Effect of Molecular Weight, Drug Load, and Charge of Gelatin-MTX Conjugates on Growth Inhibition of HL-60 Leukemia Cells

• Published in: Pharmaceutical research 2009-02, Vol.26 (2), p.338-345
• Main Authors: Chen, Chao-Sheng, Ofner, Clyde M. III
• Format: Article
• Language: English
• Subjects: Antimetabolites, Antineoplastic - chemistry; Antimetabolites, Antineoplastic - pharmacology; Biochemistry; Biological and medical sciences; Biomedical and Life Sciences; Biomedical Engineering and Bioengineering; Biomedicine; Carbodiimides - chemistry; Cell growth; Cell Proliferation - drug effects; charge; Chemistry, Pharmaceutical; Chemotherapy; Dose-Response Relationship, Drug; Drug Carriers; Drug Compounding; drug load; Ethylenediamines - chemistry; Gelatin - chemistry; General pharmacology; HL-60 Cells; HL-60 growth inhibition; Humans; Inhibitory Concentration 50; Isoelectric Focusing; Leukemia; Leukemia - pathology; macromolecular drug conjugates; Medical Law; Medical sciences; Methotrexate - chemistry; Methotrexate - pharmacology; Molecular Weight; Nephelometry and Turbidimetry; Pharmaceutical sciences; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Pharmacology/Toxicology; Pharmacy; Research Paper; Spectrophotometry, Ultraviolet; Surface Properties
• ISSN: 0724-8741; 1573-904X
• DOI: 10.1007/s11095-008-9746-5

Purpose Gelatin-methotrexate conjugates (G-MTX) with known molecular weight (MW), drug load, and charge were prepared and evaluated for growth inhibition on leukemia cells. Methods Gelatin (34 to 171 kDa) was reacted with a carbodiimide to prepare G-MTX with high (G-MTX-H) and low (G-MTX-L) drug loads. Cationic conjugates were prepared by ethylenediamine modification. MTX:gelatin molar ratios were determined spectrophotometricaly. Isoelectric focusing electrophoresis (IEF) and turbidity were used to measure isoelectric points (IEP). Growth inhibition profiles and IC₅₀ values were determined on HL-60 cells using a modified MTT assay. Results IC₅₀ values of anionic G-MTX-L (drug loads 0.5:1 to 2.2:1) increased linearly from 46 to 180 nM with MW. But, IC₅₀ values for anionic G-MTX-H (drug loads 7.4:1 to 25:1) showed little, if any, MW dependence and were about two times higher. IC₅₀ values for cationic G-MTX-L ranged from 770 to 2,900 nM and the relationship with MW was non-linear. Conclusions The growth inhibition ranking was MTX > anionic G-MTX-L > anionic G-MTX-H > cationic G-MTX-L. High drug load may hinder lysosomal enzyme degradation and drug release and contribute to suppression of the MW effect observed with G-MTX-L. A mechanism change is suggested as the cationic conjugates increase to the highest MW.