The main target of the thesis was to investigate the drug resistance reversal on prokaryotic and eukaryotic model organisms. Based on DNA and protein complex formation properties of the given compounds the plasmid elimination of bacteria and the modification of the drug transporter proteins various experimental systems have been studied in bacteria and tumor cells.It was found that
cells isolated from clinical specimen were less sensitive for the plasmid elimination than the laboratory strain carrying F prime plasmid, however, there was a complex formation between the antiplasmid compounds and the plasmid DNA isolated from both the clinical and laboratory strains. In addition there was a difference between the curing effect of two phenothiazines – the PMZ and TFP – on some
strains in this study. The mechanism of action of different antiplasmid compounds was investigated on model nucleic acids such as calf thymus DNA and plasmid DNA. The pyrido[3,2-g] quinoline and phenothiazine derivatives seemed to have a complex formation with the model nucleic acids. Some of the compounds modified the activity of membrane efflux proteins. Based on the effect of trifluoromethyl ketones earlier studied my attention was focused on the combination of the trifluoromethyl ketone proton pump inhibitor TF18 with well-known antiplasmid compounds such as promethazine, trifluoperazine and 9-aminoacridine. In checkerboard studies the interaction between proton pump inhibitor and tricyclic compounds has been examined and it turned out that the interaction of proton pump inhibitor and trifluoperazine exerted synergistic antibacterial and plasmid curing effect on
doxycycline resistant clinical strain due to the alteration of activity of membrane transporters. The role of proton pump system of the bacterial membrane was studied on
strains. The trifluoroketone proton pump inhibitor was able to block the proton motive forces and the activity of flagellar motor of both clarithromycin sensitive and resistant isolates of
. Since swimming was more sensitive to the inhibition than tumbling, I can suppose that TF18 works as an un-coupler in biological motor. The sensitivity of MDR1 type of eukaryotic ABC-transporter to resistance modifiers was studied on cancer cells. The synthetic benzo[b]-1,8-naphthyridine, pyridoquinoline, aza-oxafluorene and pregnane derivatives exerted reversing action of P-glycoprotein. Furthermore natural compounds, like coumarin derivatives and some fractions of persimmon extracts have been found to be potent resistance reversal agents against tumour cells.
microgravity experiments in tumor research. Several tumor cell lines have shown significant alterations in their properties, including proliferation, apoptosis, and migration ( 6 ). Thyroid cancercells have been shown to be transformed into a less malignant
Milacic V, Banerjee S, Landis-Piwowar KR, Sarkar FH, Majumdar AP, Dou QP: Curcumin inhibits the proteasome activity in human colon cancercells in vitro and in vivo. Cancer Res 68(18), 7283–7292 (2008)
including pcDNA3.1-vector and pcDNA3.1-control were constructed in our lab. LY294002 was bought from Sigma.
Cell culture and transfection
The human breast cell line MCF-10A and breast cancercell line MCF-7
Targeted chemotherapeutics such as cetuximab can cause many side effects such as skin toxicity when used in high concentrations. In addition, cancer cells can develop resistance to some of the anticancer agents during treatment. The lack of the desired success in chemotherapy and the development of resistance to chemotherapeutics, such as epirubicin HCl, suggest that there is a need for combined therapies. The combination of targeted chemotherapeutics and conventional chemotherapy drugs may lead to the emergence of new strategies in the treatment of cancer. In this study, cytotoxic, antiproliferative, cell cycle inhibitive, oxidative stress generation, and apoptotic effects and effect mechanisms of cetuximab alone and together with epirubicin HCl on parental liver cancer cells (P-Hep G2) and epirubicin HCl-resistant liver cancer cells (R-Hep G2) were investigated.
Cytotoxic effects of cetuximab alone and with epirubicin-HCl on cells were determined by Cell Titer-Blue® Cell Viability and Lactate Dehydrogenase Activity tests. Cell cycle distributions and apoptosis were detected by reverse transcription polymerase chain reaction (RT-PCR).
Cetuximab with epirubicin HCl treatment increased the cytotoxic effect on both cells. Caspase-3/7 activity increased 3 and 1.5 times in comparison with control group in P-Hep G2 and R-Hep G2 cells, respectively, after treating with cetuximab alone, whereas the increase was found to be approximately 4.7 and 2.5 times when cetuximab was treated with epirubicin HCl in P-Hep G2 and R-Hep G2 cells, respectively. Both cetuximab alone and together with epirubicin HCl treatments caused increases in Bax/Bcl-2 ratio in both cells.
Treatment of cetuximab with epirubicin HCl to P-Hep G2 and R-Hep G2 cells was found to be more effective in cytotoxic effect and inducing apoptosis comparison to cetuximab alone treatment. In addition, combination treatment showed different effects on pro-apoptotic/anti-apoptotic genes expression according to cells drug resistance properties.
Radiolabeled molecules have an important role to evaluate tumor characteristics such as aggressiveness, and to identify the
effectiveness of cancer treatments such as chemotherapy and radiotherapy. Various radionuclide (18F, 99mTc, 124I) labeled molecules can be used apoptosis detection by estimating decrescendos cell viability after therapy. 99mTc-tetrofosmin which is used as a myocardial perfusion imaging agent in routine and at the same time is known to accumulate
in various tumors including breast tumor. The aim of this study was to assess the utility of 99mTc-tetrofosmin for monitoring the early response of MCF-7 breast cancer to chemotherapy. To evaluate the role of 99mTc-tetrofosmin in vitro chemotherapy, the uptake ratio was determined using MCF-7 breast cancer line after the cells had been
treated with cisplatin. When we examined the apoptotic ratios which induced with different dose of cisplatin in MCF-7 breast
cancer cells by using Annexin V and TUNEL methods, it was observed that the rate of apoptosis increased with soaring dose.
The uptake rates of 99mTc-tetrofosmin in MCF-7 cell line in the chemotherapeutic groups were lower than it is in the control group (p < 0.01). The negative correlation between uptake ratios and apoptotic rates shows that 99mTc-tetrofosmin may be used a radiopharmaceutical for evaluating chemotherapy response. 99mTc-tetrofosmin might be probably useful as an imaging agent for estimation of early chemotherapy response in breast cancer.
The effect of 2,4,6-trimethyl-N-(meta-3-trifluoromethyl-phenyl)-benzenesulfonamide (m-3M3FBS), a presumed phospholipase C activator, on cytosolic free Ca2+ concentrations ([Ca2+]i) in OC2 human oral cancer cells is unclear. This study explored whether m-3M3FBS changed basal [Ca2+]i levels in suspended OC2 cells by using fura-2 as a Ca2+-sensitive fluorescent dye. M-3M3FBS at concentrations between 10–60 μM increased [Ca2+]i in a concentration-dependent manner. The Ca2+ signal was reduced partly by removing extracellular Ca2+. M-3M3FBS-induced Ca2+ influx was inhibited by the store-operated Ca2+ channel blockers nifedipine, econazole and SK&F96365, and by the phospholipase A2 inhibitor aristolochic acid. In Ca2+-free medium, 30 μM m-3M3FBS pretreatment inhibited the [Ca2+]i rise induced by the endoplasmic reticulum Ca2+ pump inhibitors thapsigargin and 2,5-di-tert-butylhydroquinone (BHQ). Conversely, pretreatment with thapsigargin, BHQ or cyclopiazonic acid partly reduced m-3M3FBS-induced [Ca2+]i rise. Inhibition of inositol 1,4,5-trisphosphate formation with U73122 did not alter m-3M3FBS-induced [Ca2+]i rise. At concentrations between 5 and 100 μM m-3M3FBS killed cells in a concentration-dependent manner. The cytotoxic effect of m-3M3FBS was not reversed by prechelating cytosolic Ca2+ with 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA). Propidium iodide staining data suggest that m-3M3FBS (20 or 50 μM) induced apoptosis in a Ca2+-independent manner. Collectively, in OC2 cells, m-3M3FBS induced [Ca2+]i rise by causing inositol 1,4,5-trisphosphate-independent Ca2+ release from the endoplasmic reticulum and Ca2+ influx via phospholipase A2-sensitive store-operated Ca2+ channels. M-3M3FBS also induced Ca2+-independent cell death and apoptosis.
Engi, H., Gyémánt, N., Lóránd, T. és mtsai:
Cinnamylidene ketones as potential modulators of multidrug resistance in mouse lymphoma and human colon cancercell lines. In Vivo, 2006,
An antigastric cancer monoclonal antibody, 3H11 and its Fab fragment, were labeled with #-emitter 211At using p-[211At] astatobenzoic acid (PAtBA) intermediate. The astatinated antibodies had conspicuous cytotoxic effect on human gastric cancer cell M85 in vitro. Tissue distribution of the astatinated antibodies were investigated in nude mice with subcutaneous tumor xenografts by i.v. injection. The astatinated Fab fragment was better suitable for 7.2-hour half life of 211At, since its tumor uptake remained higher (9.48–8.42 I.D%/g) than the astatinated intact antibody (~4.0 I.D%/g) from 3 to 14-hour post injection. However, the undesired high 211At uptake of the astatinated antibodies in some normal tissues, such as stomach, kidney and lung, suggested that the 211At labeled antibodies should be further explored.