Biomedical subjects

Yibin Kang

Publications and source records attributed to Yibin Kang.

15 recordsLinked to original sources

PubMed2026

Host metadherin coordinates hepatic lipid metabolism and CD8+ T cell immunity to promote tumor progression.

Cancer progression is systemically influenced by distant organ dysfunction induced by primary tumors, yet how long-distance tumor-organ crosstalk regulates antitumor immunity remains unclear. Here, we identify host metadherin (MTDH) as a critical regulator of tumor-induced immunosuppression and metabolic reprogramming via tumor-liver interactions. Using Mtdh knockout mouse models, we show that concurrent MTDH loss in hepatocytes and CD8+ T cells enhances effector T cell function and suppresses tumor growth and metastasis. Mechanistically, tumor-derived extracellular vesicles and particles (EVPs) activate Kupffer cells to secrete tumor necrosis factor α (TNF-α) and TGF-β, which suppress hepatic PPARα-mediated lipid oxidation via nuclear factor κB (NF-κB) signaling. MTDH loss restores hepatic lipid catabolism, reduces systemic lipid levels, and promotes mitochondrial metabolic reprogramming in CD8+ T cells under lipid-reduced conditions, thereby boosting antitumor immunity. Genetic or pharmacological targeting of MTDH synergizes with anti-PD-1 therapy. These findings establish host MTDH as a key mediator of tumor-liver crosstalk through metabolic and immune interactions, driving systemic cancer progression.

CD8(+) T cells↗

PubMed2025

Tumors hijack macrophages for iron supply to promote bone metastasis and anemia.

Bone marrow is both a primary site for hematopoiesis and a fertile niche for metastasis. The mechanism of the common occurrence of anemia among patients with bone metastasis remains poorly understood. Here, we show that a specialized population of VCAM1+CD163+CCR3+ macrophages, normally essential for erythropoiesis by transporting iron to erythroblasts, are highly enriched in the bone metastatic niche in mouse models. Tumor cells hijack these macrophages for iron supply, reducing iron availability for erythroblasts, impairing erythropoiesis, and contributing to anemia. Increased iron supply enables tumor cells to produce hemoglobin in response to hypoxia, mimicking erythroblasts. We identify macrophages with similar iron-transporting features in human bone metastases and show that elevated HBB expression correlates with increased risk of bone metastasis. These findings establish iron-transporting macrophages as an essential component of the metastatic bone niche, revealing a critical interplay between immune cells, metal metabolism, and tumor cell plasticity in driving metastasis and anemia.

Animals↗

PubMed2007

Beyond tumorigenesis: cancer stem cells in metastasis.

The importance of cancer stem cells (CSCs) in tumor-initiation has been firmly established in leukemia and recently reported for a variety of solid tumors. However, the role of CSCs in multistage cancer progression, particularly with respect to metastasis, has not been well-defined. Cancer metastasis requires the seeding and successful colonization of specialized CSCs at distant organs. The biology of normal stem cells and CSCs share remarkable similarities and may have important implications when applied to the study of cancer metastasis. Furthermore, overlapping sets of molecules and pathways have recently been identified to regulate both stem cell migration and cancer metastasis. These molecules constitute a complex network of cellular interactions that facilitate both the initiation of the pre-metastasis niche by the primary tumor and the formation of a nurturing organ microenvironment for migrating CSCs. In this review, we surveyed the recent advances in this dynamic field and propose a unified model of cancer progression in which CSCs assume a central role in both tumorigenesis and metastasis. Better understanding of CSCs as a fundamental component of the metastatic cascade will lead to novel therapeutic strategies against metastatic cancer.

Animals↗

PubMed2006

Pro-metastasis function of TGFbeta mediated by the Smad pathway.

The transforming growth factor beta (TGFbeta) signaling pathway plays a vital role in the development and homeostasis of normal tissues. Abnormal function of this pathway contributes to the initiation and progression of cancer. Smad proteins are key signal transducers of the TGFbeta pathway and are essential for the growth suppression function of TGFbeta. Smads are bona fide tumor suppressors whose mutation, deletion, and silencing are associated with many types of human cancer. However, the involvement and functional mechanism of Smad proteins in cancer metastasis are poorly defined. Recent studies using genetically modified cancer cells and mouse tumor models have provided concrete evidence for a Smad-dependent mechanism for metastasis promotion by TGFbeta. Understanding the dual roles of Smad proteins in tumor initiation and progression has important implications for cancer therapeutics.

Animals↗

PubMed2005

Breast cancer bone metastasis mediated by the Smad tumor suppressor pathway.

TGF-beta can signal by means of Smad transcription factors, which are quintessential tumor suppressors that inhibit cell proliferation, and by means of Smad-independent mechanisms, which have been implicated in tumor progression. Although Smad mutations disable this tumor-suppressive pathway in certain cancers, breast cancer cells frequently evade the cytostatic action of TGF-beta while retaining Smad function. Through immunohistochemical analysis of human breast cancer bone metastases and functional imaging of the Smad pathway in a mouse xenograft model, we provide evidence for active Smad signaling in human and mouse bone-metastatic lesions. Genetic depletion experiments further demonstrate that Smad4 contributes to the formation of osteolytic bone metastases and is essential for the induction of IL-11, a gene implicated in bone metastasis in this mouse model system. Activator protein-1 is a key participant in Smad-dependent transcriptional activation of IL-11 and its overexpression in bone-metastatic cells. Our findings provide functional evidence for a switch of the Smad pathway, from tumor-suppressor to prometastatic, in the development of breast cancer bone metastasis.

Animals↗

PubMed2005

Distinct organ-specific metastatic potential of individual breast cancer cells and primary tumors.

We used bioluminescence imaging to reveal patterns of metastasis formation by human breast cancer cells in immunodeficient mice. Individual cells from a population established in culture from the pleural effusion of a breast cancer patient showed distinct patterns of organ-specific metastasis. Single-cell progenies derived from this population exhibited markedly different abilities to metastasize to the bone, lung, or adrenal medulla, which suggests that metastases to different organs have different requirements. Transcriptomic profiling revealed that these different single-cell progenies similarly express a previously described "poor-prognosis" gene expression signature. Unsupervised classification using the transcriptomic data set supported the hypothesis that organ-specific metastasis by breast cancer cells is controlled by metastasis-specific genes that are separate from a general poor-prognosis gene expression signature. Furthermore, by using a gene expression signature associated with the ability of these cells to metastasize to bone, we were able to distinguish primary breast carcinomas that preferentially metastasized to bone from those that preferentially metastasized elsewhere. These results suggest that the bone-specific metastatic phenotypes and gene expression signature identified in a mouse model may be clinically relevant.

Animals↗

PubMed2005

Functional genomic analysis of cancer metastasis: biologic insights and clinical implications.

Metastasis, the spread of cancer from primary tumors to distant vital organs, has devastating consequences. Lack of effective tools to study this complex problem has hindered the development of accurate prognostic methods and effective treatments for metastatic cancer. In the postgenomic era, the application of genomic profiling methods to the analysis of clinical metastasis samples and animal metastasis models has revolutionized the field of metastasis research. This article reviews recent breakthroughs in the functional genomic analysis of metastasis. In addition, its impacts on our understanding of the molecular basis of metastasis and on clinical practice are discussed.

Animals↗

PubMed2004

Epithelial-mesenchymal transitions: twist in development and metastasis.

Epithelial-mesenchymal transitions (EMT) are vital for morphogenesis during embryonic development and are also implicated in the conversion of early stage tumors into invasive malignancies. Several key inducers of EMT are transcription factors that repress E-cadherin expression. A recent report in Cell (Yang et al., 2004) adds Twist to this list and links EMT to the ability of breast cancer cells to enter the circulation and seed metastases.

Animals↗

PubMed2004

Comparative functional characterization of the feline foamy virus transactivator reveals its species specificity.

Foamy virus (FV) Bel1/Tas transactivators act as key regulators of gene expression and directly bind DNA Bel1 response elements (BREs) in both the internal (IP) and 5'LTR promoters. Here, we report the mapping and the virus species specificity of the nonhomologous feline foamy virus (FFV) BREs in both promoters. The data indicate that FFV Bel1 did not bind the primate FV IP.BRE and that primate FV Bel1 was not capable of binding the FFV IP.BRE. In addition, we show that the C-terminal activation domain of FFV Bel1 does not contribute to DNA binding because a C-terminal trans-dominant negative FFV Bel1 mutant was still able to bind to both promoters.

5' Untranslated Regions↗

PubMed2003

A self-enabling TGFbeta response coupled to stress signaling: Smad engages stress response factor ATF3 for Id1 repression in epithelial cells.

Genome-wide transcriptional profiling of human epithelial cells revealed that repression of Id inhibitors of differentiation (Id1, Id2, and Id3) is a general feature of the TGFbeta cytostatic program. Opposite responses of Id1 to TGFbeta and the related factor BMP are dictated by the specific ability of the TGFbeta mediator, Smad3, to activate expression of stress response factor ATF3 and then recruit this factor to the Id1 promoter. Thus, a Smad3-mediated primary gene response, ATF3 induction, enables Smad3 to participate in an ATF3-mediated, secondary gene response. As a common target of TGFbeta/Smad signals and stress signals via p38 kinase, ATF3 additionally serves to channel synergy between these pathways in the response of epithelial cells to stress and injury.

Activating Transcription Factor 3↗

PubMed2003

A multigenic program mediating breast cancer metastasis to bone.

We investigated the molecular basis for osteolytic bone metastasis by selecting human breast cancer cell line subpopulations with elevated metastatic activity and functionally validating genes that are overexpressed in these cells. These genes act cooperatively to cause osteolytic metastasis, and most of them encode secreted and cell surface proteins. Two of these genes, interleukin-11 and CTGF, encode osteolytic and angiogenic factors whose expression is further increased by the prometastatic cytokine TGF beta. Overexpression of this bone metastasis gene set is superimposed on a poor-prognosis gene expression signature already present in the parental breast cancer population, suggesting that metastasis requires a set of functions beyond those underlying the emergence of the primary tumor.

Animals↗

PubMed2002

E2F4/5 and p107 as Smad cofactors linking the TGFbeta receptor to c-myc repression.

Smad3 is a direct mediator of transcriptional activation by the TGFbeta receptor. Its target genes in epithelial cells include cyclin-dependent kinase inhibitors that generate a cytostatic reponse. We defined how, in the same context, Smad3 can also mediate transcriptional repression of the growth-promoting gene c-myc. A complex containing Smad3, the transcription factors E2F4/5 and DP1, and the corepressor p107 preexists in the cytoplasm. In response to TGFbeta, this complex moves into the nucleus and associates with Smad4, recognizing a composite Smad-E2F site on c-myc for repression. Previously known as the ultimate recipients of cdk regulatory signals, E2F4/5 and p107 act here as transducers of TGFbeta receptor signals upstream of cdk. Smad proteins therefore mediate transcriptional activation or repression depending on their associated partners.

Active Transport, Cell Nucleus↗

PubMed2002

The crystal structure and mutational analysis of a novel RNA-binding domain found in the human Tap nuclear mRNA export factor.

The Tap protein mediates the sequence nonspecific nuclear export of cellular mRNAs as well as the sequence-specific export of retroviral mRNAs bearing the constitutive transport element (CTE). Previously, the structures of individual Tap subdomains, including ribonucleoprotein and leucine-rich repeat domains, have been described. Here, we report the crystal structure of a functional CTE RNA-binding domain of human Tap, including the N-terminal arm of the ribonucleoprotein domain and interdomain linking polypeptide. To identify residues that interact with the CTE, we have introduced 38 alanine substitutions for surface residues in the Tap CTE-binding domain and tested these mutants for their ability to support CTE-dependent nuclear RNA export and CTE binding. Four residues that cluster on a concave surface in the leucine-rich repeat domain were found to be critical for CTE binding and define a CTE-interacting surface on this domain. The second critical CTE-interacting surface on Tap is defined by three previously identified residues on the surface of the ribonucleoprotein domain. The structural and mutational data define a novel RNA-binding site on the Tap protein.

Amino Acid Motifs↗

PubMed2002

Smad2 nucleocytoplasmic shuttling by nucleoporins CAN/Nup214 and Nup153 feeds TGFbeta signaling complexes in the cytoplasm and nucleus.

The transcription factor Smad2 is released from cytoplasmic retention by TGFbeta receptor-mediated phosphorylation, accumulating in the nucleus where it associates with cofactors to regulate transcription. We uncovered direct interactions of Smad2 with the nucleoporins CAN/Nup214 and Nup153. These interactions mediate constitutive nucleocytoplasmic shuttling of Smad2. CAN/Nup214 and Nup153 compete with the cytoplasmic retention factor SARA and the nuclear Smad2 partner FAST-1 for binding to a hydrophobic corridor on the MH2 surface of Smad2. TGFbeta receptor-mediated phosphorylation stimulates nuclear accumulation of Smad2 by modifying its affinity for SARA and Smad4 but not for CAN/Nup214 or Nup153. Thus, by directly contacting the nuclear pore complex, Smad2 undergoes constant shuttling, providing a dynamic pool that is competitively drawn by cytoplasmic and nuclear signal transduction partners.

3T3 Cells↗

PubMed2002

Formation of Tap/NXT1 heterodimers activates Tap-dependent nuclear mRNA export by enhancing recruitment to nuclear pore complexes.

The Tap protein has been shown to activate the nuclear export of mRNA species bearing retroviral constitutive transport elements and is also believed to play an essential role in the sequence nonspecific export of cellular mRNAs. However, it has remained unclear how Tap activity is regulated in vivo. Here, we report that the small NXT1/p15-1 protein functions as a critical cofactor for Tap-mediated mRNA export in both human and invertebrate cells. In the absence of NXT1 binding, the Tap protein is unable to effectively interact with components of the nuclear pore complex and both Tap nucleocytoplasmic shuttling and the nuclear export of mRNA molecules tethered to Tap are therefore severely attenuated. Formation of a Tap/NXT1 heterodimer enhances nucleoporin binding both in vitro and in vivo and induces the formation of a Tap/NXT1/nucleoporin ternary complex that is likely to be a key intermediate in the process of nuclear mRNA export. The critical importance of NXT1 for the nuclear export of poly(A)(+) RNA is emphasized by the finding that specific inhibition of the expression of the Drosophila homolog of human NXT1, by using RNA interference, results in the nuclear accumulation of poly(A)(+) RNA in cultured insect cells. These data suggest that NXT1 may act as a molecular switch that regulates the ability of Tap to mediate nuclear mRNA export by controlling the interaction of Tap with components of the nuclear pore.

Active Transport, Cell Nucleus↗