The coordinated activity of estrogens and epidermal growth factor receptor (EGFR) family agonists represents the main determinant of breast cancer cell proliferation. Stromal cellderived factor-1 (SDF-1) enhances extracellular signal-regulated kinases 1 and 2 (ERK1/2) activity via the transactivation of EGFR and 17␤-estradiol (E2) induces SDF-1 production to exert autocrine proliferative effects. On this basis, we evaluated whether the inhibition of the tyrosine kinase (TK) activity of EGFR may control different mitogenic stimuli in breast tumors using the EGFR-TK inhibitor gefitinib to antagonize the proliferation induced by E2 in T47D human breast cancer cells. EGF, E2, and SDF-1 induced a dose-dependent T47D cell proliferation, that being nonadditive suggested the activation of common intracellular pathways. Gefitinib treatment inhibited not only the EGF-dependent proliferation and ERK1/2 activation but also the effects of SDF-1 and E2, suggesting that these activities were mediated by EGFR transactivation. Indeed, both SDF-1 and E2 caused EGFR tyrosine phosphorylation. The molecular link between E2 and SDF-1 proliferative effects was identified because 1,1Ј-(1,4-phenylenebis(methylene))-bis-1,4,8,11-tetraazacyclotetradecane octahydrochloride (AMD3100), a CXCR4 antagonist, inhibited SDF-1-and E2-dependent proliferation and EGFR and ERK1/2 phosphorylation. EGFR transactivation was dependent on c-Src activation. E2 treatment caused a powerful SDF-1 release from T47D cells. Finally, in SKBR3, E2-resistant cells, EGFR was constitutively activated, and AMD3100 reduced EGFR phosphorylation and cell proliferation, whereas HER2-neu was transactivated by SDF-1 in SKBR3 but not in T47D cells. In conclusion, we show that activation of CXCR4 transduces proliferative signals from the E2 receptor to EGFR, whose inhibition is able to revert breast cancer cell proliferation induced by multiple receptor activation.Breast cancer is the most frequent cause of cancer-related deaths in women. Whether or not breast cancers are estrogen-dependent represents a critical factor for patients' prognosis and feasibility of antiestrogenic therapy. Two thirds of breast carcinomas express estrogen receptor-␣ (ER␣) and most of them are responsive to antiestrogens or aromatase inhibitors (Nilsson et al., 2001). However, many initially responsive, ER␣-positive breast carcinomas frequently acquire resistance to endocrine therapy. The overexpression or This work was supported by a research grant from Astra-Zeneca (Milano, Italy) and Italian Association for Cancer Research.Article, publication date, and citation information can be found at

Somatostatin inhibits cell proliferation through the activation of five receptors (SSTR1-5) expressed in normal and cancer cells. We analyzed the role of individual SSTRs in the antiproliferative activity of somatostatin in C6 rat glioma cells. Somatostatin dose-dependently inhibited C6 proliferation, an effect mimicked, with different efficacy or potency, by BIM-23745, BIM-23120, BIM-23206 (agonists for SSTR1, -2, and -5) and octreotide. The activation of SSTR3 was ineffective, although all SSTRs are functionally active, as demonstrated by the inhibition of cAMP production. All SSTRs induced cytostatic effects through the activation of the phosphotyrosine phosphatase PTPeta and the inhibition of ERK1/2. For possible synergism between SSTR subtypes, we tested the effects of the combined treatment with two agonists (SSTR1+2 or SSTR2+5) or bifunctional compounds. The simultaneous activation of SSTR1 and SSTR2 slightly increased the efficacy of the individual compounds with an IC50 in between the single receptor activation. SSTR2+5 activation displayed a pattern of response superimposable to that of the SSTR5 agonist alone (low potency and higher efficacy, as compared with BIM-23120). The simultaneous activation of SSTR1, -2, and -5 resulted in a response similar to somatostatin. In conclusion, the cytostatic effects of somatostatin in C6 cells are mediated by the SSTR1, -2, and -5 through the same intracellular pathway: activation of PTPeta and inhibition of ERK1/2 activity. Somatostatin is more effective than the individual agonists. The combined activation of SSTR1 and -2 shows a partial synergism as far as antiproliferative activity, whereas SSTR2 and -5 activation results in a response resembling the SSTR5 effects.

BackgroundCancer stem cells (CSCs) are considered the cell subpopulation responsible for breast cancer (BC) initiation, growth, and relapse. CSCs are identified as self-renewing and tumor-initiating cells, conferring resistance to chemo- and radio-therapy to several neoplasias. Nowadays, th (about 10mM)e pharmacological targeting of CSCs is considered an ineludible therapeutic goal. The antidiabetic drug metformin was reported to suppress in vitro and in vivo CSC survival in different tumors and, in particular, in BC preclinical models. However, few studies are available on primary CSC cultures derived from human postsurgical BC samples, likely because of the limited amount of tissue available after surgery. In this context, comparative oncology is acquiring a relevant role in cancer research, allowing the analysis of larger samples from spontaneous pet tumors that represent optimal models for human cancer.MethodsIsolation of primary canine mammary carcinoma (CMC) cells and enrichment in stem-like cell was carried out from fresh tumor specimens by culturing cells in stem-permissive conditions. Phenotypic and functional characterization of CMC-derived stem cells was performed in vitro, by assessment of self-renewal, long-lasting proliferation, marker expression, and drug sensitivity, and in vivo, by tumorigenicity experiments. Corresponding cultures of differentiated CMC cells were used as internal reference. Metformin efficacy on CMC stem cell viability was analyzed both in vitro and in vivo.ResultsWe identified a subpopulation of CMC cells showing human breast CSC features, including expression of specific markers (i.e. CD44, CXCR4), growth as mammospheres, and tumor-initiation in mice. These cells show resistance to doxorubicin but were highly sensitive to metformin in vitro. Finally, in vivo metformin administration significantly impaired CMC growth in NOD-SCID mice, associated with a significant depletion of CSCs.ConclusionsSimilarly to the human counterpart, CMCs contain stem-like subpopulations representing, in a comparative oncology context, a valuable translational model for human BC, and, in particular, to predict the efficacy of antitumor drugs. Moreover, metformin represents a potential CSC-selective drug for BC, as effective (neo-)adjuvant therapy to eradicate CSC in mammary carcinomas of humans and animals.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1235-8) contains supplementary material, which is available to authorized users.

Aims-A sound predictive test is lacking for the identification of cirrhotic patients at high risk of developing hepatocellular carcinoma. The present study evaluates the measurement of hepatocyte expression of silver stained nucleolar organiser region (AgNOR) proteins as a risk factor for the development of hepatocellular carcinoma in cirrhosis. Conclusions-These results demonstrate that a high hepatocyte proliferation rate is a major risk factor for hepatocellular carcinoma development in the cirrhotic liver. Therefore, the evaluation of the hepatocyte proliferation rate is very important to identify patients requiring a more strict follow up programme for early diagnosis of hepatocellular carcinoma. Methods-Liver

Interferons (IFNs) play a crucial role in the host's immune response and other homeostatic control actions. Three IFN types and several IFN families within the types allow for a plethora of regulatory actions. The number of distinct IFN molecules is highest among type I IFNs and, in particular, within the IFN-a family. In pigs, there are 17 IFN-a subtypes with different antiviral activities and different expression profiles; however, no data are available about biological properties other than the antiviral effector activities. Therefore, 16 porcine IFN-a genes were cloned, expressed in mammalian Chinese hamster ovary cells, and characterized for antiviral, anti-inflammatory, and MHC-modulating activities at a pre-established level of 10 IU/mL. Antiviral activity: IFN-a2, -a5, -a9, and -a10 showed the highest level of activity in a pseudorabies virus yield reduction assay. On the contrary, little, if any, activity was shown by IFN-a3, -a7, -a13, -a4, and -a15. Anti-inflammatory activity: With the exception of IFNs-a2, -a7, -a9, and -a11, all IFN-a subtypes had significant anti-inflammatory control activity in an interleukin-8 (IL-8) yield reduction assay. Gene expression analyses showed that some IFN-a subtypes can significantly downregulate the expression of IL-8, tumor necrosis factor a (TNF-a), IL-6, Toll-like receptor 4 (TLR4), bD1, and nuclear factor-kB (NF-kB) genes, while maintaining or upregulating the expression of bD4. Immunomodulation: A significant upregulation of class I and/or class II MHC was induced by all the IFNs under study, with the exception of IFNs-a11, -a15, and -a16, which instead significantly downregulated class I MHC. Our results indicate that gene duplications in the porcine IFN-a family underlie diverse effector and regulatory activities, being therefore instrumental in host survival and environmental adaptation. This role of IFN-a could be founded on fine-tuning and regulation of pro-and anti-inflammatory control actions after exposure to both infectious and noninfectious environmental stressors.