Pharmacological evaluation of imidazole-derived bisphosphonates on receptor activator of nuclear factor-κB ligand-induced osteoclast differentiation and function

Bisphosphonates (BPs) have been commonly used in the treatment of osteolytic bone lesions, such as osteoporosis and osteogenesis imperfecta. However, serious side-effects can occur during the therapy. To search for novel potent BPs with lower side-effects, a series of imidazole-containing BPs (zoledronic acid [ZOL]; ZOL derivatives by substitution of the hydrogen at the 2-position on the imidazole ring with a methyl [MIDP], ethyl [EIDP], n-propyl [PIDP], or n-butyl group [BIDP]) were developed and the effects on receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation were investigated using the murine macrophage RAW 264.7 cells at the protein, gene, and morphological and functional levels. Influences of these BPs on the cell growth and proliferation of RAW 264.7 were also studied in order to determine cytotoxicity. The results showed that PIDP significantly inhibited the RANKL-induced osteoclast formation in a dose-dependent fashion without inducing cytotoxicity under the concentration of 12.5 μM. It exerted remarkable suppressive effects on the development of actin rings, the bone resorption, and the expressions of osteoclastogenesis-related gene and protein markers. The down-regulation of c-Jun N-terminal kinase (JNK), protein kinase B (Akt), and inhibitor of nuclear factor kappa-B (IκB) phosphorylation in the early signaling event and subsequent inhibition of the expression of c-Fos and nuclear factor of activated T cells (NFATc1) might be involved in these effects. All these results indicated that PIDP might be a promising drug to treat bone-related disorders.

Density functional theory studies on a non-covalent interaction system: hydrogen-bonded dimers of zoledronate

A computational study was carried out to characterize the hydrogen-bonded dimers of Zoledronate (ZOL), which is used widely in treating skeletal diseases. The stable conformations, hydrogen bonding interactions, IR spectra, thermodynamic properties, and electronic characteristics of nine possible ZOL dimers were studied using density functional theory (DFT) at the B3LYP/6-311++G** level. The stability of dimers was determined according to the analyses of total electronic energies and hydrogen bonding interactions. The results showed that both the number and intensity of hydrogen bonds played an important role in determining the stability order of dimers, and the hydrogen bonding interactions in dimers resulted in a red shift of hydroxyl vibration with a corresponding increase in intensity. The calculated thermodynamic properties illustrated that the dimerization process can take place spontaneously at room temperature. Natural bond orbital and atoms in molecules analyses revealed that the nature of hydrogen bonding interactions was attributed to the interactions from lone pair orbital n(A) to the antibonding orbital σ*(D-H), and the interactions were closed-shell interactions in hydrogen-bonded dimers of ZOL. Graphical abstract Changes in Gibbs free energy and infrared spectra of ZL in the dimerization process.

M4IDP, a zoledronic acid derivative, induces G1 arrest, apoptosis and autophagy in HCT116 colon carcinoma cells via blocking PI3K/Akt/mTOR pathway

AIMS

The aim of this work was to examine the antitumor effects and mechanisms of M₄IDP, a zoledronic acid derivative, on human colorectal cancer (CRC) HCT116 cells.

MAIN METHODS

The effects of M₄IDP on proliferation, cell cycle and ROS production were determined by CCK-8 and flow cytometry assays. Annexin-V-FITC/PI, Hoechst 33258, MDC staining assays and Ad-mCherry-GFP-LC3B fluorescence assay were performed to investigate apoptosis and autophagy. The effects of M₄IDP on the induction of ER stress as well as the expression of cell cycle, apoptosis and autophagy-related proteins were analyzed by western blot assay.

KEY FINDINGS

M₄IDP exhibited strong and sustained inhibitory effect on the growth of HCT116 cells. G1 arrest caused by M₄IDP might be attributed to the enhancement of p27 and reduction of cyclin D1 expression. Proper-time treatment of M₄IDP activated autophagy and promoted autophagic flux, while long-time treatment might inhibit the autophagic degradation and undermine the autophagy. M₄IDP-induced apoptosis and autophagy were related to the ROS production and subsequent ER stress. M₄IDP treatment increased the expression of PTEN, inhibited the phosphorylation of PDK1, Akt, mTOR, p70S6K, and increased the phosphorylation of GSK-3β and Bad, suggesting that the inhibition of PI3K/Akt/mTOR pathway might be involved in the antitumor activities of M₄IDP.

SIGNIFICANCE

Our study indicates the antitumor properties of M₄IDP and its potential clinical use in CRC therapy by blocking PI3K/Akt/mTOR pathway. This study also provides a better understanding of the antitumor effects and the underlying mechanisms of bisphosphonates in the field of CRC therapy.

Recurrent supramolecular scenarios within complex 3-D hydrogen bond networks derived from organic ammonium salts of (4-amino-1-hydroxybutylidine)-1,1-bisphosphonic acid

Reactions of (4-amino-1-hydroxybutylidine)-1,1-bisphosphonic acid (LH₅) with organic amines or diamines in aqueous solution yields crystalline compounds of the general formula [(RN)H]₂[LH₃] or [(R'N)H₂][LH₃].

Synthesis, crystal structure and antitumor effect of a novel copper(II) complex bearing zoledronic acid derivative

A great majority of Cu(II) complexes currently studied in the anticancer research field exert their antiproliferative activities through ligand exchange. In this work, we present the synthesis and structural characterization of two novel Cu(II) complexes, {[Cu3(ZL)2(H2O)6]·6H2O}n (1) (ZL = 1-hydroxy-2-(1H-imidazol-1-yl)ethane-1,1-diyldiphosphonic acid) and [Cu(IPrDP)2]·3H2O (2) (IPrDP = 1-hydroxy-3-(1H-imidazol-1-yl)propane-1,1-diyldiphosphonic acid). Due to the insolubility of polymer 1 in common solvents, only the biological activities of complex 2 were investigated. The antitumor activity of complex 2 was evaluated against a panel of human cancer cell lines, including U2OS, A549, HCT116, MDA-MB-231 and HepG2. Complex 2 exhibited comparable cytotoxic effect to cisplatin (CDDP) against the human colon carcinoma cells HCT116, and superior selectivity for inhibiting human hepatocarcinoma cells rather than normal liver cells. The cell cycle distribution analysis indicates that complex 2 inhibits human carcinoma cells by inducing the cell cycle arrest at the G2/M phase, showing a similar mechanism of action to that of CDDP. The binding interaction of complex 2 with calf thymus DNA (CT-DNA) has been explored by UV-vis absorption and circular dichroism (CD), demonstrating complex 2 has a moderate binding affinity for DNA through intercalation.