Targeted downregulation of checkpoint kinase 1 (CHEK1), a markedly elevated oncogene activator in patients with cholangiocarcinoma (CCA), suppresses metastasis and proliferation of CCA cells by using human umbilical cord mesenchymal stem cells, according to new findings from a study published in Cell Death Discovery.

CHEK1 expression correlated with CCA tumor size, tumor stage, and lymph node metastasis (P <.05), regardless of the gender or age of the patient.

Researchers from the Fourth Affiliated Hospital of China Medical University in Shenyang collected biopsy samples from 145 patients diagnosed with CCA between January 2009 and December 2014 and 35 control tissue samples from normal bile ducts following liver transplantation. Lymph node metastasis had occurred in 45 of these 145 patients.


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The researchers cultured human stem cells from umbilical cords provided with the consent of 3 pregnant women who underwent cesarian sections. They isolated purified human stem cell exosomes by ultracentrifuging the cultured tissues.

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Using a reagent, they transfected cells with CCA, some of which they transplanted via injection into mice, for both in vitro and in vivo experiments. After 48 hours, the investigators confirmed the transfection efficacy using a Western blot assay and reverse transcription kits.

The researchers determined that the miRNA miR-15a-5p regulated CHEK1 expression, thus contributing to CCA tumor progression. When miR-15a-5p targeted the CHEK1 oncogene, it downregulated CHEK1 protein levels. MiR-15a-5p is highly expressed in human umbilical cord mesenchymal stem cells and their exosomes.

In this experiment, the investigators confirmed that the human umbilical cord mesenchymal stem cell exosomes, specifically containing miR-15a-5p, suppressed the metastasis, malignant proliferation, and epithelial-mesenchymal transition of CCA cells by promoting cellular apoptosis. They used flow cytometry to assess cellular apoptosis, used the Transwell assay to determine tumor metastasis, and measured cellular density to assess proliferation.

“Our findings suggested important roles of the miR-15a-5p/CHEK1 axis in CCA progression,” the authors concluded. “Our finding of [human umbilical cord mesenchymal stem cell exosomes] expressing miR-15a-5p yielded promising options that miR-15a-5p might be a potential therapeutic strategy as a CCA.”

Reference

Li N, Wang B. Suppressive effects of umbilical cord mesenchymal stem cell-derived exosomal miR-15a-5p on the progression of cholangiocarcinoma by inhibiting CHEK1 expression. Cell Death Discov. 2022;8(1):1-11. doi:10.1038/s41420-022-00932-7