New symmetrically esterified m-bromobenzyl non-aminobisphosphonates inhibited breast cancer growth and metastases

Synthesis and preliminary anticancer evaluation of photo-responsive prodrugs of hydroxymethylene bisphosphonate alendronate

The antitumoral activity of hydroxymethylene bisphosphonates (HMBP) such as alendronate or zoledronate is hampered by their exceptional bone-binding properties and their short plasmatic half-life which preclude their accumulation in non-skeletal tumors. In this context, the use of lipophilic prodrugs represents a simple and straightforward strategy to enhance the biodistribution of bisphosphonates in these tissues. We describe in this article the synthesis of light-responsive prodrugs of HMBP alendronate. These prodrugs include lipophilic photo-removable nitroveratryl groups which partially mask the highly polar alendronate HMBP scaffold. Photo-responsive prodrugs of alendronate are stable in physiological conditions and display reduced toxicity compared to alendronate against MDA-MB-231 cancer cells. However, the antiproliferative effect of these prodrugs is efficiently restored after cleavage of their nitroveratryl groups upon exposure to UV light. In addition, substitution of alendronate with such photo-responsive substituents drastically reduces its bone-binding properties, thereby potentially improving its biodistribution in soft tissues after i.v. administration. The development of such lipophilic photo-responsive prodrugs is a promising approach to fully exploit the anticancer effect of HMBPs on non-skeletal tumors.

Green Approach Toward Triazole Forming Reactions for Developing Anticancer Drugs

Compounds containing triazole have many significant applications in the dye and ink industry, corrosion inhibitors, polymers, and pharmaceutical industries. These compounds possess many antimicrobial, antioxidant, anticancer, antiviral, anti-HIV, antitubercular, and anticancer activities. Several synthetic methods have been reported for reducing time, minimizing synthetic steps, and utilizing less hazardous and toxic solvents and reagents to improve the yield of triazoles and their analogues synthesis. Among the improvement in methods, green approaches towards triazole forming biologically active compounds, especially anticancer compounds, would be very important for pharmaceutical industries as well as global research community. In this article, we have reviewed the last five years of green chemistry approaches on click reaction between alkyl azide and alkynes to install 1,2,3-triazole moiety in natural products and synthetic drug-like molecules, such as in colchicine, flavanone cardanol, bisphosphonates, thiabendazoles, piperazine, prostanoid, flavonoid, quinoxalines, C-azanucleoside, dibenzylamine, and aryl-azotriazole. The cytotoxicity of triazole hybrid analogues was evaluated against a panel of cancer cell lines, including multidrug-resistant cell lines.

Disintegrin-like Protein Strategy to Inhibit Aggressive Triple-Negative Breast Cancer

Venoms are a rich source of bioactive compounds, and among them is leberagin-C (Leb-C), a disintegrin-like protein derived from the venom of Macrovipera lebetina transmediterrannea snakes. Leb-C has shown promising inhibitory effects on platelet aggregation. Previous studies have demonstrated that this SECD protein specifically targets α5β1, αvβ3, and αvβ6 integrins through a mimic mechanism of RGD disintegrins. In our current study, we focused on exploring the potential effects of Leb-C on metastatic breast cancer. Our findings revealed that Leb-C disrupted the adhesion, migration, and invasion capabilities of MDA-MB-231 breast cancer cells and its highly metastatic D3H2LN sub-population. Additionally, we observed significant suppression of adhesion, migration, and invasion of human umbilical vein endothelial cells (HUVECs). Furthermore, Leb-C demonstrated a strong inhibitory effect on fibroblast-growth-factor-2-induced proliferation of HUVEC. We conducted in vivo experiments using nude mice and found that treatment with 2 µM of Leb-C resulted in a remarkable 73% reduction in D3H2LN xenograft tumor size. Additionally, quantification of intratumor microvessels revealed a 50% reduction in tumor angiogenesis in xenograft after 21 days of twice-weekly treatment with 2 µM of Leb-C. Collectively, these findings suggest the potential utility of this disintegrin-like protein for inhibiting aggressive and resistant metastatic breast cancer.

Prodrugs of pyrophosphates and bisphosphonates: disguising phosphorus oxyanions

Pyrophosphates have important functions in living systems and thus pyrophosphate-containing molecules and their more stable bisphosphonate analogues have the potential to be used as drugs for treating many diseases including cancer and viral infections. Both pyrophosphates and bisphosphonates are polyanionic at physiological pH and, whilst this is essential for their biological activity, it also limits their use as therapeutic agents. In particular, the high negative charge density of these compounds prohibits cell entry other than by endocytosis, prevents transcellular oral absorption and causes sequestration to bone. Therefore, prodrug strategies have been developed to temporarily disguise the charges of these compounds. This review examines the various systems that have been used to mask the phosphorus-containing moieties of pyrophosphates and bisphosphonates and also illustrates the utility of such prodrugs.

One-Pot Synthesis of Phosphinylphosphonate Derivatives and Their Anti-Tumor Evaluations

This paper reports on the synthesis of new hydroxymethylene-(phosphinyl)phosphonates (HMPPs). A methodology has been developed to propose an optimized one-pot procedure without any intermediate purifications. Various aliphatic and (hetero)aromatic HMPPs were synthesized in good to excellent yields (53–98%) and the influence of electron withdrawing/donating group substitution on aromatic substrates was studied. In addition, the one-pot synthesis of HMPP was monitored by ³¹P NMR spectroscopy, allowing effective control of the end of the reaction and identification of all phosphorylated intermediate species, which enabled us to propose a reaction mechanism. Optimized experimental conditions were applied to the preparation of biological relevant aminoalkyl-HMPPs. A preliminary study of the complexation to hydroxyapatite (bone matrix) was carried out in order to verify its lower affinity towards bone compared to bisphosphonate molecules. Moreover, in vitro anti-tumor activity study revealed encouraging antiproliferative activities on three human cancer cell lines (breast, pancreas and lung).

Synthesis and preliminary anticancer evaluation of new triazole bisphosphonate-based isoprenoid biosynthesis inhibitors

The synthesis of a new set of triazole bisphosphonates 8a-d and 9a-d presenting an alkyl or phenyl substituent at the C-4 or C-5 position of the triazole ring is described. These compounds have been evaluated for their antiproliferative activity against MIA PaCa-2 (pancreas), MDA-MB-231 (breast) and A549 (lung) human tumor cell lines. 4-hexyl- and 4-octyltriazole bisphosphonates 8b-c both displayed remarkable antiproliferative activities with IC₅₀ values in the micromolar range (0.75-2.4 μM) and were approximately 4 to 12-fold more potent than zoledronate. Moreover, compound 8b inhibits geranylgeranyl pyrophosphate biosynthesis in MIA PaCa-2 cells which ultimately led to tumor cells death.

12b80 - Hydroxybisphosphonate Linked Doxorubicin: Bone Targeted Strategy for Treatment of Osteosarcoma

To reply to as yet unmet medical needs to treat osteosarcoma, a form of primary bone cancer, we conceived the 12b80 compound by covalently conjugating antineoplastic compound doxorubicin to a bone targeting hydroxybisphosphonate vector and turned it into a prodrug through a custom linker designed to specifically trigger doxorubicin release in acidic bone tumor microenvironment. Synthesis of 12b80 was thoroughly optimized to be produced at gram scale. 12b80 was evaluated in vitro for high bone support affinity, specific release of doxorubicin in acidic condition, lower cytotoxicity, and cellular uptake of the prodrug. In vivo in rodents, 12b80 displayed rapid and sustained targeting of bone tissue and tumor-associated heterotopic bone and permitted a higher doxorubicin payload in tumor bone environment compared to nonvectorized doxorubicin. Consequently, 12b80 showed much lower toxicity compared to doxorubicin, promoted strong antitumor effects on rodent orthotopic osteosarcoma, displayed a dose-response therapeutic effect, and was more potent than doxorubicin/zoledronate combination.

A convenient synthetic route towards H-bisphosphinates

A practical generalisable procedure to synthesize hydroxymethylene H-bisphosphinates has been optimised. Unlike previous reports, numerous alkyl (including an alendronate bisphosphinate analogue) or (hetero)aryl compounds were rapidly obtained in satisfactory to excellent yields. A side product could have been identified as a phosphino-phosphonate isomer and plausible mechanistic pathways are proposed here. Moreover to check the literature data, a pKa value study was also performed.

Hybrid Au@alendronate nanoparticles as dual chemo-photothermal agent for combined cancer treatment

A gold therapeutic nanoplatform with the same molecule used as reductant, coating and therapeutic agent has been developed in a one-pot, one-phase process using alendronate, a drug from the bisphosphonate family known for its antitumor effects. In addition, the core made of gold nanoparticles (NPs) brings thermal functionalities under irradiation within the first biological window (650-900 nm). The Au@alendronate nanoplatform thus provided a combined antitumor activity through drug delivery and photothermal therapy. Au@alendronate NPs inhibited in vitro the proliferation of prostate cancer cells (PC3) in a dose-dependent manner, with an IC₅₀ value of 100 µM. Under NIR irradiation a temperature increase was observed leading to a reduction of the IC₅₀ value to 1 µM, with total tumor cell death at 100 µM.

Tumor-suppressive effects of atelocollagen-conjugated hsa-miR-520d-5p on un-differentiated cancer cells in a mouse xenograft model

Background

We previously demonstrated that hsa-miR-520d-5p can convert cancer cells into induced pluripotent stem cells (iPSCs) or mesenchymal stem cells (MSCs) via a demethylation process and p53 upregulation in vivo. Additionally, we have reported the non-tumorigenic effect of miR-520d-5p on normal human cells, including fibroblasts.

Methods

We used atelocollagen-conjugated miR-520d-5p (520d/atelocollagen) to confirm the possibility of a therapeutic effect on cancer cells. We traced the size and signal intensity of GFP-expressing tumors in mice each week, beginning 4 weeks after subcutaneous inoculation.

Results

520d/atelocollagen treatment suppressed tumor growth by greater than 80 % each week relative to controls and resulted in an approximately 30 % disappearance of tumors. In mice whose tumors disappeared, the existence of human genomic material at the injection site was examined by quantitative Alu-PCR, and we confirmed the co-existence of both species-derived cells. In every site where a tumor disappeared in immunodeficient mice, GFP protein was expressed in the connective tissues, and approximately 0.1 % of the extracted DNA contained human genomic material. We could not identify any adverse effects in vivo.

Conclusions

This is the first report to confirm an inhibitory effect of 520d/atelocollagen on cancer cells in vivo. The development of optimized modifications of this carrier is expected to enhance the efficiency of entry into tumor cells and the induction of its inhibitory effect.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2467-y) contains supplementary material, which is available to authorized users.

Synthesis of novel polymerizable molecules bearing bisphosphonate

In recent years, bisphosphonate chemistry has undergone an exponential growth due to the potential applications of these compounds in medicine and nanobiomaterial research. In this paper we describe the synthesis methods of different families of methacrylic monomers bearing a bisphosphonate with varying lengths of the chain, PEG linkers and more or less hydrolysable functions such as ester, carbamate or amide.

MDA-MB-231 breast cancer cells overexpressing single VEGF isoforms display distinct colonisation characteristics

Background:

Vascular endothelial growth factor (VEGF) is a multifunctional cytokine that has important roles in angiogenesis. Our knowledge of the significance of VEGF isoforms in human cancer remains incomplete.

Methods:

Bioluminescence imaging and transcriptomic analysis were used to study the colonisation capacity of the human breast cancer cells MDA-MB-231 controlling or overexpressing the VEGF165 or VEGF189 isoform (named cV-B, V165-B and V189-B, respectively) in nude mice.

Results:

When injected into the bloodstream, V189-B cells induced less metastasis in the lungs and bone than V165-B and cV-B control cells, consistent with longer survival of these mice and delay in tumour uptake in the mice injected with a V189-B clone. Histological analysis confirmed that there were less αSMA-positive cells in the lungs of the mice injected with V189-B. In vitro V189-B cells decreased both cell invasion and survival. Using transcriptomic analysis, we identified a subset of 18 genes expressed differentially between V189 and V165 cell lines and in 120 human breast tumours. V165 was associated with poor prognosis, whereas V189 was not, suggesting a complex regulation by VEGF isoforms. Our results showed a negative correlation between the expression pattern of VEGF189 and the levels of expression of seven genes that influence metastasis.

Conclusion:

Our findings provide the first evidence that VEGF isoforms have different effects on breast cancer cell line colonisation in vivo.

Structural requirements for bisphosphonate binding on hydroxyapatite: NMR study of bisphosphonate partial esters

Eighteen different bisphosphonates, including four clinically used bisphosphonate acids and their phosphoesters, were studied to evaluate how the bisphosphonate structure affects binding to bone. Bisphosphonates with weak bone affinity, such as clodronate, could not bind to hydroxyapatite after the addition of one ester group. Medronate retained its ability to bind after the addition of one ester group, and hydroxy-bisphosphonates could bind even after the addition of two ester groups. Thus, several bisphosphonate esters are clearly bone binding compounds. The following conclusions about bisphosphonate binding emerge: (1) a hydroxyl group in the geminal carbon takes part in the binding process and increases the bisphosphonate's ability to bind to bone; (2) the bisphosphonate's ability to bind decreases when the amount of ester groups increases; and (3) the location of the ester groups affects the bisphosphonate's binding ability.

Bisphosphonate prodrugs: synthesis and biological evaluation in HuH7 hepatocarcinoma cells

We investigated the biological effects of new synthesized bisphosphonates (BPs) on HuH7 hepatocarcinoma cells. BPs containing p-bromophenyl (R1 = p-Br, Ph, 2) in their side chain were the more potent to inhibit HuH7 cell viability. In addition, phenyl diesterified analogues (R2 = R3 = Ph, 2a) were more potent than methyl (R2 = R3 = Me, 2b) or non-esterified BPs (2) inducing more necrosis suggesting that they better entered into cells. Phosphodiesterase inhibitor (IBMX) reversed the effect of the esterified BPs and not that of non-esterified ones suggesting role of cell phosphodiesterases to release active BPs. BP analogues inhibited HuH7 cell migration but esterified ones had no effect on invasion due to the hiding of phosphonic groups. All together, these results indicated the therapeutic interest of these new BP prodrugs.

Overexpression of VEGF189 in breast cancer cells induces apoptosis via NRP1 under stress conditions

The existence of multiple VEGF-A isoforms raised the possibility that they may have distinct functions in tumor growth. We have previously published that VEGF189 and VEGF165 contribute to breast cancer progression and angiogenesis, but VEGF165 induced the most rapid tumor uptake. Since VEGF165 has been described as a survival factor for breast tumor cells, we questioned here the effects of VEGF189 on the survival/apoptosis of MDA-MB-231 cells. We used clones which overexpress VEGF189 (V189) or VEGF165 (V165) isoforms and compared them to a control one (cV). Overexpression of VEGF189 resulted in increased cell apoptosis, as determined by Annexin-V apoptosis assay, under serum starvation and doxorubicin treatment, while VEGF 165 was confirmed to be a survival factor. Since MDA-MB-231 highly express NRP1 (a co-receptor for VEGF-A), we used short hairpin RNA (shRNA) to knockdown NRP1 expression. V189shNRP1 clones were characterized by reduced apoptosis and higher necrosis, as compared to V189shCtl, under stress conditions. Unexpectedly, NRP1 knock-down had no effect on the survival or apoptosis of V165 cells. VEGF189 showed greater affinity towards NRP1 than VEGF165 using a BIAcore binding assay. Finally, since endogenously produced urokinase-type plasminogen (uPA) has been found to prevent apoptosis in breast cancers, we analyzed the level of uPA activity in our clones. An inhibition of uPA activity was observed in V189shNRP1 clones. Altogether, these results suggest a major role of NRP1 in apoptosis induced by VEGF189 in stress conditions and confirm VEGF165 as a survival factor.

Invading basement membrane matrix is sufficient for MDA-MB-231 breast cancer cells to develop a stable in vivo metastatic phenotype

INTRODUCTION

The poor efficacy of various anti-cancer treatments against metastatic cells has focused attention on the role of tumor microenvironment in cancer progression. To understand the contribution of the extracellular matrix (ECM) environment to this phenomenon, we isolated ECM surrogate invading cell populations from MDA-MB-231 breast cancer cells and studied their genotype and malignant phenotype.

METHODS

We isolated invasive subpopulations (INV) from non invasive populations (REF) using a 2D-Matrigel assay, a surrogate of basal membrane passage. INV and REF populations were investigated by microarray assay and for their capacities to adhere, invade and transmigrate in vitro, and to form metastases in nude mice.

RESULTS

REF and INV subpopulations were stable in culture and present different transcriptome profiles. INV cells were characterized by reduced expression of cell adhesion and cell-cell junction genes (44% of down regulated genes) and by a gain in expression of anti-apoptotic and pro-angiogenic gene sets. In line with this observation, in vitro INV cells showed reduced adhesion and increased motility through endothelial monolayers and fibronectin. When injected into the circulation, INV cells induced metastases formation, and reduced injected mice survival by up to 80% as compared to REF cells. In nude mice, INV xenografts grew rapidly inducing vessel formation and displaying resistance to apoptosis.

CONCLUSION

Our findings reveal that the in vitro ECM microenvironment per se was sufficient to select for tumor cells with a stable metastatic phenotype in vivo characterized by loss of adhesion molecules expression and induction of pro-angiogenic and survival factors.