Ibandronate increases the expression of the pro-apoptotic gene FAS by epigenetic mechanisms in tumor cells

Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Center Meidling, 1(st) Medical Department, Hanusch Hospital, Vienna, Austria.
Biochemical pharmacology (Impact Factor: 5.01). 10/2012; 85(2). DOI: 10.1016/j.bcp.2012.10.016
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There is growing evidence that aminobisphosphonates like ibandronate show anticancer activity by an unknown mechanism. Biochemically, they prevent posttranslational isoprenylation of small GTPases, thus inhibiting their activity. In tumor cells, activated RAS-GTPase, the founding member of the gene family, down-regulates the expression of the pro-apoptotic gene FAS via epigenetic DNA-methylation by DNMT1. We compared ibandronate treatment in neoplastic human U-2 osteosarcoma and in mouse CCL-51 breast cancer cells as well as in the immortalized non-neoplastic MC3T3-E1 osteoblastic cells. Ibandronate attenuated cell proliferation in all cell lines tested. In the neoplastic cells we found up-regulation of caspases suggesting apoptosis. Further we found stimulation of FAS-expression as a result of epigenetic DNA demethylation that was due to down-regulation of DNMT1, which was rescued by re-isoprenylation by both geranylgeranyl-pyrophosphate and farnesylpyrophosphate. By contrast, ibandronate did not affect FAS and DNMT1 expression in MC3T3-E1 non-neoplastic cells. Data suggest that bisphosphonates via modulation of the activity of small-GTPases induce apoptosis in neoplastic cells by DNA-CpG-demethylation and stimulation of FAS-expression. In conclusion the shown epigenetic mechanism underlying the anti-neoplastic activity of farnesyl-transferase-inhibition, also explains the clinical success of other drugs, which target this pathway.

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    • "Indeed, squalene synthase is not a possible target of ALN inhibition [37] and ALN is proposed to be a poor inhibitor in contrast to other N-BPs such as incadronate and ibandronate [38]. BPs are reported to act through changes in CpG-methylation state of gene promoter regions involved in the cell proliferation and apoptosis [39]. To examine the effect of ALN on promoter methylation, we examined gene expression of DNMT1, an enzyme responsible for CpG methylation during cell replication [40]. "
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    ABSTRACT: Cancer is a life threatening disorder effecting 11 million people worldwide annually. Among various types of cancers, Hepatocellular carcinoma (HCC) has a higher rate of mortality and is the fifth leading cause of cancer related deaths around the world. Many chemotherapeutic drugs have been used for the treatment of HCC with many side effects. These drugs are inhibitors of different cell regulatory pathways. Mevalonate (MVA) pathway is an important cellular cascade vital for cell growth. A variety of inhibitors of MVA pathway have been reported for their anticancerous activity. Bisphosphonates (BPs) are members of a family involved in the treatment of skeletal complications. In recent years, their anticancer potential has been highlighted. Current study focuses on exploring the effects of alendronate (ALN), a nitrogen containing BP, on hepatocellular carcinoma cell line using genomic and proteomics approach. Our results identified ten differentially expressed proteins, of which five were up regulated and five were down regulated in ALN treated cells. Furthermore, we also performed gene expression analysis in treated and control cell lines. The study may help in understanding the molecular mechanism involved in antitumor activity of ALN, identification of possible novel drug targets, and designing new therapeutic strategies for HCC.
    02/2014; 2014(6):532953. DOI:10.1155/2014/532953
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    • "A recent clinical study demonstrated that adjuvant therapy with the amino-BP zoledronic acid could improve the disease-free survival of women with early breast cancer without bone metastases7. The anti-tumor activity of ibandronate has been illustrated preclinically in many types of cancer, including breast8, lung9, multiple myeloma10 and osteosarcoma11. Overall, the positive effects of BPs and their clinical potential in cancer have been widely confirmed both in vitro and in vivo12,13. "
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    Acta Pharmacologica Sinica 11/2013; 34(12). DOI:10.1038/aps.2013.103 · 2.91 Impact Factor
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    • "However, as DAPK1 is involved in FAS-induced extrinsic apoptosis in lymphoid cells [88] and mediates the proapoptotic activity of TNF-␣ and INF-␥ (interferon-gamma) via the NF-␬B signaling pathways [89], there is no doubt considering a crucial contribution of this gene in the proapoptotic machinery as effected by demethylating drugs and histone-deacetylase inhibitors. In addition, FAS expression plays a critical role for AZA-induced and DAC-induced apoptosis as shown by siRNA experiments [90] and an increasing number of in vitro studies [22] [91]. In the present overview, we show that both FAS and DAPK1 are critical death regulators in neoplastic cells of MDS and AML. "
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    ABSTRACT: Disordered stem cell epigenetics and apoptosis-regulating mechanisms contribute essentially to the pathogenesis of myelodysplastic syndromes (MDS) and may trigger disease-progression to secondary acute myeloid leukemia (AML). Expression of apoptosis-mediators FAS (CD95) and DAPK1 the latter being also known for its association with autophagy are upregulated in neoplastic cells in patients with low-risk MDS and epigenetically silenced and downregulated in high-risk MDS and AML as confirmed by a study 50 MDS and 30 AMLs complementing this review. 5-Azacytidine (AZA) and 5-aza-2'deoxycytidine (DAC), promoted FAS and DAPK1 gene demethylation and their (re)expression as well as apoptosis in leukemic cell lines (HL-60, KG1) which can be reversed by siRNA against FAS. Thus, promoter-demethylation of FAS and DAPK1 represents a critical mechanism of drug-induced apoptosis in neoplastic cells in MDS and AML which underscores the clinical implication of epigenetically active therapies.
    Critical reviews in oncology/hematology 10/2013; 90(1). DOI:10.1016/j.critrevonc.2013.10.003 · 4.03 Impact Factor
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