Assessing physical properties of amphoteric fluoroquinolones using phosphorescence spectroscopy

[EN] The self-association of fluoroquinolones (FQ) in water would play a relevant role in their translocations across lipid membranes. Triplet excited states of these drugs have been shown as reporters of FQ self-association using laser flash photolysis technique. A study using low-temperature phosphorescence technique was performed with quinolone derivatives such as enoxacin (ENX), norfloxacin (NFX), pefloxacin (PFX), ciprofloxacin (CPX, ofloxacin (OFX), nalidixic acid (NLA), pipemidic acid (PPA) and piromidic acid (PRA) to explore emission changes associated with self-associations and to shed some light on the triplet excited state energy (E-T) discrepancies described in the literature for most of these drugs. The emissions obtained at 77 K in buffered aqueous medium revealed that the amphoteric nature of the quinolones CPX, NFX, PFX, ENX, OFX and PPA must generate their self-associations because a redshift of their phosphorescence maxima is produced by FQ concentrations increases. Hence, this effect was not observed for NLA and PRA or when all quinolones were analysed using ethanol or ethylene glycol aqueous mixtures as glassed solvents. Interestingly, the presence of these organic mixtures produced a blue-shift in the phosphorescence emission maximum of each FQ. Additionally, laser flash photolysis experiments with PRA and the amphoteric quinolone PPA, compounds with the same skeleton but different peripheral substituent, confirm the expected correlations between the amphoteric nature of compounds and their self-associations in aqueous media because the excimer generation was only detected for PPA. Now, the discrepancies described in the literature for the ET of FQs can be understood considering that changes of medium polarity or proticity as well as the temperature can considerably modify their ET values. Thereby, low-temperature phosphorescence technique, is an effective way to detect molecular self-associations and surrounding changes in quinolones that opens the possibility to evaluate these effects in other drug families. (C) 2019 Elsevier B.V. All rights reserved.Financial support from Spanish government (grant CTQ2014-54729-C2-2-P) and the Generalitat Valenciana (PROMETEO program, 2017-075).Soldevila Serrano, S.; Bosca Mayans, F. (2020). Assessing physical properties of amphoteric fluoroquinolones using phosphorescence spectroscopy. Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy. 227:1-7. https://doi.org/10.1016/j.saa.2019.117569S17227Domagala, J. M., Hanna, L. D., Heifetz, C. L., Hutt, M. P., Mich, T. F., Sanchez, J. P., & Solomon, M. (1986). New structure-activity relationships of the quinolone antibacterials using the target enzyme. The development and application of a DNA gyrase assay. Journal of Medicinal Chemistry, 29(3), 394-404. doi:10.1021/jm00153a015Cramariuc, O., Rog, T., Javanainen, M., Monticelli, L., Polishchuk, A. V., & Vattulainen, I. (2012). Mechanism for translocation of fluoroquinolones across lipid membranes. Biochimica et Biophysica Acta (BBA) - Biomembranes, 1818(11), 2563-2571. doi:10.1016/j.bbamem.2012.05.027Sun, J., Sakai, S., Tauchi, Y., Deguchi, Y., Chen, J., Zhang, R., & Morimoto, K. (2002). Determination of lipophilicity of two quinolone antibacterials, ciprofloxacin and grepafloxacin, in the protonation equilibrium. European Journal of Pharmaceutics and Biopharmaceutics, 54(1), 51-58. doi:10.1016/s0939-6411(02)00018-8Sun, J., Sakai, S., Tauchi, Y., Deguchi, Y., Cheng, G., Chen, J., & Morimoto, K. (2003). Protonation equilibrium and lipophilicity of olamufloxacin (HSR-903), a newly synthesized fluoroquinolone antibacterial. European Journal of Pharmaceutics and Biopharmaceutics, 56(2), 223-229. doi:10.1016/s0939-6411(03)00099-7Furet, Y. X., Deshusses, J., & Pechère, J. C. (1992). Transport of pefloxacin across the bacterial cytoplasmic membrane in quinolone-susceptible Staphylococcus aureus. Antimicrobial Agents and Chemotherapy, 36(11), 2506-2511. doi:10.1128/aac.36.11.2506Maurer, N., Wong, K. F., Hope, M. J., & Cullis, P. R. (1998). Anomalous solubility behavior of the antibiotic ciprofloxacin encapsulated in liposomes: a 1H-NMR study. Biochimica et Biophysica Acta (BBA) - Biomembranes, 1374(1-2), 9-20. doi:10.1016/s0005-2736(98)00125-4Cuquerella, M. C., Andreu, I., Soldevila, S., & Bosca, F. (2012). Triplet Excimers of Fluoroquinolones in Aqueous Media. The Journal of Physical Chemistry A, 116(21), 5030-5038. doi:10.1021/jp301800qLhiaubet-Vallet, V., Sarabia, Z., Boscá, F., & Miranda, M. A. (2004). Human Serum Albumin-Mediated Stereodifferentiation in the Triplet State Behavior of (S)- and (R)-Carprofen. Journal of the American Chemical Society, 126(31), 9538-9539. doi:10.1021/ja048518gBosca, F. (2012). Seeking to Shed Some Light on the Binding of Fluoroquinolones to Albumins. The Journal of Physical Chemistry B, 116(11), 3504-3511. doi:10.1021/jp208930qCuquerella, M. C., Lhiaubet-Vallet, V., Miranda, M. A., & Bosca, F. (2017). Drug–DNA complexation as the key factor in photosensitized thymine dimerization. Physical Chemistry Chemical Physics, 19(7), 4951-4955. doi:10.1039/c6cp08485kAlfredson, T. V., Maki, A. H., & Waring, M. J. (1991). Optically detected triplet-state magnetic resonance studies of the DNA complexes of the bisquinoline analog of echinomycin. Biochemistry, 30(40), 9665-9675. doi:10.1021/bi00104a014Alfredson, T. V., & Maki, A. H. (1990). Phosphorescence and optically detected magnetic resonance studies of echinomycin-DNA complexes. Biochemistry, 29(38), 9052-9064. doi:10.1021/bi00490a024Li, J., Li, J., Shuang, S., & Dong, C. (2005). Study of the luminescence behavior of seven quinolones on a paper substrate. Analytica Chimica Acta, 548(1-2), 134-142. doi:10.1016/j.aca.2005.04.053Sun, C., Ping, H., Zhang, M., Li, H., & Guan, F. (2011). Spectroscopic studies on the lanthanide sensitized luminescence and chemiluminescence properties of fluoroquinolone with different structure. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 82(1), 375-382. doi:10.1016/j.saa.2011.07.065Rieutord, A., Vazquez, L., Soursac, M., Prognon, P., Blais, J., Bourget, P., & Mahuzier, G. (1994). Fluoroquinolones as sensitizers of lanthanide fluorescence: application to the liquid chromatographic determination of ciprofloxacin using terbium. Analytica Chimica Acta, 290(1-2), 215-225. doi:10.1016/0003-2670(94)80058-8Sortino, S., De Guidi, G., Giuffrida, S., Monti, S., & Velardita, A. (1998). pH Effects on the Spectroscopic and Photochemical Behavior of Enoxacin: A Steady-State and Time-Resolved Study. Photochemistry and Photobiology, 67(2), 167. doi:10.1562/0031-8655(1998)0672.3.co;2Martínez, L., Bilski, P., & Chignell, C. F. (1996). Effect of Magnesium and Calcium Complexation on the Photochemical Properties of Norfloxacin. Photochemistry and Photobiology, 64(6), 911-917. doi:10.1111/j.1751-1097.1996.tb01855.xBilski, P., Martinez, L. J., Koker, E. B., & Chignell, C. F. (1996). Photosensitization by Norfloxacin is a Function of pH. Photochemistry and Photobiology, 64(3), 496-500. doi:10.1111/j.1751-1097.1996.tb03096.xBosca, F., Lhiaubet-Vallet, V., Cuquerella, M. C., Castell, J. V., & Miranda, M. A. (2006). The Triplet Energy of Thymine in DNA. Journal of the American Chemical Society, 128(19), 6318-6319. doi:10.1021/ja060651gLhiaubet-Vallet, V., Cuquerella, M. C., Castell, J. V., Bosca, F., & Miranda, M. A. (2007). Triplet Excited Fluoroquinolones as Mediators for Thymine Cyclobutane Dimer Formation in DNA. The Journal of Physical Chemistry B, 111(25), 7409-7414. doi:10.1021/jp070167fCuquerella, M. C., Lhiaubet-Vallet, V., Bosca, F., & Miranda, M. A. (2011). Photosensitised pyrimidine dimerisation in DNA. Chemical Science, 2(7), 1219. doi:10.1039/c1sc00088hLhiaubet-Vallet, V., Bosca, F., & Miranda, M. A. (2009). Photosensitized DNA Damage: The Case of Fluoroquinolones. Photochemistry and Photobiology, 85(4), 861-868. doi:10.1111/j.1751-1097.2009.00548.xAlbini, A., & Monti, S. (2003). Photophysics and photochemistry of fluoroquinolones. Chemical Society Reviews, 32(4), 238. doi:10.1039/b209220bCuquerella, M. C., Miranda, M. A., & Bosca, F. (2006). Role of Excited State Intramolecular Charge Transfer in the Photophysical Properties of Norfloxacin and Its Derivatives. The Journal of Physical Chemistry A, 110(8), 2607-2612. doi:10.1021/jp0559837Lorenzo, F., Navaratnam, S., & Allen, N. S. (2008). Formation of Secondary Triplet Species after Excitation of Fluoroquinolones in the Presence of Relatively Strong Bases. Journal of the American Chemical Society, 130(37), 12238-12239. doi:10.1021/ja804471

The monoclonal antibody nBT062 conjugated to maytansinoids has potent and selective cytotoxicity against CD138 positive multiple myeloma cells _in vitro_ and _in vivo_

CD138 (Syndecan1) is highly expressed on multiple myeloma (MM) cells. In this study, we examined the anti-MM effect of murine/human chimeric CD138-specific monoclonal antibody (mAb) nBT062 conjugated with highly cytotoxic maytansinoid derivatives _in vitro_ and _in vivo_. These agents significantly inhibited growth of CD138-positive MM cell lines and primary tumor cells from MM patients, without cytotoxicity against peripheral blood mononuclear cells from healthy volunteers. In MM cells, they induced G2/M cell cycle arrest followed by apoptosis associated with cleavage of PARP and caspase-3, -8 and -9. Non-conjugated nBT062 completely blocked cytotoxicity induced by nBT062-maytansinoid conjugate, confirming that binding is required for inducing cytotoxicity. Moreover, nBT062-maytansinoid conjugates blocked adhesion of MM cells to bone marrow stromal cells (BMSCs). Co-culture of MM cells with BMSCs, which protects against dexamethasone-induced death, had no impact on the cytotoxicity of the immunoconjugates. Importantly, nBT062-SPDB-DM4 and nBT062-SPP-DM1 significantly inhibited MM tumor growth _in vivo_ in both human multiple myeloma xenograft mouse models and in SCID-human bone grafts (SCID-hu mouse model). These studies provide the preclinical framework supporting evaluation of nBT062-maytansinoid derivatives in clinical trials to improve patient outcome in MM

A Novel Role for CCL3 (MIP-1α) in Myeloma-induced Bone Disease via Osteocalcin Downregulation and Inhibition of Osteoblast Function

Upregulation of cytokines and chemokines is a frequent finding in multiple myeloma (MM). CCL3 (also known as MIP-1α) is a pro-inflammatory chemokine whose levels in the MM microenvironment correlate with osteolytic lesions and tumor burden. CCL3 and its receptors, CCR1 and CCR5, contribute to the development of bone disease in MM by supporting tumor growth and regulating osteoclast (OC) differentiation. Here, we identify inhibition of osteoblast (OB) function as an additional pathogenic mechanism in CCL3-induced bone disease. MM-derived and exogenous CCL3 represses mineralization and osteocalcin production by primary human bone marrow stromal cells and HS27A cells. Our results suggest that CCL3 effects on OBs are mediated by ERK activation and subsequent downregulation of the osteogenic transcription factor osterix. CCR1 inhibition reduced ERK phosphorylation and restored both osterix and osteocalcin expression in the presence of CCL3. Finally, treating SCID-hu mice with a small molecule CCR1 inhibitor suggests an upregulation of osteocalcin expression along with OC downregulation. Our results show that CCL3, in addition to its known catabolic activity, reduces bone formation by inhibiting OB function and therefore contributes to OB/OC uncoupling in MM

Achievements in Mesoporous Bioactive Glasses for Biomedical Applications

Nowadays, mesoporous bioactive glasses (MBGs) are envisaged as promising candidates in the field of bioceramics for bone tissue regeneration. This is ascribed to their singular chemical composition, structural and textural properties and easy-to-functionalize surface, giving rise to accelerated bioactive responses and capacity for local drug delivery. Since their discovery at the beginning of the 21st century, pioneering research efforts focused on the design and fabrication of MBGs with optimal compositional, textural and structural properties to elicit superior bioactive behavior. The current trends conceive MBGs as multitherapy systems for the treatment of bonerelated pathologies, emphasizing the need of fine-tuning surface functionalization. Herein, we focus on the recent developments in MBGs for biomedical applications. First, the role of MBGs in the design and fabrication of three-dimensional scaffolds that fulfil the highly demanding requirements for bone tissue engineering is outlined. The different approaches for developing multifunctional MBGs are overviewed, including the incorporation of therapeutic ions in the glass composition and the surface functionalization with zwitterionic moieties to prevent bacterial adhesion. The bourgeoning scientific literature on MBGs as local delivery systems of diverse therapeutic cargoes (osteogenic/antiosteoporotic, angiogenic, antibacterial, anti-inflammatory and antitumor agents) is addressed. Finally, the current challenges and future directions for the clinical translation of MBGs are discussed

Strontium-releasing mesoporous bioactive glasses with anti-adhesive zwitterionic surface as advanced biomaterials for bone tissue regeneration

Hypothesis The treatment of bone fractures still represents a challenging clinical issue when complications due to impaired bone remodelling (i.e. osteoporosis) or infections occur. These clinical needs still require a radical improvement of the existing therapeutic approach through the design of advanced biomaterials combining the ability to promote bone regeneration with anti-adhesive properties able to minimise unspecific biomolecules adsorption and bacterial adhesion. Strontium-containing mesoporous bioactive glasses (Sr-MBG), which are able to exert a pro-osteogenic effect by releasing Sr2+ ions, have been successfully functionalised to provide mixed-charge (-NH3 /-COO⊝) surface groups with anti-adhesive abilities. Experiments Sr-MBG have been post-synthesis modified by co-grafting hydrolysable short chain silanes containing amino (aminopropylsilanetriol) and carboxylate (carboxyethylsilanetriol) moieties to achieve a zwitterionic zero-charge surface. The final system was then characterised in terms of textural-structural properties, bioactivity, cytotoxicity, pro-osteogenic and anti-adhesive capabilities. Findings After zwitterionization the in vitro bioactivity was maintained, as well as the ability to release Sr2+ ions which are capable of inducing a mineralization process. Irrespective of their size, Sr-MBG particles did not exhibit any cytotoxicity in pre-osteoblastic MC3T3-E1 up to the concentration of 75 µg/mL. Finally, the zwitterionic Sr-MBGs showed a significant reduction of serum protein adhesion with respect to the pristine ones. These results open promising future expectations in the design of nanosystems which combine pro-osteogenic and anti-adhesive properties

Retraction: Fatty acid synthase is a novel therapeutic target in multiple myeloma

This study investigated the biological significance of the inhibition of fatty acid synthase (FAS) in multiple myeloma (MM) using the small molecule inhibitor Cerulenin. Cerulenin triggered growth inhibition in both MM cell lines and MM patient cells, and overcame the survival and growth advantages conferred by interleukin-6, insulin-like growth factor-1, and bone marrow stromal cells. It induced apoptosis in MM cell lines with only modest activation of caspase -8, -9, -3 and PARP; moreover, the pan-caspase inhibitor Z-VAD-FMK did not inhibit Cerulenin-induced apoptosis and cell death. In addition, treatment of MM cells with Cerulenin primarily up-regulated apoptosis-inducing factor/endonuclease G, mediators of caspase-independent apoptosis. Importantly, Cerulenin induced endoplasmic reticulum stress response via up-regulation of the Grp78/IRE1α/JNK pathway. Although the C-Jun-NH2-terminal kinase (JNK) inhibitor SP600215 blocked Cerulenin-induced cytotoxicity, it did not inhibit apoptosis and caspase cleavage. Furthermore, Cerulenin showed synergistic cytotoxic effects with various agents including Bortezomib, Melphalan and Doxorubicin. Our results therefore indicate that inhibition of FAS by Cerulenin primarily triggered caspase-independent apoptosis and JNK-dependent cytotoxicity in MM cells. This report demonstrated that inhibition of FAS has anti-tumour activity against MM cells, suggesting that it represents a novel therapeutic target in MM

Chemical tuning for potential antitumor fluoroquinolones

[EN] Phototoxic effects of 6,8 dihalogenated quinolones confers to this type of molecules a potential property as photochemotherapeutic agents. Two photodehalogenation processes seem to be involved in the remarkable photoinduced cellular damage. In this context, a new 6,8 dihalogenated quinolone 1 (1-methyl-6,8-difluoro-4-oxo-7-aminodimethy1-1,4-dihydroquinoline-3-carboxylic acid) was synthesized looking for improving the phototoxic properties of fluoroquinolones (FQ) and to determine the role of the photodegradation pathways in the FQ phototoxicity. With this purpose, fluorescence emissions, laser flash photolysis experiments and photodegradation studies were performed with compound 1 using 1-ethyl-6,8-difluoro-4-oxo-7-aminodimethy1-1,4-dihidroquinoline-3-carboxylic acid (2) and lomefloxacin (LFX) as reference compounds. The shortening of alkyl chain of the N(1) of the quinolone ring revealed a lifetime increase of the reactive aryl cation generated from photolysis of the three FQ and a significant reduction of the FQ photodegradation quantum yield. The fact that these differences were smaller when the same study was done using a hydrogen donor solvent (ethanol-aqueous buffer, 50/50 v/v) evidenced the highest ability of the reactive intermediate arising from 1 to produce intermolecular alkylations. These results were correlated with in vitro 3T3 NRU phototoxicity test. Thus, when PhotoIrritation-Factor (PIF) was determined for 1, 2 and LFX using cytotoxicity profiles of BALB/c 3T3 fibroblasts treated with each compound in the presence and absence of UVA light, a PIF more higher than 30 was obtained for 1 while the values for 2 and LFX were only higher than 8 and 10, respectively. Thereby, the present study illustrates an approach to modulate the photosensitizing properties of FQ with the purpose to improve the chemotherapeutic properties of antitumor quinolones. Moreover, the results obtained in this study also evidence that the key pathway responsible for the phototoxic properties associated with dihalogenated quinolones is the aryl cation generation.Financial support from Spanish government (MINECO grant CTQ2014-54729-C2-2-P and Severo Ochoa fellowship for C. A., Carlos III Institute of Health grant PI16/01877), and the Generalitat Valenciana (PROMETEO program, 2017-075). We thank M.P. Marin of IIS La Fe Microscopy Unit for confocal microscopy.Anaya-González, C.; Soldevila Serrano, S.; García-Laínez, G.; Bosca Mayans, F.; Andreu Ros, MI. (2019). Chemical tuning for potential antitumor fluoroquinolones. Free Radical Biology and Medicine. 141:150-158. https://doi.org/10.1016/j.freeradbiomed.2019.06.010S150158141Domagala, J. M., Hanna, L. D., Heifetz, C. L., Hutt, M. P., Mich, T. F., Sanchez, J. P., & Solomon, M. (1986). New structure-activity relationships of the quinolone antibacterials using the target enzyme. The development and application of a DNA gyrase assay. Journal of Medicinal Chemistry, 29(3), 394-404. doi:10.1021/jm00153a015Kang, D.-H., Kim, J.-S., Jung, M.-J., Lee, E.-S., Jahng, Y., Kwon, Y., & Na, Y. (2008). New insight for fluoroquinophenoxazine derivatives as possibly new potent topoisomerase I inhibitor. Bioorganic & Medicinal Chemistry Letters, 18(4), 1520-1524. doi:10.1016/j.bmcl.2007.12.053Azéma, J., Guidetti, B., Dewelle, J., Le Calve, B., Mijatovic, T., Korolyov, A., … Kiss, R. (2009). 7-((4-Substituted)piperazin-1-yl) derivatives of ciprofloxacin: Synthesis and in vitro biological evaluation as potential antitumor agents. Bioorganic & Medicinal Chemistry, 17(15), 5396-5407. doi:10.1016/j.bmc.2009.06.053Cullen, M., & Baijal, S. (2009). Prevention of febrile neutropenia: use of prophylactic antibiotics. British Journal of Cancer, 101(S1), S11-S14. doi:10.1038/sj.bjc.6605270Kim, K., Pollard, J. M., Norris, A. J., McDonald, J. T., Sun, Y., Micewicz, E., … McBride, W. H. (2009). High-Throughput Screening Identifies Two Classes of Antibiotics as Radioprotectors: Tetracyclines and Fluoroquinolones. Clinical Cancer Research, 15(23), 7238-7245. doi:10.1158/1078-0432.ccr-09-1964Al-Trawneh, S. A., Zahra, J. A., Kamal, M. R., El-Abadelah, M. M., Zani, F., Incerti, M., … Vicini, P. (2010). Synthesis and biological evaluation of tetracyclic fluoroquinolones as antibacterial and anticancer agents. Bioorganic & Medicinal Chemistry, 18(16), 5873-5884. doi:10.1016/j.bmc.2010.06.098Aldred, K. J., Schwanz, H. A., Li, G., Williamson, B. H., McPherson, S. A., Turnbough, C. L., … Osheroff, N. (2015). Activity of Quinolone CP-115,955 Against Bacterial and Human Type II Topoisomerases Is Mediated by Different Interactions. Biochemistry, 54(5), 1278-1286. doi:10.1021/bi501073vPommier, Y., Leo, E., Zhang, H., & Marchand, C. (2010). DNA Topoisomerases and Their Poisoning by Anticancer and Antibacterial Drugs. Chemistry & Biology, 17(5), 421-433. doi:10.1016/j.chembiol.2010.04.012Palumbo, M., Gatto, B., Zagotto, G., & Palù, G. (1993). On the mechanism of action of quinolone drugs. Trends in Microbiology, 1(6), 232-235. doi:10.1016/0966-842x(93)90138-hPaul, M., Gafter-Gvili, A., Fraser, A., & Leibovici, L. (2007). The anti-cancer effects of quinolone antibiotics? European Journal of Clinical Microbiology & Infectious Diseases, 26(11), 825-831. doi:10.1007/s10096-007-0375-4Perrone, C. E. (2002). Inhibition of Human Topoisomerase IIalpha by Fluoroquinolones and Ultraviolet A Irradiation. Toxicological Sciences, 69(1), 16-22. doi:10.1093/toxsci/69.1.16Lhiaubet-Vallet, V., Bosca, F., & Miranda, M. A. (2009). Photosensitized DNA Damage: The Case of Fluoroquinolones. Photochemistry and Photobiology, 85(4), 861-868. doi:10.1111/j.1751-1097.2009.00548.xMarrot, L., Belaïdi, J. P., Jones, C., Perez, P., Meunier, J. R., Riou, L., & Sarasin, A. (2003). Molecular Responses to Photogenotoxic Stress Induced by the Antibiotic Lomefloxacin in Human Skin Cells: From DNA Damage to Apoptosis. Journal of Investigative Dermatology, 121(3), 596-606. doi:10.1046/j.1523-1747.2003.12422.xMeunier, J.-R., Sarasin, A., & Marrot, L. (2002). Photogenotoxicity of Mammalian Cells: A Review of the Different Assays for In Vitro Testing¶. Photochemistry and Photobiology, 75(5), 437. doi:10.1562/0031-8655(2002)0752.0.co;2Martinez, L. J., Li, G., & Chignell, C. F. (1997). Photogeneration of Fluoride by the Fluoroquinolone Antimicrobial Agents Lomefloxacin and Fleroxacin. Photochemistry and Photobiology, 65(3), 599-602. doi:10.1111/j.1751-1097.1997.tb08612.xChignell, C. F., Haseman, J. K., Sik, R. H., Tennant, R. W., & Trempus, C. S. (2003). Photocarcinogenesis in the Tg.AC Mouse: Lomefloxacin and 8-Methoxypsoralen¶†. Photochemistry and Photobiology, 77(1), 77. doi:10.1562/0031-8655(2003)0772.0.co;2Fasani, E., Profumo, A., & Albini, A. (1998). Structure and Medium-Dependent Photodecomposition of Fluoroquinolone Antibiotics. Photochemistry and Photobiology, 68(5), 666-674. doi:10.1111/j.1751-1097.1998.tb02527.xJeffrey, A. M., Shao, L., Brendler-Schwaab, S. Y., Schlüter, G., & Williams, G. M. (2000). Photochemical mutagenicity of phototoxic and photochemically carcinogenic fluoroquinolones in comparison with the photostable moxifloxacin. Archives of Toxicology, 74(9), 555-559. doi:10.1007/s002040000162Spratt, T. E., Schultz, S. S., Levy, D. E., Chen, D., Schlüter, G., & Williams, G. M. (1999). Different Mechanisms for the Photoinduced Production of Oxidative DNA Damage by Fluoroquinolones Differing in Photostability. Chemical Research in Toxicology, 12(9), 809-815. doi:10.1021/tx980224jReus, A. A., Usta, M., Kenny, J. D., Clements, P. J., Pruimboom-Brees, I., Aylott, M., … Krul, C. A. . (2012). The in vivo rat skin photomicronucleus assay: phototoxicity and photogenotoxicity evaluation of six fluoroquinolones. Mutagenesis, 27(6), 721-729. doi:10.1093/mutage/ges038Soldevila, S., & Bosca, F. (2012). Photoreactivity of Fluoroquinolones: Nature of Aryl Cations Generated in Water. Organic Letters, 14(15), 3940-3943. doi:10.1021/ol301694pCuquerella, M. C., Miranda, M. A., & Boscá, F. (2006). Generation of Detectable Singlet Aryl Cations by Photodehalogenation of Fluoroquinolones. The Journal of Physical Chemistry B, 110(13), 6441-6443. doi:10.1021/jp060634dFreccero, M., Fasani, E., Mella, M., Manet, I., Monti, S., & Albini, A. (2008). Modeling the Photochemistry of the Reference Phototoxic Drug Lomefloxacin by Steady-State and Time-Resolved Experiments, and DFT and Post-HF Calculations. Chemistry - A European Journal, 14(2), 653-663. doi:10.1002/chem.200701099Albini, A., & Monti, S. (2003). Photophysics and photochemistry of fluoroquinolones. Chemical Society Reviews, 32(4), 238. doi:10.1039/b209220bFasani, E., Manet, I., Capobianco, M. L., Monti, S., Pretali, L., & Albini, A. (2010). Fluoroquinolones as potential photochemotherapeutic agents: covalent addition to guanosine monophosphate. Organic & Biomolecular Chemistry, 8(16), 3621. doi:10.1039/c0ob00056fSoldevila, S., Cuquerella, M. C., & Bosca, F. (2014). Understanding of the Photoallergic Properties of Fluoroquinolones: Photoreactivity of Lomefloxacin with Amino Acids and Albumin. Chemical Research in Toxicology, 27(4), 514-523. doi:10.1021/tx400377sSoldevila, S., Consuelo Cuquerella, M., Lhiaubet-Vallet, V., Edge, R., & Bosca, F. (2014). Seeking the mechanism responsible for fluoroquinolone photomutagenicity: a pulse radiolysis, steady-state, and laser flash photolysis study. Free Radical Biology and Medicine, 67, 417-425. doi:10.1016/j.freeradbiomed.2013.11.027Domagala, J. M., Heifetz, C. L., Hutt, M. P., Mich, T. F., Nichols, J. B., Solomon, M., & Worth, D. F. (1988). 1-Substituted 7-[3-[(ethylamino)methyl]-1-pyrrolidinyl]-6,8-difluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids. New quantitative structure activity relationships at N1 for the quinolone antibacterials. Journal of Medicinal Chemistry, 31(5), 991-1001. doi:10.1021/jm00400a017Schmidt, R., Tanielian, C., Dunsbach, R., & Wolff, C. (1994). Phenalenone, a universal reference compound for the determination of quantum yields of singlet oxygen O2(1Δg) sensitization. Journal of Photochemistry and Photobiology A: Chemistry, 79(1-2), 11-17. doi:10.1016/1010-6030(93)03746-4Garcia-Lainez, G., Martínez-Reig, A. M., Limones-Herrero, D., Consuelo Jiménez, M., Miranda, M. A., & Andreu, I. (2018). Photo(geno)toxicity changes associated with hydroxylation of the aromatic chromophores during diclofenac metabolism. Toxicology and Applied Pharmacology, 341, 51-55. doi:10.1016/j.taap.2018.01.005Palumbo, F., Garcia-Lainez, G., Limones-Herrero, D., Coloma, M. D., Escobar, J., Jiménez, M. C., … Andreu, I. (2016). Enhanced photo(geno)toxicity of demethylated chlorpromazine metabolites. Toxicology and Applied Pharmacology, 313, 131-137. doi:10.1016/j.taap.2016.10.024Martinez, L. J., Sik, R. H., & Chignell, C. F. (1998). Fluoroquinolone Antimicrobials: Singlet Oxygen, Superoxide and Phototoxicity. Photochemistry and Photobiology, 67(4), 399-403. doi:10.1111/j.1751-1097.1998.tb05217.xFasani, E., Monti, S., Manet, I., Tilocca, F., Pretali, L., Mella, M., & Albini, A. (2009). Inter- and Intramolecular Photochemical Reactions of Fleroxacin. Organic Letters, 11(9), 1875-1878. doi:10.1021/ol900189vBelvedere, A., Boscá, F., Catalfo, A., Cuquerella, M. C., de Guidi, G., & Miranda, M. A. (2002). Type II Guanine Oxidation Photoinduced by the Antibacterial Fluoroquinolone Rufloxacin in Isolated DNA and in 2‘-Deoxyguanosine. Chemical Research in Toxicology, 15(9), 1142-1149. doi:10.1021/tx025530iCuquerella, M. C., Boscá, F., Miranda, M. A., Belvedere, A., Catalfo, A., & de Guidi, G. (2003). Photochemical Properties of Ofloxacin Involved in Oxidative DNA Damage:  A Comparison with Rufloxacin. Chemical Research in Toxicology, 16(4), 562-570. doi:10.1021/tx034006oMonti, S., & Sortino, S. (2002). Laser flash photolysis study of photoionization in fluoroquinolones. Photochemical & Photobiological Sciences, 1(11), 877-881. doi:10.1039/b206750aSeto, Y., Inoue, R., Ochi, M., Gandy, G., Yamada, S., & Onoue, S. (2011). Combined Use of In Vitro Phototoxic Assessments and Cassette Dosing Pharmacokinetic Study for Phototoxicity Characterization of Fluoroquinolones. The AAPS Journal, 13(3). doi:10.1208/s12248-011-9292-7Sauvaigo, S., Douki, T., Odin, F., Caillat, S., Ravanat, J.-L., & Cadet, J. (2001). Analysis of Fluoroquinolone-mediated Photosensitization of 2′-Deoxyguanosine, Calf Thymus and Cellular DNA: Determination of Type-I, Type-II and Triplet–Triplet Energy Transfer Mechanism Contribution¶. Photochemistry and Photobiology, 73(3), 230. doi:10.1562/0031-8655(2001)0732.0.co;2Cuquerella, M. C., Lhiaubet-Vallet, V., Cadet, J., & Miranda, M. A. (2012). Benzophenone Photosensitized DNA Damage. Accounts of Chemical Research, 45(9), 1558-1570. doi:10.1021/ar300054

Niche-Based Screening in Multiple Myeloma Identifies a Kinesin-5 Inhibitor with Improved Selectivity over Hematopoietic Progenitors

SummaryNovel therapeutic approaches are urgently required for multiple myeloma (MM). We used a phenotypic screening approach using co-cultures of MM cells with bone marrow stromal cells to identify compounds that overcome stromal resistance. One such compound, BRD9876, displayed selectivity over normal hematopoietic progenitors and was discovered to be an unusual ATP non-competitive kinesin-5 (Eg5) inhibitor. A novel mutation caused resistance, suggesting a binding site distinct from known Eg5 inhibitors, and BRD9876 inhibited only microtubule-bound Eg5. Eg5 phosphorylation, which increases microtubule binding, uniquely enhanced BRD9876 activity. MM cells have greater phosphorylated Eg5 than hematopoietic cells, consistent with increased vulnerability specifically to BRD9876’s mode of action. Thus, differences in Eg5-microtubule binding between malignant and normal blood cells may be exploited to treat multiple myeloma. Additional steps are required for further therapeutic development, but our results indicate that unbiased chemical biology approaches can identify therapeutic strategies unanticipated by prior knowledge of protein targets