A Comprehensive Analysis of Human Endogenous Retroviruses HERV-K (HML.2) from Teratocarcinoma Cell Lines and Detection of Viral Cargo in Microvesicles

About 8% of our genome is composed of sequences from Human Endogenous Retroviruses (HERVs). The HERV-K (HML.2) family, here abbreviated HML.2, is able to produce virus particles that were detected in cell lines, malignant tumors and in autoimmune diseases. Parameters and properties of HML.2 released from teratocarcinoma cell lines GH and Tera-1 were investigated in detail. In most experiments, analyzed viruses were purified by density gradient centrifugation. HML.2 structural proteins, reverse transcriptase (RT) activity, viral RNA (vRNA) and particle morphology were analyzed. The HML.2 markers were predominantly detected in fractions with a buoyant density of 1.16 g/cm3. Deglycosylation of TM revealed truncated forms of transmembrane (TM) protein. Free virions and extracellular vesicles (presumably microvesicles—MVs) with HML.2 elements, including budding intermediates, were detected by electron microscopy. Viral elements and assembled virions captured and exported by MVs can boost specific immune responses and trigger immunomodulation in recipient cells. Sequencing of cDNA clones demonstrated exclusive presence of HERV-K108 env in HML.2 from Tera-1 cells. Not counting two recombinant variants, four known env sequences were found in HML.2 from GH cells. Obtained results shed light on parameters and morphology of HML.2. A possible mechanism of HML.2-induced diseases is discussed.

Bis-Bibenzyls from the Liverwort Pellia endiviifolia and Their Biological Activity

Based on previous investigations where bis-bibenzyls isolated from liverworts showed various biological activities (cytotoxic, antimicrobial, and antiviral), we investigated their cytotoxic activity in several human cancer cell lines. From the methylene-chloride/methanol extract of the liverwort Pellia endiviifolia, three bis-bibenzyls of the perrottetin type were isolated, namely perrottetin E, 10′-hydroxyperrottetin E, and 10,10′-dihydroxyperrottetin E. The last two were found for the first time in this species. Their structures were resolved using 1D and 2D NMR, as well as by comparison with data in the literature. Cytotoxic activity of the isolated compounds was tested on three human leukemia cell lines, HL-60 (acute promyelocytic leukemia cells), U-937 (acute monocytic leukemia cells), and K-562 (human chronic myelogenous leukemia cells), as well as on human embryonal teratocarcinoma cell line (NT2/D1) and human glioblastoma cell lines A-172 and U-251, and compared to the previously isolated bis-bibenzyls (perrottetins) of similar structure. The isolated compounds exhibited modest activity against leukemia cells and significant activity against NT2/D1 and A-172. Overall, the most active cytotoxic compounds in this investigation were perrottetin E (1), isolated in this work from Pellia endiviifolia, and perrottetin F phenanthrene derivative (7), previously isolated from Lunularia cruciata and added for a comparison of their cytotoxic activity.

Stem Cell Treatment for Ischemic Stroke Recovery

The role of cellular transplantation to promote functional recovery after stroke has been evaluated over the last two decades. Preclinical studies first established the potential for cultured neuronal cells derived from a teratocarcinoma cell line to be tested for safety and efficacy in the treatment of human stroke. In animal models of stroke that caused reproducible learning and motor deficits, injection of neuronal cells resulted in a return of learning behavior, retention time, and motor function. Clinical trials followed. Additional work with cells derived from a bone marrow neuroprogenitor line, fetal cortical stem cells, and other cell sources showed promise in preclinical studies and then these cells were tested in clinical studies. This report reviews the different biological repair approaches using cell implants, discusses clinical trial design and surgical methods, and the current state of research.

Lysine methylation represses p53 activity in teratocarcinoma cancer cells

TP53 (which encodes the p53 protein) is the most frequently mutated gene among all human cancers, whereas tumors that retain the wild-type TP53 gene often use alternative mechanisms to repress the p53 tumor-suppressive function. Testicular teratocarcinoma cells rarely contain mutations in TP53, yet the transcriptional activity of wild-type p53 is compromised, despite its high expression level. Here we report that in the teratocarcinoma cell line NTera2, p53 is subject to lysine methylation at its carboxyl terminus, which has been shown to repress p53’s transcriptional activity. We show that reduction of the cognate methyltransferases reactivates p53 and promotes differentiation of the NTera2 cells. Furthermore, reconstitution of methylation-deficient p53 mutants into p53-depleted NTera2 cells results in elevated expression of p53 downstream targets and precocious loss of pluripotent gene expression compared with re-expression of wild-type p53. Our results provide evidence that lysine methylation of endogenous wild-type p53 represses its activity in cancer cells and suggest new therapeutic possibilities of targeting testicular teratocarcinoma.

The overexpression of SOX2 affects the migration of human teratocarcinoma cell line NT2/D1

The altered expression of the SOX2 transcription factor is associated with oncogenic or tumor suppressor functions in human cancers. This factor regulates the migration and invasion of different cancer cells. In this study we investigated the effect of constitutive SOX2 overexpression on the migration and adhesion capacity of embryonal teratocarcinoma NT2/D1 cells derived from a metastasis of a human testicular germ cell tumor. We detected that increased SOX2 expression changed the speed, mode and path of cell migration, but not the adhesion ability of NT2/D1 cells. Additionally, we demonstrated that SOX2 overexpression increased the expression of the tumor suppressor protein p53 and the HDM2 oncogene. Our results contribute to the better understanding of the effect of SOX2 on the behavior of tumor cells originating from a human testicular germ cell tumor. Considering that NT2/D1 cells resemble cancer stem cells in many features, our results could contribute to the elucidation of the role of SOX2 in cancer stem cells behavior and the process of metastasis.

Quercetin reduces pluripotency, migration and adhesion of human teratocarcinoma cell line NT2/D1 by inhibiting Wnt/β-catenin signaling

In human teratocarcinoma cell line NT2/D1 quercetin exerts its anticancer effect through the inhibition of Wnt signaling.