Bisphosphonate-induced ATP analog formation and its effect on inhibition of cancer cell growth

Abstract

Bisphosphonates (BPs) are effective inhibitors of tumor-induced bone resorption. Recent studies have demonstrated that BPs inhibit growth, attachment and invasion of cancer cells in culture and promote apoptosis. The mechanisms responsible for the observed anti-tumor effects of BPs are beginning to be elucidated. Recently, we reported that nitrogen-containing bisphosphonates (N-BPs) induce formation of a novel ATP analog (ApppI) as a consequence of the inhibition of farnesyl diphosphate synthase in the mevalonate pathway. Similar to AppCp-type metabolites of non-N-BPs, ApppI is able to induce apoptosis. This study investigated BP-induced ATP analog formation and its effect on cancer cell growth. To evaluate zoledronic acid (a N-BP)-induced ApppI accumulation, inhibition of protein prenylation and clodronate (a non-N-BP) metabolism to AppCCl2p, MCF-7 and MDA-MB-436 breast cancer cells, MCF-10A nonmalignant breast cells, PC-3 prostate cancer cells, MG-63 osteosarcoma cells, RPMI-8226, and NCI-H929 myeloma cells were treated with 25 micromol/l zoledronic acid or 500 micromol/l clodronate for 24 h. The inhibition of cell growth by zoledronic acid and clodronate was studied in MCF-7, MDA-MB-436, and RPMI-8226 cells by exposing the cells with 1-100 micromol/l zoledronic acid or 10-2000 micromol/l clodronate for 72 h. Marked differences in zoledronic acid-induced ApppI formation and clodronate metabolism between the cancer cell lines were observed. The production of cytotoxic ATP analogs in tumor cells after BP treatment is likely to depend on the activity of enzymes, such as farnesyl diphosphate synthase or aminoacyl-tRNA synthetases, responsible for ATP analog formation. Additionally, the potency of clodronate to inhibit cancer cell growth corresponds to ATP analog formation.

Mevalonate pathway intermediates downregulate zoledronic acid-induced isopentenyl pyrophosphate and ATP analog formation in human breast cancer cells

“…Similar to AppCCl 2 p (i.e., a metabolite of clodronate) [24], ApppI interferes with mitochondrial function and induces apoptosis in osteoclasts [17]. Moreover, we have demonstrated that the amount of IPP/ApppI correlates with ZOL-induced FPPS inhibition [17,18] and most importantly, cancer cell death in vitro [20]. Therefore, N-BPs evoke apoptosis by two mechanisms, indirectly via the inhibition of protein isoprenylation, and also directly via inhibition of mitochondrial adenine nucleotide translocase (ANT) by ATP analog, ApppI.…”

“…Disruption of the lipid modification of these proteins induces a series of changes leading to altered cell activity and indirect apoptosis, and has been suggested to underlie the cytotoxic effects of N-BPs. 6 However, in addition to the loss of prenylated proteins, inhibition of FPPS by NBPs in the MVP causes intracellular accumulation of isopentenyl pyrophosphate (IPP) and consequently induces the biosynthesis of a novel pro-apoptotic ATP analog ApppI (triphosphoric acid 1-adenosin-5'-yl ester 3-(3-methylbut-3-enyl) ester), in vitro [17][18][19][20] and in vivo [19,21]. Recently we observed that in addition to IPP/ApppI formation, NBPs induce isomeric dimethylallyl pyrophosphate (DMAPP) accumulation and consequent ApppD (triphosphoric acid 1-adenosin-5'-yl ester 3-(3-methylbut-2-enyl) ester) production [22].…”

“…Formation of ApppI from IPP is most probably catalyzed by the same metabolic pathway (i.e. aminoacyltRNA-synthetases) [23] as the nonhydrolyzable AppCp-type ATP analogs of nonnitrogen containing bisphosphonates (non-N-BPs), such as clodronate [18]. Similar to AppCCl 2 p (i.e., a metabolite of clodronate) [24], ApppI interferes with mitochondrial function and induces apoptosis in osteoclasts [17].…”

Adoptive Immunotherapy of Epithelial Ovarian Cancer with Vγ9Vδ2 T Cells, Potentiated by Liposomal Alendronic Acid

“…NBP drugs such as zoledronic acid (ZA) and alendronic acid (AA) inhibit FPP synthetase, thereby causing increased accumulation of PAgs (6). Consequently, ovarian and other transformed cells that take up these agents are killed more effectively by Vg9Vd2 T cells in vitro (7,8).…”

Purinergic signalling in the musculoskeletal system

“…The antitumour effects of these drugs are not clear but could involve apoptosis induced by the ATP analogue ApppI produced by nitrogen-containing bisphosphonates [453,454].…”