Genetic factors predisposing to the development of papillary thyroid cancer

According to classic theory of neogenesis, cancer arises from well-differentiated cell that in response to variety of factors de-differentiates, becomes able to proliferate without control and/or loses its ability to undergo apoptosis. According to another theory, cancers (at least cancers of some organs) originate from stem cells, which "by definition" are poorly differentiated and able to proliferate indefinitely. Therefore a lower number of abnormal events is necessary for these cells to escape proliferation-controlling mechanisms. With regard to papillary thyroid cancers it is still thought that it arises from well-differentiated thyreocyte. One of the characteristic features of cancer cell is chromosomal instability. Lowest number of such abnormalities is observed in well-differentiated thyroid cancers (including papillary cancer), intermediate - in poorly-differentiated cancers, while highest - in anaplastic cancers. Microarray analysis shows that despite of clinical heterogeneity, gene expression profiles of papillary cancers are very similar. Genetic anomalies predisposing to the development of papillary cancer most commonly regard proteins that possess kinase activity. Kinases phosphorylate other proteins, and play an extremely important role in signal transduction from outside the cell as well as inside the cell. Constitutive activation of some kinases may lead to the excessive and/or permanent activation of some transduction pathways specific for mitogens or growth factors. This results in excessive proliferation. The best known protein of such type which function is altered in papillary thyroid cancers is RET - a membrane-located growth factor-receptor with kinase activity. RET gene undergoes different rearrangements in this type of cancer. There are approximately 10 RET rearrangements known, with RET/PTC3 and RET/PTC1 being most common. In this anomaly kinase domain-encoding 3' end of RET gene is aberrantly bound to 5' end of another gene. Fusion protein synthesized on such hybrid template is not present in the cell membrane but in the cytoplasm, where it permanently activates transduction pathway specific for RET. NTRK1 gene encoding a member of family of neuronal growth factor receptors containing thyrosine kinase domain is also rearranged in papillary cancers. However, genes fused to its kinase domain-encoding sequence are different from the ones fused to RET. MET, a gene encoding another membrane protein with thyrosine kinase activity, which acts as a growth factor-receptor, is overexpressed in 70%-90% of papillary thyroid cancers. BRAF gene encoding another yet kinase transducing signals from RAS and RAF to the cell is mutated at position 1796 (T/A, amino acid substitution V599E) in 38-69% of papillary cancers. The presence of this activatory mutation is associated with higher degree of clinical advancement of the disease. In addition, in majority of papillary cancers tested, mutations of the genes encoding nuclear triiodothyronine receptors were found. Transgenic mice with both TRB allele replaced with dominant-negative TRB mutants develop aggressive thyroid cancers. Progression from papillary to anaplastic cancer is most possibly caused by the occurrence of additional anomalies within P53, RAS, NM23,b-catenin gene and other genes.     

Glutathione S-transferase pi as a target for tricyclic antidepressants in human brain

GST pi, the main glutathione S-transferase isoform present in the human brain, was isolated from various regions of the brain and the in vitro effect of tricyclic antidepressants on its activity was studied. The results indicated that amitripyline and doxepin - derivatives of dibenzcycloheptadiene, as well as imipramine and clomipramine - derivatives of dibenzazepine, inhibit the activity of GST pi from frontal and parietal cortex, hippocampus and brain stem. All these tricyclics are noncompetitive inhibitors of the enzyme with respect to reduced glutathione and noncompetitive (amitripyline, doxepin) or uncompetitive (imipramine, clomipramine) with respect to the electrophilic substrate. Their inhibitory effect is reversible and it depends on the chemical structure of the tricyclic antidepressants rather than on the brain localization of the enzyme. We conclude that the interaction between GST pi and the drugs may reduce their availability in the brain and thus affect their therapeutic activity. On the other hand, tricyclic antidepressants may decrease the efficiency of the enzymatic barrier formed by GST and increase the exposure of brain to toxic electrophiles. Reactive electrophiles not inactivated by GST may contribute in adverse effects caused by these drugs.     

A simple method for selection of trypsin chromogenic substrates using combinatorial chemistry approach

A tetrapeptide combinatorial library, considered as chromogenic substrates of bovine beta-trypsin, was synthesized by the solid phase method. The peptides contain an analog of p-nitroanilide, obtained by attaching 5-amino-2-nitrobenzoic acid (Anb(5,2)) to the C-termini. Deconvolution of the peptide library, performed in solution using an iterative method, yielded four efficient trypsin substrates. The most active one, Phe-Val-Pro-Arg-Anb(5,2)-NH(2), appeared to be 125-fold more active than Bz-D,L-Arg-pNA (BAPNA) used as a reference compound. The reported method of designing trypsin chromogenic substrate libraries is straightforward. Such p-nitroanilides may be useful for the investigation of any protease substrate specificity.     

Arginase as a useful factor for the diagnosis of colorectal cancer liver metastases

The present work is a continuation of studies on arginase as a marker in the diagnosis of colorectal cancer liver metastases (CRCLM). The purpose of the study was the evaluation of the arginase test in comparison with other colorectal cancer tests such as CEA, CA 19-9 and biochemical markers of liver function such as aspartate aminotransferase (AST) and alanine aminotransferase (ALT). The studies were conducted on blood serum from 85 patients with CRCLM obtained one to two days before tumor resection. The control group comprised 140 healthy blood donors and 81 patients with various non-malignant gastrointestinal diseases. Raised arginase activity was observed in serum of 85% of CRCLM patients, whereas elevated levels of CEA and CA 19-9 were found in 63% and 42% of patients, respectively. The combination of CEA or CA 19-9 with the arginase assay improved their sensitivity, but the sensitivity of the combined parameters was not higher than that of the arginase test itself. AST and ALT activities were increased in about 30% of CRCLM patients. The specificity of the arginase test calculated for 221 control subjects was 76%. It can thus be concluded that the determination of serum arginase activity can be helpful in the diagnosis of patients with colorectal cancer liver metastases.     

Cargo selection by specific kinesin light chain 1 isoforms

Kinesin-1 drives the movement of diverse cargoes, and it has been proposed that specific kinesin light chain (KLC) isoforms target kinesin-1 to these different structures. Here, we test this hypothesis using two in vitro motility assays, which reconstitute the movement of rough endoplasmic reticulum (RER) and vesicles present in a Golgi membrane fraction. We generated GST-tagged fusion proteins of KLC1B and KLC1D that included the tetratricopeptide repeat domain and the variable C-terminus. We find that preincubation of RER with KLC1B inhibits RER motility, whereas KLC1D does not. In contrast, Golgi fraction vesicle movement is inhibited by KLC1D but not KLC1B reagents. Both RER and vesicle movement is inhibited by preincubation with the GST-tagged C-terminal domain of ubiquitous kinesin heavy chain (uKHC), which binds to the N-terminal domain of uKHC and alters its interaction with microtubules. We propose that although the TRR domains are required for cargo binding, it is the variable C-terminal region of KLCs that are vital for targeting kinesin-1 to different cellular structures.     

Transferrin conjugates in the anticancer therapy

To enhance the therapeutic efficiacy of anticancer drugs and reducing its systemic side-effects carriers are used. Transferrin is one of the very promising protein which can be used to transport drugs, DNA and ions into the cancer cells. Because of the fact that neoplastic cells have increased number of transferrin receptors, the transferrin can deliver the drugs directly to the neoplastic cells without injury of normal cells.     

Effects of exogenous nitric oxide on the antioxidant capacity of cadmium-treated soybean cell suspension

Nitric oxide (NO) is a small, ubiquitous molecule, whose physiological function in plants has recently been widely investigated. It seems that one of its pivotal properties is the antioxidant capacity, enabling plants to alleviate the effects of the oxidized stress. In this work we investigated the role of NO in soybean (Glycine max L. Cv. Navico) cell suspension treated with cadmium. Sodium nitroprusside (SNP), nitric oxide donor, markedly decreased the negative influence of Cd²⁺ on cell growth. It was also found to stimulate superoxide dismutase (SOD, EC 1.15.1.1). Using specific fluorochromes — dihydroethidine (DHE) and 2′,7′- dichlorofluorescein (DCFH-DA) it was shown that NO was very effective in reducing the level of superoxide anion (O ₂ ^·− ) and hydrogen peroxide, respectively. Furthermore, as evaluated by means of NO specific fluorochrome 4,5-diaminofluorescein diacetate (DAF-2DA), increased production of NO was found in Cd-treated cells. In cadmium-stressed cells SNP lowered the level of oxidized proteins. Our results suggest that the antioxidant properties of nitric oxide in Cd-treated soybean cells rely mainly on its ability to direct scavenging of ROS and stimulation of the antioxidant system.     

Borrelia burgdorferi sensu lato infection in mosquitoes from Szczecin area

The aim of the study was to determine the level of infection in mosquitoes with spirochetes Borrelia burgdorferi sensu lato in the woody areas of Szczecin. The mosquitoes were collected from May to September 2003. The spirochetes, Borrelia burgdorferi s. l., present in mosquitoes were detected in mosquitoes with indirect immunofluorescence assay (IFA) using rabbit anti-Borrelia burgdorferi antibodies and goat anti-rabbit IgG marked with fluorescein isocyanate (FITC). A total of 1557 females and 58 males were collected. They represented the genera Aedes (63%) and Culex (37%). The infection level of the mosquitoes from the area studied amounted to 1.7%. The results of the present study confirm the potential of these arthropods to spread Lyme borreliosis.