We recently reported that activation of Trop-2 through its cleavage at R87-T88 by ADAM10 underlies Trop-2–driven progression of colon cancer. However, the mechanism of action and pathological impact of Trop-2 in metastatic diffusion remain unexplored. Through searches for molecular determinants of cancer metastasis, we identified TROP2 as unique in its up-regulation across independent colon cancer metastasis models. Overexpression of wild-type Trop-2 in KM12SM human colon cancer cells increased liver metastasis rates in vivo in immunosuppressed mice. Metastatic growth was further enhanced by a tail-less, activated ΔcytoTrop-2 mutant, indicating the Trop-2 tail as a pivotal inhibitory signaling element. In primary tumors and metastases, transcriptome analysis showed no down-regulation of CDH1 by transcription factors for epithelial-to-mesenchymal transition, thus suggesting that the pro-metastatic activity of Trop-2 is through alternative mechanisms. Trop-2 can tightly interact with ADAM10. Here, Trop-2 bound E-cadherin and stimulated ADAM10-mediated proteolytic cleavage of E-cadherin intracellular domain. This induced detachment of E-cadherin from β-actin, and loss of cell-cell adhesion, acquisition of invasive capability, and membrane-driven activation of β-catenin signaling, which were further enhanced by the ΔcytoTrop-2 mutant. This Trop-2/E-cadherin/β-catenin program led to anti-apoptotic signaling, increased cell migration, and enhanced cancer-cell survival. In patients with colon cancer, activation of this Trop-2–centered program led to significantly reduced relapse-free and overall survival, indicating a major impact on progression to metastatic disease. Recently, the anti-Trop-2 mAb Sacituzumab govitecan-hziy was shown to be active against metastatic breast cancer. Our findings define the key relevance of Trop-2 as a target in metastatic colon cancer.

Trop-2 is a transmembrane signal transducer that can induce cancer growth. Using antibody targeting and N-terminal Edman degradation, we show here that Trop-2 undergoes cleavage in the first thyroglobulin domain loop of its extracellular region, between residues R87 and T88. Molecular modeling indicated that this cleavage induces a profound rearrangement of the Trop-2 structure, which suggested a deep impact on its biological function. No Trop-2 cleavage was detected in normal human tissues, whereas most tumors showed Trop-2 cleavage, including skin, ovary, colon, and breast cancers. Coimmunoprecipitation and mass spectrometry analysis revealed that ADAM10 physically interacts with Trop-2. Immunofluorescence/confocal time-lapse microscopy revealed that the two molecules broadly colocalize at the cell membrane. We show that ADAM10 inhibitors, siRNAs and shRNAs abolish the processing of Trop-2, which indicates that ADAM10 is an effector protease. Proteolysis of Trop-2 at R87-T88 triggered cancer cell growth both in vitro and in vivo. A corresponding role was shown for metastatic spreading of colon cancer, as the R87A-T88A Trop-2 mutant abolished xenotransplant metastatic dissemination. Activatory proteolysis of Trop-2 was recapitulated in primary human breast cancers. Together with the prognostic impact of Trop-2 and ADAM10 on cancers of the skin, ovary, colon, lung, and pancreas, these data indicate a driving role of this activatory cleavage of Trop-2 on malignant progression of tumors.

Streptococcus mitis, a normal inhabitant of the oral cavity, is a member of Viridans Group Streptococci (VGS). Generally recognized as a causative agent of invasive diseases in immunocompromised patients, S. mitis is considered to have low pathogenic potential in immunocompetent individuals. We present a rare case of sinusitis complicated by meningitis and cerebral sino-venous thrombosis (CSVT) caused by S. mitis in a previously healthy 12-year-old boy with poor oral health status. With the aim of understanding the real pathogenic role of this microorganism, an extensive review of the literature about invasive diseases due to S. mitis in pediatric patients was performed. Our data define the critical role of this microorganism in invasive infections, especially in immunocompetent children and in the presence of apparently harmful conditions such as sinusitis and caries. Attention should be paid to the choice of therapy because of VGS’s emerging antimicrobial resistance patterns.

Methods: CuO NPs (80AE20 nm as determined by dynamic light scattering) were synthesized by the precipitation method. Intracellular accumulation of CuO NPs was measured by atomic absorption spectroscopy. The panel of cell lines included HCT116 colon and MDA-MB-231 triple-negative breast carcinomas as well as K562 (CML) cell line and its multidrug-resistant K562/4 subline. The cytotoxicity of CuO NPs, NAC and their combination were determined in MTT assays. Flow cytometry was used to analyze the mechanisms of cell response. Caspase-3 and poly(ADPribose) polymerase (PARP) were detected by immunoblotting.Results: CuO NPs showed a slight toxicity for all tested cell lines after 72 h, while in combination with the non-toxic NAC a rapid (within 2 h) ROS generation and cell death by 8 h were detected. CuO NPs weakly accumulated in the cells, so ROS generation is likely to occur mainly outside the cells. The IC 50 of the combination was 2-3 orders of magnitude smaller compared to NPs alone. Death associated events differed between the cell lines but generally caspase-independent apoptosis was followed by irreversible damage of the plasma membrane. Importantly, the combination of CuO NPs with NAC was equally potent for K562 cells and the multidrugresistant K562/4 subline. Reduction of Cu 2+ to Cu + upon interaction with the thiol group in NAC can trigger ROS formation. Conclusions:The combination of CuO NPs and NAC killed human tumor cell lines including the multidrug-resistant variant. Rapid ROS generation can be promising in situations where tumor cells acquire multidrug resistance during treatment. Also, engineering of supramolecular systems will allow to guide copper to critical cysteine residues in specific proteins for their oxidative destruction.

Granulicatella spp. are non-motile, non-sporulating, facultatively anaerobic Gram-positive cocci. Throughout the literature, these organisms have been referred to by several names, such as “nutritionally deficient streptococci”, “vitamin-B dependent streptococci” and “pyridoxal-dependent streptococci”, because of their fastidious nutritional requirements, which can often make culture isolation challenging. Known to be a member of the normal microbiota of the human oral cavity and urogenital and intestinal tracts, similar to other streptococci, Granulicatella spp. can cause bacteremia, sepsis and infective endocarditis. Considering the difficulty in growing this organism on culture medium, the fact that it is now included among the bacteria known to be responsible for culture-negative infective endocarditis suggests that its pathogenic role could be highly underestimated. Moreover, being considered such a rare causative agent, it is not a target of standard antibiotic empiric treatment. We present a rare case of G. elegans endocarditis in a young child and review the medical literature on Granulicatella endocarditis in the pediatric population, with the aim of sharing knowledge about this microorganism, which can be challenging for a clinician who is not familiar with it.