Heat shock protein 90-␣ (Hsp90␣) is an intracellular molecular chaperone. However, it can also be secreted with the underlying regulatory mechanism remaining far from clear. Here we show that the secreted Hsp90␣ is a C-terminal truncated form and its secretion is regulated by the C-terminal EEVD motif via interacting with proteins containing tetratricopeptide repeat domains. We also demonstrate that secretion of Hsp90␣ is determined by the phosphorylation status at residue Thr-90, regulated by protein kinase A and protein phosphatase 5. We further demonstrate that the secretion of Hsp90␣ is a prerequisite for its proinvasiveness function and blocking the secreted Hsp90␣ results in significant inhibition of tumor metastasis. Meanwhile, the level of plasma Hsp90␣ is positively correlated with tumor malignancy in clinical cancer patients. In sum, our results reveal the regulatory mechanism of Hsp90␣ secretion, and its function in tumor invasiveness, indicating it can be a promising diagnostic marker for tumor malignancy in clinical application.heat shock protein 90-␣ ͉ extracellular ͉ nonconventional protein secretion ͉ MMP-2 ͉ tumor marker

The mitochondrial adenosine triphosphate (ATP) synthase produces most of the ATP required by mammalian cells. We isolated porcine tetrameric ATP synthase and solved its structure at 6.2-angstrom resolution using a single-particle cryo–electron microscopy method. Two classical V-shaped ATP synthase dimers lie antiparallel to each other to form an H-shaped ATP synthase tetramer, as viewed from the matrix. ATP synthase inhibitory factor subunit 1 (IF1) is a well-known in vivo inhibitor of mammalian ATP synthase at low pH. Two IF1 dimers link two ATP synthase dimers, which is consistent with the ATP synthase tetramer adopting an inhibited state. Within the tetramer, we refined structures of intact ATP synthase in two different rotational conformations at 3.34- and 3.45-Å resolution.

BACKGROUND & AIMS:We aimed to identify long noncoding RNAs (lncRNAs) that are up-regulated in gastric cancer tissues from patients and study their function in gastric tumor metastasis. METHODS: We collected gastric tumor and nontumor tissues from patients in China and analyzed levels of lncRNAs by microarray analysis, proteins by immunohistochemistry, and RNAs by quantitative reverse-transcription polymerase chain reaction; we compared these with survival times of patients and tumor progression. RNA levels were knocked down or knocked out in BGC-823, SGC-7901, and MKN45 cell lines using small interfering or short hairpin RNAs or clustered regularly interspaced short palindromic repeats (ie, CRISPR)/CRISPR associated protein 9 (ie, Cas9) vectors. Genes were overexpressed from transfected plasmids in HGC-27 cells. Cells were analyzed by Northern blot and immunoblot, polysome profiling assay, and cell invasion assay. Cells were injected into the tail veins or spleens of nude mice or SCID mice; lung and liver tissues were collected, and metastases were counted. lncRNAs were cloned by using rapid amplification of complementary DNA ends. Their interactions with other genes were determined by RNA pulldown and mapping assays. RESULTS: In microarray analyses, we identified 151 lncRNAs expressed at significantly higher levels in gastric tumor vs nontumor tissues. Levels of an lncRNA that we called gastric cancer metastasis associated long noncoding RNA (GMAN) were increased in gastric tumor tissues, compared with nontumor tissues; its up-regulation was associated with tumor metastasis and shorter survival times of patients. The GMAN gene overlaps with the ephrin A1 gene (EFNA1) and was highly expressed in BGC-823 and MKN45 cells. Knockdown of GMAN in these cells did not affect proliferation, colony formation, or adhesion but did reduce their invasive activity in Transwell assays. Ectopic expression of GMAN increased the invasive activity of HGC-27 cells. BGC-823 and MKN45 cells with knockdown of GMAN formed fewer metastases after injection into tail veins of nude mice. Knockdown or knockout of GMAN also reduced levels of ephrin A1 protein in cells. We found that GMAN promoted translation of ephrin A1 messenger RNA into protein by binding to the antisense GMAN RNA (GMAN-AS)-this antisense sequence is also complementary to that of ephrin A1 mRNA. Levels of ephrin A1 protein were also increased in gastric tumors from patients with metastases than in those without metastases. Knockout of ephrin A1 in BGC-823 cells reduced their invasive activity in Transwell assays and ability to form metastases after injection into SCID mice. Ectopic expression of ephrin A1 in BGC-823 cells with knockdown or knockout of GMAN restored their invasive activities and ability form metastases in nude or SCID mice. A CRISPR/Cas9-based strategy to disrupt the GMAN gene significantly reduced the numbers of metastases formed from SGC-7901 cells in mice. CONCLUSIONS: We identified an lncRNA, which we call GMAN, that is increased in gastric tumors from p...

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Inflammatory cytokines, components of cancer stem cells (CSCs) niche, could affect the characteristics of CSCs such as self-renewal and metastasis. Interleukin-17 (IL-17) is a new pro-inflammatory cytokine mainly produced by T-helper (Th17) cells and macrophages. The effects of IL-17 on the characteristics of CSCs remain to be explored. Here we first demonstrated a role of IL-17 in promoting the self-renewal of ovarian CD133(+) cancer stem-like cells (CSLCs). We detected IL-17-producing cells (CD4(+) cells and CD68(+) macrophages) in the niche of CD133(+)CSLCs. Meanwhile, there was IL-17 receptor expression on CD133(+)CSLCs derived from A2780 cell line and primary ovarian cancer tissues. By recombinant human IL-17 stimulation and IL-17 transfection, the growth and sphere formation capacities of ovarian CD133(+)CSLCs were significantly enhanced in a dose-dependent manner. Moreover, ovarian CD133(+)CSLCs transfected with IL-17 showed greater tumorigenesis capacity in nude mice. These data suggest that IL-17 promoted the self-renewal of ovarian CD133(+)CSLCs. Further investigation through gene profiling revealed that the stimulation function of IL-17 on self-renewal of ovarian CD133(+)CSLCs might be mediated by the nuclear factor (NF)-κB and p38 mitogen-activated protein kinases (MAPK) signaling pathway. NF-κB and p38 MAPK were activated by IL-17. More importantly, IL-17-promoted self-renewal was inhibited by specific inhibitors of NF-κB and p38 MAPK. Taken together, our data indicate that IL-17 contributed to ovarian cancer malignancy through promoting the self-renewal of CD133(+)CSLCs and that IL-17 and its signaling pathway might serve as therapeutic targets for the treatment of ovarian cancer.

Heat shock protein 90␣ (Hsp90␣) is a ubiquitously expressed molecular chaperone that is essential for eukaryotic homeostasis. Hsp90␣ can also be secreted extracellularly, where it has been shown to be involved in tumor metastasis. Extracellular Hsp90␣ interacts with and promotes the proteolytic activity of matrix metalloproteinase-2 (MMP-2). However, the regulatory mechanism of Hsp90␣ on MMP-2 activity is still unknown. Here we show that Hsp90␣ stabilizes MMP-2 and protects it from degradation in tumor cells. Further investigation reveals that this stabilization effect is isoform-specific, ATP-independent, and mediated by the interaction between the Hsp90␣ middle domain and the MMP-2 C-terminal hemopexin domain. Moreover, this mechanism also applies to endothelial cells that secrete more Hsp90␣ in their proliferating status. Furthermore, endothelial cell transmigration, Matrigel plug, and tumor angiogenesis assays demonstrate that extracellular Hsp90␣ promotes angiogenesis in an MMP-2-dependent manner. In sum, this study provides new insights into the molecular mechanism of how Hsp90␣ regulates its extracellular client proteins and also reveals for the first time the function of extracellular Hsp90␣ in promoting tumor angiogenesis.Heat shock protein 90 (Hsp90) 2 is an ATP-dependent molecular chaperone that is ubiquitously expressed and essential for cell viability (1). Unlike other types of chaperones, Hsp90 is not required for the biogenesis of most polypeptides but instead functions in the maintenance of the active state of several conformationally labile signaling proteins (2-4). Many of the Hsp90 client proteins are mutated, chimeric, or overexpressed oncogenic proteins (3). Therefore, the chaperoning function of Hsp90 is subverted to a biochemical buffer for genetic lesions in tumor cells, facilitating the malignant transformations of the cells (3). Hsp90 has emerged as a promising target for cancer therapy (5).There are two isoforms of Hsp90 in the cytosol, referred to as Hsp90␣ and Hsp90␤ (6). Intriguingly, the Hsp90␣ isoform also exists extracellularly (7). Recent studies indicate that extracellular Hsp90␣ is significantly correlated with tumor invasiveness and metastasis (8), and the antibody or impermeable inhibitor of Hsp90␣ can suppress tumor metastasis efficiently in mouse models (9 -11). Furthermore, Hsp90␣ can be detected in the blood of cancer patients, and the level of Hsp90␣ is positively associated with tumor malignancy (9). In addition to tumor cells, extracellular Hsp90␣ has also been identified in neuron cells, dermal fibroblasts, keratinocyte, macrophages, and epithelial cells and participates in neuronal cell migration, wound healing, and viral and bacteria infections (7).Accumulating evidence indicates that extracellular Hsp90␣ plays important roles in both physiological and pathological processes, especially in tumor progression (7). However, the molecular mechanism of how extracellular Hsp90␣ functions is still largely unknown (12). Eustace et al. (8) reported that extracellular Hsp90...

The enrichment of Fusobacterium nucleatum (Fn) has been identified in CRC patients and associated with worse outcomes. However, whether Fn was involved in the metastasis of CRC was not well determined. Here, we found that the abundance of Fn was significantly increased in CRC patients with lymph nodes metastasis. To further clarify the role of Fn in CRC metastasis, we performed transwell and wound healing assays after incubating CRC cell lines with or without Fn and injected Fn-treated or untreated CRC cells into nude mice via tail vein. The results indicated that Fn infection promoted CRC cells migration in vitro, as well as lung metastasis in vivo. Interestingly, colonization of Fn was detected in metastatic lung lesions of nude mice by fluorescence in situ hybridization. Mechanistically, RNA sequencing and validation study revealed that Fn significantly upregulated the expression of long non-coding RNA Keratin7-antisense (KRT7-AS) and Keratin7 (KRT7) in CRC cells. Importantly, Fn-induced CRC lung metastasis was attenuated by the depletion of KRT7-AS. In addition, KRT7-AS facilitated CRC cells migration by upregulating KRT7. Subsequently, we found that NF-κB signaling pathway was involved in the upregulation of KRT7-AS upon Fn infection. In conclusion, Fn infection upregulated KRT7-AS/KRT7 by activating NF-κB pathway, which promoted CRC cell migration in vitro and metastasis in vivo.

Purpose: Lymphangiogenesis, the growth of lymphatic vessels, contributes to lymphatic metastasis. However, the precise mechanism underlying lymphangiogenesis remains poorly understood. This study aimed to examine chemokine/chemokine receptors that directly contribute to chemoattraction of activated lymphatic endothelial cells (LEC) and tumor lymphangiogenesis.Experimental Design: We used quantitative RT-PCR to analyze specifically expressed chemokine receptors in activated LECs upon stimulation of vascular endothelial growth factor-C (VEGF-C). Subsequently, we established in vitro and in vivo models to show lymphangiogenic functions of the chemokine axis. Effects of targeting the chemokine axis on tumor lymphangiogenesis and lymphatic metastasis were determined in an orthotopic breast cancer model.Results: VEGF-C specifically upregulates CXCR4 expression on lymphangiogenic endothelial cells. Moreover, hypoxia-inducible factor-1a (HIF-1a) mediates the CXCR4 expression induced by VEGF-C. Subsequent analyses identify the ligand CXCL12 as a chemoattractant for LECs. CXCL12 induces migration, tubule formation of LECs in vitro, and lymphangiogenesis in vivo. CXCL12 also stimulates the phosphorylation of intracellular signaling Akt and Erk, and their specific antagonists impede CXCL12-induced chemotaxis. In addition, its level is correlated with lymphatic vessel density in multiple cancer tissues microarray. Furthermore, the CXCL12-CXCR4 axis is independent of the VEGFR-3 pathway in promoting lymphangiogenesis. Intriguingly, combined treatment with anti-CXCL12 and anti-VEGF-C antibodies results in additive inhibiting effects on tumor lymphangiogenesis and lymphatic metastasis.Conclusions: These results show the role of the CXCL12-CXCR4 axis as a novel chemoattractant for LECs in promoting lymphangiogenesis, and support the potential application of combined targeting of both chemokines and lymphangiogenic factors in inhibiting lymphatic metastasis.