Tetrahydrouridine Inhibits Cell Proliferation through Cell Cycle Regulation Regardless of Cytidine Deaminase Expression Levels

Tetrahydrouridine (THU) is a well characterized and potent inhibitor of cytidine deaminase (CDA). Highly expressed CDA catalyzes and inactivates cytidine analogues, ultimately contributing to increased gemcitabine resistance. Therefore, a combination therapy of THU and gemcitabine is considered to be a potential and promising treatment for tumors with highly expressed CDA. In this study, we found that THU has an alternative mechanism for inhibiting cell growth which is independent of CDA expression. Three different carcinoma cell lines (MIAPaCa-2, H441, and H1299) exhibited decreased cell proliferation after sole administration of THU, while being unaffected by knocking down CDA. To investigate the mechanism of THU-induced cell growth inhibition, cell cycle analysis using flow cytometry was performed. This analysis revealed that THU caused an increased rate of G1-phase occurrence while S-phase occurrence was diminished. Similarly, Ki-67 staining further supported that THU reduces cell proliferation. We also found that THU regulates cell cycle progression at the G1/S checkpoint by suppressing E2F1. As a result, a combination regimen of THU and gemcitabine might be a more effective therapy than previously believed for pancreatic carcinoma since THU works as a CDA inhibitor, as well as an inhibitor of cell growth in some types of pancreatic carcinoma cells

Growth and Production of Shiitake Mushrooms on Lignocellulosic Waste Materials

Shiitake mushrooms have not previously been cultivated on a large scale in South Dakota. This research project was, therefore, conducted to generate baseline information about the growth and mushroom production potential of L. edodes on agricultural and forestry residues available in the state. It was anticipated that this information could then be used as a basis upon which further research projects could be designed, with the ultimate goal of establishing a shiitake mushroom production industry in South Dakota. In order to accomplish this goal of defining the baseline metabolic requirements and characteristics of L. edodes, the project addressed five main questions: 1. What are the general morphological characteristics and growth rates of different strains of L. edodes on various agar media? 2. What media and environmental conditions are best suited for maintaining shiitake culture collections at this facility? 3. What liquid media provides the best submerged culture growth of L. edodes? 4. Can shiitake mushrooms be produced on substrate materials found in South Dakota? 5. Can shiitake production be used as an aid in biodegradation of waste materials? Answers to these questions were based on, and developed from, the data gathered in the three phases of this experiment