Blocking of lectin-like adhesion molecules on pulmonary cells inhibits lung sarcoma L-1 colonization in BALB/c-mice

Phylogenetic analysis and a review of the history of the accidental phytoplankter, Phaeodactylum tricornutum Bohlin (Bacillariophyta)

The diatom Phaeodactylum tricornutum has been used as a model for cell biologists and ecologists for over a century. We have incorporated several new raphid pennates into a three gene phylogenetic dataset (SSU, rbcL, psbC), and recover Gomphonemopsis sp. as sister to P. tricornutum with 100% BS support. This is the first time a close relative has been identified for P. tricornutum with robust statistical support. We test and reject a succession of hypotheses for other relatives. Our molecular data are statistically significantly incongruent with placement of either or both species among the Cymbellales, an order of diatoms with which both have been associated. We believe that further resolution of the phylogenetic position of P. tricornutum will rely more on increased taxon sampling than increased genetic sampling. Gomphonemopsis is a benthic diatom, and its phylogenetic relationship with P. tricornutum is congruent with the hypothesis that P. tricornutum is a benthic diatom with specific adaptations that lead to active recruitment into the plankton. We hypothesize that other benthic diatoms are likely to have similar adaptations and are not merely passively recruited into the plankton.

Evaluation of the Antineoplastic Activity of L-rhamnose in vitro. A Comparison with 2-deoxyglucose

The effect of unsubstituted deoxyhexoses, 2-deoxy-D-glucose (2-DG) and L-fucose, on tumor cells has been reported in several papers throughout the last decades. That of a similar deoxysugar, L-rhamnose, which is synthesized in bacteria and plants but not in animal cells, has until today not been explored. In the present study, we examined the effect of L-rhamnose on DNA and protein synthesis, growth and the potential induction of apoptosis of tumor cells in vitro. Using 2-DG for comparison, we studied the effect of L-rhamnose in concentrations up to 20 (32 resp.) mmol/l on the initial velocity of the incorporation of labeled precursors of DNA and proteins in short term cultures of both mouse Ehrlich ascites tumor (EAT) and human HL-60 cells in vitro, and further, on cell proliferation and apoptosis induction in HL-60 cells. Neither cytotoxic nor cytostatic effects of L-rhamnose were observed with the exception of slightly pronounced inhibition of DNA synthesis in EAT cells. From the lacking inhibition of the protein synthesis it can be considered that L-rhamnose does not interfere with energy metabolism, at least not in a similar manner as 2-DG.

Modeling of deoxy- and dideoxyaldohexopyranosyl ring puckering with MM3(92)

Extensive variations of the ring structures of three deoxyaldohexopyranoses, L-fucose, D-quinovose, and L-rhamnose, and four dideoxyaldohexopyranoses, D-digitoxose, abequose, paratose, and tyvelose, were studied by energy minimization with the molecular mechanics algorithm MM3(92). Chair conformers, 4C(1) in D-quinovose and the equivalent 1C(4) in L-fucose and L-rhamnose, overwhelmingly dominate in the three deoxyhexoses; in the D-dideoxyhexoses, 4C(1) is again dominant, but with increased amounts of 1C(4) forms in the alpha anomers of the three 3,6-dideoxyhexoses, abequose, paratose, and tyvelose and in both alpha and beta anomers of the 2,6-dideoxyhexose D-digitoxose. In general, modeled proton-proton coupling constants agreed well with experimental values. Computed anomeric ratios strongly favor the beta configuration except for D-digitoxose, which is almost equally divided between alpha and beta configurations, and L-rhamnose, where the beta configuration is somewhat favored. MM3(92) appears to overstate the prevalence of the equatorial beta anomer in all three deoxyhexoses, as earlier found with fully oxygenated aldohexopyranoses.

Importance of lectins for the prevention of bacterial infections and cancer metastases

Adhesion of bacteria and of metastasizing tumour cells have much in common, especially the participation of lectins in this process. In the future it might be possible to inhibit the metastatic process and bacterial adhesion by blocking with lectins specific for appropriate (oligo) saccharides or glycoconjugates. Initial clinical trials are very promising.

Combined immunomodulation (Propionibacterium avidum KP-40) and lectin blocking (D-galactose) prevents liver tumor colonization in BALB/c-mice

The protective effect of combined treatment (immunomodulation with Propionibacterium avidum KP-40; liver lectin blocking by D-galactose administration) on the liver colonization of RAW 117-H10 lymphosarcoma was investigated in BALB/c-mice. Both, immunomodulation with P. avidum KP-40 as well as liver lectin blocking by D-galactose treatment significantly decreased the number of liver tumor colonies in this experimental model. However, the combination of P. avidum KP-40 and D-galactose obviously proved to be superior to each monotherapy since the liver colonization by RAW 117-H 10 lymphosarcoma could be completely inhibited.

Hepatocellular injury inhibits lectin-mediated tumor colonization into BALB/c-mice livers

Acute (hepatitis) and chronic (cirrhosis) liver injuries were experimentally induced in BALB/c-mice by administration of D-galactosamine and carbon tetrachloride, respectively. In both experimental liver diseases the incidence of hepatic tumor colonization of sarcoma L-1 was significantly reduced as compared to non-treated control animals. Thus, it seems that either dysfunction or loss of organ-characteristic lectins (galactosyl-specific hepatic lectins) prevented liver colonization. Histochemical staining of liver sections from D-galactosamine or carbon tetrachloride-treated mice with appropriate galactose-containing (neo)glycoproteins supported this hypothesis, since the lectin-dependent binding was greatly reduced as compared to sections from non-treated animals.

Rapid analysis of leukocyte-endothelial adhesion

Neutrophil adherence to endothelial monolayers in multi-well plates can be rapidly quantitated, using a fluorescent plate reader. The number of adherent neutrophils which have been labeled with biscarboxyethyl carboxyfluorescein (BCECF) was calculated by comparing fluorescence of endothelial monolayers to a reference standard curve determined by fluorescence intensity of suspensions of labeled neutrophils. The limit of sensitivity approached 100 cells, which is similar to that achieved by the most sensitive of alternate techniques. The assay, after isolation of the neutrophils, can be completed in 1.5 h. The ability to utilize microwell plates permits the use of large numbers of samples. This method has the advantage of being relatively simple and rapid while maintaining a sensitivity comparable to alternate approaches which employ radioactive labeling or counting of adherent or non-adherent cells.

Propionibacterium acnes-metabolites inhibit experimental lung metastasis of murine sarcoma L-1 in BALB/c-mice

Adhesive interactions between tumor cells and host tissue occur at several stages of metastasis. Such interactions might be inhibited by microbial metabolites resembling the binding regions of matrix molecules. Certain metabolite sequences including Gly, Asp, Arg, and Ser (GAAS) proved to be critical for cell interactions, e.g. with fibronectin. In vitro, the rosette formation of murine pulmonary cells and sarcoma L-1 cells decreased significantly in the presence of Propionibacterium acnes-metabolites rich in GAAS. In vivo, coinjection of Propionibacterium acnes-metabolites and sarcoma L-1 cells significantly inhibited the formation of lung colonies in BALB/c mice. The inhibition of lung colonization by these metabolites appeared to be noncytotoxic and obviously did not result from impairment of cellular tumorigenicity.

Purification and properties of a fucoidan-binding protein from human placenta and its identification as immunoglobulin G

1. A fucoidan-binding protein from human placenta was purified by affinity chromatography on immobilized fucoidan. 2. Characterization of molecular and immunological properties and peptide mapping indicated that the fucoidan-binding protein is an immunoglobulin G. 3. Cleavage with papain and transblot analysis with labelled fucoidan ascertained binding properties of the F(ab) fragments. 4. The specificity for fucoidan was furthermore substantiated by hapten inhibition of haemagglutination as well as by solid-phase assays with biotinylated fucoidan as ligand. The results emphasized the importance of structural features instead of simple ionic interactions. 5. Chemical modification with group-specific reagents to lysine, arginine, tryptophan, tyrosine and histidine resulted in substantial inactivation, their impact being markedly reduced by the presence of fucoidan in the cases of lysine, arginine and tryptophan.

Simple colorimetric cell-cell adhesion assay using biotinylated lymphocytes

A new approach for quantitating lymphocyte adhesion based on labeling the lymphocyte plasma membrane with water-soluble biotin was developed. Adherent biotinylated lymphocytes were quantitated by measuring OD values of a colored substrate representing the amount of bound avidin-peroxidase. The lymphocyte adhesion assay based on the high affinity of avidin to biotin was considerably more sensitive when compared to rose bengal or [3H]thymidine labeling methods. The end-point of sensitivity is approximately 1000 lymphocytes which is clearly an improvement over the rose bengal or radiolabeling techniques with a detection limit of respectively 15 x 10(3) and 7.5 x 10(3) lymphocytes added to wells at the beginning of the assay. The method has the advantage of being rapid and simple and offers an alternative to adhesion assays based on cell ELISAs using cell-specific monoclonal antibodies.

Lectins: mediators of adhesion for bacteria in infectious diseases and for tumor cells in metastasis

Adhesion of bacteria and adhesion of tumor cells have much in common, especially the participation of lectins in this process. In the future it might be possible to inhibit the metastatic process into the liver (e.g. during surgical operations of malignant tumors) and bacterial adherence to mucosal linings or plastic devices by blocking of adhesion molecules (lectins) with appropriate glycoconjugates. Initial clinical trials are very promising.