Polyvalent Dendrimer-Methotrexate as a Folate Receptor-Targeted Cancer Therapeutic

Abstract

Our previous studies have demonstrated that a generation 5 dendrimer (G5) conjugated with both folic acid (FA) and methotrexate (MTX) has a higher chemotherapeutic index than MTX alone. Despite this, batch-to-batch inconsistencies in the number of FA and MTX molecules linked to each dendrimer led to conjugate batches with varying biological activity, especially when scaleup synthesis was attempted. Since the MTX is conjugated through an ester linkage, there were concerns that biological inconsistency could also result from serum esterase activity and differential bioavailability of the targeted conjugate. In order to resolve these problems, we undertook a novel approach to synthesize a polyvalent G5–MTXn conjugate through click chemistry, attaching the MTX to the dendrimer through an esterase-stable amide linkage. Surface plasmon resonance binding studies show that a G5–MTX10 conjugate synthesized in this manner binds to the FA receptor (FR) through polyvalent interaction showing 4300-fold higher affinity than free MTX. The conjugate inhibits dihydrofolate reductase, and induces cytotoxicity in FR-expressing KB cells through FR-specific cellular internalization. Thus, the polyvalent MTX on the dendrimer serves the dual role as a targeting molecule as well as a chemotherapeutic drug. The newly synthesized G5–MTXn conjugate may serve as a FR-targeted chemotherapeutic with potential for cancer therapy.

The therapeutic effect of methotrexate-conjugated Pluronic-based polymeric micelles on the folate receptor-rich tumors treatment

“…Based on these results, it was suggested that although MTX has relatively lower affinity to folate receptor compared with FA (K D =~20-100 nM vs 31,32 MTX-conjugated micelles might bind to folate receptor through polyvalent interaction as reported recently. 21,33,34 cellular uptake mechanism of FITclabeled mixed micelles in KBv cells…”

Inclusion of a pH-responsive amino acid-based amphiphile in methotrexate-loaded chitosan nanoparticles as a delivery strategy in cancer therapy

“…Likewise, MTX does not exert its cytotoxic activity only towards neoplasic cells, but also targets other tissues, thus determining a range of side effects. Therefore, in order to overcome the undesirable toxicity of MTX and to circumvent the risks associated with the administration of the free drug, considerable research efforts have been directed toward novel nanotechnology-based MTX delivery approaches (Chen et al 2007;Kuznetsova et al 2012;Thomas et al 2012). Here, the enhanced cytotoxicity of MTX via the pH-responsive NPs means that a significant reverse effect of drug resistance could has occurred.…”

Bifunctional Phosphorus Dendrimers and Their Properties

“…This approach is paradoxical, as the synthesis of dendrimers aims at obtaining pure compounds, whereas the stochastic functionalization in the last step affords a mixture of compounds, which in particular can induce inconsistencies in biological responses [115].…”