Bisphosphonamidate Clodronate Prodrug Exhibits Selective Cytotoxic Activity against Melanoma Cell Lines

Abstract

Bisphosphonates are used clinically to treat disorders of calcium metabolism and malignant bone disease and are known to inhibit cancer cell growth, adhesion, and invasion. However, clinical use of these agents for the treatment of extraskeletal disease is limited due to low cell permeability. We recently described a bisphosphonamidate prodrug strategy for efficient intracellular release of bisphosphonates, including clodronate (CLO), in NSCLC cells. To evaluate anticancer activity of this prodrug class across many cancer cell types, the bisphosphonamidate clodronate prodrug (CLO prodrug) was screened against the NCI-60 cell line panel, and was found to exhibit selectivity toward melanoma cell lines. Here, we confirm efficient cellular uptake and intracellular activation of this prodrug class in melanoma cells. We further demonstrate inhibition of melanoma cell proliferation, induction of apoptosis, and an anti-tumor effect of CLO prodrug in a xenograft model. These data suggest a novel therapeutic application for the CLO prodrug and potential to selectively target melanoma cells.

Synthesis and Immunomodulatory Activity of Fluorine‐Containing Bisphosphonates

“…This demonstrates the importance of the cell membrane permeability of BPs in determining their biological activity. Moreover, a bisphosphonamidate BP prodrug exhibits selectivity in tumor entry . Similar approaches have been used to develop new immunomodulatory prenyl pyrophosphates with increased cell entry and stability .…”

“…ChemMedChem 2019, 14,462 -468 www.chemmedchem.org sphosphonamidate BP prodrug exhibits selectivity in tumor entry. [38] Similar approaches have been used to develop new immunomodulatory prenyl pyrophosphates with increased cell entry and stability. [39][40][41] Ta ken together,t he development of BP prodrugs could open an ew avenuef or cancert herapy throughm ore efficient blocking of isoprenoid biosynthesis leadingt od ecreased tumor cell growth and the triggering of tumor immunity by Vg2Vd2Tcells.…”

Bisphosphonate-Generated ATP-Analogs Inhibit Cell Signaling Pathways

“…40 The anti-inflammatory activity of NNBPs is also of interest given their potent JAK2 and JAK3 inhibition, plus tiludronate has been shown to reduce cytokine production from activated macrophages, 35 to alleviate cachexia in nude mice xenograft models, 38 and is reported to be effective in treating erosive osteoarthritis of the hand 41 as well as knee osteoarthritis 39 effects that might all be improved with more active/bioavailable species. Plus, in the case of anticancer activity, kinases might also be targets for NNBP prepro-drugs 22–24 that form AppXp inhibitors. For example, we find that the activity of AppCCl 2 p against wild type EGFR is IC 50 ≈ 250 nM, but against five mutants, we find d746–750, 4.3 μ M; G719S, 760 nM; L858R, 490 nM; T790M, 270 nM; L858R, T790M, 80 nM, Table 3 and Figure S4.…”

“…We next sought to see how the clodronate-analog bisphosphonates and their preprodrug forms 27 – 33 (Figure S12) inhibited tumor cell growth, as well as how the corresponding AppXp analogues inhibited the ANT (as measured via mitochondrial respiration). The smaller bisphosphonates had very poor cell (H460) growth inhibition activity, with IC 50 values of ~500 μ M. This improved with the addition of an aromatic side-chain, the dibromobenzyl bisphosphonate having an IC 50 ≈ 26 μ M. However, major increases in activity were only found with the preprodrug species ( 27 – 33 ), as shown in Figure S12, with the pivaloyloxy-methylene (Piv) esters and the phosphoramidate analogs of clodronate 23,24 all having IC 50 values in the 0.4–6 μ M range. However, how do the protected NNBPs, that is, their AppXp products, actually kill cells?…”

Prodrugs of pyrophosphates and bisphosphonates: disguising phosphorus oxyanions

“…In later work compound 55b was also found to have a more potent effect on cell growth and viability in SK-Mel-5 and UACC-62 melanoma cell lines. 122 Moreover it was able to decrease tumour growth in a mouse xenograft model whereas no statistically significant effect was observed with equal doses of clodronate.…”