Effect of various polyamino acids and D- and L-amino acids on the blood fibrinolytic system

Efficient Synthesis of Glutamate Peptide-Estradiol Conjugate for Imaging Estrogen Receptor-Positive Diseases

Molecular imaging of estrogen receptor-positive (ER+) pathway-activated system serves the basis of ER+ disease management such as cancers and endometriosis. ER+ patients have better response to endocrine therapy and survive twice as long as negative ER patients. However, tumor resistance resulting from clinical used aromatase inhibitors and antiestrogens is unpredictable. Radiolabeled ER+ ligand could quantify ER+ tissue uptake which helps to stage and restage of the cancer as well as endometriosis. The differential diagnosis of ER+ lesions by using a labeled ligand helps to select the patients for optimal response to endocrine therapy and to discontinue the treatment when resistance occurs. In addition, radiolabeled ER+ ligand serves as basis for image-guided response follow-up. Glutamate receptors are cell surface receptors which are overexpressed in inflammation and infection. Using glutamate peptide as a drug carrier helps to target intracellular genes via glutamate receptor-mediated process. Reports have shown that polyglutamate is a drug carrier that could alter drug solubility and enhance estrogen receptor-ligand binding pocket. However, polyglutamate was a blend of mixed polymer with a wide range of molecular weight. Thus, the structural confirmation and purity of the conjugates were not optimized. To overcome this problem, the efficient synthesis of glutamate peptide-estradiol (GAP-EDL) conjugate was achieved with high purity. EDL was conjugated site-specific at the first glutamate of GAP. The average cell uptake of ⁶⁸Ga-GAP-EDL was 5-fold higher than the previous reported synthesis. The efficient synthesis of GAP-EDL has greatly enhanced sensitivity and specificity in cell uptake studies. In vivo PET imaging studies indicated that ⁶⁸Ga-GAP-EDL could image ER (+) tumors in MCF-7 tumor-bearing mice. Therefore, GAP-EDL makes it possible to image ER-enriched endometriosis and cancer.

Renal targeting potential of a polymeric drug carrier, poly-l-glutamic acid, in normal and diabetic rats

BACKGROUND AND PURPOSE

Poly-l-glutamic acid (PG) has been used widely as a carrier to deliver anticancer chemotherapeutics. This study evaluates PG as a selective renal drug carrier.

EXPERIMENTAL APPROACH

3H-deoxycytidine-labeled PGs (17 or 41 kDa) and 3H-deoxycytidine were administered intravenously to normal rats and streptozotocin-induced diabetic rats. The biodistribution of these compounds was determined over 24 h. Accumulation of PG in normal kidneys was also tracked using 5-(aminoacetamido) fluorescein (fluoresceinyl glycine amide)-labeled PG (PG-AF). To evaluate the potential of PGs in ferrying renal protective anti-oxidative stress compounds, the model drug 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride (AEBSF) was conjugated to 41 kDa PG to form PG-AEBSF. PG-AEBSF was then characterized and evaluated for intracellular anti-oxidative stress efficacy (relative to free AEBSF).

RESULTS

In the normal rat kidneys, 17 kDa radiolabeled PG (PG-Tr) presents a 7-fold higher, while 41 kDa PG-Tr shows a 15-fold higher renal accumulation than the free radiolabel after 24 h post injection. The accumulation of PG-AF was primarily found in the renal tubular tissues at 2 and 6 h after an intravenous administration. In the diabetic (oxidative stress-induced) kidneys, 41 kDa PG-Tr showed the greatest renal accumulation of 8-fold higher than the free compound 24 h post dose. Meanwhile, the synthesized PG-AEBSF was found to inhibit intracellular nicotinamide adenine dinucleotide phosphate oxidase (a reactive oxygen species generator) at an efficiency that is comparable to that of free AEBSF. This indicates the preservation of the anti-oxidative stress properties of AEBSF in the conjugated state.

CONCLUSION/IMPLICATIONS

The favorable accumulation property of 41 kDa PG in normal and oxidative stress-induced kidneys, along with its capabilities in conserving the pharmacological properties of the conjugated renal protective drugs, supports its role as a potential renal targeting drug carrier.

Nanoparticle-mediated drug delivery for treating melanoma

Melanoma originated from melanocytes is the most aggressive type of skin cancer with limited treatment options. New targeted therapeutic options with the discovery of BRAF and MEK inhibitors have shown significant survival benefits. Despite the recent progress, development of chemoresistance and systemic toxicity remains a challenge for treating metastatic melanoma. While the response from the first line of treatment against melanoma using dacarbazine remains only 5-10%, the prolonged use of targeted therapy against mutated oncogene BRAF develops chemoresistance. In this review, we will discuss the nanoparticle-based strategies for encapsulation and conjugation of drugs to the polymer for maximizing their tumor distribution through enhanced permeability and retention effect. We will also highlight photodynamic therapy and design of melanoma-targeted nanoparticles.

In vivo magnetic resonance imaging of tumor protease activity

Increased expression of cathepsins has diagnostic as well as prognostic value in several types of cancer. Here, we demonstrate a novel magnetic resonance imaging (MRI) method, which uses poly-L-glutamate (PLG) as an MRI probe to map cathepsin expression in vivo, in a rat brain tumor model. This noninvasive, high-resolution and non-radioactive method exploits the differences in the CEST signals of PLG in the native form and cathepsin mediated cleaved form. The method was validated in phantoms with known physiological concentrations, in tumor cells and in an animal model of brain tumor along with immunohistochemical analysis. Potential applications in tumor diagnosis and evaluation of therapeutic response are outlined.

Lifestyle, fibrinolysis and lipids

Lifestyle including eating habits, physical training, smoking, drinking alcoholic beverages etc. can to a certain extent maintain or spoil our health. The physiological mechanisms of haemostasis and of lipoprotein metabolism play a role in acute cardiovascular diseases but also in a great number of chronic diseases in which vascular pathology is prominent. Imparied fibrinolysis and increased lipid levels are often incriminated in vascular disease. Lifestyle can modify fibrinolysis as well as lipid levels. Physical training, moderate eating habits, no smoking, moderate alcohol intake will be a beneficial influence on both fibrinolysis and lipid levels. The possibility that long-term pharmacological intervention may adversely affect fibrinolysis and lipid levels should always be considered.