Diversity of the Rysto gene conferring resistance to potato virus Y in wild relatives of potato.

BACKGROUND: Potato virus Y (PVY) is among the economically most damaging viral pathogen in production of potato (Solanum tuberosum) worldwide. The gene Rysto derived from the wild potato relative Solanum stoloniferum confers extreme resistance to PVY. RESULTS: The presence and diversity of Rysto were investigated in wild relatives of potato (298 genotypes representing 29 accessions of 26 tuber-bearing Solanum species) using PacBio amplicon sequencing. A total of 55 unique Rysto-like sequences were identified in 72 genotypes representing 12 accessions of 10 Solanum species and six resistant controls (potato cultivars Alicja, Bzura, Hinga, Nimfy, White Lady and breeding line PW363). The 55 Rysto-like sequences showed 89.87 to 99.98% nucleotide identity to the Rysto reference gene, and these encoded in total 45 unique protein sequences. While Rysto-like26 identified in Alicja, Bzura, White Lady and Rysto-like16 in PW363 encode a protein identical to the Rysto reference, the remaining 44 predicted Rysto-like proteins were 65.93 to 99.92% identical to the reference. Higher levels of diversity of the Rysto-like sequences were found in the wild relatives of potato than in the resistant control cultivars. The TIR and NB-ARC domains were the most conserved within the Rysto-like proteins, while the LRR and C-JID domains were more variable. Several Solanum species, including S. antipoviczii and S. hougasii, showed resistance to PVY. This study demonstrated Hyoscyamus niger, a Solanaceae species distantly related to Solanum, as a host of PVY. CONCLUSIONS: The new Rysto-like variants and the identified PVY resistant potato genotypes are potential resistance sources against PVY in potato breeding. Identification of H. niger as a host for PVY is important for cultivation of this plant, studies on the PVY management, its ecology, and migrations. The amplicon sequencing based on PacBio SMRT and the following data analysis pipeline described in our work may be applied to obtain the nucleotide sequences and analyze any full-length genes from any, even polyploid, organisms.

New Meloxicam Derivatives-Synthesis and Interaction with Phospholipid Bilayers Measured by Differential Scanning Calorimetry and Fluorescence Spectroscopy.

The purpose of the present paper was to assess the ability of five newly designed and synthesized meloxicam analogues to interact with phospholipid bilayers. Calorimetric and fluorescence spectroscopic measurements revealed that, depending on the details of the chemical structure, the studied compounds penetrated bilayers and affected mainly their polar/apolar regions, closer to the surface of the model membrane. The influence of meloxicam analogues on the thermotropic properties of DPPC bilayers was clearly visible because these compounds reduced the temperature and cooperativity of the main phospholipid phase transition. Additionally, the studied compounds quenched the fluorescence of prodan to a higher extent than laurdan, what pointed to a more pronounced interaction with membrane segments close to its surface. We presume that a more pronounced intercalation of the studied compounds into the phospholipid bilayer may be related to the presence of the molecule of a two-carbon aliphatic linker with a carbonyl group and fluorine substituent/trifluoromethyl group (compounds PR25 and PR49) or the three-carbon linker together with the trifluoromethyl group (PR50). Moreover, computational investigations of the ADMET properties have shown that the new meloxicam analogues are characterized by beneficial expected physicochemical parameters, so we may presume that they will have a good bioavailability after an oral administration.

Evaluation of reference genes for miRNA and mRNA normalization in tobacco infected with PVYNTN, PVYN-Wi and PVYZ-NTN strains.

This is the first report on identification of the most suitable reference genes for RT-qPCR quantification of miRNA and mRNA in tobacco response to the prevalent recombinant potato virus Y (PVY) strains PVYNTN, PVYN-Wi and the newly identified PVYZ-NTN. Of 10 tested genes, the expression levels of neIF5C, nU2af and nPP2A were the most stable in samples taken from non-inoculated, mock-inoculated, and infected plants at three days post-inoculation (dpi) and 14 dpi. While the homologues of eIF5 were most stably expressed in tobacco in this study and in potato in our previous study (Yin et al., 2021) following inoculation with the same three PVY strains, the homologues of other two genes PP2A and U2af were stably expressed only in tobacco but unstable in potato. The tobacco homologue of PP2A, which was the most stably expressed one in tobacco interaction with PVYNTN, PVYN-Wi and PVYZ-NTN strains in this study, was the least stable one in tobacco interaction with the non-recombinant PVYO strain in a previous study (Baek et al., 2017). This study provides evidence on the influence of host species on expression of housekeeping genes and points out virus strain as a new factor influencing expression stability of reference gene. Caution should be taken when choosing reference genes in gene expression study in Solanaceae hosts response to different PVY strains.

Interaction of Oxicam Derivatives with the Artificial Models of Biological Membranes-Calorimetric and Fluorescence Spectroscopic Study.

The modified 1,2-benzothiazine analogues designed as new drug candidates and discussed in this paper are oxicam derivatives. Oxicams are a class of non-steroidal anti-inflammatory drugs (NSAIDs). Their biological target is cyclooxygenase (COX), a membrane protein associated with the phospholipid bilayer. In recent decades, it has been proven that the biological effect of NSAIDs may be closely related to their interaction at the level of the biological membrane. These processes are often complicated and the biological membranes themselves are very complex. Therefore, to study these mechanisms, simplified models of biological membranes are used. To characterize the interaction of six oxicam derivatives with DPPC, DMPC and EYPC, artificial models of biological membranes (multi-bilayers or liposomes), differential scanning calorimetry (DSC) and fluorescence spectroscopy techniques were applied. In spectroscopic measurements, two fluorescent probes (Laurdan and Prodan) localized in different membrane segments were used. All tested oxicam derivatives interacted with the lipid bilayers and may penetrate the artificial models of biological membranes. They intercalated into the lipid bilayers and were located in the vicinity of the polar/apolar membrane interface. Moreover, a good drug candidate should not only have high efficiency against a molecular target but also exhibit strictly defined ADMET parameters, therefore these activities of the studied compounds were also estimated.

Statins as inhibitors of voltage-gated potassium channels Kv1.3 in cancer cells.

Voltage-gated potassium channels are integral membrane proteins selectively permeable for potassium ions and activated upon change of membrane potential. Voltage-gated potassium channels of the Kv1.3 type were discovered both in plasma membrane and in inner mitochondrial membrane (mito Kv1.3 channels). For some time Kv1.3 channels located both in plasma membrane and in mitochondria are considered as a potentially new molecular target in several pathologies including some cancer disorders. Lipophilic nontoxic organic inhibitors of Kv1.3 channels may potentially find a clinical application to support therapy of some cancer diseases such as breast, pancreas and lung cancer, melanoma or chronic lymphocytic leukaemia (B-CLL). Inhibition of T lymphocyte Kv1.3 channels may be also important in treatment of chronic and acute respiratory diseases including severe pulmonary complication in corona virus disease Covid 19, however further studies are needed to confirm this supposition. Statins are small-molecule organic compounds, which are lipophilic and are widely used in treatment of hypercholesterolemia and atherosclerosis. Electrophysiological studies performed in our laboratory showed that statins: pravastatin, mevastatin and simvastatin are effective inhibitors of Kv1.3 channels in cancer cells of human T cell line Jurkat. We showed that application of the statins in the concentration range from 1.5 µM to 50 µM inhibited the channels in a concentration-dependent manner. The inhibitory effect was the most potent in case of simvastatin and the least potent in case of pravastatin. The inhibition was partially irreversible in case of simvastatin and fully reversible in case of pravastatin and mevastatin. It was accompanied by a significant acceleration of the current inactivation rate without any significant change of the activation rate. Mechanism of the inhibition is probably complex, including a direct interaction with the channel protein and perturbation of lipid bilayer structure, leading to stabilization of the inactivated state of the channels.

Reference gene selection for miRNA and mRNA normalization in potato in response to potato virus Y.

This was the first report on evaluating candidate reference genes for quantifying the expression profiles of both coding (e.g., mRNA) and non-coding (e.g., miRNA) genes in potato response to potato virus Y (PVY) inoculation. The reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR) method was employed to quantify the expression profiles of eight selected candidate reference genes; their expression stability was analyzed by four statistical algorithms, i.e., geNorm, BestKeeper, NormFinder and RefFinder. The most stable reference genes were sEF1a, sTUBb and seIF5 with a high stability. The least stable ones were sPP2A, sSUI1 and sGAPDH. The same reference gene allows for normalization of both miRNA and mRNA levels from a single RNA sample using cDNAs synthesized in a single RT reaction, in which a stem-loop primer was used for miRNAs and the oligo (dT) for mRNAs.

Organosilicon Compounds, SILA-409 and SILA-421, as Doxorubicin Resistance-Reversing Agents in Human Colon Cancer Cells.

Multidrug resistance (MDR) that occurs in cancer cells constitutes one of the major reasons for chemotherapy failure. The main molecular mechanism of MDR is overexpression of protein transporters from the ATP-binding cassette (ABC) superfamily, such as ABCB1 (multidrug resistance protein 1 (MDR1), P-glycoprotein). At the expense of ATP hydrolysis, ABCB1 pumps a diverse range of substrates (including anticancer drugs) out of the cell, thereby reducing their intracellular concentration. In the present study, the ability of two patented disiloxanes (SILA-409 and SILA-421) to reverse drug resistance in human colon adenocarcinoma cell lines LoVo and LoVo/Dx was investigated. It was demonstrated that both compounds in concentrations of 0.5-1 µM strongly increased the sensitivity of LoVo/Dx cells to doxorubicin. By means of an accumulation test in which rhodamine 123 was used as an ABCB1 substrate analogue, both organosilicon compounds were also shown to inhibit ABCB1 transport activity. The intracellular accumulation of doxorubicin was also increased, and more drug entered the cellular nuclei of resistant cells in the presence of the studied compounds. In conclusion, both SILA-409 and SILA-421 were demonstrated to be effective MDR reversal agents in resistant human colon cancer cells.

Voltage-Gated Potassium Channel Kv1.3 as a Target in Therapy of Cancer.

Voltage-gated potassium channel Kv1.3 is an integral membrane protein, which is selectively permeable for potassium ions and is activated upon a change of membrane potential. Channel activation enables transportation of potassium ions down their electrochemical gradient. Kv1.3 channel is expressed in many cell types, both normal and cancer. Activity of the channel plays an important role in cell proliferation and apoptosis. Inhibition of Kv1.3 channel may be beneficial in therapy of several diseases including some cancer disorders. This review focuses on Kv1.3 channel as a new potentially attractive molecular target in cancer therapy. In the first part, changes in the channel expression in selected cancer disorders are described. Then, the role of the channel activity in cancer cell proliferation and apoptosis is presented. Finally, it is shown that some low molecular weight organic inhibitors of the channel including selected biologically active plant-derived polycyclic compounds may selectively induce apoptosis of Kv1.3-expressing cancer cells while sparing normal cells and healthy organs. These compounds may be promising candidates for putative application in therapy of some cancer disorders, such as melanoma, pancreatic ductal adenocarcinoma (PDAC), or B-type chronic lymphocytic leukemia (B-CLL).

The Combined Use of Phenothiazines and Statins Strongly Affects Doxorubicin-Resistance, Apoptosis, and Cox-2 Activity in Colon Cancer Cells.

Since none of the multidrug resistance (MDR) modulators tested so far found their way into clinic, a novel approach to overcome the MDR of cancer cells has been proposed. The combined use of two MDR modulators of dissimilar mechanisms of action was suggested to benefit from the synergy between them. The effect of three phenothiazine derivatives that were used as single agents and in combination with simvastatin on cell growth, apoptosis induction, activity, and expression of cyclooxygenase-2 (COX-2) in doxorubicin-resistant colon cancer cells (LoVo/Dx) was investigated. Treatment of LoVo/Dx cells by phenothiazine derivatives combined with simvastatin resulted in an increase of doxorubicin cytotoxicity and its intracellular accumulation as compared to the treatment with phenothiazine derivatives that were used as single agents. Similarly, LoVo/Dx cells treated with two-component mixture of modulators showed the reduced expression of ABCB1 (P-glycoprotein) transporter and COX-2 enzyme, both on mRNA and protein level. Reduced expression of anti-apoptotic Bcl-2 protein and increased expression of pro-apoptotic Bax were also detected. Additionally, COX-2 activity was diminished, and caspase-3 activity was increased to a higher extent by phenothiazine derivative:simvastatin mixtures than by phenothiazine derivatives themselves. Therefore, the introduction of simvastatin strengthened the anti-MDR, anti-inflammatory, and pro-apoptotic properties of phenothiazines in LoVo/Dx cells.

Cytotoxic and multidrug resistance reversal activity of phenothiazine derivative is strongly enhanced by theobromine, a phytochemical from cocoa.

The idea of the use of anticancer drugs together with a chemosensitizer emerged as the strategy of reversal of multidrug resistance (MDR) of cancer cells expressing ABC proteins many years ago. The approaches relying on the use of a single chemosensitizer have never resulted in a clinical success. Therefore, the application of drug combinations of two or more compounds with different mechanisms of action might be an alternative approach to increase the success rate. In the present study the cytotoxic and NF-κB inhibition potential of the phenothiazine derivative, MAE-TPR, was evaluated. MAE-TPR was demonstrated to be an effective doxorubicin-resistance modulator in human adenocarcinoma cell line LoVo/Dx. In the presence of MAE-TPR cytotoxicity of doxorubicin was elevated, and its intracellular accumulation increased. Strong synergism occurred between MAE-TPR and Dox. MAE-TPR diminished also the expression of ABCB1 transporter (P-glycoprotein) by affecting NF-κB pathway. Theobromine, a phytochemical from cocoa, which was barely active itself, strongly augmented MDR reversal potency of MAE-TPR. The effect of the combination of phenothiazine derivative with theobromine on cancer cells was studied for the first time in the present work. It was concluded that the use of the proposed combination of two modulators might be a promising strategy for MDR reversal since modulators could be used in concentrations much lower than in case of their single application and in that way the risk of intolerable side-effects could be reduced.

Simvastatin Strongly Augments Proapoptotic, Anti-inflammatory and Cytotoxic Activity of Oxicam Derivatives in Doxorubicin-resistant Colon Cancer Cells.

BACKGROUND: Incidence of cancer is still increasing. Chemotherapy is often unsuccessful; moreover, anticancer drugs cause serious side-effects. It is necessary to develop effective agents for combination therapies that would increase antitumor effects of treatment and reduce its side-effects. MATERIALS AND METHODS: Anticancer activity of oxicam derivatives (PR17 and PR18) alone and in combination with simvastatin on doxorubicin-resistant colon cancer cells was studied. Apoptosis was investigated via caspase-3 activation assay as well as via western blot analysis of expression of apoptotic components, B-cell lymphoma 2 protein (BCL2) and BCL2-associated X protein (BAX). Expression and activity of cyclo-oxygenase-2 (COX2) was also assessed. RESULTS: Oxicam derivatives induced apoptosis through a caspase-3-dependent pathway, up-regulated BAX expression, and down-regulated BCL2 expression. Additionally, oxicam derivatives reduced expression and activity of COX2. Effect of oxicam derivatives on these processes was strongly potentiated by simvastatin. CONCLUSION: Oxicam derivatives at low concentrations effectively inhibit growth of cancer cells after co-administration with simvastatin.

microRNA response in potato virus Y infected tobacco shows strain-specificity depending on host and symptom severity.

The present study demonstrates how different potato virus Y (PVY) strains affect the miRNA balance in tobacco cv. Samsun. The two prevalent strains PVYNTN and PVYN-Wi caused severe and mild veinal necrosis (VN) respectively, and the unique PVYZ-NTN strain induced milder vein clearing (VCl) in the upper non-inoculated leaves. A single amino acid polymorphisms (SAPs) I252V and a Q412 to R412 substitution in the HC-Pro cistron of the PVYZ-NTN strain might relate to the loss of VN in tobacco. The abundance of 18 out of the 26 tested miRNAs was increased upon infection by the severe strains PVYNTN and PVYN-Wi. Expression of a group of defense related transcripts were increased accordingly. Two miRNAs, nta-miR6020a-5p and nta-miR6164a/b, which target the TIR-NBS-LRR type resistant TMV N genes involving in signal transduction, might correlate with the PVYNTN and PVYN-Wi induced VN. The down-regulated mRNAs, e.g., RAP2-7 and TOE3, PXC3, LRR-RLK, ATHB-14 and TCP4 targeted by nta-miR172, nta-miR390, nta-miR482, nta-miR166 and nta-miR319/159 respectively, were related to regulation of transcription, protein phosphorylation and cell differentiation. The observed strain-specific alteration of miRNAs and their targets are host dependent and corresponds to the symptom severity and the viral HC-Pro RNA levels.

MDR reversal and pro-apoptotic effects of statins and statins combined with flavonoids in colon cancer cells.

The resistance of cancer cells to a variety of structurally non-related cytotoxic drugs is known as multidrug resistance phenomenon (MDR). In cellular membranes an activity of MDR transporters such as P-glycoprotein (ABCB1) is affected by their lipid environment. Many various compounds have been examined for their ability to restore drug-sensitivity of resistant cancer cells. Statins, inhibitors of the key enzyme of mevalonate pathway HMG-CoA (3-hydroxy-3-methyl-glutaryl-coenzyme A) reductase are drugs commonly prescribed in order to reduce serum level of cholesterol and to diminish the risk of cardiovascular disease. Statins as drugs that influence lipid composition of cell membrane and in that way they also exert influence on lipid bilayer properties appear to be good candidates as MDR modulators. In this work it was shown that statins - mevastatin and simvastatin exert antiproliferative, pro-apoptotic and reversing drug resistance effect in human colon adenocarcinoma cell line LoVo and its drug-resistant subline LoVo/Dx. A hypothesis was also checked whether flavones, which as it is well known are able to influence the biosynthesis of cholesterol, may change the anticancer activity of statins. Our investigations have revealed that combined use of statins and studied flavonoids results in enhanced cell growth inhibition and apoptosis and lower cancer cell proliferation as compared to the application only statins alone. Moreover, in drug resistant LoVo/Dx cells a stronger decrease of resistance to doxorubicine was observed in the presence of statins in combination with flavones as compared to the effect observed for statins only.

The Influence of 6-Prenylnaringenin and Selected Non-prenylated Flavonoids on the Activity of Kv1.3 Channels in Human Jurkat T Cells.

The influence of a prenylated flavonoid-6-prenylnaringenin (6-PR) and selected non-prenylated flavonoids: acacetin, chrysin, baicalein, wogonin, and luteolin on the activity of voltage-gated potassium channels Kv1.3 was investigated in human leukemic Jurkat T cells. Electrophysiological measurements were accompanied by studies on the cytotoxic effect of the examined compounds on Jurkat T cells. Electrophysiological studies were performed using the whole-cell patch-clamp technique. Cell viability was determined using the MTT assay. 6-PR inhibited Kv1.3 channels in Jurkat T cells in a concentration-dependent manner. The estimated value of the half-blocking concentration (EC50) was about 5.76 µM. Among non-prenylated flavonoids, acacetin and chrysin inhibited Kv1.3 channels in Jurkat T cells when applied at the concentration of 30 µM, whereas baicalein, wogonin, and luteolin were ineffective at this concentration. The inhibitory effects of acacetin and chrysin on Kv1.3 channels were significantly less potent than the inhibition caused by 6-PR. All tested compounds inhibited growth of Jurkat T cells in a concentration-dependent manner. Wogonin and chrysin were the most cytotoxic flavonoids tested, whereas baicalein and 6-PR were the least cytotoxic compounds. In accordance to our hypothesis the prenylated flavonoid (6-PR) was much more effective inhibitor of Kv1.3 channels than non-prenylated compounds selected for this study. The inhibition of Kv1.3 channels by 6-PR, acacetin, and chrysin was not related to cytotoxicity of these compounds. The channels' inhibition might be involved in anti-proliferative and pro-apoptotic effects of 6-PR, acacetin and chrysin observed in cancer cell lines expressing these channels.

Increased lipid peroxidation, apoptosis and selective cytotoxicity in colon cancer cell line LoVo and its doxorubicin-resistant subline LoVo/Dx in the presence of newly synthesized phenothiazine derivatives.

Cancer cells often develop the resistance to pro-apoptotic signaling that makes them invulnerable to conventional treatment. Therapeutic strategies that make cancer cells enter the path of apoptosis are desirable due to the avoidance of inflammatory reaction that usually accompanies necrosis. In the present study phenothiazines (fluphenazine and four recently synthesized derivatives) were investigated in order to identify compounds with a potent anticancer activity. Since phenothiazines are known as multidrug resistance modulators the sensitive human colorectal adenocarcinoma cell line (LoVo) and its doxorubicin-resistant, ABCB1 overexpressing, subline (LoVo/Dx) have been employed as a model system. In studied cancer cells cytotoxic effect of the phenothiazine derivatives was accompanied by apoptosis and autophagy induction as well as by the increase of cellular lipid peroxidation and intracellular reactive oxygen species generation. Molecular modelling revealed that reactivity of phenothazines (manifested by their low energy gap) but not lipophilicity was positively correlated with their anticancer potency, pro-oxidant properties and apoptosis induction ability. Additionally, some of the studied compounds turned out to be more potent cytotoxic and pro-apoptotic agents in doxorubicin-resistant (LoVo/Dx) cells than in sensitive ones (LoVo). The hypothesis was assumed that studied phenothiazine derivatives induced apoptotic cell death by increasing the production of reactive oxygen species.

The interaction of new oxicam derivatives with lipid bilayers as measured by calorimetry and fluorescence spectroscopy.

The purpose of the present work was to assess the ability of five new oxicam analogues to interact with the lipid bilayers. To characterize the interaction of newly synthesized NSAIDs (non-steroidal anti-inflammatory drugs) analogues with DPPC lipid bilayers the two following techniques were applied - differential scanning calorimetry (DSC) and fluorescence spectroscopy. The results obtained by these experimental approaches show that new oxicams analogues interact with the lipid model membranes under consideration. As demonstrated both in calorimetric and spectroscopic studies, the greatest influence on the thermotropic properties of the lipid membrane and on the quenching of fluorescence of Laurdan and Prodan was exerted by a derivative named PR47 containing in its structure a two-carbon aliphatic linker with a carbonyl group, as well as bromine and trifluoromethyl substituents.

Anticancer activity of baicalein and luteolin studied in colorectal adenocarcinoma LoVo cells and in drug-resistant LoVo/Dx cells.

Due to the type-specific diversity of cancer cells, an analysis and elucidation of molecular mechanisms responsible for anticancer properties of biologically active compounds are essential. Plant-derived polyphenolic compounds such as flavonoids may be useful in cancer chemoprevention or treatment because they influence diverse molecular pathways in cancer cells. In these studies anticancer activity of natural occurring flavones, baicalein and luteolin was investigated in colon cancer cells LoVo and in their drug resistant subline LoVo/Dx. Inhibitory activity of these flavones on cells growth and their ability to induce apoptosis were observed. A less pronounced influence of studied flavones on proliferation and apoptosis of LoVo/Dx as compared with LoVo cells well correlated with significantly lower cytotoxicity of these compounds in drug-resistant cells. These effects may be related to overexpression of multidrug transporter P-glycoprotein in drug-resistant LoVo/Dx cells. Our studies indicated that baicalein could be a substrate of this drug transporter.

Euphorbia Species-derived Diterpenes and Coumarins as Multidrug Resistance Modulators in Human Colon Carcinoma Cells.

BACKGROUND: Recently, many new potent multidrug resistance (MDR) reversal agents have been discovered, among them lathyrane and jatrophane diterpenes isolated from various Euphorbia species. In the present study, the cytotoxicity, P-glycoprotein inhibition activity, and MDR reversal potency of six diterpenes and two coumarins from two Euphorbia species were studied in human colon carcinoma LoVo cells, and doxorubicin-resistant, LoVo/Dx cells. MATERIALS AND METHODS: Cytotoxicity of the studied compounds (alone and in combination with doxorubicin) was investigated. Inhibition of P-glycoprotein transport activity was monitored by flow cytometry. Changes in intracellular doxorubicin accumulation were observed by means of fluorescence microscopy. RESULTS: Latilagascene B was demonstrated to be an effective P-glycoprotein inhibitor, able to increase doxorubicin accumulation in resistant cells, however not able to restore doxorubicin cytotoxicity in LoVo/Dx cells. CONCLUSION: The structure of latilagascene B seems to be an interesting candidate for further synthesis of new derivatives of reduced cytotoxicity and high anti-MDR potency.

Voltage-Gated Potassium Channels Kv1.3--Potentially New Molecular Target in Cancer Diagnostics and Therapy.

Voltage-gated potassium channels, Kv1.3, which were discovered in 1984, are integral membrane proteins which are activated ("open") upon change of the cell membrane potential, enabling a passive flux of potassium ions across the cell membrane. The channels are expressed in many different tissues, both normal and cancer. Since 2005 it has been known that the channels are expressed not only in the plasma membrane, but also in the inner mitochondrial membrane. The activity of Kv1.3 channels plays an important role, among others, in setting the cell resting membrane potential, cell proliferation, apoptosis and volume regulation. For some years, these channels have been considered a potentially new molecular target in both the diagnostics and therapy of some cancer diseases. This review article focuses on: 1) changes of expression of the channels in cancer disorders with special regard to correlations between the channels' expression and stage of the disease, 2) influence of inhibitors of Kv1.3 channels on proliferation and apoptosis of cancer cells, 3) possible future applications of Kv1.3 channels' inhibitors in therapy of some cancer diseases. In the last section, the results of studies performed in our Laboratory of Bioelectricity on the influence of selected biologically active plant-derived compounds from the groups of flavonoids and stilbenes and their natural and synthetic derivatives on the activity of Kv1.3 channels in normal and cancer cells are reviewed. A possible application of some compounds from these groups to support therapy of cancer diseases, such as breast, colon and lymph node cancer, and melanoma or chronic lymphocytic leukemia (B-CLL), is announced.

Effect of new oxicam derivatives on efflux pumps overexpressed in resistant a human colorectal adenocarcinoma cell line.

BACKGROUND: Oxicams are non-steroidal anti-inflammatory drugs (NSAIDs). Antitumor potential of NSAIDs has often been reported in literature. We studied antitumor activity of newly synthesized oxicam derivatives (PR17 and PR18) against doxorubicin-sensitive and resistant human colorectal adenocarcinoma cells (LoVo and LoVo/Dx). MATERIALS AND METHODS: The cytotoxicity of oxicam derivatives alone and in combination with doxorubicin was assessed. Inhibition of P-glycoprotein (ABCB1) transport activity was monitored by flow cytometry. Expression of ABCB1 gene was analyzed by semi-quantitative reverse transcription PCR, while ABCB1 protein expression was assessed by western blotting. RESULTS: Oxicam derivative PR18 was more cytotoxic to cancer cells than PR17. PR18 was observed to sensitize LoVo/Dx cells to doxorubicin and was identified as an effective multidrug resistance modulator. Additionally, ABCB1 expression was reduced in the presence of PR18. CONCLUSION: PR18 was identified as an effective modulator in LoVo/Dx resistant human colorectal adenocarcinoma cells which overexpressed ABCB1 efflux pump.