Antitumor effects of bisphosphonates

The assessment of halitosis with a new screening tool in medication-related osteonecrosis of the jaw

OBJECTIVES

This study aimed to identify the levels of halitosis in patients with Medication-related osteonecrosis of the jaw (MRONJ) and osteoporosis and to suggest a new MRONJ screening method using halitosis measurement.

MATERIALS AND METHODS

From October 2019 to April 2023, participants aged 19 years or older without periodontal disease were selected. Seventy-five participants, 25 in each group, were divided into an MRONJ group, an osteoporosis group without MRONJ, and a control group without osteoporosis and not taking osteoporosis drugs or antibiotics. Each participant underwent halitosis assessment twice using an exhaled breath analyzer to measure halitosis twice by blowing a straw for 1 min. Measured concentrations of hydrogen, hydrogen sulfide, and methyl mercaptan were compared between groups.

RESULTS

Data from 22 patients in the MRONJ group, 25 in the osteoporosis group, and 25 in the control group were analyzed. The concentrations of hydrogen sulfide and methyl mercaptan were significantly higher in the MRONJ group than in the other groups, but the concentrations of hydrogen did not differ between the groups. When comparing the concentrations of hydrogen sulfide and methyl mercaptan in osteoporosis patients and solid cancer patients in the MRONJ group, there was a significant difference in hydrogen sulfide concentration, but there was no significant difference in methyl mercaptan.

CONCLUSIONS

Quantifying the level of halitosis can be used to screen for MRONJ in patients taking bisphosphonates, such as patients with osteoporosis, prostate cancer, and breast cancer.

CLINICAL RELEVANCE

MRONJ is accompanied by bad breath, and the concentrations of hydrogen sulfide and methyl mercaptan are associated with MRONJ.

Medication-related osteonecrosis of the jaw using periodontitis-induced rat before tooth extraction

OBJECTIVE

This study aimed to investigate the occurrence of medication-related osteonecrosis of the jaw (MRONJ) after tooth extraction due to periodontitis in ovariectomized rats.

METHODS

Twenty-four osteoporosis-induced rats were administered with zoledronic acid (ZA; ZA group) or saline (CONT group). In both groups, tooth extraction was performed after inducing periodontitis, and all animals were sacrificed 8-week after tooth extraction.

RESULTS

Micro-CT of the tibia showed that the bone volume fraction, bone surface density, trabecular number, and bone mineral density were significantly higher in the ZA group than in the CONT group. Histologically, the proliferative zone on the growth plate was thicker in the ZA group than in the CONT group. Micro-CT of the extraction sites revealed that the bone volume fraction was significantly higher in the ZA group than in the CONT group. Radiologically, the ZA group showed partial healing and delayed healing. Histological analysis revealed normal bone healing status with completely healed epithelium in the extraction sites of the CONT group, whereas abnormal empty osteocytes in the necrotic bone and inflammatory infiltration were observed in the ZA group.

CONCLUSION

The incidence of MRONJ increased in the rats administered with ZA.

Efficacy of zoledronic acid for the elimination of disseminated tumor cells in a clinically relevant, spontaneously metastatic prostate cancer xenograft model

Bone metastases develop in >90 % of patients with castration-resistant prostate cancer (PCa) through complex interactions between the bone microenvironment and tumor cells. Previous androgen-deprivation therapy (ADT), which is known to cause bone loss, as well as anti-resorptive agents such as zoledronic acid (ZA), used to prevent skeletal complications, may influence these interactions and thereby the growth of disseminated tumor cells (DTC) in the bone marrow (BM). Here, a spontaneously metastatic xenograft tumor model of human PCa was further optimized to mimic the common clinical situation of ADT (castration) combined with primary tumor resection in vivo. The effects of these interventions, alone or in combination with ZA treatment, on tumor cell dissemination to the BM and other distant sites were analyzed. Metastatic burden was quantified by human-specific Alu-qPCR, bioluminescence imaging (BLI), and immunohistochemistry. Further, bone remodeling was assessed by static histomorphometry and serum parameters. Initial comparative analysis between NSG and SCID mice showed that spontaneous systemic dissemination of subcutaneous PC-3 xenograft tumors was considerably enhanced in NSG mice. Primary tumor resection and thereby prolonged observational periods resulted in a higher overall metastatic cell load at necropsy and tumor growth alone caused significant bone loss, which was further augmented by surgical castration. In addition, castrated mice showed a strong trend towards higher bone metastasis loads. Weekly treatment of mice with ZA completely prevented castration- and tumor-induced bone loss but had no effect on bone metastasis burden. Conversely, the total lung metastasis load as determined by BLI was significantly decreased upon ZA treatment. These findings provide a basis for future research on the role of ZA not only in preventing skeletal complications but also in reducing metastasis to other organs.

Phytochemicals and mitochondria: Therapeutic allies against gastric cancer

BACKGROUND

Mitochondria are the energy factories of cells with the ability to modulate the cell cycle, cellular differentiation, signal transduction, growth, and apoptosis. Existing drugs targeting mitochondria in cancer treatment have disadvantages of drug resistance and side effects. Phytochemicals, which are widely found in plants, are bioactive compounds that could facilitate the development of new drugs for gastric cancer. Studies have shown that some phytochemicals can suppress the development of gastric cancer.

METHODS

We searched for data from PubMed, China National Knowledge Infrastructure, Web of Science, and Embase databases from initial establishment to December 2021 to review the mechanism by which phytochemicals suppress gastric cancer cell growth by modulating mitochondrial function. Phytochemicals were classified and summarized by their mechanisms of action.

RESULTS

Phytochemicals can interfere with mitochondria through several mechanisms to reach the goal of promoting apoptosis in gastric cancer cells. Some phytochemicals, e.g., daidzein and tetrandrine promoted cytochrome c spillover into the cytoplasm by modulating the members of the B-cell lymphoma-2 protein family and induced apoptotic body activity by activating the caspase protein family. Phytochemicals (e.g., celastrol and shikonin) could promote the accumulation of reactive oxygen species and reduce the mitochondrial membrane potential. Several phytochemicals (e.g., berberine and oleanolic acid) activated mitochondrial apoptotic submission via the phosphatidylinositol-3-kinase/Akt signaling pathway, thereby triggering apoptosis in gastric cancer cells. Several well-known phytochemicals that target mitochondria, including berberine, ginsenoside, and baicalein, showed the advantages of multiple targets, high efficacy, and fewer side effects.

CONCLUSIONS

Phytochemicals could target the mitochondria in the treatment of gastric cancer, providing potential directions and evidence for clinical translation. Drug discovery focused on phytochemicals has great potential to break barriers in cancer treatment.

Bone Health Management in the Continuum of Prostate Cancer Disease

Prostate cancer (PCa) is the second-leading cause of cancer-related deaths in men. PCa cells require androgen receptor (AR) signaling for their growth and survival. Androgen deprivation therapy (ADT) is the preferred treatment for patients with locally advanced and metastatic PCa disease. Despite their initial response to androgen blockade, most patients eventually will develop metastatic castration-resistant prostate cancer (mCRPC). Bone metastases are common in men with mCRPC, occurring in 30% of patients within 2 years of castration resistance and in >90% of patients over the course of the disease. Patients with mCRPC-induced bone metastasis develop lesions throughout their skeleton; the 5-year survival rate for these patients is 47%. Bone-metastasis-induced early changes in the bone that proceed the osteoblastic response in the bone matrix are monitored and detected via modern magnetic resonance and PET/CT imaging technologies. Various treatment options, such as targeting osteolytic metastasis with bisphosphonates, prednisone, dexamethasone, denosumab, immunotherapy, external beam radiation therapy, radiopharmaceuticals, surgery, and pain medications are employed to treat prostate-cancer-induced bone metastasis and manage bone health. However, these diagnostics and treatment options are not very accurate nor efficient enough to treat bone metastases and manage bone health. In this review, we present the pathogenesis of PCa-induced bone metastasis, its deleterious impacts on vital organs, the impact of metastatic PCa on bone health, treatment interventions for bone metastasis and management of bone- and skeletal-related events, and possible current and future therapeutic options for bone management in the continuum of prostate cancer disease.

Repurposing therapeutics for malignant pleural mesothelioma (MPM) - Updates on clinical translations and future outlook

INTRODUCTION

Malignant pleural mesothelioma (MPM) is a rare malignancy affecting the mesothelial cells in the pleural lining surrounding the lungs. First approved chemotherapy against MPM was a platinum/antifolate (cisplatin/pemetrexed) (2003). Since then, no USFDA approvals have gone through for small molecules as these molecules have not been proven to be therapeutically able in later stages of clinical studies. An alternative to conventional chemotherapy can be utilization of monoclonal antibodies, which are proven to improve patient survival significantly as compared to conventional chemotherapy (Nivolumab + Ipilimumab, 2020).

AREA COVERED

Drug repurposing has been instrumental in drug discovery for rare diseases such as MPM and multiple repositioned small molecule therapies and immunotherapies are currently being tested for its applicability in MPM management. This article summarizes essential breakthroughs along the pre-clinical and clinical developmental stages of small molecules and monoclonal antibodies for MPM management.

EXPERT OPINION

For rare diseases such as malignant pleural mesothelioma, a drug repurposing strategy can be adapted as it eases the financial burden on pharmaceutical companies along with fast-tracking development. With the rise of multiple small molecule repurposed therapies and innovations in localized treatment, MPM therapeutics are bound to be more effective in this decade.

Bone targeted new zoledronate derivative: design, synthesis, 99mTc-coupling, in-silico study and preclinical evaluation for promising osteosarcoma therapy

Background: Zoledronate suppresses human sarcomas by blocking the formation of geranylgeranyl diphosphate (GGPP) via inhibiting GGPP synthase.Objectives: Designing of new derivative of dronic acid (1-hydroxy-2-(4-nitro-1H-imidazol-1-yl)ethan-1,1-diyl)bis phosphonic acid), structurally related to zoledronate to be used for osteosarcoma therapy.Methods: 1-hydroxy-2-(4-nitro-1H-imidazol-1-yl)ethan-1,1-diyl)bis(phosphonic acid) was synthesized in one pot reaction with a yield of 65 ± 4%. The synthesized nitro-zoledronate compound was successfully radiolabeled with 99mTc with a radiochemical purity of 92.05%. Docking accuracy and scoring reliability for the new nitro-zoledronate with human GGPPS using MOE software has been presented.Results and Conclusion: The nitro-zoledronate successfully coupled with technetium-99m at high yield to investigate its in-vivo biodistribution which indicated highly selective uptake in the skeletal system and rapid clearance from soft tissues. The in-vitro cytotoxicity of the nitro-zoledronate was evaluated and potently inhibited the osteosarcoma cell line (MG-63) after 72 hours with an IC50 value of 10 μM. To summarize, our data point to a promising candidate to improve osteosarcoma therapy.

Monitoring and Management of Fibrodysplasia Ossificans Progressiva: Current Perspectives

Fibrodysplasia ossificans progressiva (FOP), sometimes known as myositis ossificans progressiva, is an ultra-rare disease in which bone is formed in muscular tissue, tendons and ligaments. This is known as heterotopic ossification (HO). FOP is caused by a heterozygous mutation in the highly conserved ACVR1/ALK2 gene which affects about 1 in 1.5–2 million individuals. At birth, patients with the predominant R206H mutation only exhibit a bilateral hallux valgus. During childhood, heterotopic bone formation develops in a typical pattern, affecting the axial muscles first before appendicular body parts are involved. HO can start spontaneously but is often elicited by soft tissue trauma or medical procedures. After soft tissue injury, an inflammatory process called a flare-up can start, followed by the formation of HO. HO leads to a limited range of motion, culminating in complete ankylosis of nearly all joints. As a result of HO surrounding the thorax, patients often suffer from thoracic insufficiency syndrome (TIS). TIS is the most common cause of a limited life expectancy for FOP patients, with a median life expectancy of 56 years. Management is focused on preventing soft-tissue injury that can provoke flare-ups. This includes prevention of iatrogenic damage by biopsies, intramuscular injections and surgery. Anti-inflammatory medication is often started when a flare-up occurs but has a poor basis of evidence. Several forms of potential treatment for FOP are being researched in clinical trials. Progression of the disease is monitored using CT and 18F-NaF PET/CT combined with functional assessments. Patients are regularly evaluated for frequently occurring complications such as restrictive lung disease. Here, we review the current management, monitoring and treatment of FOP.

Qualitative focus group interview study of communication between patients, dentists and physicians for efficient osteonecrosis of the jaw practices

OBJECTIVES

To investigate problems and the current status of existing methods of communication between patients, dentists and physicians for the prevention and treatment of medication-related osteonecrosis of the jaw (MRONJ).

DESIGN

A focus group interview study with a descriptive design using qualitative content analysis of transcripts.

SETTING

Secondary care in Korea.

PARTICIPANTS

3 patient groups and 4 health professional groups in a total of 32 participants including patients with osteoporosis or bone metastasis, dentists and physicians.

RESULTS

This study revealed that patients lacked medical knowledge of osteoporosis drugs, whereas dentists and physicians lacked each other's expertise. All patients reported undergoing dental treatments during the osteoporosis drug treatment, but dentists and physicians had different MRONJ experiences depending on their work setting in primary or secondary care. Patients expressed dissatisfaction with the current system of communication with health professionals via letter as they found this to be a slow process. Dentists and physicians reported the need for effective communication because they felt defensive when sending and receiving medical consults.

CONCLUSIONS

Despite the low incidence of MRONJ among patients with osteoporosis, it is difficult to treat; thus, it is necessary to inform dentists, physicians and patients about the importance of MRONJ prevention. To this end, close communication among all involved stakeholders about osteoporosis drugs is required.

Apamin-Conjugated Alendronate Sodium Nanocomplex for Management of Pancreatic Cancer

Pancreatic cancer has a low survival rate and has limited therapeutic options due to the peculiarity of the tumor tissue. Cancer nanotechnology provides several opportunities to resolve such difficulties as a result of the high surface-to-volume ratio of nanostructures. Peptide-drug nanocomplexes have proved to have immense potential in anticancer activity against pancreatic cancer cells. Thus, in the present study apamin (APA) and alendronate sodium (ALS) were combined to form nanocomplexes (APA-ALS-NC) against pancreatic cancer cells. Optimization of ALS, incubation time, and sonication time in terms of particle size of the nanocomplex was carried out. The optimized formulation was evaluated for anticancer activities in pancreatic cancer cells (PANC-1 cells). A Box-Behnken design using ALS, incubation time, and sonication time as independent factors and particle size as the response was chosen to optimize the APA-ALS-NC formulation. The optimized APA-ALS-NC had a particle size of 161.52 ± 8.4 nm. The evaluation of APA-ALS-NC in PANC-1 cells was carried out using various in vitro tests. The IC₅₀ values were determined by MTT assay and found to be 37.6 ± 1.65, 13.4 ± 0.59, and 1.01 ± 0.04 µg/mL for ALS, APA, and APA-ALS-NC, respectively. The higher cytotoxicity activity of APA-ALS-NC was confirmed from the higher percentage of cells in the necrosis phase (apoptosis study) and the G2-M phase (cell cycle study) compared to that of ALS and APA. While the loss of mitochondrial membrane potential was less for APA-ALS-NC, the levels of IL-1β, TNF-α, caspase-3, ROS, IL-6, and NF-kB showed that APA-ALS-NC can significantly enhance apoptosis and cytotoxicity in PANC-1 cells. Moreover, Bax (10.87 ± 1.36), Bcl-2 (0.27 ± 0.02), and p53 (9.16 ± 1.22) gene expressions confirmed that APA-ALS-NC had a significant apoptotic effect compared to ALS and APA. In summary, the APA-ALS-NC had a more significant cytotoxic effect than ALS and APA. The results of the present study are promising for further evaluation in pre-clinical and clinical trials for arriving at a successful therapeutic strategy against pancreatic cancer.

Gamabufotalin Inhibits Osteoclastgenesis and Counteracts Estrogen-Deficient Bone Loss in Mice by Suppressing RANKL-Induced NF-κB and ERK/MAPK Pathways

Osteolytic bone disease is a condition of imbalanced bone homeostasis, characterized mainly by excessive bone-resorptive activity, which could predispose these populations, such as the old and postmenopausal women, to developing high risk of skeletal fragility and fracture. The nature of bone homeostasis is the coordination between the osteoblasts (OBs) and osteoclasts (OCs). Abnormal activation of osteoclasts (OCs) could compromise the bone homeostasis, constantly followed by a clutch of osteolytic diseases, including postmenopausal osteoporosis, osteoarthritis, and rheumatoid arthritis. Thus, it is imperatively urgent to explore effective medical interventions for patients. The traditional Chinese medicine (TCM) gamabufotalin (CS-6) is a newly identified natural product from Chansu and has been utilized for oncologic therapies owing to its good clinical efficacy with less adverse events. Previous study suggested that CS-6 could be a novel anti-osteoporotic agent. Nevertheless, whether CS-6 suppresses RANK-(receptor activator of nuclear factor-κ B ligand)/TRAF6 (TNF receptor-associated factor 6)-mediated downstream signaling activation in OCs, as well as the effects of CS-6 on OC differentiation in vivo, remains elusive. Therefore, in this present study, we aimed to explore the biological effects of CS-6 on osteoclastogenesis and RANKL-induced activation of related signaling pathways, and further to examine the potential therapeutic application in estrogen-deficient bone loss in the mice model. The results of in vitro experiment showed that CS-6 can inhibit RANKL-induced OC formation and the ability of bone resorption in a dose-dependent manner at both the early and late stages of osteoclastogenesis. The gene expression of OC-related key genes such as tartrate-resistant acid phosphatase (TRAP), CTSK, DC-STAMP, MMP9, and β3 integrin was evidently reduced. In addition, CS-6 could mitigate the systemic estrogen-dependent bone loss and pro-inframammary cytokines in mice in vivo. The molecular mechanism analysis suggested that CS-6 can suppress RANKL/TRAF6-induced early activation of NF-κB and ERK/MAPK signaling pathways, which consequently suppressed the transcription activity of c-Fos and NFATc1. Taken together, this present study provided ample evidence that CS-6 has the promise to become a therapeutic candidate in treating osteolytic conditions mediated by elevated OC formation and bone resorption.

Zoledronic Acid-Loaded β-TCP Inhibits Tumor Proliferation and Osteoclast Activation: Development of a Functional Bone Substitute for an Efficient Osteosarcoma Treatment

Osteosarcoma has a poor survival rate due to relapse and metastasis. Zoledronic acid (ZOL), an anti-resorptive and anti-tumor agent, is used for treating osteosarcoma. Delivery of ZOL to the target region is difficult due to its high binding affinity to bone minerals. This study developed a novel treatment for osteosarcoma by delivering ZOL to the target region locally and sustainably. In this study, we fabricated a novel bone substitute by loading ZOL on β-tricalcium phosphate (β-TCP). The ZOL-loaded β-TCP (ZOL/β-TCP) would be expected to express the inhibitory effects via both bound-ZOL (bound to β-TCP) and free-ZOL (release from ZOL/β-TCP). To explore the ability to release ZOL from the ZOL/β-TCP, the amount of released ZOL was measured. The released profile indicates that a small amount of ZOL was released, and most of it remained on the β-TCP. Our data showed that ZOL/β-TCP could successfully express the effects of ZOL via both bound-ZOL and free-ZOL. In addition, we examined the biological effects of bound/free-ZOL using osteosarcoma and osteoclasts (target cells). The results showed that two states of ZOL (bound/free) inhibit target cell activities. As a result, ZOL/β-TCP is a promising candidate for application as a novel bone substitute.

The effects of bisphosphonate and radiation therapy in bone-metastatic lung adenocarcinoma: the impact of KRAS mutation

Background

KRAS mutation is the most common genetic alteration in lung adenocarcinoma (LADC) in Western countries and is associated with worse outcome in bone-metastatic cases. Yet, to date, no effective treatment guidelines were developed for these patients. Accordingly, our aim was to investigate the impact of KRAS mutation on bisphosphonate (BTx) and radiation therapy (RTx) in bone-metastatic LADC patients.

Methods

Clinicopathological variables of 134 consecutive LADC patients with bone metastases at diagnosis and known KRAS status were retrospectively analyzed. The effects of BTx, RTx and KRAS mutation on overall survival (OS) were investigated.

Results

Of the total cohort, 93 patients were identified as KRAS wild-type (WT) (69.4%) and 41 (30.6%) as KRAS mutant patients. The presence of KRAS mutation was associated with significantly reduced median OS (5.1 vs. 10.2 months in KRAS WT patients; P=0.008). Irrespective of KRAS mutational status both BTx (P=0.007) and RTx (P=0.021) conferred a significant benefit for OS. Notably, however, when analyzing the patients with KRAS-mutant and KRAS WT tumors separately, the benefit from BTx and RTx on OS remained statistically significant only in KRAS WT patients (P=0.032 and P=0.031, respectively).

Conclusions

KRAS mutation is a strong negative prognostic factor in bone-metastatic LADC patients. Both BTx and RTx can increase the OS with a pronounced benefit for patients with KRAS WT tumors. Altogether, KRAS mutational status should be considered during therapeutic decision making in bone-metastatic LADC patients.

Synthesis and biological evaluation of indolylglyoxylamide bisphosphonates, antimitotic microtubule-targeting derivatives of indibulin with improved aqueous solubility

Indibulin (D-24851) derivatives with bisphosphonate fragment connected to the N1 atom of imidazole ring were synthesized by alkylation of (indolyl-3)methylglyoxylates with ethylenebisphosphonate. Biological evaluation of targeted compounds 4a-d using the phenotypic sea urchin embryo assay provided evidence that replacing of p-chlorobenzene ring in indibulin by bisphosphonate group did not eliminate antimitotic microtubule destabilizing activity. The most active molecule, tetraacid 5a, at physiological pH formed tetrasodium salt 6a with aqueous solubility value of at least 10 mg/mL. Molecule 5a was more potent in the sea urchin embryo assay than the parent indibulin. This compound also exhibited pronounced cytotoxicity against A549 lung carcinoma and A375 melanoma cell lines.

Genomic Medicine: Lessons Learned From Monogenic and Complex Bone Disorders

Current genetic studies of monogenic and complex bone diseases have broadened our understanding of disease pathophysiology, highlighting the need for medical interventions and treatments tailored to the characteristics of patients. As genomic research progresses, novel insights into the molecular mechanisms are starting to provide support to clinical decision-making; now offering ample opportunities for disease screening, diagnosis, prognosis and treatment. Drug targets holding mechanisms with genetic support are more likely to be successful. Therefore, implementing genetic information to the drug development process and a molecular redefinition of skeletal disease can help overcoming current shortcomings in pharmaceutical research, including failed attempts and appalling costs. This review summarizes the achievements of genetic studies in the bone field and their application to clinical care, illustrating the imminent advent of the genomic medicine era.

Therapeutic Dimensions of Bisphosphonates: A Clinical Update

Bisphosphonates (BPs) are a commonly used class of drugs for the treatment of bone disorders. An extensive review of BPs with their clinical efficacy and safety profile is unavailable. This study aimed to review the available literature on BPs, summarize their role in clinical therapy, and emphasize their safety profile. Authors reviewed the existing literature using the Google Scholar, PubMed, and Micromedex databases and analyzed the collected articles. BPs are the preferred medication for osteoporosis and other similar conditions owing to their efficient antiosteoclastic activity. Few of them are available in oral dosage forms; hence, they are patient-friendly. The mechanism of action, common adverse effects and their clinical applications, precautions and warnings pertaining to the route of administration, and safety profiles have been discussed in this manuscript. The common adverse effects are majorly related to the gastrointestinal, cardiovascular, and endocrine system. Upon chronic usage, patients may experience serious problems like osteonecrosis of the jaw and atypical bone fractures. Although BPs are effective and safe, they may cause GI adverse effects and rare cases of osteonecrosis. Patient counseling could prove beneficial in early identification and prevention of the adverse effects associated with BPs.

Targeting SREBP-2-Regulated Mevalonate Metabolism for Cancer Therapy

Recently, targeting metabolic reprogramming has emerged as a potential therapeutic approach for fighting cancer. Sterol regulatory element binding protein-2 (SREBP-2), a basic helix-loop-helix leucine zipper transcription factor, mainly regulates genes involved in cholesterol biosynthesis and homeostasis. SREBP-2 binds to the sterol regulatory elements (SREs) in the promoters of its target genes and activates the transcription of mevalonate pathway genes, such as HMG-CoA reductase (HMGCR), mevalonate kinase and other key enzymes. In this review, we first summarized the structure of SREBP-2 and its activation and regulation by multiple signaling pathways. We then found that SREBP-2 and its regulated enzymes, including HMGCR, FPPS, SQS, and DHCR4 from the mevalonate pathway, participate in the progression of various cancers, including prostate, breast, lung, and hepatocellular cancer, as potential targets. Importantly, preclinical and clinical research demonstrated that fatostatin, statins, and N-BPs targeting SREBP-2, HMGCR, and FPPS, respectively, alone or in combination with other drugs, have been used for the treatment of different cancers. This review summarizes new insights into the critical role of the SREBP-2-regulated mevalonate pathway for cancer and its potential for targeted cancer therapy.

Drug repositioning in cancer: The current situation in Japan

Cancer is a leading cause of death worldwide, and the incidence continues to increase. Despite major research aimed at discovering and developing novel and effective anticancer drugs, oncology drug development is a lengthy and costly process, with high attrition rates. Drug repositioning (DR, also referred to as drug repurposing), the process of finding new uses for approved noncancer drugs, has been gaining popularity in the past decade. DR has become a powerful alternative strategy for discovering and developing novel anticancer drug candidates from the existing approved drug space. Indeed, the availability of several large established libraries of clinical drugs and rapid advances in disease biology, genomics/transcriptomics/proteomics and bioinformatics has accelerated the pace of activity‐based, literature‐based and in silico DR, thereby improving safety and reducing costs. However, DR still faces financial obstacles in clinical trials, which could limit its practical use in the clinic. Here, we provide a brief review of DR in cancer and discuss difficulties in the development of DR for clinical use. Furthermore, we introduce some promising DR candidates for anticancer therapy in Japan.

Aminobisphosphonate-treated ewes as a model of osteonecrosis of the jaw and of dental implant failure

BACKGROUND

Bisphosphonate (BP)-related osteonecrosis of the jaw (BRONJ) and dental implant failure are two negative side effects of chronic aminoBP treatment.

METHODS

Eleven ovariectomized (OVX) ewes and four ewes subjected to sham surgery (SHAM) were treated as follows: OVX (n = 5): OVX plus saline solution; zoledronic acid-treated group (ZOL) (n = 6): OVX plus ZOL; SHAM (n = 4): SHAM plus saline solution. Extraction of the first upper molar was performed at 1 year, dental implant placement at 2 years, and sacrifice at 28 months.

RESULTS

Implants remained in place in SHAM and OVX ewes but were lost in all ZOL ewes. ZOL sheep (2/6) showed inflammation and necrotic bone at mandibular region. No differences in serum calcium (Ca), inorganic phosphate (Pi) or 25-hydroxyvitamin D were observed, whereas bone alkaline phosphatase levels decreased in the three studied groups (P < 0.05). The significantly lowest levels of carboxy-terminal telopeptide of type I collagen were observed in ZOL (P < 0.05), and showed no differences between SHAM and OVX. OVX showed the lowest and ZOL the highest Ca and Pi contents in femur and maxilla (P < 0.05). Bone volume (BV/TV%) and iliac crest were similar at baseline and at month 4. At the end of the study, BV/TV%, proximal femur and hemi-mandible bone mineral content and bone mineral density, and trabeculae number were similar in SHAM and ZOL, and lower in OVX (P < 0.05).

CONCLUSION

All ZOL-treated ewes on a schedule similar to that used in cancer patients showed extensive suppression of bone remodeling and implant failure. Some of the ZOL ewes developed BRONJ.

Bisphosphonates and primary breast cancer risk: an updated systematic review and meta-analysis involving 963,995 women

Importance

Prevention of primary breast cancer (BCa) in women is of great public health importance. The existing results from observational epidemiologic studies focused on the association between bisphosphonates and primary BCa risk have been inconsistent.

Objective

To update this systematic review and meta-analysis to assess the effect of bisphosphonates on primary BCa risk.

Data sources

We comprehensively searched MEDLINE, EMBASE, Cochrane libraries, ProQuest, and Web of Science through June 25, 2018 for relevant studies.

Study selection

Epidemiological studies that assessed the effect of bisphosphonates on the risk of primary BCa in women.

Data extraction and synthesis

We reported this meta-analysis according to the PRISMA guidelines. Available multivariable-adjusted effect estimates and corresponding 95% CIs were pooled with a random-effects model.

Main outcomes and measures

The prespecified main outcome was the risk of primary BCa.

Results

In total, five cohort studies involving 657,558 women and 12,991 primary BCa patients, three population-based case-control studies involving 54,701 primary BCa cases and 237,962 healthy controls and two randomized controlled trials (RCTs) involving 13,774 women and 165 primary BCa patients were included in this meta-analysis. Bisphosphonates were associated with a 12% decreased risk of primary BCa (RR, 0.88; 95% CI, 0.83–0.94). However, when we analyzed study designs separately, the pooled results from observational studies were inconsistent with that from RCTs. The observed association of primary BCa risk with long-term use (≥1 year) of bisphosphonates seemed to be more robust and stronger than that of short-term use (<1 year) (RR, 0.75; 95% CI, 0.66–0.84; and 0.90; 95% CI, 0.84–0.97; respectively).

Conclusion

This meta-analysis adds to the body of evidence for an association between bisphosphonates and a significantly decreased risk of primary BCa. However, future large-scale RCTs are required to validate this concern.

Antiproliferative and antimigratory activities of bisphosphonates in human breast cancer cell line MCF-7

Bisphosphonates (BPs) are antiresorptive drugs that act as effective inhibitors of cancer cell proliferation. However, not all bisphosphonates are equally effective against breast cancer cells in vitro. The present study investigated the extent to which three BPs decrease the viability of MCF-7 human breast cancer cells, stimulate cell apoptosis and inhibit cell migration by modulating proteins in the mevalonate pathway. The three BPs exerted direct anticancer effects against MCF-7 cells in a dose- and time-dependent manner, with pamidronate demonstrating the highest efficacy. In addition, the BPs inhibited colony formation ability. The activity of BPs against MCF-7 cells was inhibited by the mevalonate product geranylgeranyl pyrophosphate, which was potentiated by doxorubicin. It was also identified that BPs modulated Ras-related C3 botulinum toxin substrate 1, Ras homolog gene family member A and cell division control protein 42 homolog gene expression. Consistent with the observed growth inhibitory effects, BPs also inhibited the cell cycle by promoting G1 phase arrest and the downregulation of cyclin D1 and upregulation of p21. Additionally, BPs were revealed to induce reactive oxygen species expression, caspase-3 activity and increase the mitochondrial transmembrane potential, which was associated with apoptosis. BP-induced cancer cell apoptosis was detected by acridine orange/ethidium bromide staining and flow cytometry analysis, and was identified to be associated with the induction of caspase-3 and cytochrome c protein expression. Furthermore, BPs significantly decreased cancer cell migration in a dose-dependent manner and reduced matrix metallopeptidase-9 protein expression. In summary, the current study demonstrated that BPs exhibited a direct anticancer effect and an antimigratory effect on MCF-7 cells. These findings suggest that BPs may be developed as a therapeutic option for breast cancer and may serve as sensitizing chemotherapeutic agents.

Bisphosphonate Use in Pediatric Oncology for Pain Management

The use of bisphosphonates for pain control in children with cancer is not extensively studied. We retrospectively evaluated 35 children with cancer treated with intravenous bisphosphonates for pain management at a single institution from 1998 through 2015. We analyzed pain scores and opioid and adjuvant medication consumption before bisphosphonate administration, daily for 2 weeks, and at 3 and 4 weeks after administration. We also determined the time interval between diagnosis and first administration of bisphosphonates and duration of life after bisphosphonate administration. Mean pain scores were 2.45 (±2.96) and 0.75 (±1.69) before and 14 days after bisphosphonate administration, respectively ( P = .25), and morphine equivalent doses of opioids were 5.52 (±13.35) and 5.27 (±9.77), respectively ( P = .07). Opioid consumption was significantly decreased at days 4 to 8, days 11 to 12, and week 3 after first bisphosphonate administration. The median duration of life after first bisphosphonate administration was 80 days, indicating its use late in the course of treatment. Bisphosphonates did not significantly improve pain outcomes at 2 weeks, but opioid consumption was reduced at several time points during the first 3 weeks. The use of bisphosphonates earlier in the course of pediatric oncological disease should be evaluated in prospective investigations.

Drug repurposing in malignant pleural mesothelioma: a breath of fresh air?

Drug repurposing is the use of known drugs for new indications. Malignant pleural mesothelioma (MPM) is a rare cancer with a poor prognosis. So far, few treatments have been approved in this disease. However, its incidence is expected to increase significantly, particularly in developing countries. Consequently, drug repurposing appears as an attractive strategy for drug development in MPM, since the known pharmacology and safety profile based on previous approvals of repurposed drugs allows for faster time-to-market for patients and lower treatment cost. This is critical in low- and middle-income countries where access to expensive drugs is limited. This review assesses the published preclinical and clinical data about drug repurposing in MPM.In this review, we identified 11 therapeutic classes that could be repositioned in mesothelioma. Most of these treatments have been evaluated in vitro, half have been evaluated in vivo in animal models of MPM and only three (i.e. valproate, thalidomide and zoledronic acid) have been investigated in clinical trials, with limited benefits so far. Efforts could be coordinated to pursue further investigations and test promising drugs identified in preclinical experiments in appropriately designed clinical trials.

KRAS-mutation status dependent effect of zoledronic acid in human non-small cell cancer preclinical models

Background

In non-small cell lung cancer (NSCLC) KRAS-mutant status is a negative prognostic and predictive factor. Nitrogen-containing bisphosphonates inhibit prenylation of small G-proteins (e.g. Ras, Rac, Rho) and thus may affect proliferation and migration. In our preclinical work, we investigated the effect of an aminobisphosphonate compound (zoledronic acid) on mutant and wild type KRAS-expressing human NSCLC cell lines.

Results

We confirmed that zoledronic acid was unable to inhibit the prenylation of mutant K-Ras unlike in the case of wild type K-Ras. In case of in vitro proliferation, the KRAS-mutant human NSCLC cell lines showed resistance to zoledronic acid wild-type KRAS-cells proved to be sensitive. Combinatory application of zoledronic acid enhanced the cytostatic effect of cisplatin. Zoledronic acid did not induce significant apoptosis. In xenograft model, zoledronic acid significantly reduced the weight of wild type KRAS-EGFR-expressing xenograft tumor by decreasing the proliferative capacity. Futhermore, zoledronic acid induced VEGF expression and improved in vivo tumor vascularization.

Materials and methods

Membrane association of K-Ras was examined by Western-blot. In vitro cell viability, apoptotic cell death and migration were measured in NSCLC lines with different molecular background. The in vivo effect of zoledronic acid was investigated in a SCID mouse subcutaneous xenograft model.

Conclusions

The in vitro and in vivo inhibitory effect of zoledronic acid was based on the blockade of cell cycle in wild type KRAS-expressing human NSCLC cells. The zoledronic acid induced vascularization supported in vivo cytostatic effect. Our preclinical investigation suggests that patients with wild type KRAS-expressing NSCLC could potentially benefit from aminobisphosphonate therapy.

Mechanically-Loaded Breast Cancer Cells Modify Osteocyte Mechanosensitivity by Secreting Factors That Increase Osteocyte Dendrite Formation and Downstream Resorption

Advanced breast cancer predominantly metastasizes to the skeleton, at which point patient prognosis significantly declines concomitant with bone loss, pain, and heightened fracture risk. Given the skeleton's sensitivity to mechanical signals, increased mechanical loading is well-documented to increase bone mass, and it also inhibited bone metastatic tumor formation and progression in vivo, though the underlying mechanisms remain under investigation. Here, we focus on the role of the osteocyte because it is the primary skeletal mechanosensor and in turn directs the remodeling balance between formation and resoprtion. In particular, osteocytic dendrites are important for mechanosensing, but how this function is altered during bone metastatic breast cancer is unknown. To examine how breast cancer cells modulate dendrite formation and function, we exposed osteocytes (MLO-Y4) to medium conditioned by breast cancer cells (MDA-MB231) and to applied fluid flow (2 h per day for 3 days, shear stress 1.1 Pa). When loading was applied to MLOs, dendrite formation increased despite the presence of tumor-derived factors while overall MLO cell number was reduced. We then exposed MLOs to fluid flow as well as media conditioned by MDAs that had been similarly loaded. When nonloaded MLOs were treated with conditioned media from loaded MDAs, their dendrite formation increased in a manner similar to that observed due to loading alone. When MLOs simultaneously underwent loading and treatment with loaded conditioned media, dendrite formation was greatest. To understand potential molecular mechanisms, we then investigated expression of genes related to osteocyte maturation and dendrite formation (E11) and remodeling (RANKL, OPG) as well as osteocyte apoptosis. E11 expression increased with loading, consistent with increased dendrite formation. Though loaded conditioned media decreased MLO cell number, apoptosis was not detected via TUNEL staining, suggesting an inhibition of growth instead. OPG expression was inhibited while RANKL expression was unaffected, leading to an overall increase in the RANKL/OPG ratio with conditioned media from loaded breast cancer cells. Taken together, our results suggest that skeletal mechanical loading stimulates breast cancer cells to alter osteocyte mechanosensing by increasing dendrite formation and downstream resorption.

Noninvasive Imaging of CD206-Positive M2 Macrophages as an Early Biomarker for Post-Chemotherapy Tumor Relapse and Lymph Node Metastasis

Tumor relapse after initial regression post-chemotherapy is a major challenge in cancer treatment, as it usually leads to local-regional recurrence or inoperable distant metastasis. M2 macrophages diminish the tumor-inhibitory effect of chemotherapy and correlate with distant metastasis and poor prognosis. In this study, we investigated whether molecular imaging of M2 macrophages could serve as an early biomarker for tumor relapse after chemotherapy and tumor lymph node metastasis in preclinical mouse models. Methods: We developed M2 macrophage-targeted probes for near-infrared fluorescence (NIRF) imaging and single-photon emission computed tomography (SPECT) using an anti-CD206 monoclonal antibody. The specific targeting capacity and potential applications of the NIRF and SPECT probes were investigated in subcutaneous tumor and lymph node metastasis models of 4T1 murine breast cancer. Results: M2 macrophage infiltration was significantly increased in the 4T1 tumors that later underwent relapse but not in non-relapsing 4T1 tumors after cyclophosphamide treatment. Through NIRF imaging and SPECT using our synthesized probes, the infiltration of M2 macrophages in relapsing tumors and tumor lymph node metastasis could be sensitively detected. Importantly, early prediction of tumor relapse by molecular imaging of M2 macrophages resulted in an effective eradication of tumors upon combination with additional radiotherapy. Conclusion: Our findings demonstrate that M2 macrophage-targeted imaging allows for noninvasively predicting post-chemotherapy tumor relapse and sensitively detecting the metastatic lymph nodes in vivo. This imaging strategy could provide a better understanding of cancer progression, enable early prediction of tumor resistance, and have implications on the rational design of cancer therapeutics.

Nephronectin is Decreased in Metastatic Breast Carcinoma and Related to Metastatic Organs

Breast cancer causes death mostly due to distant metastasis. During metastasis, cancer cells create new conditions in which normal tissue structure can be disturbed. Nephronectin, which is the primary ligand for α8β1 integrin, plays an important role in kidney development. There are conflicting findings regarding its role in cancer progression and metastasis, especially in breast carcinoma. The aim of this study was to determine changes in nephronectin expression in primary tumor tissues and metastatic visceral organs, using metastatic and non-metastatic cell lines in a mouse model of breast cancer. In our study, 4T1-Liver Metastatic and 4T1-Heart Metastatic cells, originally derived from 4T1-murine breast carcinoma, and non-metastatic 67NR carcinoma cells were used. Cancer cells were injected orthotopically into the mammary gland of 8-10 week-old Balb-c mice. Primary tumors, lung, liver tissues were collected on 12th and 25th days after the tumor injection. Immunohistochemistry was used to determine expression of nephronectin in tissues. We also investigated the expression levels of the protein by using western blot technique. We found that lung and liver tissue of control animals (not-injected with tumor cells) expressed nephronectin which was lost in animals bearing metastatic tumor for 25 days. In accordance, nephronectin staining of lung and liver was preserved in animals injected with non-metastatic 67NR tumors. These results demonstrate that loss of nephronectin may play an important role in formation metastatic milieu for cancer cells. This is the first study demonstrating that tumor-induced loss of nephronectin expression in visceral organs in which metastatic growth takes place.

Renal Impairment Hampers Bisphosphonate Treatment in a Quarter of Lung Cancer Patients with Bone Metastasis

Renal function impairment in lung cancer patients with bone metastases was investigated, as this can limit the application of bisphosphonates representing the gold standard in the management of such cases. Clinicopathological data of 570 lung cancer patients were retrospectively analysed for changes in renal function parameters. Comorbidities included hypertension (50%), COPD (33%) and diabetes mellitus (15%). Statistical analysis was performed with Fisher's exact tests and a Cox proportional hazards model. In patients suffering from hypertension, both median serum creatinine and blood urea nitrogen (BUN) were higher (81.9 versus 75.8 μmol/L, p < 0.001 and 6.0 versus 5.7 mmol/L, p = 0.005, respectively). Such a difference could not be observed in patients with diabetes. In patients with COPD, only serum creatinine was higher (81.1 versus 77.3 μmol/L, p = 0.004). In the whole cohort, we found that while at the time of lung cancer diagnosis the ratio of patients in the pathological range (PRR) was 8.67% for serum creatinine (median: 75 μmol/L) and 14.16% for BUN (median: 5.4 mmol/L), at the time of bone metastasis the PRR for serum creatinine increased to 16.11% (median: 77.0 μmol/L) and for BUN to 24.07% (median: 6.0 mmol/L), which is a significant increase for both parameters (p < 0.001). For the whole cohort, the last laboratory results showed a 26.37% PRR for serum creatinine and 45.66% PRR for BUN (significant increase for both, p < 0.001). Multivariate analysis revealed that patients with hypertension had a higher chance for switching to the pathological range sooner (p = 0.033, HR: 1.372, CI: 1.025-1.835). Also, the appearance of the bone metastasis correlated with an acceleration of the onset of such a switch (p < 0.001, HR: 2.655, CI: 1.581-4.456). Our results suggest that renal function is impaired in a significant proportion of patients with lung cancer and highlight the importance of non-nephrotoxic drug in the management of bone metastases.

Cytotoxic effects of zoledronic acid-loaded hydroxyapatite and bone cement in malignant tumors

Metastatic and primary bone tumors are malignant tumors affecting the skeleton. Although the prognosis of patients with these tumors has improved with the development of effective chemotherapy, the challenges of local recurrence, subsequent osteolysis, degradation of bone strength and unresectable tumors persist. Local control of these tumors is therefore a key strategy to address these limitations. The third-generation bisphosphonate (BP), zoledronic acid (ZOL), has been demonstrated to reduce osteoclasts and exhibited potent antitumor effects in a number of malignancies. Hydroxyapatite (HA) and polymethyl methacrylate (PMMA) bone cement are used in orthopedic surgery as bone graft substitutes, for implant arthroplasty and bone strengthening, and as a sustained-release system for drugs such as antibiotics. At present, the antitumor effects of ZOL-loaded HA in vitro or in vivo or of ZOL-loaded bone cement in vivo have not been described. Therefore, the present study assessed the effects of ZOL-loaded HA and bone cement in malignant tumor cells. The two materials exerted strong antitumor effects against osteosarcoma, fibrosarcoma, synovial sarcoma, renal cancer, prostate cancer and lung cancer cells upon releasing ZOL. The antitumor effects of ZOL-loaded HA were less potent compared with those of ZOL-loaded bone cement, possibly as BPs exhibit higher affinity to HA. ZOL-loaded bone cement also exerted antitumor effects against pulmonary metastases and primary lesions, without exhibiting systemic toxicity in vivo. These results demonstrate that these materials may be beneficial for the treatment of malignant bone tumors, including metastatic bone tumors. In addition, as these materials are already in clinical use, such applications may be easily implemented.

Experimental and Computational Evidence on the Interaction of Cycloalkyl α-Aminobisphosphonates with Calf Thymus DNA

Fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, circular dichroism spectroscopy, viscometry, cyclic voltammetry, and differential pulse voltammetry were applied to investigate the competitive interaction of DNA with the three new cycloalkyl α-aminobisphosphonates (D₁-D₃) and spectroscopic probe, neutral red dye, and Hoechst (HO), in a Tris-hydrogen chloride buffer (pH 7.4). The spectroscopic and voltammetric studies showed that the groove binding mode of interaction is predominant in the solution containing DNA and α-aminobisphosphonates. Furthermore, the results indicated that α-aminobisphosphonate with the lengthy N alkyl chains and larger heterocyclic ring size had a stronger interaction. The principal component analysis and theoretical quantum mechanical and molecular mechanics (QM-DFT B3LYP/6-31+G* and MM-SYBYL) methods were also applied to determine the number of chemical components presented in complexation equilibrium and identify the structure complexes of DNA with the three new cycloalkyl α-aminobisphosphonates (D₁-D₃), respectively.

A Pilot Trial Evaluating Zoledronic Acid Induced Changes in [18F]FMAU-Positron Emission Tomography Imaging of Bone Metastases in Prostate Cancer

PURPOSE

We conducted a pilot trial utilizing [¹⁸F]FMAU [1-(2'-deoxy-2'-[¹⁸F]fluoro-β-D-arabinofuranosyl thymine] as a tumor tracer in positron emission tomography (PET) and evaluated its reproducibility, and changes in maximum and peak standardized uptake value (SUVmax and SUVpeak) with zoledronic acid treatment in castrate resistant prostate cancer (CRPC) patients with bone metastases (BM).

PROCEDURES

Eligible patients had CRPC with radiographic evidence of BM and creatinine clearance >30 ml/min. Two baseline [¹⁸F]FMAU-PET scans (about 1 week apart, range 2-12 days) were obtained for testing reproducibility. Zoledronic acid 4 mg was infused over 15 min within 1 week after second scan and a third PET scan was obtained 7 days later. The bony lesion with the highest uptake on the first scan was compared with later scans. Bone turnover markers and prostate-specific antigen (PSA) were obtained pre- and post-therapy. PET response was defined as decline in SUVmean of ≥15 % after zoledronic acid.

RESULTS

Eleven patients were evaluated, median age was 65 years, five were African-American and six were Caucasian, and median PSA level was 36.3 ng/ml (range 1.0-1209.3). Notably, the range of absolute percent SUVmax changes varied between 0.77 and 54.7, and only nine measurements were greater than one (1.09-2.19). Zoledronic acid did not appreciably change FMAU uptake. No clinical response was noted. Urine N-telopeptide (NTx) was markedly decreased in all patients after zoledronic acid and serum bone-specific alkaline phosphatase (BSAP) registered a modest change. Urine NTx correlated more closely with SUV max than serum BSAP.

CONCLUSIONS

FMAU tracer was able to detect bone metastases in CRPC patients but uptake was highly variable in bony lesions. Zoledronic acid did not produce an appreciable change in scans. Future investigations of FMAU tracer as a marker of early response in CRPC is recommended.

Theoretical and Instrumental Studies of the Competitive Interaction Between Aromatic α-Aminobisphosphonates with DNA Using Binding Probes

Fluorescence spectroscopy, UV-visible absorption spectroscopy, circular dichroism (CD) spectroscopy, viscometry, cyclic voltammetry (CV), and differential pulse voltammetry (DPV) were applied to investigate the competitive interaction of DNA with two aromatic α-aminobisphosphonates and neutral red dye (NR, intercalator) and Hoechst (Ho, groove binder) as spectroscopic probes, in a Tris-hydrogen chloride buffer solution (pH 7.4). The principal component analysis (PCA) was applied to determine the number of chemical components presented in complexation equilibrium of DNA with the aromatic α-aminobisphosphonates (B₁ and B₂). The spectroscopic and voltammetric studies showed that the groove binding mode of interaction is predominant in the solution containing DNA and α-aminobisphosphonates. Furthermore, the results indicated that α-aminobisphosphonate with the lengthy N-alkyl chains had a stronger interaction. The PCA and theoretical quantum mechanical and molecular mechanic methods were also utilized to determine the structure of DNA with the two α-aminobisphosphonates (B₁ and B₂).

Oral Bisphosphonates and Improved Survival of Breast Cancer

Purpose: Bisphosphonates are used for treatment or prevention of osteoporosis and of bone metastases. The use of oral bisphosphonates was suggested to be associated with reduced risk of developing breast cancer, and their positive influence on breast cancer survival was only demonstrated with third-generation bisphosphonates. We studied the association of use of oral bisphosphonates after breast cancer diagnosis on overall and breast cancer survival.Experimental Design: A nested case-control analysis was performed using data from the population-based Breast Cancer in Northern Israel Study (BCINIS). Participants were postmenopausal women with newly diagnosed breast cancer insured by Clalit. Use of second-generation bisphosphonates (alendronate and/or risedronate) was identified using computerized prescription records. The analysis was restricted to women who did not use bisphosphonates prior to diagnosis.Results: In a cohort of 3,731 postmenopausal women with breast cancer, followed up for an average of 70 months, there were 799 cases of death which were matched to 15,915 control periods of living breast cancer cases. Use of bisphosphonates after diagnosis for at least 18 months was significantly more common among survivors than among their matched controls who died, adjusted for tumor stage/grade (overall survival: OR = 0.63, 0.41-0.96, P = 0.03; breast cancer-specific survival: OR = 0.28, 0.09-0.91, P = 0.035). A similar advantageous effect, but statistically underpowered, was found in estrogen receptor (ER)-positive, ER-negative, and HER2neu-positive tumors.Conclusions: The use of oral bisphosphonates, by postmenopausal, probably osteoporotic, women initiated after diagnosis of breast cancer was associated with a significant improvement in overall and breast-specific odds of survival. Clin Cancer Res; 23(7); 1684-9. ©2016 AACR.

Pamidronate Down-regulates Tumor Necrosis Factor-alpha Induced Matrix Metalloproteinases Expression in Human Intervertebral Disc Cells

Background

N-containing bisphosphonates (BPs), such as pamidronate and risedronate, can inhibit osteoclastic function and reduce osteoclast number by inducing apoptotic cell death in osteoclasts. The aim of this study is to demonstrate the effect of pamidronate, second generation nitrogen-containing BPs and to elucidate matrix metallo-proteinases (MMPs) mRNA expression under serum starvation and/or tumor necrosis factor alpha (TNF-α) stimulation on metabolism of intervertebral disc (IVD) cells in vitro.

Methods

Firstly, to test the effect of pamidronate on IVD cells in vitro, various concentrations (10^-12, 10^-10, 10^-8, and 10^-6 M) of pamidronate were administered to IVD cells. Then DNA and proteoglycan synthesis were measured and messenger RNA (mRNA) expressions of type I collagen, type II collagen, and aggrecan were analyzed. Secondly, to elucidate the expression of MMPs mRNA in human IVD cells under the lower serum status, IVD cells were cultivated in full serum or 1% serum. Thirdly, to elucidate the expression of MMPs mRNA in IVD cells under the stimulation of 1% serum and TNF-α (10 ng/mL) In this study, IVD cells were cultivated in three dimensional alginate bead.

Results

Under the lower serum culture, IVD cells in alginate beads showed upregulation of MMP 2, 3, 9, 13 mRNA. The cells in lower serum and TNF-α also demonstrated upregulation of MMP-2, 3, 9, and 13 mRNA. The cells with various doses of pamidronate and lower serum and TNF-α were reveled partial down-regulation of MMPs.

Conclusions

Pamidronate, N-containing second generation BPs, was safe in metabolism of IVD in vitro maintaining chondrogenic phenotype and matrix synthesis, and down-regulated TNF-α induced MMPs expression.

Three-Dimensional Mechanical Loading Modulates the Osteogenic Response of Mesenchymal Stem Cells to Tumor-Derived Soluble Signals

Dynamic mechanical loading is a strong anabolic signal in the skeleton, increasing osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BM-MSCs) and increasing the bone-forming activity of osteoblasts, but its role in bone metastatic cancer is relatively unknown. In this study, we integrated a hydroxyapatite-containing three-dimensional (3D) scaffold platform with controlled mechanical stimulation to investigate the effects of cyclic compression on the interplay between breast cancer cells and BM-MSCs as it pertains to bone metastasis. BM-MSCs cultured within mineral-containing 3D poly(lactide-co-glycolide) (PLG) scaffolds differentiated into mature osteoblasts, and exposure to tumor-derived soluble factors promoted this process. When BM-MSCs undergoing osteogenic differentiation were exposed to conditioned media collected from mechanically loaded breast cancer cells, their gene expression of osteopontin was increased. This was further enhanced when mechanical compression was simultaneously applied to BM-MSCs, leading to more uniformly deposited osteopontin within scaffold pores. These results suggest that mechanical loading of 3D scaffold-based culture models may be utilized to evaluate the role of physiologically relevant physical cues on bone metastatic breast cancer. Furthermore, our data imply that cyclic mechanical stimuli within the bone microenvironment modulate interactions between tumor cells and BM-MSCs that are relevant to bone metastasis.

Osteolytica: An automated image analysis software package that rapidly measures cancer-induced osteolytic lesions in in vivo models with greater reproducibility compared to other commonly used methods

Methods currently used to analyse osteolytic lesions caused by malignancies such as multiple myeloma and metastatic breast cancer vary from basic 2-D X-ray analysis to 2-D images of micro-CT datasets analysed with non-specialised image software such as ImageJ. However, these methods have significant limitations. They do not capture 3-D data, they are time-consuming and they often suffer from inter-user variability. We therefore sought to develop a rapid and reproducible method to analyse 3-D osteolytic lesions in mice with cancer-induced bone disease. To this end, we have developed Osteolytica, an image analysis software method featuring an easy to use, step-by-step interface to measure lytic bone lesions. Osteolytica utilises novel graphics card acceleration (parallel computing) and 3-D rendering to provide rapid reconstruction and analysis of osteolytic lesions. To evaluate the use of Osteolytica we analysed tibial micro-CT datasets from murine models of cancer-induced bone disease and compared the results to those obtained using a standard ImageJ analysis method. Firstly, to assess inter-user variability we deployed four independent researchers to analyse tibial datasets from the U266-NSG murine model of myeloma. Using ImageJ, inter-user variability between the bones was substantial (±19.6%), in contrast to using Osteolytica, which demonstrated minimal variability (±0.5%). Secondly, tibial datasets from U266-bearing NSG mice or BALB/c mice injected with the metastatic breast cancer cell line 4T1 were compared to tibial datasets from aged and sex-matched non-tumour control mice. Analyses by both Osteolytica and ImageJ showed significant increases in bone lesion area in tumour-bearing mice compared to control mice. These results confirm that Osteolytica performs as well as the current 2-D ImageJ osteolytic lesion analysis method. However, Osteolytica is advantageous in that it analyses over the entirety of the bone volume (as opposed to selected 2-D images), it is a more rapid method and it has less user variability.

Oxidative stress plays an important role in zoledronic acid-induced autophagy

Several pre-clinical and clinical studies have demonstrated zoledronic acid (Zol), which regulates the mevalonate pathway, has efficient anti-cancer effects. Zol can also induce autophagy. The aim of this study is to add new understanding to the mechanism of autophagy induction by Zol. LC3B-II, the marker for autophagy was increased by Zol treatment in breast cancer cells. Autophagosomes induced by Zol were visualized and quantified in both transient (pDendra2-hLC3) and stable MCF-7-GFP-LC3 cell lines. Acidic vesicular organelles were quantified using acridine orange. Zol induced a dose and time dependent autophagy. Treatment of Zol increased oxidative stress in MCF-7 cells, which was reversed by GGOH or anti-oxidants. On the other hand, treatment with GGOH or anti-oxidants resulted in decreased levels of LC3B-II. Further, the induced autophagy was irreversible, as the washout of Zol after 2 h or 24 h resulted in similar levels of autophagy, as induced by continuous treatment after 72 h. Thus, it can be summarized that Zol can induce a dose dependent but irreversible autophagy, by its effect on the mevalonate pathway and oxidative stress. This study adds to the understanding of the mechanism of action of Zol, and that it can induce autophagy at clinically relevant shorter exposure times in cancer cells.

In vitro and in vivo toxicity of 5-FdU-alendronate, a novel cytotoxic bone-seeking duplex drug against bone metastasis

BACKGROUND

Bone remains one of the most common anatomic sites for cancer metastases, and the limited therapeutic options aggravate cancer-related morbidity and mortality in multiple malignancies. The covalent conjugation of the amino-bisphosphonate alendronate (ale) with the antimetabolite 5-fluoro-2'-desoxyuridine (5-FdU) results in N(4)-(butyl-(4-hydroxy-4-phosphono)phosphate)-5-fluoro-2'-desoxyuridine (5-FdU-alendronat, 5-FdU-ale), an effective, novel bone-targeting duplex drug directed against skeletal cancer manifestations.

METHODS

In vitro cytotoxicity of ale, 5-FdU or 5-FdU-ale was measured with Alamar Blue and MUH cell viability assays in 14 malignant melanoma, multiple myeloma, bone marrow-derived stromal cell and osteoblast-like cell lines. In vivo toxicity was evaluated using the chicken embryo assay and evaluation of nephrotoxicity and the systemic toxicity in Balb/c nude mice. The effect of 5-FdU-ale on osteoclast was evaluated with Balb/c nude mice in a metastatic breast cancer mouse model.

RESULTS

A cell line-specific, dose-related cytotoxicity was observed for 5-FdU-ale in all cancer cell lines tested, which was significantly less toxic than 5-FdU alone when compared to the benign osteoblasts or stromal cells. The embryotoxicity of 5-FdU-ale was significantly less than that of the parental drugs alendronate or 5-FdU. 5-FdU-ale showed no signs of unwanted side effects, weight loss or nephrotoxicity in mice. In a bone metastasis mouse model, 5-FdU-ale reduced the number of tumor-associated osteoclasts.

CONCLUSION

The coupling of an amino-bisphosphonate with an antimetabolite via an N-alkyl-bonding offers a new strategy for the preparation of amino-bisphosphonates conjugates with a cancer cell-specific, efficacious cytotoxic bone-targeting potential along with a reduced systemic toxicity. The innovative duplex drug 5-FdU-ale therefore warrants further clinical investigation.