Osteosarcoma (OS) is a malignant bone sarcoma characterized by a propensity for metastatic spread. Tmem41b is a multi-spanning membrane protein that acts as a novel autophagy-related (ATG) gene; however, its effect on the malignant phenotypes of tumor cells and the corresponding molecular details remains unknown. In the current study, RNA-sequencing, quantitative PCR (qPCR), and immunohistochemical analysis were conducted to prove Tmem41b upregulation in 103 OS tissue specimens and three OS cell lines (U-2OS, U87, and MG63). It was strongly correlated with tumor size (P < 0.01), metastases (P < 0.05), and recurrence (P < 0.05) as well as poor survival time in OS patients. Subsequently, gene set enrichment analysis (GSEA) of U-2OS cells with Tmem41b knockdown links cell receptor activation, proliferation, and invasion according to RNA-sequence, and PCNA, Cyclin D1, Cyclin E1, and MMP13 expression levels were decreased by western blotting assay. Furthermore, the suppressive effect of Tmem41b knockdown on cell proliferation and invasion was demonstrated in vitro and in vivo. Additionally, Tmem41b silencing could significantly inhibit the AKT and p38 signaling pathways. Last, MMP13 upregulation was positively correlated with Tmem41b expression and poor survival time in OS patients via analysis of immunohistochemical detection and bioinformatics. All together, these findings demonstrate the role of Tmem41b and MMP13 as a novel prognostic marker and an attractive therapeutic target for OS.

中文翻译：

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Tmem41b 和 MMP13 的表达与骨肉瘤的不良预后相关。

骨肉瘤（OS）是一种恶性骨肉瘤，其特征是有转移扩散的倾向。Tmem41b 是一种多跨膜蛋白，充当新型自噬相关 (ATG) 基因；然而，它对肿瘤细胞恶性表型的影响以及相应的分子细节仍然未知。在当前的研究中，通过RNA测序、定量PCR（qPCR）和免疫组织化学分析来证明Tmem41b在103个OS组织标本和三个OS细胞系（U-2OS、U87和MG63）中上调。它与肿瘤大小（P < 0.01）、转移（P < 0.05）和复发（P < 0.05）以及 OS 患者的较差生存时间密切相关。随后，对 Tmem41b 敲低的 U-2OS 细胞进行基因集富集分析 (GSEA)，根据 RNA 序列将细胞受体激活、增殖和侵袭联系起来，并且通过蛋白质印迹法，PCNA、Cyclin D1、Cyclin E1 和 MMP13 表达水平降低化验。此外，体外和体内都证明了 Tmem41b 敲低对细胞增殖和侵袭的抑制作用。此外，Tmem41b 沉默可以显着抑制 AKT 和 p38 信号通路。最后，通过免疫组化检测和生物信息学分析，MMP13上调与Tmem41b表达和OS患者较差的生存时间呈正相关。总之，这些发现证明了 Tmem41b 和 MMP13 作为新型预后标志物和有吸引力的 OS 治疗靶点的作用。