Pellino 1 promotes lymphomagenesis by deregulating BCL6 polyubiquitination.

The signal-responsive E3 ubiquitin ligase pellino 1 (PELI1) regulates TLR and T cell receptor (TCR) signaling and contributes to the maintenance of autoimmunity; however, little is known about the consequence of mutations that result in upregulation of PELI1. Here, we developed transgenic mice that constitutively express human PELI1 and determined that these mice have a shorter lifespan due to tumor formation. Constitutive expression of PELI1 resulted in ligand-independent hyperactivation of B cells and facilitated the development of a wide range of lymphoid tumors, with prominent B cell infiltration observed across multiple organs. PELI1 directly interacted with the oncoprotein B cell chronic lymphocytic leukemia (BCL6) and induced lysine 63-mediated BCL6 polyubiquitination. In samples from patients with diffuse large B cell lymphomas (DLBCLs), PELI1 expression levels positively correlated with BCL6 expression, and PELI1 overexpression was closely associated with poor prognosis in DLBCLs. Together, these results suggest that increased PELI1 expression and subsequent induction of BCL6 promotes lymphomagenesis and that this pathway may be a potential target for therapeutic strategies to treat B cell lymphomas.

Importance of PKCδ signaling in fractionated-radiation-induced expansion of glioma-initiating cells and resistance to cancer treatment.

Brain tumors frequently recur or progress as focal masses after treatment with ionizing radiation. However, the mechanisms underlying the repopulation of tumor cells after radiation have remained unclear. In this study, we show that cellular signaling from Abelson murine leukemia viral oncogene homolog (Abl) to protein kinase Cδ (PKCδ) is crucial for fractionated-radiation-induced expansion of glioma-initiating cell populations and acquisition of resistance to anticancer treatments. Treatment of human glioma cells with fractionated radiation increased Abl and PKCδ activity, expanded the CD133-positive (CD133(+)) cell population that possesses tumor-initiating potential and induced expression of glioma stem cell markers and self-renewal-related proteins. Moreover, cells treated with fractionated radiation were resistant to anticancer treatments. Small interfering RNA (siRNA)-mediated knockdown of PKCδ expression blocked fractionated-radiation-induced CD133(+) cell expansion and suppressed expression of glioma stem cell markers and self-renewal-related proteins. It also suppressed resistance of glioma cells to anticancer treatments. Similarly, knockdown of Abl led to a decrease in CD133(+) cell populations and restored chemotherapeutic sensitivity. It also attenuated fractionated-radiation-induced PKCδ activation, suggesting that Abl acts upstream of PKCδ. Collectively, these data indicate that fractionated radiation induces an increase in the glioma-initiating cell population, decreases cellular sensitivity to cancer treatment and implicates activation of Abl-PKCδ signaling in both events. These findings provide insights that might prove pivotal in the context of ionising-radiation-based therapeutic interventions for brain tumors.

Triterpenoid pristimerin synergizes with taxol to induce cervical cancer cell death through reactive oxygen species-mediated mitochondrial dysfunction.

A combined treatment with conventional chemotherapies can enhance the effectiveness of chemotherapeutic agents against cancers. Here, we have shown that the naturally occurring triterpenoids synergistically enhance the response of cervical cancer cells to taxol. Of the triterpenoid compounds, pristimerin enhanced the anticancer effect of taxol with the highest efficiency by combination. Pristimerin synergizes with taxol to inhibit clonogenic survival and tumor growth in nude mice, and to enhance cell death in cervical cancer cells. A combined treatment with taxol and pristimerin induced cervical cancer cell death by increasing intracellular reactive oxygen species levels, upregulation of death receptor death receptor 5 (DR5), activation of Bax, and dissipation of mitochondrial membrane potential. Treatment with N-acetyl-L-cysteine, a thiol-containing antioxidant completely blocked combined treatment-induced Bax translocation as well as DR5 upregulation. Moreover, inhibition of Jun N-terminal kinase/c-Jun pathway attenuated cell death by blocking DR5 upregulation and Bax activation. These results indicate that the triterpenoid, pristimerin, synergistically enhances taxol response of cervical cancer cells through DR5 expression and Bax activation. Furthermore, the reactive oxygen species-dependent activation of the Jun N-terminal kinase/c-Jun pathway is required for the DR5 upregulation and Bax activation. The molecular mechanism revealed by this study may aid in the design of future combination cancer therapies against cells with intrinsically reduced sensitivity to taxol.

[Prognostic significance of TEL/AML1 rearrangement and its additional genetic changes in Korean childhood precursor B-acute lymphoblastic leukemia].

BACKGROUND: TEL (ETV6)/AML1 (RUNX1) rearrangement is observed in approximately 20-25% of childhood precursor B-ALL and is associated with a favorable outcome. Additional genetic changes, associated with TEL/AML1, are frequently found. We evaluated the prevalence and prognostic significance of TEL/AML1 rearrangement and additional genetic changes in the TEL and AML1 genes in Korean childhood precursor B-ALL. METHODS: We performed FISH using LSITEL/AML1 ES probe (Vysis, USA) in 123 children diagnosed as having precursor B-ALL and assessed clinical relevance of the TEL/AML1 rearrangement and additional genetic abnormalities. RESULTS: The frequency of TEL/AML1 was 17.1% (21/123) in patients with precursor B-ALL. TEL/ AML1-positive group showed male predominance (P=0.012) and younger age of onset than TEL/ AML1-negative group by 1.6 yr (P=0.013). The outcome of TEL/AML1-positive group tended to show lower incidences of relapse (1/21 vs 20/102), death (1/21 vs 17/102) and longer event free survival. Among TEL/AML1-positive patients, unrearranged TEL deletion, AML1 gain, and unrearranged TEL deletion combined with AML1 gain were detected in 61.9%, 23.8%, and 9.5%, respectively. There were no significant differences in the clinical features and outcome according to the presence or absence of additional genetic changes. CONCLUSIONS: The frequency of TEL/AML1 and additional genetic changes in TEL and AML1 is higher than previous studies in Korean children, and in close agreement with usually reported one, 20-25%. TEL/AML1-positive group showed a tendency toward better prognosis. Further study is needed to clarify the prognostic significance of additional changes in TEL and AML1 based on a large sample size.

[A case of erythromycin-resistant Ureaplasma urealyticum meningitis in a premature infant].

Ureaplasma urealyticum causes infection or colonization of female genital tracts associated with preterm delivery and infertility and the infection of the bloodstream, respiratory tract, and central nervous system in infants, especially in prematures. We report the first case of U. urealyticum meningitis in a premature infant in Korea. She was born with a birth weight of 1,481 gram at 32+3 weeks' gestation and hospitalized for a respiratory care in the NICU in November 2005. Endotracheal aspirates and urine cultures grew U. urealyticum at <10(4) CFU/mL of the specimens at 2-day-old, and cerebrospinal fluid (CSF) cultures grew U. urealyticum at > or = 10(4) CFU/mL of CSF. The patient had a marked CSF pleocytosis, low glucose and high protein content on the 13th hospital day. CSF cultures for ordinary bacteria, mycobacteria and fungi remained negative. U. urealyticum was resistant to erythromycin, tetracycline, ciprofloxacin and pristinamycin, but susceptible to doxycycline. Although she was treated with erythromycin for 30 days, the organism was still isolated four times from the CSF with fluctuation of C-reactive protein (CRP). After the addition of chloramphenicol, CSF cultures became negative in 3 days. However, CRP rose again with increased BUN at the 99th hospital day, and she died on the 103rd hospital day under the diagnosis of a clinical sepsis of unknown origin. In acute meningitis of prematures already colonized with U. urealyticum, ureaplasmal cultures and susceptibility test are warranted in Korea.

[A case of bacteremia by Atopobium rimae in a patient with liver cirrhosis].

Atopobium rimae, previously Lactobacillus rimae, is a strictly anaerobic, non-spore forming grampositive rod which was frequently isolated from odontogenic infection. We report a case of A. rimae bacteremia. A 47-yr-old man with liver cirrhosis was admitted to the hospital via emergency room due to fever and chill. His abdominal and pelvic computed tomography revealed a small abscess near the left adrenal gland. Three sets of blood cultures were taken and non-spore forming, grampositive rods were detected in all anaerobic vials. This isolate grew small nonhemolytic, gray-white translucent colonies on Brucella blood agar and was obligatory anaerobic on air-tolerance test. This organism was negative for catalase, indole, nitrate-reduction and beta-lactamase and failed to identify by Vitek ANI card (bioMerieux, France). 16S rRNA sequences of this showed 99.8% homology of the published sequence of A. rimae (GenBank accession number AF292371). Aspirates of periadrenal abscess grew Escherichia coli and Peptostreptococcus micros. He was treated with metronidazole and imipenem and follow-up cultures of blood were negative at days 4 and 10. To our knowledge, this is the first report of bacteremia of A. rimae.

Helicobacter pylori infection activates NF-kappaB signaling pathway to induce iNOS and protect human gastric epithelial cells from apoptosis.

Helicobacter pylori infection induces apoptosis and inducible nitric oxide synthase (iNOS) expression in gastric epithelial cells. In this study, we investigated the effects of NF-kappaB activation and iNOS expression on apoptosis in H. pylori-infected gastric epithelial cells. The suppression of NF-kappaB significantly increased caspase-3 activity and apoptosis in H. pylori-infected MKN-45 and Hs746T gastric epithelial cell lines as well as primary gastric epithelial cells. An NF-kappaB signaling pathway via NF-kappaB-inducing kinase and IkappaB kinase-beta activation was found to be involved in the inhibition of apoptosis in H. pylori-infected gastric epithelial cells. In gastric epithelial cells transfected with retrovirus containing IkappaBalpha superrepressor, iNOS mRNA and protein levels were reduced, indicating that H. pylori infection induced the expression of iNOS by activating NF-kappaB. Moreover, a NO donor, S-nitroso-N-acetylpenicillamine (100 microM), decreased caspase-3 activity and apoptosis in NF-kappaB-suppressed cells infected with H. pylori. These results suggest that NF-kappaB activation may play a role in protecting gastric epithelial cells from H. pylori-induced apoptosis by upregulating endogenous iNOS.

Brain tumor invasion model system using organotypic brain-slice culture as an alternative to in vivo model.

PURPOSE: The primary cause of local recurrence and therapeutic failure in the treatment of malignant gliomas is the invasion of tumor cells into the surrounding normal brain. While it is known that malignant gliomas infiltrate diffusely into regions of normal brain, it is frequently very difficult to unequivocally identify the solitary invading glioma cell in histopathological preparations, or in experimental glioma models. We have developed an experimental invasion assay system, which allows us to track the solitary invasive glioma cell, using human brain tissue obtained from routine craniotomies for seizures or trauma. METHODS: This tissue is cut into 1-mm thick slices and cultured in the upper chamber of Transwell culture dishes on top of a 0.4- micro m pore size polyester membrane, which is fed on medium provided in the lower chamber. Glioma cells are stably transfected with vectors containing a green fluorescent protein (GFP) cDNA. Stable, high-level expression GFP transfectants were selected by direct visualization under fluorescence microscope. In addition, various tumor spheroids are stained with vital dye, DiI, to track the invading cells. GFP-expressing glioma cells or stained spheroids were then implanted on the center of the brain slice, and the degree of brain tumor invasion into the brain tissue was evaluated at different time points by optical sectioning using a confocal microscope. RESULTS: We observed that GFP-expressing glioma cells or stained spheroids could be readily tracked and followed with this model system. Individual tumor cells that exhibited green or red fluorescence could be identified and their migration path through the brain slices unequivocally followed. CONCLUSION: This experimental invasion system may be of considerable utility in studying the process of brain tumor invasion and in evaluating its invasiveness in individual brain tumor because it not only provides a better representation of extracellular matrix molecules normally encountered by invading glioma cells, but also provides the fluorescent tag applied to the tumor cells.