Novel Pancreatic Cancer Cell Lines Derived from Genetically Engineered Mouse Models of Spontaneous Pancreatic Adenocarcinoma: Applications in Diagnosis and Therapy

Pancreatic cancer (PC) remains one of the most lethal human malignancies with poor prognosis. Despite all advances in preclinical research, there have not been significant translation of novel therapies into the clinics. The development of genetically engineered mouse (GEM) models that produce spontaneous pancreatic adenocarcinoma (PDAC) have increased our understanding of the pathogenesis of the disease. Although these PDAC mouse models are ideal for studying potential therapies and specific genetic mutations, there is a need for developing syngeneic cell lines from these models. In this study, we describe the successful establishment and characterization of three cell lines derived from two (PDAC) mouse models. The cell line UN-KC-6141 was derived from a pancreatic tumor of a Kras^G12D;Pdx1-Cre (KC) mouse at 50 weeks of age, whereas UN-KPC-960 and UN-KPC-961 cell lines were derived from pancreatic tumors of Kras^G12D;Trp53^R172H;Pdx1-Cre (KPC) mice at 17 weeks of age. The cancer mutations of these parent mice carried over to the daughter cell lines (i.e. Kras^G12D mutation was observed in all three cell lines while Trp53 mutation was observed only in KPC cell lines). The cell lines showed typical cobblestone epithelial morphology in culture, and unlike the previously established mouse PDAC cell line Panc02, expressed the ductal marker CK19. Furthermore, these cell lines expressed the epithelial-mesenchymal markers E-cadherin and N-cadherin, and also, Muc1 and Muc4 mucins. In addition, these cell lines were resistant to the chemotherapeutic drug Gemcitabine. Their implantation in vivo produced subcutaneous as well as tumors in the pancreas (orthotopic). The genetic mutations in these cell lines mimic the genetic compendium of human PDAC, which make them valuable models with a high potential of translational relevance for examining diagnostic markers and therapeutic drugs.     

Diverse cellulolytic bacteria isolated from the high humus, alkaline-saline chinampa soils

Aiming at learning the functional bacterial community in the high humus content, saline-alkaline soils of chinampas, the cellulolytic bacteria were quantified and 100 bacterial isolates were isolated and characterized in the present study. Analysis of 16S-23S IGS (intergenic spacer) RFLP (restriction fragment length polymorphism) grouped the isolates into 48 IGS types and phylogenetic analysis of 16S rRNA genes identified them into 42 phylospecies within 29 genera and higher taxa belonging to the phyla Actinobacteria, Firmicutes and Proteobacteria, dominated by the genera Arthrobacter, Streptomyces, Bacillus, Pseudomonas, Pseudoxanthomonas and Stenotrophomonas. Among these bacteria, 63 isolates represent 26 novel putative species or higher taxa, while 37 were members of 17 defined species according to the phylogenetic relationships of 16S rRNA gene. Except for the novel species, the cellulolytic activity was not reported previously in 9 of the 17 species. They degraded cellulose in medium at pH?4.5–10.0 or supplied with NaCl up to 9 %. In addition, 84.8 and 71.7 % of them degraded xylan and Avicel, respectively. These results greatly improved the knowledge about the diversity of cellulolytic bacteria and demonstrated that the chinampa soils contain diverse and novel cellulolytic bacteria functioning at a wide range of pH and salinity levels, which might be a valuable biotechnological resource for biotransformation of cellulose.     

Sistotremastrum guttuliferum: a new species from the Macaronesian islands

Using morphological and molecular data, the new species Sistotremastrum guttuliferum is described from specimens collected in the Azores archipelago, Madeira and Canary Islands. Morphologically, this new species differs from S. niveocremeum and S. suecicum by the small oil drops in the cytoplasm of subicular hyphae and the spore size. An updated key of Sistotremastrum species is provided.     

C2ORF40 suppresses breast cancer cell proliferation and invasion through modulating expression of M phase cell cycle genes

Recently, it has been suggested that C2ORF40 is a candidate tumor suppressor gene in breast cancer. However, the mechanism for reduced expression of C2ORF40 and its functional role in breast cancers remain unclear. Here we show that C2ORF40 is frequently silenced in human primary breast cancers and cell lines through promoter hypermethylation. C2ORF40 mRNA level is significantly associated with patient disease-free survival and distant cancer metastasis. Overexpression of C2ORF40 inhibits breast cancer cell proliferation, migration and invasion. By contrast, silencing C2ORF40 expression promotes these biological phenotypes. Bioinformatics and FACS analysis reveal C2ORF40 functions at G2/M phase by downregulation of mitotic genes expression, including UBE2C. Our results suggest that C2ORF40 acts as a tumor suppressor gene in breast cancer pathogenesis and progression and is a candidate prognostic marker for this disease.     

New insights into the functional roles of reactive oxygen species during embryo sac development and fertilization in Arabidopsis thaliana

Previously considered as toxic by-products of aerobic metabolism, reactive oxygen species (ROS) are emerging as essential signaling molecules in eukaryotes. Recent evidence showed that maintenance of ROS homeostasis during female gametophyte development is crucial for embryo sac patterning and fertilization. Although ROS are exclusively detected in the central cell of mature embryo sacs, the study of mutants deficient in ROS homeostasis suggests that controlled oxidative bursts might take place earlier during gametophyte development. Also, a ROS burst that depends on pollination takes place inside the embryo sac. This oxidative response might be required for pollen tube growth arrest and for sperm cell release. In this mini-review, we will focus on new insights into the role of ROS during female gametophyte development and fertilization. Special focus will be made on the mitochondrial Mn-Superoxide dismutase (MSD1), which has been recently reported to be essential for maintaining ROS homeostasis during embryo sac formation.     

Nitric oxide and cell death in liver cancer cells

Nitric oxide (NO) is a lipophillic, highly diffusible, and short-lived physiological messenger which regulates a variety of physiopathological responses. NO may exert its cellular action through cGMP-dependent and cGMP-independent pathways which includes different postranslational modifications. The effect of NO in cancer depends on the activity and localization of NOS isoforms, concentration and duration of NO exposure, cellular sensitivity, and hypoxia/re-oxygenation process. NO regulates critical factors such as the hypoxia inducible factor-1 (HIF-1) and p53 generally leading to growth arrest, apoptosis or adaptation. NO sensitizes hepatoma cells to chemotherapeutic compounds probably through increased p53 and cell death receptor expressions.     

Urea’s Effect on the Ribonuclease A Catalytic Efficiency: A Kinetic, 1H NMR and Molecular Orbital Study

Understanding of protein–urea interactions is one of the greatest challenges to modern structural protein chemistry. Based in enzyme kinetics experiments and ¹H NMR spectroscopic analysis we proposed that urea, at low concentrations, directly interacts with the protonated histidines of the active center of RNase A, following a simple model of competitive inhibition. These results were supported by theoretical analysis based on the frontier molecular orbital theory and suggest that urea might establish a favorable interaction with the cationic amino acids. Our experimental evidence and theoretical analysis indicate that the initials steps of the molecular mechanism of Urea–RNase A interaction passes through the establishment of a three center four electron adduct. Also, our results would explain the observed disruption of the ¹H NMR signals corresponding to H12 and H119 (involved in catalysis) of the RNase A studied in the presence of urea. Our interaction model of urea–amino acids (cationic) can be extended to explain the inactivation of other enzymes with cationic amino acids at the active site.