The potential of liposomes with carbonic anhydrase IX to deliver anticancer ingredients to cancer cells in vivo

The Chemical Reactivity of Membrane Lipids

It is well-known that aqueous dispersions of phospholipids spontaneously assemble into bilayer structures. These structures have numerous applications across chemistry and materials science and form the fundamental structural unit of the biological membrane. The particular environment of the lipid bilayer, with a water-poor low dielectric core surrounded by a more polar and better hydrated interfacial region, gives the membrane particular biophysical and physicochemical properties and presents a unique environment for chemical reactions to occur. Many different types of molecule spanning a range of sizes, from dissolved gases through small organics to proteins, are able to interact with membranes and promote chemical changes to lipids that subsequently affect the physicochemical properties of the bilayer. This Review describes the chemical reactivity exhibited by lipids in their membrane form, with an emphasis on conditions where the lipids are well hydrated in the form of bilayers. Key topics include the following: lytic reactions of glyceryl esters, including hydrolysis, aminolysis, and transesterification; oxidation reactions of alkenes in unsaturated fatty acids and sterols, including autoxidation and oxidation by singlet oxygen; reactivity of headgroups, particularly with reactive carbonyl species; and E/Z isomerization of alkenes. The consequences of reactivity for biological activity and biophysical properties are also discussed.

Nanomedicine for renal cell carcinoma: imaging, treatment and beyond

The kidney is a vital organ responsible for maintaining homeostasis in the human body. However, renal cell carcinoma (RCC) is a common malignancy of the urinary system and represents a serious threat to human health. Although the overall survival of RCC has improved substantially with the development of cancer diagnosis and management, there are various reasons for treatment failure. Firstly, without any readily available biomarkers, timely diagnosis has been greatly hampered. Secondly, the imaging appearance also varies greatly, and its early detection often remains difficult. Thirdly, chemotherapy has been validated as unavailable for treating renal cancer in the clinic due to its intrinsic drug resistance. Concomitant with the progress of nanotechnological methods in pharmaceuticals, the management of kidney cancer has undergone a transformation in the recent decade. Nanotechnology has shown many advantages over widely used traditional methods, leading to broad biomedical applications ranging from drug delivery, prevention, diagnosis to treatment. This review focuses on nanotechnologies in RCC management and further discusses their biomedical translation with the aim of identifying the most promising nanomedicines for clinical needs. As our understanding of nanotechnologies continues to grow, more opportunities to improve the management of renal cancer are expected to emerge.

Targeting carbonic anhydrase IX and XII isoforms with small molecule inhibitors and monoclonal antibodies

Carbonic anhydrases IX and CAXII (CAIX/CAXII) are transmembrane zinc metalloproteins that catalyze a very basic but crucial physiological reaction: the conversion of carbon dioxide into bicarbonate with a release of the proton. CA, especially CAIX and CAXII isoforms gained the attention of many researchers interested in anticancer drug design due to pivotal functions of enzymes in the cancer cell metastasis and response to hypoxia, and their expression restricted to malignant cells. This offers an opportunity to develop new targeted therapies with fewer side effects. Continuous efforts led to the discovery of a series of diverse compounds with the most abundant sulphonamide derivatives. Here we review current knowledge considering small molecule and antibody-based targeting of CAIX/CAXII in cancer.

Carbonic Anhydrase-IX Guided Albumin Nanoparticles for Hypoxia-mediated Triple-Negative Breast Cancer Cell Killing and Imaging of Patient-derived Tumor

Triple-Negative Breast Cancer (TNBC) is considered as the most onerous cancer subtype, lacking the estrogen, progesterone, and HER2 receptors. Evaluating new markers is an unmet need for improving targeted therapy against TNBC. TNBC depends on several factors, including hypoxia development, which contributes to therapy resistance, immune evasion, and tumor stroma formation. In this study, we studied the curcumin analogue (3,4-Difluorobenzylidene Curcumin; CDF) encapsulated bovine serum albumin (BSA) nanoparticle for tumor targeting. For tumor targeting, we conjugated Acetazolamide (ATZ) with CDF and encapsulated it in the BSA to form a nanoparticle (namely BSA-CDF-ATZ). The in vitro cytotoxicity study suggested that BSA-CDF-ATZ is more efficient when compared to free CDF. The BSA-CDF-ATZ nanoparticles showed significantly higher cell killing in hypoxic conditions compared to normoxic conditions, suggesting better internalization of the nanoparticles into cancer cells under hypoxia. Fluorescent-dye labeled BSA-CDF-ATZ revealed higher cell uptake of the nanoparticle compared to free dye indicative of better delivery, substantiated by a high rate of apoptosis-mediated cell death compared to free CDF. The significantly higher tumor accumulation and low liver and spleen uptake in TNBC patient-derived tumor xenograft models confirm the significant potential of BSA-CDF-ATZ for targeted TNBC imaging and therapy.

Dual-Functional Liposomes with Carbonic Anhydrase IX Antibody and BR2 Peptide Modification Effectively Improve Intracellular Delivery of Cantharidin to Treat Orthotopic Hepatocellular Carcinoma Mice

Liposomal nanotechnology has a great potential to overcome the current major problems of chemotherapy. However, the lack of penetrability and targetability retards the successful delivery of liposomal carriers. Previously, we showed that BR2 peptide modification endowed cantharidin-loaded liposomes with intracellular penetration that enhanced the drug cytotoxic effects. Here, we aimed to improve the targeting delivery of drugs into cancer cells via highly expressed carbonic anhydrase IX (CA IX) receptors by modifying our previous catharidin-loaded BR2-liposomes with anti-CA IX antibody. A higher cellular uptake of dual-functional liposomes (DF-Lp) than other treatments was observed. Induction of CA IX over-expressing resulted in a higher cellular binding of DF-Lp; subsequently, blocking with excess antibodies resulted in a decreased cancer-cell association, indicating a specific targeting property of our liposomes towards CA IX expressed cells. After 3h tracking, most of the liposomes were located around the nucleus which confirmed the involvement of targeting intracellular delivery. Cantharidin loaded DF-Lp exhibited enhanced cytotoxicity in vitro and was most effective in controlling tumor growth in vivo in an orthotopic hepatocellular carcinoma model compared to other groups. Collectively, our results presented the advantage of the BR2 peptide and CA IX antibody combination to elevate the therapeutic potential of cantharidin loaded DF-liposomes.

Computational modeling of novel inhibitory peptides targeting proteoglycan like region of carbonic anhydrase IX and in vitro validation in HeLa cells

Carbonic anhydrase IX (CAIX) is a tumour-associated, hypoxia-induced, membrane-bound metallo-enzyme which catalyzes the reversible hydration of carbon dioxide (CO₂) to bicarbonate (HCO₃^-) and proton (H⁺) ions. Over expression of CAIX is observed in cancers of colon, lung, kidney, breast, etc. CAIX plays a vital role in maintaining favourable intracellular pH for tumour cell growth and extracellular acidification which in-turn leads to drug resistance and spread of factors influencing tumour invasion. The N-terminal proteoglycan (PG) - like fragment of CAIX is unique to this isoform and is considered as potential druggable hotspot. Recently, M75 monoclonal antibody targeting the LPGEEDLPG epitope of PG like region has been proposed to reduce cellular adhesion in cancer cells. LPGEEDLPG fragment in complex with M75 has been crystallized and it serves as a strong base for development of peptide inhibitors based on interacting interfaces. Thus, in this study, an in-depth analysis of intermolecular interactions in LPGEEDLPG-M75 complex was carried out by implementing extensive molecular dynamics simulations, binding free energy calculations so as to infer the major determinant fragments of M75 that can be used as peptide inhibitors targeting PG region. Based on these analyses, 3 peptides (Pep1, Pep2 and Pep3) were synthesized and validated by in vitro assays involving cytotoxicity assessment, CAIX inhibition analysis through Direct and Indirect functional assays, and inhibition of Cell adhesion in HeLa cells. The results reveal Pep1 to be a promising inhibitor as it could efficiently modulate CAIX mediated pH homeostasis and cell adhesion in cancer cells.Communicated by Ramaswamy H. Sarma.

Surface Functionalization and Targeting Strategies of Liposomes in Solid Tumor Therapy: A Review

Surface functionalization of liposomes can play a key role in overcoming the current limitations of nanocarriers to treat solid tumors, i.e., biological barriers and physiological factors. The phospholipid vesicles (liposomes) containing anticancer agents produce fewer side effects than non-liposomal anticancer formulations, and can effectively target the solid tumors. This article reviews information about the strategies for targeting of liposomes to solid tumors along with the possible targets in cancer cells, i.e., extracellular and intracellular targets and targets in tumor microenvironment or vasculature. Targeting ligands for functionalization of liposomes with relevant surface engineering techniques have been described. Stimuli strategies for enhanced delivery of anticancer agents at requisite location using stimuli-responsive functionalized liposomes have been discussed. Recent approaches for enhanced delivery of anticancer agents at tumor site with relevant surface functionalization techniques have been reviewed. Finally, current challenges of functionalized liposomes and future perspective of smart functionalized liposomes have been discussed.

Construction of ultrasonic nanobubbles carrying CAIX polypeptides to target carcinoma cells derived from various organs

Background

Ultrasound molecular imaging is a novel diagnostic approach for tumors, whose key link is the construction of targeted ultrasound contrast agents. However, available targeted ultrasound contrast agents for molecular imaging of tumors are only achieving imaging in blood pool or one type tumor. No targeted ultrasound contrast agents have realized targeted ultrasound molecular imaging of tumor parenchymal cells in a variety of solid tumors so far. Carbonic anhydrase IX (CAIX) is highly expressed on cell membranes of various malignant solid tumors, so it’s a good target for ultrasound molecular imaging. Here, targeted nanobubbles carrying CAIX polypeptides for targeted binding to a variety of malignant tumors were constructed, and targeted binding ability and ultrasound imaging effect in different types of tumors were evaluated.

Results

The mean diameter of lipid targeted nanobubbles was (503.7 ± 78.47) nm, and the polypeptides evenly distributed on the surfaces of targeted nanobubbles, which possessed the advantages of homogenous particle size, high stability, and good safety. Targeted nanobubbles could gather around CAIX-positive cells (786-O and Hela cells), while they cannot gather around CAIX-negative cells (BxPC-3 cells) in vitro, and the affinity of targeted nanobubbles to CAIX-positive cells were significantly higher than that to CAIX-negative cells (P < 0.05). Peak intensity and duration time of targeted nanobubbles and blank nanobubbles were different in CAIX-positive transplanted tumor tissues in vivo (P < 0.05). Moreover, targeted nanobubbles in CAIX-positive transplanted tumor tissues produced higher peak intensity and longer duration time than those in CAIX-negative transplanted tumor tissues (P < 0.05). Finally, immunofluorescence not only confirmed targeted nanobubbles could pass through blood vessels to enter in tumor tissue spaces, but also clarified imaging differences of targeted nanobubbles in different types of transplanted tumor tissues.

Conclusions

Targeted nanobubbles carrying CAIX polypeptides can specifically enhance ultrasound imaging in CAIX-positive transplanted tumor tissues and could potentially be used in early diagnosis of a variety of solid tumors derived from various organs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-017-0307-0) contains supplementary material, which is available to authorized users.

Drug delivery system targeting advanced hepatocellular carcinoma: Current and future

Hepatocellular carcinoma (HCC) has a fairly high morbidity and is notoriously difficult to treat due to long latent period before detection, multidrug resistance and severe drug-related adverse effects from chemotherapy. Targeted drug delivery systems (DDS) that can selectively deliver therapeutic drugs into tumor sites have demonstrated a great potential in cancer treatment, which could be utilized to resolve the limitations of conventional chemotherapy. Numerous preclinical studies of DDS have been published, but targeted DDS for HCC has yet to be made for practical clinical use. Since rational targeted DDS design should take cancer-specific properties into consideration, we have reviewed the biological and physicochemical properties of HCC extensively to provide a comprehensive understanding on HCC, and recent DDS studies on HCC, aiming to find some potential targeted DDSs for HCC treatment and a meaningful platform for further development of HCC treatments.

FROM THE CLINICAL EDITOR

Hepatocellular carcinoma has a high incidence worldwide and is known to be multidrug resistant. Thus, intensive research is being carried out to find better chemotherapeutic agents as well as new drug delivery systems. In this article, the authors reviewed in depth the current challenges facing new drug designs and also outlined novel targeted drug delivery systems (DDS) in the fight against HCC.

Multi-liposomal containers

Small unilamellar liposomes, 40-60 nm in diameter, composed of anionic diphosphatidylglycerol (cardiolipin, CL(2-)) or phosphatidylcerine (PS(1-)) and zwitter-ionic egg yolk lecithin (EL) or dipalmitoylphosphatidylcholine (DPPC), electrostatically complex with polystyrene microspheres, ca. 100 nm in diameter, grafted by polycationic chains ("spherical polycationic brushes", SPBs). Polymer/liposome binding studies were carried out using electrophoretic mobility (EPM), dynamic light scattering (DLS), fluorescence, conductometry, differential scanning calorimetry (DSC), and cryogenic transmission electron microscopy (cryo-TEM) as the main analytical tools. By these means a remarkably detailed picture emerges of molecular events inside a membrane. The following are among the most important conclusions that arose from the experiments: (a) binding of liposomes to SPBs is accompanied by flip-flop of anionic lipids from the inner to the outer leaflet of the liposomal membrane along with lateral lipid segregation into "islands". (b) The SPB-induced structural reorganization of the liposomal membrane, together with the geometry of anionic lipid molecules, determines the maximum molar fraction of anionic lipid (a key parameter designated as ν) that ensures the structural integrity of liposomes upon complexation: ν=0.3 for liposomes with conically-shaped CL(2-) and ν=0.5 for liposomes with anionic cylindrically-shaped PS(1-). (c) The number of intact liposomes per SPB particle varies from 40 for (ν=0.1) to 13 (ν=0.5). (d) By using a mixture of liposomes with variety of encapsulated substances, multi-liposomal complexes can be prepared with a high loading capacity and a controlled ratio of the contents. (e) In order to make the mixed anionic liposomes pH-sensitive, they are additionally modified by 30 mol% of a morpholinocyclohexanol-based lipid that undergoes a conformational flip when changing pH. Being complexed with SPBs, such liposomes rapidly release their contents when the pH is reduced from 7.0 to 5.0. The results allow loaded liposomes to be concentrated within a rather small volume and, thereby, the preparation of multi-liposomal containers of promise in the drug delivery field.

Exploring Different Strategies for Efficient Delivery of Colorectal Cancer Therapy

Colorectal cancer (CRC) is the third most common cancer and the fourth leading cause of cancer death in the world. Currently available chemotherapy of CRC usually delivers the drug to both normal as well as cancerous tissues, thus leading to numerous undesirable effects. Much emphasis is being laid on the development of effective drug delivery systems for achieving selective delivery of the active moiety at the anticipated site of action with minimized unwanted side effects. Researchers have employed various techniques (dependent on pH, time, pressure and/or bacteria) for targeting drugs directly to the colonic region. On the other hand, systemic drug delivery strategies to specific molecular targets (such as FGFR, EGFR, CD44, EpCAM, CA IX, PPARγ and COX-2) overexpressed by cancerous cells have also been shown to be effective. This review aims to put forth an overview of drug delivery technologies that have been, and may be developed, for the treatment of CRC.

Pirfenidone-loaded liposomes for lung targeting: preparation and in vitro/in vivo evaluation

BACKGROUND

The purpose of this study was to develop novel pirfenidone (PFD)-loaded liposomes for targeting to the lung.

METHODS

The liposomes were prepared by the film hydration method, and their in vitro/vivo characteristics were evaluated.

RESULTS

The PFD liposomes appeared visually as green to yellowish suspensions and were spherical in shape. The particle size was 582.3±21.6 nm and the entrapment efficiency was relatively high (87.2%±5.7%). The liposomes showed typical sustained and prolonged drug-release behavior in vitro and fitted well with the Weibull distribution equation. The relatively slower time taken to reach a minimal plasma PFD concentration in vivo suggests that PFD liposomes have a sustained-release profile, which is consistent with the results of the in vitro release study. The PFD liposomes showed the largest area under the curve for the lung. The high distribution of PFD achieved in the lungs using this liposomal formulation may be explained by physical entrapment of the liposomes in the vascular network of the lung. Histopathological results indicated that liposomal PFD could alleviate pathological injury in lung tissue.

CONCLUSION

This liposomal formulation can enable sustained release of PFD and increase targeting to the lung.