The Lysyl Oxidase G473A Polymorphism Exacerbates Oral Cancer Development in Humans and Mice.

Oral cancer is primarily squamous-cell carcinoma with a 5-year survival rate of approximately 50%. Lysyl oxidase (LOX) participates in collagen and elastin maturation. The propeptide of LOX is released as an 18 kDa protein (LOX-PP) in the extracellular environment by procollagen C-proteinases and has tumor-inhibitory properties. A polymorphism in the propeptide region of LOX (rs1800449, G473A) results in a single amino acid substitution of Gln for Arg. Here we investigated the frequency of rs1800449 in OSCC employing TCGA database resources and determined the kinetics and severity of precancerous oral lesion development in wildtype and corresponding knockin mice after exposure to 4-nitroquinoline oxide (4 NQO) in drinking water. Data show that the OSCC is more common in humans carrying the variant compared to the wildtype. Knockin mice are more susceptible to lesion development. The immunohistochemistry of LOX in mouse tissues and in vitro studies point to a negative feedback pathway of wildtype LOX-PP on LOX expression that is deficient in knockin mice. Data further demonstrate modulations of T cell phenotype in knockin mice toward a more tumor-permissive condition. Data provide initial evidence for rs1800449 as an oral cancer susceptibility biomarker and point to opportunities to better understand the functional mechanism of LOX-PP cancer inhibitory activity.

Therapeutic Targeting Notch2 Protects Bone Micro-Vasculatures from Methotrexate Chemotherapy-Induced Adverse Effects in Rats.

Intensive cancer chemotherapy is well known to cause bone vasculature disfunction and damage, but the mechanism is poorly understood and there is a lack of treatment. Using a rat model of methotrexate (MTX) chemotherapy (five once-daily dosses at 0.75 mg/kg), this study investigated the roles of the Notch2 signalling pathway in MTX chemotherapy-induced bone micro-vasculature impairment. Gene expression, histological and micro-computed tomography (micro-CT) analyses revealed that MTX-induced micro-vasculature dilation and regression is associated with the induction of Notch2 activity in endothelial cells and increased production of inflammatory cytokine tumour necrosis factor alpha (TNFα) from osteoblasts (bone forming cells) and bone marrow cells. Blockade of Notch2 by a neutralising antibody ameliorated MTX adverse effects on bone micro-vasculature, both directly by supressing Notch2 signalling in endothelial cells and indirectly via reducing TNFα production. Furthermore, in vitro studies using rat bone marrow-derived endothelial cell revealed that MTX treatment induces Notch2/Hey1 pathway and negatively affects their ability in migration and tube formation, and Notch2 blockade can partially protect endothelial cell functions from MTX damage.

Functions and Mechanisms of Pro-Lysyl Oxidase Processing in Cancers and Eye Pathologies with a Focus on Diabetic Retinopathy.

Lysyl oxidases are multifunctional proteins derived from five lysyl oxidase paralogues (LOX) and lysyl oxidase-like 1 through lysyl oxidase-like 4 (LOXL1-LOXL4). All participate in the biosynthesis of and maturation of connective tissues by catalyzing the oxidative deamination of lysine residues in collagens and elastin, which ultimately results in the development of cross-links required to function. In addition, the five LOX genes have been linked to fibrosis and cancer when overexpressed, while tumor suppression by the propeptide derived from pro-LOX has been documented. Similarly, in diabetic retinopathy, LOX overexpression, activity, and elevated LOX propeptide have been documented. The proteolytic processing of pro-forms of the respective proteins is beginning to draw attention as the resultant peptides appear to exhibit their own biological activities. In this review we focus on the LOX paralogue, and what is known regarding its extracellular biosynthetic processing and the still incomplete knowledge regarding the activities and mechanisms of the released lysyl oxidase propeptide (LOX-PP). In addition, a summary of the roles of both LOX and LOX-PP in diabetic retinopathy, and brief mentions of the roles for LOX and closely related LOXL1 in glaucoma, and keratoconus, respectively, are included.

Notch2 Blockade Mitigates Methotrexate Chemotherapy-Induced Bone Loss and Marrow Adiposity.

Childhood cancer methotrexate (MTX) chemotherapy often causes bone growth impairments, bone loss, and increased risks of fractures during or after treatment, for which the pathobiology is unclear and there is a lack of specific treatment. Our time course analyses of long bones from rats receiving intensive MTX treatment (mimicking a clinical protocol) found decreased trabecular bone volume, increased osteoclast formation and activity, increased adipogenesis in the expense of osteogenesis from the bone marrow stromal cells at days 6 and 9 following the first of five daily MTX doses. For exploring potential mechanisms, PCR array expression of 91 key factors regulating bone homeostasis was screened with the bone samples, which revealed MTX treatment-induced upregulation of Notch receptor NOTCH2, activation of which is known to be critical in skeletal development and bone homeostasis. Consistently, increased Notch2 activation in bones of MTX-treated rats was confirmed, accompanied by increased expression of Notch2 intracellular domain protein and Notch target genes HEY1, HES1 and HEYL. To confirm the roles of Notch2 signalling, a neutralising anti-Notch2 antibody or a control IgG was administered to rats during MTX treatment. Microcomputed tomography analyses demonstrated that trabecular bone volume was preserved by MTX+anti-Notch2 antibody treatment. Anti-Notch2 antibody treatment ameliorated MTX treatment-induced increases in osteoclast density and NFATc1 and RANKL expression, and attenuated MTX-induced bone marrow adiposity via regulating Wnt/ß-catenin signalling and PPARγ expression. Thus, Notch2 signalling plays an important role in mediating MTX treatment-induced bone loss and bone marrow adiposity, and targeting Notch2 could be a potential therapeutic option.

Methotrexate treatment suppresses osteoblastic differentiation by inducing Notch2 signaling and blockade of Notch2 rescues osteogenesis by preserving Wnt/ß-catenin signaling.

Methotrexate (MTX) is a commonly used antimetabolite in cancer treatment. Its intensive use is linked with skeletal adverse effects such as reduced bone formation and bone loss, and yet little information is available on molecular mechanisms underlying MTX-induced impaired bone formation. This study investigated the effects of MTX treatment at a clinical chemotherapy relevant dose on osteogenic differentiation in MC3T3E1 osteoblastic cells. To investigate the potential mechanisms, the expression of 87 genes regulating osteoblast differentiation and bone homeostasis was screened in MTX-treated versus untreated cells by polymerase chain reaction (PCR) arrays and results illustrated significant upregulation of Notch2 and Notch target genes at both early and late stages of MC3T3E1 differentiation following MTX treatment. To confirm the roles of Notch2 pathway and its potential action mechanisms, MC3T3E1 cells were treated with MTX with an anti-Notch2 neutralizing antibody or control IgG and effects were examined on osteogenesis and activation of the Wnt/ß-catenin pathway. Our results demonstrated that induction of Notch2 activity is associated with MTX adverse effects on osteogenic differentiation and blocking Notch2 rescues osteoblast differentiation by preserving activation of the Wnt/ß-catenin pathway.

Roles of MicroRNAs in Osteogenesis or Adipogenesis Differentiation of Bone Marrow Stromal Progenitor Cells.

Bone marrow stromal cells (BMSCs) are multipotent cells which can differentiate into chondrocytes, osteoblasts, and fat cells. Under pathological stress, reduced bone formation in favour of fat formation in the bone marrow has been observed through a switch in the differentiation of BMSCs. The bone/fat switch causes bone growth defects and disordered bone metabolism in bone marrow, for which the mechanisms remain unclear, and treatments are lacking. Studies suggest that small non-coding RNAs (microRNAs) could participate in regulating BMSC differentiation by disrupting the post-transcription of target genes, leading to bone/fat formation changes. This review presents an emerging concept of microRNA regulation in the bone/fat formation switch in bone marrow, the evidence for which is assembled mainly from in vivo and in vitro human or animal models. Characterization of changes to microRNAs reveals novel networks that mediate signalling and factors in regulating bone/fat switch and homeostasis. Recent advances in our understanding of microRNAs in their control in BMSC differentiation have provided valuable insights into underlying mechanisms and may have significant potential in development of new therapeutics.

Roles of apoptotic chondrocyte-derived CXCL12 in the enhanced chondroclast recruitment following methotrexate and/or dexamethasone treatment.

Intensive use of methotrexate (MTX) and/or dexamethasone (DEX) for treating childhood malignancies is known to cause chondrocyte apoptosis and growth plate dysfunction leading to bone growth impairments. However, mechanisms remain vague and it is unclear whether MTX and DEX combination treatment could have additive effects in the growth plate defects. In this study, significant cell apoptosis was induced in mature ATDC5 chondrocytes after treatment for 48 h with 10-5 M MTX and/or 10-6 M DEX treatment. PCR array assays with treated cells plus messenger RNA and protein expression confirmation analyses identified chemokine CXCL12 having the most prominent induction in each treatment group. Conditioned medium from treated chondrocytes stimulated migration of RAW264.7 osteoclast precursor cells and formation of osteoclasts, and these stimulating effects were inhibited by the neutralizing antibody for CXCL12. Additionally, while MTX and DEX combination treatment showed some additive effects on apoptosis induction, it did not have additive or counteractive effects on CXCL12 expression and its functions in enhancing osteoclastic recruitment and formation. In young rats treated acutely with MTX, there was increased expression of CXCL12 in the tibial growth plate, and more resorbing chondroclasts were found present at the border between the hypertrophic growth plate and metaphysis bone. Thus, the present study showed an association between induced chondrocyte apoptosis and stimulated osteoclastic migration and formation following MTX and/or DEX treatment, which could be potentially or at least partially linked molecularly by CXCL12 induction. This finding may contribute to an enhanced mechanistic understanding of bone growth impairments following MTX and/or DEX therapy.

ß-Catenin signaling is important for osteogenesis and hematopoiesis recovery following methotrexate chemotherapy in rats.

Cancer chemotherapy can significantly impair the bone formation and cause myelosuppression; however, their recovery potentials and mechanisms remain unclear. This study investigated the roles of the ß-catenin signaling pathway in bone and bone marrow recovery potentials in rats treated with antimetabolite methotrexate (MTX) (five once-daily injections, 0.75 mg/kg) with/without ß-catenin inhibitor indocyanine green (ICG)-001 (oral, 200 mg/kg/day). ICG alone reduced trabecular bone volume and bone marrow cellularity. In MTX-treated rats, ICG suppressed bone volume recovery on Day 11 after the first MTX injection. ICG exacerbated MTX-induced decreases on Day 9 osteoblast numbers on bone surfaces, their formation in vitro from bone marrow stromal cells (osteogenic differentiation/mineralization), as well as expression of osteogenesis-related markers Runx2, Osx, and OCN in bone, and it suppressed their subsequent recoveries on Day 11. On the other hand, ICG did not affect MTX-induced increased osteoclast density and the level of the osteoclastogenic signal (RANKL/OPG expression ratio) in bone, suggesting that ICG inhibition of ß-catenin does nothing to abate the increased bone resorption induced by MTX. ICG also attenuated bone marrow cellularity recovery on Day 11, which was associated with the suppressed recovery of CD34+ or c-Kit+  hematopoietic progenitor cell contents. Thus, ß-catenin signaling is important for osteogenesis and hematopoiesis recoveries following MTX chemotherapy.

Opioids and matrix metalloproteinases: the influence of morphine on MMP-9 production and cancer progression.

Opioids are widely administered to alleviate pain, including chronic pain in advanced cancer patients. Among opioids, morphine is one of the most clinically effective drugs for the palliative management of severe pain. In the last few decades, there has been a debate around the possible influence of opioids such as morphine on tumour growth and metastasis. Whilst several in vitro and in vivo studies suggest the possible modulatory effects of morphine on tumour cells, little is known about the impact of this analgesic drug on other mediators such as matrix metalloproteinases (MMPs) that play a key role in the control of cancer cell invasion and metastasis. MMP-9 has been considered as one of the principal mediators in regulation of not only the initial steps of cancer but during the invasion and spreading of cancer cells to distant organs. Herein, current studies regarding the direct and indirect effects of morphine on regulation of MMP-9 production are discussed. In addition, drawing from previous in vivo and in vitro studies on morphine action in regulating MMP-9 production, the potential roles of several underlying factors are summarised, including nuclear factor kappa-B and intracellular molecules such as nitric oxide.

Critical limb ischemia: Current and novel therapeutic strategies.

Critical limb ischemia (CLI) is the advanced stage of peripheral artery disease spectrum and is defined by limb pain or impending limb loss because of compromised blood flow to the affected extremity. Current conventional therapies for CLI include amputation, bypass surgery, endovascular therapy, and pharmacological approaches. Although these conventional therapeutic strategies still remain as the mainstay of treatments for CLI, novel and promising therapeutic approaches such as proangiogenic gene/protein therapies and stem cell-based therapies have emerged to overcome, at least partially, the limitations and disadvantages of current conventional therapeutic approaches. Such novel CLI treatment options may become even more effective when other complementary approaches such as utilizing proper bioscaffolds are used to increase the survival and engraftment of delivered genes and stem cells. Therefore, herein, we address the benefits and disadvantages of current therapeutic strategies for CLI treatment and summarize the novel and promising therapeutic approaches for CLI treatment. Our analyses also suggest that these novel CLI therapeutic strategies show considerable advantages to be used when current conventional methods have failed for CLI treatment.

Adipose-derived stem cells for wound healing.

Wound healing is a complex but a fine-tuned biological process in which human skin has the ability to regenerate itself following damage. However, in particular conditions such as deep burn or diabetes the process of wound healing is compromised. Despite investigations on the potency of a wide variety of stem cells for wound healing, adipose-derived stem cells (ASCs) seem to possess the least limitations for clinical applications, and literature showed that ASCs can improve the process of wound healing very likely by promoting angiogenesis and/or vascularisation, modulating immune response, and inducing epithelialization in the wound. In the present review, advantages and disadvantages of various stem cells which can be used for promoting wound healing are discussed. In addition, potential mechanisms of action by which ASCs may accelerate wound healing are summarised. Finally, clinical studies applying ASCs for wound healing and the associated limitations are reviewed.

Osteoblast derived-neurotrophin­3 induces cartilage removal proteases and osteoclast-mediated function at injured growth plate in rats.

Faulty bony repair causes dysrepair of injured growth plate cartilage and bone growth defects in children; however, the underlying mechanisms are unclear. Recently, we observed the prominent induction of neurotrophin­3 (NT-3) and its important roles as an osteogenic and angiogenic factor promoting the bony repair. The current study investigated its roles in regulating injury site remodelling. In a rat tibial growth plate drill-hole injury repair model, NT-3 was expressed prominently in osteoblasts at the injury site. Recombinant NT-3 (rhNT-3) systemic treatment enhanced, but NT-3 immunoneutralization attenuated, expression of cartilage-removal proteases (MMP-9 and MMP-13), presence of bone-resorbing osteoclasts and expression of osteoclast protease cathepsin K, and remodelling at the injury site. NT-3 was also highly induced in cultured mineralizing rat bone marrow stromal cells, and the conditioned medium augmented osteoclast formation and resorptive activity, an ability that was blocked by presence of anti-NT-3 antibody. Moreover, NT-3 and receptor TrkC were induced during osteoclastogenesis, and rhNT-3 treatment activated TrkC downstream kinase Erk1/2 in differentiating osteoclasts although rhNT-3 alone did not affect activation of osteoclastogenic transcription factors NF-κB or NFAT in RAW264.7 osteoclast precursor cells. Furthermore, rhNT-3 treatment increased, but NT-3 neutralization reduced, expression of osteoclastogenic cytokines (RANKL, TNF-α, and IL-1) in mineralizing osteoblasts and in growth plate injury site, and rhNT-3 augmented the induction of these cytokines caused by RANKL treatment in RAW264.7 cells. Thus, injury site osteoblast-derived NT-3 is important in promoting growth plate injury site remodelling, as it induces cartilage proteases for cartilage removal and augments osteoclastogenesis and resorption both directly (involving activing Erk1/2 and substantiating RANKL-induced increased expression of osteoclastogenic signals in differentiating osteoclasts) and indirectly (inducing osteoclastogenic signals in osteoblasts).