The tumor suppressor semaphorin 3B triggers a prometastatic program mediated by interleukin 8 and the tumor microenvironment

Semaphorins are a large family of evolutionarily conserved morphogenetic molecules originally identified for their repelling role in axonal guidance. Intriguingly, semaphorins have recently been implicated in cancer progression (Neufeld, G., T. Lange, A. Varshavsky, and O. Kessler. 2007. Adv. Exp. Med. Biol. 600:118–131). In particular, semaphorin 3B (SEMA3B) is considered a putative tumor suppressor, and yet we found that it is expressed at high levels in many invasive and metastatic human cancers. By investigating experimental tumor models, we confirmed that SEMA3B expression inhibited tumor growth, whereas metastatic dissemination was surprisingly increased. We found that SEMA3B induced the production of interleukin (IL) 8 by tumor cells by activating the p38–mitogen-activated protein kinase pathway in a neuropilin 1–dependent manner. Silencing the expression of endogenous SEMA3B in tumor cells impaired IL-8 transcription. The release of IL-8, in turn, induced the recruitment of tumor-associated macrophages and metastatic dissemination to the lung, which could be rescued by blocking IL-8 with neutralizing antibodies. In conclusion, we report that SEMA3B exerts unexpected functions in cancer progression by fostering a prometastatic environment through elevated IL-8 secretion and recruitment of macrophages coupled to the suppression of tumor growth

Advanced age, time to treatment and long-term mortality: single centre data from the FAST-STEMI network

Background. Optimization of the techniques and larger accessibility to mechanical reperfusion have significantly improved the outcomes of patients with ST-segment elevation myocardial infarction (STEMI). However, suboptimal results have been observed in certain higher-risk subsets of patients, as in advanced age, where the benefits of primary PCI are more debated. We evaluated the impact of systematic primary percutaneous coronary intervention (PCI) and an optimized STEMI network on the long-term prognosis from a single centre experience.Methods. We included STEMI patients included in the FAST-STEMI network between 2016 and 2019. Ischemia duration was defined as the time from symptoms onset to coronary reopening (pain-to-balloon, PTB). The primary study endpoint (PE) was a composite of mortality and recurrent MI at long-term follow-up. Indywidual outcome endpoints were also assessed.Results. We included 253 patients undergoing primary PCI and discharged alive. Mean age was 67.2 ± 12.5 years, 75.1% males and 19.8% diabetics. At a median follow-up of 581 [307–922] days, the primary endpoint occurred in 24 patients (7.9%), of whom 5.5% died. The occurrence of a cardiovascular event was significantly associated with advanced age (p < 0.001), renal failure (p = 0.03), lower ejection fraction at discharge (p = 0.04) and longer in-hospital stay (p = 0.01). The median PTB was 198 minutes [IQR: 125–340 min], that was significantly longer among patients experiencing the PE (p = 0.01). A linear relationship was observed between age and PTB (r = 0.13, p = 0.009). However, both age ≥ 75 years and PTB above the median emerged as independent predictors of the primary endpoint (age: HR [95%CI] = 5.56 [2.26–13.7], p < 0.001, PTB: HR [95%CI] = 3.59 [1.39–9.3], p = 0.01). Similar results were observed for overall mortality.Conclusion. The present study shows that among STEMI patients undergoing primary PCI in a single centre, the duration of ischemia and advance age are independently associated to long-term mortality and recurrent myocardial infarction. However, longer time to reperfusion was observed among elderly patients

Expression of Met protein and urokinase-type plasminogen activator receptor (uPA-R) in papillary carcinoma of the thyroid.

Met protein encoded by MET oncogene is the high affinity receptor for hepatocyte growth factor (HGF)/scatter factor (SF). HGF/SF has to be cleaved in its heterodimeric form by the urokinase-type plasminogen activator (uPA) to become active as a ligand for Met receptor. The expression of Met protein and of the high affinity receptor for uPA. (uPA-R) was investigated in 39 samples of papillary carcinoma using immunohistochemistry. Reactivity for Met protein was present in 33 of 34 tumours, mostly with a diffuse pattern of staining. Reactivity for uPA-R was present in 78 per cent of papillary tumours and exhibited a pattern of staining similar to that of Met protein. Staining for uPA-R was present in 23 of 25 cases (92 per cent) of papillary carcinoma with prominent sclerosis, and in only 1 of 7 eases (14 per cent) without sclerosis. Peritumoural normal thyroid, follicular adenomas, and follicular carcinomas were negative for Mel protein and for uPA-R. Hyperfunctioning tall thyroid cells showed weak membrane reactivity for uPA-R and for Met protein. The findings of immunohistochemistry were confirmed at the mRNA level using in situ hybridization, since the signal for uPA-R and Met RNAs was detected in most tumour cells of five cases of papillary carcinoma

Src-mediated activation of α-diacylglycerol kinase is required for hepatocyte growth factor-induced cell motility

Diacylglycerol kinases are involved in cell signaling, either as regulators of diacylglycerol levels or as intracellular signal-generating enzymes. However, neither their role in signal transduction nor their biochemical regulation has been elucidated. Hepatocyte growth factor (HGF), upon binding to its tyrosine kinase receptor, activates multiple signaling pathways stimulating cell motility, scattering, proliferation and branching morphogenesis. Herein we demonstrate that: (i) the enzymatic activity of α-diacylglycerol kinase (αDgk) is stimulated by HGF in epithelial, endothelial and αDgk-transfected COS cells; (ii) cellular expression of an αDgk kinase-defective mutant inhibits activation of endogenous αDgk acting as dominant negative; (iii) specific inhibition of αDgk prevents HGF-induced cell movement of endothelial cells; (iv) HGF induces the association of αDgk in a complex with Src, whose tyrosine kinase activity is required for αDgk activation by HGF; (v) Src wild type stimulates αDgk activity in vitro; and (vi) αDgk can be tyrosine phosphorylated in intact cells

Mutant Met-mediated transformation is ligand-dependent and can be inhibited by HGF antagonists

Mutations in the genes encoding for Met, Ret and Kit receptor tyrosine kinases invariably result in increased kinase activity and in the acquisition of transforming potential. However, the requirement of receptor ligands for the transformation process is still unclear. We have investigated the role of hepatocyte growth factor (HGF), the high-affinity ligand for Met, in mutant Met-mediated cell transformation. We provide evidence that the transforming potential displayed by mutant forms of Met found in human cancer is not only sensitive but entirely dependent on the presence of HGF, by showing that mutant Met transforms NIH3T3 fibroblasts, which produce endogenous HGF, but is not able to transform epithelial cells, unless exogenous HGF is supplied. Accordingly, mutant Met-induced transformation of NIH3T3 cells can be inhibited by HGF antagonists and increased by HGF stimulation. We also show that an engineered Met receptor which contains an oncogenic mutation but is impaired in its ability to bind HGF completely loses its transforming activity, which can be rescued by causing receptor dimerization using a monoclonal antibody. These results indicate that point mutations resulting in Met kinase activation are necessary but not sufficient to cause cell transformation, the latter being dependent on ligand-induced receptor dimerization. They also suggest that mutant Met-driven tumour growth depends on the availability and tissue distribution of active HGF, and provide proof-of-concept for the treatment of mutant-Met related pathologies by HGF-antagonizing drugs

MicroRNA 483‐3p overexpression unleashes invasive growth of metastatic colorectal cancer via NDRG1 downregulation and ensuing activation of the ERBB3/AKT axis

In colorectal cancer, the mechanisms underlying tumor aggressiveness require further elucidation. Taking advantage of a large panel of human metastatic colorectal cancer xenografts and matched stem‐like cell cultures (m‐colospheres), here we show that the overexpression of microRNA 483‐3p (miRNA‐483‐3p; also known as MIR‐483‐3p), encoded by a frequently amplified gene locus, confers an aggressive phenotype. In m‐colospheres, endogenous or ectopic miRNA‐483‐3p overexpression increased proliferative response, invasiveness, stem cell frequency, and resistance to differentiation. Transcriptomic analyses and functional validation found that miRNA‐483‐3p directly targets NDRG1, known as a metastasis suppressor involved in EGFR family downregulation. Mechanistically, miRNA‐483‐3p overexpression induced the signaling pathway triggered by ERBB3, including AKT and GSK3β, and led to the activation of transcription factors regulating epithelial–mesenchymal transition (EMT). Consistently, treatment with selective anti‐ERBB3 antibodies counteracted the invasive growth of miRNA‐483‐3p‐overexpressing m‐colospheres. In human colorectal tumors, miRNA‐483‐3p expression inversely correlated with NDRG1 and directly correlated with EMT transcription factor expression and poor prognosis. These results unveil a previously unrecognized link between miRNA‐483‐3p, NDRG1, and ERBB3‐AKT signaling that can directly support colorectal cancer invasion and is amenable to therapeutic targeting

(A) MDA-MB435 (MDA) and A549 cells transduced to express SEMA3B (3B) or a noncoding EV were grown in culture for 4 d in 1% FBS

Cell growth was evaluated daily in separate dishes by staining cells with crystal violet and measuring absorbance. Data shown represent the mean and SD of triplicates.(B and C) SEMA3B-transduced and EV control tumor cells were injected subcutaneously into nude mice. Graphs display tumor volume (measured externally during the experiment; B) and tumor weight (measured after excision at the end of the experiment; C), respectively. Data shown are the mean ± SEM from nine mice per each experimental group. ***, P < 0.0005. (D) The expression of SEMA3B (Myc tagged) was detected in tumors by staining tissue sections with anti-Myc antibodies (green), whereas nuclear counterstaining was done with DAPI (blue). Bar, 100 μm. SEMA3B was similarly detected in tumor lysates by Western blotting (bottom). (E) At the end of the experiment, the lungs of mice carrying tumor xenografts (as described above) were contrasted by airway perfusion with India ink, and superficial metastases were counted under a stereoscopic microscope. Numbers of metastases are given as the mean ± SD from nine mice for each experimental group (left). We further determined the metastatic index of SEMA3B-expressing and control tumors (right) by calculating the ratio between the number of metastatic foci and tumor weight. **, P < 0.01; ***, P < 0.001. (F) A549 cells expressing SEMA3B under control of a doxycycline-inducible promoter were injected subcutaneously in nude mice. Tumor cells expressing the transactivator rTTA alone were used as controls. After 46 d, the mice were killed, and we measured tumor burden, counted lung metastasis, and calculated the metastatic index as described. Data shown are the mean ± SEM. Western blot analysis on protein lysates from tumor samples (top) revealed a minimum level of recombinant SEMA3B expression in the absence of the doxycycline, which was strongly induced by treatment with the drug. *, P < 0.05; **, P < 0.01.<p><b>Copyright information:</b></p><p>Taken from "The tumor suppressor semaphorin 3B triggers a prometastatic program mediated by interleukin 8 and the tumor microenvironment"</p><p></p><p>The Journal of Experimental Medicine 2008;205(5):1155-1171.</p><p>Published online 12 May 2008</p><p>PMCID:PMC2373847.</p><p></p