Bone metastasis is associated with cancer‐related death in patients with prostate cancer (PCa). Long noncoding RNAs (lncRNAs) play critical roles in tumor progression of PCa. Nevertheless, the biological function of lncRNAs in PCa bone metastasis remains unclear. PCAT7 was identified as a bone metastasis‐related lncRNA via analyzing TCGA dataset. Meanwhile, PCAT7 was found to be elevated in primary PCa tissues with bone metastasis and associated with bone metastasis status and poor prognosis of patients with PCa. Functionally, our results reveal that PCAT7 overexpression promotes PCa bone metastasis in vivo, as well as migration, invasion, and EMT of PCa cells in vitro; on the contrary, PCAT7 knockdown has an inverse effect. Mechanistically, PCAT7 activates TGF‐β/SMAD signaling by upregulating TGFBR1 expression via sponging miR‐324‐5p. In turn, TGF‐β signaling forms a positive feedback loop with PCAT7 via SMAD3/SP1 complex‐induced PCAT7 upregulation. Finally, the clinical positive correlation between PCAT7 and TGFBR1 and TGF‐β signaling activity, and the negative association with miR‐324‐5p are further demonstrated in PCa tissues and clinical primary PCa cells. This study reveals a novel mechanism that is responsible for the constitutive activation of TGF‐β signaling in PCa bone metastasis, implying that PCAT7 can act as a potential therapeutic target against bone metastasis of PCa via disrupting the constitutive active loop between PCAT7 and TGF‐β signaling.

Background Bone metastasis is the leading cause of tumor‐related death in prostate cancer (PCa) patients. Long noncoding RNAs (lncRNAs) have been well documented to be involved in the progression of multiple cancers. Nevertheless, the role of lncRNAs in PCa bone metastasis remains largely unclear. Methods The expression of prostate cancer‐associated transcripts was analyzed in published datasets and further verified in clinical samples and cell lines by RT‐qPCR and in situ hybridization assays. Colony formation assay, MTT assay, cell cycle analysis, EdU assay, Transwell migration and invasion assays, wound healing assay, and in vivo experiments were carried out to investigate the function of prostate cancer‐associated transcript 6 ( PCAT6 ) in bone metastasis and tumor growth of PCa. Bioinformatic analysis, RNA pull‐down, and RIP assays were conducted to identify the proteins binding to PCAT6 and the potential targets of PCAT6 . The therapeutic potential of targeting PCAT6 by antisense oligonucleotides (ASO) was further explored in vivo . Results PCAT6 was upregulated in PCa tissues with bone metastasis and increased PCAT6 expression predicted poor prognosis in PCa patients. Functional experiments found that PCAT6 knockdown significantly inhibited PCa cell invasion, migration, and proliferation in vitro , as well as bone metastasis and tumor growth in vivo . Mechanistically, METTL3 ‐mediated m 6 A modification contributed to PCAT6 upregulation in an IGF2BP2 ‐dependent manner. Furthermore, PCAT6 upregulated IGF1R expression by enhancing IGF1R mRNA stability through the PCAT6 / IGF2BP2 / IGF1R RNA‐protein three‐dimensional complex. Importantly, PCAT6 inhibition by ASO in vivo showed therapeutic potential against bone metastasis in PCa. Finally, the clinical correlation of METTL3 , IGF2BP2 , IGF1R , and PCAT6 was further demonstrated in PCa tissues and cells. Conclusions Our study uncovers a novel molecular mechanism by which the m 6 A‐induced PCAT6 / IGF2BP2 / IGF1R axis promotes PCa bone metastasis and tumor growth, suggesting th...

Background Clinically, prostate cancer (PCa) exhibits a high avidity to metastasize to bone. Myc-associated zinc-finger protein (MAZ) is a well-documented oncogene involved in the progression and metastasis of multiple cancer types, even in PCa. However, the clinical significance and biological roles of MAZ in bone metastasis of PCa remain unclear. Methods MAZ expression was examined in PCa tissues with bone metastasis, PCa tissues without bone metastasis and metastatic bone tissues by real-time PCR and immunohistochemistry (IHC), respectively. Statistical analysis was performed to evaluate the clinical correlation between MAZ expression and clinicopathological features and bone metastasis-free survival in PCa patients. Biological roles of MAZ in bone metastasis of PCa were investigated both in vitro by transwell assay, and in vivo by a mouse model of left cardiac ventricle inoculation. The bioinformatics analysis, western blot, pull-down assays, chromatin immunoprecipitation (ChIP) and luciferase reporter assays were applied to demonstrate and examine the relationship between MAZ and its potential downstream signalling pathway. TaqMan copy number assay was performed to identify the underlying mechanism responsible for MAZ overexpression in PCa tissues. Results MAZ expression is elevated in PCa tissues with bone metastasis compared with that in PCa tissues without bone metastasis, and is further increased in metastatic bone tissues. High expression of MAZ positively correlates with poor overall and bone metastasis-free survival in PCa patients. Upregulating MAZ elevates, while silencing MAZ represses the invasion and migration abilities of PCa cells in vitro and bone metastasis ability in vivo. Our results further reveal that MAZ promotes bone metastasis of PCa dependent on KRas signalling, although MAZ transcriptionally upregulates KRas and HRas expression, where the Ral guanine nucleotide exchange factor (RalGEF) signaling is responsible for the different roles of KRas and HRas in mediating the pro-bone metastasis of MAZ in PCa. Finally, our results indicate that recurrent gains contribute to MAZ overexpression in a small portion of PCa tissues. Conclusion These results indicate that the MAZ/Kras/ RalGEF signalling axis plays a crucial role in promoting PCa cell bone metastasis, suggesting a potential therapeutic utility of MAZ in bone metastasis of PCa. Electronic supplementary material The online version of this article (10.1186/s13046-019-1374-x) contains supplementary material, which is available to authorized users.

Background: The reciprocal repressive loop between ZEB1 and miRNAs has been extensively reported to play an important role in tumor progression and metastasis of various human tumor types. The aim of this study was to elucidate the role and the underlying mechanism of the double-negative feedback loop between ZEB1and miR-33a-5p in bone metastasis of prostate cancer (PCa).Methods: miR-33a-5p expression was examined in 40 bone metastatic and 165 non-bone metastatic PCa tissues by real-time PCR. Statistical analysis was performed to evaluate the clinical correlation between miR-33a-5p expression and clinicopathological characteristics, and overall and bone metastasis-free survival in PCa patients. The biological roles of miR-33a-5p in bone metastasis of PCa were investigated both by EMT and the Transwell assay in vitro, and by a mouse model of left cardiac ventricle inoculation in vivo. siRNA library, real-time PCR and chromatin immunoprecipitation (ChIP) were used to identify the underlying mechanism responsible for the decreased expression of miR-33a-5p in PCa. Bioinformatics analysis, Western blotting and luciferase reporter analysis were employed to examine the relationship between miR-33a-5p and its potential targets. Clinical correlation of miR-33a-5p with its targets was examined in human PCa tissues and primary PCa cells.Results: miR-33a-5p expression was downregulated in PCa tissues with bone metastasis and bone-derived cells, and low expression of miR-33a-5p strongly and positively correlated with advanced clinicopathological characteristics, and shorter overall and bone metastasis-free survival in PCa patients. Upregulating miR-33a-5p inhibited, while silencing miR-33a-5p promoted EMT, invasion and migration of PCa cells. Importantly, upregulating miR-33a-5p significantly repressed bone metastasis of PC-3 cells in vivo. Our results further revealed that recurrent ZEB1 upregulation induced by copy number gains transcriptionally inhibited miR-33a-5p expression, contributing to the reduced expression of miR-33a-5p in bone metastatic PCa tissues. In turn, miR-33a-5p formed a double negative feedback loop with ZEB1 in target-independent manner, which was dependent on TGF-β signaling. Finally, the clinical negative correlations of miR-33a-5p with ZEB1 expression and TGF-β signaling activity were demonstrated in PCa tissues and primary PCa cells.Conclusion: Our findings elucidated that copy number gains of ZEB1-triggered a TGF-β signaling-dependent miR-33a-5p-mediated negative feedback loop was highly relevant to the bone metastasis of PCa.

Background Epidermal growth factor receptor (EGFR) is both a driver oncogene and a therapeutic target in advanced head and neck squamous cell carcinoma (HNSCC). However, response to EGFR treatment is inconsistent and lacks markers for treatment prediction. This study investigated EGFR-induced epithelial-to-mesenchymal transition (EMT) as a central parameter in tumor progression and identified novel prognostic and therapeutic targets, and a candidate predictive marker for EGFR therapy response. Methods Transcriptomic profiles were analyzed by RNA sequencing (RNA-seq) following EGFR-mediated EMT in responsive human HNSCC cell lines. Exclusive genes were extracted via differentially expressed genes (DEGs) and a risk score was determined through forward feature selection and Cox regression models in HNSCC cohorts. Functional characterization of selected prognostic genes was conducted in 2D and 3D cellular models, and findings were validated by immunohistochemistry in primary HNSCC. Results An EGFR-mediated EMT gene signature composed of n = 171 genes was identified in responsive cell lines and transferred to the TCGA-HNSCC cohort. A 5-gene risk score comprising DDIT4, FADD, ITGB4, NCEH1, and TIMP1 prognosticated overall survival (OS) in TCGA and was confirmed in independent HNSCC cohorts. The EGFR-mediated EMT signature was distinct from EMT hallmark and partial EMT (pEMT) meta-programs with a differing enrichment pattern in single malignant cells. Molecular characterization showed that ITGB4 was upregulated in primary tumors and metastases compared to normal mucosa and correlated with EGFR/MAPK activity in tumor bulk and single malignant cells. Preferential localization of ITGB4 together with its ligand laminin 5 at tumor-stroma interfaces correlated with increased tumor budding in primary HNSCC tissue sections. In vitro, ITGB4 knock-down reduced EGFR-mediated migration and invasion and ITGB4-antagonizing antibody ASC8 impaired 2D and 3D invasion. Furthermore, a logistic regression model defined ITGB4 as a predictive marker of progression-free survival in response to Cetuximab in recurrent metastatic HNSCC patients. Conclusions EGFR-mediated EMT conveyed through MAPK activation contributes to HNSCC progression upon induction of migration and invasion. A 5-gene risk score based on a novel EGFR-mediated EMT signature prognosticated survival of HNSCC patients and determined ITGB4 as potential therapeutic and predictive target in patients with strong EGFR-mediated EMT.

Dysfunction of the intestinal epithelial barrier plays an important role in the pathogenesis of several intestinal diseases, including celiac disease, inflammatory bowel disease, and irritable bowel syndrome.

Ulceration and immune status are independent prognostic factors for survival in melanoma patients. Herein univariate Cox regression analysis revealed 53 ulcer-immunity-related DEGs. We performed consensus clustering to divide The Cancer Genome Atlas (TCGA) cohort (n = 467) into three subtypes with different prognosis and biological functions, followed by validation in three merged Gene Expression Omnibus (GEO) cohorts (n = 399). Multiomics approach was used to assess differences among the subtypes. Cluster 3 showed relatively lesser amplification and expression of immune checkpoint genes. Moreover, Cluster 3 lacked immune-related pathways and immune cell infiltration, and had higher proportion of non-responders to immunotherapy. We also constructed a prognostic model based on ulceration and immune related genes in melanoma. EIF3B was a hub gene in the intersection between genes specific to Cluster 3 and those pivotal for melanoma growth (DepMap, https://depmap.org/portal/download/). High EIF3B expression in TCGA and GEO datasets was related to worst prognosis. In vitro models revealed that EIF3B knockdown inhibited melanoma cell migration and invasion, and decreased TGF-β1 level in supernatant compared with si-NC cells. EIF3B expression was negatively correlated with immune-related signaling pathways, immune cell gene signatures, and immune checkpoint gene expression. Moreover, its low expression could predict partial response to anti-PD-1 immunotherapy. To summarize, we established a prognostic model for melanoma and identified the role of EIF3B in melanoma progression and immunotherapy resistance development.

Primary tumors are widely associated with an excess in body fat. The role of adipose tissue on tumor cell homing to bone is yet poorly defined. In this study, we aimed to assess whether bone colonization by tumor cells is favored by an adipocyte-rich bone marrow. We delineated the accompanying alterations of the bone microenvironment and established a treatment approach that interferes with high fat diet (HFD)-induced bone metastasis formation. We were able to show that adipocytes affect skeletal tumor growth in a metastatic model of breast cancer in male rats and melanoma in male mice as well as in human breast cancer bone biopsies. Indeed, HFD-induced bone marrow adiposity was accompanied by accelerated tumor progression and increased osteolytic lesions. In human bone metastases, bone marrow adiposity correlated with tumor cell proliferation. By antagonization of the adipocyte differentiation and storage pathway linked to the peroxisome proliferator-activated receptor gamma (PPARγ) with bisphenol-A-diglycidylether (BADGE), we were able to decelerate tumor progression and subsequent osteolytic damage in the bones of two distinct metastatic animal models exposed to HFD. Overall these data show that adipose tissue is a critical factor in bone metastases and cancer-induced bone loss.