Abstract
BackgroundOur previous report demonstrated that genetic ablation of miR-301a reduces Kras-driven lung tumorigenesis in mice. However, the impact of miR-301a on host anti-tumor immunity remains unexplored. Here we assessed the underlying molecular mechanisms of miR-301a in the tumor microenvironment.MethodsThe differentially expressed genes were identified by using deep sequencing. The immune cell counts, and cytokines expression were analyzed by realtime PCR, immunohistochemistry and flow cytometry. The role of miR-301a/Runx3 in lung tumor was evaluated on cell growth, migration and invasion. The function of miR-301a/Runx3 in regulating tumor microenvironment and tumor metastasis were evaluated in Kras transgenic mice and B16/LLC1 syngeneic xenografts tumor models.ResultsIn this work, we identified 1166 up-regulated and 475 down-regulated differentially expressed genes in lung tumor tissues between KrasLA2 and miR-301a−/−; KrasLA2 mice. Immune response and cell cycle were major pathways involved in the protective role of miR-301a deletion in lung tumorigenesis. Overexpression of the miR-301a target, Runx3, was an early event identified in miR-301a−/−; KrasLA2 mice compared to WT-KrasLA2 mice. We found that miR-301a deletion enhanced CD8+ T cell accumulation and IFN-γ production in the tumor microenvironment and mediated antitumor immunity. Further studies revealed that miR-301a deficiency in the tumor microenvironment effectively reduced tumor metastasis by elevating Runx3 and recruiting CD8+ T cells, whereas miR-301a knockdown in tumor cells themselves restrained cell migration by elevating Runx3 expression.ConclusionsOur findings further underscore that miR-301a facilitates tumor microenvironment antitumor immunity by Runx3 suppression in lung tumorigenesis.
Highlights
Our previous report demonstrated that genetic ablation of miR-301a reduces Kras-driven lung tumorigenesis in mice
Transcriptional signature analysis of lung tissues from KrasLA2 and miR-301a−/−;KrasLA2 To investigate the role of miR-301a onset lung tumorigenesis, we performed RNA sequencing using total RNA isolated from lung tissues of KrasLA2 and miR-301a−/−;KrasLA2 mice at age of 9 weeks, when the expression of miR-301a is highest [15]
Ingenuity Pathway Analysis (IPA) revealed the most enriched canonical pathways involved in B cell development, primary immunodeficiency signaling, cell cycle control of chromosomal replication, iCOS-iCOSL signaling in T helper cells, CD28 signaling in T helper cells, and the Th1 pathway (Fig. 1c, Additional file 1: Table S3)
Summary
Our previous report demonstrated that genetic ablation of miR-301a reduces Kras-driven lung tumorigenesis in mice. Of more than 1000 microRNAs identified, miR-301a has been reported to be overexpressed in several tumor types, including lung [8,9,10], colon [11], and pancreatic cancer [12]. Deletion of miR-301a in hematopoietic cells leads to reduced development of colitis-associated colon cancer [15]. In patients with NSCLC, miR-301a is most highly expressed in tumor tissues and is associated with poor differentiation and lymph node metastasis [16]. These in vitro and in vivo data indicate that miR-301a has an important role in the tumor microenvironment and tumor metastasis
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call