Silencing of ABCG2 by MicroRNA-3163 Inhibits Multidrug Resistance in Retinoblastoma Cancer Stem Cells

To investigate the function and regulation mechanism of ATP-binding cassette, subfamily G, member 2 (ABCG2) in retinoblastoma cancer stem cells (RCSCs), a long-term culture of RCSCs from WERI-Rb1 cell line was successfully established based on the high expression level of ABCG2 on the surface of RCSCs. To further explore the molecular mechanism of ABCG2 on RCSCs, a microRNA that specifically targets ABCG2 was predicted. Subsequently, miR-3163 was selected and confirmed as the ABCG2-regulating microRNA. Overexpression of miR-3163 led to a significant decrease in ABCG2 expression. Additionally, ABCG2 loss-of-function induced anti-proliferation and apoptosis-promoting functions in RCSCs, and multidrug resistance to cisplatin, carboplatin, vincristine, doxorubicin, and etoposide was greatly improved in these cells. Our data suggest that miR-3163 has a significant impact on ABCG2 expression and can influence proliferation, apoptosis, and drug resistance in RCSCs. This work may provide new therapeutic targets for retinoblastoma.

Leishmania amazonensis exhibits phosphatidylserine-dependent procoagulant activity, a process that is counteracted by sandfly saliva

Leishmania parasites expose phosphatidylserine (PS) on their surface, a process that has been associated with regulation of host's immune responses. In this study we demonstrate that PS exposure by metacyclic promastigotes of Leishmania amazonensis favours blood coagulation. L. amazonensis accelerates in vitro coagulation of human plasma. In addition, L. amazonensis supports the assembly of the prothrombinase complex, thus promoting thrombin formation. This process was reversed by annexin V which blocks PS binding sites. During blood meal, Lutzomyia longipalpis sandfly inject saliva in the bite site, which has a series of pharmacologically active compounds that inhibit blood coagulation. Since saliva and parasites are co-injected in the host during natural transmission, we evaluated the anticoagulant properties of sandfly saliva in counteracting the procoagulant activity of L. amazonensis . Lu. longipalpis saliva reverses plasma clotting promoted by promastigotes. It also inhibits thrombin formation by the prothrombinase complex assembled either in phosphatidylcholine (PC)/PS vesicles or in L. amazonensis . Sandfly saliva inhibits factor X activation by the intrinsic tenase complex assembled on PC/PS vesicles and blocks factor Xa catalytic activity. Altogether our results show that metacyclic promastigotes of L. amazonensis are procoagulant due to PS exposure. Notably, this effect is efficiently counteracted by sandfly saliva.

The role of the cell adhesion molecules (integrins / cadherins) in prostate cancer

During prostate carcinogenesis the cellular adhesion molecules, i.e.; integrins and cadherins mediate aberrant interactions between glandular epithelial cells and the extracellular matrix. Several integrin α subunits are down-regulated, while β subunits are up-regulated. The expression of several cadherins and catenins has specific prognostic value. There is an association between the expression of the E-cadherin/catenin complex and high grade prostate cancer. Clinical trials evaluating the efficacy of integrin antagonists are ongoing with promising results. In this article we update the role of integrins and cadherins in prostate carcinogenesis and evaluate the therapeutic potential of their manipulation.

Anti-tumor mechanisms and regulation of survivin by selective cyclooxygenase-2 inhibitor / 대한간학회지

No abstract available.

Down-regulation of survivin in growth inhibition of hepatoma cells induced by a selective cyclooxygenase-2 inhibitor / 대한간학회지

BACKGROUND/AIMS: Cyclooxygenase-2 (COX-2) inhibitors reportedly inhibit the growth of hepatocellular carcinoma (HCC) via caspase-dependent or caspase-independent apoptosis, which is due to COX-2 being associated with hepatocarcinogenesis. Survivin is highly expressed in most human cancers, but the mechanism regulating survivin expression remains unclear. We investigated the regulatory expression of survivin in selective-COX-2-inhibitor-induced growth inhibition of hepatoma cells. METHODS: After treatment with NS-398 (a selective COX-2 inhibitor) at various concentrations (10, 50, 100, 150, and 200 micrometer), the growth inhibition of Hep3B hepatoma cells was assessed by an MTT cell-viability assay, DNA fragmentation gel analysis, and flow cytometry. The expression of survivin transcript was analyzed by reverse-transcription polymerase chain reactions. RESULTS: NS-398 inhibited the growth of hepatoma cells by an amount dependent on the concentration and the time since treatment. Apoptotic DNA ladder and flow-cytometry shifting to the sub-G1 phase were revealed in NS-398-induced growth inhibition of hepatoma cells. NS-398 suppressed the expression of the survivin gene in a concentration- and time-dependent manner. CONCLUSIONS: Survivin was down-regulated in the growth inhibition of hepatoma cells induced by a selective COX-2 inhibitor, NS-398, in a concentration- and time-dependent manner. These results suggest the therapeutic inhibition of COX-2 via suppression of survivin in HCC.

Specific inhibition of the expression of the promyelocytic leukemia [PML] protien by anti-sense oligonucleotides

In the present study, using anti-sense oligonucleotides the inhibition of expression of the PML protein has been investigated. The anti-sense oligonucleotides were designed against the translation initiation site of the PML gene, and their effects were investigated on cellular growth and DNA synthesis. Incubation of normal human fibroblast cells with the anti-sense oligonucleotides resulted in the complete inhibition of the PML protein expression. Inhibition of the PML protein expression by anti-sense oligonucleotides was found to be associated with an increase in cellular growth and doubling time. Furthermore, in cells treated with the anti-sense oligonucleotides, but not sense or scrambled oligonucleotides [control], the cellular DNA synthesis also showed a marked increase, confirming the induction of cellular growth upon inhibition of PML synthesis. These findings clearly demonstrated that the inhibition of the expression of the PML protein could be achieved using the anti-sense oligonucleotides, providing a model for better investigation of the biologic role of PML in the cell

La telomerasa: una enzima con múltiples aplicaciones en la investigación del cáncer / Telomerase: an enzyme with multiple applications in cancer research

The telomerase is a ribonucleoprotein enzyme to which multiple functions have been attributed, the most important of these is the maintenance of the telomere which is related with cellular immortalization and cancer. 85 of human tumors have telomerase activity, that in normal cells goes undetected. These characteristics make the telomerase an attractive target for chemotherapy.