Intracellular delivery of cytochrome c by galactosylated albumin to hepatocarcinoma cells

Nano- and Micro-Platforms in Therapeutic Proteins Delivery for Cancer Therapy: Materials and Strategies

Proteins have emerged as promising therapeutics in oncology due to their great specificity. Many treatment strategies are developed based on protein biologics, such as immunotherapy, starvation therapy, and pro-apoptosis therapy, while some protein biologics have entered the clinics. However, clinical translation is severely impeded by instability, short circulation time, poor transmembrane transportation, and immunogenicity. Micro- and nano-particles-based drug delivery platforms are designed to solve those problems and enhance protein therapeutic efficacy. This review first summarizes the different types of therapeutic proteins in clinical and research stages, highlighting their administration limitations. Next, various types of micro- and nano-particles are described to demonstrate how they can overcome those limitations. The potential of micro- and nano-particles are then explored to enhance the therapeutic efficacy of proteins by combinational therapies. Finally, the challenges and future directions of protein biologics carriers are discussed for optimized protein delivery.

Cytochrome c in cancer therapy and prognosis

Cytochrome c (cyt c) is an electron transporter of the mitochondrial respiratory chain. Upon permeabilization of the mitochondrial outer membrane, cyt c is released into the cytoplasm, where it triggers the intrinsic pathway of apoptosis. Cytoplasmic cyt c can further reach the bloodstream. Apoptosis inhibition is one of the hallmarks of cancer and its induction in tumors is a widely used therapeutic approach. Apoptosis inhibition and induction correlate with decreased and increased serum levels of cyt c, respectively. The quantification of cyt c in the serum is useful in the monitoring of patient response to chemotherapy, with potential prognosis value. Several highly sensitive biosensors have been developed for the quantification of cyt c levels in human serum. Moreover, the delivery of exogenous cyt c to the cytoplasm of cancer cells is an effective approach for inducing their apoptosis. Similarly, several protein-based and nanoparticle-based systems have been developed for the therapeutic delivery of cyt c to cancer cells. As such, cyt c is a human protein with promising value in cancer prognosis and therapy. In addition, its thermal stability can be extended through PEGylation and ionic liquid storage. These processes could contribute to enhancing its therapeutic exploitation in clinical facilities with limited refrigeration conditions. Here, I discuss these research lines and how their timely conjunction can advance cancer therapy and prognosis.

Single-walled carbon nanotube conjugated cytochrome c as exogenous nano catalytic medicine to combat intracellular oxidative stress

Mitochondrial dysfunction has been reported to be one of the main causes of many diseases including cancer, type2 diabetes, neurodegenerative disorders, cardiac ischemia, sepsis, muscular dystrophy, etc. Under in vitro conditions, Cytochrome C (Cyt C) maintains mitochondrial homeostasis and stimulates apoptosis, along with being a key participant in the life-supporting function of ATP synthesis. Hence, the medicinal importance of Cyt C as catalytic defense is immensely important in various mitochondrial disorders. Here, we have developed a nanomaterial via electrostatically conjugating oxidized single-wall carbon nanotube with Cyt C (Cyt C@cSWCNT) for the exogenous delivery of Cyt C. The chemical and morphological characterization of the developed Cyt C@cSWCNT was done using UV-vis, FTIR, XPS, powder XRD, TGA/DSC, TEM, etc. The developed Cyt C@cSWCNT exhibited bifunctional catalase and peroxidase activity with K_m (∼ 642.7 μM and 351.6 μM) and V_max (∼0.33 μM/s and 2.62 μM/s) values, respectively. Also, through this conjugation Cyt C was found to retain its catalytic activity even at 60 °C, excellent catalytic recyclability (at least up to 3 times), and wider pH activity (pH = 3 to 9). Cyt C@cSWCNT was found to promote intracellular ROS quenching and maintain mitochondrial membrane potential and cellular membrane integrity via Na⁺/K⁺ ion homeostasis during the H₂O₂ stress. Overall the present strategy provides an alternative approach for the exogenous delivery of Cyt C which can be used as nano catalytic medicine.

Cytochrome c: Using Biological Insight toward Engineering an Optimized Anticancer Biodrug

The heme protein cytochrome c (Cyt c) plays pivotal roles in cellular life and death processes. In the respiratory chain of mitochondria, it serves as an electron transfer protein, contributing to the proliferation of healthy cells. In the cell cytoplasm, it activates intrinsic apoptosis to terminate damaged cells. Insight into these mechanisms and the associated physicochemical properties and biomolecular interactions of Cyt c informs on the anticancer therapeutic potential of the protein, especially in its ability to subvert the current limitations of small molecule-based chemotherapy. In this review, we explore the development of Cyt c as an anticancer drug by identifying cancer types that would be receptive to the cytotoxicity of the protein and factors that can be finetuned to enhance its apoptotic potency. To this end, some information is obtained by characterizing known drugs that operate, in part, by triggering Cyt c induced apoptosis. The application of different smart drug delivery systems is surveyed to highlight important features for maintaining Cyt c stability and activity and improving its specificity for cancer cells and high drug payload release while recognizing the continuing limitations. This work serves to elucidate on the optimization of the strategies to translate Cyt c to the clinical market.

Self-assembled guanosine-hydrogels for drug-delivery application: Structural and mechanical characterization, methylene blue loading and controlled release

It is known that guanosine derivatives (G) self-assemble in water forming long, flexible, and interacting aggregates (the so-called G-quadruplexes): by modulating the quadruplex charges, e.g. simply using a mixture of guanosine 5'-monophosphate (GMP) and guanosine (Gua), multi-responsive, self-healing hydrogels can be obtained. In this paper, the potential application of G-hydrogels as drug delivery systems has been assessed. Hydrogels were prepared at different Gua:GMP molar ratios. The photosensitizer Methylene Blue and the pro-apoptotic protein cytochrome C were used as cargo molecules. Small angle x-ray scattering and atomic force microscopy experiments confirmed the presence of G-quadruplexes disposed in swollen matrices with different mesh-sizes. Rheology measurements showed that the Gua:GMP molar ratio leads to specific drug release mechanisms, as the gel strength is finely tuned by electrostatic repulsion and van der Waals attraction between G-quadruplexes. Noteworthy, the gel cohesion and the drug release were pH responsive. Swelling, self-healing and cell viability features were also investigated: the results qualify the Gua:GMP hydrogel as an excellent biomaterial that can entrap and deliver key biomolecules in a sustained and responsive release manner.

A Cytochrome c-Chlorotoxin Hybrid Protein as a Possible Antiglioma Drug

Malignant gliomas are the most lethal form of primary brain tumors. Despite advances in cancer therapy, the prognosis of glioma patients has remained poor. Cytochrome c (Cytc), an endogenous heme-based protein, holds tremendous potential to treat gliomas because of its innate capacity to trigger apoptosis. To this end, a hybrid cytochrome c-chlorotoxin (Cytc-CTX) protein was biosynthesized to enable cellular uptake of the cell impenetrable Cytc using CTX transporters. A nucleotide sequence containing 1 : 1 Cytc and CTX was constructed and separated by a hexahistidine-tag and an enterokinase cleavage site. The sequence was cloned into a pBTR1 plasmid, expressed in Escherichia coli, purified via 2-dimensional chromatography. The identity and size of the protein were determined by Western blot and mass spectrometry. Cytc in this soluble hybrid protein has similar structure and stability as human Cytc and the hybrid protein is endocytosed into a glioma cell line, while displaying potent cytotoxicity and a favorable therapeutic index. Its facile, low-cost, and high yield synthesis, biocompatibility, and robustness suggest that the hybrid protein is a promising candidate for antiglioma drug evaluation.

Artificial Glycoproteins as a Scaffold for Targeted Drug Therapy

Akin to a cellular "fingerprint," the glycocalyx is a glycan-enriched cellular coating that plays a crucial role in mediating cell-to-cell interactions. To gain a better understanding of the factors that govern in vivo recognition, artificial glycoproteins were initially created to probe changes made to the accumulation and biodistribution of specific glycan assemblies through biomimicry. As a result, the organ-specific accumulation for a variety of glycoproteins decorated with simple and/or complex glycans was identified. Additionally, binding trends with regard to cancer cell selectivity were also investigated. To exploit the knowledge gained from these studies, numerous groups thus became engaged in developing targeted drug methodologies based on the use of artificial glycoproteins. This has either been done through adopting the glycoprotein scaffold as a drug carrier, or to directly glycosylate therapeutic proteins/enzymes to localize their biological activity. The principle aim of this Review is to present the foundational research that has driven artificial glycoprotein-based targeting and subsequent adaptations with potential therapeutic applications.

Ferritin nanovehicle for targeted delivery of cytochrome C to cancer cells

In this work, we have exploited the unique properties of a chimeric archaeal-human ferritin to encapsulate, deliver and release cytochrome c and induce apoptosis in a myeloid leukemia cell line. The chimeric protein combines the versatility in 24-meric assembly and cargo incorporation capability of Archaeglobus fulgidus ferritin with specific binding of human H ferritin to CD71, the "heavy duty" carrier responsible for transferrin-iron uptake. Delivery of ferritin-encapsulated cytochrome C to the Acute Promyelocytic Leukemia (APL) NB4 cell line, highly resistant to transfection by conventional methods, was successfully achieved in vitro. The effective liberation of cytochrome C within the cytosolic environment, demonstrated by double fluorescent labelling, induced apoptosis in the cancer cells.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2013-2014

This review is the eighth update of the original article published in 1999 on the application of Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2014. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly- saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 37:353-491, 2018.