Lectin-mediated cytotoxicity and specificity of 5-fluorouracil conjugated with peanut agglutinin (5-Fu-PNA)in vitro

Research advances and prospects of legume lectins

Lectins are widely distributed proteins having ability of binding selectively and reversibly with carbohydrates moieties and glycoconjugates. Although lectins have been reported from different biological sources, the legume lectins are the best-characterized family of plant lectins. Legume lectins are a large family of homologous proteins with considerable similarity in amino acid sequence and their tertiary structures. Despite having strong sequence conservation, these lectins show remarkable variability in carbohydrate specificity and quaternary structures. The ability of legume lectins in recognizing glycans and glycoconjugates on cells and other intracellular structures make them a valuable research tool in glycomic research. Due to variability in binding with glycans, glycoconjugates and multiple biological functions, legume lectins are the subject of intense research for their diverse application in different fields such as glycobiology, biomedical research and crop improvement. The present review specially focuses on structural and functional characteristics of legume lectins along with their potential areas of application.

Improved efficacy of doxorubicin delivery by a novel dual-ligand-modified liposome in hepatocellular carcinoma

Liposomes have been widely used as drug carriers in both biomedical research and for clinical applications, allowing the stabilisation of therapeutic compounds and overcoming obstacles to cellular and tissue uptake. However, liposomes still have low targeting efficiency, resulting in insufficient killing of tumour cells and unnecessary damage to normal cells. In this study, glycyrrhetinic acid (GA) and peanut agglutinin (PNA) were used as ligands to prepare dual-ligand-modified doxorubicin-loaded liposomes (DOX-GA/PNA-Lips) to enhance the targeting accuracy and efficacy of drug delivery against malignant liver cancer. PNA and GA modification enhanced the binding ability of liposomes to liver cancer cells, leading to excellent tissue and cell targeting of DOX-GA/PNA-Lips. DOX-GA/PNA-Lips showed an effective anti-tumour effect in vivo and in vitro, with its targeted delivery facilitating attenuation of the toxic side effects of DOX. These results demonstrated that dual-ligand-modified liposomes may provide an effective strategy for the treatment of hepatocellular carcinoma.

The antitumor activity of PNA modified vinblastine cationic liposomes on Lewis lung tumor cells: In vitro and in vivo evaluation

Non-small cell lung cancer (NSCLC) is one of the frequently-occurring disease in the world, and the treatment effects are usually unsatisfactory. Vinblastine is an anti-microtubule drug in clinic. In this study, a nanostructured liposome was designed and prepared for treating NSCLC. In the liposomes, peanut agglutinin (PNA) was modified on the liposomal surface, 3-(N-(N',N'-dimethylaminoethane)carbamoyl) cholesterol was used as cationic materials, and vinblastine was encapsulated in the aqueous core of liposomes, respectively. The PNA modified vinblastine cationic liposomes were approximately 100 nm in size with a positive potential. In vitro results showed that the targeting liposomes could significantly enhance cellular uptake, selectively accumulate in LLT cells, and dramatically initiate apoptosis via activating pro-apoptotic proteins and apoptotic enzymes, thus leading to the strongest antitumor efficacy to LLT cells. In vivo results demonstrated that the targeting liposomes could display a prolonged circulation time in the blood, accumulate more drug in tumor location, and induce most of tumor cells apoptosis. As a result, a robust overall antitumor efficacy in tumor-bearing mice was observed subsequently. In conclusion, the chemotherapy using the PNA modified vinblastine cationic liposomes could provide a potential strategy for treating non-small cell lung cancer.

Glycan-targeted drug delivery for intravesical therapy: in the footsteps of uropathogenic bacteria

The human urothelium belongs to the most efficient biobarriers, and represents a highly rewarding but challenging target for local drug administration. Inadequate urothelial bioavailability is a major obstacle for successful treatment of bladder cancer and other diseases, yet little research has addressed the development of advanced delivery concepts for the intravesical route. A prominent example of how to overcome the urothelial barrier by means of specific biorecognition is the efficient cytoinvasion of UPEC bacteria, mediated by the mannose-targeted lectin domain FimH. Similar mechanisms of non-bacterial origin may be exploited for enhancing drug uptake from the bladder cavity. This review covers the current status in the development of lectin-based delivery strategies for the urinary tract. Different concepts for preparing and optimizing carbohydrate-targeted delivery systems are presented, along with important design parameters, benefits and shortcomings. Bioconjugate- and nano-/microparticle-based systems are discussed in further detail with regard to their performance in preclinical testing.

Medicinal Applications of Plant Lectins

Plant lectins are a unique group of proteins and glycoproteins with potent biological activity and have received widespread attention for many years. They can be found in wheat, corn, tomatoes, peanuts, kidney beans, bananas, peas, lentils, soybeans, mushrooms, tubers, seeds, mistletoe and potatoes among many others. Due to their ability to bind reversibly with specific carbohydrate structures and their abundant availability, plant lectins have commonly been used as a molecular tool in various disciplines of biology and medicine. Whilst once thought of being a dietary toxin, the focus on plant lectins has since shifted to understanding the useful properties of these lectins and utilizing them in medicinal applications to advance human health. This chapter reviews the current and potential applications of plant lectins in various areas of medically related research.

Randomly 50%N-acetylated low molecular weight chitosan as a novel renal targeting carrier

Selective targeting of drugs to kidneys may improve renal effectiveness and reduce extrarenal toxicity. Using fluorescence imaging, we found for the first time that randomly 50% N-acetylated low molecular weight chitosan (LMWC) selectively accumulated in the kidneys, especially in the renal tubules after i.v. injection in mice. To develop and evaluate the novel renal drug carrier, prednisolone, used as a model drug, was covalently coupled with various molecular weight LMWCs via a succinic acid spacer. The mean residence time (MRT) in plasma of prednisolone conjugates increased as the molecular weight increased. The conjugate with molecular weight 19 kD (conjugate-19k) displayed the highest accumulation rate in the kidneys, which was 14.06+/-2.81% of the administered dose 15 min after i.v. injection. The total amount of the conjugate-19k in the kidneys was 13-fold higher than that of controlled prednisolone group. Both conjugate-19k and conjugate-31k had higher retention and about 10% of injected dose was still retained in the kidneys after 120 min. Additionally, MTT assay showed LMWCs were noncytotoxic towards L929 and NRK-52E cells. Conclusion can be drawn that the coupling of prednisolone to the proper molecular weight LMWC results in increased prednisolone concentration in the kidneys. Therefore, LMWC with a proper molecular weight can be applied as a promising carrier for renal targeting.

Lectin binding and effects in culture on human cancer and non-cancer cell lines: examination of issues of interest in drug design strategies

By using a non-cancer and a cancer cell line originally from the same tissue (colon), coupled with testing lectins for cell binding and for their effects on these cell lines in culture, this study describes a simple multi-parameter approach that has revealed some interesting results that could be useful in drug development strategies. Two human cell lines, CCL-220/Colo320DM (human colon cancer cells, tumorigenic in nude mice) and CRL-1459/CCD-18Co (non-malignant human colon cells) were tested for their ability to bind to agarose microbeads derivatized with two lectins, peanut agglutinin (Arachis hypogaea agglutinin, PNA) and Dolichos biflorus agglutinin (DBA), and the effects of these lectins were assessed in culture using the MTT assay. Both cell lines bound to DBA-derivatized microbeads, and binding was inhibited by N-acetyl-D-galactosamine, but not by L-fucose. Neither cell line bound to PNA-derivatized microbeads. Despite the lack of lectin binding using the rapid microbead method, PNA was mitogenic in culture at some time points and its mitogenic effect displayed a reverse-dose response. This was also seen with effects of DBA on cells in culture. While this is a simple study, the results were statistically highly significant and suggest that: (1) agents may not need to bind strongly to cells to exert biological effects, (2) cell line pairs derived from diseased and non-diseased tissue can provide useful comparative data on potential drug effects and (3) very low concentrations of potential drugs might be initially tested experimentally because reverse-dose responses should be considered.