Influence of the structure of new anthracycline antibiotics on their biological properties

In the search for new derivatives of anthracycline antibiotics with advantageous biological properties, particularly with lower toxicity and/or higher activity, a series of new analogs of antibiotics applied in therapy such as daunorubicin, doxorubicin, as well as epidoxorubicin and, for comparison, analogs of epidaunorubicin, have been synthesized. Our results show that the new derivatives have antiproliferative activities similar to or higher than the parent antibiotics. The toxicities of these analogs were significantly lower, with LD50 values from 1.8- to 18.4-fold higher than the referential drugs. Cardiotoxicity determinations, using male mice treated with a single dose of 75% of the LD50 values of all tested compounds, indicated that the cardiotoxicity of the new analogs is significantly lower than that of the parent drugs.

Antileukemic activity of glycated fibrinogen-methotrexate conjugates

BACKGROUND

The aim of the study was to compare the antileukemic activity of methotrexate (MTX) conjugates with native and glycated fibrinogen. We expected that conjugates based on glycated fibrinogen would reveal higher antileukemic activity because of decreased plasmin digestibility and a higher retention rate of glycated fibrinogen in the body.

MATERIALS AND METHODS

Fibrinogen was glycated using a high-temperature procedure at 65-85 degrees C. Glycated fibrinogens were examined with respect to their ability to clot and susceptibility to plasmin digestion. Native fibrinogen (F) and fibrinogens glycated at 65 and 73 degrees C (F65 and F73) were conjugated with MTX and tested in mice bearing P388 leukemia, at a dose of 40 mg of MTX per kg of body weight.

RESULTS

Glycated fibrinogens retained their ability to clot. Compared to native fibrinogen, they were more resistant to digestion by plasmin. All tested conjugates revealed higher antitumor activity than the free drug. Increases in average lifespan over the control group were 34% for free MTX, 137% for F-MTX, 151% for F65-MTX and 91% for F73-MTX. The differences between the antitumor activities of all conjugates were not statistically significant.

CONCLUSION

It seems necessary to compare the antitumor activities of MTX conjugates based on native and glycated fibrinogen in different tumor models, to demonstrate the expected differences.

Correlation between VDR expression and antiproliferative activity of vitamin D3 compounds in combination with cytostatics

Calcitriol is a potent antiproliferative agent against various tumour cells in vitro. Its biological activity is mediated by the vitamin D receptors (VDRs). Here, we present the results of a study on vitamin D3 compounds (calcitriol and its analogue PRI-2191) as potential agents in combined antitumour therapy in vitro. Applying antiproliferative SRB and MTT assays, we measured the growth inhibitory effects of vitamin D compounds applied alone or in combination with either cisplatin or doxorubicin. Next, we examined the correlation of this effect with the presence of nVDR (nuclear VDR). The following cancer cell lines were applied: HL-60 (human leukaemia), SW707 (human colon cancer), A549 (human lung cancer), WEHI-3 (mouse leukaemia). The treatment of tumour cells with the combination of vitamin D compounds and cytostatics decreased the inhibitory concentration 50% (IC50) values compared with the effects of cytostatics applied alone. The synergistic effect was positively correlated with nVDR expression.

Phytoestrogens in cancer prevention and therapy--mechanisms of their biological activity

Numerous epidemiological studies suggest that diets rich in phytoestrogens (PE), particularly soy and unrefined grain products, may be associated with low risk of some cancers, especially steroid hormone-dependent, e.g. breast and prostate cancers. Epidemiological, in vitro, animal and human studies have investigated the mechanisms involved in PE biological actions, including steroid hormone activity, effects on cell growth, antioxidant activities, inhibition of chemical carcinogenesis and influences on modulators of cancer risk. The question of whether PE may be used as an anticancer therapeutic and/or chemopreventive agents remains unanswered. Clearly, much more information is required, especially concerning the safety of their use. It seems extremely difficult to predict the effects of various PE mixtures present in different human diets. Long-term studies (in vitro, animal, clinical and epidemiological) with well standardized PE preparations are necessary to assess the potential beneficial and adverse effects. With our current state of knowledge, we cannot conclude whether consumption of soy, SIF (soy isoflavones)-supplemented food or the use of particular isoflavones as therapeutics will have positive, null or even adverse effects on cancer (particularly, steroid hormone-dependent) risk and treatment. A brief review of the effects (preventive, antitumor as well as carcinogenic and tumor-stimulating) of PE on various tumor types is presented.

Activity of Bacteriophages in Murine Tumor Models Depends on the Route of Phage Administration

Previously we investigated the anticancer activity of bacteriophage preparations in various murine tumor models. We demonstrated the antimetastatic activity of purified and nonpurified bacteriophage preparations injected intraperitoneally (IP). However, in solid tumors we observed antitumor activity of purified bacteriophages, but the lysates (raw preparations obtained by culturing phages with bacteria) stimulated tumor growth. In this article we present a comparison of the antitumor activity of bacteriophages after oral (per os, PO) and IP administration of lysates and purified preparations. Our observations indicate that PO application of a bacteriophage preparation is safer and at least as effective as IP. Stimulation of solid tumors by lysates administered orally was not observed, and bacteriophages applied PO were more effective in inhibiting metastases formation. These observations are of great importance in any consideration of possible therapeutic applications of bacteriophages. The role of the route of bacteriophage administration should be considered in the context of the effectiveness and safety of such therapies.

Synthesis, structure, and cytostatic properties of new olivacine derivatives

Starting from 2-(6-methoxy-1-methyl-9H-carbazol-2-yl)ethylamine and 6-methylpicolinic acid, 9-methoxy-5-methyl-1-(6-methylpyridin-2-yl)-6H-pyrido[4,3-b]carbazole 10 and its 6-alkylderivatives 12-17 were obtained. The newly obtained compounds showed significant cytostatic activity against cultured L1210 cells and high cytotoxicity towards various human tumor cell lines.

[TRPM7: a protein responsible for magnesium homeostasis in a cell]

Magnesium is an important cofactor in biological processes. For many years it has been considered that magnesium homeostasis in a cell is regulated by its eflux from a cell and not by its influx. It has also been considered that the Na+/Mg2+ antiport plays the main role. In recent years, many experiments have been carried out to understand the mechanisms of Mg2+ transport in an organism. These experiments have led to some new conclusions. It was confirmed that the level of magnesium in a cell is probably also regulated by its influx to the cell. One of the last scientific findings is the discovery of the TRPM (transient receptor potential melastatin) protein family. TRPM6 and TRPM7, bifunctional proteins with kinase and ion channel activities, are responsible for magnesium homeostasis. The discovery of these proteins led to a better understanding of magnesium homeostasis. It was confirmed that TRPM6 protein is responsible for homeostasis in the whole organism and that TRPM7 may regulate the level of magnesium in the cell. TRPM7 also has other functions. One of those newly recognized is the phosphorylation of annexin 1. However, many activities and functions of TRPM7 have not yet been described. This paper is a review of knowledge of TRPM7 transmembrane protein, which is responsible for the magnesium homeostasis in the cell. It briefly presents the main functions and structure of TRPM7. It also describes the mechanisms of its biological activity.

Side-chain-modified analogs of calcitriol cause resistance of human HL-60 promyelocytic leukemia cells to drug-induced apoptosis

Calcitriol and some of its analogs have antiproliferative activity, but at the same time, can cause resistance to apoptosis induced by known cytostatic drugs. In this paper, we examined the effects of treatment with calcitriol or its side-chain-modified analogs, analog of Vitamin D2, coded PRI-1906, with monohomologated and unsaturated side-chain and the analog of Vitamin D3, coded PRI-2191, with (24R) hydroxyl group, and those of known cytostatics (genistein, etoposide, doxorubicin, cisplatin, and taxol) on the apoptosis of HL-60 promyelocytic leukemia cells. HL-60 cells were incubated in three different sequences: (1) pre-treatment with calcitriol or its analogs and then treatment with cytostatics; (2) pre-treatment with cytostatics and then treatment with calcitriol; (3) simultaneous treatment with calcitriol and cytostatics. Apoptosis was examined either by DNA fragmentation in agarose gel electrophoresis or by cell-cycle analysis in a FACS Calibur flow cytometer. We showed that pre-treatment with calcitriol or one of its side-chain-modified analogs PRI-1906 or PRI-2191 caused resistance of HL-60 promyelocytic leukemia cells to genistein-, doxorubicin-, cisplatin-, and taxol-induced apoptosis. Simultaneous exposure of HL-60 cells to calcitriol and drug caused a significant decrease in the apoptotic level of HL-60 cells compared with cells treated with drug alone. The pre-treatment of HL-60 cells with drug and then treatment with calcitriol did not increase the level of apoptosis compared with the drug effect alone. These results indicate the potential limitations of calcitriol analogs for treatment of leukemia.

[Biological activity of calcitriol and its new analogues -- potential therapeutic applications]

Calcitriol is effective not only in the regulation of calcium-phosphate homeostasis, but also in promoting the differentiation and inhibition of proliferation of various cells. Calcitriol seems to be a potent drug with various therapeutic applications, such as regulation of calcium-phosphate homeostasis and treatment of psoriasis, autoimmune diseases, and cancer. Since clinical use of calcitriol is largely limited, due to its undesirable side effect of hypercalcemia, numerous calcitriol analogues have been synthesized to obtain compounds with better therapeutic profiles. This paper summarizes the current state of knowledge concerning the cellular mechanisms of calcitriol's biological activity and their clinical implications. Such medical application includes treatment (as a single-drug or in combination) of osteoporosis, renal osteodystrophy, psoriasis (calcipotriol or tacalcitol ointment), autoimmunological diseases (including multiple sclerosis), and some cancers. The efforts to obtain new vitamin D3 analogues are also briefly reviewed. The structures and roles of vitamin D receptors in the biological effects of calcitriol and its analogues are discussed.

Magnesium deficiency inhibits primary tumor growth but favors metastasis in mice

The results of several experimental and epidemiological studies have shown an inverse correlation between Mg status and the risk of some cancers. However, relationship between magnesium and cancer is complex. The aim of our work was to examine the precise effect of Mg deficiency on transplantable mouse tumor growth and metastasis. The results obtained indicate a significant retardation of primary tumor growth (up to 70%) in mice receiving Mg-deficient diet. However, Mg repletion caused in these mice significant increase of primary tumor burden. Analysis of cell cycle distribution showed a reduced percentage of cells in the S phase and an increase of cells in the G(0)/G(1) phase of the cell cycle in LLC tumors caused by Mg deficiency. This is in agreement with the effect of low Mg level on cell growth observed in vitro. Interestingly, in mice inoculated with LLC cells and receiving low-magnesium diet, a higher metastatic potential was observed as compared to control mice. In conclusion, our results demonstrate a direct role of magnesium in tumor growth and also point at deleterious effect of low magnesium status on tumor metastasis.

Changes in gene expression in the lungs of Mg-deficient mice are related to an inflammatory process

It has been well documented that experimental hypomagnesemia in rodents evokes, as an early consequence, an inflammatory response. This also leads to the activation of cells producing reactive species of oxygen and, as a result, to the oxidative damage of tissues. Several studies have shown that lungs might be a specific target of Mg deficiency. Here, we report that 3 weeks of Mg deficiency in mice resulted in inflammatory processes in the lungs, including interstitial and perivascular pneumonia, manifested by the infiltration of leukocytes, plasmocytes and histiocytes, as well as the phenomenon of disseminated intravascular coagulation (DIC). These phenomena were accompanied by changes in gene expression assessed by cDNA array. In this study we identified 26 genes significantly changed by Mg deficiency, mostly involved in the anti-oxidative response, regulation of cell cycle and growth, apoptosis as well as cell-cell and cell-matrix interactions. We conclude that these changes are related to the phenomena of inflammatory and oxidative processes and consecutive remodeling occurring in the tissues as a result of Mg deficiency. This may have implications for at least several lung pathologies, including allergies, asthma, SIDS (Sudden Infant Death Syndrome) or facilitate formation of lung metastases.

Genistein alone or combined with cyclophosphamide may stimulate 16/C transplantable mouse mammary cancer growth

Among the many potential antiangiogenic agents now in various stages of preclinical or clinical study, genistein (GEN) has generated wide interest being because of its natural origin (soybeans) and epidemiological studies showing the cancer chemopreventive effects of soybean consumption. In this paper the in vivo effects of GEN applied either alone or together with cyclophosphamide on the growth of mouse transplantable mammary carcinoma (16/C) transplanted either orthotopically or ectopically is presented. The growth of 16/C mouse mammary cancer transplanted subcutaneously (s.c.) or into the mammary gland (orthotopically-orth.) was stimulated by GEN administered from day 4 after tumor cell inoculation. Such stimulation was not observed when the treatment with GEN was started at day 12 after cell inoculation. Stimulation of tumor growth by GEN was markedly higher in mice transplantedorth. than in those transplanted s.c.. However, GEN did not affect the expression of estrogen (ER)and progesterone receptors (PgR) in the orthotopic model of 16/C cancer. In the case of subcutaneously growing tumors, treatment with GEN lowered (2-fold) the expression of both ER and PgR. In the interpretation of these results, the pleiotropic (including hormonal and antiproliferative), sometimes opposing effects of genistein in vivo should be considered. It seems rather reasonable to exclude breast and, perhaps, other hormone-dependent cancers from the treatment and chemoprevention with soy-derived phytoestrogens until its mechanism(s) of action on various cancer cells is completely understood.

Anticancer activity of bacteriophage T4 and its mutant HAP1 in mouse experimental tumour models

BACKGROUND

Previously, we have shown the ability of the bacteriophage T4 and its substrain HAP1 (selected for a higher affinity to melanoma cells) to reveal antimetastatic activity in a mouse melanoma model. Here, we investigated the potential phage anticancer activity in primary tumour models.

MATERIALS AND METHODS

Mice were inoculated subcutaneously with B16 or LLC cells (collected from in vitro culture). Bacteriophages T4 and HAP1 were injected intraperitoneally daily (8 x 10(8)pfu/mouse, except the experiment concerning the dose-dependence).

RESULTS

Treatment with purified preparations of bacteriophage T4 resulted in significant reduction of tumour size, the effect being dose-dependent. HAP1 was more effective than T4 and its activity was also dose-dependent. Parallel experiments with non-purified bacteriophage lysates resulted in significant stimulation of tumour growth.

CONCLUSION

These data suggest that purified bacteriophages may inhibit tumour growth, a phenomenon with potentially important clinical implications in oncology.

Toxicity and antineoplastic effect of (24R)-1,24-dihydroxyvitamin D3 (PRI-2191)

Many efforts have been made to obtain active and less toxic Vitamin D analogs for new clinical applications. The results of previous studies demonstrated the efficacy and safety of topical treatment of psoriasis with one of these analogs, 1,24-dihydroxyvitamin D(3), tacalcitol (1,24-(OH)(2)D(3)). In the present study, we evaluated the toxicity and antitumor effect of this analog. Lethal toxicity of 1,24-(OH)(2)D(3) after s.c. injection was significantly lower than that of calcitriol. No significant differences were observed in the toxicity of the analogs when administered p.o. Calcium levels in the serum of mice treated with calcitriol were significantly higher (111%) than those in mice treated with 1,24-(OH)(2)D(3) (89%) at 5 day after the first s.c. (10 microg/kg/day) administration in comparison to the control (healthy, untreated animals). Oral administration increased the calcium level by 78% for calcitriol and only to 47% over the control for 1,24-(OH)(2)D(3). Parallel administration of clodronate prevented the calcitriol- and 1,24-(OH)(2)D(3)-induced lethal toxicity and also prevented increase in calcium levels. Single therapy with calcitriol did not affect tumor growth in the 16/C mouse mammary cancer model. In contrary, 1,24-(OH)(2)D(3) alone reduced tumor volume to 41% of control. Cisplatin alone did not affect growth of 16/C tumor in these conditions. The growth of tumors in the presence of cisplatin was inhibited by 1,24-(OH)(2)D(3) but not by calcitriol. Interestingly, the inhibition of tumor growth in cisplatin-treated mice by 1,24-(OH)(2)D(3) was greater, than that observed in mice treated with this analog alone. In conclusion, 1,24-(OH)(2)D(3) revealed higher antitumor and lower calcemic activity and toxicity than calcitriol. Application of biphosphonates along with Vitamin D analogs is sufficient to overcome the calcemic and toxic side effects of the proposed treatment.

New insights into the possible role of bacteriophages in transplantation

Due to the increasing prevalence of drug-resistant bacterial infections in the "post-antibiotic era," bacteriophages (bacterial viruses, BP) may be useful to administer to transplant recipients without exposing them to an increased risk of rejection, which occurs consequent to some viral infections. Herein we present evidence that at least some coliphages (T4) do not pose such risk. Interestingly, they may produce immunosuppressive effects extending transplant survival. Our data suggest that BP may be used in clinical transplantation to treat drug-resistant bacterial infections and perhaps as an adjunct to immunosuppressive therapy.

Synthesis and in vitro cytostatic activity of some new 1,3-(oxytetraethylenoxy)-cyclotriphosphazatriene derivatives

A series of cyclophosphazene crown ether derivatives bearing aziridinyl (ethylene imine) units and also 2-naphthyl or anthraquinone groups as co-substituents has been synthesized and their cytostatic activity against the panel of eight cancer cells in vitro has been studied. The substituents used exhibit different activities: alkylation (aziridinyl groups) and intercalation (naphtyl, anthraquinone groups) against DNA. These both interactions are supposed to enhance the efficiency of the cyclophosphazene crown ether derivatives studied as cytotoxic agents.

New analogues of laminin active fragment YIGSR: synthesis and biological activityin vitro andin vivo

Eleven analogues of the laminin pentapeptide amide fragment Tyr-Ile-Gly-Ser-Arg-NH2 (YIGSR-NH2) corresponding to a B1 chain fragment of the glycoprotein laminin have been synthesized by the solid phase method, and their biological activity has been studied in vitro by a cell adhesion assay: all of them inhibited the adhesion of LLC tumor cells to laminin. The analogues were found to be more resistant to enzymatic degradation in human serum than YIGSR-NH2 itself. Analogue DatIGSHar-NH2 was selected for an experimental pulmonary metastasis assay in vivo: it had higher antimetastatic activity than YIGSR-NH2.

The tumorigenic potential of human CX-1 colon adenocarcinoma cells depends on carcinoembryonic antigen (CEACAM5) expression

It was shown that CEACAM5 can mediate cell-cell adhesion through homotypic and heterotypic interactions; however, its role in the expression of the malignant phenotype remains obscure. To study whether the formation of both primary tumors and metastases is directly related to the presence or absence of CEACAM5, we applied the antisense RNA strategy. By transfecting human CX-1.1 colon carcinoma cells with CEACAM5 antisense-expressing vector or with the vector itself, cell variants with a highly decreased expression of CEACAM5 were obtained. Profound differences in proliferative abilities among parental and obtained subclones of CX-1.1 cells were revealed when cells were implanted subcutaneously into nude mice. In contrast to their highly tumorigenic parental CX-1.1 cells (with high expression of membrane-bound and secreted CEACAM5), two subclones (3E and AS6Q) with substantially decreased expression of membrane-bound and secreted CEA showed a considerably diminished growth rate. Even more striking results were obtained with AS8Q cells, producing a residual amount of this glycoprotein. However, 3B cells (producing a large amount of secreted CEACAM5) did not differ significantly in their tumorigenic properties from CX-1.1 cells. Our experiments performed in nu/nu mice suggest that CEACAM5 supports the growth of primary tumors, but is not involved in the formation of metastases by colon cancer cells.

[Genistein: a soy isoflavone revealing a pleiotropic mechanism of action - clinical implications in the treatment and prevention of cancer]

Genistein, a naturally occurring isoflavonoid, displays antitumor, antimetastatic and antiangiogenic properties, described in various experimental in vitro and in vivo models. The results of several epidemiological studies suggest that soybean consumption may contribute to lower incidence of breast, colon, prostate, thyroid, and head and neck cancers. This protective effect of soy consumption is attributed, among others, to genistein. On the other hand, genistein may enhance the proliferation of some estrogen-positive human breast cancer cells in vivo and the growth of mammary gland and mammary cancer cells in athymic mice. In this paper, various aspects of the diverse biological activities of genistein and their potential clinical implications, especially in the treatment and prevention of cancer, are reviewed and discussed.

Synthesis and antiproliferative activity in vitro of 2-aminobenzimidazole derivatives

A novel series of Schiff bases 1-11, the derivatives of 2-aminobenzimidazole and substituted aromatic aldehydes, has been synthesised. Compounds 1-11 reduced by NaBH(4) formed 2-benzylaminobenzimidazoles 12-21. 2-(o-Bromobenzylamino)benzimidazole (15) acylated by cinnamoyl chloride gave 2-(o-bromobenzylamino)-1-cinnamoylbenzimidazole (22). Long heating of 15 and 19 with p-nitrocinnamoyl or cinnamoyl chloride led to the formation of pyrimido[1,2-a]benzimidazol-4-ones 23 and 24. The structures of 1-24 were identified by the results of elemental analysis and their IR, (1)H NMR and MS spectra. Among the compounds 1-24 evaluated for their antiproliferative activity in vitro, 16, 19, 20 and 22 exhibited cytotoxic activity against the cells of human cancer cell lines, namely SW707 (rectal), HCV29T (bladder), A549 (lung) and T47D (breast cancer).

Multinuclear NMR spectroscopy and antitumor activity of novel platinum(II) complexes with 5,7-disubstituted-1,2,4-triazolo[1,5- a ]pyrimidines

Novel platinum(II) complexes with 5,7-disubstituted-1,2,4-triazolo[1,5-a]pyrimidines have been synthesized and characterized by infrared and multinuclear magnetic resonance spectroscopic techniques (1H, 13C, 15N, 195Pt). The complexes are of two types: [PtCl2(L)2] and [PtCl2(NH3)(L)], where L=5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine (dptp) and 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp). Significant 15N NMR upfield shifts (92-95 ppm) were observed for N(3) atom indicating this nitrogen atom as a coordination site. The molecular structure suggest that Pt(II) ion has the square planar geometry with N(3) bonded 5,7-disubstituted-1,2,4-triazolo[1,5-a]pyrimidines, N-bonded second ligand (NH3 for cis-[PtCl2(NH3)(L)] or, respectively, 5,7-disubstituted-1,2,4-triazolo[1,5-a]pyrimidines for cis-[PtCl2L2]) and two cis chloride anions. The antiproliferative activity in vitro of complexes (1-4) have been tested against the cells of four human cell lines: SW707 rectal adenocarcinoma, A549 non-small cell lung carcinoma, T47D breast cancer and HCV29T bladder cancer. The results indicate a moderate antiproliferative activity of (4) against the cells of rectal, breast and bladder cancer and a marked and selective cytotoxic effect of (1-3) against the cells of all studied human cancer lines.

Role of copper in tumour angiogenesis--clinical implications

The formation of new blood vessels is the initial step in progressive tumour development and metastasis. The first stage in tumour angiogenesis is the activation of endothelial cells. Copper ions stimulate proliferation and migration of endothelial cells. It has been shown that serum copper concentration increases as the cancer disease progresses and correlates with tumour incidence and burden. Copper ions also activate several proangiogenic factors, e.g., vascular endothelial growth factor, basic fibroblast growth factor, tumour necrosis factor alpha and interleukin 1. This review concerns a brief introduction into the basics of tumour blood vessel development as well as the regulatory mechanisms of this process. The role of copper ions in tumour angiogenesis is discussed. The new antiangiogenic therapies based on a reduction of copper levels in tumour microenvironment are reviewed.