Chemically modified non-antimicrobial tetracyclines are multifunctional drugs against advanced cancers

Prediagnostic Prescription Antibiotics Use and Survival in Patients with Colorectal Cancer: A Swedish National Register-Based Study

BACKGROUND

Antibiotics use is associated with higher colorectal cancer risk, but little is known regarding any potential effects on survival.

METHODS

We conducted a nationwide cohort study, using complete-population data from Swedish national registers between 2005 and 2020, to investigate prediagnostic prescription antibiotics use in relation to survival in colorectal cancer patients.

RESULTS

We identified 36,061 stage I-III and 11,242 stage IV colorectal cancer cases diagnosed between 2010 and 2019. For stage I-III, any antibiotics use (binary yes/no variable) was not associated with overall or cancer-specific survival. Compared with no use, moderate antibiotics use (total 11-60 days) was associated with slightly better cancer-specific survival [adjusted HR (aHR) = 0.93; 95% confidence interval (CI), 0.86-0.99)], whereas very high use (>180 days) was associated with worse survival [overall survival (OS) aHR = 1.42; 95% CI, 1.26-1.60, cancer-specific survival aHR = 1.31; 95% CI, 1.10-1.55]. In analyses by different antibiotic types, although not statistically significant, worse survival outcomes were generally observed across several antibiotics, particularly macrolides and/or lincosamides. In stage IV colorectal cancer, inverse relationships between antibiotics use and survival were noted.

CONCLUSIONS

Overall, our findings do not support any substantial detrimental effects of prediagnostic prescription antibiotics use on cancer-specific survival after colorectal cancer diagnosis, with the possible exception of very high use in stage I-III colorectal cancer. Further investigation is warranted to confirm and understand these results.

IMPACT

Although the study findings require confirmation, physicians probably do not need to factor in prediagnostic prescription antibiotics use in prognosticating patients with colorectal cancer.

Overcoming Drug Resistance in Advanced Prostate Cancer by Drug Repurposing

Prostate cancer (PCa) is the second most common cancer in men. Common treatments include active surveillance, surgery, or radiation. Androgen deprivation therapy and chemotherapy are usually reserved for advanced disease or biochemical recurrence, such as castration-resistant prostate cancer (CRPC), but they are not considered curative because PCa cells eventually develop drug resistance. The latter is achieved through various cellular mechanisms that ultimately circumvent the pharmaceutical’s mode of action. The need for novel therapeutic approaches is necessary under these circumstances. An alternative way to treat PCa is by repurposing of existing drugs that were initially intended for other conditions. By extrapolating the effects of previously approved drugs to the intracellular processes of PCa, treatment options will expand. In addition, drug repurposing is cost-effective and efficient because it utilizes drugs that have already demonstrated safety and efficacy. This review catalogues the drugs that can be repurposed for PCa in preclinical studies as well as clinical trials.

Targeting Mitochondrial Protein Expression as a Future Approach for Cancer Therapy

Extensive metabolic remodeling is a fundamental feature of cancer cells. Although early reports attributed such remodeling to a loss of mitochondrial functions, it is now clear that mitochondria play central roles in cancer development and progression, from energy production to synthesis of macromolecules, from redox modulation to regulation of cell death. Biosynthetic pathways are also heavily affected by the metabolic rewiring, with protein synthesis dysregulation at the hearth of cellular transformation. Accumulating evidence in multiple organisms shows that the metabolic functions of mitochondria are tightly connected to protein synthesis, being assembly and activity of respiratory complexes highly dependent on de novo synthesis of their components. In turn, protein synthesis within the organelle is tightly connected with the cytosolic process. This implies an entire network of interactions and fine-tuned regulations that build up a completely under-estimated level of complexity. We are now only preliminarily beginning to reconstitute such regulatory level in human cells, and to perceive its role in diseases. Indeed, disruption or alterations of these connections trigger conditions of proteotoxic and energetic stress that could be potentially exploited for therapeutic purposes. In this review, we summarize the available literature on the coordinated regulation of mitochondrial and cytosolic mRNA translation, and their effects on the integrity of the mitochondrial proteome and functions. Finally, we highlight the potential held by this topic for future research directions and for the development of innovative therapeutic approaches.

Synthesis of Silver-Doxycycline Complex Nanoparticles and Their Biological Evaluation on MCF-7 Cell Line of the Breast Cancer

In the current study, we aim to evaluate the effect of the combination of silver and doxycycline (silver-doxycycline complex) on the viability of the MCF-7 cell line of the breast in comparison with each of them. The Ag-doxycycline NPs were synthesized using silver nitrate and doxycycline solutions. The synthesized Ag-doxycycline NPs were characterized with several analyses. Ag-doxycycline NPs with a concentration of 25 μM is significantly more effective in decreasing the viability of MCF-7 cells than Ag with the same concentration ( $P<0.05$ ). Doxycycline with a concentration of 6.25 μM also has a more potent effect on the viability of MCF-7 cells than Ag with the same concentration ( $P<0.05$ ). Ag-doxycycline NPs with a 25 μM concentration is more effective than the concentration of 3.125 μM ( $P<0.05$ ). Ag-doxycycline NPs were found to be more effective than AgNPs alone in inhibiting the growth of the MCF-7 cells. Also, the increasing utility of nanotechnology in multiple aspects of medicine can lead to using this technology in the treatment of different types of cancer in the future.

Inhibitors of gelatinases (MMP-2 and MMP-9) for the management of hematological malignancies

Matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) are collectively known as gelatinases whereas MMP-2 is gelatinase-A and MMP-9 is termed as gelatinase-B. Gelatinases and other matrix metalloproteinases (MMPs) have long been associated with solid tumor invasion, metastasis and angiogenesis. However, there is paucity of data available regarding the role of gelatinases in hematological malignancies. Recent studies have shown that gelatinases activities or functions are correlated with hematological malignancies. Strategies for designing more specific gelatinase inhibitors like catalytic (CAT) domain inhibitors and hemopexin (PEX) domain inhibitors as well as signaling pathway based or gelatinase expression inhibitors had been reported against hematologic malignant cells. Several substrate based non-selective to non-substrate based relatively selective synthetic matrix metalloproteinase inhibitors (MMPIs) had been developed. Few MMPIs had reached in clinical trials during the period of 1990s-2000s. Unfortunately the anti-tumor and anti-metastatic efficacies of these MMPIs were not justified with patients having several advanced stage solid tumor cancers in any substantial number of clinical trials. Till date not a single MMPI passed phase III clinical trials designed for advanced metastatic cancers due to adverse events as well as lack of ability to show uniformity in disease prolongation. With the best of our knowledge no clinical trial study has been reported with small molecule synthetic inhibitors against hematological malignancies. This review looks at the outcome of clinical trials of MMPIs for advanced stage solid tumors. This can therefore, act as a learning experience for future development of successful gelatinase inhibitors for the management of hematological malignancies.

Doxycycline Induces Apoptosis of Brucella Suis S2 Strain-Infected HMC3 Microglial Cells by Activating Calreticulin-Dependent JNK/p53 Signaling Pathway

Neurobrucellosis is a chronic complication of human brucellosis that is caused by the presence of Brucella spp in the central nervous system (CNS) and the inflammation play a key role on the pathogenesis. Doxycycline (Dox) is a widely used antibiotic that induces apoptosis of bacteria-infected cells. However, the mechanisms of Brucella inhibition of microglial apoptosis and Dox induction of apoptosis are still poorly understood. In this study, we found that Brucella suis S2 strain (B. suis S2) increased calreticulin (CALR) protein levels and inhbited HMC3 cell apoptosis. Hence, we constructed two HMC3 cell line variants, one with stable overexpression (HMC3-CALR) and one with low expression of CALR (HMC3-sh-CALR). CALR was found to decrease levels of p-JNK and p-p53 proteins, as well as suppress apoptosis in HMC3 cells. These findings suggest that CALR suppresses apoptosis by inhibiting the JNK/p53 signaling pathway. Next, we treated HMC3, HMC3-CALR and HMC3-sh-CALR cell lines with B. suis S2 or Dox. Our results demonstrate that B. suis S2 restrains the JNK/p53 signaling pathway to inhibit HMC3 cell apoptosis via increasing CALR protein expression, while Dox plays the opposite role. Finally, we treated B. suis S2-infected HMC3 cells with Dox. Our results confirm that Dox induces JNK/p53-dependent apoptosis in B. suis S2-infected HMC3 cells through inhibition of CALR protein expression. Taken together, these results reveal that CALR and the JNK/p53 signaling pathway may serve as novel therapeutic targets for treatment of neurobrucellosis.

Repositioning Adequate Antibiotics to Treat/Cure the Coronavirus Disease 2019 (COVID-19): Current Treatments and Future Directions

Aims:

Rational use of antibiotics against the betacoronavirus SARS-CoV-2 responsible for the COVID-19 pandemic.

Objective:

Repositioning and repurposing adequate antibiotics to cure the Coronavirus Disease 2019 (COVID-19).

Background:

It is widely accepted that viral infections such as the SARS-CoV-2 cannot be cured by antibiotics, whereas bacterial infections can. It is because the SARS-CoV-2 virus has no protein synthesis machinery (usually targeted by antibiotics) to produce from its RNA genome, the viral proteins and enzymes essential for its replication and/or for the assembly of viral particles. However, the antibiotics must be capable of inhibiting the ribosomes of the protein synthesis machinery of the SARS-CoV-2-infected human host cells, in order to prevent them from synthesizing new proteins that they do not need, but are needed for the virus to spread. Unfortunately, the only antibiotic capable of selectively inhibiting the human 80S ribosomes, namely cycloheximide, was found to be a poisonous drug for the mammals. Therefore, the only possibility is to search for the antibiotics that are capable of inhibiting both bacterial and eukaryal ribosomes, in order to prevent at the same time the ribosomes of the infected human host cells from synthesizing the proteins and enzymes for the SARS-CoV-2 virus, and those of the eventual opportunistic pathogenic bacteria from developing pneumonia.

Methods:

First, we have used a molecular modeling study involving the tools of the semi-empirical quantum mechanics PM3 method to study the interaction between the cation Zn++ and all the molecules considered as zinc transporters in this report. By this approach, the niche in which Zn++ is located was determined. Such an interaction serves as a shuttle and allows zinc cation to invade endocellular structures in the SARS-CoV-2-infected human host cells. Second, we have measured the poly (U)-dependent poly (Phe) synthesis activity of human 80S ribosomes in the presence of increasing concentrations of four antibiotics of the class of the macrolides, namely erythromycin, azithromycin, clarithromycin and telithromycin. This experiment led us to determine for each macrolide, the half-inhibitory concentration (IC50) that is the concentration of antibiotic corresponding to 50% inhibition of the activity of the human 80S ribosomes. Finally, we have analyzed previously published data from the group of Nierhaus (Berlin) on the competition between the incoming aminoacyl-tRNA and the antibiotic tetracycline for the binding to the ribosomal A-site on the E. coli 70S or rabbit liver 80S ribosomes. This led to the conclusion by the authors that tetracycline most likely binds to corresponding sites in 70S and 80S ribosomes with comparable affinity.

Results:

We propose to reposition the macrolides (azithromycin or erythromycin or others) and tetracyclines for the treatment of COVID-19 patients, on account of the following data gathered in this report. First, these antibiotics are already currently successfully used in medicine in humans and animals. Second, the binding sites of these antibiotics at the upper part of the protein exit tunnel (for the macrolides) and the ribosomal A-site (for tetracyclines) are universally conserved features of the ribosomes in all kingdoms of life. So, these classes of antibiotics are expected to bind to all kinds of ribosomes, the 70S as well as the 80S type, with comparable affinity. Therefore, they are capable of preventing at the same time the ribosomes of the infected human host cells from synthesizing the proteins and enzymes for the SARS-CoV-2 virus, and those of the eventual opportunistic pathogenic bacteria from developing pneumonia. Third, the efficacy assessment of these antibiotics in clinical application consisted of comparing their affinity constants of binding to the human ribosomes with their blood concentration.

For example, in the case of azithromycin, the amount of antibiotic administered to COVID-19 patients was 100 μg/ml of circulating blood, which is 43 times superior to the half-inhibitory concentration (IC50 or KIa of 2.3 μg/ml), the concentration of azithromycin corresponding to 50% inhibition of the activity of the human 80S ribosomes. Fourth, zinc cations were previously shown to be a strong antiviral agent, while all the macrolides and tetracyclines that we propose for repurposing or repositioning to cure the COVID-19 are shown in the present report to form Zn++-antibiotic complex and behave as efficient zinc transporters into the SARS-CoV-2-infected host cells.

Conclusion:

The macrolides (azithromycin or erythromycin or others) and tetracyclines selected for repositioning and repurposing to cure COVID-19 are candidates as specific and effective therapeutic drugs available for the coronavirus disease. We propose to combat the current COVID-19 pandemic with azithromycin or erythromycin (or equivalent) alone or in combination with tetracycline (or equivalent) in the presence of Zn++(SO4--). Taking into account the fact that azithromycin had been shown to be effective in treating viral infections such as papillomaviruses in humans and dogs, we conclude that the statement “no antibiotic for viral infections !” is not relevant for all the clinically approved classes of antibiotics, because selective antibiotics such as the universal antibiotics described in the present report are capable of exhibiting antiviral activities through specific interactions with the human 80S ribosomes of infected host cells. As a conclusion, even though the clinical and experimental data presented here do not suggest virucidal activity of azithromycin-zinc or tetracycline-zinc complexes, they do indicate that when administered simultaneously at the onset of first signs of COVID-19, the most common symptoms being fatigue, fever, dry cough, headache, sore throat, muscle pain or shortness of breath, azithromycin (or tetracycline) and zinc cations are capable of inhibiting ribosomal activity of SARS-CoV-2-infected human cells. This results in blocking protein and enzyme synthesis vital for viral RNA replication and for assembly of viral particles. Early treatment allows both reductions of viremia as well as stabilizing symptoms. The major advantage of this therapeutic strategy is avoiding prolonged clinical COVID-19 disease with contingent worsening of illness and subsequent need for intensive care. Prolonged COVID-19 illness is the major downfall of the present pandemic, returning to normal being long, difficult, and sometimes impossible.

CMT-308, a Nonantimicrobial Chemically-Modified Tetracycline, Exhibits Anti-Melanogenic Activity by Suppression of Melanosome Export

CMT-308 is a nonantimicrobial chemically-modified tetracycline (CMT), which we have previously shown exhibits antifungal activity and pleiotropic anti-inflammatory activities, including inhibition of the enzymatic activity of matrix metalloproteinases (MMPs). Based on its chemical structure, we hypothesized that CMT-308 could inhibit melanogenesis and might be a candidate for the treatment of skin hyperpigmentation disorders which occur due to unregulated melanin biosynthesis and/or transport. CMT-308 was first studied for any effects on activity of the enzyme tyrosinase in vitro using a purified preparation of mushroom tyrosinase; the mode of inhibition of the soluble fungal enzyme was evaluated by Lineweaver-Burk and Dixon plots as well as by non-linear least squares fitting. Next, the effects of CMT-308 were tested in mammalian cell cultures using B16F10 mouse melanoma cells and further validated in darkly-pigmented human melanocytes (HEMn-DP). Our results showed that micromolar concentrations of CMT-308 inhibited mushroom tyrosinase enzyme activity, using the first two substrates in the melanogenesis pathway (l-tyrosine and l-3,4-dihydroxyphenylalanine (l-DOPA)); CMT-308 inhibited mushroom tyrosinase primarily via a mixed mode of inhibition, with the major contribution from a competitive mode. In B16F10 cell cultures, CMT-308 (10 µM) significantly diminished total melanin levels with a selective reduction of extracellular melanin levels, under both basal and hormone-stimulated conditions without any cytotoxicity over a duration of 72 h. Studies of potential mechanisms of inhibition of melanogenesis in B16F10 cells showed that, in mammalian cells, CMT-308 did not inhibit intracellular tyrosinase activity or the activity of α-glucosidase, an enzyme that regulates maturation of tyrosinase. However, CMT-308 suppressed MITF protein expression in B16F10 cells and showed copper chelating activity and antioxidant activity in a cell-free system. The significantly lower extracellular melanin levels obtained at 10 µM indicate that CMT-308’s anti-melanogenic action may be attributed to a selective inhibition of melanosome export with the perinuclear aggregation of melanosomes, rather than a direct effect on the tyrosinase-catalyzed steps in melanin biosynthesis. These results were validated in HEMn-DP cells where CMT-308 suppressed dendricity in a fully reversible manner without affecting intracellular melanin synthesis. Furthermore, the capacity of CMT-308 to inhibit melanosome export was retained in cocultures of HEMn-DP and HaCaT. In summary, our results offer promise for therapeutic strategies to combat the effects of hyperpigmentation by use of CMT-308 at low micromolar concentrations.

Lymecycline reverses acquired EGFR-TKI resistance in non-small-cell lung cancer by targeting GRB2

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) were first-line treatments for NSCLC patients with EGFR-mutations. However, about 30 % of responders relapsed within six months because of acquired resistance. In this study, we used Connectivity Map (CMap) to discover a drug capable of reversing acquired EGFR-TKIs resistance. To investigate Lymecycline's ability to reverse acquired EGFR-TKIs resistance, two Icotinib resistant cell lines were constructed. Lymecycline's ability to suppress the proliferation of Icotinib resistant cells in vitro and in vivo was then evaluated. Molecular targets were predicted using network pharmacology and used to identify the molecular mechanism. Growth factor receptor-bound protein 2 (GRB2) is an EGFR-binding adaptor protein essential for EGFR phosphorylation and regulation of AKT/ERK/STAT3 signaling pathways. Lymecycline targeted GRB2 and inhibited the resistance of the cell cycle to EGFR-TKI, arresting disease progression and inducing apoptosis in cancer cells. Combined Lymecycline and Icotinib treatment produced a synergistic effect and induced apoptosis in HCC827R5 and PC9R10 cells. Cell proliferation in resistant cancer cells was significantly inhibited by the combined Lymecycline and Icotinib treatment in mouse models. Lymecycline inhibited the resistance of the cell cycle to EGFR-TKI and induced apoptosis in NSCLC by inhibiting EGFR phosphorylation and GRB2-mediated AKT/ERK/STAT3 signaling pathways. This provided strong support that Lymecycline when combined with EGFR targeting drugs, enhanced the efficacy of treatments for drug-resistant NSCLC.

Periodontal therapeutics: Current host-modulation agents and future directions

With the recognition in the 1960s and 1970s of the periodontopathic importance of the microbial biofilm and its specific anaerobic microorganisms, periodontitis was treated as an infectious disease (more recently, as a dysbiosis). Subsequently, in the 1980s, host-response mechanisms were identified as the mediators of the destruction of the collagen-rich periodontal tissues (gingiva, periodontal ligament, alveolar bone), and the periodontopathogens were now regarded as the "trigger" of the inflammatory/collagenolytic response that characterizes actively destructive periodontitis. Also at this time a new pharmacologic strategy emerged, entitled "host-modulation therapy", based on 2 major findings: (1) that the ability of tetracycline antibiotics to inhibit periodontal breakdown was due (in large part) to their previously unrecognized ability to inhibit the host-derived matrix metalloproteinases (notably, the collagenases, gelatinases, macrophage metalloelastase), and by mechanisms unrelated to the antimicrobial properties of these medications; and (2) that nonsteroidal anti-inflammatory drugs, such as flurbiprofen, again by nonantimicrobial mechanisms, could reduce the severity of periodontitis (however, the adverse effects of long-term therapy precluded their development as safe and effective host-modulatory agents). Additional mechanistic studies resulted in the development of novel nonantimicrobial formulations (Periostat® [now generic] and Oracea®) and compositions of tetracyclines (notably chemically modified tetracycline-3) as host-modulator drugs for periodontitis, arthritis, cardiovascular and pulmonary diseases, cancer, and, more recently, for local and systemic bone loss in postmenopausal women. Identification of the cation-binding active site in the tetraphenolic chemically modified tetracycline molecules drove the development of a new category of matrix metalloproteinase-inhibitor compounds, with a similar active site, the biphenolic chemically modified curcumins. A lead compound, chemically modified curcumin 2.24, has demonstrated safety and efficacy in vitro, in cell culture, and in vivo in mouse, rat, rabbit, and dog models of disease. In conclusion, novel host-modulation compounds have shown significant promise as adjuncts to traditional local therapy in the clinical management of periodontal disease; appear to reduce systemic complications of this all-too-common "inflammatory/collagenolytic" disease; and Oracea® is now commonly prescribed for inflammatory dermatologic diseases.

Targeting Mammalian Translational Inhibition with Tetracyclines

In this issue of Cell Chemical Biology, Mortison et al. (2018) report an in-depth mechanistic study of targets of two different tetracyclines in mammalian cells. Unbiased chemoproteomics and RNA sequence mapping help identify specific ribosomal substructures bound by tetracyclines, providing insight into the therapeutic potential for tetracyclines in many diseases.

Curcuma raktakanda Induces Apoptosis and Suppresses Migration in Cancer Cells: Role of Reactive Oxygen Species

Although over 100 species of Curcuma are reported, only Curcuma longa is extensively studied. Curcuma raktakanda, a poorly studied species, is most commonly distributed in the Kerala state of India. For the first time, we examined the efficacy of different fractions (acetone, hexane, and ethyl acetate) of C. raktakanda against glioma, cervical, and breast cancer cell lines. As determined by mitochondrial reductase activity assay, the viability of cancer cells was decreased in a concentration-dependent manner by the three fractions. The half maximal inhibitory concentration (IC-50) values after the treatment of C-6 glioma cells for 48 h was found to be 32.97 µg/mL (acetone extract), 40.63 µg/mL (hexane extract), and 51.65 µg/mL (ethyl acetate extract). Of the three fractions, the acetone fraction was more effective. The long-term colony formation of cancer cells was significantly suppressed by the acetone fraction. Analyses using DAPI (4',6-diamidino-2-phenylindole) staining, AO/PI (acridine orange/propidium iodide) staining, DNA laddering, and sub-G1 population revealed that the acetone extract induced apoptosis in glioma cells. The extract induced reactive oxygen species generation and suppressed the expression of cell survival proteins. The migration of cancer cells was also suppressed by the acetone extract. The gas chromatography-mass spectrometry (GC-MS) analysis indicated that tetracontane, dotriacontane, hexatriacontane, pentacosane, hexacosane, and eicosane are the major components in the acetone extract. Collectively, the extract from C. raktakanda exhibited anti-carcinogenic activities in cancer cells. We are exploring whether the phytoconstituents, individually, or collectively contribute to the anti-cancer activities of C. raktakanda.

Immunomodulatory tetracyclines shape the intestinal inflammatory response inducing mucosal healing and resolution

BACKGROUND AND PURPOSE

Immunomodulatory tetracyclines are well-characterized drugs with a pharmacological potential beyond their antibiotic properties. Specifically, minocycline and doxycycline have shown beneficial effects in experimental colitis, although pro-inflammatory actions have also been described in macrophages. Therefore, we aimed to characterize the mechanism behind their effect in acute intestinal inflammation.

EXPERIMENTAL APPROACH

A comparative pharmacological study was initially used to elucidate the most relevant actions of immunomodulatory tetracyclines: doxycycline, minocycline and tigecycline; other antibiotic or immunomodulatory drugs were assessed in bone marrow-derived macrophages and in dextran sodium sulfate (DSS)-induced mouse colitis, where different barrier markers, inflammatory mediators, microRNAs, TLRs, and the gut microbiota composition were evaluated. The sequential immune events that mediate the intestinal anti-inflammatory effect of minocycline in DSS-colitis were then characterized.

KEY RESULTS

Novel immunomodulatory activity of tetracyclines was identifed; they potentiated the innate immune response and enhanced resolution of inflammation. This is also the first report describing the intestinal anti-inflammatory effect of tigecycline. A minor therapeutic benefit seems to derive from their antibiotic properties. Conversely, immunomodulatory tetracyclines potentiated macrophage cytokine release in vitro, and while improving mucosal recovery in colitic mice, they up-regulated Ccl2, miR-142, miR-375 and Tlr4. In particular, minocycline initially enhanced IL-1β, IL-6, IL-22, GM-CSF and IL-4 colonic production and monocyte recruitment to the intestine, subsequently increasing Ly6C^- MHCII⁺ macrophages, Tregs and type 2 intestinal immune responses.

CONCLUSIONS AND IMPLICATIONS

Immunomodulatory tetracyclines potentiate protective immune pathways leading to mucosal healing and resolution, representing a promising drug reposition strategy for the treatment of intestinal inflammation.

Tetracyclines Modify Translation by Targeting Key Human rRNA Substructures

Apart from their antimicrobial properties, tetracyclines demonstrate clinically validated effects in the amelioration of pathological inflammation and human cancer. Delineation of the target(s) and mechanism(s) responsible for these effects, however, has remained elusive. Here, employing quantitative mass spectrometry-based proteomics, we identified human 80S ribosomes as targets of the tetracyclines Col-3 and doxycycline. We then developed in-cell click selective crosslinking with RNA sequence profiling (icCL-seq) to map binding sites for these tetracyclines on key human rRNA substructures at nucleotide resolution. Importantly, we found that structurally and phenotypically variant tetracycline analogs could chemically discriminate these rRNA binding sites. We also found that tetracyclines both subtly modify human ribosomal translation and selectively activate the cellular integrated stress response (ISR). Together, the data reveal that targeting of specific rRNA substructures, activation of the ISR, and inhibition of translation are correlated with the anti-proliferative properties of tetracyclines in human cancer cell lines.

Mitochondria as oncotarget: a comparison between the tetracycline analogs doxycycline and COL-3

Tetracyclines have anticancer properties in addition to their well-known antibacterial properties. It has been proposed that tetracyclines slow metastasis and angiogenesis through inhibition of matrix metalloproteinases. However, we believe that the anticancer effect of tetracyclines is due to their inhibition of mitochondrial protein synthesis, resulting in a decrease of the mitochondrial energy generating capacity. Several groups have developed analogs that are void of antibacterial action. An example is COL-3, which is currently tested for its anticancer effects in clinical trials. We have undertaken a comparative study of the tetracycline analogs COL-3 and doxycycline, which has an antibacterial function, to further investigate the role of the mitochondrial energy generating capacity in the anticancer mechanism and, thereby, evaluate the usefulness of mitochondria as an oncotarget. Our experiments with cultures of the human A549, COLO357 and HT29 cancer cells and fibroblasts indicated that COL-3 is significantly more cytotoxic than doxycycline. Mitochondrial translation assays demonstrated that COL-3 has retained its inhibitory effect on mitochondrial protein synthesis. Both drugs caused a severe decrease in the levels of mitochondrially encoded cytochrome-c oxidase subunits and cytochrome-c oxidase activity. In addition, COL-3 produced a marked drop in the level of nuclear-encoded succinate dehydrogenase subunit A and citrate synthase activity, indicating that COL-3 has multiple inhibitory effects. Contrary to COL-3, the anticancer action of doxycycline appears to be based specifically on inhibition of mitochondrial protein synthesis, which is thought to affect rapidly proliferating cancer cells more than healthy tissue. Doxycycline is likely to cause less side effects that COL-3.

Drug Repositioning for Effective Prostate Cancer Treatment

Drug repositioning has gained attention from both academia and pharmaceutical companies as an auxiliary process to conventional drug discovery. Chemotherapeutic agents have notorious adverse effects that drastically reduce the life quality of cancer patients so drug repositioning is a promising strategy to identify non-cancer drugs which have anti-cancer activity as well as tolerable adverse effects for human health. There are various strategies for discovery and validation of repurposed drugs. In this review, 25 repurposed drug candidates are presented as result of different strategies, 15 of which are already under clinical investigation for treatment of prostate cancer (PCa). To date, zoledronic acid is the only repurposed, clinically used, and approved non-cancer drug for PCa. Anti-cancer activities of existing drugs presented in this review cover diverse and also known mechanisms such as inhibition of mTOR and VEGFR2 signaling, inhibition of PI3K/Akt signaling, COX and selective COX-2 inhibition, NF-κB inhibition, Wnt/β-Catenin pathway inhibition, DNMT1 inhibition, and GSK-3β inhibition. In addition to monotherapy option, combination therapy with current anti-cancer drugs may also increase drug efficacy and reduce adverse effects. Thus, drug repositioning may become a key approach for drug discovery in terms of time- and cost-efficiency comparing to conventional drug discovery and development process.

Matrix Metalloproteinases in Bone Resorption, Remodeling, and Repair

Matrix metalloproteinases (MMPs) are the major protease family responsible for the cleavage of the matrisome (global composition of the extracellular matrix (ECM) proteome) and proteins unrelated to the ECM, generating bioactive molecules. These proteins drive ECM remodeling, in association with tissue-specific and cell-anchored inhibitors (TIMPs and RECK, respectively). In the bone, the ECM mediates cell adhesion, mechanotransduction, nucleation of mineralization, and the immobilization of growth factors to protect them from damage or degradation. Since the first description of an MMP in bone tissue, many other MMPs have been identified, as well as their inhibitors. Numerous functions have been assigned to these proteins, including osteoblast/osteocyte differentiation, bone formation, solubilization of the osteoid during bone resorption, osteoclast recruitment and migration, and as a coupling factor in bone remodeling under physiological conditions. In turn, a number of pathologies, associated with imbalanced bone remodeling, arise mainly from MMP overexpression and abnormalities of the ECM, leading to bone osteolysis or bone formation. In this review, we will discuss the functions of MMPs and their inhibitors in bone cells, during bone remodeling, pathological bone resorption (osteoporosis and bone metastasis), bone repair/regeneration, and emergent roles in bone bioengineering.

Glutamate Transport System as a Novel Therapeutic Target in Chronic Pain: Molecular Mechanisms and Pharmacology

The vast majority of peripheral neurons sensing noxious stimuli and conducting pain signals to the dorsal horn of the spinal cord utilize glutamate as a chemical transmitter of excitation. High-affinity glutamate transporter subtypes GLAST/EAAT1, GLT1/EAAT2, EAAC1/EAAT3, and EAAT4, differentially expressed on sensory neurons, postsynaptic spinal interneurons, and neighboring glia, ensure fine modulation of glutamate neurotransmission in the spinal cord. The glutamate transport system seems to play important roles in molecular mechanisms underlying chronic pain and analgesia. Downregulation of glutamate transporters (GluTs) often precedes or occurs simultaneously with development of hypersensitivity to thermal or tactile stimuli in various models of chronic pain. Moreover, antisense knockdown or pharmacological inhibition of these membrane proteins can induce or aggravate pain. In contrast, upregulation of GluTs by positive pharmacological modulators or by viral gene transfer to the spinal cord can reverse the development of such pathological hypersensitivity. Furthermore, some multi-target drugs displaying analgesic properties (e.g., tricyclic antidepressant amitriptyline, riluzole, anticonvulsant valproate, tetracycline antibiotic minocycline, β-lactam antibiotic ceftriaxone and its structural analog devoid of antibacterial activity, clavulanic acid) can significantly increase the spinal glutamate uptake. Thus, mounting evidence points at GluTs as prospective therapeutic target for chronic pain treatment. However, design and development of new analgesics based on the modulation of glutamate uptake will require more precise knowledge of molecular mechanisms underlying physiological or aberrant functioning of this transport system in the spinal cord.

Collagenopathies-Implications for Abdominal Wall Reconstruction: A Systematic Review

Background:

The etiology of hernia formation is strongly debated and includes mechanical strain, prior surgical intervention, abnormal embryologic development, and increased intraabdominal pressure. Although the most common inciting cause in ventral hernias is previous abdominal surgery, many other factors contribute. We explore this etiology through an examination of the current literature and existing evidence on patients with collagen vascular diseases, such as Ehlers–Danlos syndrome.

Methods:

A systematic review of the published literature was performed of all available Spanish and English language PubMed and Cochrane articles containing the key words “collagenopathies,” “collagenopathy,” “Ehlers-Danlos,” “ventral hernia,” and “hernia.”

Results:

Three hundred fifty-two articles were identified in the preliminary search. After review, 61 articles were included in the final review.

Conclusions:

Multiple authors suggest a qualitative or quantitative defect in collagen formation as a common factor in hernia formation. High-level clinical data clearly linking collagenopathies and hernia formation are lacking. However, a trend in pathologic studies suggests a link between abnormal collagen production and/or processing that is likely associated with hernia development.

Doxycycline reverses epithelial-to-mesenchymal transition and suppresses the proliferation and metastasis of lung cancer cells

The gelatinase inhibitor doxycycline is the prototypical antitumor antibiotic. We investigated the effects of doxycycline on the migration, invasion, and metastasis of human lung cancer cell lines and in a mouse model. We also measured the effect of doxycycline on the transcription of epithelial-mesenchymal transition (EMT) markers, and used immunohistochemistry to determine whether EMT reversal was associated with doxycycline inhibition. Doxycycline dose-dependently inhibited proliferation, migration, and invasion of NCI-H446 human small cell lung cancer cells. It also suppressed tumor growth from NCI-H446 and A549 lung cancer cell xenografts without altering body weight, inhibited Lewis lung carcinoma cell migration, and prolonged survival. The activities of the transcription factors Twist1/2, SNAI1/2, AP1, NF-κB, and Stat3 were suppressed by doxycycline, which reversed EMT and inhibited signal transduction, thereby suppressing tumor growth and metastasis. Our data demonstrate functional targeting of transcription factors by doxycycline to reverse EMT and suppress tumor proliferation and metastasis. Thus, doxycycline selectively targets malignant tumors and reduces its metastatic potential with less cytotoxicity in lung cancer patients.

Novel mechanisms involving chemically modified tetracycline 3 cytotoxicity

Chemically modified tetracycline 3 (CMT-3) is a potential anticancer drug because of its retained matrix metalloproteinases inhibitory property. In the present study,we showed that CMT-3 significantly inhibited the growth and proliferation of human hepatocellular carcinoma HepG2 cells. Novel mechanisms including increased intracellular autophagy level and high-mobility group box 1 (HMGB1)release were involved. In addition, a major Danshen ingredient, tanshinone IIA sodium sulfonate (TSN-SS),significantly increased the cytotoxic effects of CMT-3 in HepG2 cells. Combining CMT-3 with TSN-SS led to enhanced accumulation of endogenous LC3-II, but reduced HMGB1 cytoplasmic translocation. Altogether, these findings suggest that autophagy and HMGB1 release may play important roles in the anticancer effect of CMT-3. As an ovel candidate for cancer therapy, CMT-3 may be used in combination with TSN-SS, which possibly facilitates the execution of a death signal (e.g. autophagy) and prevents the survival of an inducer (e.g. HMGB1 cytoplasmic translocation), thus improving its therapeutic effect.

Human VDAC isoforms differ in their capability to interact with minocycline and to contribute to its cytoprotective activity

It has been previously demonstrated that cytoprotective activity displayed by minocycline in the case of the yeast Saccharomyces cerevisiae cells pretreated with H2O2 requires the presence of functional VDAC (YVDAC1). Thus, we decided to transform YVDAC1-depleted yeast cells (Δpor1 cells) with plasmids expressing human VDAC isoforms (HVDAC1, HVDAC2, HVDAC3) to estimate their involvement in the minocycline cytoprotective effect. We observed that only expression of HVDAC3 in Δpor1 cells provided minocycline-mediated cytoprotection against H2O2 although all human isoforms are functional in Δpor1 cells. The observation appears to be important for on-going discussion concerning VDAC isoform roles in mitochondria and cell functioning.

Evaluation of the effects of two different bone resorption inhibitors on osteoclast numbers and activity: An animal study

Background:

The aim of this study was to evaluate the effects of bone resorption inhibitors, doxycycline (DOX) and erythromycin (EM), on osseous wound healing in rat alveolar socket.

Materials and Methods:

In this randomized controlled trial, 45 8–10-week-old male Wistar rats had their maxillary right molar extracted. They were divided into three groups of 15. In Group 1 normal saline, Group 2 DOX, and Group 3 EM were administered at the doses of 5 ml/kg/day, 5 mg/kg/day, and 2 mg/kg/day, respectively, for 7 consecutive days. The rats were sacrificed 7, 14, and 21 days after surgery. Real-time polymerase chain reaction was employed to evaluate the mRNA expression of receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) and immunohistochemical staining for tartrate-resistant acid phosphatase (TRAP) to determine osteoclasts. The data were analyzed by one-way analysis of variance followed by Tukey's post hoc test using SPSS version 20. Significant level was set at 0.05.

Results:

The results showed that when drug-treated groups compared to control groups, RANKL gene expression significantly decreased, TRAP⁺ cells decreased on day 7. The RANKL/OPG ratios in the first two weeks in the test groups were significantly lower than the control group. There was no significant difference in the studied indices between DOX and EM groups.

Conclusion:

Following administration of DOX and EM, the number of osteoclasts and RANKL/OPG ratio decreased suggesting their anti-osteoclastogenesis activity. These two drugs have no advantage over each other in increasing the bone formation.

The Regulation of Matrix Metalloproteinase Expression and the Role of Discoidin Domain Receptor 1/2 Signalling in Zoledronate-treated PC3 Cells

Discoidin Domain Receptors (DDR1/DDR2) are tyrosine kinase receptors which are activated by collagen. DDR signalling regulates cell migration, proliferation, apoptosis and matrix metalloproteinase (MMP) production. MMPs degrade extracellular matrix (ECM) and play essential role in tumor growth, invasion and metastasis. Nitrogen-containing bisphosphonates (N-BPs) which strongly inhibit osteoclastic activity are commonly used for osteoporosis treatment. They also have MMP inhibitory effect. In this study, we aimed to investigate the effects of zoledronate in PC3 cells and the possible role of DDR signalling and downstream pathways in these inhibitory effects.

We studied messenger RNA (mRNA) and protein expressions of MMP-2,-9,-8, DDR1/DDR2 type I procollagen (TIP) and mRNA levels of PCA-1, MMP-13 and DDR-initiated signalling pathway players including K-Ras oncogene, ERK1, JNK1, p38, AKT-1 and BCLX in PC3 cells in the presence or absence of zoledronate (10-100 μM) for 2-3 days.

Zoledronate (100 μM) down-regulated DDR1/ DDR2, TIP mRNAs but did not change MMP-13 (collagenase-3) mRNA. However, zoledronate up-regulated MMP-8 (collagenase-2) mRNA. Zoledronate also inhibited mRNA expressions of K-Ras, ERK1, AKT-1, BCLX and PCA-1; but did not change JNK1, p38 mRNA levels. Zoledronate (100 μM) supressed DDR1/DDR2, TIP expressions; and gelatinase (MMP-2/MMP-9) expressions/activities. Conversely, zoledronate up-regulated MMP-8 expression in PC3 cells.

Zoledronate down-regulates MMP-2/-9 expressions in PC3 prostate cancer cells. DDR1/DDR2 signalling and DDR-initiated downstream Ras/Raf/ERK and PI3K/AKT pathways may at least partially responsible for MMP inhibitory effect of zoledronate.

Clonal expansion of T cells in abdominal aortic aneurysm: a role for doxycycline as drug of choice?

Most reported studies with animal models of abdominal aortic aneurysm (AAA) and several studies with patients have suggested that doxycycline favourably modifies AAA; however, a recent large long-term clinical trial found that doxycycline did not limit aneurysm growth. Thus, there is currently no convincing evidence that doxycycline reduces AAA expansion. Here, we critically review the available experimental and clinical information about the effects of doxycycline when used as a pharmacological treatment for AAA. The view that AAA can be considered an autoimmune disease and the observation that AAA tissue shows clonal expansion of T cells is placed in the light of the well-known inhibition of mitochondrial protein synthesis by doxycycline. In T cell leukaemia animal models, this inhibitory effect of the antibiotic has been shown to impede T cell proliferation, resulting in complete tumour eradication. We suggest that the available evidence of doxycycline action on AAA is erroneously ascribed to its inhibition of matrix metalloproteinases (MMPs) by competitive binding of the zinc ion co-factor. Although competitive binding may explain the inhibition of proteolytic activity, it does not explain the observed decreases of MMP mRNA levels. We propose that the observed effects of doxycycline are secondary to inhibition of mitochondrial protein synthesis. Provided that serum doxycycline levels are kept at adequate levels, the inhibition will result in a proliferation arrest, especially of clonally expanding T cells. This, in turn, leads to the decrease of proinflammatory cytokines that are normally generated by these cells. The drastic change in cell type composition may explain the changes in MMP mRNA and protein levels in the tissue samples.

Non-anti-infective effects of antimicrobials and their clinical applications: a review

Antimicrobial agents are undoubtedly one of the key advances in the history of modern medicine and infectious diseases, improving the clinical outcomes of infection owing to their inhibitory effects on microbial growth. However, many antimicrobial agents also have biological activities stemming from their interactions with host receptors and effects on host inflammatory responses and other human or bacterial cellular biological pathways. These result in clinical uses of antimicrobial drugs that are distinct from their direct bacteriostatic or bactericidal properties. We reviewed the published literature regarding non-anti-infective therapeutic properties and proposed clinical applications of selected antimicrobials, specifically, macrolides, tetracyclines, sulfonamides, and ketoconazole. The clinical applications reviewed were varied, and we focused on uses that were clinically relevant (in terms of importance and burden of disease) and where published evidence exists. Such uses include chronic inflammatory pulmonary and skin disorders, chronic periodontitis, gastrointestinal dysmotility, rheumatoid arthritis, and cancer. Most of these potential therapeutic uses are not Food and Drug Administration approved. Clinicians need to weigh the use of antimicrobial agents for their non-anti-infective benefits, considering potential adverse effects and long-term effect on microbial resistance.

Minocycline: far beyond an antibiotic

Minocycline is a second-generation, semi-synthetic tetracycline that has been in therapeutic use for over 30 years because of its antibiotic properties against both gram-positive and gram-negative bacteria. It is mainly used in the treatment of acne vulgaris and some sexually transmitted diseases. Recently, it has been reported that tetracyclines can exert a variety of biological actions that are independent of their anti-microbial activity, including anti-inflammatory and anti-apoptotic activities, and inhibition of proteolysis, angiogenesis and tumour metastasis. These findings specifically concern to minocycline as it has recently been found to have multiple non-antibiotic biological effects that are beneficial in experimental models of various diseases with an inflammatory basis, including dermatitis, periodontitis, atherosclerosis and autoimmune disorders such as rheumatoid arthritis and inflammatory bowel disease. Of note, minocycline has also emerged as the most effective tetracycline derivative at providing neuroprotection. This effect has been confirmed in experimental models of ischaemia, traumatic brain injury and neuropathic pain, and of several neurodegenerative conditions including Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, Alzheimer's disease, multiple sclerosis and spinal cord injury. Moreover, other pre-clinical studies have shown its ability to inhibit malignant cell growth and activation and replication of human immunodeficiency virus, and to prevent bone resorption. Considering the above-mentioned findings, this review will cover the most important topics in the pharmacology of minocycline to date, supporting its evaluation as a new therapeutic approach for many of the diseases described herein.

Mitochondrial dysregulation and protection in cisplatin nephrotoxicity

Nephrotoxicity is a major side effect of cisplatin in chemotherapy. Pathologically, cisplatin nephrotoxicity is characterized by cell injury and death in renal tubules. The research in the past decade has gained significant understanding of the cellular and molecular mechanisms of tubular cell death, revealing a central role of mitochondrial dysregulation. The pathological changes in mitochondria in cisplatin nephrotoxicity are mainly triggered by DNA damage response, pro-apoptotic protein attack, disruption of mitochondrial dynamics, and oxidative stress. As such, inhibitory strategies targeting these cytotoxic events may provide renal protection. Nonetheless, ideal approaches for renoprotection should not only protect kidneys but also enhance the anticancer efficacy of cisplatin in chemotherapy.

Striking growth-inhibitory effects of minocycline on human prostate cancer cell lines

OBJECTIVE

To elucidate a hypothetical link between retinoic acid (RA) signaling and minocycline for targeting prostate carcinoma (PCA). RA signaling has been implicated in growth-inhibition of malignant PCA, and intracellular RA homeostasis has been investigated as a potential therapeutic target. Minocycline is a tetracycline antibiotic with pleiotropic actions in many tissues and reaches comparably high levels in human prostate tissue. Interestingly, minocycline exhibits the rare side effect of a pseudotumor cerebri, which is otherwise known to occur from vitamin A intoxication or in retinoid therapy. Therefore, we hypothesized minocycline to putatively interact with intracellular RA homeostasis in PCA.

METHODS

Using LN-CAP, DU-145, and PC-3 cell lines, effects of minocycline on microsomal RA metabolism and on cell growth were assessed in vitro.

RESULTS

Minocycline was identified to potently inhibit cell growth, at concentrations within the range of tissue levels readily reached under standard therapeutic conditions. In vitro inhibition experiments revealed inhibition of RA breakdown, yet only at comparably high concentrations of minocycline. Using all trans-RA, RA metabolism inhibitor liarozole, and different retinoid receptor antagonists, the putative RA-dependent effects of minocycline were further evaluated and confirmed to be independent of RA signaling.

CONCLUSION

Our findings add to the growing body of evidence for the many pleiotropic actions of minocycline. In view of the striking effects of minocycline on cell growth in PCA cell lines in vitro and its relatively safe side effect profile, the use of minocycline for targeting PCA should be timely clinically evaluated.

Nanotechnology approaches for personalized treatment of multidrug resistant cancers

The efficacy of chemotherapy is substantially limited by the resistance of cancer cells to anticancer drugs that fluctuates significantly in different patients. Under identical chemotherapeutic protocols, some patients may receive relatively ineffective doses of anticancer agents while other individuals obtain excessive amounts of drugs that induce severe adverse side effects on healthy tissues. The current review is focused on an individualized selection of drugs and targets to suppress multidrug resistance. Such selection is based on the molecular characteristics of a tumor from an individual patient that can potentially improve the treatment outcome and bring us closer to an era of personalized medicine.

Inhibitory impacts of chemically modified tetracycline-3 and underlying mechanism in human cervical cancer cells

Chemically modified tetracyclines (CMTs) have been rationally designed from tetracyclines. The CMTs that show the antimicrobial properties are eliminated, whereas matrix metalloproteinase inhibitory properties are retained. Interestingly, CMT-3 (COL-3, by eliminating the dimethylamino, methyl, and hydroxyl functionalities on the basic tetracycline structure), one of the CMTs, has shown strong anticancer activity. In this study, we found that CMT-3 showed dose-dependent and time-dependent cytotoxicity in HeLa and Siha cells, two human cervical cancer cell lines. HeLa cells were more sensitive to CMT-3 compared with Siha cells. The antiproliferation potential of CMT-3 was associated with the mitochondrial apoptosis pathway, increasing reactive oxygen species level, and proapoptosis protein (e.g. caspase-3) expression, but decreasing antiapoptosis protein expression (e.g. Bcl-2). N-acetylcysteine (a reactive oxygen species inhibitor) and Z-LEHD-FMK significantly reduced or blocked the apoptosis event resulting from cytotoxic effect of CMT-3. CMT-3 also induced G0/G1 phase arrest with the reduction of cell cycle regulatory protein cyclin E and the translocation of NF-κB from the cytoplasm to the nucleus. Our findings provide the important foundation for further investigation of the underlying mechanism for the anticancer activity of CMT-3 and the potential application of CMT-3 as a new therapeutic candidate for clinical cervical cancer therapy.

Biotic acts of antibiotics

Biological functions of antibiotics are not limited to killing. The most likely function of antibiotics in natural microbial ecosystems is signaling. Does this signaling function of antibiotics also extend to the eukaryotic – in particular mammalian – cells? In this review, the host modulating properties of three classes of antibiotics (macrolides, tetracyclines, and β-lactams) will be briefly discussed. Antibiotics can be effective in treatment of a broad spectrum of diseases and pathological conditions other than those of infectious etiology and, in this capacity, may find widespread applications beyond the intended antimicrobial use. This use, however, should not compromise the primary function antibiotics are used for. The biological background for this inter-kingdom signaling is also discussed.

Cancer drug discovery by repurposing: teaching new tricks to old dogs

Progressively increasing failure rates, high cost, poor bioavailability, poor safety, limited efficacy, and a lengthy design and testing process associated with cancer drug development have necessitated alternative approaches to drug discovery. Exploring established non-cancer drugs for anticancer activity provides an opportunity rapidly to advance therapeutic strategies into clinical trials. The impetus for development of cancer therapeutics from non-cancer drugs stems from the fact that different diseases share common molecular pathways and targets in the cell. Common molecular origins of diverse diseases have been discovered through advancements in genomics, proteomics, and informatics technologies, as well as through the development of analytical tools that allow researchers simultaneously to screen large numbers of existing drugs against a particular disease target. Thus, drugs originally identified as antitussive, sedative, analgesic, antipyretic, antiarthritic, anesthetic, antidiabetic, muscle relaxant, immunosuppressant, antibiotic, antiepileptic, cardioprotective, antihypertensive, erectile function enhancing, or angina relieving are being repurposed for cancer. This review describes the repurposing of these drugs for cancer treatment.

Percutaneous doxycycline treatment of aneurysmal bone cysts with low recurrence rate: a preliminary report

BACKGROUND

Aneurysmal bone cyst (ABC) has a recurrence rate of between 12% and 71% without en bloc resection or amputation. There is no percutaneous ABC treatment drug regimen demonstrating consistent evidence of bone healing with recurrence of < 12%. Doxycycline has properties that may make it appropriate for percutaneous treatment.

QUESTIONS/PURPOSES

We therefore asked: (1) Is there reduction in ABC lytic cyst volume with injectable doxycycline? (2) Is it associated with thickening of involved bony cortex? (3) Is the recurrence rate after percutaneous treatment < 12%?

METHODS

We retrospectively reviewed 20 patients who underwent percutaneous treatment of ABCs with doxycycline from 2006 to 2010. The mean age was 10 years (range, 3-18 years). There were 21 treatment locations: humerus (six), spine (five), clavicle (two), fibula (one), femur (two), ulna (two), tibia (two), and scapula (one). Twenty patients completed treatment involving 118 treatment sessions (two to 14 sessions per patient). Treatment response was evaluated radiographically by measuring the lytic component and thickness of involved cortex. Recurrence was indicated by new areas of lytic destruction after completion of treatment. The minimum followup was 24 months (mean, 38 months).

RESULTS

Twenty of 20 patients demonstrated reduction in lytic destruction and bony healing. All patients demonstrated cortical thickening. One patient demonstrated recurrent minimal lytic destruction after 20 months of observation.

CONCLUSIONS

In this series, patients undergoing percutaneous doxycycline treatment of ABCs demonstrated a healing response and a recurrence rate of 5% at more than 24 months.

Matrix metalloproteinase inhibitor COL-3 prevents the development of paclitaxel-induced hyperalgesia in mice

OBJECTIVE

To study the potential of chemically modified tetracycline-3 (COL-3), a potent matrix metalloproteinase (MMP) inhibitor, to protect against the development of paclitaxel-induced painful neuropathy and its immunomodulatory effects.

MATERIALS AND METHODS

The reaction latency to thermal stimuli (hot plate test) of female BALB/c mice was recorded before and after treatment with paclitaxel (2 mg/kg i.p.), paclitaxel plus COL-3 (4, 20 or 40 mg/kg p.o.) or their vehicles for 5 consecutive days. Gene transcripts of CD11b (marker for microglia), 5 cytokines (IFN-γ, IL-1β, IL-6, IL-10 and TNF-α) and 3 chemokines (CCL2, CXCL10 and CX3CL1) were quantified by real-time PCR in the brains, spinal cords and spleens of mice sacrificed on day 7 after treatment.

RESULTS

Treatment with paclitaxel reduced the reaction latency time to thermal stimuli (thermal hyperalgesia) for 4 weeks, with maximum effect on days 7 and 10. The coadministration of paclitaxel with COL-3 40 mg/kg, but not lower doses, prevented the development of paclitaxel-induced thermal hyperalgesia. Treatment with paclitaxel alone or coadministration with COL-3 increased CD11b transcript levels in the brain but not in the spinal cord. Treatment with paclitaxel reduced IL-6 transcript levels in the spinal cord but did not alter the transcript levels of other cytokines or chemokines in the brain, spinal cord or spleen. The coadministration of COL-3 with paclitaxel significantly increased the transcript levels of IL-6 in the spleen and decreased CX3CL1 transcripts in the brain in comparison to treatment with paclitaxel alone.

CONCLUSION

Our results indicate that the MMP inhibitor COL-3 protected against paclitaxel-induced thermal hyperalgesia and, thus, could be useful in the prevention of chemotherapy-induced painful neuropathy.

Chemically modified tetracyclines: Novel therapeutic agents in the management of chronic periodontitis

Chronic periodontitis is a complex infection initiated by gram-negative bacteria which destroy the supporting structures of the tooth. Recently, it has been recognized that it is the host response to bacterial infection which causes greater destruction of the connective tissue elements, periodontal ligament and alveolar bone in periodontitis. This has led to the development of various host modulating approaches to target cells and their destructive mediators involved in tissue degradation. Chemically modified tetracyclines (CMTs) are derivatives of tetracycline group of drugs which lack antimicrobial action but have potent host modulating affects. They inhibit pathologically elevated matrix metal loproteinases, pro-inflammtory cytokines and other destructive mediators. Bone resorption is also suppressed due to their combined anti-proteinase and apoptotic affects on osteoblasts and osteoclasts, respectively. Development of resistant bacteria and gastrointestinal toxicity seen with parent tetracyclines is not produced by CMTs. Hence, CMTs are viewed as potential therapeutic agents in the management of chronic diseases like periodontitis that involve destruction of connective tissue and bone.