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Biomedical subjects

Quan Kang

Publications and source records attributed to Quan Kang.

11 recordsLinked to original sources
PubMed2006

CCN1/Cyr61 is regulated by the canonical Wnt signal and plays an important role in Wnt3A-induced osteoblast differentiation of mesenchymal stem cells.

Marrow mesenchymal stem cells are pluripotent progenitors that can differentiate into bone, cartilage, muscle, and fat cells. Wnt signaling has been implicated in regulating osteogenic differentiation of mesenchymal stem cells. Here, we analyzed the gene expression profile of mesenchymal stem cells that were stimulated with Wnt3A. Among the 220 genes whose expression was significantly changed by 2.5-fold, we found that three members of the CCN family, CCN1/Cyr61, CCN2/connective tissue growth factor (CTGF), and CCN5/WISP2, were among the most significantly up-regulated genes. We further investigated the role of CCN1/Cyr61 in Wnt3A-regulated osteogenic differentiation. We confirmed that CCN1/Cyr61 was up-regulated at the early stage of Wnt3A stimulation. Chromatin immunoprecipitation analysis indicates that CCN1/Cyr61 is a direct target of canonical Wnt/beta-catenin signaling. RNA interference-mediated knockdown of CCN1/Cyr61 expression diminished Wnt3A-induced osteogenic differentiation. Furthermore, exogenously expressed CCN1/Cyr61 was shown to effectively promote mesenchymal stem cell migration. These findings suggest that tightly regulated CCN1/Cyr61 expression may play an important role in Wnt3A-induced osteoblast differentiation of mesenchymal stem cells.

Adenoviridae↗
PubMed2005

An orthotopic model of human osteosarcoma growth and spontaneous pulmonary metastasis.

Osteosarcoma is the most common primary malignancy of bone and patients often develop pulmonary metastases. In order to investigate the pathogenesis of human osteosarcoma, there is a great need to develop a clinically relevant animal model. Here we report the development of an osteosarcoma animal model using three related human osteosarcoma lines, the parental TE-85 and two derivative lines MNNG/HOS and 143B. In vitro characterization demonstrated that the 143B line had the greatest cell migration and the least cell adhesion activities among the three lines. The 143B line also exhibited the greatest ability for anchorage independent growth. When GFP-tagged osteosarcoma cells were injected into the proximal tibia of athymic mice, we found that 143B cells were highly tumorigenic and metastatic, and MNNG/HOS cells were tumorigenic but significantly less metastatic. TE85 cells were neither tumorigenic nor metastatic. The number of pulmonary metastases was found 50-fold higher in 143B injected animals than that in MNNG/HOS injected mice. No pulmonary metastases were detected in TE85 injected animals for up to 8 weeks. Primary tumors formed by MNNG/HOS and 143B cells could be visualized by whole body fluorescence imaging, while the pulmonary metastases were visualized on the necropsied samples. The GFP tagged 143B cells (and to a lesser extent, MNNG/HOS cells) were readily recovered from lung metastases. This clinically relevant model of human osteosarcoma provides varying degrees of tumor growth at the primary site and metastatic potential. Thus, this orthotopic model should be a valuable tool to investigate factors that promote or inhibit osteosarcoma growth and/or metastasis.

Animals↗
PubMed2005

Characterization of adenovirus-mediated gene transfer in rabbit flexor tendons.

PURPOSE: Adenoviral vector-based gene therapy is a promising technique for the delivery of growth factors to tendons. The objective of this study was to determine whether rabbit flexor tendons could be transduced effectively by adenoviral vectors and whether the introduction of adenoviral vectors would cause a notable local inflammatory response. METHODS: Recombinant adenoviruses expressing green fluorescent protein (AdGFP) or BMP-13 (AdBMP-13) were constructed and 3 different viral titers (1 x 10(7), 1 x 10(8), and 1 x 10(9)) were tested in this study. The second through fifth tendons of the forepaws and hindpaws of a New Zealand white rabbit were identified surgically and injected with different viral titers of adenoviruses. The fifth tendon was used as a control. The tendons were harvested 12 days after surgery. The retrieved tendons were sectioned to measure transgene expression, as well as for histologic evaluation. RESULTS: At all tested viral titers an efficient dose-dependent transgene expression was detected in all samples at 12 days after injection. At the highest dose the injection sites were notable for lymphocytic infiltration, suggesting that injected adenoviral vectors can illicit some local inflammatory response. Lymphocytic infiltration was much less apparent, however, in the tendons injected with lower titers of adenoviral vectors. There was no evidence of a massive inflammatory response and/or cell death. CONCLUSIONS: Our findings show that adenovirus-based gene therapy is an efficient means of gene delivery to rabbit flexor tendons. Transduction efficiency of transgenes was dose dependent across the tested titers, although adenovirus-induced inflammation was notable only at the highest titer. This indicates that efficient gene transfer without notable local inflammatory response may be achieved by using the lower titers. Although adenovirus-induced inflammation can be minimized by using lower viral titers, its impact on adhesion formation in the long term remains unknown.

Adenoviridae↗
PubMed2005

Gene therapy for bone regeneration.

Efficacious bone regeneration could revolutionize the clinical management of many bone and musculoskeletal disorders. Bone has the unique ability to regenerate and continuously remodel itself throughout life. However, clinical situations arise when bone is unable to heal itself, as with segmental bone loss, fracture non-union, and failed spinal fusion. This leads to significant morbidity and mortality. Current attempts at improved bone healing have been met with limited success, fueling the development of improved techniques. Gene therapy in many ways represents an ideal approach for augmenting bone regeneration. Gene therapy allows specific gene products to be delivered to a precise anatomic location. In addition, the level of transgene expression as well as the duration of expression can be regulated with current techniques. For bone regeneration, the gene of interest should be delivered to the fracture site, expressed at appropriate levels, and then deactivated once the fracture has healed. Delivery of biological factors, mostly bone morphogenetic proteins (BMPs), has yielded promising results both in animal and clinical studies. There has also been tremendous work on discovering new growth factors and exploring previously defined ones. Finally, significant advances are being made in the delivery systems of the genes, ranging from viral and non-viral vectors to tissue engineering scaffolds. Despite some public hesitation to gene therapy, its use has great potential to expand our ability to treat a variety of human bone and musculoskeletal disorders. It is conceivable that in the near future gene therapy can be utilized to induce bone formation in virtually any region of the body in a minimally invasive manner. As bone biology and gene therapy research progresses, the goal of successful human gene transfer for augmentation of bone regeneration draws nearer.

Animals↗
PubMed2005

[Protection of mdr1 transfected cord blood mononuclear cell graft against anticancer agents in vivo].

OBJECTIVE: To explore the myelo-protection effect of mdr1 transfected cord blood cells (CBMNCs) graft against high-dose homoharringtonine leukemia-bearing severe combined immunodeficient (SCID) mice model. METHODS: Multidrug resistant (mdr1)gene was transferred into CBMNCs by a retrovirus vector, containing full-length cDNA of human mdr1 gene. CBMNCs and high-titer retrovirus supernatant were cocultured with cytokine combinations for 5 - 6 days. The SCID mouse models bearing human HL-60 cell leukemia were divided into three groups. Group A received tail vein injection of 2 x 10(6) mdr1 gene transduced CBMNCs at day 1 and 3, groups B and C 2 x 10(6) un-transduced CBMNCs and same volume of normal saline, respectively. The 3 groups of the mouse model were treated with weekly escalated doses of homoharringtonine. The peripheral white blood cell (WBC) counts, the human leukemia cells percentage in peripheral blood, the histological findings of main organs were assayed. The CD33 positive HL-60 cells in bone marrow were determined by flow cytometry. The function and expression of mdr1 gene were examined by PCR, immunochemistry (IC) and DNR extrusion test in vivo. RESULTS: (1) mdr1 gene was transferred into CBMNCs successfully and the transfection frequency was 30%. (2) Leukemia SCID mice were xenotransplanted with mdr1-transfected BMMNCs by a programmed procedure and could be used as a valuable model for in vivo evaluating myelo-protection effects. (3) The transfected mice could tolerate homoharringtonine 5 approximately 6 folds higher than conventional dose and kept peripheral WBC count at a mean of 3 x 10(9)/L, with the peripheral human myeloid leukemia cells percentage decreasing to less than 5%. Histological examination showed that there was no leukemia infiltration in the main organs, the CD33 positive HL-60 cells in bone marrow were less than 5%. (4) The repopulation frequency of the transfected CBMNs in marrow were 9.13%. DNR extrusion test confirmed that the P-gp product maintained its biological function in the marrow. CONCLUSION: mdr1 transferred-human CBMNC can xenotransplanted and repopulated in leukemia-bearing SCID mouse and are protected from chemotherapy-induced myelosuppression.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Connective tissue growth factor (CTGF) is regulated by Wnt and bone morphogenetic proteins signaling in osteoblast differentiation of mesenchymal stem cells.

Osteoblast lineage-specific differentiation of mesenchymal stem cells is a well regulated but poorly understood process. Both bone morphogenetic proteins (BMPs) and Wnt signaling are implicated in regulating osteoblast differentiation and bone formation. Here we analyzed the expression profiles of mesenchymal stem cells stimulated with Wnt3A and osteogenic BMPs, and we identified connective tissue growth factor (CTGF) as a potential target of Wnt and BMP signaling. We confirmed the microarray results, and we demonstrated that CTGF was up-regulated at the early stage of BMP-9 and Wnt3A stimulations and that Wnt3A-regulated CTGF expression was beta-catenin-dependent. RNA interference-mediated knockdown of CTGF expression significantly diminished BMP-9-induced, but not Wnt3A-induced, osteogenic differentiation, suggesting that Wnt3A may also regulate osteoblast differentiation in a CTGF-independent fashion. However, constitutive expression of CTGF was shown to inhibit both BMP-9- and Wnt3A-induced osteogenic differentiation. Exogenous expression of CTGF was shown to promote cell migration and recruitment of mesenchymal stem cells. Our findings demonstrate that CTGF is up-regulated by Wnt3A and BMP-9 at the early stage of osteogenic differentiation, which may regulate the proliferation and recruitment of osteoprogenitor cells; however, CTGF is down-regulated as the differentiation potential of committed pre-osteoblasts increases, strongly suggesting that tight regulation of CTGF expression may be essential for normal osteoblast differentiation of mesenchymal stem cells.

Adenoviridae↗
PubMed2004

Inhibitor of DNA binding/differentiation helix-loop-helix proteins mediate bone morphogenetic protein-induced osteoblast differentiation of mesenchymal stem cells.

Bone morphogenetic proteins (BMPs) belong to the TGF-beta superfamily and play an important role in development and in many cellular processes. We have found that BMP-2, BMP-6, and BMP-9 induce the most potent osteogenic differentiation of mesenchymal stem cells. Expression profiling analysis has revealed that the Inhibitors of DNA binding/differentiation (Id)-1, Id-2, and Id-3 are among the most significantly up-regulated genes upon BMP-2, BMP-6, or BMP-9 stimulation. Here, we sought to determine the functional role of these Id proteins in BMP-induced osteoblast differentiation. We demonstrated that the expression of Id-1, Id-2, and Id-3 genes was significantly induced at the early stage of BMP-9 stimulation and returned to basal levels at 3 days after stimulation. RNA interference-mediated knockdown of Id expression significantly diminished the BMP-9-induced osteogenic differentiation of mesenchymal progenitor cells. Surprisingly, a constitutive overexpression of these Id genes also inhibited osteoblast differentiation initiated by BMP-9. Furthermore, we demonstrated that BMP-9-regulated Id expression is Smad4-dependent. Overexpression of the three Id genes was shown to promote cell proliferation that was coupled with an inhibition of osteogenic differentiation. Thus, our findings suggest that the Id helix-loop-helix proteins may play an important role in promoting the proliferation of early osteoblast progenitor cells and that Id expression must be down-regulated during the terminal differentiation of committed osteoblasts, suggesting that a balanced regulation of Id expression may be critical to BMP-induced osteoblast lineage-specific differentiation of mesenchymal stem cells.

Adenoviridae↗
PubMed2004

Wnt/beta-catenin signaling pathway as a novel cancer drug target.

Wnt proteins are a large family of secreted glycoproteins. Wnt proteins bind to the Frizzled receptors and LRP5/6 co-receptors, and through stabilizing the critical mediator beta-catenin, initiate a complex signaling cascade that plays an important role in regulating cell proliferation and differentiation. Deregulation of the canonical Wnt/beta-catenin signaling pathway, mostly by inactivating mutations of the APC tumor suppressor, or oncogenic mutations of beta-catenin, has been implicated in colorectal tumorigenesis. Although oncogenic mutations of beta-catenin have only been discovered in a small fraction of non-colon cancers, elevated levels of beta-catenin protein, a hallmark of activated canonical Wnt pathway, have been observed in most common forms of human malignancies, indicating that activation of this pathway may play an important role in tumor development. Over the past 15 years, our understanding of this signaling pathway has significantly improved with the identification of key regulatory proteins and the important downstream targets of beta-catenin/Tcf transactivation complex. Given the fact that Wnt/beta-catenin signaling is tightly regulated at multiple cellular levels, the pathway itself offers ample targeting nodal points for cancer drug development. In this review, we discuss some of the strategies that are being used or can be explored to target key components of the Wnt/beta-catenin signaling pathway in rational cancer drug discovery.

Animals↗
PubMed2003

Transcriptional characterization of bone morphogenetic proteins (BMPs)-mediated osteogenic signaling.

Bone formation is presumably a complex and well-orchestrated process of osteoblast lineage-specific differentiation. As members of the TGFbeta superfamily, bone morphogenetic proteins (BMPs) play an important role in regulating osteoblast differentiation and subsequent bone formation. Several BMPs are able to induce de novo bone formation. Although significant progress has recently been made about the transcriptional control of osteoblast differentiation, detailed molecular events underlying the osteogenic process remain to be elucidated. In order to identify potentially important signaling mediators activated by osteogenic BMPs but not by non-osteogenic BMPs, we sought to determine the transcriptional differences between three osteogenic BMPs (i.e., BMP-2, BMP-6, and BMP-9) and two inhibitory/non-osteogenic BMPs (i.e., BMP-3 and BMP-12). Through the microarray analysis of approximately 12,000 genes in pre-osteoblast progenitor cells, we found that expression level of 203 genes (105 up-regulated and 98 down-regulated) was altered >2-fold upon osteogenic BMP stimulation. Gene ontology analysis revealed that osteogenic BMPs, but not inhibitory/non-osteogenic BMPs, activate genes involved in the proliferation of pre-osteoblast progenitor cells towards osteoblastic differentiation, and simultaneously inhibit myoblast-specific gene expression. BMP-regulated expression of the selected target genes was confirmed by RT-PCR, as well as by the CodeLink Bioarray analysis. Our findings are consistent with the notion that osteogenesis and myogenesis are two divergent processes. Further functional characterization of these downstream target genes should provide important insights into the molecular mechanisms behind BMP-mediated bone formation.

Adenoviridae↗
PubMed2002

[Expression of Mdr1 gene in a murine bone marrow transplantation model].

OBJECTIVE: To investigate the expression of mdr1 gene in hematopoietic cells of a murine bone marrow transplantation model and to explore the feasibility of transferring mdr1 gene into hematopoietic cells to pro-vent myelosuppression from chemotherapy. METHODS: mdr1 gene was transferred into hematopoietic cells of murine bone marrow by retrovirus vector. The expression and function of mdr1 gene in vivo was tested in a murine bone marrow transplantation model. RESULTS: (1) mdr1 gene was successfully transferred into murine MNC, the transduction rate was 35%. (2) mdr1 gene transferred murine bone marrow transplantation model was established successfully by scheduled-bone marrow transplantation method. (3) In 1 approximately 5 months period, stable and effective expression of mdr1 gene could be detected in hematopoietic cells of the recipient mouse, the percentage of mdr1 gene expression cells in recipient's hematopoietic cells decreased monthly to 8.0%, 8.0%, 7.5%, 4.0% and 3.0%. (4) mdr1 expression hematopoietic cells had efficient resistance to chemotherapy. CONCLUSION: It is an effective approach to transfer mdr1 gene into hematopoietic cells for preventing myelosuppression in chemotherapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗