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© 2021 The Authors., Cancer stem cells (CSC) are considered responsible for tumor initiation, therapeutic resistance, and metastasis. A comprehensive knowledge of the mechanisms governing the acquisition and maintenance of cancer stemness is crucial for the development of new therapeutic approaches in oncology. E2A basic helix–loop–helix (bHLH) transcription factors are associated with epithelial–mesenchymal transition (EMT) and tumor progression, but knowledge of their functional contributions to cancer biology is still limited. Using a combination of in vivo and in vitro analyses in a novel PyMT-E2A conditional knockout mouse model and derived primary tumor cell lines, we report here an essential role of E2A in stemness, metastasis, and therapeutic resistance in breast cancer. Targeted deletion of E2A in the mammary gland impaired tumor-initiating ability and dedifferentiation potential and severely compromised metastatic competence of PyMT-driven mammary tumors. Mechanistic studies in PyMT-derived cell lines indicated that E2A actions are mediated by the upregulation of Snai1 transcription. Importantly, high E2A and SNAIL1 expression occurred in aggressive human basal-like breast carcinomas, highlighting the relevance of the E2A–Snail1 axis in metastatic breast cancer. In addition, E2A factors contributed to the maintenance of genomic integrity and resistance to PARP inhibitors in PyMT and human triple-negative breast cancer cells. Collectively, these results support the potential for E2A transcription factors as novel targets worthy of translational consideration in breast cancer., This work has been supported by grants from the Spanish Ministry of Economy and Innovation (SAF2013–44739-R, SAF2016–76504-R to A. Cano and F. Portillo), PID2019–111052RB-I00 to F. Portillo, PID2019–104644RB-I00 to G. Moreno-Bueno; the Spanish Institute of Health Carlos III (CIBERONC-CB16/12/00295 to A. Cano, G. Moreno-Bueno; all of them partly supported by FEDER funds); the AECC Scientific Foundation 2019 (PROYE19036MOR to G. Moreno-Bueno); the Association International for Cancer Research (AICR; 12–1057 to A. Cano, P.G. Santamaría); and Worldwide Cancer Research (16–0295 to A. Cano, F. Portillo, and P.G. Santamaría). A. Vázquez-Naharro was funded by a PhD contract from SAF2016–76504-R grant; V. Santos by AICR (12–1057) and SAF2016–76504-R grants; P.G. Santamaría by a research contract of the AECC Scientific Foundation, and from Worldwide Cancer Research (16–0295) and SAF2016–76504-R grants.

Background In recent years, the identification of genetic and phenotypic biomarkers of cancer for prevention, early diagnosis and patient stratification has been a main objective of research in the field. Different multivariable models that use biomarkers have been proposed for the evaluation of individual risk of developing breast cancer. Methods This is a case control study based on a population-based cohort. We describe and evaluate a multivariable model that incorporates 92 Single-nucleotide polymorphisms (SNPs) (Supplementary Table S1) and five different phenotypic variables and which was employed in a Spanish population of 642 healthy women and 455 breast cancer patients. Results Our model allowed us to stratify two groups: high and low risk of developing breast cancer. The 9th decile included 1% of controls vs 9% of cases, with an odds ratio (OR) of 12.9 and a p-value of 3.43E-07. The first decile presented an inverse proportion: 1% of cases and 9% of controls, with an OR of 0.097 and a p-value of 1.86E-08. Conclusions These results indicate the capacity of our multivariable model to stratify women according to their risk of developing breast cancer. The major limitation of our analysis is the small cohort size. However, despite the limitations, the results of our analysis provide proof of concept in a poorly studied population, and opens up the possibility of using this method in the routine screening of the Spanish population.

On behalf of the EMT International Association (TEMTIA)., Epithelial–mesenchymal transition (EMT) encompasses dynamic changes in cellular organization from epithelial to mesenchymal phenotypes, which leads to functional changes in cell migration and invasion. EMT occurs in a diverse range of physiological and pathological conditions and is driven by a conserved set of inducing signals, transcriptional regulators and downstream effectors. With over 5,700 publications indexed by Web of Science in 2019 alone, research on EMT is expanding rapidly. This growing interest warrants the need for a consensus among researchers when referring to and undertaking research on EMT. This Consensus Statement, mediated by ‘the EMT International Association’ (TEMTIA), is the outcome of a 2-year-long discussion among EMT researchers and aims to both clarify the nomenclature and provide definitions and guidelines for EMT research in future publications. We trust that these guidelines will help to reduce misunderstanding and misinterpretation of research data generated in various experimental models and to promote cross-disciplinary collaboration to identify and address key open questions in this research field. While recognizing the importance of maintaining diversity in experimental approaches and conceptual frameworks, we emphasize that lasting contributions of EMT research to increasing our understanding of developmental processes and combatting cancer and other diseases depend on the adoption of a unified terminology to describe EMT.

Traditionally, studies to address the characterization of mechanisms promoting tumor aggressiveness and progression have been focused only on primary tumor analyses, which could provide relevant information but have limitations to really characterize the more aggressive tumor population. To overcome these limitations, circulating tumor cells (CTCs) represent a noninvasive and valuable tool for real-time profiling of disseminated tumor cells. Therefore, the aim of the present study was to explore the value of CTC enumeration and characterization to identify markers associated with the outcome and the aggressiveness of triple-negative breast cancer (TNBC). For that aim, the CTC population from 32 patients diagnosed with TNBC was isolated and characterized. This population showed important cell plasticity in terms of expression of epithelia/mesenchymal and stemness markers, suggesting the relevance of epithelial to mesenchymal transition (EMT) intermediate phenotypes for efficient tumor dissemination. Importantly, the CTC signature demonstrated prognostic value to predict the patients&rsquo, outcome and pointed to a relevant role of tissue inhibitor of metalloproteinases 1 (TIMP1) and androgen receptor (AR) for TNBC biology. Furthermore, we also analyzed the usefulness of the AR and TIMP1 blockade to target TNBC proliferation and dissemination using in vitro and in vivo zebra fish and mouse models. Overall, the molecular characterization of CTCs from advanced TNBC patients identifies highly specific biomarkers with potential applicability as noninvasive prognostic markers and reinforced the value of TIMP1 and AR as potential therapeutic targets to tackle the most aggressive breast cancer.

Therapy resistance is responsible for tumour recurrence and represents one of the major challenges in present oncology. Significant advances have been made in the understanding of the mechanisms underlying resistance to conventional and targeted therapies improving the clinical management of relapsed patients. Unfortunately, in too many cases, resistance reappears leading to a fatal outcome. The recent introduction of immunotherapy regimes has provided an unprecedented success in the treatment of specific cancer types; however, a good percentage of patients do not respond to immune-based treatments or ultimately become resistant. Cellular plasticity, cancer cell stemness and tumour heterogeneity have emerged as important determinants of treatment resistance. Epithelial-to-mesenchymal transition (EMT) is associated with resistance in many di erent cellular and preclinical models, although little evidence derives directly from clinical samples. The recognition of the presence in tumours of intermediate hybrid epithelial/mesenchymal states as the most likely manifestation of epithelial plasticity and their potential link to stemness and tumour heterogeneity, provide new clues to understanding resistance and could be exploited in the search for anti-resistance strategies. Here, recent evidence linking EMT/epithelial plasticity to resistance against conventional, targeted and immune therapy are summarized. In addition, future perspectives for related clinical approaches are also discussed, This work was supported by grants from the Spanish Ministerio de Economía y Competividad (SAF2013-44739-R, SAF2016-76504-R) and Instituto de Salud Carlos III (CIBERONC 16/12/00295; PI16/00134), all of them partly supported by EU-FEDER fund, FC AECC (Grupos Estables de Investigación 2018-AECC) and Worldwide Cancer Research UK (formerly AICR, 12-1057 and 16-0295)

Lysyl oxidase-like 3 (LOXL3) is a member of the lysyl oxidase family comprising multifunctional enzymes with depicted roles in extracellular matrix maturation, tumorigenesis, and metastasis. In silico expression analyses followed by experimental validation in a comprehensive cohort of human cell lines revealed a significant upregulation of LOXL3 in human melanoma. We show that LOXL3 silencing impairs cell proliferation and triggers apoptosis in various melanoma cell lines. Further supporting a pro-oncogenic role in melanoma, LOXL3 favors tumor growth in vivo and cooperates with oncogenic BRAF in melanocyte transformation. Upon LOXL3 depletion, melanoma cells display a faulty DNA damage response (DDR), characterized by ATM checkpoint activation and inefficient ATR activation leading to the accumulation of double-strand breaks (DSBs) and aberrant mitosis. Consistent with these findings, LOXL3 binds to proteins involved in the maintenance of genome integrity, in particular BRCA2 and MSH2, whose levels dramatically decrease upon LOXL3 depletion. Moreover, LOXL3 is required for efficient DSB repair in melanoma cells. Our results reveal an unexpected role for LOXL3 in the control of genome stability and melanoma progression, exposing its potential as a novel therapeutic target in malignant melanoma, a very aggressive condition yet in need for more effective treatment options., A.F.M. was supported by a FPI predoctoral fellowship from the Spanish Ministry of Economy and Innovation (MINECO) (associated to SAF2013-44739-R) and by Worldwide Cancer Research (16–0295) grant. P.G.S. was a recipient of an Oncology Research Contract (AIO) from the Fundación de la Asociación Española contra el Cáncer (AECC) and is currently funded by Worldwide Cancer Research (16–0295) grant. A.V-N., V.S., S.M., and L.Y. were supported by AICR, MINECO and the Spanish Fondo de Investigaciones Sanitarias (FIS). E.H.'s laboratory is funded by the NIH (US) (R01CA155234, R01CA163891, and R21AR062239). Work in the A.C.'s laboratory is supported by grants from the MINECO (SAF2013-44739-R, SAF2016-76504-R, ConsoliderIngenio ONCOBIO CSD00C-2007-00017), Comunidad de Madrid (S2010/BMD-2303), ISCIII (RTICC-RD12/0036/0007, CIBERONCCB16/12/00295), all of them partly supported from EU-FEDER funds, and Worldwide Cancer Research UK (formerly AICR, 12-1057, and 16-0295 grants).

Summary Lysyl-oxidase-like 2 (LOXL2) is a member of the lysyl oxidase family that catalyzes the cross-linking of collagens or elastins in the extracellular matrix, thus regulating the tensile strength of tissues. However, many reports have suggested different intracellular roles for LOXL2, including the ability to regulate gene transcription and tumor progression. We previously reported that LOXL2 mediates epithelial-to-mesenchymal transition (EMT) by Snail1-dependent and independent mechanisms, related to E-cadherin silencing and downregulation of epidermal differentiation and cell polarity components, respectively. Whether or not the catalytic activity of LOXL2 is required to induce/sustain EMT is actually unknown. Here we show that LOXL2 catalytic inactive mutants collaborate with Snail1 in E-cadherin gene repression to trigger EMT and, in addition, promote FAK/Src pathway activation to support EMT. These findings reveal a non-conventional role of LOXL2 on regulating epithelial cell plasticity.

The lysyl oxidase-like protein LOXL2 has been suggested to contribute to tumor progression and metastasis, but in vivo evidence has been lacking. Here we provide functional evidence that LOXL2 is a key driver of breast cancer metastasis in two conditional transgenic mouse models of PyMT-induced breast cancer. LOXL2 ablation in mammary tumor cells dramatically decreased lung metastasis, whereas LOXL2 overexpression promoted metastatic tumor growth. LOXL2 depletion or overexpression in tumor cells does not affect extracellular matrix stiffness or organization in primary and metastatic tumors, implying a function for LOXL2 independent of its conventional role in extracellular matrix remodeling. In support of this likelihood, cellular and molecular analyses revealed an association of LOXL2 action with elevated levels of the EMT regulatory transcription factor Snail1 and expression of several cytokines that promote premetastatic niche formation. Taken together, our findings established a pathophysiologic role and new function for LOXL2 in breast cancer metastasis., This work has been supported by grants from the Spanish Ministry of Economy and Innovation SAF2010-21143 (to A. Cano, F. Portillo), SAF2013-44739-R (to A. Cano, P.G. Santamaría, F. Portillo), SAF2016-76504-R (to A. Cano, C. Lopez-Menendez, P.G. Santamaría, F. Portillo), and CONSOLIDER-INGENIO 2010 CSD2007-00017 (to A. Cano), the Spanish Instituto de Salud Carlos III [(RETIC-RD12/0036/0007 to A. Cano, G. Moreno-Bueno, P.G. Santamaria, F. Portillo and CIBERONC to A. Cano, G. Moreno-Bueno, F. Portillo, R. Lopez-Lopez, L. Muinelo-Romay, PI13/00132 to G. Moreno-Bueno (all partly supported by FEDER funds)]; Worldwide Cancer Research (formerly AICR) 12-1057 to A. Cano, A. Martin, P.G. Santamaría; Worldwide Cancer Research 16-0295 to A. Cano, F. Portillo, P.G. Santamaría; Comunidad de Madrid (S2010/BMD-2303 to A. Cano, G. Moreno-Bueno); AECC-2011 to G. Moreno-Bueno; and TV3-Telemarato 2013 to G. Moreno-Bueno. A. Martin, F. Salvador, and A. Vazquez-Naharro were funded by the JAE-CSIC program, S2010/BMD-2303, SAF2013-44739-R, and Worldwide Cancer Research 12-1057 grants; P.G. Santamaría by a contract from Fundacion AECC (Spain) and, presently, by Worldwide Cancer Research 16-0295 grant; V. Santos by CSD2007-00017, Worldwide Cancer Research 12-1057 and SAF2013-44739-R grants, and S. Morales by RETIC-RD12/0036/0007 grant.

Lysyl oxidase-like 2 (LOXL2) is involved in a wide range of physiological and pathological processes, including fibrosis and tumor progression, implicating intracellular and extracellular functions. To explore the specific in vivo role of LOXL2 in physiological and tumor contexts, we generated conditional gain- and loss-of-function mouse models. Germ-line deletion of Loxl2 promotes lethality in half of newborn mice mainly associated to congenital heart defects, while Loxl2 overexpression triggers male sterility due to epididymal dysfunction caused by epithelial disorganization, fibrosis and acute inflammation. Remarkably, when challenged to chemical skin carcinogenesis, Loxl2-overexpressing mice increased tumor burden and malignant progression, while Loxl2-deficient mice exhibit the opposite phenotypes. Loxl2 levels in premalignant tumors negatively correlate with expression of epidermal differentiation markers and components of the Notch1 pathway. We show that LOXL2 is a direct repressor of NOTCH1. Additionally, we identify an exclusive expression pattern between LOXL2 and members of the canonical NOTCH1 pathway in human HNSCC. Our data identify for the first time novel LOXL2 roles in tissue homeostasis and support it as a target for SCC therapy., This work has been supported by grants from the Spanish Ministry of Economy and Innovation SAF2010-21143 (AC), SAF2010-20175 (GMB), SAF2013-44739-R (AC and FP) and CONSOLIDER-INGENIO 2010 CSD2007-00017 (AC); the AICR (12-1057) (AC and AM), the Spanish Instituto de Salud Carlos III [(RETIC-RD12/0036/0007 (AC), RETICC-RD12/0036/0054 (AB), PI13/00132 (GMB)], Comunidad de Madrid (S2010/BMD-2303) (AC and GMB) and AECC-2011 (GMB). AM and EPC are founded by postdoctoral contracts from S2010/BMD-2303 and AICR grants, respectively; FS was founded by a Jae-pre contract from the CSIC; and SM and VS are founded by technician contracts from the RETIC-RD12/0036/0007 and AICR grants, respectively.

This is an open-access article distributed under the terms of the Creative Commons Attribution License.-- et al., Gasdermin B (GSDMB) belongs to the Gasdermin protein family that comprises four members (GSDMA-D). Gasdermin B expression has been detected in some tumor types such as hepatocarcinomas, gastric and cervix cancers; and its overexpression has been related to tumor progression. At least four splicing isoforms of GSDMB have been identified, which may play differential roles in cancer. However, the implication of GSDMB in carcinogenesis and tumor progression is not well understood. Here, we uncover for the first time the functional implication of GSDMB in breast cancer. Our data shows that high levels of GSDMB expression is correlated with reduced survival and increased metastasis in breast cancer patients included in an expression dataset (>1,000 cases). We demonstrate that GSDMB is upregulated in breast carcinomas compared to normal breast tissue, being the isoform 2 (GSDMB-2) the most differentially expressed. In order to evaluate the functional role of GSDMB in breast cancer two GSDMB isoforms were studied (GSDMB-1 and GSDMB-2). The overexpression of both isoforms in the MCF7 breast carcinoma cell line promotes cell motility and invasion, while its silencing in HCC1954 breast carcinoma cells decreases the migratory and invasive phenotype. Importantly, we demonstrate that both isoforms have a differential role on the activation of Rac-1 and Cdc-42 Rho-GTPases. Moreover, our data support that GSMDB-2 induces a pro-tumorigenic and pro-metastatic behavior in mouse xenograft models as compared to GSDMB-1. Finally, we observed that although both GSDMB isoforms interact in vitro with the chaperone Hsp90, only the GSDMB-2 isoform relies on this chaperone for its stability. Taken together, our results provide for the first time evidences that GSDMB-2 induces invasion, tumor progression and metastasis in MCF7 cells and that GSDMB can be considered as a new potential prognostic marker in breast cancer., This work was supported by grants from the Spanish Ministry of Science and Innovation, MICINN (SAF2007-63075 and SAF2010-20175), AVON Foundation 2012, Comunidad de Madrid (S2010/BMD-2302), AECC network 2011, Instituto de Salud Carlos III (ISCIII) (PI13_00132) to GMB and Breast Network from ISCIII RD12036/0007 to AC. MHR has been funded by a predoctoral contract associated to SAF2007-63075 and now has a postdoc contract from S2010/BMD-23. DS and PGS are funded by postdoc contracts from the AECC Scientific Foundation, AM is funded by a predoctoral fellowship from MECD; ACM is funded by ISCIII RD12036/0007. Dr HP’s work is supported by the Melanoma Research Alliance, Pediatric Oncology Experimental Therapeutics Investigators Consortium, The Nancy C. and Daniel P. Paduano Foundation, The Manning Foundation, NCI (U01 CA169538, RO1 CA169416-01) and the DoD (BC123187, BC121988).

This is an Open Access article distributed under the terms of the Creative Commons Attribution License.-- et al., [Background]: About 20% of patients diagnosed with endometrial cancer (EC) are considered high-risk with unfavorable prognosis. In the framework of the European Network for Individualized Treatment in EC (ENITEC), we investigated the presence and phenotypic features of Circulating Tumor Cells (CTC) in high-risk EC patients. [Methods]: CTC isolation was carried out in peripheral blood samples from 34 patients, ranging from Grade 3 Stage IB to Stage IV carcinomas and recurrences, and 27 healthy controls using two methodologies. Samples were subjected to EpCAM-based immunoisolation using the CELLection™ Epithelial Enrich kit (Invitrogen, Dynal) followed by RTqPCR analysis. The phenotypic determinants of endometrial CTC in terms of pathogenesis, hormone receptor pathways, stem cell markers and epithelial to mesenchymal transition (EMT) drivers were asked. Kruskal-Wallis analysis followed by Dunn's post-test was used for comparisons between groups. Statistical significance was set at p < 0.05. [Results]: EpCAM-based immunoisolation positively detected CTC in high-risk endometrial cancer patients. CTC characterization indicated a remarkable plasticity phenotype defined by the expression of the EMT markers ETV5, NOTCH1, SNAI1, TGFB1, ZEB1 and ZEB2. In addition, the expression of ALDH and CD44 pointed to an association with stemness, while the expression of CTNNB1, STS, GDF15, RELA, RUNX1, BRAF and PIK3CA suggested potential therapeutic targets. We further recapitulated the EMT phenotype found in endometrial CTC through the up-regulation of ETV5 in an EC cell line, and validated in an animal model of systemic dissemination the propensity of these CTC in the accomplishment of metastasis. [Conclusions]: Our results associate the presence of CTC with high-risk EC. Gene-expression profiling characterized a CTC-plasticity phenotype with stemness and EMT features. We finally recapitulated this CTC-phenotype by over-expressing ETV5 in the EC cell line Hec1A and demonstrated an advantage in the promotion of metastasis in an in vivo mouse model of CTC dissemination and homing., ISCIII PI11/00873; Fundación Asociación Española Contra el Cancer (AECC), Grupos Estables 2011; InveNNta (Innovation in Nanomedicine), co-financed by the European Union (EU) through the Operational Programme for Cross-border Cooperation, Spain-Portugal (POCTEP 2007-2013), European Regional Development Fund (ERDF); Helse Vest, Research Council of Norway, Norwegian Cancer Society and Harald Andersens legat (H.B.S.); L. Alonso-Alconada is recipient of fellowship from the Basque Government (Spain).

Snail1 and Snail2, two highly related members of the Snail superfamily, are direct transcriptional repressors of E-cadherin and EMT inducers. Previous comparative gene profiling analyses have revealed important differences in the gene expression pattern regulated by Snail1 and Snail2, indicating functional differences between both factors. The molecular mechanism of Snail1-mediated repression has been elucidated to some extent, but very little is presently known on the repression mediated by Snail2. In the present work, we report on the characterization of Snail2 repression of E-cadherin and its regulation by phosphorylation. Both the N-terminal SNAG and the central SLUG domains of Snail2 are required for efficient repression of the E-cadherin promoter. The co-repressor NCoR interacts with Snail2 through the SNAG domain, while CtBP1 is recruited through the SLUG domain. Interestingly, the SNAG domain is absolutely required for EMT induction while the SLUG domain plays a negative modulation of Snail2 mediated EMT. Additionally, we identify here novel in vivo phosphorylation sites at serine 4 and serine 88 of Snail2 and demonstrate the functional implication of serine 4 in the regulation of Snail2-mediated repressor activity of E-cadherin and in Snail2 induction of EMT. © 2012 Molina-Ortiz et al., This work was supported by the EU-FP6 (RTN-Epiplast Carcinoma, MRTN-CT-2004-005428), the Spanish Ministry of Science and Innovation (SAF2007- 06351, SAF2010-21143, Consolider Ingenio CDS2007-00017) and Fundación Mutua Madrileña (FMM2009) to AC. During the realization of this work MMcP was supported by the EU Marie Curie program and PMO was supported by a FPI fellowship from the Spanish Ministry of Science and Innovation. AV is supported by a FPU fellowship from the Spanish Ministry of Education.

This is an open access article., EMT is a complex process whereby cells lose cell-cell interactions and other epithelial properties whilst acquiring a migratory and mesenchymal phenotype. EMT is presently recognized as an important even for tumor invasion and metastasis. Functional E-cadherin loss is a hallmark of EMT and required for tumor invasion in the majority of carcinomas. Transcriptional downregulation is one of the major mechanisms for E-cadherin suppression in carcinomas. In the last decade several E-cadherin repressors, belonging to different transcriptional families, have been identified that, importantly, also act as potent EMT inducers. One of the last additions to EMT regulators are the class I bHLH factors E2-2 (also known as TCF4). However, the hierarchical and functional interrelations between the different EMT inducers are still poorly understood. Here, we comment on the new and so far unrecognized function of E2-2 factors in EMT and discuss on the potential interactions among various EMT inducers. Emerging evidence supporting the participation of TCF4 in human malignancies is also discussed. Thus, increasing understanding of EMT and its regulators is providing meaningful insights into the present knowledge on tumor progression., Work at the A. C.’s lab is supported by grants from the Spanish Ministry of Education and Science (SAF2004-00361; SAF2007-63051; Consolider Ingenio 2010/26102) and the EU (MRTN 2004-005428).

The epithelial-mesenchymal transition (EMT) occurs in pre-metastatic cancer cells and is also associated with the acquisition of stem-cell-like characteristics. A molecular link between EMT and stemness now emerges with the finding that Bmi1, a polycomb protein that promotes self-renewal of certain stem-cell populations, is a direct transcriptional target of the EMT inducer, Twist1.

14 páginas, 4 figuras.-- PMID: 19257890 [PubMed].-- PMCID: PMC2656544.-- Información adicional (Suppl. files S1-S6) disponible en: http://www.biomedcentral.com/1471-2407/9/74/additional/, Additional files: 1. Wound healing assay 231-control cells.-- 2. Wound healing assay 231-E-cadherin cells.-- 3. Wound healing assay 231-P-cadherin cells.-- 4. Complete list of genes modulated by E-cadherin and/or P-cadherin (at least 2 fold with respect to control cells) in 231 cells.-- 5. Potential signaling networks mediated by E-cadherin-regulated genes at the biological process level.-- 6. Potential signaling networks mediated by P-cadherin-regulated genes at the biological process level., [Background]: Alterations in the cadherin-catenin adhesion complexes are involved in tumor initiation, progression and metastasis. However, the functional implication of distinct cadherin types in breast cancer biology is still poorly understood., [Methods]: To compare the functional role of E-cadherin and P-cadherin in invasive breast cancer, we stably transfected these molecules into the MDA-MB-231 cell line, and investigated their effects on motility, invasion and gene expression regulation., [Results]: Expression of either E- and P-cadherin significantly increased cell aggregation and induced a switch from fibroblastic to epithelial morphology. Although expression of these cadherins did not completely reverse the mesenchymal phenotype of MDA-MB-231 cells, both E- and P-cadherin decreased fibroblast-like migration and invasion through extracellular matrix in a similar way. Moreover, microarray gene expression analysis of MDA-MB-231 cells after expression of E- and P-cadherins revealed that these molecules can activate signaling pathways leading to significant changes in gene expression. Although the expression patterns induced by E- and P-cadherin showed more similarities than differences, 40 genes were differentially modified by the expression of either cadherin type., [Conclusion]: E- and P-cadherin have similar functional consequences on the phenotype and invasive behavior of MDA-MB-231 cells. Moreover, we demonstrate for the first time that these cadherins can induce both common and specific gene expression programs on invasive breast cancer cells. Importantly, these identified genes are potential targets for future studies on the functional consequences of altered cadherin expression in human breast cancer., This work has been supported by grants from the Fundación Mutua Madrileña (2006) and SAF2007-63075 to GMB; SAF 2007-63051 to AC; PI051890 and SAF2004-08258-C02-01 to JP. David Sarrió currently is a recipient of a Marie Curie Intra-European Fellowship of the European Commission (PIEF-GA-2008-221083). Gema Moreno-Bueno is a junior investigator of the "Ramón y Cajal Program" of the Spanish Ministry of Education and Science (2004).

17 pages, 8 figures, 4 tables, The expression of the cell-cell adhesion molecules E- and P-cadherin has been analyzed in seven mouse epidermal keratinocyte cell lines representative of different stages of epidermal carcinogenesis. An inverse correlation between the amount of E-cadherin protein and tumorigenicity of the cell lines has been found, together with a complete absence of E-cadherin protein and mRNA expression in three carcinoma cell lines (the epithelioid HaCa4 and the fibroblastoid CarB and CarC cells). A similar result has been detected in tumors induced in nude mice by the cell lines, where induction of E-cadherin expression takes place in moderately differentiated squamous cell carcinomas induced by HaCa4 cells, although at much lower levels than in well-differentiated tumors induced by the epithelial PDV or PDVC57 cell lines. Complete absence of E-cadherin expression has been observed in spindle cell carcinomas induced by CarB or CarC cells. P-cadherin protein was detected in all cell lines that exhibit an epithelial (MCA3D, AT5, PDV, and PDVC57) or epithelioid (HaCa4) morphology, as well as in nude mouse tumors, independent of their tumorigenic capabilities. However, complete absence of P-cadherin was observed in the fibroblast-like cells (CarB and CarC) and in spindle cell carcinomas. The introduction of an exogenous E-cadherin cDNA into HaCa4 cells, or reactivation of the endogenous E-cadherin gene, leads to a partial suppression of the tumorigenicity of this highly malignant cell line. These results suggest a role for E-cadherin in the progression to malignancy of mouse epidermal carcinogenesis. They also suggest that the loss of both E- and P-cadherin could be associated to the final stage of carcinogenesis, the development of spindle cell carcinomas., This work was supported by the DGICYT (research grant PM88-0004).

Lysyl oxidase-like 2 (Loxl2) interacts with and stabilizes Snai1 transcription factor, promoting epithelial-mesenchymal transition. Either Loxl2 or Snai1 knock-down blocks tumor growth and induces differentiation, but the specific role of each factor in tumor progression is still unknown. Comparison of the gene expression profiles of the squamous cell carcinoma cell line HaCa4 after knocking-down Loxl2 or Snai1 revealed that a subset of epidermal differentiation genes was specifically upregulated in Loxl2-silenced cells. In agreement, although both Loxl2- and Snai1-knockdown cells showed reduced in vivo invasion, only Loxl2-silenced cells exhibited a skin-like epidermal differentiation program. In addition, we show that expression of Loxl2 and Snai1 correlates with malignant progression in a two-stage mouse skin carcinogenesis model. Furthermore, we found that increased expression of both LOXL2 and SNAI1 correlates with local recurrence in a cohort of 256 human laryngeal squamous cell carcinomas. We describe for the first time that high levels of LOXL2 are associated with decreased overall and disease-free survival in laryngeal squamous cell carcinomas, lung squamous cell carcinoma, and lymph node-negative (N0) breast adenocarcinomas. Altogether, our results show that LOXL2 can be used as a new poor prognosis indicator in human squamous cell carcinomas promoting malignant transformation by both SNAI1-dependent and SNAI1-independent pathways. ©2008 American Association for Cancer Research., Grant support: Spanish Ministry of Education and Science SAF2004-00361, SAF2007-63051, NAN2004-09230-C04-02, Consolider-Ingenio2010-26102, and the EU MRTN-CT-2004-005428 (A. Cano), the Fundación Mutua Madrileña 2006 and the Spanish Ministry of Education and Science SAF2007-63075 (G. Moreno-Bueno), and the Scientific Foundation of AECC (H. Peinado and M. Mendiola). G. Moreno-Bueno is a junior research investigator ofthe Ramon y Cajal program 2004.

Snai1 (Snail) and Snai2 (Slug), the two main members of Snail family factors, are important mediators of epithelial-mesenchymal transitions and involved in tumor progression. We recently reported that Snai1 plays a major role in tumor growth, invasion and metastasis, but the contribution of Snai2 to tumorigenesis is not yet well understood. To approach this question we have silenced Snai2 and/or Snai1 by stable RNA interference in two independent mouse skin carcinoma (HaCa4 and CarB) cell lines. We demonstrate that Snai2 knockdown has a milder effect, but collaborates with Snai1 silencing in reduction of tumor growth potential of either carcinoma cell line when injected into nude mice. Importantly, Snai1 or Snai2 silencing dramatically influences the metastatic ability of squamous carcinoma HaCa4 cells, inducing a strong reduction in liver and lung distant metastasis. However, only Snai1 knockdown has an effective action on invasiveness and fully abolishes tumor cell dissemination into the spleen. These results demonstrate that Snai1 and Snai2 collaborate on primary tumor growth and specifically contribute to site-specific metastasis of HaCa4 cells. These data also indicate that Snai1 is the major regulator of local invasion, supporting a hierarchical participation of both factors in the metastatic process. © 2008 Macmillan Publishers Limited All rights reserved., This work was supported by grants from the Spanish Ministry of Education and Science (SAF2004-00361; SAF2007-63051; NAN2004-09230-C04-02; Consolider-Ingenio CSD00C-2007-26102) and the EU (MRTN-CT-2004-005428).

International audience; INTRODUCTION: Snail, a family of transcriptional repressors implicated in cell movement, has been correlated with tumour invasion. The Plasminogen Activation (PA) system, including urokinase plasminogen activator (uPA), its receptor and its inhibitor, plasminogen activator inhibitor type 1(PAI-1), also plays a key role in cancer invasion and metastasis, either through proteolytic degradation or by non-proteolytic modulation of cell adhesion and migration. Thus, Snail and the PA system are both over-expressed in cancer and influence this process. In this study we aimed to determine if the activity of SNAI1 (a member of the Snail family) is correlated with expression of the PA system components and how this correlation can influence tumoural cell migration. METHODS: We compared the invasive breast cancer cell-line MDA-MB-231 expressing SNAI1 (MDA-mock) with its derived clone expressing a dominant-negative form of SNAI1 (SNAI1-DN). Expression of PA system mRNAs was analysed by cDNA microarrays and real-time quantitative RT-PCR. Wound healing assays were used to determine cell migration. PAI-1 distribution was assessed by immunostaining. RESULTS: We demonstrated by both cDNA microarrays and real-time quantitative RT-PCR that the functional blockade of SNAI1 induces a significant decrease of PAI-1 and uPA transcripts. After performing an in vitro wound-healing assay, we observed that SNAI1-DN cells migrate more slowly than MDA-mock cells and in a more collective manner. The blockade of SNAI1 activity resulted in the redistribution of PAI-1 in SNAI1-DN cells decorating large lamellipodia, which are commonly found structures in these cells. CONCLUSIONS: In the absence of functional SNAI1, the expression of PAI-1 transcripts is decreased, although the protein is redistributed at the leading edge of migrating cells in a manner comparable with that seen in normal epithelial cells.

During progression of melanoma, loss of the cell-cell adhesion molecule E-cadherin contributes to uncontrolled growth and invasive behavior of transformed melanocytes. Secreted protein acidic and rich in cysteine (SPARC) is a nonstructural matricellular protein that regulates cell-matrix interactions leading to alterations in cell adhesion and proliferation. Overexpression of SPARC has been associated with progression of various cancers, including melanoma; however, its role in primary tumor development is not well defined. We show that normal human melanocytes overexpressing SPARC adopt a fibroblast-like morphology, concomitant with loss of E-cadherin and P-cadherin expression, and increased expression of mesenchymal markers. Concurrent with these changes, SPARC expression stimulates melanocyte motility and melanoma cell invasion. Expression of SPARC results in transcriptional down-regulation of E-cadherin that correlates with induction of Snail, a repressor of E-cadherin. Conversely, SPARC depletion leads to up-regulation of E-cadherin and reduces Snail levels, and SPARC-null cells exhibit a marked change in their mesenchymal phenotype. Finally, analysis of SPARC, Snail, and E-cadherin levels in melanocytes and malignant melanoma cell lines further supports the functional relationship among these proteins during melanoma progression. Our findings provide evidence for the role of SPARC in early transformation of melanocytes and identify a novel mechanism, whereby tumor-derived SPARC promotes tumorigenesis by mediating Snail induction and E-cadherin suppression. (Cancer Res 2006; 66(15): 7516-23)

13 páginas, 9 figuras.-- et al., The transcription factor Snail controls epithelial–mesenchymal transitions (EMT) by repressing E-cadherin expression and other epithelial genes. However, the mechanisms involved in the regulation of Snail function are not fully understood. Here we show that lysyl-oxidase-like 2 and 3 (LOXL2 and LOXL3), two members of the lysyl-oxidase gene family, interact and cooperate with Snail to downregulate E-cadherin expression. Snail's lysine residues 98 and 137 are essential for Snail stability, functional cooperation with LOXL2/3 and induction of EMT. Overexpression of LOXL2 or LOXL3 in epithelial cells induces an EMT process, supporting their implication in tumor progression. The biological importance of LOXL2 is further supported by RNA interference of LOXL2 in Snail-expressing metastatic carcinoma cells, which led to a strong decrease of tumor growth associated to increased apoptosis and reduced expression of mesenchymal and invasive/angiogenic markers. Taken together, these results establish a direct link between LOXL2 and Snail in carcinoma progression., This work was supported by the Spanish Ministry of Education and Science (SAF01-02819 and SAF04-00361 to AC and BMC2002-0383 to MAN) and Instituto de Salud Carlos III, RTICCC (FIS03 C03/10) to AC and FP. HP was supported by a grant from Justesa Imagen, SA.

Whereas accepted models of tumorigenesis exist for genetic lesions, the timing of epigenetic alterations in cancer is not clearly understood. We have analyzed the profile of aberrations in DNA methylation occurring in cells lines and primary tumors of one of the best-characterized mouse carcinogenesis systems, the multistage skin cancer progression model. Initial analysis using high-performance capillary electrophoresis and immunolocalization revealed a loss of genomic 5-methylcytosine associated with the degree of tumor aggressiveness. Paradoxically, this occurs in the context of a growing number of hypermethylated CpG islands of tumor suppressor genes at the most malignant stages of carcinogenesis. We have observed this last phenomenon using two approaches, a candidate gene approach, studying genes with well-known methylation-associated silencing in human tumors, and a mouse cDNA microarray expression analysis after treatment with DNA demethylating drugs. The transition from epithelial to spindle cell morphology is particularly associated with major epigenetic alterations, such as E-cadherin methylation, demethylation of the Snail promoter, and a decrease of the global DNA methylation. Analysis of data obtained from the cDNA microarray strategy led to the identification of new genes that undergo methylation-associated silencing and have growth-inhibitory effects, such as the insulin-like growth factor binding protein-3. Most importantly, all of the above genes were also hypermethylated in human cancer cell lines and primary tumors, underlining the value of the mouse skin carcinogenesis model for the study of aberrant DNA methylation events in cancer cells.

Copyright © by American Society for Cell Biology.-- Final full-text version of the paper available at: http://www.molbiolcell.org/content/vol14/issue7/ .-- Supplementary material available at: http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=165681&blobname=mbc_14_7_2844__.html, β-catenin is a multifunctional protein involved in cell-cell adhesion and Wnt signal transduction. β-Catenin signaling has been proposed to act as inducer of cell proliferation in different tumors. However, in some developmental contexts and cell systems β-catenin also acts as a positive modulator of apoptosis. To get additional insights into the role of β-Catenin in the regulation of the cell cycle and apoptosis, we have analyzed the levels and subcellular localization of endogenous β-catenin and its relation with adenomatous polyposis coli (APC) during the cell cycle in S-phase–synchronized epithelial cells. β-Catenin levels increase in S phase, reaching maximum accumulation at late G2/M and then abruptly decreasing as the cells enter into a new G1 phase. In parallel, an increased cytoplasmic and nuclear localization of β-catenin and APC is observed during S and G2 phases. In addition, strong colocalization of APC with centrosomes, but not β-catenin, is detected in M phase. Interestingly, overexpression of a stable form of β-catenin, or inhibition of endogenous β-catenin degradation, in epidermal keratinocyte cells induces a G2 cell cycle arrest and leads to apoptosis. These results support a role for β-catenin in the control of cell cycle and apoptosis at G2/M in normal and transformed epidermal keratinocytes., This work was supported by grants from the Comisión Interministerial de Ciencia y Tecnología (SAF98–0085-C03–01 and SAF2001–2819), Instituto de Salud Carlos III (FIS01/1174) and Comunidad Autónoma de Madrid (08.1/0055/2000) to AC. During the realization of this work D.O. was a predoctoral fellow of the Spanish Ministry of Science and Technology.

14 pages, 8 figures., The mechanisms underlying downregulation of the cadherin/catenin complexes and β-catenin signaling during tumor progression are not fully understood. We have analyzed the effect of oncogenic H-Ras on E-cadherin/catenin complex formation/stabilization and β-catenin distribution in epidermal keratinocytes. Microinjection or stable expression of V12Ras into keratinocytes promotes the loss of E-cadherin and α-catenin and relocalization of β-catenin to the cytoplasm and nucleus. Moreover, these effects are dependent on PI3K (phosphoinositide 3-OH kinase) activity. Interestingly, a strong association of p85α and p110α subunits of PI3K with β-catenin is induced in V12Ras-expressing keratinocytes, and in vitro binding assays show a direct interaction between β-catenin and p85α. Overexpression of either V12Ras or constitutively active p110α induces metabolic stabilization of β-catenin and promotes its accumulation in cytoplasmic and nuclear pools. In addition, the interaction of β-catenin with the adenomatous polyposis coli protein is blocked in V12Ras and p110α transformants though no changes in glycogen synthase kinase 3 β activity could be detected. Nevertheless, in V12Ras transformants the in vivo phosphorylation of β-catenin in Ser residues is strongly decreased. These results indicate that H-Ras activation induces the relocalization and cytoplasmic stabilization of β-catenin by a mechanism involving its interaction with PI3K., This work was supported by grants to A. Cano from the Spanish Commision Interministerial de Ciencia y Tecnología (SAF95-0818 and SAF98-0085-C03-01) and Comunidad Autónoma de Madrid (08.1/020/1997). V.M.M. Braga is supported by the Cancer Research Campaign.

The Ela gene region of adenovirus 5 produces five mRNAs. The major 289R and 243R proteins are encoded by the two most abundant mRNAs, denoted as 13S and 12S, respectively (for a review see 1). The Ela gene from adenovirus type 5 is implicated in many cellular effects such as blocking of differentiation apoptosis and induction of chemosensitivity and radiosensitivity (for a review see 21). Moreover, Ela has been shown to be able to induce apoptosis by p53-independent mechanism after DNA damage or other situations (2, 3). Adenovirus 5 Ela protein may inhibit interferon-stimulated gene expression, and induce susceptibility of mammalian cells to lysis by natural killer lymphocytes (26). Most, if not all, of the biological effects of Ela are related to the binding of different cellular proteins, such as p33, p60 (Cyclin A), p105 (pRb), p107, p130, p300, p400, CBP, Dr1, YY1 (for review see 1).

The influence of plakoglobin on the phenotype and tumorigenicity of murine spindle carcinoma cells was analyzed by stable transfection of plakoglobin cDNA in the presence or absence of E-cadherin expression. In either situation, overexpression of plakoglobin was unable to modify the fibroblastic phenotype or to completely suppress the tumorigenic behavior of the spindle cells, but a moderate reduction in the growth rate of the tumors was induced by plakoglobin and was further enhanced by E-cadherin. Coexpression of E-cadherin and plakoglobin induced a mutual stabilization, increasing the half-life of both molecules in the double transfectants more than 5- and 30-fold, respectively, with a turnover rate similar to that observed in control keratinocytes. The stabilization of E-cadherin, as well as that of plakoglobin, was maintained in the tumors induced by the double transfectants, in contrast to the unstable expression of E-cadherin observed in tumors induced in plakoglobin-deficient cells. The E-cadherin/catenin complexes present in the double transfectants were functional in calcium- dependent aggregation assays and similar in composition to those of control keratinocytes. However, most of the components of the complexes of the transfectants were solubilized by non-ionic detergents, indicating a weak interaction with the actin cytoskeleton. These results indicated that restoration of E-cadherin/catenin complexes was not sufficient to induce the transition of the fibroblastic cells to an epithelial phenotype or to completely suppress the tumorigenicity of mouse skin spindle carcinoma cells., This work was supported by grants from the Spanish Comisión Interministerial de Ciencia y Tecnología (SAF92-0146 and SAF95-0818) to AC. During the conduct of this study, EL was a recipient of a predoctoral fellowship from the Spanish Ministry of Education and Science.

During centrifugation of Dictyostelium membranes on sucrose and metrizamide gradients, an ATPase activity resistant to azide and molybdate but sensitive to diethylstilbestrol was found to copurify with the plasma membrane markers alkaline phosphatase and 125I in cells surface-labelled by lactoperoxidase catalyzed iodination. This ATPase was enriched 50-fold in purified plasma membranes and could be separated from the mitochondrial ATPase on metrizamide gradients. The plasma membrane ATPase is very specific for ATP as substrate and Mg2+ as essential cofactor. Its pH optimum is 6.5 and it is inhibited by dicyclohexylcarbodiimide, diethylstilbestrol, vanadate, mercurials and Cu2+, but not by ouabain, molybdate, azide or oligomycin. It was not specifically affected by either monovalent cations or anions. These results suggest that the plasma membranes of Dictyostelium contain an ATPase similar to the proton-pumping ATPases recently identified in fungal and plant plasma membranes (Serrano, R. (1984) Curr. Top. Cell. Regul. 23, 87-126). © 1985., This work was supported by grants from the Spanish Comisión Asesora de Investigación Científica y Técnica and Fondo de Investigaciones Sanitarias.