Katarzyna Wejksza

Betulinic acid decreases expression of bcl-2 and cyclin D1, inhibits proliferation, migration and induces apoptosis in cancer cells

Betulinic acid (BA) is a pentacyclic triterpene found in many plant species, among others in the bark of white birch Betula alba. BA was reported to display a wide range of biological effects, including antiviral, antiparasitic, antibacterial and anti-inflammatory activities, and in particular to inhibit growth of cancer cells. The aim of the study was further in vitro characterization of BA anticancer activity. In this study, we demonstrated a remarkable antiproliferative effect of BA in all tested tumor cell cultures including neuroblastoma, rabdomyosarcoma-medulloblastoma, glioma, thyroid, breast, lung and colon carcinoma, leukemia and multiple myeloma, as well as in primary cultures isolated from ovarian carcinoma, cervical carcinoma and glioblastoma multiforme. Furthermore, we have shown that BA decreased cancer cell motility and induced apoptotic cell death. We also observed decrease of bcl2 and cyclin D1 genes expression, and increase of bax gene expression after betulinic acid treatment. These findings demonstrate the anticancer potential of betulinic acid and suggest that it may be taken into account as a supportive agent in the treatment of cancers with different tissue origin.

Demonstration of kynurenine aminotransferases I and II and characterization of kynurenic acid synthesis in cultured cerebral cortical neurons

The present study characterizes the synthesis of kynurenic acid (KYNA) from exogenously added kynurenine and its regulation by extrinsic factors, in cultured cerebral cortical neurons and, for comparison, in astrocytes incubated under identical conditions. The neuronal culture showed positive immunostaining for both kynurenic acid aminotransferase (KAT) isoforms I and II. Neurons synthesized KYNA at a rate about 2.3 times higher than astrocytes. Neuronal, but not astrocytic, KYNA synthesis was lowered ∼30% by ionotropic glutamate receptor agonists [(R,S)‐3‐hydroxy‐5‐methoxyloxasole‐4‐propionic acid (AMPA; 100 μM) and N‐methyl‐D‐aspartic acid (NMDA; 100 μM)] and depolarizing agents [KCl (50 mM) and 4‐aminopyridine (4‐AP; 10 μM)]. Neuronal and astrocytic synthesis alike were vulnerable to inhibition exerted by the aminotransferase inhibitor aminooxyacetic acid (AOAA), glutamate (IC50: 31 and 85 μM, respectively), substrates of the L‐amino transport system [leucine (Leu); IC50: 19 and 42 μM, respectively] and 2‐aminobicyclo[2,2,1]heptane‐2‐carboxylic acid (BCH; IC50: 19 and 28 μM, respectively). Glutamine (Gln), which is a metabolic precursor of glutamate in astrocytes and L‐system substrate in both cell types, inhibited KYNA synthesis both in neurons and in astrocytes (IC50: 268 and 318 μM, respectively). α‐Ketoisocaproic acid (KIC), a Leu transamination product that is produced mainly in astrocytes and shuttled to neurons to modulate intraneuronal concentration of glutamate, stimulated KYNA synthesis in neurons but did not affect the synthesis in astrocytes. In conclusion, this study is the first to demonstrate active, regulation‐prone KYNA synthesis in neurons.

Kynurenic acid protects against the homo-cysteine-induced impairment of endothelial cells

Kynurenic acid (KYNA) is a tryptophan metabolite produced in the kynurenine pathway. In the central nervous system, KYNA exerts neuroprotective and anticonvulsant effects by mechanisms associated with its antagonist activity against the ionotropic glutamate and alpha-7 nicotinic receptors. Its presence has been documented not only in cerebrospinal fluid and brain tissue, but also in the periphery. However, KYNAs function outside the brain has not been fully elucidated. In this study, experiments performed on bovine aorta endothelial cell cultures showed for the first time that KYNA exerts a protective activity against the homocysteine-induced impairment of endothelial cells. The addition of KYNA significantly increased endothelial cell migration and proliferation, which is diminished by homocysteine. KYNA also protected cells against homocysteine-induced cytotoxicity. Our data suggest that increasing KYNA levels in blood vessels may have a significant impact on the endothelium in hyperhomocysteinemia.

Kynurenic acid production in cultured bovine aortic endothelial cells. Homocysteine is a potent inhibitor.

Kynurenic acid (KYNA) is a broad-spectrum antagonist at all subtypes of ionotropic glutamate receptors, but is preferentially active at the strychnine-insensitive glycine allosteric site of the N-methyl-d-aspartate (NMDA) receptor and is also a non-competitive antagonist at the alpha7 nicotinic receptor. KYNA occurs in the CNS, urine, serum and amniotic fluid. Whilst it possesses anticonvulsant and neuroprotective properties in the brain, its role in the periphery, however, is unknown. In this study we demonstrated the presence of kynurenine aminotransferase (KAT) I and II in the cytoplasm of bovine aortic endothelial cells (BAEC). BAEC incubated in the presence of the KYNA precursor l-kynurenine synthesized KYNA concentration- and time-dependently. KYNA production was inhibited by the aminotransferase inhibitor aminooxyacetic acid but was not affected by a depolarising concentration of K+ or by 4-aminopyridine. The glutamate agonists l-aspartate and l-glutamate depressed KYNA production significantly. The selective ionotropic glutamate receptor agonists α-amino-2,3-dihydro-5-methyl-3-oxo-4-isoxazolepropionic acid (AMPA) and NMDA were ineffective in this respect. d,l-Homocysteine and l-homocysteine sulphinic acid lowered KYNA production in BAEC. Further investigations are needed to assess the role and importance of KYNA in vessels and peripheral tissues.

Kynurenic acid in blood and bone marrow plasma of monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) patients.

Increased levels of kynurenic acid (KYNA) have been detected in patients with neurological, autoimmune and tumor diseases. The aim of this paper was to determine KYNA levels in the blood and bone marrow plasma of MGUS and MM patients and to find out common events which are characteristic for both pathological stages and correlates with diagnostic markers of MGUS and MM. We also examined whether bone marrow stromal cells (BMSCs) and MM cells could produce KYNA. The levels of KYNA present in plasma and in cell culture media were examined by HPLC. An increased level of KYNA was detected in the blood and marrow plasma of MGUS patients and in the blood plasma of the MM group. In the MM group, the blood KYNA level was the highest in patients with monoclonal IgG protein and with free light chains of immunoglobulins and correlated positively with blood levels of creatinine and urea. In the MGUS group, KYNA correlated positively with the C-reactive protein (CRP) level, and in both groups KYNA correlated positively with the beta2-microglobulin. We detected KYNA production in BMSCs of control and MM patients and by two myeloma cell lines used in the experiments. The results suggest that the increased KYNA level in MGUS patients was mainly caused by a dysfunction of the immune system, as it correlated positively with CRP and beta2-microglobulin levels. In MM patients, the increased KYNA level may have been a result of a dysfunction of the immune system, KYNA production by myeloma cells, and decreased KYNA excretion by kidneys.

Wtórne nowotwory u chorych z nadpłytkowością samoistną leczonych w Klinice Hematoonkologii i Transplantacji Szpiku UM w Lublinie

STRESZCZENIE Nadplytkowośc samoistna (ET; essential thrombocythemia) nalezy do przewleklych chorob mieloproliferacyjnych i ma na ogol malo agresywny przebieg, jednak czas przezycia chorych jest krotszy w porownaniu z ogolną populacją. Do niedawna za glowne przyczyny skrocenia czasu zycia chorych uznawano zaawansowany wiek i przebyte epizody zakrzepowe. Obecnie coraz wiecej uwagi zwraca sie na inny powod, jakim jest rozwoj u tych chorych wtornych nowotworow niehematologicznych.