In vitro investigating of anticancer activity of new 7-MEOTA-tacrine heterodimers

A combination of biochemical, biophysical and biological techniques was used to study calf thymus DNA interaction with newly synthesized 7-MEOTA-tacrine thiourea 12-17 and urea heterodimers 18-22, and to measure interference with type I and II topoisomerases. Their biological profile was also inspected in vitro on the HL-60 cell line using different flow cytometric techniques (cell cycle distribution, detection of mitochondrial membrane potential dissipation, and analysis of metabolic activity/viability). The compounds exhibited a profound inhibitory effect on topoisomerase activity (e.g. compound 22 inhibited type I topoisomerase at 1 µM concentration). The treatment of HL-60 cells with the studied compounds showed inhibition of cell growth especially with hybrids containing thiourea (14-17) and urea moieties (21 and 22). Moreover, treatment of human dermal fibroblasts with the studied compounds did not indicate significant cytotoxicity. The observed results suggest beneficial selectivity of the heterodimers as potential drugs to target cancer cells.

Novel trisubstituted acridines as human telomeric quadruplex binding ligands

A novel series of trisubstituted acridines were synthesized with the aim of mimicking the effects of BRACO19. These compounds were synthesized by modifying the molecular structure of BRACO19 at positions 3 and 6 with heteroacyclic moieties. All of the derivatives presented in the study exhibited stabilizing effects on the human telomeric DNA quadruplex. UV-vis spectroscopy, circular dichroism, linear dichroism and viscosimetry were used in order to study the nature of the DNA binding in more detail. The results show that all of the novel derivatives were able to fold the single-stranded DNA sequences into antiparallel G-quadruplex structures, with derivative 15 exhibiting the highest stabilizing capability. Cell cycle analysis revealed that a primary trend of the "braco"-like derivatives was to arrest the cells in the S- and G2M-phases of the cell cycle within the first 72h, with derivative 13 and BRACO19 proving particularly effective in suppressing cell proliferation. All studies derivatives were less toxic to human fibroblast cell line in comparison with HT 29 cancer cell line.

Interaction of cholinesterase modulators with DNA and their cytotoxic activity

This research was focused on a study of the binding properties of a series of cholinesterase reactivators compounds K075 (1), K027 (2) and inhibitors compounds K524, K009 and 7-MEOTA (3-5) with calf thymus DNA. The nature of the interactions between compounds 1-5 and DNA were studied using spectroscopic techniques (UV-vis, fluorescence spectroscopy and circular dichroism). The binding constants for complexes of cholinesterase modulators with DNA were determined from UV-vis spectroscopic titrations (K=0.5 × 10(4)-8.9 × 10(5)M(-1)). The ability of the prepared analogues to relax topoisomerase I was studied with electrophoretic techniques and it was proved that ligands 4 and 5 inhibited this enzyme at a concentration of 30 μM. The biological activity of the novel compounds was assessed through an examination of changes in cell cycle distribution, mitochondrial membrane potential and cellular viability. Inhibitors 3-5 exhibited a cytotoxic effect on HL-60 (human acute promyelocytic leukaemia) cell culture, demonstrated a tendency to affect mitochondrial physiology and viability, and also forced cells to accumulate in the G1/G0-phase of the cell cycle. The cholinesterase reactivators 1 and 2 were found relatively save from the point of view of DNA binding, whereas cholinesterase inhibitors 3-5 resulted as strong DNA binding agents that limit their plausible use.

Degradation of HER2 receptor through hypericin-mediated photodynamic therapy

Current treatment of breast cancer is often affected by resistance to therapeutics, for which the human epidermal growth factor receptor 2 (HER2) may be responsible. Here, we report for the first time the use of hypericin-mediated photodynamic therapy (HY-PDT) in combination with a selective HER2 inhibitor (AG 825) on SKBR-3, a HER2 overexpressing human breast adenocarcinoma cell line. The results demonstrate that HY-PDT is able to degrade HER2 with an impact on its signaling cascade. Combination with AG 825 resulted in increased apoptosis induction, total degradation of HER2 and inhibition of colony formation. Downregulation of HSP90, Mcl-1, Bcl-xL and upregulation of Bax was also observed. This knowledge provides the basis for the possible application of HY-PDT in preclinical and clinical models of breast cancer treatment.

Down-regulation of Bcl-2 and Akt induced by combination of photoactivated hypericin and genistein in human breast cancer cells

Presented experiment considers combination of genistein and photodynamic therapy with hypericin with a view to achieve higher therapeutic outcome in human breast adenocarcinoma cell lines MCF-7 and MDA-MB-231, both identified in our conditions as photodynamic therapy resistant. Since genistein is known to suppress Bcl-2 expression, we predicted that photodynamic therapy with hypericin might benefit from mutual therapeutic combination. In line with our expectations, combined treatment led to down-regulation of Bcl-2 and up-regulation of Bax in both cell lines as well as to suppression of Akt and Erk1/2 phosphorylation induced by photoactivated hypericin in MCF-7 cells. Although Akt and Erk1/2 phosphorylation was not stimulated by photodynamic therapy with hypericin in MDA-MB-231 cells, it was effectively suppressed in combination. Variations in cell death signaling favoring apoptosis were indeed accompanied by cell cycle arrest in G(2)/M-phase, activation of caspase-7, PARP cleavage and increased occurrence of cells with apoptotic morphology of nucleus. All these events corresponded with suppression of proliferation and significantly lowered clonogenic ability of treated cells. In conclusion, our results indicate that pre-treatment with tyrosine kinase inhibitor genistein may significantly improve the effectiveness of photodynamic therapy with hypericin in MCF-7 and MDA-MB-231 breast cancer cells.

Drug efflux transporters, MRP1 and BCRP, affect the outcome of hypericin-mediated photodynamic therapy in HT-29 adenocarcinoma cells

Photodynamic therapy (PDT) is a flexible multi-target therapeutic approach. One of the main requirements of successful PDT is sufficient intracellular concentration of an applicable photosensitizer. Mechanisms of anticancer drug elimination by tumour cells are mostly linked to the elevated expression and activity of P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1), breast cancer resistance protein (BCRP) and P450 monooxygenases. The interaction of hypericin with this cell drug-defence system is still unclear. We report here for the first time increased activity of MRP1 and BCRP in HT-29 colon cancer cells treated with hypericin per se. On the contrary, pre-treatment with proadifen (SKF525A) affected the function of MRP1 and BCRP leading to increased hypericin content, which might indicate a possible link between proadifen and these ABC transporter proteins. Subsequent enhanced intracellular oxidative stress was accompanied by loss of mitochondrial membrane potential, activation of caspase-9 and -3, PARP cleavage and onset of apoptosis. In conclusion, our study suggests that drug efflux transporters MRP1 and BCRP affect the pharmacokinetics of hypericin in HT-29 colon adenocarcinoma cells, and the action of hypericin-mediated PDT (HY-PDT) should be modulated by pre-treatment with their specific inhibitors.

Radioprotection of Mice by the Bacterial Extract Broncho-VaxomR: Haemopoietic Stem Cells and Survival Enhancement

Pretreatment of mice with 50-1000 micrograms of the bacterial extract Broncho-Vaxom (BV, free of endotoxin) before sublethal irradiation induced an increase in the number of endogenous haemopoietic stem cells (E-CFU). The degree of radioprotection was dependent on both the time of administration and the dose of BV. An optimal E-CFU survival was observed when 500 micrograms of BV was administered i.p. 24 h before irradiation. BV did not affect the day 9 CFU-S survival in the bone marrow directly after irradiation. However, 5, 9 and 12 days after irradiation, the number of day 9 CFU-S was almost 2-fold higher in the bone marrow of BV injected mice. Pretreatment with BV protected C57B1/6 mice in a dose-dependent manner from the lethal effect of ionizing radiation. A single dose (50, 100, 250, or 500 micrograms) of bacterial lysate injected i.p. 24 h before 9.5 Gy gamma-rays (LD100/21) protected 16%, 25%, 80%, and 94% of C57B1/6 mice, respectively. The dose reduction factor in the case when the BV (500 micrograms per mouse) was administered at that time was 1.18 (95% CL 1.12, 1.25).

Erythropoietin inhibits apoptosis induced by photodynamic therapy in ovarian cancer cells

Recombinant human erythropoietin is widely used to treat anemia associated with cancer and with the myelosuppressive effects of chemotherapy, particularly platinum-based regimens. Erythropoietin is the principal regulator of erythroid cell proliferation, differentiation, and apoptosis. Recently, the antiapoptotic and proliferative effects of erythropoietin on nonhematopoietic cells were also established. We now show the effect of erythropoietin treatment on the response of A2780 and SKOV3 ovarian carcinoma cell lines to photodynamic therapy (PDT) using hypericin. SKOV3 exhibited an increased resistance to hypericin when cells were treated with erythropoietin. This resistance was reversed by treatment of SKOV3 cells with the specific Janus kinase 2 kinase inhibitor AG490 or the tyrosine kinase inhibitor genistein. These results support a role for the specific erythropoietin-induced Janus kinase 2/STAT signal transduction pathway in PDT resistance. Evidence of erythropoietin signaling was obtained by the demonstration of Akt phosphorylation in both A2780 and SKOV3 cells. Erythropoietin-treated SKOV3 cells exhibited decreased apoptosis induced by hypericin, an effect that was blocked by the phosphoinositide 3-kinase/Akt inhibitor wortmannin. These results may have important implications for ovarian cancer patients undergoing PDT and receiving erythropoietin.

Mechanisms involved in the cell cycle and apoptosis of HT-29 cells pre-treated with MK-886 prior to photodynamic therapy with hypericin

In our previous study we have proved that colon cancer cells HT-29 pre-treated with specific 5-lipoxygenase inhibitor MK-886 became more susceptible to photodynamic therapy (PDT) with hypericin and we also found that this mutual combination induced cell cycle arrest and stimulated onset of apoptosis (Kleban et al., 2007. J. Photochem. Photobiol. B 84, 2). To further explain events associated with MK-886 mediated sensitization of tumor cells toward PDT with hypericin, more detailed study of signaling pathways leading to increase in apoptosis as well as cell cycle perturbations was performed and is presented herein. Intensive accumulation of HT-29 cells in G0/G1 phase of cell cycle led to expression analyses of several G0/G1 checkpoint molecules (cyclin A, cyclin E, cdk-2, pRb). Similarly, accumulation of apoptotic cells invoked analyses of key molecules involved in apoptotic signaling (caspase-3, -8, -9; PARP; Lamin B; Mcl-1; Bax) by Western blotting and caspase activity assay. Long term survival of cells was examined by clonogenicity test. As the effect of PDT is mediated by ROS production, levels of hydrogen peroxides and superoxide anion were monitored by flow cytometric analyses. In addition, an impact of MK-886 on LTB4 production and expression of 5-LOX was monitored. Massive G0/G1 arrest in the cell cycle accompanied by increase in cyclin E level and decrease/absention of cyclin A, cdk-2 and pRb expression indicated incapability for G1/S transition. Minimal changes in cleavage of procaspases observed in cells treated with non-toxic concentrations of either agent alone or their mutual combination were not quite in line with their activity (caspase-3, -8, -9) which was significantly increased mainly in combinations. Treatment with non-toxic concentration of MK-886 had minimal influence over ROS production compared to control cells. In contrast, hypericin alone markedly increased the level of ROS, but no additional effect of MK-886 pre-treatment was detected. Further analyses of particular ROS groups unveiled an impact of increasing MK-886 concentration on superoxide accumulation accompanied with depletion of hydrogen peroxide level within the cells. The clonogenicity test revealed disruption of colony formation after mutual combination of both agents as compared to MK-886 or PDT alone. In conclusion, we presume that stimulation of apoptosis in our experimental model was accomplished preferentially through the mitochondrial pathway, although caspase-8 activation was also noticed. Interestingly, pre-treatment with MK-886 modulated distribution of ROS production in mutual combination with PDT.

Imunomodulative effect of liposomized muramyltripeptide phosphatidylethanolamine (L-MTP-PE) on mice with alveolar echinococcosis and treated with albendazole

The effect of liposomized muramyltripeptide phosphatidylethanolamine (L-MTP-PE) administered separately or with anthelmintic albendazole (ABZ) on cellular immunity of mice with alveolar echinococcosis was studied. The proliferative activity of splenic T and B lymphocytes was the most stimulated after combined L-MTP-PE + ABZ therapy [from weeks 8 to 14 post-infection (p.i.)] that also induced a long-term development of protective Th1 response (the highest serum concentration of IFN-gamma from weeks 8 to 18 p.i.). On the contrary, Th2 response (cytokine IL-5) in infected mice treated with L-MTP-PE was inhibited since week 8 p.i., but a significant long-term decrease in IL-5 concentration was found after combined L-MTP-PE+ABZ therapy until the end of the experiment (until week 26 p.i.). L-MTP-PE stimulated the production of superoxide anion (O2-) by peritoneal macrophages from weeks 8 to 12 p.i., but the highest O2- production was accordingly recorded after therapy L-MTP-PE+ABZ from weeks 8 to 18 p.i. Stimulation of cellular immunity of mice with alveolar echinococcis with L-MTP-PE and an interaction with ABZ's anti-parasitic effect resulted in the greatest and long-term reduction of growth of Echinococcus multilocularis cysts in the host from week 10 p.i. until the end of the experiment.

Modulation of Hypericin Photodynamic Therapy by Pretreatment with 12 Various Inhibitors of Arachidonic Acid Metabolism in Colon Adenocarcinoma HT-29 Cells

One proposal to increase the efficiency of photodynamic therapy (PDT) is to accompany photosensitization with other treatment modalities, including modulation of arachidonic acid (AA) metabolism. The aim of this study was to evaluate the effectiveness of a combined modality approach employing 48 and 24 h pretreatment with various inhibitors of lipoxygenase (LOX; nordihydroguaiaretic acid, esculetin, AA-861, MK-886 and baicalein), cyclooxygenase (COX; diclofenac, flurbiprofen, ibuprofen, indomethacin, SC-560 and rofecoxib) and cytochrome P450-monooxygenase (proadifen) pathways, followed by hypericin-mediated PDT. Cytokinetic parameters like MTT assay, adherent and floating cell numbers, viability and cell cycle distribution analysis were examined 24 h after hypericin activation. Pretreatment of human colon cancer cells HT-29 prior to PDT with 5-LOX inhibitor MK-886 as well as 5, 12-LOX and 12-LOX inhibitors (esculetin and baicalein, respectively) resulted in significant and dose-dependent effects on all parameters tested. Pretreatment with diclofenac, flurbiprofen, ibuprofen and indomethacin, the nonspecific COX inhibitors, promoted hypericin-mediated PDT, but these effects were probably COX-independent. In contrast, application of SC-560 and rofecoxib, specific inhibitors of COX-1 and COX-2, respectively, attenuated PDT. Inhibition of P450 monooxygenase with proadifen implied also the significance of this metabolic pathway in cell survival and cell resistance to hypericin photocytotoxicity. In conclusion, our results testify that application of diverse inhibitors of AA metabolism may have different consequences on cellular response to hypericin-mediated PDT and that some of them could be considered for potentiation of PDT.

Hypericin-induced photocytotoxicity is connected with G2/M arrest in HT-29 and S-phase arrest in U937 cells

Susceptibility of the HT-29 human colon adenocarcinoma cell line and human myeloid leukemia cell line U937 to hypericin-mediated photocytotoxicity was investigated and compared in this study. Cellular parameters as viability, cell number, metabolic activity and total protein amount were monitored in screening experiments with subsequent cell-cycle analysis and apoptosis detection to determine the cellular response of the different tumor types to various concentrations of photoactivated hypericin. The results show concentration dependence of the photosensitizer's cytotoxicity on the studied cell lines, with higher sensitivity of U937 cells. Whereas the two extreme hypericin concentrations (1 x 10(-9) M and 1 x 10(-6) M) resulted in similar changes in all tested cellular parameters on the two studied cell lines, 1 x 10(-8) M and 1 x 10(-7) M hypericin treatment resulted in different responses of the cell lines in all monitored parameters except for viability. Although leukemic cells proved sensitive to both 1 x 10(-8) M and 1 x 10(-7) M hypericin, significant changes on HT-29 cells were detected only after the 1 x 10(-7) M hypericin concentration. Cell-cycle arrest was related to simultaneously occurring apoptosis in colon cancer. Remarkable is the difference in cell-cycle profile where G2/M arrest in colon cancer cells versus accumulation of leukemic cells in the S phase appears. This suggests that hypericin treatment affecting the cell-cycle machinery of different cancer cells is not universal in effect.

Necrosis predominates in the cell death of human colon adenocarcinoma HT-29 cells treated under variable conditions of photodynamic therapy with hypericin

Photodynamic therapy (PDT) represents a new rapidly-developing anticancer approach based on administration of a non- or weakly-toxic photosensitizer and its activation with light of appropriate wavelength. Hypericin, one of the promising photosensitizers, is known to induce apoptosis with high efficiency in various cell line models. However, here we report the prevalence of necrosis accompanied by suppression of caspase-3 activation in colon adenocarcinoma HT-29 cells exposed to an extensive range of PDT doses evoked by variations in two variables -- hypericin concentration and light dose. Necrosis was the principal mode of cell death despite different PDT doses and the absence of anti-apoptotic Bcl-2 expression, even if the same condition induced caspase-3 activity at similar toxicity in HeLa cells. Introduction of Bcl-2 into HT-29 cells invoked caspase-3 activation, changed the Bcl-X(L) expression pattern, increased the apoptosis ratio with no effect on overall toxicity, and supported arrest in the G(2)/M-phase of cell cycle. Since it is known that Bcl-2 suppression in HT-29 is reversible and linked to the over-expression of mutated p53 and also considering our data, we suggest that the mutation in p53 and events linked to this feature may play a role in cell death signalling in HT-29 colon cancer cells.

Histomorphological changes in murine fibrosarcoma after hypericin-based photodynamic therapy

Histomorphological changes in murine fibrosarcoma after photodynamic therapy (PDT) based on the natural photosensitizer hypericin were evaluated. C3H/DiSn mice were inoculated with fibrosarcoma G5:1:13 cells. When the tumour reached a volume of 40-80 mm(3) the mice were intraperitoneally injected with hypericin, either in a single dose (5 mg/kg; 1 or 6 h before laser irradiation) or two fractionated doses (2.5 mg/kg; 6 and 1 h before irradiation with laser light; 532 nm, 70 mW/cm(2), 168 J/cm(2)). All groups of PDT-treated animals with single and fractionated hypericin dosing presented primary vascular reactions including vascular dilatation, congestion, thrombosis and oedema. Two hours after PDT there were necrotic changes with small, rather focal appearance. One day after therapy the necrotic areas were enhanced, often affecting a complete superficial layer of tumour tissue. Necrotic areas were accompanied with inflammation and haemorrhages.

Hsp90 inhibitor geldanamycin increases the sensitivity of resistant ovarian adenocarcinoma cell line A2780cis to cisplatin

Ovarian carcinoma is the leading cause of death among gynecological neoplasms in the world. The chemoresistance is a major obstacle in the effective treatment of ovarian and other cancers. We evaluated the effects of Hsp90 inhibitor geldanamycin (GEL) alone and in combination with cisplatin in cisplatin resistant ovarian adenocarcinoma cell line. Our results showed Akt depletion and S-phase arrest of A2780cis cells after GEL treatment. Combined exposure of A2780cis cells to GEL and cisplatin resulted in greater than additive cytotoxic effect.

Pre-treatment of HT-29 cells with 5-LOX inhibitor (MK-886) induces changes in cell cycle and increases apoptosis after photodynamic therapy with hypericin

It may be hypothesized that the lipoxygenase (LOX) metabolic pathway plays an important role in photodynamic therapy (PDT) of malignant tumours, and modification of this pathway may result in administration of lower doses of photodynamic active agents accompanied by reduced side effects. In this study, we examine in more detail the cytokinetic parameters of human colon adenocarcinoma HT-29 cells pre-treated for 48 or 24h with LOX inhibitor MK-886, followed by PDT induced by hypericin. Based on MTT assay the concentrations of both agents (MK-886 and hypericin) with relatively slight (non-significant) cytotoxic effects were selected. These concentrations were used for combined treatment, where MTT response, total cell number, floating cells quantification, viability, cell cycle progression and DNA synthesis were detected. Hoechst/PI staining, PARP fragmentation and mitochondrial membrane potential (MMP) were evaluated to determine the extent of apoptosis. While MK-886 alone caused mainly necrosis, 48h pre-treatment of cells with MK-886 followed by PDT with hypericin clearly shifted the type of cell death to apoptosis. PDT with hypericin alone caused apoptosis in 19% of the cell population. Some combined modalities significantly potentiated the apoptotic effect (31% of apoptotic cells; 2.5microM MK-886/0.1microM hypericin), i.e., by 60% more than after single treatment with hypericin. Increased apoptosis was confirmed by PARP (116kDa) cleavage to characteristic 89kDa fragments and changes in MMP. Increasing concentration of MK-886 was accompanied by massive changes in the cell cycle progression. Combined treatment with lower concentrations of MK-886 and hypericin increased accumulation of cells in the S phase, accompanied by inhibition of DNA synthesis. Increasing concentration of MK-886 in this combination caused the opposite effect, manifesting significant accumulation of cells in the G0/G1 phase. More pronounced effects were observed after the 48h pre-treatment schedule. This anti-proliferative effect was confirmed by BrdU incorporation. These results indicate that combined treatment involving PDT and LOX inhibitor MK-886 may improve the therapeutic effectiveness of PDT.

Pulmonary fibroblasts stimulate the proliferation of cell lines from human lung adenocarcinomas

Human lung cancer cell lines are widely used to test anticancer drugs. These in-vitro tests, however, preclude the detection of responses to paracrine factors from surrounding stroma. We have cocultured pulmonary fibroblasts CCD-19Lu, from a healthy donor, or HLF-A, from a patient with epidermoid carcinoma of the lung, with two human pulmonary adenocarcinoma cell lines to test the hypothesis that the fibroblasts stimulate the growth of the tumor cells. Both fibroblast cell lines significantly increased the proliferation of the pulmonary adenocarcinoma cell lines in 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide assays, with HLF-A fibroblasts yielding the most pronounced responses. The proliferation of the pulmonary adenocarcinoma cell lines in coculture with fibroblasts was blocked by antibodies against the transforming growth factor-alpha and amphiregulin. In addition, reverse transcription-polymerase chain reaction showed expression of mRNA for amphiregulin and transforming growth factor-alpha in all cell lines, whereas mRNA for the epidermal growth factor was detected only in pulmonary adenocarcinoma cell lines. Western blot analysis revealed that medium containing growth factors released by each fibroblast cell line activated extracellular signal-regulated kinase 1/2 in the both tested pulmonary adenocarcinoma cell lines, but activated Akt kinase only in A549 cells. Assessment of protein levels for cyclin D1 and cyclin E by Western blots demonstrated pronounced increases of both proteins in each pulmonary adenocarcinoma cell line, whereas protein levels for cyclin-dependent kinase inhibitor p21 remained unchanged. Immunocytochemical analysis showed positive immunoreactivity for P-extracellular signal-regulated kinase 1/2, cyclin D1 and cyclin E in pulmonary adenocarcinoma cells cocultured with fibroblasts or exposed to fibroblast-conditioned media. Our data suggest that the growth of pulmonary adenocarcinoma is stimulated by amphiregulin and transforming growth factor-alpha released from pulmonary fibroblasts. This may contribute to the disappointing clinical responses to anticancer drugs, which have shown promise in tests with lung cancer cell lines.

Platinum(IV) complex with adamantylamine overcomes intrinsic resistance to cisplatin in ovarian cancer cells

OBJECTIVES

The resistance of tumor cells to cisplatin remains a major cause of treatment failure in cancer patients. In this study, the ability of Pt(IV) complex with adamantylamine-LA-12 and its reduced counterpart with lower oxidation state Pt(II)-LA-9 to overcome intrinsic cisplatin resistance was investigated.

METHODS

The ovarian adenocarcinoma SK-OV-3 cells were exposed to cisplatin, LA-9, or LA-12 for 72 h and the effects of drug concentrations that caused 10% or 50% inhibition of cell proliferation were determined. After 24-72 h of sustained exposure viability, apoptosis and inhibition of proliferation were analyzed. DNA synthesis and cell cycle analysis were performed simultaneously in order to determine the modulation of cell cycle after platinum complexes treatment.

RESULTS

Lung Resistance-related Protein (LRP/MVP) was detected in SK-OV-3 cells but not in the other two ovarian cancer lines with different sensitivity to cisplatin. LRP/MVP overexpression may be an important factor contributing to intrinsic cisplatin resistance. Interestingly, Pt(IV) complex-LA-12 had approximately 2.7-fold lower IC(50) concentration than LA-9 or cisplatin in SK-OV-3 cells. Moreover, LA-12 caused persistent accumulation of cells in S-phase of the cell cycle while LA-9 and cisplatin treatment-induced S-phase arrest was transient and shifted to G(2)/M-phase at later intervals. Apoptosis seemed to be not the dominant type of cell death caused by such the derivatives, but it was the most intensive after LA-12 treatment.

CONCLUSIONS

We found strong differences between effects of Pt(IV) complex-LA-12 and Pt(II) derivatives-LA-9 and cisplatin on cytokinetic parameters. Overall, LA-12 but not its reduced Pt(II) counterpart LA-9 is the compound effective in p53 null human ovarian cancer cells and it is able to overcome intrinsic cisplatin resistance in these cells.

Photoinduced antitumour effect of hypericin can be enhanced by fractionated dosing

The in vivo antitumour activity of the natural photosensitizer hypericin was evaluated. C3H/DiSn mice were inoculated with fibrosarcoma G5:1:13 cells. When the tumour reached a volume of 40-80mm3 the mice were intraperitoneally injected with hypericin, either in a single dose (5mg/kg; 1 or 6h before laser irradiation) or two fractionated doses (2.5 mg/kg; 6 and 1 h before irradiation with laser light; 532 nm, 70mW/cm2, 168 J/cm2). All tumours in control groups treated with hypericin alone as well as those irradiated with laser light alone had similar growth rates and none of these tumours regressed spontaneously. Complete remission of tumour in photodynamic therapy (PDT)-treated groups was similar (14-17% single dose vs. 33% fractionated dose), but the fractionated schedule of hypericin dosing was found to be more efficient than the single dose, measured by survival assay (p < 0.05). Our experimental model showed that fractionated administration of hypericin can produce a better therapeutic response than single administration.

Hypericin-mediated Photocytotoxic Effect on HT-29 Adenocarcinoma Cells Is Reduced by Light Fractionation with Longer Dark Pause Between Two Unequal Light Doses

The present study demonstrates the in vitro effect of hypericin-mediated PDT with fractionated light delivery. Cells were photosensitized with unequal light fractions separated by dark intervals (1 or 6 h). We compared the changes in viability, cell number, survival, apoptosis and cell cycle on HT-29 cells irradiated with a single light dose (12 J/cm(2)) to the fractionated light delivery (1 + 11 J/cm(2)) 24 and 48 h after photodynamic treatment. We found that a fractionated light regime with a longer dark period resulted in a decrease of hypericin cytotoxicity. Both cell number and survival were higher after light sensitization with a 6-h dark interval. DNA fragmentation occurred after a single light-dose application, but in contrast no apoptotic DNA formation was detected with a 6-h dark pause. After fractionation the percentage of cells in the G1 phase of the cell cycle was increased, while the proportion of cells in the G2 phase decreased as compared to a single light-dose application, i.e. both percentage of cells in the G1 and G2 phase of the cell cycle were near control levels. We presume that the longer dark interval after the irradiation of cells by first light dose makes them resistant to the effect of the second illumination. These findings confirm that the light application scheme together with other photodynamic protocol components is crucial for the photocytotoxicity of hypericin.

In vitro proliferation of fibrosarcoma cells depends on intact functions of lipoxygenases and cytochrome P-450-monooxygenase

Proliferation of mouse fibrosarcoma cells G:5:113 was studied in vitro after affecting particular pathways of arachidonic acid metabolism by selected inhibitors. After 48 hours of cultivation with nonspecific lipoxygenase inhibitors, nordihydroguaiaretic acid (NDGA) and esculetin; a specific 12-lipoxygenase inhibitor, baicalein; and inhibitor of five-lipoxygenase activating protein, MK-886, markedly suppressed the number of cells and induced significant changes in cell cycle distribution in a dose-dependent manner. While proadifen, an inhibitor of cytochrome P-450-monooxygenase, applied in low concentrations, increased the cell number, at higher concentrations, it inhibited cell proliferation and significantly changed the cell cycle. Cyclooxygenase inhibitors, ibuprofen, flurbiprofen, and diclofenac suppressed cell numbers only moderately without any changes in the cell cycle. The occurrence of apoptosis was not significant for any of the selected drugs in comparison with untreated control cells. Moreover, not even one of the drugs caused the specific cleavage of poly (ADP-ribose) polymerase to the 89-kDa fragment, however, a decrease in total amount of this protein was observed after treatment with NDGA and esculetin. We conclude that the proliferation ability of fibrosarcoma cells G:5:113 in vitro depends on intact functions of 5-lipoxygenase, 12-lipoxygenase, and cytochrome P-450-monooxygenases, and that the effects of inhibitors do not include regulation of apoptosis.

Administration of liposomal muramyl tripeptide phosphatidylethanolamine (MTP-PE) and diclofenac in the combination attenuates their anti-tumor activities

The anti-tumor effects of i.p. administered cyclooxygenase inhibitor - diclofenac and i.v. administered liposomal muramyl tripeptide phosphatidylethanolamine (MTP-PE) were investigated using a s.c. growing murine fibrosarcoma tumor. Tumor growth was assessed by measuring tumor volumes and survival of the mice. Both of the drugs were administered either alone or in combination. Repeated application of diclofenac in two schedules (150 microg/mouse/day for 14 consecutive days or 2 x 150 microg/mouse/week for 4 weeks) or application of liposomal MTP-PE (2 x 20 microg/mouse/week for 4 weeks) starting on day 5 after tumor cell transplantation significantly suppressed the tumor growth and increased the percentage of surviving mice. However, the volume of tumors and the survival time in tumor bearing mice treated with the two agents were similar to untreated counterparts. Thus, these data suggest the anti-tumor activity of either of the two drugs is lost when they are used in combination. Hematological examinations confirmed previously observed hematopoiesis-stimulating activities of the drugs when given alone. However, mutually potentiating effects after combined administration of liposomal MTP-PE and diclofenac were observed only exceptionally. Our findings corroborate the recommendation that the interactions of drugs used for the treatment of tumors must be carefully checked, if the drugs are applied in combination.

Hematopoiesis-stimulating and anti-tumor effects of repeated administration of diclofenac in mice with transplanted fibrosarcoma cells

Positive effects of repeated administration of diclofenac, an inhibitor of prostaglandin synthesis, in terms of prevention of tumor development and stimulation of hematopoiesis have been observed in C3H mice transplanted subcutaneously with G:5:113 fibrosarcoma cells. Fourteen-day treatment with diclofenac (3.75 microg/kg/day) started from day 5 after tumor cell transplantation. Measurements of tumors and hematological examinations were performed on day 30. The results strongly suggest the possibility that inhibitors of prostaglandin synthesis (non-steroidal anti-inflammatory drugs) may be used in oncological practice where the observed effects are highly desirable.

Lipoxygenase inhibitors suppress proliferation of G5:113 fibrosarcoma cells in vitro but they have no anticancer activity in vivo

Nordihydroguaiaretic acid (NDGA) and esculetin, both nonspecific inhibitors of lipoxygenases (LOX), were found to suppress expressively the in vitro proliferation of fibrosarcoma cells G5:113 in concentrations ranging from 10 to 50 microM. Subsequent flow-cytometric analysis of the cell cycle showed that both these drugs significantly decreased the percentage proportion of cells in the G0/G1-phase and simultaneously increased significantly this proportion in the S-phase. No apoptosis was detected in the whole range of concentrations studied, from 2.5 to 50 mM. On the contrary, in experiments in vivo, neither NDGA nor esculetin had any curative effect if they were repeatedly injected intraperitoneally (i.p.) into mice bearing tumors growing from subcutaneously (s.c.) transplanted G5:113 cells. Pretreatment of the fibrosarcoma cells with NDGA or esculetin in vitro preceding their s.c. transplantation into mice did not result in suppression of the tumor growth, either. Finally, if G5:113 cells were injected intravenously and the mice were subsequently treated repeatedly with i.p. injections of NDGA, decreased survival and increased number of surface lung metastases were observed in the NDGA-treated group. Thus the suppressive action of inhibitors of LOX on the growth of fibrosarcoma cells in vitro was not reflected in their anti-tumor effects in vivo.

Effect of liposomal muramyl tripeptide phosphatidylethanolamine and indomethacin on hematopoietic recovery in irradiated mice

The effects of liposomal muramyl tripeptide phosphatidylethanolamine (MTP-PE/MLV, radioprotective immunomodulator; 10 mg/kg) and indomethacin (INDO, inhibitor of prostaglandin production; 2 mg/kg) on post-irradiation recovery of hematopoietic functions in mice were investigated. Two agents with distinct radioprotective mechanisms were administered alone or in combination 24 h and 3 h before exposure to 7 Gy (60)Co radiation. In the post-irradiation period (3-14 days) combined pre-treatment of mice accelerated recovery of bone marrow cellularity, weight of spleen and myelopoietic and erythropoietic activity in both hematopoietic organs, compared to treatment with MTP-PE/MLV or indomethacin alone. In the peripheral blood, improved radioprotective effects of combined drug administration were found in the recovery of reticulocytes and platelet count. No further significant differences in the recovery of leukocyte count were observed in the examined groups until post-irradiation day 14. Within the first 3-6 post-irradiation days, the bone marrow and peripheral blood smears of mice pre-treated with indomethacin alone or its combination with MTP-PE/MLV more frequently featured blast cells and large cells with abundant cytoplasm which could be considered the hematopoietic stem cells.

Tumor-host interactions accompanying the growth of the G:5:113 fibrosarcoma in the mouse: possibilities for a new therapeutic approach?

The experiments were aimed at describing in detail some interactions between a solid tumor growing from subcutaneously transplanted G:5:113 fibrosarcoma cells in vivo and its mouse host. The tumor was found to elevate significantly the number of granulocytes in the peripheral blood of the host after having achieved the volume of about 1 cm3 (day 40 after transplantation). Blood plasma from fibrosarcoma-bearing mice stimulated proliferation of progenitor cells for granulocytes and macrophages (GM-CFC) in vitro and suppressed growth of G:5:113 cell population in culture. Interestingly, both effects were observable as early as week 1 when the tumor was still macroscopically invisible and unpalpable. Conditioned medium from cultures of G:5:113 fibrosarcoma cells stimulated proliferation of GM-CFC in vitro. These findings might represent a starting point for studies aimed at designing new therapeutic approaches for the treatment of fibrosarcoma.

The effect of nonsteroidal antiinflammatory drugs ibuprofen, flurbiprofen, and diclofenac on in vitro and in vivo growth of mouse fibrosarcoma

For suppression of primary G:5:113 fibrosarcoma growth, three structurally different cyclooxygenase (COX) inhibitors (ibuprofen, flurbiprofen, and diclofenac) were administered intraperitoneally (i.p.) in two regimens starting on day 5 after tumor-cell inoculation. Repeated application of 0.15 mg/mouse/day during 14 consecutive days significantly suppressed the tumor growth and increased the percentage of surviving mice. Similar tendency, however without significant differences, was observed when animals were given 0.5 mg/day for five consecutive days. These results suggest that a time schedule of drug application is important for the therapeutic effect. Suppressive effect of diclofenac and flurbiprofen on tumor growth was also observed under in vitro conditions. We conclude that suppressive effect of these drugs on tumor growth in vivo comprises both direct effects of COX inhibitors on fibrosarcoma cells and indirect effects that are presumably mediated by extratumoral sources. Our findings encourage the use of COX inhibitors in the therapy of fibrosarcoma.

Effect of acetazolamide on hypericin photocytotoxicity

The photodynamic action of hypericin (HYP) in vitro was evaluated using human leukemic HL-60 and lung carcinoma A549 cell lines. After illumination HYP (1 x 10 (-5) M) reduced the proliferation and/or survival of HL-60 and A549 cells vs. controls to almost to 0 % and 29 %, respectively. A lower concentration of HYP (1 x 10 (-6) M) decreased the proliferation and/or survival only in HL-60 cells. Non-cytotoxic concentrations of the carbonic anhydrase inhibitor acetazolamide (ACTZ) (1 x 10 (-3)-1 x 10 (-6) M) significantly potentiated these effects of HYP (1 x 10 (-6)M) in HL-60, but not in the A549 cell line. The highest concentration of ACTZ (1 x 10 (-3) M) also induced an increase of the subdiploid G 0 /G 1 population in HYP (1 x 10 (-6) M) treated HL-60 cells from 14 % to 24 %. The results indicate that the photogenerated pH drop may participate in the potentiation of the photodynamic action of HYP observed in leukemia cells.

Irradiation induces increased production of haemopoietic and proinflammatory cytokines in the mouse lung

PURPOSE

To investigate cytokine expression following irradiation of mice, predominantly in lung tissue but also in selected other tissues.

MATERIALS AND METHODS

Mice of strain ICR were whole-body (unilaterally) exposed to 3-20 Gy of (60)Co gamma-rays. Colony-stimulating activity (CSA) of lung-conditioned media (LCM), and also other non-haemopoietic and haemopoietic organs, and blood serum of mice was assayed using a GM-CFC bioassay. The production of GM-CSF, IL-6 and TNF-alpha protein in LCM and sera was determined by an ELISA method.

RESULTS

Greatest CSA was detected in conditioned media from the lungs and was induced in a dose- and time-dependent fashion, peaking at 3-9 days after irradiation with a lethal dose of 9 Gy. Conditioned medium prepared from lungs that had been irradiated with a dose of 9 Gy in vitro did not exhibit an increase in CSA. However, whereas the lung-conditioned medium from irradiated mice was found to produce CSA, sera from normal or irradiated mice did not lead to this effect. A significant increase in CSA in sera was observed in the presence of a suboptimal concentration of IL-3, implying that they comprise the co-stimulatory activity (CoSA). The results showed that radiation exposure increased GM-CSF and TNF-alpha protein levels but did not affect IL-6 production in LCM. In contrast, IL-6 and TNF-alpha protein levels in serum were increased after irradiation but no GM-CSF production could be detected.

CONCLUSION

Whole-body irradiation enhances CSA in lungs as well as in other haemopoietic and non-haemopoietic organs. The increase of CSA correlates with increased levels of haemopoietic and proinflammatory cytokines in lung.

Photodynamic therapy of murine fibrosarcoma with topical and systemic administration of hypericin

The in vivo antitumour activity of the natural photosensitizer hypericin was evaluated. C3H/DiSn mice inoculated with fibrosarcoma G5:1:13 cells were intraperitoneally or intratumourally injected with hypericin (5 mg/kg) and 2 hours later the mice were locally irradiated with laser light (488 nm, 150 mW/cm2, 180 J/cm2) when the tumour reached volume of 40-80 mm3 (approximately 17 days after inoculation). Tumours treated with hypericin alone as well as those irradiated with laser light alone have similar growth rates and none of these tumours regressed spontaneously. The mean tumour volume in hypericin-PDT treated groups was significantly lower in comparison to that found in the control group 3-5 weeks after the therapy. A higher proportion of animals with tumour volume less than 5-fold of the initial volume has been observed in both hypericin-PDT treated groups. Complete response to PDT has been observed for 44.4% of the animals with intraperitoneally administered hypericin and for 33.3% of the animals with intratumourally administered hypericin. Complete remission occurred in treated lesions with 3 mm or less in height. Hypericin-PDT significantly increased survival. However, no statistically significant difference in survival rate of animals has been found between the intratumoural and the intraperitoneal schedule of administration of hypericin.

Recovery of peripheral blood cells in irradiated mice pretreated with bacterial extract IRS-19

The effect of antigenic bacterial lysate IRS-19 on the recovery of blood cells was studied in mice injured by a single dose of 7 Gy irradiation. The preirradiation administration of IRS-19 accelerated the recovery of leukocytes, reticulocytes and platelets in peripheral blood. The recovery of leukocytes 9-14 days after irradiation in protected animals was accompanied by a higher level of band forms of granulocytes as well as activated lymphoid and monocytoid cells.

Influence of age and K, Mg aspartate (Cardilan) on murine haemopoiesis

We have studied the effect of age as well as the effect of short-term and long-term intake of K and Mg salts of aspartic acid (Cardilan) on haemopoiesis in ICR mice strain. The cellularity of the bone marrow does not change with aging, but the number of granulocyte-macrophage colony-forming cells (GM-CFC) and also the number of spleen colony-forming units (CFU-S) and erythroid burst-forming units (BFU-E) in two-year-old mice increased in the bone marrow. In two-year-old mice the number of leukocytes decreased in the peripheral blood with aging, mainly as a result of a decrease in mononuclear cells. Short-term drinking (STD) of Cardilan caused increased numbers of CFU-S and BFU-E in bone marrow and increased numbers of reticulocytes in the peripheral blood of one-year old animals (STD/12 months old). In the oldest mice (STD/24) increased weight and cellularity of the spleen and rapid increase of leukocytes and reticulocytes in the peripheral blood was recorded. After long-term drinking (LTD) of Cardilan the number of spleen GM-CFC rose markedly in one-year-old mice (LTD/12) and in two-year-old mice (LTD/24) the number of reticulocytes in the peripheral blood rose. Our results indicate that K and Mg salts of aspartic acid influence erythropoietic activity most widely.

Radioprotection of haemopoietic stem cells by a single injection of bacterial lysate - IRS-19 administered to mice before or after irradiation

Data in this report describes the effect of a single injection of bacterial lysate IRS-19 prior to irradiation of C57Bl/6 mice on recovery of colony-forming cells (CFC) after sublethal and lethal doses of radiation. The injection of IRS-19 promoted an earlier recovery of colony-forming cells in the bone marrow and spleen. For example, 5 and 9 days after 7.5 Gy irradiation, the number of CFU-S per femur was approximately 1.7-2.3-fold higher in IRS-19-injected mice than in saline-injected mice. Also, pretreatment of mice with IRS-19 induced an increase in the number of endogenous haemopoietic stem cells (endoCFU-S). In the postradiation period (5-21 days) significantly increased bone marrow and spleen cellularity and accelerated myelopoietic regeneration (committed progenitor granulocyte-macrophage-colony-forming cells, GM-CFC) in the bone marrow and spleen compared with saline-treated controls. At the time of presumed irradiation, (i.e. 24 h after administration of the drug to the non-irradiated mice), there was no significant difference between the control mice and mice treated with IRS-19 in numbers of femoral and spleen GM-CFC. In contrast, the number of nucleated femoral cells decreased significantly in the group treated with IRS-19. Moreover, treatment with IRS-19 caused a sustained increase in serum colony-stimulating activity which was followed by an enhanced repopulation of GM-CFC in the femoral marrow and spleen. Administration of the agent 24 h prior to irradiation rather than postirradiation appeared most effective with respect to radioprotection. Intravenous rather than i.p. and p.o. was the most effective route of administration in the mouse. Furthermore, single, high-dose injection appeared to be more effective than repeated, lower dose injections. Results suggest that the radioprotective properties associated with the administration of IRS-19 are largely a consequence of the induction of haemopoietic colony-stimulating activities and potentially the activation and/or enhancement of cytokine cascades in the recipient animals. These changes may ultimately impact the cell cycle profile of the haemopoietic cells and therefore their ability to withstand and/or recover from radiation insult.

Effects of immunomodulators on postirradiation recovery in the thymus

The effect of immunomodulatory agents on reparation processes in the thymus was studied in mice injured by a single sublethal or lethal dose of ionizing radiation ranging between 6.5-9.5 Gy. Reparation of thymus weight was not influenced by pretreatment with immunomodulators. Furthermore, the morphological picture did not exhibit appreciable differences between non-protected and protected groups, except for greater proliferation of fibroblasts and macrophages in protected animals.

Effects of cadmium on haemopoiesis in irradiated and non-irradiated mice: 2. Relationship to the number of circulating blood cells and haemopoiesis

The effect of administration of cadmium alone in non-irradiated mice as well as the effect of pre-irradiation administration of cadmium on the reparation processes of haemopoiesis were investigated in mice irradiated by a dose of 7.5 Gy. The pre-irradiation administration of cadmium accelerated the reparation processes in the bone marrow and spleen as well as the number of leukocytes and thrombocytes in the peripheral blood. The administration of cadmium alone caused a temporary weight decrease of the thymus and reduced number of erythrocytes, reticulocytes and haemoglobin values in the peripheral blood. The temporary rapid increase in the number of leukocytes on the 21st day after cadmium administration was investigated.

Effects of cadmium on haemopoiesis in irradiated and non-irradiated mice: 1. Relationship to the number of myeloid progenitor cells

The effects of single subcutaneous injection of cadmium chloride on haemopoiesis in normal (non-irradiated) or irradiated mice were investigated. Cadmium doses used ranged from 1-8 mg/kg body weight Twenty-four hours after treatment with cadmium (doses from 3 to 8 mg/kg) there were no significant changes in bone marrow cellularity and the granulocyte-macrophage progenitor cell (GM-CFC) number per femur in non-irradiated female ICR mice. Similarly, during the 30-day postinjection period bone marrow cellularity and marrow GM-CFC number in mice treated with a cadmium dose of 5 mg/kg were not significantly different from the control values. Cadmium significantly reduced the lethal effects of gamma rays. In addition, increasing the doses of cadmium administered 24 h prior to sublethal irradiation increased the number of endogenous haemopoietic stem cells (endoCFU-S) in a concentration-dependent manner. Pretreatment with cadmium also decreased the radiation damage to endoCFU-S and haemopoietic progenitor cells committed to granulocyte/macrophage development (GM-CFC). The survival of stem cells was higher and the regeneration of cellularity and GM-CFC of irradiated bone marrow was accelerated in mice pretreated with 5 mg Cd/kg body weight in comparison with saline-injected mice.

Combined modality radioprotection: enhancement of survival and hematopoietic recovery in gamma-irradiated mice by the joint use of liposomal muramyl tripeptide phosphatidylethanolamine (MTP-PE) and indomethacin

We have reported previously [Fedorocko, P., Int. J. Radiat., Biol. 65:465, 1994] that liposomal muramyl tripeptidephosphatidyl ethanolamine (MTP-PE/MLV) given prior to irradiation results in augmented hemopoietic recovery and enhanced animal survival as evidenced by increased pluripotent stem cells (CFU-S) and progenitor cells committed to granulocyte and/or macrophage development (GM-CFC) or white blood cells, neutrophil counts, as well as by survival rates of lethally irradiated mice. In this report the effects of liposomal MTP-PE (radioprotective immunomodulator; 10 mg/kg i.p., 24 h before irradiation) and indomethacin (inhibitor of prostaglandin production; 2 mg/kg i.m., 24 h and 3 h before irradiation) were studied. Both of the agents were administered either alone or in combination. The results included the assessment of preirradiation hemopoietic effects of drugs and postirradiation hemopoietic recovery in terms of bone marrow cellularity, number of bone marrow GM-CFC, endogenous spleen colony formation (endoCFU-S), and the determination of the survival of lethally irradiated mice. Experimental evidence elevated by the increased preirradiation numbers of GM-CFC and hydroxyurea kill of GM-CFC as well as a simultaneous significant diminution in bone marrow cellularity indicated that the beneficial action of the combined treatment could be a consequence of increased cell proliferation in the hemopoietic tissue and mobilization with redistribution of stem cells from bone marrow into the circulation. In the postirradiation period (3-14 days), combined pretreatment of mice accelerated myelopoietic regeneration in the bone marrow compared to treatment with MTP-PE/MLV alone or indomethacin alone. Combined administration of MTP-PE/MLV (10 mg/kg, -24 h, i.p.) and indomethacin (2 mg/kg, -24 h and -3 h, i.m.) to mice, prior to lethal irradiation, exerted an additional radioprotective effect and protected 100% of the C57B1/6 mice.

Radioprotective effects of combination broncho-vaxom, a macrophage activator, and indomethacin, an inhibitor of prostaglandin production: relationship to myelopoiesis

The effects of the bacterial extract broncho-vaxom (BV; radioprotective immunomodulator; 500 micrograms/mouse i.p., -24 h) and indomethacin (INDO; inhibitor of prostaglandin production; 2 x 40 micrograms/mouse i.m., -24 h and -3 h) on the post-irradiation recovery of hemopoietic functions in mice were investigated. Both agents were administered either alone or in combination. Endogenous spleen colony formation was increased in all treatment groups, with combination-treated mice exhibiting the greatest effects. Similarly, 24 h after combined administration of BV and INDO (i.e. at the time of presumed irradiation) to the non-irradiated mice granulocyte-macrophage colony-forming cell (GM-CFC) numbers were greater in the bone marrow and spleen. Also, as determined by hydroxyurea injection, there was an increase in the number of GM-CFC in the S-phase of the cell cycle in the bone marrow. However, GM-CFC in the spleen of combination pretreated mice was not stimulated to significant proliferation as compared to GM-CFC in the spleen of mice injected with BV alone. Combined modality treatment was also more effective than single agent treatments in accelerating bone marrow cellularity and GM-CFC regeneration, but not in accelerating GM-CFC regeneration in the spleen. Combined administration of BV and INDO to mice prior to lethal irradiation exerted an additional radioprotective effect and protected 95% of the C57Bl/6 mice.

Administration of the bacterial extract Broncho-Vaxom enhances radiation recovery and myelopoietic regeneration

In the present study, we show that the bacterial extract Broncho-Vaxom (BV, 500 micrograms/mouse; free of endotoxin) has radiation recovery activity when administered i.p. 24 h before sublethal irradiation. In the postirradiation period (5-12 days), pretreatment of mice with BV induced significantly increased bone marrow cellularity and accelerated myelopoietic regeneration (committed progenitor granulocyte-macrophage colony-forming cells; GM-CFC) in the bone marrow compared with saline-treated controls. The earlier hemopoietic recovery in BV-injected mice was not associated with an increase in the number of bone marrow GM-CFC and CFU-S (colony-forming units-spleen) within 24 h after injection. Simultaneously, a significant diminution in bone marrow cellularity occurred. In addition, the percentage of both GM-CFC and CFU-S in the S-phase of the cell cycle was significantly increased 24 h after a single treatment. In our experiments colony stimulating activity (CSA) in the serum of treated mice was not observed within 24 h after injection. Administration of BV 24 h prior to lethal irradiation, resulted in an increase in the number of surviving mice. Combined administration of BV (24 h) and indomethacin (24 h and 3 h) to mice, prior to irradiation, caused an additional radioprotective effect. These results demonstrate that BV stimulates myelopoietic regeneration and suggest a mechanism by which this treatment protects mice from otherwise lethal irradiation.

Liposomal muramyl tripeptide phosphatidylethanolamine (MTP-PE) promotes haemopoietic recovery in irradiated mouse

Pretreatment of C57B1/6 mouse with the macrophage activator muramyl tripeptide phosphatidylethanolamine encapsulated in liposomes (MTP-PE/MLV) induced haemopoietic recovery in subsequently irradiated mouse. An optimal endoCFU-S survival was observed when 200 micrograms MTP-PE/MLV was administered i.p. 24 h before irradiation. MTP-PE/MLV did not affect the day 8 exogenous CFU-S survival in the bone marrow immediately after irradiation. However, 3, 6, 9 and 14 days after irradiation the number of day 8 CFU-S was almost 2 to 4-fold higher in the bone marrow of the MTP-PE/MLV injected mouse. Also, recovery of the GM-CFC pools in femoral bone marrow after irradiation proceeded at a faster rate in the MTP-PE/MLV-treated animal than in control groups. After a single i.p. injection of MTP-PE/MLV to the non-irradiated mouse, the number of CFU-S in bone marrow was not significantly different from controls, whereas the number of GM-CSC was significantly increased. In addition, the percentage of day 8 CFU-S and GM-CFC in S-phase of the cell cycle was significantly increased, as was colony-stimulating activity present in the serum of treated animals. Pretreatment with MTP-PE/MLV protected the C57Bl/6 mouse in a dose-dependent manner from the lethal effects of ionizing radiation. A single dose (100 or 200 micrograms) injected i.p. 24 h, or 100 micrograms MTP-PE/MLV injected i.v. 24 h before 9.5 Gy gamma-rays protected 47, 85 and 59% of C57B1/6 mouse, respectively. The dose reduction factor in the case when the MTP-PE/MLV (200 micrograms per mouse) was administered i.p. at that time was 1.17 (95% CL 1.13, 1.21). Combined administration of MTP-PE/MLV (24 h) and indomethacin (24 and 3 h) to mouse prior to irradiation exerted an additional radioprotective effect.

Radioprotective effects of WR-2721, Broncho-Vaxom and their combinations: survival, myelopoietic restoration and induction of colony-stimulating activity in mice

The possibilities of combined radioprotection, using preirradiation WR-2721 administration and post- or preirradiation Broncho-Vaxom administration in lethally whole-body gamma-irradiated mice were investigated. LD50/30 dose reduction factors (DRFs) for mice treated with WR-2721 (200 mg/kg i.p. 30 min before irradiation), Broncho-Vaxom (25 mg/kg i.p. 24 h before irradiation), or both agents were 1.92, 1.17 and 2.07, respectively. These results demonstrated at least additive radioprotective effects of both agents, manifested in increased survival of irradiated mice. Radioprotection from 17 Gy was optimal when WR-2721 in combination with Broncho-Vaxom was given 30 min before irradiation and Broncho-Vaxom 24 h before or 4-8 h after irradiation. Combined modality treatments were also more effective than individual treatments alone in accelerating the bone marrow GM-CFC restoration. During the first days after irradiation enhanced colony-stimulating activity (CSA) of the lungs was observed in mice with postirradiation injection of Broncho-Vaxom alone or in mice injected with WR-2721 and Broncho-Vaxom (8 h after irradiation), as well as in mice only irradiated.

Pre-irradiation haematological effects of the bacterial extract Broncho-Vaxom and postirradiation acceleration recovery from radiation-induced haematopoietic depression

Effects of the bacterial extract Broncho-Vaxom (BV), free of endotoxin, on haematopoietic parameters of peripheral blood, bone marrow, spleen and thymus were investigated in normal and irradiation-myelosuppressed C57BL/6 mice. BV in normal (nonirradiated) mice induced transient lymphocytopenia and increased granulocytes, particularly neutrophils, six to nine hours after administration. Elevated numbers of peripheral blood macroreticulocytes were observed during the third hour. In the splenic red pulp, enhancing haemopoietic activity, foci of fibroblasts began to appear more frequently from the first hour to 24 h. In lymphatic follicles of the spleen and thymus, the incidence of macrophages or monocytes began to increase three hours after BV application. Twenty-four hours later thymus weight decreased by 27%. In the bone marrow, enhanced proliferation of eosinophils was observed from hour nine, with maximum proliferation at hour 24. BV treatment 24 h before irradiation had a notable radio-protective effect, manifested by accelerated haemopoietic recovery during the postirradiation period. Accelerated myelopoiesis, erythropoiesis and megakaryocytopoiesis resulted in accelerated peripheral blood recovery. However, BV had no effect on thymus reparation as suggested by similar effects in BV protected and BV nonprotected animals during the entire period which followed a 6.5 Gy dose.