Silencing of microRNA-135b inhibits invasion, migration, and stemness of CD24+CD44+ pancreatic cancer stem cells through JADE-1-dependent AKT/mTOR pathway

Abstract

Background: Recent studies have emphasized determining the ability of microRNAs (miRNAs) as crucial regulators in the occurrence and development of pancreatic cancer (PC), which continues to be one of the deadliest malignancies with few effective therapies. The study aimed to investigate the functional role of miR-135b and its associated mechanism to unravel the biological characteristics of tumor growth in pancreatic cancer stem cells (PCSCs). Methods: Microarray analyses were initially performed to identify the PC-related miRNAs and genes. The expression of miR-135b and PCSC markers in PC tissues and cells was determined by RT-qPCR and western blot analysis, respectively. The potential gene (JADE-1) that could bind to miR-135b was confirmed by the dual-luciferase reporter assay. To investigate the tumorigenicity, migration, invasion, and stemness of PC cells, several gain-of-function and loss-offunction genetic experiments were conducted. Finally, tumor formation in nude mice was conducted to confirm the results in vivo. Results: miR-135b was highly-expressed in PC tissues and PCSCs, which was identified to specifically target JADE-1. The overexpression of miR-135b promoted proliferation, migration, and invasion of PCSC, inhibited cell apoptosis and increased the expression of stemness-related factors (Sox-2, Oct-4, Nanog, Aldh1, and Slug). Moreover, miR-135b could promote the expression of phosphorylated AKT and phosphorylated mTOR in the AKT/mTOR pathway. Additionally, miR-135b overexpression accelerated tumor growth in nude mice. Conclusions: Taken together, the silencing of miR-135b promotes the JADE-1 expression, which inactivates the AKT/mTOR pathway and ultimately results in inhibition of self-renewal and tumor growth of PCSCs. Hence, this study contributes to understanding the role of miR-135 in PCSCs and its underlying molecular mechanisms to aid in the development of effective PC therapeutics.

Downregulation of miR-135b-5p Suppresses Progression of Esophageal Cancer and Contributes to the Effect of Cisplatin

“…Zhou J et al demonstrated miR-135b also had higher expression in pancreatic cancer stem cells and tissues. Silencing miR-135b-5p suppressed stemness of pancreatic cancer stem cells by targeting JADE-1 (40). MiRTarBase (23), TargetScan (24), and DIANA-microT (25) predicted the complementary gene of miR-135b-5p.…”

MicroRNA-135b/CAMK2D Axis Contribute to Malignant Progression of Gastric Cancer through EMT Process Remodeling

“…Targeting the miR-135b cluster, which lead to its transcriptional activation, was likely due to amplifying its sequence. At present, upregulated miR-135b has been reported in a variety of cancers, and it has been shown to drive multiple malignant phenotypes [28][29][30]. The amplification of miR-135b in colorectal cancer cells enhanced the chemotherapy resistance for doxorubicin, oxaliplatin, and 5-FU [31,32].…”

Roles of microRNAs in Gastrointestinal Cancer Stem Cell Resistance and Therapeutic Development

“…Transfection with anti-miR-221 was also found to reduce tumor growth in a PDX model of CRC in vivo [49]. Meanwhile, in pancreatic cancer, treatment with anti-miR-135b suppressed tumor growth in vivo [76]. Similarly, treatment with anti-miR-181 decreased the population of EpCAM + HCC stem cells in vivo [108].…”

“…Similarly, the expression of miR-135b was found to be upregulated in CD44 + /CD24 + /EpCAM + CSCs. Inhibiting miR-135b with an antisense oligonucleotide, anti-miR-135b, decreased the expression of stemness markers such as NANOG, ALDH1, SOX2, and OCT-4 [76].…”