Drug resistance and physiological roles of RND multidrug efflux pumps in Salmonella enterica, Escherichia coli and Pseudomonas aeruginosa

Drug efflux pumps transport antimicrobial agents out of bacteria, thereby reducing the intracellular antimicrobial concentration, which is associated with intrinsic and acquired bacterial resistance to these antimicrobials. As genome analysis has advanced, many drug efflux pump genes have been detected in the genomes of bacterial species. In addition to drug resistance, these pumps are involved in various essential physiological functions, such as bacterial adaptation to hostile environments, toxin and metabolite efflux, biofilm formation and quorum sensing. In Gram-negative bacteria, efflux pumps in the resistance–nodulation–division (RND) superfamily play a clinically important role. In this review, we focus on Gram-negative bacteria, including Salmonella enterica , Escherichia coli and Pseudomonas aeruginosa , and discuss the role of RND efflux pumps in drug resistance and physiological functions.

Non-clinical, quality and environmental impact assessments of cell and gene therapy products: Report on the 5th Asia Partnership Conference of Regenerative Medicine - April 7, 2022

The 5th Asia Partnership Conference of Regenerative Medicine (APACRM) was held online on April 7, 2022 to promote regulatory harmonization of regenerative medicine products throughout Asia. The recognition of domestic regulatory guidelines within each country and region and the underpinning rationales are important initial steps toward the harmonization of regulations. The 5th APACRM featured open dialog regarding non-clinical, quality and environmental impact assessment settings for cell and gene therapy products through presentations from the industry and panel discussions with regulatory agencies. The latest updates on regenerative medicine fields in each country and region were also introduced. This paper summarizes the proceedings of the 5th APACRM for public dissemination to foster future discussion.

[Pharmacological and clinical profile of asciminib hydrochloride, a novel first-in-class tyrosine kinase inhibitor specifically targeting ABL myristoyl pocket]

On March 28th, 2022, asciminib hydrochloride (Scemblix® Tablets 20 ‍mg/40 ‍mg), the world's first tyrosine kinase inhibitor (TKI) specifically targeting the ABL myristoyl pocket (STAMP inhibitor), was approved for chronic myeloid leukemia (CML) resistant or intolerant to prior therapy. Asciminib specifically binds to the myristoyl pocket, an allosteric site of BCR::ABL1, and inhibits the ABL1 family molecules. In vitro and in vivo pharmacology studies demonstrated cell growth inhibition and antitumor effects of asciminib. The international phase I study for patients with chronic or accelerated phase CML investigated the maximum tolerated dose (MTD) and recommended dose for expansion (RDE) of asciminib monotherapy. However, the MTD was not reached, so and RDE was determined based on tolerability, safety, pharmacokinetics (PK) and preliminary efficacy data obtained by the time of the study. RDE was determined to be 40 ‍mg twice daily in chronic or accelerated phase CML without T315I mutation, and 200 ‍mg twice daily in chronic or accelerated phase CML with T315I mutation. The international phase III study for patients with chronic phase CML who were previously treated with ≥2 TKIs and resistant or intolerant to the recent treatment demonstrated the superiority of asciminib over bosutinib in achieving the primary endpoint of a major molecular response (MMR) at week 24. Regarding safety, the most common treatment-related adverse event in asciminib arm was thrombocytopenia, and others included neutropenia. Asciminib is expected to be a new treatment option for CML patients who have limited choices due to resistance or intolerance to previous therapies.

Investigating multidrug efflux pumps associated with fatty acid salt resistance in Escherichia coli

Fatty acids salts exert bactericidal and bacteriostatic effects that inhibit bacterial growth and survival. However, bacteria can overcome these effects and adapt to their environment. Bacterial efflux systems are associated with resistance to different toxic compounds. Here, several bacterial efflux systems were examined to determine their influence on fatty acid salt resistance in Escherichia coli. Both acrAB and tolC E. coli deletion strains were susceptible to fatty acid salts, while plasmids carrying acrAB, acrEF, mdtABC, or emrAB conferred drug resistance to the ΔacrAB mutant, which indicated complementary roles for these multidrug efflux pumps. Our data exemplify the importance of bacterial efflux systems in E. coli resistance to fatty acid salts.

Analysis of multidrug efflux transporters in resistance to fatty acid salts reveals a TolC-independent function of EmrAB in Salmonella enterica

Fatty acids salts exhibit bacteriostatic and bactericidal effects to inhibit bacterial growth and survival. Bacteria adapt to their environment to overcome these antibacterial effects through undefined mechanisms. In Gram-negative bacteria, drug efflux systems are associated with resistance to various substances. Studies have identified multiple drug efflux systems in Salmonella enterica. The aim of this study was to investigate whether drug efflux systems contribute to fatty acid salts resistance in S. enterica. We used deletion and overexpressing strains of S. enterica for drug efflux transporters. Susceptibility to fatty acid salts was determined by measuring minimum inhibitory concentrations and performing growth assays. Our findings revealed that acrAB, acrEF, emrAB and tolC in S. enterica contribute resistance to fatty acid salts. Furthermore, EmrAB, which is known to function with TolC, contributes to the fatty acid salts resistance of S. enterica in a TolC-independent manner. This study revealed that drug efflux systems confer fatty acid satls resistance to S. enterica. Notably, although EmrAB is normally associated with antimicrobial resistance in a TolC-dependent manner, it was found to be involved in fatty acid salts resistance in a TolC-independent manner, indicating that the utilization of TolC by EmrAB is substrate dependent in S. enterica.

[Pharmacological and clinical profile of Onasemnogene Aveparvovec, the first gene therapy for spinal muscular atrophy (SMA)]

Onasemnogene abeparvovec (Zolgensma^®; formerly AVXS-101) is a one-time gene therapy designed to address the genetic root cause of spinal muscular atrophy (SMA) by replacing the function of the missing or nonworking SMN1 gene via an adeno-associated AAV9 viral vector. On March 19, 2020, the Japanese Ministry of Health, Labor and Welfare approved onasemnogene abeparvovec for the treatment of SMA patients <2 years of age, including presymptomatic patients with a genetic diagnosis. Patients must be negative for elevated anti-AAV9 antibodies. Onasemnogene abeparvovec is administered through a single intravenous infusion, delivering a new working copy of the SMN gene into a patient's cells. Intravenous administration of onasemnogene abeparvovec to SMA model mice resulted in sustained expression of survival motor neuron (SMN) protein, weight gain, improvement of motor function, and prolongation of survival. Its clinical efficacy and safety have been demonstrated through the Phase I START and Phase III STR1VE-US, STR1VE-EU, and SPR1NT trials, and their long-term extension studies. SMA and presymptomatic patients treated with onasemnogene abeparvovec have achieved rates of survival not observed in the natural history of SMA. Treatment has led to rapid motor function improvement, often within one month of dosing, and developmental milestone achievement, including the ability to sit without support. The most commonly observed adverse effects after treatment were elevated liver enzymes, which often resolved with a course of prednisolone, and vomiting. This review discusses the rationale underlying gene replacement therapy for SMA, and describes the basic science, clinical trial experience, and use of onasemnogene abeparvovec.

Early detection of exacerbation of the severe acute respiratory syndrome coronavirus 2 infection using Fitbit (DEXTERITY pilot study)

 

Some patients with coronavirus disease 2019 (COVID-19) experienced sudden death because of sudden symptom deterioration. Thus, an alarm system that could detect early signs of COVID-19 exacerbation beforehand, to prevent serious illness or death of patients while receiving outpatient treatment at home or in hotels is necessary. Here, we tested whether estimated oxygen variations (EOV), a relative physiological scale that represents users' blood oxygen saturation level during sleep measured by Fitbit, predicted COVID-19 symptom exacerbation. Study period was from August to November 2020. We enrolled 23 COVID-19 patients diagnosed by SARS-CoV-2 polymerase chain reaction-positive (mean age ± standard deviation, 50.9±20 years; 70% female), let each patient wore the Fitbit for 30 days; COVID-19 symptoms were exacerbated in 6 (26%). High EOV signal (a patient's oxygen level exhibits significant dip and recovery within the index period) had 80% sensitivity before symptom exacerbations, whereas resting heart rate signal only had 50% sensitivity. Coincidental obstructive sleep apnea syndrome confirmed by polysomnography was detected in a patient by consistently high EOV signals. This pilot study successfully detected early COVID-19 symptoms exacerbation by measuring EOV and may help to identify early signs of COVID-19 exacerbation.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): The investigational device used in this study, Fitbit Charge 3, was provided by Fitbit Japan. Summary of high EOV signals and eventsThe clinical course of COVID-19

Non-clinical assessment of cell therapy products: the perspective from five Asian countries/regions based on regulatory guidelines and the underpinning rationales

BACKGROUND AIMS

Cell-based regenerative medicine is an innovative field that can potentially alter the overall survival and quality of life of patients with devastating diseases. Several cell therapy products (CTPs) have been approved within the last two decades, and more are under development. The establishment of an effective developmental strategy in accordance with the regulatory bodies of each country/region is crucial for fast delivery of each respective CTP. In particular, facilitating investigational new drug (IND) approval is important for accelerating the transition from non-clinical to clinical research/trial phases.

METHODS

Here the authors compared the non-clinical prerequisites for initiating clinical studies in five Asian countries/regions (India, China, Korea, Taiwan and Japan) from an industry viewpoint. The authors first identified the differences and tried to clarify the perspectives/considerations underpinning the different requirements.

RESULTS

The authors' findings revealed that differences in regulations and development experiences, especially with CTPs, have led to clear differences in the non-clinical study package and its corresponding study design.

CONCLUSIONS

By sharing experiences of the research and development of CTPs among Asian countries/regions and including not only industry but also regulatory authorities, we will be able to expedite cross-border IND approval and eventually contribute to the early delivery of innovative CTPs to many Asian patients.

Signal Change of Acute Cortical and Juxtacortical Microinfarction on Follow-Up MRI

BACKGROUND AND PURPOSE

Although the clinical importance of cortical microinfarcts has become well-recognized recently, the evolution of cortical microinfarcts on MR imaging is not fully understood. The aim of this study was to examine the temporal changes in acute cortical microinfarcts using susceptibility-weighted imaging and conventional MR imaging.

MATERIALS AND METHODS

Patients with acute infarcts located in the cortical and/or juxtacortical region measuring ≤10 mm in axial diameter based on diffusion-weighted imaging who had a follow-up 3T MR imaging were retrospectively included in the study. All lesions did not show hypointensity on initial T2*WI. For cortical and/or juxtacortical microinfarcts detected on initial DWI, 2 neuroradiologists evaluated the follow-up MR imaging (T2WI, FLAIR, T2*WI, and SWI) and assessed lesion signal intensities and locations (cortical microinfarcts or microinfarcts with juxtacortical white matter involvement).

RESULTS

On initial DWI, 2 radiologists observed 180 cortical and/or juxtacortical microinfarcts in 35 MR imaging examinations in 25 patients; on follow-up, the neuroradiologists identified 29 cortical microinfarcts (16%) on T2WI, 9 (5%) on FLAIR, 4 (2%) on T2*, and 97 (54%) on SWI. All cortical microinfarcts detected with any follow-up MR imaging showed hyperintensity on T2WI/FLAIR and/or hypointensity on T2*WI and SWI.

CONCLUSIONS

SWI revealed conversion (paramagnetic susceptibility changes) of acute cortical microinfarcts, suggesting that a substantial number of cortical microinfarcts may contain hemorrhagic components.

One-hour plasma glucose as a predictor of the development of Type 2 diabetes in Japanese adults

AIMS

To test the hypothesis that 1-h plasma glucose in an oral glucose tolerance test is a better predictor of the development of diabetes than 2-h plasma glucose, independently of indices of insulin secretion or action in Japanese adults.

METHODS

A historical cohort study was conducted in 1445 Japanese workers who did not have diabetes. The association between 1-h plasma glucose and the development of Type 2 diabetes was analysed.

RESULTS

Overall, 95 of the study participants developed Type 2 diabetes during a mean follow-up of 4.5 years. The area under the receiver-operating characteristic curve for 1-h plasma glucose for future diabetes [0.88 (95% CI 0.84-0.91)] was greater than that for 2-h plasma glucose [0.79 (95% CI 0.74-0.84)], and for insulinogenic [0.73 (95% CI 0.68-0.78)] and disposition indices [0.79 (95% CI 0.74-0.84); P < 0.05]. Compared with the first quartile, the hazard ratio for future diabetes in the fourth quartile of 1-h plasma glucose was 42.5 [95% CI 5.7-315.2 (P < 0.05)] and the hazard ratio in the fourth quartile of 2-h plasma glucose was 4.4 [95% CI 1.8-10.8 (P < 0.05)], after adjustments for covariates including fasting plasma glucose. The significance of the elevated hazard ratio in the fourth quartile of 1-h plasma glucose was maintained after adjustments for 2-h plasma glucose, insulinogenic index or disposition index, whereas the elevation of the hazard ratio in the fourth quartile of 2-h plasma glucose was diminished and was no longer significant after adjustments for 1-h plasma glucose.

CONCLUSIONS

One-hour plasma glucose had a greater association with the future development of Type 2 diabetes than did 2-h plasma glucose, independently of oral glucose tolerance test-derived indices of insulin action in a Japanese population.

Lateral Asymmetry and Spatial Difference of Iron Deposition in the Substantia Nigra of Patients with Parkinson Disease Measured with Quantitative Susceptibility Mapping

BACKGROUND AND PURPOSE

Quantitative susceptibility mapping is useful for assessing iron deposition in the substantia nigra of patients with Parkinson disease. We aimed to determine whether quantitative susceptibility mapping is useful for assessing the lateral asymmetry and spatial difference in iron deposits in the substantia nigra of patients with Parkinson disease.

MATERIALS AND METHODS

Our study population comprised 24 patients with Parkinson disease and 24 age- and sex-matched healthy controls. They underwent 3T MR imaging by using a 3D multiecho gradient-echo sequence. On reconstructed quantitative susceptibility mapping, we measured the susceptibility values in the anterior, middle, and posterior parts of the substantia nigra, the whole substantia nigra, and other deep gray matter structures in both hemibrains. To identify the more and less affected hemibrains in patients with Parkinson disease, we assessed the severity of movement symptoms for each hemibrain by using the Unified Parkinson's Disease Rating Scale.

RESULTS

In the posterior substantia nigra of patients with Parkinson disease, the mean susceptibility value was significantly higher in the more than the less affected hemibrain substantia nigra (P < .05). This value was significantly higher in both the more and less affected hemibrains of patients with Parkinson disease than in controls (P < .05). Asymmetry of the mean susceptibility values was significantly greater for patients than controls (P < .05). Receiver operating characteristic analysis showed that quantitative susceptibility mapping of the posterior substantia nigra in the more affected hemibrain provided the highest power for discriminating patients with Parkinson disease from the controls.

CONCLUSIONS

Quantitative susceptibility mapping is useful for assessing the lateral asymmetry and spatial difference of iron deposition in the substantia nigra of patients with Parkinson disease.

Evidence of Notch-Hesr-Nrf2 Axis in Muscle Stem Cells, but Absence of Nrf2 Has No Effect on Their Quiescent and Undifferentiated State

Nrf2 is a master regulator of oxidative stresses through the induction of anti-oxidative genes. Nrf2 plays roles in maintaining murine hematopoietic stem cells and fly intestinal stem cells. The canonical Notch signaling pathway is also crucial for maintaining several types of adult stem cells including muscle stem cells (satellite cells). Here, we show that Dll1 induced Nrf2 expression in myogenic cells. In addition, primary targets of Notch signaling, Hesr1 and Hesr3, were involved in the up-regulation of Nrf2 mRNA and expression of its target genes. In vitro, Nrf2 had anti-myogenic and anti-proliferative effects on primary myoblasts. In vivo, although Nrf2-knockout mice showed decreased expression of its target genes in muscle stem cells, adult muscle stem cells of Nrf2-knockout mice did not exhibit the phenotype. Taken together, in muscle stem cells, the Notch-Hesr-Nrf2 axis is a pathway potentially inducing anti-oxidative genes, but muscle stem cells either do not require Nrf2-mediated anti-oxidative gene expression or they have a complementary system compensating for the loss of Nrf2.

Objective tumor response to denosumab in patients with giant cell tumor of bone: a multicenter phase II trial

A RANK ligand-specific inhibitor, denosumab, was predicted to reduce osteolysis and control disease progression in patients with giant cell tumor of bone (GCTB). We report, for the first time, the results of the response of GCTB to denosumab obtained from a prospective independent imaging assessment. The findings demonstrate that denosumab has robust clinical efficacy in the treatment of GCTB.

Background

Giant cell tumor of bone (GCTB) is a rare primary bone tumor, characterized by osteoclast-like giant cells that express receptor activator of nuclear factor-kappa B (RANK), and stromal cells that express RANK ligand (RANKL), a key mediator of osteoclast activation. A RANKL-specific inhibitor, denosumab, was predicted to reduce osteolysis and control disease progression in patients with GCTB.

Patients and methods

Seventeen patients with GCTB were enrolled. Patients were treated with denosumab at 120 mg every 4 weeks, with a loading dose of 120 mg on days 8 and 15. To evaluate efficacy, objective tumor response was evaluated prospectively by an independent imaging facility on the basis of prespecified criteria.

Results

The proportion of patients with an objective tumor response was 88% based on best response using any tumor response criteria. The proportion of patients with an objective tumor response using individual response criteria was 35% based on the modified Response Evaluation Criteria in Solid Tumors (RECIST) criteria, 82% based on the modified European Organization for Research and Treatment of Cancer (EORTC) criteria, and 71% based on inverse Choi criteria. The median time of study treatment was 13.1 months.

Conclusion

The findings demonstrate that denosumab has robust clinical efficacy in the treatment of GCTB.

Visualization of the Medial and Lateral Geniculate Nucleus on Phase Difference Enhanced Imaging

BACKGROUND AND PURPOSE

The precise identification and measurement of the medial geniculate nucleus and lateral geniculate nucleus on MR imaging remain technically challenging because the thalamic nuclei are small structures. We compared the visualization of the medial geniculate nucleus and lateral geniculate nucleus on phase difference enhanced imaging with 3D high-resolution phase imaging, 2D-T2WI, STIR, proton attenuation-weighted imaging, and DTI acquired at 3T. We also measured the volume and height of the medial geniculate nucleus and lateral geniculate nucleus on phase difference enhanced imaging.

MATERIALS AND METHODS

Phase difference enhanced, 2D-T2-weighted, STIR, proton attenuation-weighted, and DTI were acquired on a 3T MR imaging unit in 10 healthy volunteers. Two neuroradiologists recorded the qualitative visualization scores of the medial geniculate nucleus and lateral geniculate nucleus, specifically the identification of their boundaries, for all images. Measurement differences were assessed with the Wilcoxon signed rank test. The volume and height of the medial geniculate nucleus and lateral geniculate nucleus were measured on phase difference enhanced imaging and compared with previously reported values.

RESULTS

The qualitative visualization scores of the lateral geniculate nucleus and medial geniculate nucleus were significantly higher on phase difference enhanced images than on T2-weighted, proton attenuation-weighted, STIR, or DTI (P < .05). On phase difference enhanced imaging, the medial geniculate nucleus and lateral geniculate nucleus were bordered by low-intensity structures: the cerebral peduncle, the origin of the optic radiation, and the superior and inferior quadrigeminal brachia. The volume of the medial geniculate nucleus and lateral geniculate nucleus varied from 74.0 to 183.75 mm(3) (mean, 129.0 ± 34.7 mm(3)) and from 96.5 to 173.75 mm(3) (mean, 135.2 ± 28.0 mm(3)), respectively.

CONCLUSIONS

For the depiction of the medial geniculate nucleus and lateral geniculate nucleus on 3T MR imaging, phase difference enhanced imaging is superior to conventional MR imaging. The medial geniculate nucleus and lateral geniculate nucleus volumes vary among individuals.

Three-year denosumab treatment in postmenopausal Japanese women and men with osteoporosis: results from a 1-year open-label extension of the Denosumab Fracture Intervention Randomized Placebo Controlled Trial (DIRECT)

SUMMARY

A 12-month extension phase of DIRECT in Japanese subjects with osteoporosis showed that total 3 years of denosumab treatment in Japanese postmenopausal women and men with osteoporosis was associated with low fracture rates, persistent bone turnover marker (BTM) reductions, continuous bone mineral density (BMD) increases, and a favorable overall benefit/risk profile.

INTRODUCTION

The DIRECT trial demonstrated that 2 years of treatment with denosumab 60 mg subcutaneously every 6 months significantly reduced the incidence of vertebral fracture compared to placebo in Japanese postmenopausal women and men with osteoporosis. The purpose of this study is to evaluate the efficacy and safety of denosumab treatment for up to 3 years.

METHODS

This study includes a 2-year randomized, double-blind, placebo-controlled phase and a 1-year open-label extension phase in which all subjects received denosumab. The data correspond to 3 years of denosumab treatment in subjects who received denosumab (long-term group) and 1 year of denosumab treatment in subjects who received placebo (cross-over group) in the double-blind phase.

RESULTS

Eight hundred and ten subjects who completed the double-blind phase enrolled into the extension phase, and 775 subjects completed the study. All subjects received denosumab with daily supplements of calcium and vitamin D. The cumulative 36-month incidences of new or worsening vertebral fractures and new vertebral fractures were 3.8 and 2.5 %, respectively, in the long-term group. In this group, the BMD continued to increase, and the reduction in BTMs was maintained. In the cross-over group, comparable BMD increases and BTMs reductions to those of in their first year of the long-term group were confirmed. Adverse events did not show a notable increase with long-term denosumab administration. One event of osteonecrosis of the jaw occurred in the cross-over group.

CONCLUSIONS

Three-year denosumab treatment in Japanese subjects with osteoporosis showed a favorable benefit/risk profile.

Pim-2 kinase is an important target of treatment for tumor progression and bone loss in myeloma

Pim-2 kinase is overexpressed in multiple myeloma (MM) cells to enhance their growth and survival, and regarded as a novel therapeutic target in MM. However, the impact of Pim-2 inhibition on bone disease in MM remains unknown. We demonstrated here that Pim-2 expression was also upregulated in bone marrow stromal cells and MC3T3-E1 preosteoblastic cells in the presence of cytokines known as the inhibitors of osteoblastogenesis in MM, including interleukin-3 (IL-3), IL-7, tumor necrosis factor-α, transforming growth factor-β (TGF-β) and activin A, as well as MM cell conditioned media. The enforced expression of Pim-2 abrogated in vitro osteoblastogenesis by BMP-2, which suggested Pim-2 as a negative regulator for osteoblastogenesis. Treatment with Pim-2 short-interference RNA as well as the Pim inhibitor SMI-16a successfully restored osteoblastogenesis suppressed by all the above inhibitory factors and MM cells. The SMI-16a treatment potentiated BMP-2-mediated anabolic signaling while suppressing TGF-β signaling. Furthermore, treatment with the newly synthesized thiazolidine-2,4-dione congener, 12a-OH, as well as its prototypic SMI-16a effectively prevented bone destruction while suppressing MM tumor growth in MM animal models. Thus, Pim-2 may have a pivotal role in tumor progression and bone loss in MM, and Pim-2 inhibition may become an important therapeutic strategy to target the MM cell-bone marrow interaction.

Mechanisms of preferential metastasis of breast cancer to bone - (Review)

Breast cancer frequently and preferentially spreads to bone. Once breast cancer colonizes bone, it is essentially incurable. The cellular and molecular mechanisms by which breast cancer selectively metastasizes to bone remain largely unknown. Elucidation of these mechanisms should lead to the development of effective and specific therapeutic strategies for bone metastasis of breast cancer.

Anti-aging Effects of Co-enzyme Q10 on Periodontal Tissues

Oxidative stress is associated with age-related reactions. The anti-oxidative effects of a reduced form of co-enzyme Q10 (rCoQ10) suppress oxidative stress, which may contribute to the prevention of age-related inflammatory reactions. We examined the effects of topically applied rCoQ10 on periodontal inflammatory reactions in a rat aging model. Male Fischer 344 rats, 2 (n = 6) and 4 mos (n = 18) of age, were used. All of the two-month-old rats and 6 of the four-month-old rats were sacrificed and 12 remaining four-month-old rats received topically applied ointment with or without 1% rCoQ10 on the gingival surface until they reached 6 mos of age. The rats showed an age-dependent increase in circulating oxidative stress. RCoQ10 decreased oxidative DNA damage and tartrate-resistant acid-phosphatase-positive osteoclasts in the periodontal tissue at 6 mos of age as compared with the control. The same conditions lowered gene expression of caspase-1 and interleukin-1β in the periodontal tissue. Furthermore, Nod-like receptor protein 3 inflammasomes were less activated in periodontal tissues from rCoQ10-treated rats as compared with the control rats. Our results suggest that rCoQ10 suppresses age-related inflammatory reactions and osteoclast differentiation by inhibiting oxidative stress.

Protective effects of mineralocorticoid receptor blockade against neuropathy in experimental diabetic rats

AIMS

Mineralocorticoid receptor (MR) blockade is an effective treatment for hypertension and diabetic nephropathy. There are no data on the effects of MR blockade on diabetic peripheral neuropathy (DPN). The aim of this study was to determine whether MRs are present in the peripheral nerves and to investigate the effectiveness of MR blockade on DPN in streptozotocin (STZ)-induced diabetic rats.

METHODS

Expression of MR protein and messenger RNA (mRNA) was examined in the peripheral nerves using Western blot analysis and RT-PCR. We next studied the effects of the selective MR antagonist eplerenone and the angiotensin II receptor blocker candesartan on motor and sensory nerve conduction velocity (NCV), morphometric changes and cyclooxygenase-2 (COX-2) gene and NF-κB protein expression in the peripheral nerves of STZ-induced diabetic rats.

RESULTS

Expression of MR protein and mRNA in peripheral nerves was equal to that in the kidney. Motor NCV was significantly improved by 8 weeks of treatment with either eplerenone (39.1 ± 1.2 m/s) or candesartan (46.4 ± 6.8 m/s) compared with control diabetic rats (33.7 ± 2.0 m/s) (p < 0.05). Sensory NCV was also improved by treatment with candesartan or eplerenone in diabetic rats. Eplerenone and candesartan caused significant improvement in mean myelin fibre area and mean myelin area compared with control diabetic rats (p < 0.05). COX-2 mRNA and NF-κB protein were significantly elevated in the peripheral nerves of diabetic rats compared with control rats, and treatment with eplerenone or candesartan reduced these changes in gene expression (p < 0.05).

CONCLUSION

MR blockade may have neuroprotective effects on DPN.

Hesr1 and Hesr3 are essential to generate undifferentiated quiescent satellite cells and to maintain satellite cell numbers

Satellite cells, which are skeletal muscle stem cells, divide to provide new myonuclei to growing muscle fibers during postnatal development, and then are maintained in an undifferentiated quiescent state in adult skeletal muscle. This state is considered to be essential for the maintenance of satellite cells, but their molecular regulation is unknown. We show that Hesr1 (Hey1) and Hesr3 (Heyl) (which are known Notch target genes) are expressed simultaneously in skeletal muscle only in satellite cells. In Hesr1 and Hesr3 single-knockout mice, no obvious abnormalities of satellite cells or muscle regenerative potentials are observed. However, the generation of undifferentiated quiescent satellite cells is impaired during postnatal development in Hesr1/3 double-knockout mice. As a result, myogenic (MyoD and myogenin) and proliferative (Ki67) proteins are expressed in adult satellite cells. Consistent with the in vivo results, Hesr1/3-null myoblasts generate very few Pax7(+) MyoD(-) undifferentiated cells in vitro. Furthermore, the satellite cell number gradually decreases in Hesr1/3 double-knockout mice even after it has stabilized in control mice, and an age-dependent regeneration defect is observed. In vivo results suggest that premature differentiation, but not cell death, is the reason for the reduced number of satellite cells in Hesr1/3 double-knockout mice. These results indicate that Hesr1 and Hesr3 are essential for the generation of adult satellite cells and for the maintenance of skeletal muscle homeostasis.

Fibrosis and adipogenesis originate from a common mesenchymal progenitor in skeletal muscle

Accumulation of adipocytes and collagen type-I-producing cells (fibrosis) is observed in muscular dystrophies. The origin of these cells had been largely unknown, but recently we identified mesenchymal progenitors positive for platelet-derived growth factor receptor alpha (PDGFRα) as the origin of adipocytes in skeletal muscle. However, the origin of muscle fibrosis remains largely unknown. In this study, clonal analyses show that PDGFRα(+) cells also differentiate into collagen type-I-producing cells. In fact, PDGFRα(+) cells accumulated in fibrotic areas of the diaphragm in the mdx mouse, a model of Duchenne muscular dystrophy. Furthermore, mRNA of fibrosis markers was expressed exclusively in the PDGFRα(+) cell fraction in the mdx diaphragm. Importantly, TGF-β isoforms, known as potent profibrotic cytokines, induced expression of markers of fibrosis in PDGFRα(+) cells but not in myogenic cells. Transplantation studies revealed that fibrogenic PDGFRα(+) cells mainly derived from pre-existing PDGFRα(+) cells and that the contribution of PDGFRα(-) cells and circulating cells was limited. These results indicate that mesenchymal progenitors are the main origin of not only fat accumulation but also fibrosis in skeletal muscle.

Abstract P1-13-09: Marked Inhibition of Both Invasion and Proliferation by Zoledronic Acid and the Epidermal Growth Factor Receptor Inhibitor Gefitinib in a Bone-Seeking Clone of Breast Cancer

Background: Zoledronic acid (Zol) is the most potent inhibitor of bone resorption in bisphosphonates. In order to examine whether the inhibitory effect is involved in the mechanism of bone metastasis in breast cancer, a bone-seeking clone was examined. It was established by repeated sequential passages of metastatic cells from bone in nude mice and in vitro, and it exclusively metastasizes to bone with larger osteolytic lesions than MDA-MB-231 parental cells. Recent findings indicate that epidermal growth factor (EGF) signaling is also an important mediator of bone metastasis. We examined the synergistic effects of gefitinib on the proliferation and invasion of a bone-seeking clone compared with MDA-MB-231. Materials and Methods: The cellular proliferation was estimated using WST-1. Migration in the matrigel in a Boyden chamber was applied to the invasion assay.

Results: Treatment with 1 µM of Zol reduced 51% of cell proliferation in the bone-seeking clone; however, the inhibited rate was 37% in MDA-MB-231. The migration was also inhibited with 10 µM of Zol (bone-seeking clone: 69% reduction, MDA-MB-231: 54% reduction). The reduction rates of both assays by Zol treatment were significantly higher in the bone-seeking clone than in MDA-MB-231. Treatment with 10 µM of Zol plus 1 µM of gefitinib resulted in a proliferation reduction rate of 27% compared to that with 10 µM Zol treatment in the bone-seeking clone and no reduction in MDA-MB-231.

The migration reduction rate was 88% in the bone-seeking clone and no reduction in MDA-MB-231.

There was a significant difference between the bone-seeking clone and MDA-MB-231 in the reduction rates of both cellular proliferation and migration. Although the effect of gefitinib was synergistic with that of Zol in the bone-seeking clone, it was not clear in MDA-MB-231.

Conclusion: There appear to be at least two independent signaling pathways that occur in osteolytic bone metastasis. One is involved in the bone resorption of bisphosphonates, and the other is an EGFR signaling pathway. Clinically, the combination of Zol and gefitinib is suggested to be a strong therapy specific to bone metastasis.

Abstract P2-07-01: Simvastatin Prevents Breast Cancer Skeletal Metastasis by Increasing p53 Levels To Increase PTEN and Inhibit CD44 Expression

Bone represents one of the main sites of metastatic spread of breast cancer. The prognosis for the breast cancer patients with bone metastasis is very poor with severely compromised life style associated with extreme bone pain and fracture prevalence. We used heart injection model to test the effect of simvastatin on breast cancer bone metastasis. Simvastatin prevented osteolytic lesions in mice injected with MDA-MB-231 (MDA) human breast cancer cells, indicating that statin attenuates breast cancer metastasis to bone. To investigate the mechanism, MDA cells were used in an in vitro wound-healing assay. Simvastatin significantly inhibited the migration of MDA cells. Transwell invasion assay using collagen-coated discs confirmed the inhibitory effect of simvastatin on breast cancer cell invasion. We have recently shown that simvastatin inhibits primary tumor growth in mice by upregulating the tumor suppressor PTEN. Overexpression of PTEN in MDA cells significantly blocked their ability to migrate and invade. To determine the mechanism of PTEN upregulation, we considered the tumor suppressor protein p53, which is known to regulate PTEN expression. Simvastatin-treated mice tumors showed significantly increased levels of p53. Similarly, simvastatin enhanced the expression of p53 in MDA cells. Additionally, simvastatin increased transcription of the reporter plasmids containing the consensus p53-binding element (p53-Luc) or the PTEN promoter (PTEN-Luc). Cotransfection of p53 with these reporter constructs resulted in similar increase in transcription, indicating a role of p53 in PTEN expression by simvastatin. Recent reports indicate a direct correlation between expression of CD44 in breast cancer and their metastasis to other organs including bone. Levels of CD44 were significantly reduced in the tumors of mice treated with simvastatin. In MDA cells, simvastatin decreased the expression of CD44 protein and its transcription, as determined by CD44 promoter-driven luciferase construct (CD44-Luc). p53 acts as transcriptional activator or transcriptional repressor in a cell-type and context-dependent manner. Presence of non-canonical p53-binding elements has been reported in the CD44 promoter. Cotransfection of p53 with CD44-Luc significantly suppressed the transcription of CD44. Furthermore, expression of p53 markedly reduced the expression of CD44 protein. Finally, downregulation of endogenous CD44 by specific shRNA decreased migration of MDA cells. Together these results uncover a novel action of simvastatin, which targets p53 expression to simultaneously increase PTEN and decrease CD44 thus blocking migration and preventing bone metastasis of the human breast cancer cells.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-07-01.

Phenotypic analysis of Dlx5 overexpression in post-natal bone

Dlx5 plays an important role in the embryonic development of mineralized tissues. We hypothesized that Dlx5 also functions in regulating post-natal bone formation in mice. To prove this hypothesis, we infected 5-day-old bone sialoprotein (BSP)/avian retroviral receptor gene (TVA) transgenic mice with replication-competent retroviral vectors expressing wild-type Dlx5 (RCAS-Dlx5WT) and mutated Dlx5 at arginine (R) 31 of its homeodomain (RCAS-Dlx5RH). Immunohistochemistry indicated that RCAS-Dlx5WT increased BSP and osteopontin (OPN) expression, whereas it decreased that of osteocalcin (OC). RCAS-Dlx5RH mediated opposite effects. Semi-quantitative RT-PCR confirmed these results. Ex vivo overexpression of RCAS-Dlx5WT in BSP/TVA calvarial cells promoted, whereas that of RCAS-Dlx5RH inhibited, mineralized nodule formation as compared with that in control cells. Our results suggest that Dlx5 promotes expression of early markers of osteogenic differentiation and increases mineralization post-natally.

Pentosidine and Its Deposition in Renal Tissue in Renal Transplantation

BACKGROUND

Advanced glycation end products (AGEs) accumulate in lesions of arteriosclerosis, Alzheimer's disease, rheumatoid arthritis, diabetic retinopathy, and diabetic nephropathy. Among AGEs, chemical quantification and immunohistologic methods for pentosidine have been established. Free pentosidine-eliminated by renal excretion- is mainly affected by renal function. In this study, we measured concentrations of plasma free and total pentosidine and immunohistologically investigated kidney graft biopsy specimens in patients after renal transplantation to investigate the renal function, plasma free and total pentosidine, and its relationship with deposition in the renal tissue.

PATIENTS AND METHODS

In 28 patients who underwent renal transplantation from 1996 to 2003, we measured the time course of plasma concentrations of free pentosidine, total pentosidine, and serum creatinine starting right after renal transplantation. Thirty-four graft biopsy specimens were immunohistologically investigated using anti-pentosidine antibody. Plasma free and total pentosidine, and serum creatinine were measured at the same time.

RESULTS

Plasma free and total pentosidine were positively correlated with serum creatinine. Plasma free pentosidine and serum creatinine reached nadir values on day 34.2 +/- 14.2, when the blood concentrations were 5.1 +/- 1.6 pmol/mL and 1.7 +/- 0.7 mg/dL, respectively. Plasma total pentosidine reached a nadir on day 116.5 +/- 39.7 when the plasma concentration was 4.0 +/- 1.5 pmol/mg. We correlated the time required to reach the nadir of plasma free and total pentosidine concentrations. However, neither the concentration of plasma free nor plasma total pentosidine at nadir correlated with serum creatinine. The intensity of immunostaining with anti-pentosidine antibody in proximal tubular cells was graded as weakly positive, positive, or strongly positive. Significant differences were obtained among plasma free pentosidine values between the weakly positive and strongly positive groups.

CONCLUSIONS

Renal transplantation improves renal function and decreases renal excretion of free pentosidine. Accordingly, total pentosidine also decreases. However, the concentrations of plasma free and total pentosidine at nadir varied among individuals; the blood concentrations were not determined by renal function alone. It was suggested that deposition of pentosidine in proximal tubular cells was more severe among patients with higher plasma free pentosidine and serum creatinine values.

PRKAR1A gene mutation in patients with cardiac myxoma

BACKGROUND

PRKAR1A gene encodes the type 1A regulatory subunit of protein kinase A. The mutation of this gene causes Carney complex which is an autosomal dominant multiple neoplasia syndrome characterized by spotty pigmentations, endocrine overactivity and cardiac myxoma. We hypothesized that cardiac myxoma may be associated with PRKAR1A gene mutation and determined whether mutation in the PRKAR1A gene is the cause of familial and sporadic cardiac myxoma.

METHODS

We studied seven patients (three males and four females) with cardiac myxoma. Two of them had familial cardiac myxoma complicated with Carney complex. The other five patients were characterized as sporadic cardiac myxomas. We analyzed the PRKAR1A gene of all patients by the polymerase chain reaction (PCR)-single-strand conformation method, followed with direct sequence analysis.

RESULTS

We identified a novel mutation (494delTG) in exon 4A of the PRKAR1A gene in the patients with Carney complex. A 16-year-old proband had a left atrial myxoma, pituitary adenoma and skin pigmentation. His father also had left atrial myxoma and skin pigmentation. In contrast, no mutations in the PRKAR1A gene were identified in the other five patients with sporadic cardiac myxomas.

CONCLUSIONS

These results suggest that mutation of the PRKAR1A gene may be associated with familial cardiac myxoma in Carney complex but may not be associated with sporadic cardiac myxoma.

Bone sialoprotein promotes bone metastasis of a non-bone-seeking clone of human breast cancer cells

Bone sialoprotein (BSP) is a major non-collagenous protein in mineralized tissues. BSP is also implied to be involved in tumor metastasis through its unique structure. Using the human breast cancer cell line MDA-231, we established both brain-seeking and bone-seeking cell clones. The brain-seeking cells (MDA4-231BR) showed no bone metastasis in an animal model. In this experiment, MDA-231BR cells were transfected with BSP cDNA and inoculated into the hearts of nude mice. All five nude mice which received BSP-transfected MDA-231BR cells developed bone metastases, while no bone lesions were observed in the control group. Histological examination revealed invasion of tumor cells into the endosteal space and erosion of the bone margin. Some animals were crippled due to large lesions. These results suggest that BSP may impart to breast cancer cells the capacity to metastasize and thus play an important role in bone metastasis of malignant tumors.

Bone sialoprotein promotes tumor cell migration in both in vitro and in vivo models

The present study was conducted to determine the effects of bone sialoprotein (BSP) in promoting vascular invasion of tumor cells in metastasis. We used a Matrigel system and the MDA-231 human breast cancer cells transfected with human BSP cDNA (MDA-231/BSP). Quantative analysis indicated an average of 1.7-fold increase in cell numbers that migrated through the endothelial cells in MDA-231/BSP cells compared with empty vector-transfected MDA-231 cells (MDA-231/EV). In an in vivo assay, the MDA-231 cells were incubated with or without BSP antibodies and were then inoculated onto the upper chorioallantoic membrane (CAM) of chicken embryos, in which the only route for the tumor cells to reach the lower CAM was to migrate through the embryonic vasculature. PCR amplification using human Alu primers and genomic DNA from harvested lower CAM showed an average reduction of 67% in the samples treated with BSP antibodies. These preliminary data suggest that, in metastasis, BSP may enhance the penetrating ability of tumor cells through endothelial cells and basement membrane into blood vessels. BSP antibodies can specifically hinder this effect in an in vivo system.

Bisphosphonate actions on cancer

Bisphosphonates (BPs) suppress cancer cell colonization in bone associated with cancers such as breast cancer and multiple myeloma. The mechanism of the suppressive action of BPs is thought to be due to an inhibition of osteoclastic bone resorption which releases bone-stored growth factors that feed cancer cells colonizing bone. Recently, data are accumulating that BP suppresses growth and induces apoptosis in cancer cells in culture, suggesting that BP directly influences survival of cancer cells in an osteoclast-independent manner. These results raise the possibility that BP inhibits cancer growth in organs other than bone. However, evidence is limited that BP reduces tumor growth in non-bone sites in cancer patients. In this review, we discuss the effectiveness of BP on breast cancer colonization in non-bone sites and our results in animal models with metastases. With currently available clinical and in vivo experimental data, BPs are definitely beneficial for the treatment of cancer patients who manifest clinically detectable bone metastases. However, it is not recommended that BP be given as a preventative to patients with visceral metastases and of no evidence of bone metastases. Whether individual BP with different chemical structure has unique biological or biochemical action is an intriguing question but open at the moment.

Core-binding factor alpha 1 (Cbfa1) induces osteoblastic differentiation of C2C12 cells without interactions with Smad1 and Smad5

Core-binding factor alpha(1) (Cbfa1) is an essential transcription factor for osteoblastic differentiation and osteogenesis. Bone morphogenetic protein (BMP) is also a powerful inducer of differentiation of pluripotent mesenchymal cells to osteoblast lineage and bone formation. Recent studies suggest that Cbfa1 plays a critical role during BMP-induced osteoblastic differentiation through association with cytoplasmic BMP signaling molecules, Smads. However, other studies have suggested that Cbfa1 may exhibit its osteogenic function without interaction with Smads. Therefore, it remains unclear whether association with Smad is essential for Cbfa1 function. In this study we examine the effects of Cbfa1 on osteoblastic differentiation in the presence or absence of interactions with Smad1 or Smad5 using C2C12 undifferentiated mesenchymal cells. Cbfa1 expression was induced upon stimulation with BMP-2 in C2C12 cells. Introduction of Cbfa1 into C2C12 cells induced osteoblastic differentiation and promoted transactivation of osteocalcin gene promoter without forming the complex with Smad1 or Smad5. Furthermore, in C2C12 cells in which the association of Cbfa1 with Smad1/Smad5 was prevented by the overexpression of the natural antagonist, Smad6, Cbfa1 still induced osteoblastic differentiation and transactivated osteocalcin gene promoter, regardless of BMP-2 stimulation. These results suggest that the interactions with Smad1 or Smad5 are not essential for Cbfa1 to demonstrate its osteogenic actions. However, interactions with Smad1/Smad5 enhance these osteogenic actions of Cbfa1. Of note, BMP-2-induced or Smad-induced osteoblastic differentiation was inhibited by dominant-negative Cbfa1, suggesting that the function of Cbfa1 is critical for BMP-2-induced osteoblastic differentiation. Our results suggest that Cbfa1 is essential and also sufficient to induce osteoblastic differentiation in undifferentiated mesenchymal cells, and establishment of an association with Smad1/Smad5 enhances the osteogenic actions of Cbfa1. On the other hand, Cbfa1 expression requires the activation of Smad1/Smad5 by BMP-2.

Mechanisms of action of the novel sulfonamide anticancer agent E7070 on cell cycle progression in human non-small cell lung cancer cells

E7070 is a novel sulfonamide antitumor agent that exhibits potent antitumor activity in vitro and in vivo. This compound affects cell cycle progression in human tumor cells. To elucidate the mechanisms by which E7070 inhibits tumor cell growth, we established and characterized an E7070-resistant subline, A549/ER, from a human non-small cell lung cancer cell line A549. Flow cytometric analyses demonstrated an increase in G0/G1 and a decrease in S phase populations in cells treated with E7070 at 20 or 100 microg/ml for 24 h. Longer exposure to E7070, i.e. 48 and 72 h, increased the G2/M phase fraction in A549 cells. These inhibitory actions of E7070 on cell cycle progression were not observed in A549/ER cells. E7070 inhibited the phosphorylation of pRb, decreased expressions of cyclin A, B1, CDK2, and CDC2 proteins, and suppressed CDK2 catalytic activity with the induction of p53 and p21 proteins in A549 cells but not in A549/ER cells. Taken together, these results suggest that E7070 exerts its antitumor effects by disturbing the cell cycle at multiple points, including both the G1/S and the G2/M transition, in human lung cancer cells.

Multilocular spermatocele: a case report

We describe a case of a multilocular spermatocele. Ultrasound examination revealed several cystic spaces at the head of the left epididymis. Epididymal tumor could not be excluded, and therefore surgical exploration was performed. Histopathological examination of the specimen revealed a multilocular spermatocele arising from the rete testis. Most spermatoceles remain small and rarely present marked clinical problems. but they are occasionally large, and may simulate a solid tumor.