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Additional file 1: Figure S1. TRAP IL-1 blocks proliferation and clonogenicity in CTX-resistant Caco-2 cell line. Caco-2 CXR cells (1 �� 103) were seeded in 96-well plate. The next day, Caco-2 CXR cells were treated with control medium supplemented with CTX (10 ��g/ml), only medium (FM 10% FBS), and TRAP IL-1 (20 ��g/ml). After 5 days, cell viability was assessed through AlamarBlue assay. Histograms show the average of two independent experiments quintuplicated (a). To measure clonogenicity, 3 �� 103 of Caco-2 CXR were seeded in 12-well plates in triplicate and treated after 24 h as described in a and b. After 10 days, cells were fixed in 4% PFA and stained with crystal violet for 30 min. The ability of cells to grow in a colony was determined by analyzing the covered area through ImageJ software. Percentage of covered area is shown (b). Statistical analysis was carried out using one-way ANOVA and significance calculated with Tukey���s multiple comparisons test *p

Additional file 3: Figure S3. Original blots are provided.

Colorectal cancer (CRC) is the third most common cancer in the world and it is a determinant cause of mortality. A significant survival rate is achieved if the disease is detected at an early stage, thus screening represents an important cancer-control tool. Recently we unveiled a panel of mRNAs, which if isolated in whole blood represent an efficient screening test for colorectal cancer. These mRNA molecules as a biomarker in blood by qRT-PCR assay offer a test with high sensitivity and specificity for clinical diagnostics. The expression of 4 genes: TSPAN8, LGALS4, COL1A2 and CEACAM6 proved to be statistically different between patients and healthy controls. The diagnostic accuracy, in terms of specificity and sensitivity of the TSPAN8 and LGALS4 combination, displayed a sensitivity of 92.5% and a specificity of 67.2%. Our preliminary study was validated on a cohort of 134 subjects and it showed promising results for a prognostic test of blood screening. Nevertheless, it needs to be validated in a larger cohort with stage stratification and in patients with other gastrointestinal diseases.

In colorectal cancer (CRC) epidermal growth factor receptor (EGFR) family members (EGFR, HER2, HER3 and HER4) have been found frequently over-expressed. New therapies directed against EGFR have been developed in many human cancers. Unexpectedly, EGFR alterations could be good prognostic indicators, like in lung cancer, where an EGFR variant in non-smoker female patients is associated with higher survival after surgery and increases the efficiency of therapy based on EGFR inhibitors. The role of the genetic polymorphisms of the EGFR family members in colorectal cancer development has not been completely explored. In our preliminary study, three missense polymorphisms mapping in EGFR family members have been investigated in the peripheral blood of a small Italian sample size of 70 patients and 72 controls to verify if they could be considered CRC susceptibility factors. For the first time, the evidence of genotype association was found for the R521K EGFR polymorphism: the protective effect for this variant allele has been found to reduce the risk for colon cancer onset., Italian Journal of Anatomy and Embryology, Vol 116, No 1 (Supplement) 2011

Epidermal growth factor receptor (EGFR), one of the most important cell membrane receptors expressed in normal cells, is frequently overexpressed in colon cancer. EGFR is a pleiotropic signaler and the integrated biological response to EGFR activation varies from mitogenesis to apoptosis, to differentiation and to dedifferentiation even in the same cell, depending on the context. We have investigated the effect of cetuximab or gefitinib (EGFR target therapy molecules) alone and in combination with EGF, the natural ligand binding to EGFR, on human colon cancer cell lines (Caco-2 and HT-29). The aim of the study is to detect changes in gene expression profiles induced with these drug treatments, and to correlate them with the associated cell behaviors. Both drugs affect differentiation and apoptosis. HT-29 and Caco-2 displayed an important reduction of the microvilli (which also lose their erect position in Caco-2), possibly invalidating microvilli absorption function. HT-29 treated with cetuximab lost their boundary contacts and showed filipodi; on the other hand, when treated with gefitinib, they acquired cytoplasmic vesicles, and displayed reshape of the cellular membrane. Both cell lines showed a similar behavior in terms of on/off switched genes upon treatment with cetuximab. The gefitinib global gene expression pattern was different for the 2 cell lines, and directly correlated with EGF treatment. We found interesting cyto-morphological features closely related to gene expression profile. The EGFR inhibitors had a weaker effect in the presence of EGF. Our data show interesting cyto-morphological features possibly correlated to the clinical effects of cetuximab and gefitinib, and these could have implications for cancer therapy, especially as concerns the cellular microenvironment.

Anticancer therapies have been limited by the emergence of mutations and other adaptations. In bacteria, antibiotics activate the SOS response, which mobilizes error-prone factors that allow for continuous replication at the cost of mutagenesis. We investigated whether the treatment of lung cancer with EGFR inhibitors (EGFRi) similarly engages hypermutators. In cycling drug-tolerant persister (DTP) cells and in EGFRi-treated patients presenting residual disease, we observed upregulation of GAS6, whereas ablation of GAS6's receptor, AXL, eradicated resistance. Reciprocally, AXL overexpression enhanced DTP survival and accelerated the emergence of T790M, an EGFR mutation typical to resistant cells. Mechanistically, AXL induces low-fidelity DNA polymerases and activates their organizer, RAD18, by promoting neddylation. Metabolomics uncovered another hypermutator, AXL-driven activation of MYC, and increased purine synthesis that is unbalanced by pyrimidines. Aligning anti-AXL combination treatments with the transition from DTPs to resistant cells cured patient-derived xenografts. Hence, similar to bacteria, tumors tolerate therapy by engaging pharmacologically targetable endogenous mutators. Significance: EGFR-mutant lung cancers treated with kinase inhibitors often evolve resistance due to secondary mutations. We report that in similarity to the bacterial SOS response stimulated by antibiotics, endogenous mutators are activated in drug-treated cells, and this heralds tolerance. Blocking the process prevented resistance in xenograft models, which offers new treatment strategies. This article is highlighted in the In This Issue feature, p. 2483

Epidemiologic data highlight sex differences in melanoma outcome. A putative role of sex hormones is still under investigation. Very few laboratory investigations have focused on the level of expression of estrogen receptors in melanoma. We evaluated the presence of estrogen receptors alpha (ERα) and beta (ERβ) in melanoma specimens from female patients with a previous history of breast carcinoma (BC). Moreover, another group of female patients undergoing ovarian stimulation (OS) were also compared to two control groups matched for age and melanoma staging. The study was performed at the IRCCS Policlinico di Sant'Orsola Hospital's Melanoma Unit from January 2017 to December 2019. The nuclear and cytoplasmatic immunohistochemical staining was evaluated and scored by the percentage of stained tumour cells: 0 (≤20%), 1 (21-50%) or 2 (≥50%). Twenty-eight specimens were analysed. ERβ nuclear presence was detected in all cases of women with a history of breast cancer. Cytoplasmatic ERβ was clearly expressed with a score of 2 in seven cases. In the respective control group, nuclear and cytoplasmatic ERβ expression was much lower. A cytoplasmatic ERα positivity was also detected in almost all cases. In the second group of women who experienced ovarian stimulation for Assisted Reproductive Technology (ART), a lower abundance of nuclear ERs was detected. Conversely, cytoplasmatic ERβ and α expression ranged widely. Melanoma of women treated with anti-estrogen therapy is generally more prone to express estrogen receptors compared with women of the same age and CM staging but also compared with women in fertile age with and without a history of OS.

Chemotherapy and targeted therapies have significantly improved the prognosis of oncology patients. However, these antineoplastic treatments may also induce adverse cardiovascular effects, which may lead to acute or delayed onset of cardiac dysfunction. These common cardiovascular complications, commonly referred to as cardiotoxicity, not only may require the modification, suspension, or withdrawal of life-saving antineoplastic therapies, with the risk of reducing their efficacy, but can also strongly impact the quality of life and overall survival, regardless of the oncological prognosis. The onset of cardiotoxicity may depend on the class, dose, route, and duration of administration of anticancer drugs, as well as on individual risk factors. Importantly, the cardiotoxic side effects may be reversible, if cardiac function is restored upon discontinuation of the therapy, or irreversible, characterized by injury and loss of cardiac muscle cells. Subclinical myocardial dysfunction induced by anticancer therapies may also subsequently evolve in symptomatic congestive heart failure. Hence, there is an urgent need for cardioprotective therapies to reduce the clinical and subclinical cardiotoxicity onset and progression and to limit the acute or chronic manifestation of cardiac damages. In this review, we summarize the knowledge regarding the cellular and molecular mechanisms contributing to the onset of cardiotoxicity associated with common classes of chemotherapy and targeted therapy drugs. Furthermore, we describe and discuss current and potential strategies to cope with the cardiotoxic side effects as well as cardioprotective preventive approaches that may be useful to flank anticancer therapies.

Background In the last years, several efforts have been made to classify colorectal cancer (CRC) into well-defined molecular subgroups, representing the intrinsic inter-patient heterogeneity, known as Consensus Molecular Subtypes (CMSs). Methods In this work, we performed a meta-analysis of CRC patients stratified into four CMSs. We identified a negative correlation between a high level of anaplastic lymphoma kinase (ALK) expression and relapse-free survival, exclusively in CMS1 subtype. Stemming from this observation, we tested cell lines, patient-derived organoids and mice with potent ALK inhibitors, already approved for clinical use. Results ALK interception strongly inhibits cell proliferation already at nanomolar doses, specifically in CMS1 cell lines, while no effect was found in CMS2/3/4 groups. Furthermore, in vivo imaging identified a role for ALK in the dynamic formation of 3D tumor spheroids. Consistently, ALK appeares constitutively phosphorylated in CMS1, and it signals mainly through the AKT axis. Mechanistically, we found that CMS1 cells display several copies of ALKAL2 ligand and ALK-mRNAs, suggesting an autocrine loop mediated by ALKAL2 in the activation of ALK pathway, responsible for the invasive phenotype. Consequently, disruption of ALK axis mediates the pro-apoptotic action of CMS1 cell lines, both in 2D and 3D and enhanced cell-cell adhesion and e-cadherin organization. In agreement with all these findings, the ALK signature encompassing 65 genes statistically associated with worse relapse-free survival in CMS1 subtype. Finally, as a proof of concept, the efficacy of ALK inhibition was demonstrated in both patient-derived organoids and in tumor xenografts in vivo. Conclusions Collectively, these findings suggest that ALK targeting may represent an attractive therapy for CRC, and CMS classification may provide a useful tool to identify patients who could benefit from this treatment. These findings offer rationale and pharmacological strategies for the treatment of CMS1 CRC.

Prevention is essential to reduce Colorectal Cancer (CRC) mortality. We previously reported a panel of four genes: CEACAM6, LGALS4, TSPAN8, COL1A2 (CELTiC) able to discriminate patients with CRC. Here, we assessed the CELTiC panel by quantitative polymerase chain reaction, in the blood of 174 healthy subjects, who resulted negative to the faecal immunochemical test (FITN). Using non-parametric statistic and multinomial logistic models, the FITN were compared to previously analysed subjects: 36 false positive FIT (NFIT), who were negative at colonoscopy, 36 patients with low risk lesions (LR) and 92 patients with high risk lesions or CRC (HR/CRC). FITN showed a significantly lower expression of the four genes when compared to HR/CRC. Moreover, FITN showed a significantly lower expression of TSPAN8 and COL1A2 compared to NFIT and LR patients. The multinomial logistic model confirmed that TSPAN8 alone specifically discriminated FITN from NFIT, LR and HR/CRC, while LGALS4 was able to differentiate FITN from false positive FIT. Finally, ROC curves analysis of the comparisons between FITN and HR/CRC, LR or NFIT reported AUC greater than 0.87, with a sensitivity and specificity of 83% and 76%, respectively. The CELTiC panel was confirmed a useful tool to identify CRC patients and to discriminate false FIT positive subjects.

Crosstalk between growth factors (GFs) and steroid hormones recurs in embryogenesis and is co-opted in pathology, but underlying mechanisms remain elusive. Our data from mammary cells imply that the crosstalk between the epidermal GF and glucocorticoids (GCs) involves transcription factors like p53 and NF-κB, along with reduced pausing and traveling of RNA polymerase II (RNAPII) at both promoters and bodies of GF-inducible genes. Essentially, GCs inhibit positive feedback loops activated by GFs and stimulate the reciprocal inhibitory loops. As expected, no alterations in DNA methylation accompany the transcriptional events instigated by either stimulus, but forced demethylation of regulatory regions broadened the repertoire of GF-inducible genes. We report that enhancers, like some promoters, are poised for activation by GFs and GCs. In addition, within the cooperative interface of the crosstalk, GFs enhance binding of the GC receptor to DNA and, in synergy with GCs, promote productive RNAPII elongation. Reciprocally, within the antagonistic interface GFs hyper-acetylate chromatin at unmethylated promoters and enhancers of genes involved in motility, but GCs hypoacetylate the corresponding regions. In conclusion, unmethylated genomic regions that encode feedback regulatory modules and differentially recruit RNAPII and acetylases/deacetylases underlie the crosstalk between GFs and a steroid hormone.

During the past three decades, epidermal growth factor receptor (EGFR) targeting has been intensely pursued as a treatment strategy for metastatic colorectal cancer. One approach uses monoclonal antibodies to inhibit the extracellular domain of EGFR, thus blocking natural ligands binding. Unfortunately, patients often develop resistance, with consequent growth of tumor burden and relapse. This chapter discusses some of the mechanisms responsible for the failure of current therapies. Tumor heterogeneity is addressed as the main culprit for multiple escaping mechanisms, reflecting the high level of molecular heterogeneity present in each metastatic site. Genetic as well as nongenetic mechanisms are discussed, including acquisition of activating mutations in the mitogen-activated protein kinase axis mediators, epithelial-to-mesenchymal transition, activation of EGFR feedback loops, and signaling reactivation and bypass. Finally, autocrine and microenvironment secretion of growth factors that aid proliferative and anti-apoptotic signaling are also reported. The chapter concludes with an introduction of some promising combinatorial approaches, developed to overcome resistance to EGFR blockage.

// Valerio Gelfo 1, 2, * , Maria Teresa Rodia 1, * , Michela Pucci 1 , Massimiliano Dall’Ora 1 , Spartaco Santi 3, 4 , Rossella Solmi 1 , Lee Roth 5 , Moshit Lindzen 5 , Massimiliano Bonafe 1, 2 , Andrea Bertotti 6 , Elisabetta Caramelli 1 , Pier-Luigi Lollini 1 , Livio Trusolino 6 , Yosef Yarden 5 , Gabriele D’Uva 7, ** , Mattia Lauriola 1, 2, ** 1 Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna, Bologna, Italy 2 Center for Applied Biomedical Research (CRBA) S. Orsola-Malpighi University Hospital, University of Bologna, Bologna, Italy 3 Institute of Molecular Genetics, National Research Council of Italy, Bologna, Italy 4 Laboratory of Musculoskeletal Cell Biology, IOR-IRCCS, Bologna, Italy 5 Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel 6 Candiolo Cancer Institute-Fondazione del Piemonte per l’Oncologia (FPO), IRCCS, Department of Oncology, University of Torino, Candiolo, Italy 7 Scientific and Technology Pole, IRCCS MultiMedica, Milan, Italy * These authors have contributed equally to this work ** Co-last authors Correspondence to: Mattia Lauriola, email: mattia.lauriola@gmail.com Keywords: EGFR, transcriptional response, colon cancer, resistance, cetuximab Received: June 13, 2016 Accepted: September 21, 2016 Published: September 30, 2016 ABSTRACT Epidermal Growth Factor Receptor (EGFR) activates a robust signalling network to which colon cancer tumours often become addicted. Cetuximab, one of the monoclonal antibodies targeting this pathway, is employed to treat patients with colorectal cancer. However, many patients are intrinsically refractory to this treatment, and those who respond develop secondary resistance along time. Mechanisms of cancer cell resistance include either acquisition of new mutations or non genomic activation of alternative signalling routes. In this study, we employed a colon cancer model to assess potential mechanisms driving resistance to cetuximab. Resistant cells displayed increased ability to grow in suspension as colonspheres and this phenotype was associated with poorly organized structures. Factors secreted from resistant cells were causally involved in sustaining resistance, indeed administration to parental cells of conditioned medium collected from resistant cells was sufficient to reduce cetuximab efficacy. Among secreted factors, we report herein that a signature of inflammatory cytokines, including IL1A , IL1B and IL8 , which are produced following EGFR pathway activation, was associated with the acquisition of an unresponsive phenotype to cetuximab in vitro . This signature correlated with lack of response to EGFR targeting also in patient-derived tumour xenografts. Collectively, these results highlight the contribution of inflammatory cytokines to reduced sensitivity to EGFR blockade and suggest that inhibition of this panel of cytokines in combination with cetuximab might yield an effective treatment strategy for CRC patients refractory to anti-EGFR targeting.

Circular RNAs (circRNAs) are widespread circles of non-coding RNAs with largely unknown function. Because stimulation of mammary cells with the epidermal growth factor (EGF) leads to dynamic changes in the abundance of coding and non-coding RNA molecules, and culminates in the acquisition of a robust migratory phenotype, this cellular model might disclose functions of circRNAs. Here we show that circRNAs of EGF-stimulated mammary cells are stably expressed, while mRNAs and microRNAs change within minutes. In general, the circRNAs we detected are relatively long-lived and weakly expressed. Interestingly, they are almost ubiquitously co-expressed with the corresponding linear transcripts, and the respective, shared promoter regions are more active compared to genes producing linear isoforms with no detectable circRNAs. These findings imply that altered abundance of circRNAs, unlike changes in the levels of other RNAs, might not play critical roles in signaling cascades and downstream transcriptional networks that rapidly commit cells to specific outcomes.

Trisomy 21 causes Down syndrome (DS), the most common human genetic disorder and the leading genetic cause of intellectual disability. The alteration of one-carbon metabolism was described as the possible metabolic cause of the intellectual disability development in subjects with DS. One of the biochemical pathways involved in the one-carbon group transfer is the folate cycle. The cytotoxic drug methotrexate (MTX) is a folic acid (FA) analogue which inhibits the activity of dihydrofolate reductase enzyme involved in the one-carbon metabolic cycle. Trisomy 21 cells are more sensitive to the MTX effect than euploid cells, and in 1986 Jerome Lejeune and Coll. demonstrated that MTX was twice as toxic in trisomy 21 lymphocytes than in control cells. In the present work, the rescue effect on MTX toxicity mediated by FA and some of its derivatives, tetrahydrofolate (THF), 5-formyl-THF, and 5-methyl-THF, in both normal and trisomy 21 skin fibroblast cells, was evaluated. A statistically significant rescue effect was obtained by 5-formyl-THF, 5-methyl-THF, and their combination, administered together with MTX. In conclusion, trisomy 21 fibroblast cell lines showed a good response to the rescue effects of 5-formyl-THF and 5-methyl-THF on the MTX toxicity almost as normal cell lines.

Mutations mimicking growth factor–induced proliferation and motility characterize aggressive subtypes of mammary tumors. To unravel currently unknown players in these processes, we performed phosphoproteomic analysis on untransformed mammary epithelial cells (MCF10A) that were stimulated in culture with epidermal growth factor (EGF). We identified ladinin-1 (LAD1), a largely uncharacterized protein to date, as a phosphorylation-regulated mediator of the EGF-to-ERK pathway. Further experiments revealed that LAD1 mediated the proliferation and migration of mammary cells. LAD1 was transcriptionally induced, phosphorylated, and partly colocalized with actin stress fibers in response to EGF. Yeast two-hybrid, proximity ligation, and coimmunoprecipitation assays revealed that LAD1 bound to actin–cross-linking proteins called filamins. Cosedimentation analyses indicated that LAD1 played a role in actin dynamics, probably in collaboration with the scaffold protein 14-3-3 (also called SFN). Depletion of LAD1 decreased the expression of transcripts associated with cell survival and inhibited the growth of mammary xenografts in an animal model. Furthermore, LAD1 predicts poor patient prognosis and is highly expressed in aggressive subtypes of breast cancer characterized as integrative clusters 5 and 10, which partly correspond to triple-negative and HER2-positive tumors. Thus, these findings reveal a cytoskeletal component that is critically involved in cell migration and the acquisition of oncogenic attributes in human mammary tumors.

Background A noninvasive blood test for the early detection of colorectal cancer (CRC) is highly required. We evaluated a panel of 4 mRNAs as putative markers of CRC. Materials and Methods We tested LGALS4, CEACAM6, TSPAN8, and COL1A2, referred to as the CELTiC panel, using quantitative reverse transcription polymerase chain reaction, on subjects with positive fecal immunochemical test (FIT) results and undergoing colonoscopy. Using a nonparametric test and multinomial logistic model, FIT-positive subjects were compared with CRC patients and healthy individuals. Results All the genes of the CELTiC panel displayed statistically significant differences between the healthy subjects (n = 67), both low-risk (n = 36) and high-risk/CRC (n = 92) subjects, and those in the negative-colonoscopy, FIT-positive group (n = 36). The multinomial logistic model revealed LGALS4 was the most powerful marker discriminating the 4 groups. When assessing the diagnostic values by analysis of the areas under the receiver operating characteristic curves (AUCs), the CELTiC panel reached an AUC of 0.91 (sensitivity, 79%; specificity, 94%) comparing normal subjects to low-risk subjects, and 0.88 (sensitivity, 75%; specificity, 87%) comparing normal and high-risk/CRC subjects. The comparison between the normal subjects and the negative-colonoscopy, FIT-positive group revealed an AUC of 0.93 (sensitivity, 82%; specificity, 97%). Conclusion The CELTiC panel could represent a useful tool for discriminating subjects with positive FIT findings and for the early detection of precancerous adenomatous lesions and CRC.

In the last three decades cutaneous melanoma has been widely investigated as a steroid hormone-sensitive cancer. Following this hypothesis, many epidemiological studies have investigated the relationship between estrogens and melanoma. No evidence to date has supported this association due to the great complexity of genetic, external and environmental factors underlying the development of this cancer. Molecular mechanisms through which estrogen and their receptor exert a role in melanoma genesis are still under investigation with new studies increasingly focusing on the discovery of new molecular targets for therapeutic treatments.

Evidences of a crosstalk between Epidermal Growth Factor Receptor (EGFR) and Glucocorticoid Receptor (GR) has been reported, ranging from the modulation of receptor levels or GR mediated transcriptional repression of EGFR target genes, with modifications of epigenetic markers. The present study focuses on the involvement of EGFR positive and negative feedback genes in the establishment of cetuximab (CTX) resistance in metastatic Colorectal Cancer (CRC) patients. We evaluated the expression profile of the EGFR ligands TGFA and HBEGF, along with the pro-inflammatory cytokines IL-1B and IL-8, which were previously reported to be negatively associated with monoclonal antibody response, both in mice and patient specimens. Among EGFR negative feedback loops, we focused on ERRFI1, DUSP1, LRIG3, and LRIG1. We observed that EGFR positive feedback genes are increased in CTX-resistant cells, whereas negative feedback genes are reduced. Next, we tested the expression of these genes in CTX-resistant cells upon GR modulation. We unveiled that GR activation leads to an increase in ERRFI1, DUSP1, and LRIG1, which were shown to restrict EGFR activity, along with a decrease in the EGFR activators (TGFA and IL-8). Finally, in a cohort of xenopatients, stratified for response to cetuximab, we observed an inverse association between the expression level of LRIG1 and CRC progression upon CTX treatment. Our model implies that combining GR modulation to EGFR inhibition may yield an effective treatment strategy in halting cancer progression.

Growth factors acting through receptor tyrosine kinases (RTKs) of ERBB family, along with steroid hormones (SH) acting through nuclear receptors (NRs), are critical signalling mediators of cellular processes. Deregulations of ERBB and steroid hormone receptors are responsible for several diseases, including cancer, thus demonstrating the central role played by both systems. This review will summarize and shed light on an emerging crosstalk between these two important receptor families. How this mutual crosstalk is attained, such as through extensive genomic and non-genomic interactions, will be addressed. In light of recent studies, we will describe how steroid hormones are able to fine-tune ERBB feedback loops, thus impacting on cellular output and providing a new key for understanding the complexity of biological processes in physiological or pathological conditions. In our understanding, the interactions between steroid hormones and RTKs deserve further attention. A system biology approach and advanced technologies for the analysis of RTK-SH crosstalk could lead to major advancements in molecular medicine, providing the basis for new routes of pharmacological intervention in several diseases, including cancer.

Growth factors promote tumor growth and metastasis. We found that epidermal growth factor (EGF) induced a set of 22 microRNAs (miRNAs) before promoting the migration of mammary cells. These miRNAs were more abundant in human breast tumors relative to the surrounding tissue, and their abundance varied among breast cancer subtypes. One of these miRNAs, miR-15b, targeted the 3' untranslated region of MTSS1 (metastasis suppressor protein 1). Although xenografts in which MTSS1 was knocked down grew more slowly in mice initially, longer-term growth was unaffected. Knocking down MTSS1 increased migration and Matrigel invasion of nontransformed mammary epithelial cells. Overexpressing MTSS1 in an invasive cell line decreased cell migration and invasiveness, decreased the formation of invadopodia and actin stress fibers, and increased the formation of cellular junctions. In tissues from breast cancer patients with the aggressive basal subtype, an inverse correlation occurred with the high expression of miRNA-15b and the low expression of MTSS1. Furthermore, low abundance of MTSS1 correlated with poor patient prognosis. Thus, growth factor-inducible miRNAs mediate mechanisms underlying the progression of cancer.

Amplified HER2, which encodes a member of the epidermal growth factor receptor (EGFR) family, is a target of effective therapies against breast cancer. In search for similarly targetable genomic aberrations, we identified copy number gains in SYNJ2, which encodes the 5'-inositol lipid phosphatase synaptojanin 2, as well as overexpression in a small fraction of human breast tumors. Copy gain and overexpression correlated with shorter patient survival and a low abundance of the tumor suppressor microRNA miR-31. SYNJ2 promoted cell migration and invasion in culture and lung metastasis of breast tumor xenografts in mice. Knocking down SYNJ2 impaired the endocytic recycling of EGFR and the formation of cellular lamellipodia and invadopodia. Screening compound libraries identified SYNJ2-specific inhibitors that prevented cell migration but did not affect the related neural protein SYNJ1, suggesting that SYNJ2 is a potentially druggable target to block cancer cell migration.