MAFB promotes cancer stemness and tumorigenesis in osteosarcoma through a Sox9-mediated positive feedback loop.
MAFB 通过 Sox9-mediated 正反馈回路促进骨肉瘤的癌症干性和肿瘤发生。
- 作者列表："Chen Y","Wang B","Huang M","Wang T","Hu C","Liu Q","Han D","Chen C","Zhang J","Li Z","Liu C","Lei W","Chang Y","Wu M","Xiang D","Chen Y","Wang R","Huang W","Lei Z","Chu X
:Despite the fact that osteosarcoma is one of the most common primary bone malignancies with poor prognosis, the mechanism behind the pathogenesis of osteosarcoma is only partially known. Here we characterized differentially expressed genes (DEG) by extensive analysis of several publicly available gene expression profile datasets and identified MAFB as a key transcriptional regulator in osteosarcoma progression. MAFB was highly expressed in tumor tissues and required for proliferation and tumorigenicity of osteosarcoma cells. MAFB expression was elevated in osteosarcoma stem cells to maintain their self-renewal potential in vitro and in vivo through upregulation of stem cell regulator Sox9 at the transcriptional level. Sox9 in turn activated MAFB expression via direct recognition of its sequence binding enrichment (SBE) motif on the MAFB locus, thereby forming a positive feedback regulatory loop. Sox9-mediated feedback activation of MAFB was pivotal to tumorsphere-forming and tumor-initiating capacities of osteosarcoma stem cells. Moreover, expression of MAFB and Sox9 was highly correlated in osteosarcoma and associated with disease progression. Combined detection of both MAFB and Sox9 represented a promising prognostic biomarker that stratified a subset of osteosarcoma patients with shortest overall survival. Taken together, these findings reveal a MAFB-Sox9 reciprocal regulatory axis driving cancer stemness and malignancy in osteosarcoma and identify novel molecular targets that might be therapeutically applicable in clinical settings.
尽管骨肉瘤是最常见的原发性骨肿瘤之一，预后较差，但骨肉瘤发病机制仅部分为人所知。在这里，我们通过对几个公开的基因表达谱数据集的广泛分析来表征差异表达基因 (DEG)，并确定 MAFB 是骨肉瘤进展中的关键转录调控因子。MAFB 在肿瘤组织中高表达，是骨肉瘤细胞增殖和致瘤性所必需的。MAFB 在骨肉瘤干细胞中表达升高，通过在转录水平上调干细胞调节因子 Sox9 来维持其在体内外的自我更新潜能。Sox9 反过来通过直接识别 MAFB 位点上的 its 序列结合富集 (SBE) 基序激活 MAFB 表达，从而形成正反馈调控环。MAFB 的 Sox9-mediated 反馈激活对骨肉瘤干细胞的肿瘤球形成和肿瘤启动能力至关重要。此外，MAFB 和 Sox9 在骨肉瘤中的表达高度相关，并与疾病进展相关。联合检测 MAFB 和 Sox9 代表了一个有前途的预后生物标志物，将总体生存期最短的骨肉瘤患者亚群分层。总之，这些发现揭示了骨肉瘤中驱动癌症干细胞和恶性肿瘤的相互调节轴 MAFB-Sox9，并确定了可能在临床治疗上适用的新分子靶点。
METHODS:BACKGROUND:Osteosarcoma is the most common primary bone malignancy in children and adolescents. In order to find factors related to its recurrence, and thus improve recovery prospects, a powerful clinical signature is needed. Long noncoding RNAs (lncRNAs) are essential in osteosarcoma processes and development, and here we report significant lncRNAs to aid in earlier diagnosis of osteosarcoma. METHODS:A univariate Cox proportional hazards regression analysis and a multivariate Cox regression analysis were used to analyze osteosarcoma patients' lncRNA expression data from the Therapeutically Applicable Research To Generate Effective Treatments (TARGET), a public database. RESULTS:A lncRNA signature consisting of three lncRNAs (RP1-261G23.7, RP11-69E11.4 and SATB2-AS1) was selected. The signature was used to sort patients into high-risk and low-risk groups with meaningful recurrence rates (median recurrence time 16.80 vs. >128.22 months, log-rank test, P143.80 months, log-rank test, P=0.006). A multivariate Cox regression analysis showed that the significant lncRNA was an independent prognostic factor for osteosarcoma patients. Functional analysis suggests that these lncRNAs were related to the PI3K-Akt signaling pathway, the Wnt signaling pathway, and the G-protein coupled receptor signaling pathway, all of which have various, important roles in osteosarcoma development. The significant 3-lncRNA set could be a novel prediction biomarker that could aid in treatment and also predict the likelihood of recurrence of osteosarcoma in patients.
METHODS::Long non-coding RNAs (lncRNAs) regulates the initiation and progression of osteosarcoma (OS), specifically lncRNA RP11-361F15.2 has been shown to play prominent roles in tumorigenesis. Previously, M2-Like polarization of tumor-associated macrophages (TAMs) has been identified to play a key role in cancer migration/invasion. Hence, it is essential to understand the role of RP11-361F15.2 in tumorigenesis and its association with M2-Like polarization of TAMs. The results indicate that RP11-361F15.2 is significantly increased in OS tissues, and its expression is positively correlated with cytoplasmic polyadenylation element binding protein 4 (CPEB4) expression and negatively associated with miR-30c-5p expression. Further, overexpression of RP11-361F15.2 increased OS cell migration/invasion and M2-Like polarization of TAMs in vitro, as well as promoted xenograft tumor growth in vivo. Mechanistically, luciferase reporter assays indicated that RP11-361F15.2 upregulated CPEB4 expression by competitively binding to miR-30c-5p. Further, we have identified that RP11-361F15.2 promotes CPEB4-mediated tumorigenesis and M2-Like polarization of TAMs through miR-30c-5p in OS. We also identified that RP11-361F15.2 acts as competitive endogenous RNA (ceRNA) against miR-30c-5p thereby binding and activating CPEB4. This RP11-361F15.2/miR-30c-5p/CPEB4 loop could be used as a potential therapeutic strategy for the treatment of OS.
METHODS:PURPOSE:The objective of this study was to investigate potential correlations between pathologic fractures (PFs) and prognosis of patients with primary central high-grade osteosarcoma of the extremities. METHODS:We retrospectively analyzed 2,847 patients registered in the Consecutive Cooperative Osteosarcoma Study Group database with primary central high-grade osteosarcoma of the extremities, treated between 1980 and 2010. Intended treatment included pre- and postoperative chemotherapy and surgery. Univariable and multivariable survival analyses were performed for all patients and then differentiated for adult and pediatric (≤ 18 years at time of diagnosis) patients. RESULTS:A total of 2,193 patients were ≤ 18 years of age; 11.3% of all patients had PFs. In the overall cohort, presence of PF correlated significantly with tumor site, histologic subtype, relative tumor size, and primary metastases, but not with body mass index or local surgical remission. In univariable analysis, 5-year overall survival (OAS) of patients with and without PF was 63% versus 71%, respectively (P = .007), and 5-year event-free survival (EFS) was 51% versus 58% (P = .026). In pediatric patients, OAS and EFS did not differ significantly between patients with and without PF. In adults, 5-year OAS in patients with and without PF was 46% versus 69% (P < .001), and 5-year EFS was 36% versus 56% (P < .001). In multivariable analysis, PF was not a statistically significant factor for OAS or EFS in the total cohort or in pediatric patients. In adult patients, PF remained an independent prognostic factor for OAS (P = .013; hazard ratio [HR], 1.893). It was not a significant prognostic factor for EFS (P = .263; HR, 1.312). CONCLUSION:In this largest study to date with extremity osteosarcomas, we observed the occurrence of PF to correlate with inferior OAS expectancies in adult but not in pediatric patients.