Browsing by Author "Chen, Daohong"

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    ANTXR1, a stem cell enriched functional biomarker, connects collagen signaling to cancer stem-like cells and metastasis in breast cancer
    (American Association for Cancer Research, 2013-09-15) Chen, Daohong; Bhat-Nakshatri, Poornima; Goswami, Chirayu; Badve, Sunil; Nakshatri, Harikrishna
    Cancer stem-like cells are thought to contribute to tumor recurrence. The anthrax toxin receptor ANTXR1 has been identified as a functional biomarker of normal stem cells and breast cancer stem-like cells. Primary stem cell-enriched basal cells (CD49f+/EpCAM−/Lin−) expressed higher levels of ANTXR1 compared to mature luminal cells. CD49f+/EpCAM−, CD44+/EpCAM−, CD44+/CD24− or ALDEFLUOR-positive subpopulations of breast cancer cells were enriched for ANTXR1 expression. CD44+/CD24−/ANTXR1+ cells displayed enhanced self-renewal as measured by mammosphere assay compared to CD44+/CD24−/ANTXR1− cells. Activation of ANTXR1 by its natural ligand C5A, a fragment of collagen VI α3, increased stem cell self-renewal in mammosphere assays and Wnt signaling including the expression of the Wnt receptor LRP6, phosphorylation of GSK3α/β and elevated expression of Wnt target genes. RNAi-mediated silencing of ANTXR1 enhanced the expression of luminal-enriched genes but diminished Wnt signaling including reduced LRP6 and ZEB1 expression, self-renewal, invasion, tumorigenicity and metastasis. ANTXR1 silencing also reduced the expression of HSPA1A, which is overexpressed in metastatic breast cancer stem cells. Analysis of public databases revealed ANTXR1 amplification in medullary breast carcinoma and overexpression in estrogen receptor-negative breast cancers with the worst outcome. Further, ANTXR1 is among the 10% most overexpressed genes in breast cancer and is co-expressed with collagen VI. Thus, ANTXR1:C5A interactions bridge a network of collagen cleavage and remodeling in the tumor microenvironment, linking it to a stemness signaling network drives metastatic progression.
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    Cancer impacts microRNA expression, release and function in cardiac and skeletal muscle
    (American Association for Cancer Research, 2014-08-15) Chen, Daohong; Goswami, Chirayu P; Burnett, Riesa M; Anjanappa, Manjushree; Bhat-Nakshatri, Poornima; Muller, William; Nakshatri, Harikrishna; Department of Surgery, IU School of Medicine
    Circulating microRNAs are emerging as important biomarkers of various diseases including cancer. Intriguingly, circulating levels of several microRNAs are lower in cancer patients compared with healthy individuals. In this study, we tested the hypothesis that a circulating microRNA might serve as a surrogate of the effects of cancer on microRNA expression or release in distant organs. Here we report that circulating levels of the muscle-enriched miR-486 is lower in breast cancer patients compared with healthy individuals, and that this difference is replicated faithfully in MMTV-PyMT and MMTV-Her2 transgenic mouse models of breast cancer. In tumor-bearing mice, levels of miR-486 were relatively reduced in muscle, where there was elevated expression of the miR-486 target genes PTEN and FOXO1A and dampened signaling through the PI3K/AKT pathway. Skeletal muscle expressed lower levels of the transcription factor MyoD which controls miR-486 expression. Conditioned media (CM) obtained from MMTV-PyMT and MMTV-Her2/Neu tumor cells cultured in vitro was sufficient to elicit reduced levels of miR-486 and increased PTEN and FOXO1A expression in C2C12 murine myoblasts. Cytokine analysis implicated TNFα and four additional cytokines as mediators of miR-486 expression in CM-treated cells. Since miR-486 is a potent modulator of PI3K/AKT signaling and the muscle-enriched transcription factor network in cardiac/skeletal muscle, our findings implicated TNFα-dependent miRNA circuitry in muscle differentiation and survival pathways in cancer.
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    CCCP-Induced LC3 Lipidation Depends on Atg9 Whereas FIP200/Atg13 and Beclin 1/Atg14 are Dispensable
    (Elsevier, 2013) Chen, Daohong; Chen, Xi; Li, Min; Zhang, Hao; Ding, Wen-Xing; Yin, Xiao-Ming; Pathology and Laboratory Medicine, School of Medicine
    Treatment of cells with carbonyl cyanide m-chlorophenylhydrazone (CCCP), a mitochondrial proton gradient uncoupler, can result in mitochondrial damage and autophagy activation, which in turn eliminates the injured mitochondria in a Parkin-dependent way. How CCCP mobilizes the autophagy machinery is not fully understood. By analyzing a key autophagy step, LC3 lipidation, we examined the roles of two kinase complexes typically involved in the initiation and nucleation phases of autophagy, namely the ULK kinase complex (UKC) and the Beclin 1/Atg14 complex. We found that CCCP-induced LC3 lipidation could be independent of Beclin 1 and Atg14. In addition, deletion or knockdown of the UKC component FIP200 or Atg13 only led to a partial reduction in LC3 lipidation, indicating that UKC could be also dispensable for this step during CCCP treatment. In contrast, Atg9, which is important for transporting vesicles to early autophagosomal structure, was required for CCCP-induced LC3 lipidation. Taken together, these data suggest that CCCP-induced autophagy and mitophagy depends more critically on Atg9 vesicles than on UKC and Beclin 1/Atg14 complex.