tumors at the diagnosis develop the distant metastasis which is related to cell proliferation control and thrombolysis. Distant metastasis of lymph node positive patients is mostly associated with immune response. These pro-metastatic mechanisms further vary in other molecular subtypes. Our data indicate that the management of breast cancer and prevention of distant metastasis requires stratified approach based on targeted strategies.

Src Family Kinases as Therapeutic Targets in Advanced Solid Tumors: What We Have Learned so Far

Src is the prototypal member of Src Family tyrosine Kinases (SFKs), a large non-receptor kinase class that controls multiple signaling pathways in animal cells. SFKs activation is necessary for the mitogenic signal from many growth factors, but also for the acquisition of migratory and invasive phenotype. Indeed, oncogenic activation of SFKs has been demonstrated to play an important role in solid cancers; promoting tumor growth and formation of distant metastases. Several drugs targeting SFKs have been developed and tested in preclinical models and many of them have successfully reached clinical use in hematologic cancers. Although in solid tumors SFKs inhibitors have consistently confirmed their ability in blocking cancer cell progression in several experimental models; their utilization in clinical trials has unveiled unexpected complications against an effective utilization in patients. In this review, we summarize basic molecular mechanisms involving SFKs in cancer spreading and metastasization; and discuss preclinical and clinical data highlighting the main challenges for their future application as therapeutic targets in solid cancer progression

Fluid flow-induced activation of subcellular AMPK and its interaction with FAK and Src

AMP-activated protein kinase (AMPK) is a metabolic energy sensor that plays a critical role in cancer cell survival and growth. While the physical microenvironment is believed to influence tumor growth and progression, its role in AMPK regulation remains largely unknown. In the present study, we evaluated AMPK response to mechanical forces and its interaction with other mechano-responsive signaling proteins, FAK and Src. Using genetically encoded biosensors that can detect AMPK activities at different subcellular locations (cytosol, plasma membrane, nucleus, mitochondria, and Golgi apparatus), we observed that AMPK responds to shear stress in a subcellular location-dependent manner in breast cancer cells (MDA-MB-231). While normal epithelial cells (MCF-10A) also similarly responded to shear stress, they are less sensitive to shear stress compared to MDA-MB-231 cells. Inhibition of FAK and Src significantly decreased the basal activity level of AMPK at all five subcellular locations in MDA-MB-231 cells and selectively blocked shear stress-induced AMPK activation. Moreover, testing with cytoskeletal drugs revealed that myosin II might be the critical mediator of shear stress-induced AMPK activation in MDA-MB-231 cells. These findings suggest that breast cancer cells and normal epithelial cells may have different mechanosensitivity in AMPK signaling and that FAK and Src as well as the myosin II-dependent signaling pathway are involved in subcellular AMPK mechanotransduction in breast cancer cells.

c-Met activation leads to the establishment of a TGFβ-receptor regulatory network in bladder cancer progression

Treatment of muscle-invasive bladder cancer remains a major clinical challenge. Aberrant HGF/c-MET upregulation and activation is frequently observed in bladder cancer correlating with cancer progression and invasion. However, the mechanisms underlying HGF/c-MET-mediated invasion in bladder cancer remains unknown. As part of a negative feedback loop SMAD7 binds to SMURF2 targeting the TGFβ receptor for degradation. Under these conditions, SMAD7 acts as a SMURF2 agonist by disrupting the intramolecular interactions within SMURF2. We demonstrate that HGF stimulates TGFβ signalling through c-SRC-mediated phosphorylation of SMURF2 resulting in loss of SMAD7 binding and enhanced SMURF2 C2-HECT interaction, inhibiting SMURF2 and enhancing TGFβ receptor stabilisation. This upregulation of the TGFβ pathway by HGF leads to TGFβ-mediated EMT and invasion. In vivo we show that TGFβ receptor inhibition prevents bladder cancer invasion. Furthermore, we make a rationale for the use of combinatorial TGFβ and MEK inhibitors for treatment of high-grade non-muscle-invasive bladder cancers.

Dasatinib inhibition of cSRC prevents the migration and metastasis of canine mammary cancer cells with enhanced Wnt and HER signalling

Human epidermal growth factor 2 (HER2) overexpression leads to aggressive mammary tumour growth. Although the prognosis of HER2⁺ tumours in humans is greatly improved using biologicals, therapy resistance, which may be caused by increased phosphatidyl-3-kinase (PI3K), rous sarcoma proto-oncogene (cSRC) or wingless-type MMTV integration site family (Wnt) activity, is a major concern. A recent analysis of 12 canine mammary cell lines showed an association between HER2/3 overexpression and phosphatase and tensin homologue (PTEN) deletion with elevated Wnt-signalling. Wnt-activity appeared to be insensitive to phosphatidyl-3-kinase (PI3K) inhibitors but sensitive to Src-I1. We hypothesized that Wnt activation, was caused by HER2/3-activated cSRC activation. The role of HER2/3 on Wnt signalling was investigated by silencing HER2/3 expression using specific small interfering RNA (siRNAs). Next, the effect of an epidermal growth factor receptor (EGFR)/HER2 tyrosine kinase inhibitor on Wnt activity and migration was investigated and compared to other tyrosine kinase inhibitors (TKIs) of related signalling pathways. Finally, two TKIs, a cSRC and a PI3K inhibitor, were investigated in a zebrafish xenograft model. Silencing of HER1-3 did not inhibit the intrinsic high Wnt activity, whereas the HER kinase inhibitor afatinib showed enhanced Wnt activity. The strongest inhibition of Wnt activity and cell viability and migration was shown by cSRC inhibitors, which also showed strong inhibition of cell viability and metastasis in a zebrafish xenograft model. HER2/3 overexpression or HER2/3-induced cSRC activation is not the cause of enhanced Wnt activity. However, inhibition of cSRC resulted in a strong inhibition of Wnt activity and cell migration and metastasis. Further studies are needed to unravel the mechanism of cSRC activation and cSRC inhibition to restore sensitivity to HER-inhibitors in HER2/3-positive breast cancer.

The Root Bark of Morus alba L. Suppressed the Migration of Human Non-Small-Cell Lung Cancer Cells through Inhibition of Epithelial⁻Mesenchymal Transition Mediated by STAT3 and Src

The root bark of Morus alba L. (MA) has been traditionally used for the treatment of various lung diseases in Korea. Although recent research has demonstrated its anticancer effects in several cancer cells, it is still unclear whether MA inhibits the migratory ability of lung cancer cells. The present study investigated the effects of MA on the migration of lung cancer cells and explored the underlying mechanism. Results from a transwell assay and wound-healing assay demonstrated that methylene chloride extracts of MA (MEMA) suppressed the migration and invasion of H1299, H460, and A549 human non-small-cell lung cancer (NSCLC) cells in a concentration-dependent manner. Results from Western blot analyses showed that MEMA reduced the phosphorylation of STAT3 and Src. In addition, MEMA downregulated the expression of epithelial–mesenchymal transition (EMT) marker proteins including Slug, Snail, Vimentin, and N-cadherin, while upregulating the expression of Occludin—a tight-junction protein. The regulation of EMT markers and the decrease of migration by MEMA treatment were reversed once phospho-mimetic STAT3 (Y705D) or Src (Y527F) was transfected into H1299 cells. In conclusions, MEMA inhibited the migratory activity of human NSCLC cells through blocking Src/STAT3-mediated EMT.

CCR2 Chemokine Receptors Enhance Growth and Cell-Cycle Progression of Breast Cancer Cells through SRC and PKC Activation

Basal-like breast cancers are an aggressive breast cancer subtype, which often lack estrogen receptor, progesterone receptor, and Her2 expression, and are resistant to antihormonal and targeted therapy, resulting in few treatment options. Understanding the underlying mechanisms that regulate progression of basal-like breast cancers would lead to new therapeutic targets and improved treatment strategies. Breast cancer progression is characterized by inflammatory responses, regulated in part by chemokines. The CCL2/CCR2 chemokine pathway is best known for regulating breast cancer progression through macrophage-dependent mechanisms. Here, we demonstrated important biological roles for CCL2/CCR2 signaling in breast cancer cells. Using the MCF10CA1d xenograft model of basal-like breast cancer, primary tumor growth was significantly increased with cotransplantation of patient-derived fibroblasts expressing high levels of CCL2, and was inhibited with CRISP/R gene ablation of stromal CCL2. CRISP/R gene ablation of CCR2 in MCF10CA1d breast cancer cells inhibited breast tumor growth and M2 macrophage recruitment and validated through CCR2 shRNA knockdown in the 4T1 model. Reverse phase protein array analysis revealed that cell-cycle protein expression was associated with CCR2 expression in basal-like breast cancer cells. CCL2 treatment of basal-like breast cancer cell lines increased proliferation and cell-cycle progression associated with SRC and PKC activation. Through pharmacologic approaches, we demonstrated that SRC and PKC negatively regulated expression of the cell-cycle inhibitor protein p27KIP1, and are necessary for CCL2-induced breast cancer cell proliferation. IMPLICATIONS: This report sheds novel light on CCL2/CCR2 chemokine signaling as a mitogenic pathway and cell-cycle regulator in breast cancer cells.

Epithelial mesenchymal transition (EMT): a universal process in lung diseases with implications for cystic fibrosis pathophysiology

Cystic Fibrosis (CF) is a genetic disorder that arises due to mutations in the Cystic Fibrosis Transmembrane Conductance Regulator gene, which encodes for a protein responsible for ion transport out of epithelial cells. This leads to a disruption in transepithelial Cl-, Na + and HCO₃− ion transport and the subsequent dehydration of the airway epithelium, resulting in infection, inflammation and development of fibrotic tissue. Unlike in CF, fibrosis in other lung diseases including asthma, chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis has been well characterised. One of the driving forces behind fibrosis is Epithelial Mesenchymal Transition (EMT), a process where epithelial cells lose epithelial proteins including E-Cadherin, which is responsible for tight junctions. The cell moves to a more mesenchymal phenotype as it gains mesenchymal markers such as N-Cadherin (providing the cells with migration potential), Vimentin and Fibronectin (proteins excreted to help form the extracellular matrix), and the fibroblast proliferation transcription factors Snail, Slug and Twist. This review paper explores the EMT process in a range of lung diseases, details the common links that these have to cystic fibrosis, and explores how understanding EMT in cystic fibrosis may open up novel methods of treating patients with cystic fibrosis.

MicroRNA-1271 functions as a metastasis and epithelial-mesenchymal transition inhibitor in human HCC by targeting the PTP4A1/c-Src axis

MicroRNAs (miRNAs or miRs) have been shown to regulate hepatocellular carcinoma (HCC) metastasis. In the present study, we focused on the functions of miR-1271 in HCC metastasis. The downregulation of miR-1271 was found to be associated with to venous infiltration, an advanced TNM stage (III+IV stage) and a shorter survival time. Our in vitro and in vivo data demonstrated that miR-1271 prevented HCC cell migration and invasion, as well as the formation of lung metastatic clusters. In addition, miR-1271 was demonstrated to markedly inhibit the epithelial-mesenchymal transition (EMT) of HCC cells. Importantly, protein tyrosine phosphatase type IVA member 1 (PTP4A1) was identified as a direct downstream target of miR-1271 in HCC. Furthermore, we confirmed that the phosphorylation of c-Src at Tyr416 mediated by PTP4A1 was a potential anti-HCC mechanism of action of miR-1271. On the whole, our data indicate that miR-1271 inhibits HCC metastasis by targeting the PTP4A1/c-Src signaling pathway and may serve as a prospective cancer therapeutic target for HCC.

Src promotes EGF-induced epithelial-to-mesenchymal transition and migration in gastric cancer cells by upregulating ZEB1 and ZEB2 through AKT

Epithelial-to-mesenchymal transition (EMT) plays important roles in the migration, invasion, and metastasis of cancer cells. However, the role of Src in epidermal growth factor (EGF)-induced EMT and migration in gastric cancer cells remains to be clarified. In the current study, the effect of Src on EGF-stimulated EMT and migration was explored in gastric cancer cells. EGF induced EMT in gastric cancer cells and increased their migratory ability, which was accompanied by the phosphorylation of Src. PP2, the Src inhibitor, markedly suppressed EGF-mediated EMT and migration in gastric cancer cells. Additionally, EGF-stimulated upregulation of zinc finger E-box binding homeobox 1 (ZEB1) and zinc finger E-box binding homeobox 2 (ZEB2) was significantly repressed by PP2. Further analysis showed that EGF-stimulated phosphorylation of protein kinase B (AKT) was almost completely abolished by PP2, whereas that of extracellular signal-regulated kinase (ERK), signal transducer and activator of transcription 3 (STAT3) was only mildly suppressed. Moreover, LY294002, the AKT inhibitor, significantly inhibited EGF-induced upregulation of ZEB1 and ZEB2 as well as EMT and migration stimulated by EGF in gastric cancer cells. However, neither ERK inhibitor nor STAT3 inhibitor repressed EGF-induced EMT-related changes. Taken together, these results suggest that Src promotes EGF-stimulated EMT and migration by upregulation of ZEB1 and ZEB2 through AKT signaling pathway in gastric cancer cells.

Dual Src Kinase/Pretubulin Inhibitor KX-01, Sensitizes ERα-negative Breast Cancers to Tamoxifen through ERα Reexpression

Unlike breast cancer that is positive for estrogen receptor-α (ERα), there are no targeted therapies for triple-negative breast cancer (TNBC). ERα is silenced in TNBC through epigenetic changes including DNA methylation and histone acetylation. Restoring ERα expression in TNBC may sensitize patients to endocrine therapy. Expression of c-Src and ERα are inversely correlated in breast cancer suggesting that c-Src inhibition may lead to reexpression of ERα in TNBC. KX-01 is a peptide substrate-targeted Src/pretubulin inhibitor in clinical trials for solid tumors. KX-01 (1 mg/kg body weight-twice daily) inhibited growth of tamoxifen-resistant MDA-MB-231 and MDA-MB-157 TNBC xenografts in nude mice that was correlated with Src kinase inhibition. KX-01 also increased ERα mRNA and protein, as well as increased the ERα targets progesterone receptor (PR), pS2 (TFF1), cyclin D1 (CCND1), and c-myc (MYC) in MDA-MB-231 and MDA-MB-468, but not MDA-MB-157 xenografts. MDA-MB-231 and MDA-MB-468 tumors exhibited reduction in mesenchymal markers (vimentin, β-catenin) and increase in epithelial marker (E-cadherin) suggesting mesenchymal-to-epithelial transition (MET). KX-01 sensitized MDA-MB-231 and MDA-MB-468 tumors to tamoxifen growth inhibition and tamoxifen repression of the ERα targets pS2, cyclin D1, and c-myc. Chromatin immunoprecipitation (ChIP) of the ERα promoter in KX-01-treated tumors demonstrated enrichment of active transcription marks (acetyl-H3, acetyl-H3Lys9), dissociation of HDAC1, and recruitment of RNA polymerase II. Methylation-specific PCR and bisulfite sequencing demonstrated no alteration in ERα promoter methylation by KX-01. These data demonstrate that in addition to Src kinase inhibition, peptidomimetic KX-01 restores ERα expression in TNBC through changes in histone acetylation that sensitize tumors to tamoxifen.Implications: Src kinase/pretubulin inhibitor KX-01 restores functional ERα expression in ERα^- breast tumors, a novel treatment strategy to treat triple-negative breast cancer. Mol Cancer Res; 15(11); 1491-502. ©2017 AACR.

Novel roles of Src in cancer cell epithelial-to-mesenchymal transition, vascular permeability, microinvasion and metastasis

The Src-family kinases (SFKs), an intracellularly located group of non-receptor tyrosine kinases are involved in oncogenesis. The importance of SFKs has been implicated in the promotion of tumor cell motility, proliferation, inhibition of apoptosis, invasion and metastasis. Recent evidences indicate that specific effects of SFKs on epithelial-to-mesenchymal transition (EMT) as well as on endothelial and stromal cells in the tumor microenvironment can have profound effects on tumor microinvasion and metastasis. Although, having been studied extensively, these novel features of SFKs may contribute to greater understanding of benefits from Src inhibition in various types of cancers. Here we review the novel role of SFKs, particularly c-Src in mediating EMT, modulation of tumor endothelial-barrier, transendothelial migration (microinvasion) and metastasis of cancer cells, and discuss the utility of Src inhibitors in vascular normalization and cancer therapy.

Effect of Cigarette Smoking on Epithelial to Mesenchymal Transition (EMT) in Lung Cancer

Epithelial to mesenchymal transition (EMT) is a process that allows an epithelial cell to acquire a mesenchymal phenotype through multiple biochemical changes resulting in an increased migratory capacity. During cancer progression, EMT is found to be associated with an invasive or metastatic phenotype. In this review, we focus on the discussion of recent studies about the regulation of EMT by cigarette smoking. Various groups of active compounds found in cigarette smoke such as polycyclic aromatic hydrocarbons (PAH), nicotine-derived nitrosamine ketone (NNK), and reactive oxygen specicies (ROS) can induce EMT through different signaling pathways. The links between EMT and biological responses to cigarette smoke, such as hypoxia, inflammation, and oxidative damages, are also discussed. The effect of cigarette smoke on EMT is not only limited to cancer types directly related to smoking, such as lung cancer, but has also been found in other types of cancer. Altogether, this review emphasizes the importance of understanding molecular mechanisms of the induction of EMT by cigarette smoking and will help in identifying novel small molecules for targeting EMT induced by smoking.

Cancer Stem Cells Protect Non-Stem Cells From Anoikis: Bystander Effects

Cancer stem cells (CSCs) are capable of initiation and metastasis of tumors. Therefore, understanding the biology of CSCs and the interaction between CSCs and their counterpart non-stem cells is crucial for developing a novel cancer therapy. We used CSC-like and non-stem breast cancer MDA-MB-231 and MDA-MB-453 cells to investigate mammosphere formation. We investigated the role of the epithelial cadherin (E-cadherin)-extracellular signal-regulated kinase (Erk) axis in anoikis. Data from E-cadherin small hairpin RNA assay and mitogen-activated protein kinase kinase (MEK) inhibitor study show that activation of Erk, but not modulation of E-cadherin level, may play an important role in anoikis resistance. Next, the two cell subtypes were mixed and the interaction between them during mammosphere culture and xenograft tumor formation was investigated. Unlike CSC-like cells, increased secretion of interleukin-6 (IL-6) and growth-related oncogene (Gro) chemokines was detected during mammosphere culture in non-stem cells. Similar results were observed in mixed cells. Interestingly, CSC-like cells protected non-stem cells from anoikis and promoted tumor growth. Our results suggest bystander effects between CSC-like cells and non-stem cells. J. Cell. Biochem. 117: 2289-2301, 2016. © 2016 Wiley Periodicals, Inc.

Chinese Herbal Medicine Treatment Improves the Overall Survival Rate of Individuals with Hypertension among Type 2 Diabetes Patients and Modulates In Vitro Smooth Muscle Cell Contractility

Type 2 diabetes (T2D) is a chronic, multifactorial, and metabolic disorder accounting for 90% diabetes cases worldwide. Among them, almost half of T2D have hypertension, which is responsible for cardiovascular disease, morbidity, and mortality in these patients. The Chinese herbal medicine (CHM) prescription patterns of hypertension individuals among T2D patients have yet to be characterized. This study, therefore, aimed to determine their prescription patterns and evaluate the CHM effect. A cohort of one million randomly sampled cases from the National Health Insurance Research Database (NHIRD) was used to investigate the overall survival rate of CHM users, and prescription patterns. After matching CHM and non-CHM users for age, gender and date of diagnosis of hypertension, 980 subjects for each group were selected. The CHM users were characterized with slightly longer duration time from diabetes to hypertension, and more cases for hyperlipidaemia. The cumulative survival probabilities were higher in CHM users than in non-CHM users. Among these top 12 herbs, Liu-Wei-Di-Huang-Wan, Jia-Wei-Xiao-Yao-San, Dan-Shen, and Ge-Gen were the most common herbs and inhibited in vitro smooth muscle cell contractility. Our study also provides a CHM comprehensive list that may be useful in future investigation of the safety and efficacy for individuals with hypertension among type 2 diabetes patients.

Quercetin Suppresses Twist to Induce Apoptosis in MCF-7 Breast Cancer Cells

Quercetin is a dietary flavonoid which exerts anti-oxidant, anti-inflammatory and anti-cancer properties. In this study, we investigated the anti-proliferative effect of quercetin in two breast cancer cell lines (MCF-7 and MDA-MB-231), which differed in hormone receptor. IC₅₀ value (37μM) of quercetin showed significant cytotoxicity in MCF-7 cells, which was not observed in MDA-MB-231 cells even at 100μM of quercetin treatment. To study the response of cancer cells to quercetin, with respect to different hormone receptors, both the cell lines were treated with a fixed concentration (40μM) of quercetin. MCF-7 cells on quercetin treatment showed more apoptotic cells with G1 phase arrest. In addition, quercetin effectively suppressed the expression of CyclinD1, p21, Twist and phospho p38MAPK, which was not observed in MDA-MB-231 cells. To analyse the molecular mechanism of quercetin in exerting an apoptotic effect in MCF-7 cells, Twist was over-expressed and the molecular changes were observed after quercetin administration. Quercetin effectively regulated the expression of Twist, in turn p16 and p21 which induced apoptosis in MCF-7 cells. In conclusion, quercetin induces apoptosis in breast cancer cells through suppression of Twist via p38MAPK pathway.

The effect of TGF-beta-induced epithelial-mesenchymal transition on the expression of intracellular calcium-handling proteins in T47D and MCF-7 human breast cancer cells

The contribution of Ca(2+) in TGF-β-induced EMT is poorly understood. We aimed to confirm the effect of TGF-β on the gene expression of intracellular calcium-handling proteins and to investigate the potential underlying mechanisms in TGF-β-induced EMT. T47D and MCF-7 cells were cultured in vitro and treated with TGF-β. The mRNA expression of EMT marker genes and intracellular calcium-handling proteins were quantified by qRT-PCR. qRT-PCR and Western blot analysis results verified the changes of EMT marker gene expression. Furthermore, we found that TGF-β induced cell morphological changes significantly with an increase of cell surface area and cell length. These results indicated that TGF-β induced EMT. The mRNA expression levels of SPCA1, SPCA2 and MCU were not influenced by TGF-β treatment, while NCX1 expression was decreased in T47D cells. In addition, the mRNA levels of SERCAs and IP3Rs were significantly changed due to TGF-β-induced EMT. The TGF-β-treated T47D cells exhibited markedly greater response to ATP than the control cells, and the descent velocity of cytosolic calcium concentration was faster in TGF-β-treated cells than in control cells. This is the first report to demonstrate that TGF-β-induced EMT in human breast cancer cells is associated with alterations in endoplasmic reticulum calcium homeostasis.

Ring finger protein 39 genetic variants associate with HIV-1 plasma viral loads and its replication in cell culture

BACKGROUND

The human immunodeficiency virus (HIV-1) exploits host proteins to complete its life cycle. Genome-wide siRNA approaches suggested that host proteins affect HIV-1 replication. However, the results barely overlapped. RING finger protein 39 (RNF39) has been identified from genome-wide association studies. However, its function during HIV-1 replication remains unclear.

METHODS AND RESULTS

We investigated the relationship between common RNF39 genetic variants and HIV-1 viral loads. The effect of RNF39 protein knockdown or overexpression on HIV-1 replication was then investigated in different cell lines. Two genetic variants were associated with HIV-1 viral loads. Patients with the ht1-GG/GG haplotype presented lower RNF39 expression levels and lower HIV-1 viral load. RNF39 knockdown inhibited HIV-1 expression.

CONCLUSIONS

RNF39 protein may be involved in HIV-1 replication as observed in genetic studies on patients with HIV-1 and in in vitro cell cultures.

Fibroblasts induce epithelial to mesenchymal transition in breast tumor cells which is prevented by fibroblasts treatment with histamine in high concentration

Epithelial to mesenchymal transition (EMT) of cancer cells is an essential process in cancer progression. Cancer cells that undergone EMT loose cell-cell contacts, acquire mesenchymal properties and develop migratory and invasive abilities. In previous studies we have demonstrated that histamine may modify the invasive phenotype of pancreatic and mammary tumor cells. In this work we proposed to investigate whether histamine may also influence the interaction between tumor cells and normal fibroblasts. The potential activation of normal CCD-1059Sk fibroblasts by histamine and EMT phenotypic changes induced in MCF-7 and MDA-MB-231 breast tumor cells by the conditioned media (CM) derived from fibroblasts were evaluated. Initially, we determined the presence of H1, H2 and H4 histamine receptors and matrix metalloproteinase 2 (MMP2) mRNA in CCD-1059Sk fibroblasts. MMP2 gelatinolytic activity, cell migration and alpha-smooth muscle actin expression were increased in fibroblasts by low doses (<1μM) and decreased by high doses (20μM) of histamine. MCF-7 cells cultured with CM from fibroblasts exhibited spindle-shaped morphology, cell spreading and cytoplasmic expression of β-catenin but there was no change in MMP2 activity and cell migration. MDA-MB-231 cells cultured with CM from fibroblasts showed a more elongated phenotype, cell spreading, cytoplasmic β-catenin, increased MMP2 activity and endogenous TGF-β1 expression, and enhanced cell migration and invasion. Notably, all these features were reversed when mammary tumor cells were cultured with CM from fibroblasts treated with 20μM histamine. In conclusion, high doses of histamine may prevent the activation of fibroblasts and also avert the EMT related changes induced in epithelial tumor cells by fibroblasts CM.

Inhibition of Src activation with cardiotoxin III blocks migration and invasion of MDA-MB-231 cells

Cardiotoxin III (CTX III), a basic polypeptide isolated from Naja naja atra venom, has been demonstrated to display anticancer activity. Breast cancer is a highly malignant carcinoma and most deaths of breast cancer are caused by metastasis. In this study, we show that CTX III blocks migration and invasion of MDA-MB-231 breast cancer cells without affecting apoptosis or cell cycle arrest. CTX III caused significant block of Src kinase activity in MDA-MB-231 cells. Moreover, CTX III treatment was correlated with reduced phosphorylation of FAK at Tyr576, 861 and 925 sites, p130(Cas) at Tyr410, and paxillin at Tyr118. CTX III also suppressed the activation of extracellular signal-regulated kinase1/2 and phosphatidylinositol 3-kinase/Akt. Consistent with inhibition of these signaling pathways and invasion, CTX III inhibited the expression of matrix metalloproteinase-9. In addition, Src specific inhibitor PP2 caused a significant decrease in the phosphorylation of FAK, p130(Cas), paxillin, PI3K/Akt, and ERK1/2. Taken together, CTX III significantly inhibited phosphorylation of Src and downstream molecules as well as cell migration and invasion. Our findings provide evidences that CTX III inhibits Src-mediated signaling pathways involved in controlling MDA-MB-231 cell migration and invasion, suggesting that it has therapeutic potential in breast cancer treatment.

c-Src regulates cell cycle proteins expression through protein kinase B/glycogen synthase kinase 3 beta and extracellular signal-regulated kinases 1/2 pathways in MCF-7 cells

We have demonstrated that c-Src suppression inhibited the epithelial to mesenchymal transition in human breast cancer cells. Here, we investigated the role of c-Src on the cell cycle progression using siRNAs and small molecule inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2). Western blot analysis demonstrated the down-regulation of cyclin D1 and cyclin E and up-regulation of p27 Kip1 after c-Src suppression by PP2. Incubation of cells in the presence of PP2 significantly blocked the phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2), protein kinase B (AKT), and glycogen synthase kinase 3 beta (GSK3β). Specific pharmacological inhibitors of MEK1/2/ERK1/2 and phosphatidylinositide 3-kinase/AKT pathways were used to demonstrate the relationship between the signal cascade and cell cycle proteins expression. The expression of cyclin D1 and cyclin E were decreased after inhibition of ERK1/2 or AKT activity, whereas the p27 Kip1 expression was increased. In addition, knockdown of c-Src by siRNAs reduced cell proliferation and phosphorylation of ERK1/2, AKT, and GSK3β. After c-Src depletion by siRNAs, we observed significant down-regulation of cyclin D1 and cyclin E, and up-regulation of p27 Kip1. These results suggest that c-Src suppression by PP2 or siRNAs may regulate the progression of cell cycle through AKT/GSK3β and ERK1/2 pathways.

Alternatively spliced protein arginine methyltransferase 1 isoform PRMT1v2 promotes the survival and invasiveness of breast cancer cells

Protein arginine methylation is catalyzed by protein arginine methyltransferases (PRMTs) and plays an important role in many cellular processes. Aberrant PRMT expression has been observed in several common cancer types; however, their precise contribution to the cell transformation process is not well understood. We previously reported that the PRMT1 gene generates several alternatively spliced isoforms, and our initial biochemical characterization of these isoforms revealed that they exhibit distinct substrate specificity and subcellular localization. We focus here on the PRMT1v2 isoform, which is the only predominantly cytoplasmic isoform, and we have found that its relative expression is increased in breast cancer cell lines and tumors. Specific depletion of PRMT1v2 using RNA interference caused a significant decrease in cancer cell survival due to an induction of apoptosis. Furthermore, depletion of PRMT1v2 in an aggressive cancer cell line significantly decreased cell invasion. We also demonstrate that PRMT1v2 overexpression in a non-aggressive cancer cell line was sufficient to render them more invasive. Importantly, this novel activity is specific to PRMT1v2, as overexpression of other isoforms did not enhance invasion. Moreover, this activity requires both proper subcellular localization and methylase activity. Lastly, PRMT1v2 overexpression altered cell morphology and reduced cell-cell adhesion, a phenomenon that we convincingly linked with reduced β-catenin protein expression. Overall, we demonstrate a specific role for PRMT1v2 in breast cancer cell survival and invasion, underscoring the importance of identifying and characterizing the distinct functional differences between PRMT1 isoforms.

Involvement of the Src-cortactin pathway in migration induced by IGF-1 and EGF in human breast cancer cells

Cancer cells need to become motile in order to escape the primary tumor and move to distant areas to form metastasis. They move as single cells or as a group, following different stimuli, including growth factors. Among them, insulin-like growth factor‑1 (IGF-1) and epidermal growth factor (EGF) and their receptors have been implicated in the development and progression of human breast carcinoma. In this report, we provide evidence that the tyrosine kinase Src is responsible for migration promoted by both IGF-1 and EGF in MDA-MB-231 and MCF7 cells, although with a different effect. Moreover, both IGF-1 and EGF induce reorganization of actin cytoskeleton in lamellipodia and membrane ruffles in a time- and Src-dependent manner. Furthermore, we analyzed the tyrosine phosphorylation status of the actin-binding protein cortactin upon growth factor stimulation, showing that even the activation of cortactin is time- and Src-dependent. In addition, immunofluorescence analysis with anti-paxillin antibody reveals that, after treatment with growth factors, tyrosine phosphorylated cortactin is localized on the plasma membrane in correspondence of focal adhesions. Collectively, our findings suggest a crucial role for Src-mediated activation of cortactin in cell migration, reorganization of actin cytoskeleton and phosphotyrosine cortactin localization to the focal adhesions in human breast cancer cell lines upon both IGF-1 and EGF stimulation.

Tumor cell migration in complex microenvironments

Tumor cell migration is essential for invasion and dissemination from primary solid tumors and for the establishment of lethal secondary metastases at distant organs. In vivo and in vitro models enabled identification of different factors in the tumor microenvironment that regulate tumor progression and metastasis. However, the mechanisms by which tumor cells integrate these chemical and mechanical signals from multiple sources to navigate the complex microenvironment remain poorly understood. In this review, we discuss the factors that influence tumor cell migration with a focus on the migration of transformed carcinoma cells. We provide an overview of the experimental and computational methods that allow the investigation of tumor cell migration, and we highlight the benefits and shortcomings of the various assays. We emphasize that the chemical and mechanical stimulus paradigms are not independent and that crosstalk between them motivates the development of new assays capable of applying multiple, simultaneous stimuli and imaging the cellular migratory response in real-time. These next-generation assays will more closely mimic the in vivo microenvironment to provide new insights into tumor progression, inform techniques to control tumor cell migration, and render cancer more treatable.

Overexpressed DNA-binding protein inhibitor 2 as an unfavorable prognosis factor promotes cell proliferation in nasopharyngeal carcinoma

The aim of the present study was to analyze the expression of DNA-binding protein inhibitor 2 (ID2) in nasopharyngeal carcinoma (NPC) and its correlation with clinicopathological features. It was found that the expression of ID2 was significantly increased in NPC cells when compared with that in NP69 cell line. Similar level of ID2 cytoplasmic expression was observed in NPC when compared with that in non-cancerous nasopharynx tissues. However, the level of ID2 in nucleus was increased in NPC when compared with that in normal nasopharynx tissues. Furthermore, the higher expression level of nuclear ID2 was significantly associated with tumor size (T classification), lymph node metastasis (N classification), and clinical stage. Patients with increased ID2 expression level had poorer overall survival rates than those with low ID2 levels. The inhibition of ID2 expression in NPC cell line SUNE1 by lentiviral-mediated short hairpin RNA could suppress cell proliferation and colony formation, but did not disrupt cell migration. Knocking down the expression of ID2 by RNA interference could down-regulate the expression of Snail, suggesting that ID2-promoted cell growth, partially attributing to the regulation of Snail activity in NPC. Our study demonstrated that over-expression of ID2 protein is an unfavorable prognostic factor which promotes cell proliferation in NPC.

Cigarette smoke extract stimulates epithelial-mesenchymal transition through Src activation

Epithelial-mesenchymal transition (EMT) is implicated in the pathogenesis of lung fibrosis and cancer metastasis, two conditions associated with cigarette smoke (CS). CS has been reported to promote the EMT process. CS is the major cause of lung cancer and nearly half of lung cancer patients are active smokers. Nonetheless, the mechanism whereby CS induces EMT remains largely unknown. In this study we investigated the induction of EMT by CS and explored the underlying mechanisms in the human non-small-cell lung carcinoma (H358) cell line. We demonstrate that exposure to an extract of CS (CSE) decreases E-cadherin and increases N-cadherin and vimentin, markers of EMT, in H358 cells cultured in RPMI 1640 medium with 1% fetal bovine serum. Pretreatment with N-acetylcysteine (NAC), a potent antioxidant and precursor of glutathione, abrogated changes in these EMT markers. In addition, CSE activated Src kinase (shown as increased phosphorylation of Src at Tyr418), and the Src kinase inhibitor PP2 inhibited CS-stimulated EMT changes, suggesting that Src is critical in CSE-stimulated EMT induction. Furthermore, NAC treatment abrogated CSE-stimulated Src activation. However, co-incubation with catalase had no effect on CSE-mediated Src activation. Finally, acrolein, an unsaturated aldehyde present in CSE, caused Src activation. Taken together, these data suggest that CSE initiates EMT through Src, which is activated by CS through redox modification.

MicroRNA-181a - a tale of discrepancies

MicroRNAs (miRNAs) are short noncoding RNAs that act as post-transcriptional regulators. The low complementarity required between the sequences of a miRNA and its target mRNA enables a single miRNA to act on a large range of targets. Thus miRNAs have an intersecting complex effect that spans a multiplicity of pathways and processes. In this review, the different roles of a vital miRNA, miR-181a, in physiological and pathological developments are collated in an attempt to highlight the intersections of such processes and to show how the deregulation of miR-181a could in one context drive malignancy, whereas in another it can lead to autoimmunity. Such deregulation could be related to the faulty levels of one of its own targets, p53, which was recently reported to control an array of miRNAs, one of which is miR-181a. This sheds light on a hidden loop of chaos behind chronic diseases such as autoimmunity and cancer.

Role of Src in breast cancer cell migration and invasion in a breast cell/bone-derived cell microenvironment

The preferential metastasis of breast cancer cells to bone comprises a complex set of events including homing and preferential growth, which may require unique factors produced by bone or other cells in the immediate microenvironment. In this study, an in vitro co-culture system composed of bone mesenchymal stem cells and breast cancer cell lines is used to examine the role of Src kinase on breast cancer cell migration and invasion in the presence of bone-derived cells. This research shows that Src kinase activity in breast cancer cell lines with either high or low levels of endogenous Src activity is increased by bone-derived cell-conditioned medium but not HS68 fibroblast-conditioned medium. Breast cancer cells exhibit enhanced migration in co-culture with bone-derived cells but not HS68 fibroblasts or no co-cultured cells. Inhibition of Src kinase activity using the inhibitors PP2 or saracatinib or using siRNA abrogates the preferential migration of the breast cancer cell lines in response to bone-derived cells. Inhibition of Src activity with saracatinib does not have any significant effect on breast cancer cell invasion in the presence of bone-derived cells. Factors are identified that are produced preferentially by bone-derived cells over HS68 cells that may impact breast cancer cell behavior. This research implicates Src kinase as an important effector of bone-derived cell signals on breast cancer cell migration.

Involvement of the transcription factor twist in phenotype alteration through epithelial-mesenchymal transition in lung cancer cells

Epithelial-mesenchymal transition (EMT), which involves the persistent loss of epithelial markers and expression of mesenchymal markers, is assumed to have a critical role in not only tissue development during embryogenesis but also central mechanisms that enhance the invasive and metastatic ability of cancer cells. Twist has been identified to play an essential role in EMT-mediated tumor invasion and metastasis. Although recent studies suggest that twist expression levels in tissue specimens of lung cancer might be associated with prognosis, the expression of twist in lung cancer cells itself and its effect have not been fully evaluated. Here, we evaluated twist expression and its effect on phenotype alteration in lung cancer cell lines. Twist expression varied among human lung cancer cell lines. The lung cancer cell lines with high twist expression also tended to show a high vimentin/E-cadherin ratio, which was supported by a migration assay, in which high twist expression gave rise to high cell motility. Furthermore, in comparison to control cells, the lung cancer cells with ectopic expression of twist showed a significant phenotype alteration through EMT and an increasing ability to migrate in vitro, in part, due to a tenfold increase in matrix metalloproteinases activity and almost a 60% increase in modulation of focal adhesion kinase activity, although a contribution of microRNA appeared unlikely in our study. Our present analysis of twist expression in lung cancer provide clues to comprehensive understanding of the mechanisms, by which metastasis often develops in lung cancer.