The effects of staphylococcal bacteriophage lysates on cancer cells in vitro.

Bacteriophages constitute a serious alternative to antibiotic therapy of bacterial infections. They are also extremely numerous entities: phages can be found in almost all places on Earth and are constantly present in human and animal bodies. Observations of the effect of therapeutic staphylococcal phages and their bacterial hosts on melanoma migration in vitro are reported in this article. Together with bacteriophage preparations, disrupted Staphylococci (host strains) were investigated to compare the effects of bacteria with those of bacteriophages. Migration was decreased by all the investigated preparations in various ways and this was rather due to the activity of the bacterial components. Importantly, none of the investigated bacteriophage or bacterial preparations induced an increase in the migration activity of melanoma cells, which is important from the perspective of the therapeutic use of phage lysates. The possible presence of staphylococcal enterotoxins in the therapeutic bacteriophage preparations was also verified. All the studied therapeutic bacteriophage preparations were negative for the Staphylococcal enterotoxins A, B, C, D, and E (i.e., the enterotoxin content was less than 0.2-0.5 ng/ml).

Antitumor effect of combined treatment of mice with cytostatic agents and bacteriophage T4.

The past few years have shown significant resurgent interest in the old concept of bacteriophage therapy. Some research groups continue to develop whole bacteriophage preparations as alternatives to antibiotic antibacterial treatment. However, improvements in the methods of purification of phage preparations open new opportunities in the successful treatment of antibiotic-resistant bacterial infections. An open question remains on whether bacteriophage preparations (BP) can be safely applied in antibacterial treatment of patients suffering from infections as a consequence of immunosuppression caused by anticancer chemotherapy. The aim of this study was to evaluate the potential modulating effect of bacteriophage T4 preparations administered to mice bearing s.c. or i.v. inoculated B16 melanoma and treated with conventional anticancer drugs, i.e. cyclophosphamide (CY), cisplatin (CPt) or 5-fluorouracil (5-FU). Treatment of mice with (BPT) T4 preparation slightly potentiated the antimetastatic effect of CY. Importantly, no combination of phage-cytostatic treatment resulted in a decrease in the antimetastatic or antitumour effects of an applied drug. This suggests the possibility of safe combination of bacteriophage preparations with popular antitumour drugs.

Bacteriophage interactions with phagocytes and their potential significance in experimental therapy.

Bacteriophages are among the most numerous creatures on earth and they are omnipresent. They are thus in constant natural contact with humans and animals. However, the clinical and technological use of bacteriophages has also become more frequent, which is why all aspects of phage-mammal interactions need to be explored. Bacteriophages are able to interact with mammalian phagocytes. They may inhibit the phagocytosis of bacteria, but they may also undergo phagocytosis themselves. The ability of bacteriophages to reduce reactive oxygen species production by polymorphonuclear leukocytes in the presence of bacteria or their endotoxins was also confirmed. Studies show that the high immunogenicity of bacteriophages may also be employed in anti-tumor treatment. The present knowledge of phage interactions with cellular components of the mammalian immune system is sparse and insufficient, especially considering the increasing interest in the application of these viruses in human life. We believe that continuation of such research is indispensable.

The effect of bacteriophages T4 and HAP1 on in vitro melanoma migration.

BACKGROUND: The antibacterial activity of bacteriophages has been described rather well. However, knowledge about the direct interactions of bacteriophages with mammalian organisms and their other, i.e. non-antibacterial, activities in mammalian systems is quite scarce. It must be emphasised that bacteriophages are natural parasites of bacteria, which in turn are parasites or symbionts of mammals (including humans). Bacteriophages are constantly present in mammalian bodies and the environment in great amounts. On the other hand, the perspective of the possible use of bacteriophage preparations for antibacterial therapies in cancer patients generates a substantial need to investigate the effects of phages on cancer processes. RESULTS: In these studies the migration of human and mouse melanoma on fibronectin was inhibited by purified T4 and HAP1 bacteriophage preparations. The migration of human melanoma was also inhibited by the HAP1 phage preparation on matrigel. No response of either melanoma cell line to lipopolysaccharide was observed. Therefore the effect of the phage preparations cannot be attributed to lipopolysaccharide. No differences in the effects of T4 and HAP1 on melanoma migration were observed. CONCLUSION: We believe that these observations are of importance for any further attempts to use bacteriophage preparations in antibacterial treatment. The risk of antibiotic-resistant hospital infections strongly affects cancer patients and these results suggest the possibility of beneficial phage treatment. We also believe that they will contribute to the general understanding of bacteriophage biology, as bacteriophages, extremely ubiquitous entities, are in permanent contact with human organisms.

The influence of 1,25-dihydroxyvitamin D3 and 1,24-dihydroxyvitamin D3 on alphavbeta3 integrin expression in cancer cell lines.

Integrins are cell-surface receptors engaged in important cancer invasion processes, such as adhesion, migration, proliferation and differentiation. The aim of this study was to evaluate the effect of 1,25-dihydroxyvitamin D3 (calcitriol) and its metabolite 1,24-dihydroxyvitamin D3 (PRI-2191) on alphavbeta3 integrin expression in various cancer cell lines. The expression levels of the beta3 and alphav integrins were reduced only in the WEHI-3 and LLC cell lines by the two compounds. Calcitriol or PRI-2191 treatment caused differentiation of WEHI-3 mouse leukemia cells, but apoptosis of LLC cells. WEHI-3 and LLC cells exposed to calcitriol or PRI-2191 lost their migratory and adhesive potentials. The inhibition of migratory potential was higher in the LLC cells than in the WEHI-3 cells and appeared to correlate with the increased down-regulation of alphavbeta3 integrin by calcitriol or PRI-2191. The observed in vivo effects (antitumor and antimetastatic) in mice bearing subcutaneously transplanted LLC cancer are possibly associated with inhibited migratory potential as a consequence of the lowered integrin expression caused by calcitriol or PRI-2191.

Bacteriophage preparation inhibition of reactive oxygen species generation by endotoxin-stimulated polymorphonuclear leukocytes.

It has been known that administration of antibiotics may lead to excessive release of bacterial endotoxins and complicate clinical course of patients with Gram-negative infections. This concern may also apply to phages. Endotoxin may in turn activate neutrophils to produce reactive oxygen species (ROS) that are believed to play an important role in the pathogenesis of multiple organ dysfunction in the course of sepsis. We showed that a purified T4 phage preparation with low-endotoxin content could significantly diminish the luminol-dependent chemiluminescence (CL) of peripheral blood polymorphonuclear leukocytes (PMNs) both stimulated by lipopolysaccharides (LPSs) isolated from different Escherichia coli strains. This effect was also observed for live bacteria used for PMNs stimulation and was independent of bacterial susceptibility for T4-mediated lysis. Our data suggest, that phage-mediated inhibition of LPS- or bacteria-stimulated ROS production by PMNs may be attributed not only to phage-PMNs interactions, but also to phage-LPS interactions and bacterial lysis (in case of homologous phage). Interestingly, the T4 preparation did not influence ROS formation by PMNs stimulated with PMA. This suggests that the observed phenomena are also dependent upon the nature of activator. Bacteriophage-mediated inhibition of ROS formation by cells exposed to endotoxin provides new evidence for possible interactions between phages and mammalian cells. It helps in understanding the role of phages in our environment and may also be of important clinical significance.