Combination Chemotherapy of L1210 Tumors in Mice with Pretubulysin and Methotrexate Lipo-Oligomer Nanoparticles.

In the current study, nanoparticles containing the antimetabolite drug methotrexate (MTX) and the novel tubulin-binding drug pretubulysin (PT) were developed for combination chemotherapy. Polyelectrolyte complexes were formed based on ∼20 nm cationic nanomicelles of lipo-oligomer 454 with the anionic MTX at the molar ratio of 3:1, resulting in spherical nanoparticles with sizes of 150 nm (454 MTX). Particle formation in the presence of PT, which also interacts with 454, resulted in coloaded micelle complexes (454 PT+MTX) of 170 nm as demonstrated by transmission electron microscopy and dynamic light scattering measurements. Both drugs were incorporated to a high extent (∼85% for MTX, ∼70% for PT). Nanoparticles were stable in up to 20% serum and physiological NaCl solution. Cellular internalization of 454 PT+MTX into L1210 leukemia and KB cervix carcinoma cells was determined by confocal light scattering microscopy. The antitumor activity of the drug combination PT+MTX in both cell lines was strongly increased by drug formulation with 454 with IC50 values of PT+MTX decreasing 11-fold from 0.22 nM to 19 pM on L1210 cells and 6-fold from 2.8 to 0.48 nM on KB cervix carcinoma cells. Systemic treatment of NMRI nu/nu mice bearing subcutaneous L1210 tumors with 454 PT+MTX nanoparticles resulted in a more effective delay of tumor growth in comparison to the free drug combination of PT+MTX without 454. Importantly, nanoparticle formulation of PT+MTX with 454 increased the survival of mice by more than 100% compared to that of the buffer treated group and more than 40% compared to that of the free drug group.

Comparative Analysis of Bioactivity of the Russian-Made Antitumor Substances of the Nitrosourea Group.

We performed an in vivo comparative study of activity of three substances of the nitrosourea group produced in Russia. All substances demonstrated high antitumor activity against various solid and leukemic tumors. Aranosa significantly enhanced life duration in mice with leukemia (by 65-194%) and inhibited the growth of solid tumors (by 49-99.6%). Lisomustine and ormustine showed higher activity than aranose. Single administration of lisomustine increased life span of mice (by 22-114%) and resulted in cure of all animals in four models: lymphoblastic leukemia L-1210, lymphocytic leukemia P-388, Lewis lung carcinoma, and cervical cancer RShM-5. After ormustine treatment, full recovery was observed only in groups with lymphocytic leukemia P-388 and cervical cancer RShM-5. These findings attest to higher activity of lisomustine in the studied models.

Combined antitumoral effects of pretubulysin and methotrexate.

Pretubulysin (PT), a potent tubulin-binding antitumoral drug, and the well-established antimetabolite methotrexate (MTX) were tested separately or in combination (PT+MTX) for antitumoral activity in L1210 leukemia cells or KB cervix carcinoma cells in vitro and in vivo in NMRI-nu/nu tumor mouse models. In cultured L1210 cells, treatment with PT or MTX displays strong antitumoral effects in vitro, and the combination PT+MTX exceeds the effect of single drugs. PT also potently kills the MTX resistant KB cell line, without significant MTX combination effect. Cell cycle analysis reveals the expected arrest in G1/S by MTX and in G2/M by PT. In both cell lines, the PT+MTX combination induces a G2/M arrest which is stronger than the PT-triggered G2/M arrest. PT+MTX does not change rates of apoptotic L1210 or KB cells as compared to single drug applications. Confocal laser scanning microscopy images show the microtubule disruption and nuclear fragmentation induced by PT treatment of L1210 and KB cells. MTX changes the architecture of the F-actin skeleton. PT+MTX combines the toxic effects of both drugs. In the in vivo setting, the antitumoral activity of drugs differs from their in vitro cytotoxicity, but their combination effects are more pronounced. MTX on its own does not display significant antitumoral activity, whereas PT reduces tumor growth in both L1210 and KB in vivo models. Consistent with the cell cycle effects, MTX combined at moderate dose boosts the antitumoral effect of PT in both in vivo tumor models. Therefore, the PT+MTX combination may present a promising therapeutic approach for different types of cancer.

A new malyngamide from the marine cyanobacterium Moorea producens.

A new malyngamide (1) was isolated along with seven known compounds (2-8) from the marine cyanobacterium Moorea producens collected in Hawaii. Compound 1 represented the first reported malyngamide with a hydroxy moiety at C-7 of the characteristic fatty acid portion of the compound. Compound 1 showed cytotoxicity against L1210 cell line at an IC50 value of 2.9 mM and lethal toxicity against the shrimp Palaemon paucidens at a LD100 value of 33.3 mg/kg. The bioactivity of compound 1 was approximately 10-100 times weaker than those of isomalyngamides A and B (3, 4). These results indicated that the methoxy group at C-7 of the fatty acid section confers a degree of bioactivity in malyngamides.

Rice protein prolamin promotes anti-leukemia immunity and inhibits leukemia growth in vivo.

Prolamin is a heat-stable storage protein of rice (Oryza sativa). This study aimed to examine the effect of prolamin on anti-tumor immune response in vitro and leukemia growth in vivo. The prolamin-enriched rice fractions were prepared to stimulate peripheral blood mononuclear cells (MNC) from mice spleen. The MNC-conditioned medium (MNC-CM) was collected to treat leukemia L1210 cells. Human MNC-CM was prepared to treat Jurkat acute T cell leukemia cells. Purified prolamin was orally administered to syngeneic L1210-bearing DBA/2 mice to assess weights of tumor, liver and spleen, liver histopathology, peripheral blood neutrophil count and cytokine levels. Prolamin-prepared MNC-CM inhibited the viability of murine leukemia L1210 cells and human leukemia Jurkat cells, indicating an immunomodulatory effect. In syngeneic L1210-bearing DBA/2 mice, oral administration of purified prolamin dose-dependently decreased the tumor weight and attenuated the leukemia-induced reduction of liver and spleen weights. Prolamin inhibited the increase of peripheral blood leukocyte count. The levels of tumor necrosis factor-α and interferon-γ in MNC-CM and mice serum were significantly increased by prolamin treatment. No significant change in body weight, serum alanine aminotransferase and creatinine levels was noted by prolamin treatment. Rice prolamin could effectively promote anti-tumor immunity and inhibit leukemia growth without significant toxicity.

Compact Cell Settlers for Perfusion Cultures of Microbial (and Mammalian) Cells.

As microbial secretory expression systems have become well developed for microbial yeast cells, such as Saccharomyces cerevisiae and Pichia pastoris, it is advantageous to develop high cell density continuous perfusion cultures of microbial yeast cells to retain the live and productive yeast cells inside the perfusion bioreactor while removing the dead cells and cell debris along with the secreted product protein in the harvest stream. While the previously demonstrated inclined or lamellar settlers can be used for such perfusion bioreactors for microbial cells, the size and footprint requirements of such inefficiently scaled up devices can be quite large in comparison to the bioreactor size. Faced with this constraint, we have now developed novel, patent-pending compact cell settlers that can be used more efficiently with microbial perfusion bioreactors to achieve high cell densities and bioreactor productivities. Reproducible results from numerous month-long perfusion culture experiments using these devices attached to the 5 L perfusion bioreactor demonstrate very high cell densities due to substantial sedimentation of the larger live yeast cells which are returned to the bioreactor, while the harvest stream from the top of these cell settlers is a significantly clarified liquid, containing less than 30% and more typically less than 10% of the bioreactor cell concentration. Size of cells in the harvest is smaller than that of the cells in the bioreactor. Accumulated protein collected from the harvest and rate of protein accumulation is significantly (> 6x) higher than the protein produced in repeated fed-batch cultures over the same culture duration. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:913-922, 2017.

Involvement of mitochondrial dynamics in the antineoplastic activity of cisplatin in murine leukemia L1210 cells.

Leukemia is a type of hematopoietic stem cell malignant cloned disease with high mortality. Cisplatin-based chemotherapy is one of the most common treatments for leukemia. Similar to other chemotherapeutic agents, cisplatin resistance has become a serious issue in cancer therapy. In the present study, we investigated the role of mitochondrial dynamics in the antineoplastic activity of cisplatin in murine leukemia L1210 cells. Firstly, the L1210 cell line resistant to cisplatin (L1210/DDP) was established. Compared to its parental cell line, the IC50 value of cisplatin in the L1210/DDP cells was increased 10-fold. Mitofusins (Mfn1 and Mfn2), mitochondrial outer membrane fusion proteins, were markedly upregulated in the L1210/DDP cells, whereas the expression of fission protein Drp1 and inner membrane fusion protein OPA1 were not significantly altered. In addition, mitofusins were also upregulated in the parental L1210 cells subjected to cisplatin stress. To investigate the role of mitochondrial dynamics in the antineoplastic activity of cisplatin, the effect of mitochondrial division inhibitor (Mdivi)-1 on cisplatin­induced cell death, caspase-3 cleavage and ROS production was examined in L1210 cells. We found that 5 µM of Mdivi-1 efficiently attenuated cisplatin-induced cell death, caspase activation and intracellular ROS increase in L1210 cells. Our data indicated that mitochondrial dynamics play an important role in the antineoplastic activity of cisplatin, and mitofusin-mediated mitochondrial fusion may be involved in the process of cisplatin resistance in leukemia cells. Therefore, the present study revealed that mitochondrial dynamics may be a potential target used to improve the antineoplastic activity of cisplatin in leukemia in the future.

Preclinical Evaluation of the Short-Term Toxicity of 4-(N)-Docosahexaenoyl 2´, 2´- Difluorodeoxycytidine (DHA-dFdC).

PURPOSE: This study was designed to test the short-term toxicity of DHA-dFdC in a mouse model and its efficacy in a mouse model of leukemia at or below its repeat-dose maximum tolerated dose (RD-MTD). METHOD: A repeat-dose dose-ranging toxicity study was designed to determine the tolerability of DHA-dFdC when administered to DBA/2 mice by intravenous (i.v.) injection on a repeat-dose schedule (i.e. injections on days 0, 3, 7, 10, and 13). In order to determine the effect of a lethal dose of DHA-dFdC, mice were injected i.v. with three doses of DHA-dFdC at 100 mg/kg on days 0, 3, and 5 (i.e. a lethal-RD). The body weight of mice was recorded two or three times a week. At the end of the study, major organs (i.e. heart, liver, spleen, kidneys, lung, and pancreas) of mice that received the lethal-RD or RD-MTD were weighed, and blood samples were collected for analyses. Finally, DHA-dFdC was i.v. injected into DBA/2 mice with syngeneic L1210 mouse leukemia cells to evaluate its efficacy at or below RD-MTD. RESULTS: The RD-MTD of DHA-dFdC is 50 mg/kg. At 100 mg/kg, a lethal-RD, DHA-dFdC decreases the weights of mouse spleen and liver and significantly affected certain blood parameters (i.e. white blood cells, lymphocytes, eosinophils, and neutrophil segmented). At or below its RD-MTD, DHA-dFdC significantly prolonged the survival of L1210 leukemia-bearing mice. CONCLUSION: DHA-dFdC has dose-dependent toxicity, affecting mainly spleen at a lethal-RD. At or below its RD-MTD, DHA-dFdC is effective against leukemia in a mouse model.

Comparative studies of oxaliplatin-based platinum(iv) complexes in different in vitro and in vivo tumor models.

Using platinum(iv) prodrugs of clinically established platinum(ii) compounds is a strategy to overcome side effects and acquired resistances. We studied four oxaliplatin-derived platinum(iv) complexes with varying axial ligands in various in vitro and in vivo settings. The ability to interfere with DNA (pUC19) in the presence and absence of a reducing agent (ascorbic acid) was investigated in cell-free experiments. Cytotoxicity was compared under normoxic and hypoxic conditions in monolayer cultures and multicellular spheroids of colon carcinoma cell lines. Effects on the cell cycle were investigated by flow cytometry, and the capacity of inducing apoptosis was confirmed by flow cytometry and Western blotting. The anti-cancer activity of one complex was studied in vivo in immunodeficient and immunocompetent mice, and the platinum levels in various organs and the tumor after treatment were quantified. The results demonstrate that modification of the axial ligands can improve the cytotoxic potency. The complexes are able to interfere with plasmid DNA, which is enhanced by co-incubation with a reducing agent, and cause cell cycle perturbations. At higher concentrations, they induce apoptosis, but generate only low levels of reactive oxygen species. Two of the complexes increase the life span of leukemia (L1210) bearing mice, and one showed effects similar to oxaliplatin in a CT26 solid tumor model, despite the low platinum levels in the tumor. As in the case of oxaliplatin, activity in the latter model depends on an intact immune system. These findings show new perspectives for the development of platinum(iv) prodrugs of the anticancer agent oxaliplatin, combining bioreductive properties and immunogenic aspects.

Transmission electron microscopy method providing high resolution in the cell section without radiation damage.

Several new features of mitochondrial nucleoid and its surroundings in mammalian cells were described previously (Prachar, 2016). Very small details were observed using the improved transmission electron microscopy method, as described in the article. In the meantime, the method has again been improved to 2 Å resolutions in the cell section. The method described in detail in the present work is documented on the same records that were published in lower resolution in the work Prachar (2016), enabling comparison of the achieved resolution with the previous one. New records are also presented, showing extremely high resolution and thus implying the importance of the method. Potential use of this method in different fields is suggested.

[Platelets Decrease the Sensitivity of Leukemia Cell L1210 to Multiple Drugs via Activiting The AKT and ERK Signalling Pathway].

OBJECTIVE: To explore the effect of platelets on signal transducers and the sensitivity of leukemia cells to chemotherapeuticl drugs in leukemia cells L1210. METHODS: Murine platelets were prepared and cocultured with leukemia L1210 cells, and the aggregation between them was observed by flow cytometry. The levels of several transducer proteins in leukemia cells were analyzed with Western blot. In some experiments, methotrexate, vincristine or doxorubicin was added to the coculture system and the cell proliferation was measured by using CCK8 colorigenic methods to detect the sensitivity of leukemia cells to the therapeuticals drugs. RESULTS: Platelets, either freshly prepared or fixed with 1% paraformaldehyde, aggregated with leukemia cells. Both fresh and fixed platelets increased the level of phosphorylation of AKT and ERK in leukemia cells as measured with Western blot. Also, platelets significantly decreased the sensitivity of 3 therapeutics to L1210 cells. CONCLUSION: Platelets may bind with L1210 cells and decrease the sensitivity of the leukemia cells to chemotherapeutics, possibly by activating the AKT and ERK signaling pathways.

Fruit Extract from Pyropolyporus fomentarius (L. ex Fr.) Teng Induces Mitochondria-Dependent Apoptosis in Leukemia Cells but Enhances Immunomodulatory Activities of Splenic Lymphocytes.

Pyropolyporus fomentarius (L. ex Fr.) Teng is a unique woody mushroom due to its medicinal value with numerous pharmacological activities. This study presented the potential antitumor and immunomodulatory properties of ethanol extract of P. fomentarius. The results showed that P. fomentarius extract inhibited the viability of murine leukemia L1210 cells in a dose-dependent manner with IC50 value of 69.35 µg/ml. Flow cytometry analysis demonstrated that the extract induced apoptosis in L1210 cells. Additionally, the decline of mitochondrial membrane potential was observed as well as the changes of caspase-3, caspase-9, Bcl-2, and Bax, suggesting that proapoptosis effect of the extract involved mitochondria-related pathway. Simultaneously, the P. fomentarius extract significantly enhanced the proliferation and activation of splenic lymphocytes in a dose-dependent manner. This P. fomentarius extract has potential applications as a natural antitumor agent with immunomodulatory activity.

Effects of the combined arginase and canavanine treatment on leukemic cells in vitro and in vivo.

It was previously demonstrated in in vitro experiments that canavanine (Cav), a natural toxic arginine analogue of plant origin, is a promising candidate for augmenting the antineoplastic effects of arginine starvation. We demonstrated herein that recombinant human arginase, an arginine degrading enzyme, abrogated growth and significantly increased Cav cytotoxicity toward cultured L1210 murine leukemic cells. Cav co-treatment further reduced cells viability in a time-dependent manner and significantly promoted apoptosis induction. In the pilot study we also evaluated for the first time the potential toxicity of the combined arginine deprivation and Cav treatment in healthy mice. Administration of Cav alone or in combination with pegylated cobalt-containing human arginase (Co-hARG) did not evoke any apparent toxic effects in these animals, with no significant behavioural and survival changes after several weeks of the treatment. The therapeutic effects of the combination of Co-hARG and Cav were provisionally evaluated on the highly aggressive murine L1210 leukemia, which is semi-sensitive to arginine deprivation as a monotreatment. Combination of two drugs did not result in significant prolongation of the survival of leukemia-bearing mice. Thus, we have shown that the proposed combinational treatment is rather non-toxic for the animals. It has to be further evaluated in animal studies with alternative tumor models and/or drug doses and treatment modalities.

SYNTHESIS AND IMMUNOREGULATORY PROPERTIES OF SELECTED 5-AMINO-3-METHYL-4-ISOXAZOLECARBOXYLIC ACID BENZYLAMIDES.

The aim of the study was to characterize a series of isoxazole derivatives in several immunological tests in vitro and in vivo, in mouse and human models. The human model included measurement of: viability of peripheral blood mononuclear cells (PBMC), phytohemagglutinin A (PHA)-induced proliferation of PBMC, production of tumor necrosis factor a (TNF a) in whole blood cultures stimulated with lipopolysaccharide (LPS) and growth of SW-948 and L1210 tumor cell lines. Experiments in mice encompassed the following tests: secondary, humoral immune response splenocytes to sheep erythrocytes (SRBC) in vitiv, delayed type hypersensitivity (DTH) to ovalbumin (OVA) and carrageenan-induced foot edema. All compounds were non-toxic against PMBC and displayed differential, dose-dependent suppressive properties in the model of PHA- induced PMBC proliferation. They also exhibited differential, mostly inhibitory effects on TNF a production. The inhibitory actions on growth of tumor cell lines were moderate. M05 (5-amino-3-methyl-N-(4-methyl-benzyl)-4-isoxazolecarboxamide) was most suppressive in the proliferation and TNF a production tests, it was, therefore, selected for in vitro and in vivo studies in the mouse models. The compound inhibited the humoral immune response in vitro, stimulated the inductive phase of DTH in vivo, although it inhibited the eliciting phase of that response. The compound also inhibited the carrageenan skin reaction. M05 combines strong anti-proliferative and anti-inflammatory activities, it is therefore attractive for further studies in more advanced animal models as a potential therapeutic.

SYNTHESIS AND PHARMACOLOGICAL ACTIVITY OF IMIDAZO[2,1- b][1,3,4]THIADIAZOLE DERIVATIVES.

In this paper, a series of imidazo[2,l-b][1,3,4]thiadiazoles have been prepared by reacting 2-amino-1,3,4-thiadiazole with various phenacyl bromides in alcohol. The structures of all the derivatives were con- firmed by IR, NMR and mass spectroscopy. All the derivatives have been tested for cytostatic activity against human T-lymphocyte cells (CEM), human cervix carcinoma cells (HeLa), murine leukemia cell line (L1210), and antiviral activity. Among the tested compounds, derivatives 5b, 5c, and 7a were cytostatic between 49-63 mM against Hela and 7g was cytotoxic at 23 mM against L1210 and CEM cell lines. Compounds 5h and 7h emerged as antiviral agents with slight activity against influenza A and B.

Highly efficient uptake into cisplatin-resistant cells and the isomerization upon coordinative DNA binding of anticancer tetrazolato-bridged dinuclear platinum(II) complexes.

We examined the cytotoxicity and cellular uptake in L1210 murine leukemia cells, as well as the coordinative reaction with the guanine derivative 9-ethylguanine (9EtG), of a series of µ-hydroxo-µ-tetrazolato dinuclear platinum(II) complexes (tetrazolato-bridged complexes), [{cis-Pt(NH3)2}2(µ-OH)(µ-tetrazolato-N1,N2)](2+) (5-H-X) and [{cis-Pt(NH3)2}2(µ-OH)(µ-5-R-tetrazolato-N2,N3)](n+), where R = H (5-H-Y), CH3 (1), C6H5 (2), CH2COOCH2CH3 (3), or CH2COO(-) (4), and n = 2 (5-H-Y, 1-3) or 1 (4). Most tetrazolato-bridged complexes overcame cross-resistance to cisplatin and were more efficiently taken up into cisplatin-resistant cells (L1210R) than into parental cisplatin-sensitive cells (L1210), whereas cisplatin uptake into L1210R was decreased compared with that into L1210. The cellular uptake was most likely controlled by the total charge of the complexes. There was no correlation between the cytotoxicity and the kinetics of the coordinative reactions of 1-4 with 9EtG, but the isomerization involved in the reactions could contribute to determining the higher order structures of the compacted DNA. The cytotoxicity of tetrazolato-bridged complexes appears to correlate with the efficiency of cellular uptake and DNA compaction.

The antitumor activity of Meconopsis horridula Hook, a traditional Tibetan medical plant, in murine leukemia L1210 cells.

BACKGROUND: Meconopsis horridula Hook (M. horridula) has been used as a traditional Tibetan medicine to relieve heat and pain as well as mobilize static blood, and it is recognized as a good treatment for bruises. This study is the first trial to evaluate the tumor inhibitory activity of M. horridula extract and its underlying mechanism in the hope of providing evidence to support the anticancer function of M. horridula. METHODS AND RESULTS: M. horridula extract was cytotoxic to L1210 cells in a dose- and time-dependent manner. SEM (scanning electron microscope) observation revealed obvious morphological changes in L1210 cells after M. horridula treatment. Flow cytometry analysis demonstrated that the extract dose-dependently induced early apoptosis. Additional apoptosis parameters, such as alterations in nuclear morphology and DNA damage, were also observed. Furthermore, M. horridula treatment induced G2/M arrest. M. horridula treatment significantly increased reactive oxygen species (ROS) production, suggesting that ROS are a key factor in M. horridula-induced apoptosis. Volatile constituent detection found 15 abundant chemicals in M. horridula, which may contribute to its anticancer effect. CONCLUSION: In conclusion, M. horridula extract induced L1210 cell apoptosis and inhibited proliferation through G2/M phase arrest, and ROS were involved in the process.

[Design, synthesis, antibacterial and anti-cell proliferation activities of [1,2,4]triazino[3,4-h] [1,8]naphthyridine-8-one-7-carboxylic acid derivatives].

To discover novel fluoroquinolone lead compounds as possible anti-infective or/and antitumor chemotherapies, combination principle of pharmacophore-based drug design, a series of novel tricyclic fluoroquinolone title compounds, [1,2,4]triazino[3,4-h][1,8]naphthyridine-8-one-7-carboxylic acid derivatives ( 5a-5p), were designed and synthesized with a fused [1,2,4]-triazine ring unit. Their structures were characterized by spectral data and elemental analysis and the in vitro antibacterial and anti-cell proliferation activities were also evaluated. The results showed that the titled compounds exhibited more significant inhibitory activities against drug-resistant bacteria (Methicillin-resistant Staphylococcus aureus and multi drug-resistant Escherichia coli strains) and three tested cancer cell lines (human hepatoma SMMC-7721, murine leukemia L1210 and human murine leukemia HL60 cells). Interestingly, SAR showed that compounds with electron-donating groups attached to benzene ring had stronger antibacterial activity than antitumor activity, but electron-withdrawing compounds displayed more potential antitumor activity than antibacterial activity, especially antitumor activity of nitro compounds was comparable to comparison doxorubicin. Thus, novel triazine-fused tricyclic fluoroquinolones as potent anti-infective or/and antitumor lead compounds are valuable to pay attention and for further development.

Preferential enlargement of leukemia cells using cytoskeletal-directed agents and cell cycle growth control parameters to induce sensitivity to low frequency ultrasound.

Sonodynamic therapy (SDT) is a form of ultrasound therapy that has been shown to preferentially damage malignant cells based on the relatively enlarged size and altered cytology of neoplastic cells in comparison to normal cells. This study sought to determine whether cytoskeletal-directed agents that either disrupt (cytochalasin B and vincristine) or rigidify (jasplakinolide and paclitaxel) microfilaments and microtubules, respectively, affect ultrasonic sensitivity. U937 human monocytic leukemia cell populations were treated with each cytoskeletal-directed agent alone, and then sonicated at 23.5 kHz under relatively low power and intensity (20-40 W; 10-20 W/cm(2)), or at 20 kHz using moderate power and intensity (60 W; 80 W/cm(2)). In addition, human leukemia lines U937, THP1, K562, and Molt-4, and the murine leukemia line L1210 were sonicated using pulsed 20 kHz ultrasound (80.6 W; 107.5 W/cm(2)) both with and without the addition of cytoskeletal-directed agents to assess whether cytoskeletal-directed agents can potentiate ultrasonic sensitivity in different leukemia lines. Human hematopoietic stem cells (hHSCs) and leukocytes were sonicated with continuous 23.5 kHz ultrasound (20 W; 10 W/cm(2)) to determine whether this approach elicited the preferential damage of neoplastic cells over normal blood components. To determine whether ultrasonic sensitivity is exclusively dependent on cell size, leukemia cells were also enlarged via alteration of cell growth parameters including serum deprivation and re-addition, and plateau-phase subculturing. Results indicated that cytochalasin B/ultrasound treatments had the highest rates of initial U937 cell damage. The cells enlarged and partially synchronized, either by serum deprivation and re-addition or by plateau-phase subculturing and synchronous release, were not comparably sensitive to ultrasonic destruction based solely on their cell size. In addition, cytochalasin B significantly potentiated the ultrasonic sensitivity of all neoplastic cell lines, but not in normal blood cells, suggesting that preferential damage is attainable with this treatment protocol. Therefore, it is likely that ultrasonic cell lysis depends not only on cell size and type, but also on the specific molecular mechanisms used to induce cell enlargement and their effects on cell integrity. This is supported by the fact that either the microfilament-or microtubule-disrupting agent produced a higher rate of lysis for cells of a given size than the corresponding stabilizing agents.

N-Farnesyloxy-norcantharimide and N-farnesyl-norcantharimide inhibit the progression of leukemia and increase survival days in a syngeneic mouse leukemia model.

This study investigated the anticancer effects of two newly synthesized norcantharidin analogs, N-farnesyloxy-norcantharimide (NOC15) and N-farnesyl-norcantharimide (NC15), in L1210 cells and in a syngeneic mouse leukemia model (L1210 cell line plus DBA/2 mice). We found that the half-maximal inhibitory concentration (IC50) of NOC15 and NC15 on L1210 cells is 1.56 and 2.62 µmol/l, respectively, and that the IC50 of NOC15 and NC15 on human normal lymphoblast is 207.9 and 2569 µmol/l, respectively. In cell cycle analysis, NOC15 could increase the sub-G1 phase, whereas NC15 could induce G2/M arrest. Annexin-V apoptosis assay indicated that both NOC15 and NC15 could induce cell apoptosis. In the syngeneic mouse leukemia model, both NOC15 and NC15 could increase the survival days of mice and decrease the tumor weight. Moreover, both NOC15 and NC15 could retard the increase in peripheral blood leukocyte count due to L1210 cells. In the subcutaneous (s.c.) group, the treatment with NOC15 could retard the decrease in the weight of the liver and the spleen caused by L1210 cells, whereas the treatment with NC15 could retard the decrease in the weight of the spleen caused by L1210 cells. We conclude that the new compounds NOC15 and NC15 have strong anticancer activity and low toxicity both in vitro and in vivo. NOC15 and NC15 may have the potential to be developed into anticancer agents in the future.