Genetic network and pathway analysis of differentially expressed proteins during critical cellular events in fracture repair

Development of methods for detecting the fate of mesenchymal stem cells regulated by bone bioactive materials

The fate of mesenchymal stem cells (MSCs) is regulated by biological, physical and chemical signals. Developments in biotechnology and materials science promoted the occurrence of bioactive materials which can provide physical and chemical signals for MSCs to regulate their fate. In order to design and synthesize materials that can precisely regulate the fate of MSCs, the relationship between the properties of materials and the fate of mesenchymal stem cells need to be clarified, in which the detection of the fate of mesenchymal stem cells plays an important role. In the past 30 years, a series of detection technologies have been developed to detect the fate of MSCs regulated by bioactive materials, among which high-throughput technology has shown great advantages due to its ability to detect large amounts of data at one time. In this review, the latest research progresses of detecting the fate of MSCs regulated by bone bioactive materials (BBMs) are systematically reviewed from traditional technology to high-throughput technology which is emphasized especially. Moreover, current problems and the future development direction of detection technologies of the MSCs fate regulated by BBMs are prospected. The aim of this review is to provide a detection technical framework for researchers to establish the relationship between the properties of BMMs and the fate of MSCs, so as to help researchers to design and synthesize BBMs better which can precisely regulate the fate of MSCs.

Characterization of an umbilical cord blood sourced product suitable for allogeneic applications

Aim: Umbilical cord blood (UCB) sourced allografts are promising interventions for tissue regeneration. As applications of these allografts and regulations governing them continue to evolve, we were prompted to identify parameters determining their quality, safety and regenerative potential. Materials & methods: Flow-cytometry, mass-spectrometry, protein multiplexing, nanoparticle tracking analysis and standard biological techniques were employed. Results: Quality attributes of a uniquely processed UCB-allograft (UCBr) were enumerated based on identity (cell viability, immunophenotyping, proteomic profiling, and quantification of relevant cytokines); safety (bioburden and microbiological screening), purity (endotoxin levels) and potency (effect of UCBr on chondrocytes and mesenchymal stem cells derived exosomes). These attributes were stable up to 24 months in cryopreserved UCBr. Conclusion: We identified a comprehensive panel of tests to establish the clinical efficacy and quality control attributes of a UCB-sourced allograft.

Identification of key gene networks associated with fracture healing using αSMA‑labeled progenitor cells

The aim of the present study was to investigate the key gene network in fracture healing. The dataset GSE45156 was downloaded from the Gene Expression Omnibus. Differentially expressed genes (DEGs) were identified using the linear models for microarray data package of Bioconductor. Subsequently, Gene Ontology (GO) functional and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were conducted for DEGs in day 2 and 6 fractured samples via the Database for Annotation, Visualization and Integrated Discovery. Furthermore, protein-protein interactions (PPIs) of DEGs were analyzed and a PPI network was constructed. A total of 774 and 1,172 DEGs were identified in day 2 and 6 fractured samples, respectively, compared with unfractured controls. Of the DEGs in day 2 and 6 fractured samples, various upregulated DEGs, including protein kinase C α (Prkca) and B-cell lymphoma antagonist/killer 1 were significantly enriched in GO terms associated with cell death, and certain downregulated DEGs, including fms-related tyrosine kinase 1 (Flt1), nitric oxide synthase 3 (Nos3), bone morphogenetic protein 4 (Bmp4) and Notch1 were enriched in GO terms associated with angiogenesis. Furthermore, a series of downregulated DEGs were enriched in the Notch signaling pathway, including hes family bHLH transcription factor 1 and Notch1. Certain DEGs had a high degree and interacted with each other, including Flt1, Nos3, Bmp4 and Notch1, and Prkca and ras-related C3 botulinum toxin substrate 3. The up and downregulated DEGs may exert critical functions by interactively regulating angiogenesis or apoptosis.

Identification of potential target genes and related regulatory transcription factors in spontaneous hairline fracture induced by hypervitaminosis A

BACKGROUND

The aim was to research the molecular changes of bone cells induced by excessive dose of vitamin A, and analyze molecular mechanism underlying spontaneous fracture.

METHODS

The gene expression profile of GSE29859, including 4 cortical bone marrow samples with excessive doses of Vitamin A and 4 control cortical bone marrow samples, was obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DGEs) between cortical bone marrow samples and control samples were screened out and pathway enrichment analysis was undertaken. Based on the MSigDB database, the potential regulatory transcription factors (TFs) were identified.

RESULTS

A total of 373 DEGs including 342 up- and 31 down-regulated genes were identified. These DEGs were significantly enriched in pathways of protein processing in endoplasmic reticulum, ubiquitin mediated proteolysis and glycerophospholipid metabolism. Finally, the most significant regulatory TFs were obtained, including E2F Transcription Factor 1 (E2F1), GA Binding Protein Transcription Factor (GABP), Nuclear Factor, Erythroid 2-Like 2 (NRF2) and ELK1, Member of ETS Oncogene Family (ELK1).

CONCLUSION

Key TFs including E2F1, GABP, NRF2 and ELK1 and their targets genes such as Ube2d3, Uba1, Phb2 and Tomm22 may play potential key roles in spontaneous fracture induced by hypervitaminosis A. The pathways of protein processing in endoplasmic reticulum, ubiquitin mediated proteolysis and glycerophospholipid metabolism may be key mechanisms involved in spontaneous fracture induced by hypervitaminosis A. Our findings will provide new insights for the target selection in clinical application to prevent spontaneous fracture induced by hypervitaminosis A.

Influence of 5-amino-3-methyl-4-isoxazolecarbohydrazide on selective gene expression in Caco-2 cultured cells

The 5-amino-3-methyl-4-isoxazolecarboxylic acid hydrazide (HIX) is a synthetic isoxazole derivative with a potential for development as an anti-inflammatory drug candidate. The goal of this study was to explore in vitro autoimmune and inflammatory gene modulation by HIX in human Caco-2 cultured cells. The effect of low dose of HIX was tested on the expression level of RNA in 24 h Caco-2 cultures using the QIAGEN Th17 for Autoimmunity & Inflammation RT² Profiler PCR Array. We choose the PCR technology as the most reliable and sensitive gene expression profiling method for analyzing specific gene regulatory networks. In all experiments, Leflunomide (5-methyl-N-[4-(trifluoromethyl)phenyl]-4-isoxazolecarboxamide), an immuno-suppressive disease-modifying antirheumatic drug was used, as a reference to clinical utility of the isoxazole derivatives. Changes in RNA levels were analyzed and differentially expressed genes with at least 2-fold change were identified. For the majority of genes tested, the effects of HIX and Leflunomide were similar, including up-regulation of CX3CL1 and IL-17F, and down-regulation of IL-10 and TLR4. However twelve genes were were differently regulated by the two compounds: interleukins (IL) IL-1B, IL-6 and a chemokine CCL22 were upregulated by HIX and significantly supressed by Leflunomide. In contrary, IL-2 and IL-27 were upregulated by Leflunomide and suppressed by HIX. The network search by Ingenuity Pathway Analysis showed, that majority of differentially expressed genes were involved in cellular inflammatory responses. These results suggest that 5-amino-3-methyl-4-isoxazolecarbohydrazide has a potential for future clinical developments with structure modification as a disease modifying agent in different than Leflunomide applications.

Differential gene expression profiling of functionally and developmentally distinct human prostate epithelial populations

BACKGROUND

Human fetal prostate buds appear in the 10th gestational week as solid cords, which branch and form lumens in response to androgen 1. Previous in vivo analysis of prostate epithelia isolated from benign prostatectomy specimens indicated that Epcam⁺ CD44⁻ CD49f(Hi) basal cells possess efficient tubule initiation capability relative to other subpopulations 2. Stromal interactions and branching morphogenesis displayed by adult tubule-initiating cells (TIC) are reminiscent of fetal prostate development. In the current study, we evaluated in vivo tubule initiation by human fetal prostate cells and determined expression profiles of fetal and adult epithelial subpopulations in an effort to identify pathways used by TIC.

METHODS

Immunostaining and FACS analysis based on Epcam, CD44, and CD49f expression demonstrated the majority (99.9%) of fetal prostate epithelial cells (FC) were Epcam⁺ CD44⁻ with variable levels of CD49f expression. Fetal populations isolated via cell sorting were implanted into immunocompromised mice. Total RNA isolation from Epcam⁺ CD44⁻ CD49f(Hi) FC, adult Epcam⁺ CD44⁻ CD49f(Hi) TIC, Epcam⁺ CD44⁺ CD49f(Hi) basal cells (BC), and Epcam⁺ CD44⁻ CD49f(Lo) luminal cells (LC) was performed, followed by microarray analysis of 19 samples using the Affymetrix Gene Chip Human U133 Plus 2.0 Array. Data was analyzed using Partek Genomics Suite Version 6.4. Genes selected showed >2-fold difference in expression and P < 5.00E-2. Results were validated with RT-PCR.

RESULTS

Grafts retrieved from Epcam⁺ CD44⁻ fetal cell implants displayed tubule formation with differentiation into basal and luminal compartments, while only stromal outgrowths were recovered from Epcam- fetal cell implants. Hierarchical clustering revealed four distinct groups determined by antigenic profile (TIC, BC, LC) and developmental stage (FC). TIC and BC displayed basal gene expression profiles, while LC expressed secretory genes. FC had a unique profile with the most similarities to adult TIC. Functional, network, and canonical pathway identification using Ingenuity Pathway Analysis Version 7.6 compiled genes with the highest differential expression (TIC relative to BC or LC). Many of these genes were found to be significantly associated with prostate tumorigenesis.

CONCLUSIONS

Our results demonstrate clustering gene expression profiles of FC and adult TIC. Pathways associated with TIC are known to be deregulated in cancer, suggesting a cell-of-origin role for TIC versus re-emergence of pathways common to these cells in tumorigenesis.

Osteogenic properties of PBLG-g-HA/PLLA nanocomposites

New development of biomaterial scaffolds remains a prominent issue for the regeneration of lost or fractured bone. Of these scaffolds, a number of bioactive polymers have been synthesized and fabricated for diverse biological roles. Although recent evidence has demonstrated that composite scaffolds such as HA/PLLA have improved properties when compared to either HA or PLLA alone, recent investigations have demonstrated that the phase compatibility between HA and PLLA layers is weak preventing optimal enhancement of the mechanical properties and making the composites prone to breakdown. In the present study, poly (γ-benzyl-L-glutamate) modified hydroxyapatite/(poly (L-lactic acid)) (PBLG-g-HA/PLLA) composite scaffolds were fabricated with improved phase compatibility and tested for their osteogenic properties in 18 Wistar female rats by analyzing new bone formation in 3 mm bilateral femur defects in vivo. At time points, 2, 4 and 8 weeks post surgery, bone formation was evaluated by µ-CT and histological analysis by comparing 4 treatment groups; 1) blank defect, 2) PLLA, 3) HA/PLLA and 4) PBLG-g-HA/PLLA scaffolds. The in vivo analysis demonstrated that new bone formation was much more prominent in HA/PLLA and PBLG-g-HA/PLLA groups as depicted by µ-CT, H&E staining and immunohistochemistry for collagen I. TRAP staining was also utilized to determine the influence of osteoclast cell number and staining intensity to the various scaffolds. No significant differences in either staining intensity or osteoclast numbers between all treatment modalities was observed, however blank defects did contain a higher number of osteoclast-like cells. The results from the present study illustrate the potential of PBLG-g-HA/PLLA scaffolds for bone tissue engineering applications by demonstrating favorable osteogenic properties.

Constitutive activation of IKK2/NF-κB impairs osteogenesis and skeletal development

Pathologic conditions impair bone homeostasis. The transcription factor NF-κB regulates bone homeostasis and is central to bone pathologies. Whereas contribution of NF-κB to heightened osteoclast activity is well-documented, the mechanisms underlying NF-κB impact on chondrocytes and osteoblasts are scarce. In this study, we examined the effect of constitutively active IKK2 (IKK2ca) on chondrogenic and osteogenic differentiation. We show that retroviral IKK2ca but not GFP, IKK2WT, or the inactive IKK2 forms IKK2KM and IKK2SSAA, strongly suppressed osteogenesis and chondrogenesis, in vitro. In order to explore the effect of constitutive NF-κB activation on bone formation in vivo, we activated this pathway in a conditional fashion. Specifically, we crossed the R26StopIKK2ca mice with mice carrying the Col2-cre in order to express IKK2ca in osteoblasts and chondrocytes. Both chondrocytes and osteoblasts derived from Col2Cre/IKK2ca expressed IKK2ca. Mice were born alive yet died shortly thereafter. Histologically, newborn Col2Cre+/RosaIKK2ca heterozygotes (Cre+IKK2ca_w/f (het)) and homozygotes (Cre+IKK2ca_f/f (KI)) showed smaller skeleton, deformed vertebrate and reduced or missing digit ossification. The width of neural arches, as well as ossification in vertebral bodies of Cre+IKK2ca_w/f and Cre+IKK2ca_f/f, was reduced or diminished. H&E staining of proximal tibia from new born pups revealed that Cre+IKK2ca_f/f displayed disorganized hypertrophic zones within the smaller epiphysis. Micro-CT analysis indicated that 4-wk old Cre+IKK2ca_w/f has abnormal trabecular bone in proximal tibia compared to WT littermates. Mechanistically, ex-vivo experiments showed that expression of differentiation markers in calvarial osteoblasts derived from newborn IKK2ca knock-in mice was diminished compared to WT-derived cells. In situ hybridization studies demonstrated that the hypertrophic chondrocyte marker type-X collagen, the pre-hypertrophic chondrocyte markers Indian hedgehog and alkaline phosphatase, and the early markers Aggrecan and type-II collagen were reduced in Cre+IKK2ca_w/f and Cre+IKK2ca_f/f mice. Altogether, the in-vitro, in vivo and ex-vivo evidence suggest that IKK2ca perturbs osteoblast and chondrocyte maturation and impairs skeletal development.

Cyclic tensile strain enhances osteogenesis and angiogenesis in mesenchymal stem cells from osteoporotic donors

We have shown that the uniaxial cyclic tensile strain of magnitude 10% promotes and enhances osteogenesis of human mesenchymal stem cells (hMSC) and human adipose-derived stem cells (hASC) from normal, nonosteoporotic donors. In the present study, MSC from osteoporotic donors were analyzed for changes in mRNA expression in response to 10% uniaxial tensile strain to identify potential mechanisms underlying the use of this mechanical loading paradigm for prevention and treatment of osteoporosis. Human MSC isolated from three female, postmenopausal osteoporotic donors were analyzed for their responses to mechanical loading using microarray analysis of over 47,000 gene probes. Human MSC were seeded in three-dimensional collagen type I constructs to mimic the organic extracellular matrix of bone and 10% uniaxial cyclic tensile strain was applied to promote osteogenesis. Seventy-nine genes were shown to be regulated within hMSC from osteoporotic donors in response to 10% cyclic tensile strain. Upregulation of six genes were further confirmed with real-time RT-PCR: jun D proto-oncogene (JUND) and plasminogen activator, urokinase receptor (PLAUR), two genes identified as potential key molecules from network analysis; phosphoinositide-3-kinase, catalytic, delta polypeptide (PIK3CD) and wingless-type MMTV integration site family, member 5B (WNT5B), two genes with known importance in bone biology; and, PDZ and LIM domain 4 (PDLIM4) and vascular endothelial growth factor A (VEGFA), two genes that we have previously shown are significantly regulated in hASC in response to this mechanical stimulus. Function analysis indicated that 10% cyclic tensile strain induced expression of genes associated with cell movement, cell proliferation, and tissue development, including development in musculoskeletal and cardiovascular systems. Our results demonstrate that hMSC from aged, osteoporotic donors are capable of enhanced osteogenic differentiation in response to 10% cyclic tensile strain with significant increases in the expression of genes associated with enhanced cell proliferation, musculoskeletal development, and angiogenesis. Surprisingly, cyclic tensile strain of magnitude 10% not only enhanced osteogenesis in hMSC from osteoporotic donors, but also enhanced expression of angiogenic factors. Better understanding and methodologies to promote osteogenesis in hMSC from elderly, osteoporotic donors may greatly facilitate achieving long-term success in bone regeneration and functional bone tissue engineering for this ever-growing patient population.

Microarray expression analysis of genes and pathways involved in growth plate cartilage injury responses and bony repair

The injured growth plate cartilage is often repaired by a bone bridge which causes bone growth deformities. Whilst previous studies have identified sequential inflammatory, fibrogenic, osteogenic and bone remodelling responses involved in the repair process, the molecular pathways which regulated these cellular events remain unknown. In a rat growth plate injury model, tissue from the injury site was collected across the time-course of bone bridge formation using laser capture microdissection and was subjected to Affymetrix microarray gene expression analysis. Real Time PCR and immunohistochemical analyses were used to confirm changes in levels of expression of some genes identified in microarray. Four major functional groupings of differentially expressed genes with known roles in skeletal development were identified across the time-course of bone bridge formation, including Wnt signalling (SFRP1, SFRP4, β-catenin, Csnk2a1, Tcf7, Lef1, Fzd1, Fzd2, Wisp1 and Cpz), BMP signalling (BMP-2, BMP-6, BMP-7, Chrd, Chrdl2 and Id1), osteoblast differentiation (BMP-2, BMP-6, Chrd, Hgn, Spp1, Axin2, β-catenin, Bglap2) and skeletal development (Chrd, Mmp9, BMP-1, BMP-6, Spp1, Fgfr1 and Traf6). These studies provide insight into the molecular pathways which act cooperatively to regulate bone formation following growth plate cartilage injury and highlight potential therapeutic targets to limit bone bridge formation.

Bone regeneration and stem cells

This invited review covers research areas of central importance for orthopaedic and maxillofacial bone tissue repair, including normal fracture healing and healing problems, biomaterial scaffolds for tissue engineering, mesenchymal and foetal stem cells, effects of sex steroids on mesenchymal stem cells, use of platelet-rich plasma for tissue repair, osteogenesis and its molecular markers. A variety of cells in addition to stem cells, as well as advances in materials science to meet specific requirements for bone and soft tissue regeneration by addition of bioactive molecules, are discussed.

Microarray-based gene expression analysis of human osteoblasts in response to different biomaterials

Several biomaterials have been widely used in bone regeneration/substitution procedures in orthopedic and oral surgery. However, how these biomaterials alter osteoblast gene expression is poorly understood. We therefore attempted to address this question by using cDNA microarray technique to identify genes that are differentially regulated in osteoblasts exposed to biomaterials comprehending the biocompatibility spectrum of bioactive (bioglass and hydroxyapatite), bioinert (Ti and stainless steel), and biotolerant (polymethylmethacrylate). By using a cDNA microarray containing 687 human IMAGE sequences, we identified in primary cultures of osteoblastic cells differentiated from the human bone marrow and exposed to these biomaterials, genes whose expression was significantly upregulated or downregulated. Among the differentially expressed genes we have found those involved with cell cycle regulation, cell differentiation and proliferation, apoptosis, cell adhesion, bone mineralization and skeletal development. These results can be relevant to a better understanding of the molecular mechanism underlying the behavior of osteoblasts in bone regenerative procedures.

Effects of Colostrinin on gene expression-transcriptomal network analysis

Colostrinin (CLN) is a uniform mixture of low-molecular weight proline-rich polypeptides isolated from the mother's first milk, colostrum. Exposure of cells to CLN decreases intracellular levels of reactive oxygen species by regulating glutathione metabolism and modulating activities of antioxidant enzymes and mitochondrial function. It also inhibits beta amyloid-induced apoptosis and induces neurite outgrowth of pheochromocytoma cells. Administration of CLN to Alzheimer's disease patients has resulted in a stabilizing effect on cognitive function. We analyzed CLN-induced gene expression changes using high-density oligonucleotide arrays and transcriptomal network analysis. We found that CLN elicited highly complex and multiphasic changes in the gene expression profile of treated cells. CLN treatment affected a total of 58 molecular networks, 27 of which contained at least 10 differentially expressed genes. Here we present CLN-modulated gene networks as potential underlying molecular mechanisms leading to the reported effects of CLN on cellular oxidative state, chemokine and cytokine production, and cell differentiation, as well as on pathological processes like allergy, asthma, Alzheimer's, and other neurological diseases. Based on our results, we also predict possible modulatory effects of CLN on adipocytokine gene networks that play a crucial role in the pathobiology of diabetes, cardiovascular disorders, obesity, and inflammation. Taken together, CLN-altered gene expression networks presented here provide the molecular basis for previously described biological phenomena and predict potential fields of application for CLN in the prevention and treatment of diseases.

Percolation theory relates corticocancellous architecture to mechanical function in vertebrae of inbred mouse strains

Complex corticocancellous skeletal sites such as the vertebra or proximal femur are connected networks of bone capable of transferring mechanical loads. Characterizing these structures as networks may allow us to quantify the load transferring behavior of the emergent system as a function of the connected cortical and trabecular components. By defining the relationship between certain physical bone traits and mechanical load transfer pathways, a clearer picture of the genetic determinants of skeletal fragility can be developed. We tested the hypothesis that the measures provided by network percolation theory will reveal that different combinations of cortical, trabecular, and compositional traits lead to significantly different load transfer pathways within the vertebral bodies among inbred mouse strains. Gross morphologic, micro-architectural, and compositional traits of L5 vertebrae from 15 week old A/J (A), C57BL6/J (B6), and C3H/HeJ (C3H) inbred mice (n=10/strain) were determined using micro-computed tomography. Measures included total cross-sectional area, bone volume fraction, trabecular number, thickness, spacing, cortical area, and tissue mineral density. Two-dimensional coronal sections were converted to network graphs with the cortical shell considered as one highly connected node. Percolation parameters including correlation length (average number of connected nodes between superior and inferior surfaces), chemical length (minimum number of connected nodes between surfaces), and backbone mass (strut number) were measured. Analysis of the topology of the connected bone networks showed that A and B6 mice transfer load through trabecular pathways in the middle of the vertebral body in addition to the cortical shell. C3H mice transfer load primarily through the highly mineralized cortical shell. Thus, the measures provided by percolation theory provide a quantitative approach to study how different combinations of cortical and trabecular traits lead to mechanically functional structures. The data further emphasize the interdependent nature of these physical bone traits suggesting similar genetic variants may affect both trabecular and cortical bone. Therefore, developing a network approach to study corticocancellous architecture during growth should further our understanding of the biological basis of skeletal fragility and, thus, provide novel engineering approaches to studying the genetic basis of fracture risk.

Molecular genetic studies of gene identification for osteoporosis

This review comprehensively summarizes the most important and representative molecular genetics studies of gene identification for osteoporosis published up to the end of September 2007. It is intended to constitute a sequential update of our previously published reviews covering the available data up to the end of 2004. Evidence from candidate gene-association studies, genome-wide linkage and association studies, as well as functional genomic studies (including gene-expression microarray and proteomics) on osteogenesis and osteoporosis, are reviewed separately. Studies of transgenic and knockout mice models relevant to osteoporosis are summarized. The major results of all studies are tabulated for comparison and ease of reference. Comments are made on the most notable findings and representative studies for their potential influence and implications on our present understanding of genetics of osteoporosis. The format adopted by this review should be ideal for accommodating future new advances and studies.

miR-17-92 cluster accelerates adipocyte differentiation by negatively regulating tumor-suppressor Rb2/p130

Adipogenesis involves cell proliferation and differentiation, both of which have been shown to be regulated by micro (mi)RNA. During mouse preadipocyte 3T3L1 cell differentiation, we found that miR-17-92, a miRNA cluster that promotes cell proliferation in various cancers, was significantly up-regulated at the clonal expansion stage of adipocyte differentiation. Stable transfection of 3T3L1 cells with miR-17-92 resulted in accelerated differentiation and increased triglyceride accumulation after hormonal stimulation. By using a luciferase reporter assay, we demonstrated that miR-17-92 directly targeted the 3' UTR region of Rb2/p130, accounting for subsequently reduced Rb2/p130 mRNA and protein quantities at the stage of clonal expansion. siRNA-mediated knock-down of Rb2/p130 at the same stage of clonal expansion recapitulated the phenotype of overexpression of miR-17-92 in the stably transfected 3T3L1 cells. These data indicate that miR-17-92 promotes adipocyte differentiation by targeting and negatively regulating Rb2/p130.

Annexin XI is associated with cisplatin resistance and related to tumor recurrence in ovarian cancer patients

PURPOSE

Ovarian cancer patients treated with cisplatin-based chemotherapy often develop acquired cisplatin resistance and, consequently, cancer recurrence. The precise nature of chemoresistance remains unclear. In this study, a protein identified to be associated with cisplatin resistance in ovarian cancer cells was investigated in ovarian cancer tissues to address its clinical significance.

EXPERIMENTAL DESIGN

Antibody microarrays were used to identify proteins consistently differentially expressed across three pairs of cisplatin-sensitive and cisplatin-resistant ovarian cancer cell lines. Immunoblotting was used to confirm observed alteration of protein expression. The protein expression was further evaluated by immunohistochemical staining using tissue microarrays containing various human normal and malignant tissues and 164 surgical specimens derived from primary and recurrent ovarian cancer patients who underwent primary debulking surgery followed by standard chemotherapeutic regimen.

RESULTS

Annexin XI was down-regulated in all three cisplatin-resistant cell lines as compared with their parent cells. Annexin XI expression was observed in the majority of human normal organs and decreased in some of the most common human malignancies. The expression level of Annexin XI in first recurrent ovarian cancers was much lower than that in primary ovarian cancers (P = 0.0004). Increased Annexin XI immunoreactivity in ovarian cancers seemed to prolong the disease-free interval of patients (P = 0.03). Annexin XI immunoreactivity inversely correlated with in vitro cisplatin resistance in ovarian cancers (P = 0.01).

CONCLUSION

Decreased expression of Annexin XI is characteristic for cisplatin-resistant cancer cells and may contribute to tumor recurrence. Annexin XI may be a potential marker for chemoresistance and earlier recurrence of ovarian cancer patients.

TP508 accelerates fracture repair by promoting cell growth over cell death

TP508 is a synthetic 23-amino acid peptide representing a receptor-binding domain of human thrombin. We have previously shown that a single injection of TP508 accelerates fracture healing in a rat femoral fracture model. To understand how TP508 acts at the protein level during fracture healing, we compared the translational profiles between saline-control and fractured femur at six time points after TP508 treatment using the second generation of BD Clontechtrade mark Antibody Microarray. Here, we demonstrate that TP508 accelerates fracture healing by modulating expression levels of proteins primarily involved in the functional categories of cell cycle, cellular growth and proliferation, and cell death. The majority of those proteins are physically interrelated and functionally overlapped. The action of those proteins is highlighted by a central theme of promoting cell growth via balance of cell survival over cell death signals. This appears to occur through the stimulation of several bone healing pathways including cell cycle-G1/S checkpoint regulation, apoptosis, JAK/STAT, NF-kappaB, PDGF, PI3K/AKT, PTEN, and ERK/MAPK.