The Sp1/FOXC1/HOTTIP/LATS2/YAP/β-catenin cascade promotes malignant and metastatic progression of osteosarcoma.

The prognosis for osteosarcoma (OS) is dismal due to the aggressive tumor growth and high incidence of metastasis. The long noncoding RNA human homeobox A transcript at the distal tip (HOTTIP) and the transcription factor forkhead box C1 (FOXC1) present oncogenic activities in OS. Here, we aimed at gaining insights into the underlying mechanisms and their crosstalk. The expression of FOXC1 and HOTTIP in OS tissues or cell lines was examined by real-time PCR (RT-PCR) and western blot. The in vitro effects of FOXC1 or HOTTIP on cell viability, proliferation, migration, invasion, and expression of target genes were examined using MTT, colony-forming assay, wound-healing, Transwell invasion, and western blot, respectively; the in vivo effects were examined using xenograft and experimental metastasis models. Molecular control of HOTTIP on large tumor suppressor 2 (LATS2) or transactivation of FOXC1 or Sp1 on HOTTIP was assessed by combining RNA immunoprecipitation, qRT-PCR, western blot, ChIP, and luciferase assay. Both FOXC1 and HOTTIP were potently up-regulated in OS tissues and cell lines. FOXC1 and HOTTIP essentially maintained viability, proliferation, migration, and invasion of OS cells in vitro and contributed to xenograft growth or lung metastasis in vivo. Mechanistically, HOTTIP recruited enhancer of zeste homolog 2 (EZH2) and lysine-specific demethylase 1 (LSD1) to silence LATS2 and thus activated YAP/β-catenin signaling. Upstream, Sp1 activated FOXC1 and they both directly transactivated HOTTIP. In summary, we showed that the Sp1/FOXC1/HOTTIP/LATS2/YAP/β-catenin cascade presented oncogenic activities in OS cells. Targeting FOXC1 or HOTTIP may therefore prove beneficial for OS treatment.

Liu K ，Ni JD ，Li WZ ，Pan BQ ，Yang YT ，Xia Q ，Huang J ... -  《-》

Knockdown of HCG18 Inhibits Cell Viability, Migration and Invasion in Pediatric Osteosarcoma by Targeting miR-188-5p/FOXC1 Axis.

Understanding the underlying mechanisms of pediatric osteosarcoma (OS) migration and invasion is important for prognosis and treatment. We tried to measure the expression of long non-coding RNA HLA complex group 18 (HCG18) in OS and reveal its function in the malignant behaviors of OS cells. This study detected the expression of HCG18, miR-188-5p and forkhead box C1 (FOXC1) in OS tissues and cell lines by quantitative real-time PCR (qRT-PCR). The relevance between miR-188-5p and HCG18 or FOXC1 was affirmed by dual-luciferase reporter (DLR) assay. Cell viability was analyzed by MTT assay. Transwell assay was utilized to test cell invasion and migration. FOXC1 protein expression was detected by western blot. HCG18 expression was elevated in OS tissues, and enhanced HCG18 expression was related to metastasis. HCG18 silencing repressed the viability, migration and invasion of OS cells. Moreover, HCG18 interacted with miR-188-5p. MiR-188-5p up-regulation repressed cell viability, invasion and migration in OS cells. FOXC1, a known target of miR-188-5p, was negatively modulated by miR-188-5p. Furthermore, miR-188-5p inhibition or FOXC1 over-expression partially abolished the reduced of cell viability, invasion and migration mediated by HCG18 silencing in OS cell lines. This study revealed that HCG18 knockdown repressed the viability, invasion and migration of OS cells by targeting miR-188-5p and regulating FOXC1 expression. Thus, HCG18/ miR-188-5p/FOX may be a hopeful target for OS therapy.

Zhao Z ，Chen J ，Xia D 《-》

Long non-coding RNA XIST promotes osteosarcoma progression by targeting YAP via miR-195-5p.

The lncRNA XIST (X inactive-specific transcript) is an oncogenic lncRNA that is present in various malignant tumors; however, its role and molecular mechanisms in osteosarcoma (OS) progression remain unclear. In the current study, 40 pairs of OS tissues and matched adjacent non-tumor tissues were collected. qRT-PCR was conducted to investigate the differences in XIST expression in tissues and OS cell lines. The proliferation, invasion, and EMT status of OS cells after transfection were assessed with WST-1 assays, Transwell assays, and Western blot analysis, respectively. Whether miR-195-5p was a direct downstream target of XIST was verified by both bioinformatics target gene prediction and dual-luciferase report analysis. A mouse model was established to evaluate tumor proliferation in vivo. Our results demonstrated that XIST expression was significantly upregulated in OS tissues and cell lines and negatively correlated with clinical prognosis. XIST knockdown inhibited cancer cell proliferation and invasion in vitro, inhibited the EMT of OS cells in vitro, and suppressed subcutaneous tumor growth in vivo. Further analysis demonstrated that XIST regulated YAP expression by functioning as a competing endogenous RNA that sponged miR-195-5p in OS cells. XIST directly interacted with miR-195-5p and decreased the binding of miR-195-5p to the YAP 3'UTR, which suppressed the degradation of YAP mRNA by miR-195-5p. In conclusion, this work demonstrates that lncRNA XIST enhances OS cancer cell proliferation and invasion in part through the miR-195-5p/YAP pathway. Therefore, lncRNA XIST might be a promising therapeutic target for OS.

Yang C ，Wu K ，Wang S ，Wei G ... -  《-》

LncRNA HOTTIP facilitates cell proliferation, invasion, and migration in osteosarcoma by interaction with PTBP1 to promote KHSRP level.

Yao XY ，Liu JF ，Luo Y ，Xu XZ ，Bu J ... -  《-》

Long non-coding RNA SNGH7 Is activated by SP1 and exerts oncogenic properties by interacting with EZH2 in ovarian cancer.

Long non-coding RNAs (lncRNAs) are key regulators or a range of diseases and chronic conditions such as cancers, but how they function in the context of ovarian cancer (OC) is poorly understood. The Coding-Potential Assessment Tool was used to assess the likely protein-coding potential of SNHG7. SNHG7 expression was elevated in ovarian tumour tissues measured by qRT-PCR. The online database JASPAR was used to predict the transcription factors binding to SNHG7. Twenty-four-well Transwell plates were used for invasion assays. RNA immunoprecipitation was performed to determine RNA-protein associations. EdU assay was introduced to detect cell proliferation. Chromatin immunoprecipitation was performed to confirm the directly interaction between DNA and protein. We discovered that in the context of OC there is a significant up-regulation of the lncRNA SNHG7. Knocking down this lncRNA disrupted both OC cell invasion and proliferation, while its overexpression had the opposite effect. SP1 binding sites were present in the SNHG7 promoter, and chromatin immunoprecipitation (ChIP) confirmed direct SP1 binding to this region, activating SNHG7 transcription. We found that at a mechanistic level in OC cells, KLF2 is a probable SNHG7 target, as we found that SHNCCC16 directly interacts with EZH2 and thus represses KLF2 expression. In summary, this research demonstrates that lncRNA SNHG7 is an SP1-activated molecule that contributes to OC progression by providing a scaffold whereby EZH2 can repress KLF2 expression.

Bai Z ，Wu Y ，Bai S ，Yan Y ，Kang H ，Ma W ，Zhang J ，Gao Y ，Hui B ，Ma H ，Li R ，Zhang X ，Ren J ... -  《-》