G9a is a mammalian histone methyltransferase that contributes to the epigenetic silencing of tumor suppressor genes. Emerging evidence suggests that G9a is required to maintain the malignant ...phenotype, but the role of G9a function in mediating tumor metastasis has not been explored. Here, we show that G9a is expressed in aggressive lung cancer cells, and its elevated expression correlates with poor prognosis. RNAi-mediated knockdown of G9a in highly invasive lung cancer cells inhibited cell migration and invasion in vitro and metastasis in vivo. Conversely, ectopic G9a expression in weakly invasive lung cancer cells increased motility and metastasis. Mechanistic investigations suggested that repression of the cell adhesion molecule Ep-CAM mediated the effects of G9a. First, RNAi-mediated knockdown of Ep-CAM partially relieved metastasis suppression imposed by G9a suppression. Second, an inverse correlation between G9a and Ep-CAM expression existed in primary lung cancer. Third, Ep-CAM repression was associated with promoter methylation and an enrichment for dimethylated histone H3K9. G9a knockdown reduced the levels of H3K9 dimethylation and decreased the recruitment of the transcriptional cofactors HP1, DNMT1, and HDAC1 to the Ep-CAM promoter. Our findings establish a functional contribution of G9a overexpression with concomitant dysregulation of epigenetic pathways in lung cancer progression.
DNA N6-methyldeoxyadenosine (6mA) is rarely present in mammalian cells and its nuclear role remains elusive.
Here we show that hypoxia induces nuclear 6mA modification through a DNA ...methyltransferase, METTL4, in hypoxia-induced epithelial-mesenchymal transition (EMT) and tumor metastasis. Co-expression of METTL4 and 6mA represents a prognosis marker for upper tract urothelial cancer patients. By RNA sequencing and 6mA chromatin immunoprecipitation-exonuclease digestion followed by sequencing, we identify lncRNA RP11-390F4.3 and one novel HIF-1α co-activator, ZMIZ1, that are co-regulated by hypoxia and METTL4. Other genes involved in hypoxia-mediated phenotypes are also regulated by 6mA modification. Quantitative chromatin isolation by RNA purification assay shows the occupancy of lncRNA RP11-390F4.3 on the promoters of multiple EMT regulators, indicating lncRNA-chromatin interaction. Knockdown of lncRNA RP11-390F4.3 abolishes METTL4-mediated tumor metastasis. We demonstrate that ZMIZ1 is an essential co-activator of HIF-1α.
We show that hypoxia results in enriched 6mA levels in mammalian tumor cells through METTL4. This METTL4-mediated nuclear 6mA deposition induces tumor metastasis through activating multiple metastasis-inducing genes. METTL4 is characterized as a potential therapeutic target in hypoxic tumors.
Purpose
Metastasis is the end stage of renal cell carcinoma (RCC), and clear cell renal cell carcinoma (ccRCC) is the most common malignant subtype. The hypoxic microenvironment is a common feature ...in ccRCC and plays an essential role in the regulation of epithelial–mesenchymal transition (EMT). Accumulating evidence manifests that long non‐coding RNAs (lncRNAs) participate in RCC tumorigenesis and regulate hypoxia‐induced EMT. Here, we identified a lncRNA RP11‐367G18.1 induced by hypoxia, that was overexpressed in ccRCC tissues.
Methods
A total of 216 specimens, including 149 ccRCC tumor samples and 67 related normal kidney parenchyma tissue samples, were collected. To investigate the biological fucntions of RP11.367G18.1 in ccRCC, migration, invasion, soft agar colony formation, xenograft tumorigenicity assays, and tail vein and orthotopic metastatic mouse models were performed. The relationship between RP11‐367G18.1 and downstream signaling was analyzed utilizing reporter assay, RNA pull‐down, chromatin immunopreciptation, and chromatin isolation by RNA purification assays.
Results
Hypoxic conditions and overexpression of HIF‐1α increased the level of RP11‐367G18.1. RP11‐367G18.1 induced EMT and enhanced cell migration and invasion through variant 2. Inhibition of RP11‐367G18.1 variant 2 reversed hypoxia‐induced EMT phenotypes. An in vivo study revealed that RP11‐367G18.1 variant 2 was required for hypoxia‐induced tumor growth and metastasis in ccRCC. Mechanistically, RP11‐367G18.1 variant 2 interacted with p300 histone acetyltransferase to regulate lysine 16 acetylation on histone 4 (H4K16Ac), thus contributing to hypoxia‐regulated gene expression. Clinically, RP11‐367G18.1 variant 2 was upregulated in ccRCC tissues, particularly metastatic ccRCC tissues, and it is linked to poor overall survival.
Conclusion
These findings demonstrate the prognostic value and EMT‐promoting role of RP11‐367G18.1 and indicate that this lncRNA may provide a therapeutic target for ccRCC.
Hypoxia upregulated lncRNA RP11‐367G18.1 variant 2 which was associated with p300‐mediated chromatin modifying complex to activate H4K16Ac marks. RP11‐367G18.1 variant 2 increased the levels of H4K16Ac on the promoter of hypoxia‐regulated genes leading to EMT and tumor metastasis.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Classic signaling by the proinflammatory cytokine interleukin 6 (IL-6) involves its binding to target cells that express the membrane-bound IL-6 receptor α. However, an alternate signaling pathway ...exists in which soluble IL-6 receptor (sIL-6Rα) can bind IL-6 and activate target cells that lack mIL-6Rα, such as endothelial cells. This alternate pathway, also termed trans-signaling, serves as the major IL-6 signaling pathway in various pathologic proinflammatory conditions including cancer. Here we report that sIL-6Rα is elevated in malignant ascites from ovarian cancer patients, where it is associated with poor prognosis. IL-6 trans-signaling on endothelial cells prevented chemotherapy-induced apoptosis, induced endothelial hyperpermeability, and increased transendothelial migration of ovarian cancer cells. Selective blockade of the MAPK pathway with ERK inhibitor PD98059 reduced IL-6/sIL-6Rα-mediated endothelial hyperpermeability. ERK activation by the IL-6/sIL-6Rα complex increased endothelial integrity via Src kinase activation and Y685 phosphorylation of VE-cadherin. Selective targeting of IL-6 trans-signaling in vivo reduced ascites formation and enhanced the taxane sensitivity of intraperitoneal human ovarian tumor xenografts in mice. Collectively, our results show that increased levels of sIL-6Rα found in ovarian cancer ascites drive IL-6 trans-signaling on endothelial cells, thereby contributing to cancer progression. Selective blockade of IL-6 trans-signaling may offer a promising therapeutic strategy to improve the management of patients with advanced ovarian cancer.
Abstract
Carbonic anhydrase IX (CA9) expression level has been considered as a poor prognostic factor in hepatocellular carcinoma (HCC) patients. However, the judging criteria of CA9 level is hard to ...define for potential clinical applications. Unlike CA9 expression level, CA9 polymorphism is poorly documented in HCC. Here, we found that people carry A allele at CA9 rs1048638, a 3′UTR SNP, has higher risk of HCC. rs1048638-CA correlates with advanced stages, larger tumor sizes, more vascular invasion, and shorter survival of HCC patients. A allele at CA9 rs1048638 impairs miR-34a, a tumor suppressor miRNA in HCC, binding to CA9 3′UTR and desensitizes CA9 mRNA to miR-34a-dependent RNA degradation. CA9 expression levels were also correlated with miR-34a levels and rs1048638 genotypes in HCC patients. rs1048638 influences HCC risk and progression through effects on miR-34a-targeted CA9 expression in HCC. In conclusion, genetic variations of the CA9 3′UTR play important roles in regulating CA9 expression and cancer progression, which is a novel determinant and target for HCC metastasis and prognosis.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Hepatitis promotes the development and recurrence of hepatocellular carcinoma (HCC). Receptor tyrosine kinases (RTK) play critical roles in the development of many cancers. We explored the potential ...roles of RTKs in hepatitis-related liver cancers.
We conducted loss-of-function screening to elucidate the roles of RTKs in the development of HCC
and
.
Many RTKs were coexpressed in HCC and were involved in tumor development and growth. Of these, TYRO3 promoted tumor growth and was clinically associated with hepatitis activity and poor prognosis. In mice, chemical-induced hepatitis transcriptionally activated Tyro3 expression via IL-6/IL6R-STAT3 signaling. Moreover, hepatitis-associated apoptotic cells facilitated the presentation of GAS6, a TYRO3 ligand, to further activate TYRO3-mediated signaling. Furthermore, TYRO3 activation elicited intracellular SRC- and STAT3 signaling. In mice, hepatitis and Tyro3 synergistically promoted HCC development. Silencing TYRO3 expression or inhibiting its kinase activity suppressed xenograft HCC growth in nude mice.
Many RTKs are simultaneously involved in HCC development. Hepatitis exerts dual effects on the activation of TYRO3-mediated signaling in HCC cells, which further elicits the "TYRO3-STAT3-TYRO3" signaling loop to facilitate tumor growth. Our findings unveil a previously unrecognized link between RTKs and hepatitis-associated HCC and suggest TYRO3 as a marker and therapeutic target for the HCCs with higher hepatitis activity.
Clear cell renal cell carcinoma (ccRCC) is the main type of RCC, which is the most common type of malignant kidney tumor in adults. A subpopulation (>30%) of ccRCC patients develop metastasis; ...however, the molecular mechanism remains largely unknown. Here, we found that LTF, the gene encoding lactotransferrin, is dramatically downregulated in primary tumors compared to normal tissues derived from ccRCC patients deposited in The Cancer Genome Atlas (TCGA) database and is a favorable prognostic marker. Moreover, LTF downregulation appears to be more dominant in metastatic ccRCC. LTF overexpression suppresses migration ability in A498 ccRCC cells with high metastatic potential, whereas LTF knockdown fosters cellular migration in poorly metastatic ccRCC cells. Gene set enrichment analysis demonstrated that LTF expression inversely correlates with the progression of epithelial-mesenchymal transition (EMT) in ccRCC, which was further confirmed by RT-PCR experiments. Therapeutically, the administration of recombinant LTF protein significantly suppresses the cell migration ability and lung metastatic potential of ACHN cells, as well as LTF-silenced A498 cells. The gene knockdown of lipoprotein receptor-related protein 1 (LRP1) robustly blocked recombinant LTF protein-induced inhibition of cellular migration and gene expression of EMT markers in ACHN cells. LTF downregulation and LRP1 upregulation combined predicted a poor overall survival rate in ccRCC patients compared to that with either factor alone. Our findings uncover a new mechanism by which LTF may interact with LRP1 to inhibit metastatic progression in ccRCC and also reveal the therapeutic value of recombinant LTF protein in treating metastatic ccRCC.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Abstract
Background
The hypoxia-responsive long non-coding RNA,
RP11-367G18.1
, has recently been reported to induce histone 4 lysine 16 acetylation (H4K16Ac) through its variant 2; however, the ...underlying molecular mechanism remains poorly understood.
Methods
RNA pull-down assay and liquid chromatography-tandem mass spectrometry were performed to identify
RP11-367G18.1
variant 2-binding partner. The molecular events were examined utilizing western blot analysis, real-time PCR, luciferase reporter assay, chromatin immunoprecipitation, and chromatin isolation by RNA purification assays. The migration, invasion, soft agar colony formation, and in vivo xenograft experiments were conducted to evaluate the impact of
RP11-367G18.1
variant 2–YY1 complex on tumor progression.
Results
In this study, RNA sequencing data revealed that hypoxia and
RP11-367G18.1
variant 2 co-regulated genes were enriched in tumor-related pathways. YY1 was identified as an
RP11-367G18.1
variant 2-binding partner that activates the H4K16Ac mark. YY1 was upregulated under hypoxic conditions and served as a target gene for hypoxia-inducible factor-1α.
RP11-367G18.1
variant 2 colocalized with YY1 and H4K16Ac in the nucleus under hypoxic conditions. Head and neck cancer tissues had higher levels of
RP11-367G18.1
and YY1 which were associated with poor patient outcomes.
RP11-367G18.1
variant 2–YY1 complex contributes to hypoxia-induced epithelial–mesenchymal transition, cell migration, invasion, and tumorigenicity. YY1 regulated hypoxia-induced genes dependent on
RP11-367G18.1
variant 2.
Conclusions
RP11-367G18.1
variant 2–YY1 complex mediates the tumor-promoting effects of hypoxia, suggesting that this complex can be targeted as a novel therapeutic strategy for cancer treatment.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The molecular mechanism underlying clear cell renal cell carcinoma (ccRCC) metastasis remains unclear. We therefore aimed to elucidate the role of IMPA2 in ccRCC metastatic progression.
Using the ...Cancer Genome Atlas (TCGA) database and immunohistochemistry (IHC) staining, we investigated differences in IMPA2 mRNA and protein expression, as well as their clinical relevance, in ccRCC. To investigate the function of IMPA2 in ccRCC metastasis, we performed in vitro migration and in vivo lung colony-forming assays. We further explored the effect of microRNA (miR)-25 on IMPA2 expression by performing a luciferase reporter assay.
We show that ccRCC expresses relatively lower transcript levels of IMPA2 than normal kidney tissue. IMPA2 downregulation was greater in high-grade ccRCC than in low-grade ccRCC and was correlated with a poor prognosis in ccRCC patients. Importantly, we demonstrate that IMPA2 expression is inversely associated with the metastatic potential of ccRCC cells. We found that IMPA2 knockdown promotes, but overexpression suppresses, the cellular migration and lung colony-forming abilities of ccRCC cells. By using in silico and luciferase reporter assays, we found that IMPA2 expression is primarily influenced by miR-25 in ccRCC cells. Significantly, the inhibition of miR-25 function restored IMPA2 expression, thereby diminishing the metastatic potential of ccRCC cells.
We conclude that miR-25-mediated IMPA2 downregulation constitutes a novel signature for cancer metastasis and poor outcomes in ccRCC. We further postulate that the therapeutic targeting of miR-25 can be useful for preventing the metastatic progression of ccRCC associated with IMPA2 downregulation.
This study was supported by the Ministry of Science and Technology, Taiwan (MOST 107-2314-B-038-094, MOST 106-2314-B-038-069-MY3, MOST 105-2320-B-038-021-MY3 and MOST 107-2320-B-038-056).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
G-protein-coupled receptor kinase interacting protein 1 (GIT1) is participated in cell movement activation, which is a fundamental process during tissue development and cancer progression. GIT1/PIX ...forming a functional protein complex that contributes to Rac1/Cdc42 activation, resulting in increasing cell mobility. Although the importance of Rac1/Cdc42 activation is well documented in cancer aggressiveness, the clinical importance of GIT1 remains largely unknown. Here, we investigated the clinical significance of GIT1 expression in non-small-cell lung cancer (NSCLC) and also verified the importance of GIT1-Rac1/Cdc42 axis in stimulating NSCLC cell mobility. The result indicated higher GIT1 expression patients had significantly poorer prognoses in disease-free survival (DFS) and overall survival (OS) compared with lower GIT1 expression patients. Higher GIT1 expression was an independent prognostic factor by multivariate analysis and associated with migration/invasion of NSCLC cells in transwell assay. In vivo studies indicated that GIT1 promotes metastasis of NSCLC cells. Finally, GIT1 was found to stimulate migration/invasion by altering the activity of Rac1/Cdc42 in NSCLC cells. Together, the GIT1 expression is associated with poor prognosis in patients with NSCLC. GIT1 is critical for the invasiveness of NSCLC cells through stimulating the activity of Rac1/Cdc42.
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