Identification of mitochondrial RNA polymerase as a potential therapeutic target of osteosarcoma.

POLRMT (RNA polymerase mitochondrial) is essential for transcription of mitochondrial genome encoding components of oxidative phosphorylation process. The current study tested POLRMT expression and its potential function in osteosarcoma (OS). The Cancer Genome Atlas (TCGA) cohorts and Gene Expression Profiling Interactive Analysis (GEPIA) database both show that POLRMT transcripts are elevated in OS tissues. In addition, POLRMT mRNA and protein levels were upregulated in local OS tissues as well as in established and primary human OS cells. In different OS cells, shRNA-induced stable knockdown of POLRMT decreased cell viability, proliferation, migration, and invasion, whiling inducing apoptosis activation. CRISPR/Cas9-induced POLRMT knockout induced potent anti-OS cell activity as well. Conversely, in primary OS cells ectopic POLRMT overexpression accelerated cell proliferation and migration. In vivo, intratumoral injection of adeno-associated virus-packed POLRMT shRNA potently inhibited U2OS xenograft growth in nude mice. Importantly, levels of mitochondrial DNA, mitochondrial transcripts and expression of respiratory chain complex subunits were significantly decreased in U2OS xenografts with POLRMT shRNA virus injection. Together, POLRMT is overexpressed in human OS, promoting cell growth in vitro and in vivo. POLRMT could be a novel therapeutic target for OS.

CXCL13 inhibits microRNA-23a through PI3K/AKT signaling pathway in adipose tissue derived-mesenchymal stem cells.

OBJECTIVES: Adipose tissue derived-mesenchymal stem cells (AMSCs) are one of the most widely used MSCs in the cell therapy for regenerative medicine. In the current study, the role of CXCL13 in AMSCs and its potential signaling pathway were investigated. METHODS: AMSCs were isolated from adipose tissue of healthy subjects. After administrating the cells with CXCL13, the expression levels of miR-23a and runt-related transcription factor 2 (Runx2) were assessed by real-time PCR and western blot. The alterations of phosphoinositide-3 kinase (PI3K)/Akt, stress-activated protein kinase (SAPK)/c-jun kinase (JNK), and extracellular-signal-regulated kinase (ERK1/2) pathways were also evaluated. RESULTS: CXCL13 down-regulated miR-23a and up-regulated Runx2 expression in AMSCs. The inhibitor specific for PI3K/AKT, but not SAPK/JNK and ERK ERK1/2, reversed the effects of CXCL13 on miR-23a and Runx2 expression. CONCLUSION: CXCL13 inhibits miR-23a expression through modulating PI3K/AKT pathway in AMSCs.