A Review on Patient-Derived 3D Micro Cancer Approach for Drug Screen in Personalized Cancer Medicine.

Precision medicine in oncology aims to identify an individualized treatment plan based on genomic alterations in a patient's tumor. It helps to select the most beneficial therapy for an individual patient. As it is now known that no patient's cancer is the same, and therefore, different patients may respond differently to conventional treatments, precision medicine, which replaces the one-size-fits-all approach, supports the development of tailored treatments for specific cancers of different patients. Patient-specific organoid or spheroid models as 3D cell culture models are very promising for predicting resistance to anti-cancer drugs and for identifying the most effective cancer therapy for high-throughput drug screening combined with genomic analysis in personalized medicine. Because tumor spheroids incorporate many features of solid tumors and reflect resistance to drugs and radiation, as in human cancers, they are widely used in drug screening studies. Testing patient-derived 3D cancer spheroids with some anticancer drugs based on information from molecular profiling can reveal the sensitivity of tumor cells to drugs and provide the right compounds to be effective against resistant cells. Given that many patients do not respond to standard treatments, patient-specific treatments will be more effective, less toxic. They will affect survival better compared to the standard approach used for all patients.

Cerium oxide nanoparticles exert antitumor effects and enhance paclitaxel toxicity and activity against breast cancer cells.

Cerium oxide nanoparticles (CeONPs) displayed cytotoxic properties against some cancer cells. However, there is very limited data about the possible antitumoral potential of them in breast cancer cells when used alone and/or together with a chemotherapeutic drug. We investigated the effects of CeONPs alone or in combination with paclitaxel (PAC) on healthy or carcinoma breast cells. After human breast cancer cells (MCF-7) treated with CeONPs alone or together with PAC for 24, 48, and 72 h, the effects of CeONPs on cell viability, apoptosis, migration, and adhesion were investigated. All cell viability and IC50 values of CeONPs and PAC treatments in healthy breast cells (HTERT-HME1) were higher than MCF-7 cells. They showed higher cytotoxicity against MCF-7 cells. CeONPs (10, 20, and 30 mM) and/or abraxane (AB) (2 µM) significantly decreased cell viability values in MCF-7 cells. All CeONPs concentrations increased the number of apoptotic MCF-7 cells. CeONPs (20 and 30 mM) alone or in combination with AB for 72 h treatment also significantly increased the apoptosis in compared to AB alone. CeONPs and/or AB can significantly inhibit the migratory ability of breast cancer cells. The migration rates in co-treated groups with CeONPs and AB were lower than CeONPs treatments. Higher concentrations of CeONPs alone or together with AB inhibited cell adhesion. Our results showed CeONPs can increase cytotoxicity and apoptosis and decrease cell migration and cell adhesion when used alone or together with AB. Therefore, combination of chemotherapeutics with CeONPs may provide a good strategy against cancer.

Whey protein protects liver mitochondrial function against oxidative stress in rats exposed to acrolein.

Acrolein (AC) is one of the most toxic environmental pollutants, often associated with incomplete combustion of petrol, wood, and plastic, oil frying, and tobacco smoking, that causes oxidative damage to DNA and mitochondria. Considering that little is known about the protective effects of whey protein (WP) against AC-induced liver toxicity, the aim of our study was to learn more about them in respect to liver mitochondrial oxidative stress, respiratory enzymes, Krebs cycle enzymes, and adenosine triphosphate (ATP). To do that, we treated Sprague Dawley rats with daily doses of AC alone (5 mg/kg bw in 0.9 % NaCl solution), WP alone (200 mg/kg bw, in 0.9 % NaCl solution), or their combination by oral gavage for six days a week over 30 days. As expected, the AC group showed a drop in glutathione levels and antioxidant, transport chain, and tricarboxylic acid cycle enzyme activities and a significant rise in mitochondrial lipid peroxidation and protein carbonyl levels. Co-treatment with WP mitigated oxidative stress and improved enzyme activities. Judging by the measured parameters, WP reduced AC toxicity by improving bioenergetic mechanisms and eliminating oxidative stress.

Cytotoxic, genotoxic, and carcinogenic effects of acrylamide on human lung cells.

While an association between acrylamide (AC) exposure and the risk of developing cancer has been shown in some studies, there are very limited data on the relationship between AC exposure and lung cancer risk. Thus, we investigated the cytotoxic, genotoxic, and carcinogenic effects of AC on human lung bronchial epithelial cell line (BEAS-2B cells). AC (5 and 10 mM) significantly decreased the cell viability for all treatment times. The comet assay results showed that AC (0.5, 1 and 5 mM) increased the DNA tail (%), tail moment and olive tail moment. By using immunofluorescence, we found that AC (0.5, 1 and 5 mM) induced the formation of both phosphorylated form of the histone H2 variant H2AX (gH2AX) and p53-binding protein 1 (53BP1) foci. AC-treated BEAS-2B cells exhibited various morphological and cytoplasmic changes. The transformed cells can induce form foci and significantly increase the number of colonies in soft agar. We showed for the first time that AC could induce DNA strand breaks, cell transformation, and anchorage-independent growth in BEAS-2B cells. Therefore, AC exposure can induce carcinogenesis in lung cells and may be a risk for lung cancer formation. Further studies are necessary to make a possible risk assessment in humans.

Conjugated linoleic acid protects brain mitochondrial function in acrolein induced male rats.

Acrolein (AC) is a toxic substance that can have a neurotoxic effect. It can cause oxidative stress and mitochondrial dysfunction. Conjugated linoleic acid (CLA), a dietary supplement, has many biological functions. Limited information is available about the effect of CLA on AC-induced brain toxicity. Therefore, the present study aims to investigate the effect of CLA on mitochondrial oxidative stress, respiratory enzymes, krebs cycle enzymes and ATP levels in AC treated rat brain. Sprague Dawley male rats were given AC (5 mg/kg i.p.), CLA (200 mg/kg orally) and CLA with AC for six days per week for 30 days. Some oxidative stress parameters and mitochondrial enzymes such as manganese super oxide dismutase, glutathione peroxidase, NADP+-dependent isocitrate dehydrogenase (ICDH), alpha-ketoglutarate dehydrogenase (α-KGDH), malate dehydrogenase, reduced glutathione (GSH), lipid peroxidation (LP), protein carbonyl (PC), oxidative phosphorylation (OXPHOS) and tricarboxylic acid cycle (TCA) enzymes, and ATP levels were determined. AC significantly decreased the activities of GSH, antioxidant enzymes, OXPHOS enzymes (complex I and IV), TCA enzymes (ICDH and α-KGDH) and ATP levels. Significant increases were also observed in mitochondrial LP and PC levels in AC group. Co-treatment with AC + CLA improved oxidative stress and mitochondrial dysfunction caused by AC. As a result of our findings, it was observed that CLA was effective in improving oxidative stress and impaired mitochondrial functions in brain tissue by the effect of AC. Considering the association between neurodegenerative diseases and mitochondrial dysfunction, CLA can play a role in the prevention and therapy of neurodegenerative disorders.

Trimetazidine alone or in combination with gemcitabine and/or abraxane decreased cell viability, migration and ATP levels and induced apoptosis of human pancreatic cells.

BACKGROUND: Trimetazidine (TMZ) is an anti-ischemic agent that can inhibit the fatty acid oxidation. It has been stated that inhibition of fatty acid oxidation may be an acceptable approach to cancer treatment. METHODS: We examined the effects of TMZ alone or together with abraxane (ABX) and/or gemcitabine (GEM) on cell viability, apoptosis, adhesion, migration and ATP levels of human pancreatic cancer cell line PANC-1. RESULTS: TMZ significantly reduced the cell viability at higher concentrations. Lower cell viability values were found in cells co-treated with TMZ + GEM, TMZ + ABX and GEM + ABX. The combined treatment of TMZ with ABX and/or GEM significantly increased the apoptosis rates. The highest percentages of apoptosis were found in TMZ + ABX or TMZ + ABX + GEM treatments. TMZ alone or together with ABX and/or GEM significantly reduced the ATP levels. The lowest migration rates were also found at TMZ + ABX and TMZ + ABX + GEM treatments. CONCLUSIONS: Our study is the first study to indicate that TMZ can induce cytotoxicity and apoptosis and reduce migration and ATP levels, especially in cells co-treated with ABX and/or GEM. A combination strategy based on inhibition of fatty acid oxidation and anticancer drugs may be more effective in the treatment of pancreatic cancers.

Increased DNA strand breaks and neoplastic transformation in human bladder cells treated with pioglitazone.

Pioglitazone (PIO), an oral hypoglycemic agent, is used in the treatment of type 2 diabetes. Some studies have suggested that an increased risk of bladder cancer with PIO exposure, while the others reported there is no such relationship. Therefore, it is doubtful whether PIO can increase the risk of bladder cancer. The effects of PIO on DNA damage and/or transformation of human bladder cells are not fully known. We investigated the effects of PIO on cytotoxicity, DNA single and double strand breaks and repair and neoplastic transformation in human bladder cells (hTU1) treated with 10, 20, and 40 µM PIO for 24, 48 and 72 hr. PIO decreased cell viability in a concentration-dependent manner. Increased levels of comet parameters showed that PIO and its metabolites can significantly induce DNA double strand breaks at all concentrations tested. PIO also significantly induced the formation of phosphorylated H2AX and p53 binding protein 1 foci. DNA damage was not repaired in a 24 hr recovery period. PIO can also induce malignant transformation of human bladder cells exhibiting loss of contact inhibition and anchorage independent growth. This is the first study to indicate that PIO can induce DNA damage and malignant transformation, reduce or alter the DNA repair capacity in human bladder cells. From these results, we suggest that patients with diabetes treated with PIO may have an increased risk of bladder cancer.

In vitro cytogenetic activity of 3-amino-4-[4-(dimethylamino)phenyl]-4,5-dihydro-1,2,5-thiadiazole 1,1-dioxide.

In a previous study, 3-amino-4-[4-(dimethylamino)phenyl]-4,5-dihydro-1,2,5-thiadiazole 1,1-dioxide (DPTD), which is five-membered cyclosulfamide, was synthesized and structurally characterized. The aim of this study was to investigate the cytotoxic and genotoxic effects of DPTD on cultured human lymphocytes in the presence and absence of a metabolic activation system (S9 mix). The cytotoxicity and genotoxicity of DPTD in human peripheral blood lymphocytes were examined in vitro by using chromosomal aberration (CA) and micronucleus (MN) tests. Mitomycin-C (MMC) for cultures without S9 mix and cyclophosphamide monohydrate (CP) for cultures with S9 mix were used as positive controls. The cultures were treated with DPTD (45, 90, and 180 µg/mL) in the absence and presence of S9 mix. The cells were also co-treated with DPTD together with MMC or CP. DPTD showed cytotoxic activity due to decreases in mitotic index (MI) and nuclear division index (NDI) in the absence and presence of S9 mix. DPTD also increased the CAs, aberrant cells with CAs and MN values in cultures with and without S9 mix. When DPTD and MMC or CP were used together, lower MI and NDI values and higher CA and MN values were found than those DPTD treated alone. Both DPTD and its metabolites have cytotoxic, cytostatic and genotoxic potential on human peripheral blood lymphocyte cultures under the experimental conditions. Furthermore, co-treatment of DPTD and MMC or CP can cause more cytotoxicity and genotoxicity. Our results indicated that the use of DPTD with other chemotherapeutic drugs may display more effective results.

Effects of deltamethrin and thiacloprid on cell viability, colony formation and DNA double-strand breaks in human bronchial epithelial cells.

Deltamethrin (DEL) and thiacloprid (THIA) are commonly used insecticides applied either separately or as a mixture. We aimed to investigate the effects of DEL and THIA on cell viability, proliferation and DNA damage in human bronchial epithelial cells (BEAS-2B) because their effects in lung cells are not known. Our results indicate that all concentrations of DEL and THIA statistically decreased colony formation, plating efficiency and survival fraction in a concentration-dependent manner in BEAS-2B cells expect the lowest concentration for 24 h. MTT assay showed that treatment of DEL + THIA increased the cytotoxicity at higher concentrations. DEL + THIA significantly induced the foci formation of phosphorylated H2AX protein and p53 binding protein 1 at the highest concentration (44 µM DEL+666 µM THIA) for 120 h. Because gH2AX foci number was still higher in the recovery group given an additional 24 h after 120 h, the recovery period was not sufficient for DNA double-strand breaks repair.

Protective effect of Argan oil on mitochondrial function and oxidative stress against acrylamide-induced liver and kidney injury in rats.

CONTEXT: Acrylamide (ACR) is now a risk for general public health. Argan oil (AO) is harvested from the fruits of Argania spinosa and its rich source of antioxidant and phenolic compounds. OBJECTIVE: The aim of present study was to investigate the protective effect of AO against ACR-induced liver and kidney injury in rats. MATERIALS AND METHODS: Rats were exposed to ACR (50 mg/kg/day three times per week), AO (6 ml/kg/day per day) and ACR together with AO for 30 days. Oxidative status and mitochondrial functions were evaluated in liver and kidney. RESULTS: Although ALT, AST, urea and creatine levels in serum, myeloperoxidase and total nitrite (NOx) levels in the tissues, lipid peroxidation and protein carbonyls levels were increased in the ACR-treated rats, cytosolic glucose-6-phosphate dehydrogenase and glutathione-S-transferase activities, mitochondrial antioxidant enzyme activities, glutathione levels, oxidative phosphorylation enzymes, TCA cycle enzymes, mitochondrial metabolic function and ATP level were decreased. The administration of ACR together with AO normalised almost all these parameters. CONCLUSION: Over recent years, compounds that specifically target mitochondria have emerged as promising therapeutic options for patients with hepatic and renal diseases. We think that AO oil is one of these compounds due to its unique content.

Clothianidin induces DNA damage and oxidative stress in bronchial epithelial cells.

Clothianidin (CHN) is a member of the neonicotinoid group of insecticides. Its oxidative and DNA damage potential for human lung cells are not known. Therefore, the present study was designed to examine the effects of CHN on DNA damage and oxidative stress in human bronchial epithelial cells (BEAS-2B) treated with CHN for 24, 72, and 120 hr. Our results indicate that CHN decreased cell viability in a concentration-dependent manner. CHN induced DNA single-strand breaks because alkaline comet parameters such as tail intensity, DNA in the tail, tail moment, and tail length increased. All CHN concentrations also significantly induced the formation of DNA double-strand breaks (DSBs) because it increased phosphorylated H2AX protein foci for all treatment times and p53-binding protein 1 foci for all treatments except for the lowest concentration (0.15 mM) of 120-hr treatment. DNA damage caused by DNA DSBs was not repaired in a 24-hr recovery period. CHN also induced oxidative stress by decreasing reduced glutathione and increasing lipid peroxidation. These results make it necessary to conduct studies about the detailed carcinogenic potential of CHN in humans because it can induce both oxidative and DNA damage.

In vitro cytogenetic assessment and comparison of vildagliptin and sitagliptin.

Vildagliptin and sitagliptin are commonly used antidiabetic drugs. Chromosomal aberration (CA), sister chromatid exchange (SCE) and cytokinesis-block micronucleus (CBMN) assays were employed to assess and compare cytotoxic and genotoxic effects of these drugs. Peripheral lymphocytes were exposed to 125 µg/ml, 250 µg/ml and 500 µg/ml of vildagliptin and 250 µg/ml, 500 µg/ml and 1000 µg/ml of sitagliptin for 24 h and 48 h with and without exogenous metabolic activation. At the end of the study, it was determined that these drugs and their metabolites had no genotoxic effects on CA, SCE and CBMN. On the other hand, parallel to the increase in dose, vildagliptin showed weak cytotoxicity on the mitotic index, and depending on its increase in dose; sitagliptin caused potential cytotoxicity and cytostatic effect on the mitotic index, nuclear division index and proliferation index. Due to their cytotoxic and cytostatic potential, these drugs inhibit cell proliferation.

Cytotoxicity and genotoxicity of clothianidin in human lymphocytes with or without metabolic activation system.

Clothianidin (CHN) is a broad-spectrum neonicotinoid insecticide. Limited studies have been carried out on the cytotoxic and genotoxic effects of both CHN using different genotoxicity tests in human cells with or without human metabolic activation system (S9 mix). Therefore, the aim of this study is to investigate the cytotoxic and genotoxic effects of CHN and its metabolites on human lymphocyte cultures with or without S9 mix using chromosomal aberration (CA) and micronucleus (MN) tests. The cultures were treated with 25, 50, and 100 µg/ml of CHN in the presence (3 h treatment) and absence (48 h treatment) of S9 mix. Dimethyl sulfoxide (DMSO) was used as a solvent control. CHN showed cytotoxic and genotoxic effects due to significant decreases in mitotic index (MI) and nuclear division index (NDI), and significant increases in the CAs, aberrant cells, and MN formation in the absence of S9 mix when compared with solvent control. However, CHN did not significantly induce cytotoxicity and genotoxicity in the presence of S9 mix. Our results indicated that CHN has cytotoxic, cytostatic, and genotoxic potential on human peripheral blood lymphocyte cultures, but not its metabolites under the experimental conditions.

Effects of whey protein and conjugated linoleic acid on acrolein-induced cardiac oxidative stress, mitochondrial dysfunction and dyslipidemia in rats.

Acrolein is a ubiquitous environmental pollutant. Whey protein and conjugated linoleic acid are widely used weight-loss supplements. We aimed to evaluate blood lipid profiles, oxidative stress and mitochondrial bioenergetics function in hearts of rats treated with acrolein and/or the weight-loss supplements. The animals were orally gavaged with acrolein, whey protein, conjugated linoleic acid, acrolein + whey protein or acrolein + conjugated linoleic acid for six days per week during 30 days. Acrolein caused dyslipidemia and oxidative stress in red blood cells and haert mitochondria. Moreover, it caused dysfunction in mitochondrial bioenergetics by decreasing levels of oxidative phosphorylation enzymes, tricarboxylic acid cycle enzymes and ATP. Co-treatment with acrolein + whey protein and acrolein + conjugated linoleic acid ameliorated acrolein-induced oxidative stress and dysfunction in mitochondrial bioenergetics. This amelioration effect was more prominent in acrolein + conjugated linoleic acid group. Interestingly, co-treatment with acrolein + whey protein negatively affected some markers of cardiac injury such as creatinine kinase-MB, lactate dehydrogenase and homocysteine. Conjugated linoleic acid may also cause dyslipidemia because it increased the levels of triacylglycerol, low density lipoproteins and very low density lipoproteins. In conclusion, using some weight loss supplements such as whey protein may adversely affect the biochemical parameters related to cardiovascular system.

Hepatoprotective effects of capsaicin and alpha-tocopherol on mitochondrial function in mice fed a high-fat diet.

Capsaicin (CAP) and alpha-tocopherol (TOC) have antioxidant properties. We investigated effects of CAP and TOC on mitochondrial oxidative stress and mitochondrial bioenergetics in liver of mice fed HFD. AST, ALT, glucose, homeostasis model assessment-insulin resistance index ((HOMA-IR)) and mitochondrial oxidative stress parameters increased, whereas oxidative phosphorylation (OXPHOS) enzymes, tricarboxylic acid cycle (TCA) enzymes, ATP level and mitochondrial metabolic function (MTT) decreased in mice fed a HFD compared to the fed a standard diet (NC). Treatment of HFD together with CAP (HFC group), TOC (HFT group) or TOC and CAP (HCT group) can ameliorate the examined parameters. Because co-treatment with CAP and TOC displayed a better ameliorating effect on liver redox status and mitochondrial bioenergetics functions, they can be useful to protect against HFD and oxidative stress-related in liver diseases.

Acrolein-induced oxidative stress and genotoxicity in rats: protective effects of whey protein and conjugated linoleic acid.

Acrolein (AC), a highly reactive hazardous pollutant, poses serious threats to human health. Whey protein (WP) and conjugated linoleic acid (CLA) have beneficial health implications. We investigated the protective effects of WP and CLA against AC-induced toxicity in rats. The animals were orally gavaged with CLA (200 mg/kg/day), WP (200 mg/kg/day), AC (5 mg/kg/day), CLA + AC (200 + 5 mg/kg/day), and WP + AC (200 + 5 mg/kg/day) six days per week for 30 days. The oral administration of AC significantly induced oxidative stress by increasing thiobarbituric acid reactive substances (TBARS) and protein carbonyls (PCOs) levels and decreasing glutathione (GSH) level in the spleen, thymus, and polymorphonuclear leukocytes (PMNs). It also increased the frequencies of micronucleus (MN) and megakaryocytic emperipolesis (ME) and decreased the ratio of polychromatic erythrocytes (PCEs) in bone marrow. Slight alterations in urinary 8-hydroxydeoxyguanosine (8-OHdG) levels were not significant. Co-treatment with CLA + AC or WP + AC ameliorated the values of oxidative stress, MN, PCE, and ME. These data suggest that CLA and WP can improve the antioxidant defenses and preclude the formation of genetic damage and ME.

Effects of tartrazine on proliferation and genetic damage in human lymphocytes.

The color additive, tartrazine (TRZ), is widely used in food products, drugs and cosmetics. Genotoxicity of TRZ and its metabolites has not been investigated in detail in the presence and absence of a metabolic activator (S9 mix) in human. Therefore, the aim of this study is to investigate the cytotoxic and genotoxic effects of TRZ and its metabolites on cultured human lymphocytes by using chromosome aberration (CA) and micronucleus (MN) tests. Cultures were treated with 625, 1250 and 2500 µg/ml of TRZ in the presence and absence of S9 mix. TRZ showed cytotoxic activity at the highest concentration due to significant decrease in mitotic index (MI) in the absence of S9 mix when compared with solvent control. TRZ and metabolites significantly increased the CAs and aberrant cells in the presence and absence of S9 mix at the higher concentrations. Increased MN values in cultures with and without S9 mix were found to significantly at the highest concentration when tested. Our results indicated that while both TRZ and its metabolites have genotoxic potential on human lymphocyte cultures with and without S9 mix, TRZ can induce cytotoxicity at the highest concentration in culture without S9 mix under the experimental conditions.

Cytogenetic alterations in human lymphocyte cultures following exposure to ofloxacin.

Ofloxacin (OFX), a second-generation of quinolones, is a broad-spectrum flouroquinolone antibiotic used in the treatment of various bacterial infections. In this article, we aimed to investigate the cytotoxic and genotoxic potentials of OFX in cultured human peripheral lymphocytes. The cytotoxicity and genotoxicity of OFX on human peripheral blood lymphocytes were examined in vitro by sister chromatid exchange (SCE), chromosomal aberrations (CAs) and micronucleus (MN) tests. Cultures were treated with 30, 60 and 120 µg/ml of OFX for 48 h. Dimethylsulfoxide (DMSO) was used as a solvent control. OFX decreased the mitotic index (MI) and nuclear division index (NDI) significantly, especially at higher concentrations (60 and 120 µg/ml) compared with solvent control. OFX significantly induced CAs at all concentrations and SCEs at higher concentrations (60 and 120 µg/ml) compared with solvent control. In conclusion, our results indicated that OFX has cytotoxic, cytostatic and genotoxic potential especially at higher concentrations on human peripheral blood lymphocyte cultures under the experimental conditions.

Ziprasidone induces cytotoxicity and genotoxicity in human peripheral lymphocytes.

It has been stated that some antipsychotic drugs might cause genotoxic and carcinogenic effects. Ziprasidone (ZIP) is commonly used an antipsychotic drug. However, its genotoxicity and carcinogenicity data are very limited. The cytotoxicity and genotoxicity of ZIP on human peripheral blood lymphocytes were examined in vitro by sister chromatid exchange (SCE), chromosome aberration (CA) and micronucleus (MN) tests in this study. Lymphocyte cultures were treated with 50, 75 and 100 µg/ml of ZIP in the presence and absence of a metabolic activator (S9 mix). Dimethylsulfoxide was used as a solvent control. While the cells were treated with ZIP for 24 h and 48 h in cultures without S9 mix, the cultures with S9 mix were exposed to ZIP for 3 h. ZIP and its metabolites can exert cytotoxic activities due to significant decreases in mitotic index, proliferation index and nuclear division index in the presence and absence of S9 mix. Statistically significant increases in CAs, aberrant cells and MN values in the presence and absence of S9 mix were found in cultures treated with ZIP. While ZIP significantly increased the SCE values in the absence of S9 mix at all concentrations, increased SCE values in cultures with S9 mix were not found to significantly at all concentrations tested. Our results indicated that both ZIP and its metabolites have cytotoxic, cytostatic and genotoxic potential on lymphocyte cultures under the experimental conditions. Further studies are necessary to make a possible risk assessment in patients receiving therapy with this drug.

Oxcarbazepine-induced cytotoxicity and genotoxicity in human lymphocyte cultures with or without metabolic activation.

There has been considerable debate about the relationship between epilepsy and cancer. Oxcarbazepine (OXC) is used for treating certain types of seizures in patients with epilepsy. There have been no detailed investigations about genotoxicity of OXC and its metabolites. Therefore, the aim of this study is to investigate the cytotoxic and genotoxic effects of OXC and its metabolites on cultured human lymphocytes. The cytotoxicity and genotoxicity of OXC on human peripheral blood lymphocytes were examined in vitro by sister chromatid exchange (SCE), chromosomal aberration (CA) and micronucleus (MN) tests. Cultures were treated with 125, 250 and 500 µg/ml of OXC in the presence (3 h treatment) and absence (24 h and 48 h treatment) of a metabolic activator (S9 mix). Dimethyl sulfoxide (DMSO) was used as a solvent control. OXC showed cytotoxic activities due to significant decreases in mitotic index (MI), proliferation index (PI) and nuclear division index (NDI) in the absence of S9 mix when compared with solvent control. Metabolites of OXC also significantly reduced MI and PI in cultures with S9 mix. OXC significantly increased the CAs, aberrant cells, SCE and MN values in the presence and absence of S9 mix. Our results indicated that both OXC and its metabolites have cytotoxic, cytostatic and genotoxic potential on human peripheral blood lymphocyte cultures under the experimental conditions. Further studies are necessary to elucidate the relationship between cytotoxic, cytostatic and genotoxic effects, and to make a possible risk assessment in patients receiving therapy with this drug.