Biomedical subjects

Rong Xiang

Publications and source records attributed to Rong Xiang.

At least 19 recordsLinked to original sources

PubMed2026

Integrative Genomic and Functional Investigation of the Multi-Layered Genetic Architecture Between Anorexia Nervosa and Bone Loss.

OBJECTIVE: Bone loss is a severe and often irreversible complication of anorexia nervosa (AN), yet the genetic mechanisms underlying this comorbidity remain underexplored. This study focuses on constructing a comprehensive genetic architecture between AN and estimated calcaneal bone mineral density (eBMD). METHOD: We applied an integrative framework incorporating genetic correlation, pleiotropic association, and causal inference across single-variant, multi-variant, and gene expression levels. Functional validation was conducted in vitro to investigate the biological role of the key candidate gene. RESULTS: Local genetic correlation analysis identified significant signals at 8p21.2 and 10q26.3, despite the lack of significant global correlation. Mendelian randomization analysis pointed to a suggestive negative causal effect of genetically predisposed AN on eBMD. Extensive pleiotropic signals were detected, particularly at 3p21.31 and 10q26.3, loci enriched with genes associated with both traits. Notably, we identified a novel pleiotropic signal near NCAM1 at 11q23.2, which was supported by multi-layered genetic evidence and confirmed through in vitro functional experiments. NCAM1, a well-established neural-associated gene, promoted osteoclastic differentiation and bone resorption when overexpressed in osteoclast precursor cells, indicating that NCAM1 possesses distinct functional roles in both neural and skeletal tissues. DISCUSSION: This study constructs a comprehensive genetic architecture underlying AN and eBMD and highlights NCAM1 as a key pleiotropic gene.

anorexia nervosa↗

PubMed2006

FLK-1-based minigene vaccines induce T cell-mediated suppression of angiogenesis and tumor protective immunity in syngeneic BALB/c mice.

Angiogenesis is a rate-limiting step in the development of tumors. Here, we demonstrate that oral minigene DNA vaccines against murine vascular endothelial growth factor receptor-2 (FLK-1), a self-antigen overexpressed on proliferating endothelial cells in the tumor vasculature, induced protection against tumors of different origin in syngeneic BALB/c mice. This protection is mediated by CD8 T cells, which specifically kill FLK-1(+) endothelial cells, resulting in marked suppression of tumor angiogenesis. More importantly, the minigene vaccine proved to be of similar efficacy as a vaccine encoding the whole FLK-1 gene. These data suggest a FLK-1 minigene vaccine provides a more flexible alternative to the whole gene vaccine and will facilitate their future design and clinical applications in cancer therapy and prevention.

Administration, Oral↗

PubMed2006

Characterization of stem cell-like cancer cells in immune-competent mice.

Recently, the cancer stem cell hypothesis has gained significant recognition as the descriptor of tumorigenesis. Although previous studies relied on transplanting human or rat tumor cells into immunecompromised mice, our study used the Hoechst 33342 dye-based side population (SP) technique to isolate and transplant stem cell-like cancer cells (SCLCCs) from the 4T1 and NXS2 murine carcinoma cell lines into the immune-competent microenvironment of syngeneic mice. 4T1 cells displayed an SP of 2% with a Sca-1(high)c-Kit(-)CD45(-) phenotype, whereas NXS2 cells contained an SP of 0.2% with a Sca-1(high)CD24(high)c-Kit(-)CD45(-)GD (high)(2) phenotype. Reverse transcription-polymerase chain reaction (RT-PCR) further revealed up-regulation in SP cells of ABCG2, Sca-1, Wnt-1, and TGF-beta2. Additionally, 4T1 and NXS2 SP cells exhibited increased resistance to chemotherapy, and 4T1 SP cells also showed an increased ability to efflux doxorubicin, which correlated with a selective increase in the percentage of SP cells found in the tumors of doxorubicin-treated mice. Most importantly, SP cells showed a markedly higher repopulation and tumorigenic potential in vivo, which correlated with an increased number of cells in the SP compartment of SP-derived tumors. Taken together, these results show that we successfully characterized SCLCCs from 2 murine carcinoma cell lines in the immune-competent microenvironment of syngeneic mice.

Animals↗

PubMed2006

A novel DNA vaccine encoding PDGFRbeta suppresses growth and dissemination of murine colon, lung and breast carcinoma.

Over the past several years it has become apparent that the tumor stroma represents a significant target for anti-cancer therapies. Therefore we evaluated the strategy of targeting the tumor stroma with a novel DNA vaccine encoding murine platelet derived growth factor receptor-beta (mPDGFRbeta). Immunization with this vaccine induced cytotoxic lysis of mPDGFRbeta-expressing target cells and protected mice from the growth and dissemination of murine colon, breast and lung carcinoma. Furthermore, this novel vaccine suppresses angiogenesis in vivo and reduces the numbers of tumor-associated, mPDGFRbeta-expressing pericytes as suggested by a decrease in intra-tumoral expression of mPDGFRbeta and NG2.

Administration, Oral↗

PubMed2006

Endoglin (CD105) is a target for an oral DNA vaccine against breast cancer.

Endoglin (CD105), a co-receptor in the TGF-beta receptor complex, is over-expressed on proliferating endothelial cells in the breast tumor neovasculature and thus offers an attractive target for anti-angiogenic therapy. Here we report the anti-angiogenic/anti-tumor effects achieved in a prophylactic setting with an oral DNA vaccine encoding murine endoglin, carried by double attenuated Salmonella typhimurium (dam-, AroA-) to a secondary lymphoid organ, i.e., Peyer's patches . We demonstrate that an endoglin vaccine elicited activation of antigen-presenting dendritic cells, coupled with immune responses mediated by CD8+ T cells against endoglin-positive target cells. Moreover, we observed suppression of angiogenesis only in mice administered with the endoglin vaccine as compared to controls. These data suggest that a CD8+ T cell-mediated immune response induced by this vaccine effectively suppressed dissemination of pulmonary metastases of D2F2 breast carcinoma cells presumably by eliminating proliferating endothelial cells in the tumor vasculature. It is anticipated that vaccine strategies such as this may contribute to future therapies for breast cancer.

Administration, Oral↗

PubMed2006

Nod1-dependent control of tumor growth.

Nod1, a cytosolic protein that senses meso-diaminopimelic acid-containing ligands derived from peptidoglycan, plays a role in host responses to invasive bacteria. Here we describe a function for Nod1, whereby it controls tumor formation. Cell lines derived from the human breast cancer epithelial cell line MCF-7 were used in a severe combined immune deficiency (SCID) mouse xenograft model to characterize a pathway linking Nod1 to the growth of estrogen-sensitive tumors. In MCF-7 cells, the absence of Nod1 correlates with tumor growth, an increased sensitivity to estrogen-induced cell proliferation, and a failure to undergo Nod1-dependent apoptosis. Conversely, overexpression of Nod1 in MCF-7 cells results in inhibition of estrogen-dependent tumor growth and reduction of estrogen-induced proliferative responses in vitro.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Targeting cell-impermeable prodrug activation to tumor microenvironment eradicates multiple drug-resistant neoplasms.

The tumor microenvironment is notably enriched with a broad spectrum of proteases. The proteolytic specificities of peptide substrates provide modular chemical tools for the rational design of cell-impermeable prodrugs that are specifically activated by proteases extracellularly in the tumor microenvironment. Targeting cell-impermeable prodrug activation to tumor microenvironment will significantly reduce drug toxicity to normal tissues. The activated prodrug attacks both tumor and stroma cells through a "bystander effect" without selectively deleting target-producing cells, therefore further minimizing resistance and toxicity. Here, we showed that legumain, the only asparaginyl endopeptidase of the mammalian genome, is highly expressed by neoplastic, stromal, and endothelial cells in solid tumors. Legumain is present extracellularly in the tumor microenvironment, associated with matrix as well as cell surfaces and functional locally in the reduced pH of the tumor microenvironment. A novel legumain-activated, cell-impermeable doxorubicin prodrug LEG-3 was designed to be activated exclusively in the tumor microenvironment. Upon administration, there is a profound increase of the end-product doxorubicin in nuclei of cells in tumors but little in other tissues. This tumor microenvironment-activated prodrug completely arrested growth of a variety of neoplasms, including multidrug-resistant tumor in vivo and significantly extended survival without evidence of myelosuppression or cardiac toxicity. The tumor microenvironment-activated prodrug design can be extended to other proteases and chemotherapeutic compounds and provides new potentials for the rational development of more effective functionally targeted cancer therapeutics.

Animals↗

PubMed2006

Adaptor FADD is recruited by RTN3/HAP in ER-bound signaling complexes.

It has been well established that FADD plays a critical role in the membrane bound death-inducing signaling complexes. Herein, we report that endogenous FADD could interact with ectopic or endogenous RTN3/HAP. ER-bound RTN3 protein recruited endogenous FADD to the ER membrane and subsequently initiated caspase-8 cascade, including activation of caspase-8, processing of Bid and release of cytochrome c from mitochondria. Furthermore, we demonstrated that endogenous FADD was recruited by ER-bound endogenous RTN3 to the ER membrane under the tunicamycin stimulation. The dominant negative form of FADD containing DD could abolish these RTN3 generated events in the caspase-8 cascade. Moreover, we found that RTN3 induced caspase-9 processing was only partially resulted from caspase-8 activation (data unshown), indicating that multiple caspase cascades participated in the apoptosis from RTN3 over-expression. Furthermore, NogoB/ASY, a homologue of RTN3 and a potential RTN3 interacting protein, also associated with FADD and induced cytochrome c release in a FADD dependent manner.

Animals↗

PubMed2006

Targeting tumor-associated macrophages as a novel strategy against breast cancer.

Tumor-associated macrophages (TAMs) are associated with tumor progression and metastasis. Here, we demonstrate for the first time that legumain, a member of the asparaginyl endopeptidase family functioning as a stress protein, overexpressed by TAMs, provides an ideal target molecule. In fact, a legumain-based DNA vaccine served as a tool to prove this point, as it induced a robust CD8+ T cell response against TAMs, which dramatically reduced their density in tumor tissues and resulted in a marked decrease in proangiogenic factors released by TAMs such as TGF-beta, TNF-alpha, MMP-9, and VEGF. This, in turn, led to a suppression of both tumor angiogenesis and tumor growth and metastasis. Importantly, the success of this strategy was demonstrated in murine models of metastatic breast, colon, and non-small cell lung cancers, where 75% of vaccinated mice survived lethal tumor cell challenges and 62% were completely free of metastases. In conclusion, decreasing the number of TAMs in the tumor stroma effectively altered the tumor microenvironment involved in tumor angiogenesis and progression to markedly suppress tumor growth and metastasis. Gaining better insights into the mechanisms required for an effective intervention in tumor growth and metastasis may ultimately lead to new therapeutic targets and better anticancer strategies.

Animals↗

PubMed2005

A DNA-based cancer vaccine enhances lymphocyte cross talk by engaging the NKG2D receptor.

The NKG2D receptor is a stimulatory receptor expressed on NK cells and activated CD8 T cells. We previously demonstrated that engaging the NKG2D receptor markedly improved the efficacy of a survivin-based DNA vaccine. The combination vaccine, encoding both the NKG2D ligand H60 and survivin, activates innate and adaptive antitumor immunity and results in better protection against tumors of different origin and NKG2D expression levels. Here we demonstrate that the enhanced vaccine efficacy is in part attributable to increased cross talk between lymphocytes. Depletion of CD8 T cells during priming reduces the vaccine-induced activation of dendritic cells (DCs) and NK cell activity. Depletion of NK cells during priming leads to reduced DC activation and CTL activity. However, depletion of CD4 T cells results in the activation of DCs, NK cells, and CD8 T cells and enhances NK cell activity. The pH60/Survivin vaccine also increases DCs and NK cells but decreases CD4 T cell homing to Peyer patches, presumably as a result of changes in the homing receptor profile. Thus, by preferentially activating and attracting positive regulators and reducing negative regulators in Peyer patches, this dual-function DNA vaccine induces a microenvironment more suitable for NK cell activation and T cell priming.

Animals↗

PubMed2005

Fractalkine gene therapy for neuroblastoma is more effective in combination with targeted IL-2.

The induction of tumor protective immunity against neuroblastoma remains a major challenge for active immunotherapy. Fractalkine is a unique Th1 CX3C chemokine known to induce adhesion and migration of leukocytes mediated by both, a membrane-bound and soluble form, respectively. Here, we tested the hypothesis that chemokine gene therapy with fractalkine (FKN) induces an effective anti-neuroblastoma immune response amplified by targeted IL-2 using the anti-GD2 antibody ch14.18 fused with IL-2 (ch14.18-IL-2). For this purpose, NXS2 cells were genetically engineered to stably produce murine FKN (NXS2-FKN). Transcription and expression of the mFKN gene in tumor tissue of mice inoculated with NXS2-FKN cells were demonstrated in vivo. Importantly, mFKN exhibited a reduction in primary tumor growth and spontaneous liver metastases in syngenic A/J mice. This effect was boosted by targeted IL-2 using small non-curative doses of ch14-18-IL-2. The amplification of the FKN induced immune response was specific, since a non-specific antibody-IL-2 fusion protein ch225-IL-2 was ineffective. In summary, we demonstrated for the first time that chemokine gene therapy is amplified by targeted IL-2 suggesting a combination of both strategies as an adjuvant therapy for neuroblastoma.

Animals↗

PubMed2005

Tid1 negatively regulates the migratory potential of cancer cells by inhibiting the production of interleukin-8.

Tid1 is the human homologue of the Drosophila tumor suppressor, Tid56. Reducing the expression of Tid1 in MDA-MB231 breast cancer cells enhanced their migration without affecting their survival or growth rate. From microarray screening, we discovered that after Tid1 depletion, the mRNA level of interleukin-8 (IL-8) was significantly increased in these cancer cells, which consequently increased secretion of IL-8 protein by 3.5-fold. The enhanced migration of these Tid1-knockdown cells was blocked by reducing the IL-8 expression or by adding an IL-8 neutralizing antibody to the culture medium, suggesting that enhancement of cell motility in these Tid1-deficient cells is dependent on the de novo synthesis of IL-8. Subsequently, we found that abrogating the nuclear factor kappaB binding site in the IL-8 promoter completely blocked the Tid1 depletion-induced IL-8 expression in the breast cancer cells. As increased IL-8 levels are known to promote tumor metastasis, we tested the effect of Tid1 knockdown on tumor metastasis and found that Tid1 depletion enhanced the metastasis of breast cancer cells in animals. Together, these results indicate that Tid1 negatively regulates the motility and metastasis of breast cancer cells, most likely through attenuation of nuclear factor kappaB activity on the promoter of the IL8 gene.

Animals↗

PubMed2005

Therapeutic efficacy of tumor-targeted IL2 in LTalpha(-/-) mice depends on conditioned T cells.

An effective immunological eradication of tumors by the adaptive immune system depends on T cell priming, expansion of specific T cells and their effector function. It has been shown that either step may be impaired in the tumor-bearing host, and several strategies have been used to improve antitumor immune responses. In this regard, tumor-targeted IL2 therapy leads to the destruction of established melanoma metastases in fully immune competent mice as previously demonstrated. This effect has been attributed, but never directly confirmed, to the boost of antigen-experienced T cells. To this end, we demonstrate the absence of any antitumor effect of targeted IL2 in mice characterized by an impaired priming of T cell responses. Notably, in these animals tumor-targeted IL2 therapy induced tumor regression only after adoptive transfer of tumor-conditioned splenocytes. A detailed analysis revealed that T cells present within the transferred splenocytes were actively participating in the immune response as these were clonally expanded after targeted IL2 therapy. In summary, we demonstrate here that in LTalpha(-/-) mice lacking sufficient numbers of tumor-specific T cells only the passive transfer of such cells prior to therapy restores the efficacy of tumor-targeted IL2 therapy. Thus, the antitumor effect of tumor-targeted IL2 is indeed based on the boost of pre-existing T cell responses.

Animals↗

PubMed2005

DNA-based vaccines activate innate and adaptive antitumor immunity by engaging the NKG2D receptor.

The interaction of NKG2D, a stimulatory receptor expressed on natural killer (NK) cells and activated CD8(+) T cells, and its ligands mediates stimulatory and costimulatory signals to these cells. Here, we demonstrate that DNA-based vaccines, encoding syngeneic or allogeneic NKG2D ligands together with tumor antigens such as survivin or carcinoembryonic antigen, markedly activate both innate and adaptive antitumor immunity. Such vaccines result in highly effective, NK- and CD8(+) T cell-mediated protection against either breast or colon carcinoma cells in prophylactic and therapeutic settings. Notably, this protection was irrespective of the NKG2D ligand expression level of the tumor cells. Hence, this strategy has the potential to lead to widely applicable and possibly clinically useful DNA-based cancer vaccines.

Adaptation, Physiological↗

PubMed2005

T cell-mediated suppression of angiogenesis results in tumor protective immunity.

Antiangiogenic intervention is known to inhibit tumor growth and dissemination by attacking the tumor's vascular supply. Here, we report that this was achieved for the first time using an oral DNA minigene vaccine against murine vascular endothelial growth factor receptor 2 (FLK-1), a self-antigen overexpressed on proliferating endothelial cells in the tumor vasculature. Moreover, we identified the first H-2Db-restricted epitope, FLK400 (VILT-NPISM), specifically recognized by cytotoxic T lymphocytes (CTLs). Such CTLs were capable of killing FLK-1+ endothelial cells, resulting in suppression of angiogenesis and long-lived tumor protection. The specificity of this immune response was indicated because the DNA vaccine encoding the entire FLK-1 gene also induced a FLK400-specific CTL response. This minigene vaccine strategy provides a more flexible alternative to whole-gene vaccination and facilitates in-depth mechanism studies to tailor DNA vaccines for optimal T-cell activation and tumor protection.

Animals↗

PubMed2005

A DNA vaccine targeting Fos-related antigen 1 enhanced by IL-18 induces long-lived T-cell memory against tumor recurrence.

A novel vaccination strategy induced specific CD8(+) T cell-mediated immunity that eradicated spontaneous and experimental pulmonary cancer metastases in syngeneic mice and was also effective in a therapeutic setting of established breast cancer metastases. This was achieved by targeting transcription factor Fos-related antigen 1(Fra-1), overexpressed by many tumor cells, with an ubiquitinated DNA vaccine against Fra-1, coexpressing secretory IL-18. Insight into the immunologic mechanisms involved was provided by adoptive transfer of T lymphocytes from successfully immunized BALB/c mice to syngeneic severe combined immunodeficient (SCID) mice. Specifically, long-lived T memory cells were maintained dormant in nonlymphoid tissues by IL-18 in the absence of tumor antigen. Importantly, a second tumor cell challenge of these SCID mice restored both, robust tumor-specific cytotoxicity and long-lived T-cell memory, capable of eradicating established pulmonary cancer metastases, suggesting that this vaccine could be effective against tumor recurrence.

Animals↗

PubMed2005

Incorporation of single-wall carbon nanotubes into an organic polymer monolithic stationary phase for mu-HPLC and capillary electrochromatography.

Single-wall carbon nanotubes (SWNT) were incorporated into an organic polymer monolith containing vinylbenzyl chloride (VBC) and ethylene dimethacrylate (EDMA) to form a novel monolithic stationary phase for high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC). The retention behavior of neutral compounds on this poly(VBC-EDMA-SWNT) monolith was examined by separating a mixture of small organic molecules using micro-HPLC. The result indicated that incorporation of SWNT enhanced chromatographic retention of small neutral molecules in reversed-phase HPLC presumably because of their strongly hydrophobic characteristics. The stationary phase was formed inside a fused-silica capillary whose lumen was coated with covalently bound polyethyleneimine (PEI). The annular electroosmotic flow (EOF) generated by the PEI coating allowed peptide separation by CEC in the counterdirectional mode. Comparison of peptide separations on poly(VBC-EDMA-SWNT) and on poly(VBC-EDMA) with annular EOF generation revealed that the incorporation of SWNT into the monolithic stationary phase improved peak efficiency and influenced chromatographic retention. The structures of pretreated SWNT and poly(VBC-EDMA-SWNT) monolith were examined by high-resolution transmission electron microscopy, Raman spectroscopy, scanning electron microscopy, and multipoint BET nitrogen adsorption/desorption.

2-Propanol↗

PubMed2005

A DNA vaccine targeting survivin combines apoptosis with suppression of angiogenesis in lung tumor eradication.

A novel strategy achieved the eradication of lung tumor metastases by joint suppression of angiogenesis in the tumor neovasculature and induction of tumor cell apoptosis. This was accomplished by CTLs induced by a DNA vaccine encoding secretory chemokine CCL21 and the inhibitor of apoptosis protein survivin, overexpressed by both proliferating endothelial cells in the tumor vasculature and tumor cells. Oral delivery of this DNA vaccine by doubly attenuated Salmonella typhimurium (dam(-) and AroA(-)) to such secondary lymphoid organs as Peyer's patches in the small intestine, elicited marked activation of antigen-presenting dendritic cells, and an effective CD8(+)T cell immune response against the survivin self-antigen. This resulted in eradication or suppression of pulmonary metastases of non-small cell lung carcinoma in both prophylactic and therapeutic settings in C57BL/6J mice. Moreover, the suppression of angiogenesis induced by the vaccine did not impair wound healing or fertility of treated mice. It is anticipated that such novel DNA vaccines will aid in the rational design of future strategies for the prevention and treatment of cancer.

Animals↗