Helicobacter pylori infection, the main risk factor for gastric cancer (GC), leads to an epithelial–mesenchymal transition (EMT) of gastric epithelium contributing to gastric cancer stem cell (CSC) emergence. The Hippo pathway effectors yes-associated protein (YAP) and transcriptional co-activator with PDZ binding motif (TAZ) control cancer initiation and progression in many cancers including GC. Here, we investigated the role of TAZ in the early steps of H. pylori-mediated gastric carcinogenesis. TAZ implication in EMT, invasion, and CSC-related tumorigenic properties were evaluated in three gastric epithelial cell lines infected by H. pylori. We showed that H. pylori infection increased TAZ nuclear expression and transcriptional enhancer TEA domain (TEAD) transcription factors transcriptional activity. Nuclear TAZ and zinc finger E-box-binding homeobox 1 (ZEB1) were co-overexpressed in cells harboring a mesenchymal phenotype in vitro, and in areas of regenerative hyperplasia in gastric mucosa of H. pylori-infected patients and experimentally infected mice, as well as at the invasive front of gastric carcinoma. TAZ silencing reduced ZEB1 expression and EMT phenotype, and strongly inhibited invasion and tumorsphere formation induced by H. pylori. In conclusion, TAZ activation in response to H. pylori infection contributes to H. pylori-induced EMT, invasion, and CSC-like tumorigenic properties. TAZ overexpression in H. pylori-induced pre-neoplastic lesions and in GC could therefore constitute a biomarker of early transformation in gastric carcinogenesis.

Cancer stem cells (CSCs) present chemo-resistance mechanisms contributing to tumour maintenance and recurrence, making their targeting of utmost importance in gastric cancer (GC) therapy. The Hippo pathway has been implicated in gastric CSC properties and was shown to be regulated by leukaemia inhibitory factor receptor (LIFR) and its ligand LIF in breast cancer. This study aimed to determine LIF’s effect on CSC properties in GC cell lines and patient-derived xenograft (PDX) cells, which remains unexplored. LIF’s treatment effect on CSC markers expression and tumoursphere formation was evaluated. The Hippo kinase inhibitor XMU-MP-1 and/or the JAK1 inhibitor Ruxolitinib were used to determine Hippo and canonical JAK/STAT pathway involvement in gastric CSCs’ response to LIF. Results indicate that LIF decreased tumorigenic and chemo-resistant CSCs, in both GC cell lines and PDX cells. In addition, LIF increased activation of LATS1/2 Hippo kinases, thereby decreasing downstream YAP/TAZ nuclear accumulation and TEAD transcriptional activity. LIF’s anti-CSC effect was reversed by XMU-MP-1 but not by Ruxolitinib treatment, highlighting the opposite effects of these two pathways downstream LIFR. In conclusion, LIF displays anti-CSC properties in GC, through Hippo kinases activation, and could in fine constitute a new CSCs-targeting strategy to help decrease relapse cases and bad prognosis in GC.

During the first trimester of 2020, the Ministry of Health of Costa Rica reported the first three cases of primary amebic meningoencephalitis (PAM). In two cases, laboratory personnel of the hospitals preliminarily identified amoeboid forms in cerebrospinal fluid (CSF) samples. For the molecular confirmation of species, CSF samples were sent to our laboratory. We carried out microscopic analyses and exflagellation assays. Besides, samples were cultured in 2% casein hydrolysate medium and in non-nutrient agar plates supplemented with Escherichia coli. Finally, PCR and sequencing were employed for the molecular diagnosis and species identification. In all cases, the presence of Naegleria fowleri was confirmed. An environmental investigation to identify the possible infection sources was also performed. Water samples from hot springs and groundwater from an artisan well were collected and after filtration and culture in non-nutrient agar plates supplemented with E. coli, thermotolerance and exflagellation assays were carried out. For the positive samples, PCR and sequencing were performed, confirming the presence of N. fowleri in several water samples. The report of these cases and the possible association with hot springs has had a significant impact on the population and health authorities of Costa Rica.

SARS-CoV-2 receptor binding domain (RBD) recognizes the angiotensin converting enzyme 2 (ACE2) receptor in host cells that enables infection. Due to its antigenic specificity, RBD production is important for development of serological assays. Here we have established a system for stable RBD production in HEK 293T mammalian cells that simultaneously express the recombinant fluorescent protein dTomato, which enables kinetic monitoring of RBD expression by fluorescence microscopy. In addition, we have validated the use of this recombinant RBD in an ELISA assay for the detection of anti-RBD antibodies in serum samples of COVID-19 convalescent patients. Recombinant RBD generated using this approach can be useful for generation of antibody-based therapeutics against SARS-CoV-2, as well serological assays aimed to test antibody responses to this relevant virus.