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Cancer cells within a tumor are functionally heterogeneous and specific subpopulations, defined as cancer initiating cells (CICs), are endowed with higher tumor forming potential. The CIC state, however, is not hierarchically stable and conversion of non-CICs to CICs under microenvironment signals might represent a determinant of tumor aggressiveness. How plasticity is regulated at the cellular level is however poorly understood. To identify determinants of plasticity in lung cancer we exposed eight different cell lines to TGFβ1 to induce EMT and stimulate modulation of CD133+ CICs. We show that response to TGFβ1 treatment is heterogeneous with some cells readily switching to stem cell state (1.5–2 fold CICs increase) and others being unresponsive to stimulation. This response is unrelated to original CICs content or extent of EMT engagement but is tightly dependent on balance between epithelial and mesenchymal features as measured by the ratio of expression of CDH1 (E-cadherin) to SNAI2. Epigenetic modulation of this balance can restore sensitivity of unresponsive models to microenvironmental stimuli, including those elicited by cancer-associated fibroblasts both in vitro and in vivo. In particular, tumors with increased prevalence of cells with features of partial EMT (hybrid epithelial/mesenchymal phenotype) are endowed with the highest plasticity and specific patterns of expression of SNAI2 and CDH1 markers identify a subset of tumors with worse prognosis. In conclusion, here we describe a connection between a hybrid epithelial/mesenchymal phenotype and conversion to stem-cell state in response to external stimuli. These findings have implications for current endeavors to identify tumors with increased plasticity. •Signals from the microenvironment are involved in modulation of cancer initiating cells (CICs) in lung cancer.•Balance between epithelial/mesenchymal features is a crucial determinant of proclivity to stemness phenotype acquisition.•Epigenetic modification of epithelial/mesenchymal balance can regulate response to microenvironmental stimuli.•A specific pattern of expression of E-cadherin and SNAI2 is associated with worst prognosis in NSCLC.

Background CDCP1, a transmembrane protein with tumor pro-metastatic activity, was recently identified as a prognostic marker in TNBC, the most aggressive breast cancer subtype still lacking an effective molecular targeted therapy. The mechanisms driving CDCP1 over-expression are not fully understood, although several stimuli derived from tumor microenvironment, such as factors present in Wound Healing Fluids (WHFs), reportedly increase CDCP1 levels. Methods The expression of CDCP1, PDGFRβ and ERK1/2cell was tested by Western blot after stimulation of MDA-MB-231 cells with PDGF-BB and, similarly, in presence or not of ERK1/2 inhibitor in a panel of TNBC cell lines. Knock-down of PDGFRβ was established in MDA-MB-231 cells to detect CDCP1 upon WHF treatment. Immunohistochemical staining was used to detect the expression of CDCP1 and PDGFRβ in TNBC clinical samples. Results We discovered that PDGF-BB-mediated activation of PDGFRβ increases CDCP1 protein expression through the downstream activation of ERK1/2. Inhibition of ERK1/2 activity reduced per se CDCP1 expression, evidence strengthening its role in CDCP1 expression regulation. Knock-down of PDGFRβ in TNBC cells impaired CDCP1 increase induced by WHF treatment, highlighting the role if this receptor as a central player of the WHF-mediated CDCP1 induction. A significant association between CDCP1 and PDGFRβ immunohistochemical staining was observed in TNBC specimens, independently of CDCP1 gene gain, thus corroborating the relevance of the PDGF-BB/PDGFRβ axis in the modulation of CDCP1 expression. Conclusion We have identified PDGF-BB/PDGFRβ–mediated pathway as a novel player in the regulation of CDCP1 in TNCBs through ERK1/2 activation. Our results provide the basis for the potential use of PDGFRβ and ERK1/2 inhibitors in targeting the aggressive features of CDCP1-positive TNBCs.

An increasing body of evidence highlights an intriguing interaction between microRNAs and transcriptional factors involved in determining cell fate, including the well known “genome guardian” p53. Here we show that miR-205, oncosuppressive microRNA lost in breast cancer, is directly transactivated by oncosuppressor p53. Moreover, evaluating miR-205 expression in a panel of cell lines belonging to the highly aggressive triple negative breast cancer (TNBC) subtype, which still lacks an effective targeted therapy and characterized by an extremely undifferentiated and mesenchymal phenotype, we demonstrated that this microRNA is critically down-expressed compared to a normal-like cell line. Re-expression of miR-205 where absent strongly reduces cell proliferation, cell cycle progression and clonogenic potential in vitro, and inhibits tumor growth in vivo, and this tumor suppressor activity is at least partially exerted through targeting of E2F1, master regulator of cell cycle progression, and LAMC1, component of extracellular matrix involved in cell adhesion, proliferation and migration. ► miR-205 is downregulated in triple negative breast cancer. ► miR-205 directly targets LAMC1 and E2F1. ► miR-205 inhibits cellular proliferation in vitro and in vivo. ► miR-205 induces cellular senescence. ► p53 regulates miR-205 expression.

Background TPC-1 is a papillary thyroid carcinoma (PTC)-derived cell line that spontaneously expresses the oncogene RET/PTC1 . TPC-1 treated with the RET/PTC1 inhibitor RPI-1 displayed a cytostatic and reversible inhibition of cell proliferation and a strong activation of focal adhesion kinase (FAK). As dasatinib inhibition of Src results in reduction of FAK activation, we evaluated the effects of TPC-1 treatment with dasatinib in combination with RPI-1. Results Dasatinib (100 nM) strongly reduced TPC-1 proliferation and induced marked changes in TPC-1 morphology. Cells appeared smaller and more contracted, with decreased cell spreading, due to the inhibition of phosphorylation of important cytoskeletal proteins (p130 CAS , Crk, and paxillin) by dasatinib. The combination of RPI-1 with dasatinib demonstrated enhanced effects on cell proliferation (more than 80% reduction) and on the phosphotyrosine protein profile. In particular, RPI-1 reduced the phosphorylation of RET, MET, DCDB2, CTND1, and PLCγ, while dasatinib acted on the phosphorylation of EGFR, EPHA2, and DOK1. Moreover, dasatinib completely abrogated the phosphorylation of FAK at all tyrosine sites (Y576, Y577, Y861, Y925) with the exception of the autoactivation site (Y397). Notably, the pharmacological treatments induced an overexpression of integrin β1 (ITB1) that was correlated with a mild enhancement in phosphorylation of ERK1/2 and STAT3, known for their roles in prevention of apoptosis and in increase of proliferation and survival. A reduction in Akt, p38 and JNK1/2 activation was observed. Conclusions All data demonstrate that the combination of the two drugs effectively reduced cell proliferation (by more than 80%), significantly decreased Tyr phosphorylation of almost all phosphorylable proteins, and altered the morphology of the cells, supporting high cytostatic effects. Following the combined treatment, cell survival pathways appeared to be mediated by STAT3 and ERK activities resulting from integrin clustering and FAK autophosphorylation. EphA2 may also contribute, at least in part, to integrin and FAK activation. In conclusion, these data implicate ITB1 and EphA2 as promising therapeutic targets in PTC.

We recently showed that differential expression of extracellular matrix (ECM) genes delineates four subgroups of breast carcinomas (ECM1, -2, -3- and -4) with different clinical outcome. To further investigate the characteristics of ECM signature and its impact on tumor progression, we conducted unsupervised clustering analyses in 6 additional independent datasets of invasive breast tumors from different platforms for a total of 643 samples. Use of four different clustering algorithms identified ECM3 tumors as an independent group in all datasets tested. ECM3 showed a homogeneous gene pattern, consisting of 58 genes encoding 43 structural ECM proteins. From 26 to 41% of the cases were ECM3-enriched, and analysis of datasets relevant to gene expression in neoplastic or corresponding stromal cells showed that both stromal and breast carcinoma cells can coordinately express ECM3 genes. In in vitro experiments, β-estradiol induced ECM3 gene production in ER-positive breast carcinoma cell lines, whereas TGFβ induced upregulation of the genes leading to ECM3 gene classification, especially in ER-negative breast carcinoma cells and in fibroblasts. Multivariate analysis of distant metastasis-free survival in untreated breast tumor patients revealed a significant interaction between ECM3 and histological grade (p = 0.001). Cox models, estimated separately in grade I-II and grade III tumors, indicated a highly significant association between ECM3 and worse survival probability only in grade III tumors (HR = 3.0, 95% CI = 1.3-7.0, p = 0.0098). Gene Set Enrichment analysis of ECM3 compared to non-ECM3 tumors revealed significant enrichment of epithelial-mesenchymal transition (EMT) genes in both grade I-II and grade III subsets of ECM3 tumors. Thus, ECM3 is a robust cluster that identifies breast carcinomas with EMT features but with accelerated metastatic potential only in the undifferentiated (grade III) phenotype. These findings support the key relevance of neoplastic and stroma interaction in breast cancer progression.

Background Current insights into the effects of iron deficiency in tumour cells are not commensurate with the importance of iron in cell metabolism. Studies have predominantly focused on the effects of oxygen or glucose scarcity in tumour cells, while attributing insufficient emphasis to the inadequate supply of iron in hypoxic regions. Cellular responses to iron deficiency and hypoxia are interlinked and may strongly affect tumour metabolism. Methods We examined the morphological, proteomic, and metabolic effects induced by two iron chelators—deferoxamine (DFO) and di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT)—on MDA-MB-231 and MDA-MB-157 breast cancer cells. Results These chelators induced a cytoplasmic massive vacuolation and accumulation of lipid droplets (LDs), eventually followed by implosive, non-autophagic, and non-apoptotic death similar to methuosis. Vacuoles and LDs are generated by expansion of the endoplasmic reticulum (ER) based on extracellular fluid import, which includes unsaturated fatty acids that accumulate in LDs. Typical physiological phenomena associated with hypoxia are observed, such as inhibition of translation, mitochondrial dysfunction, and metabolic remodelling. These survival-oriented changes are associated with a greater expression of epithelial/mesenchymal transcription markers. Conclusions Iron starvation induces a hypoxia-like program able to scavenge nutrients from the extracellular environment, and cells assume a hypertrophic phenotype. Such survival strategy is accompanied by the ER-dependent massive cytoplasmic vacuolization, mitochondrial dysfunctions, and LD accumulation and then evolves into cell death. LDs containing a greater proportion of unsaturated lipids are released as a consequence of cell death. The consequence of the disruption of iron metabolism in tumour tissue and the effects of LDs on intercellular communication, cancer–inflammation axis, and immunity remain to be explored. Considering the potential benefits, these are crucial subjects for future mechanistic and clinical studies.

Fibulin-1 (Fbln-1) is an immunogenic breast cancer-related glycoprotein identified by serological analysis of cDNA expression library (SEREX) strategy. Here, we show that dendritic cells from two breast cancer patients elicited a CD4 + -mediated T-cell response to Fbln-1 presentation. In both patients, an antibody response to Fbln-1 was also found. By contrast, a Fbln-1-seronegative patient and a weakly seropositive patient demonstrated no such T-cell response. Analysis of human breast cancers for Fbln-1 RNA and protein expression revealed the presence of Fbln-1C and -1D variants. Fbln-1 was detected in the cytoplasm and at the cell surface of different human breast carcinoma cell lines. Immunohistochemical analysis of 528 archival primary breast carcinomas showed the expression of Fbln-1 in 35% of the cases. When the immunohistochemical findings were compared against pathobiological information associated with each specimen, an inverse relationship between Fbln-1 and cathepsin D expression was observed ( P =0.04). Furthermore, even though long-term survival was similar between Fbln-1-positive and -negative cases, the survival of Fbln-1-positive cases improved when a lymphoid infiltrate was present at the tumour site. Taken together, our findings of an Fbln-1-specific immunity and the improved survival associated with Fbln-1 expression in the presence of lymphoid infiltration point to a role of Fbln-1 in tumour immunosurveillance.

Immune and epithelial cells express TLR3, a receptor deputed to respond to microbial signals activating the immune response. The prognostic value of TLR3 in cancer is debated and no data are currently available in NSCLC, for which therapeutic approaches that target the immune system are providing encouraging results. Dissecting the lung immune microenvironment could provide new prognostic markers, especially for early stage NSCLC for which surgery is the only treatment option. In this study we investigated the expression and the prognostic value of TLR3 on both tumor and immune compartments of stage I NSCLCs. In a cohort of 194 NSCLC stage I, TLR3 immunohistochemistry expression on tumor cells predicted a favorable outcome of early stage NSCLC, whereas on the immune cells infiltrating the tumor stroma, TLR3 expression associated with a poor overall survival. Patients with TLR3-positive immune infiltrating cells, but not tumor cells showed a worse prognosis compared with all other patients. The majority of TLR3-expressing immune cells resulted to be macrophages and TLR3 expression associates with PD-1 expression. TLR3 has an opposite prognostic significance when expressed on tumor or immune cells in early stage NCSCL. Analysis of TLR3 in tumor and immune cells can help in identifying high risk stage I patients for which adjuvant treatment would be beneficial.

CDCP1, a transmembrane protein with tumor pro-metastatic activity, was recently identified as a prognostic marker in TNBC, the most aggressive breast cancer subtype still lacking an effective molecular targeted therapy. The mechanisms driving CDCP1 over-expression are not fully understood, although several stimuli derived from tumor microenvironment, such as factors present in Wound Healing Fluids (WHFs), reportedly increase CDCP1 levels. The expression of CDCP1, PDGFR[beta] and ERK1/2cell was tested by Western blot after stimulation of MDA-MB-231 cells with PDGF-BB and, similarly, in presence or not of ERK1/2 inhibitor in a panel of TNBC cell lines. Knock-down of PDGFR[beta] was established in MDA-MB-231 cells to detect CDCP1 upon WHF treatment. Immunohistochemical staining was used to detect the expression of CDCP1 and PDGFR[beta] in TNBC clinical samples. We discovered that PDGF-BB-mediated activation of PDGFR[beta] increases CDCP1 protein expression through the downstream activation of ERK1/2. Inhibition of ERK1/2 activity reduced per se CDCP1 expression, evidence strengthening its role in CDCP1 expression regulation. Knock-down of PDGFR[beta] in TNBC cells impaired CDCP1 increase induced by WHF treatment, highlighting the role if this receptor as a central player of the WHF-mediated CDCP1 induction. A significant association between CDCP1 and PDGFR[beta] immunohistochemical staining was observed in TNBC specimens, independently of CDCP1 gene gain, thus corroborating the relevance of the PDGF-BB/PDGFR[beta] axis in the modulation of CDCP1 expression. We have identified PDGF-BB/PDGFR[beta]-mediated pathway as a novel player in the regulation of CDCP1 in TNCBs through ERK1/2 activation. Our results provide the basis for the potential use of PDGFR[beta] and ERK1/2 inhibitors in targeting the aggressive features of CDCP1-positive TNBCs.

Triple negative breast cancer (TNBC) is a very aggressive subgroup of breast carcinoma, still lacking specific markers for an effective targeted therapy and with a poorer prognosis compared to other breast cancer subtypes. In this study we investigated the possibility that TNBC cells contribute to the establishment of tumor vascular network by the process known as vasculogenic mimicry, through endothelial cell differentiation. Vascular-like functional properties of breast cancer cell lines were investigated in vitro by tube formation assay and in vivo by confocal microscopy, immunofluorescence or immunohistochemistry on frozen tumor sections. TNBCs express endothelial markers and acquire the ability to form vascular-like channels in vitro and in vivo, both in xenograft models and in human specimens, generating blood lacunae surrounded by tumor cells. Notably this feature is significantly associated with reduced disease free survival. The impairment of the main pathways involved in vessel formation, by treatment with inhibitors (i.e. Sunitinib and Bevacizumab) or by siRNA-mediating silencing, allowed the identification of PDGFRβ and FGFR2 as relevant players in this phenomenon. Inhibition of these tyrosine kinase receptors negatively affects vascular lacunae formation and significantly inhibits TNBC growth in vivo. In summary, we demonstrated that TNBCs have the ability to form vascular-like channels in vitro and to generate blood lacunae lined by tumor cells in vivo. Moreover, this feature is associated with poor outcome, probably contributing to the aggressiveness of this breast cancer subgroup. Finally, PDGFRβ and FGFR2-mediated pathways, identified as relevant in mediating this characteristic, potentially represent valid targets for a specific therapy of this breast cancer subgroup. •TNBCs show capability to perform in vitro and in vivo Vasculogenic Mimicry (VM).•In TNBC the n of vascular lacunae is significantly higher and associated with DFS.•Tumor cells performing in vivo VM express endothelial and mesenchymal markers.•Sunitinib strongly inhibits VM and induces tumor regression in TNBC models.•SiRNA-mediated silencing revealed a crucial role for PDGFRβ and FGFR2 in VM.