Cancer-associated fibroblasts promote stemness maintenance and gemcitabine resistance via HIF-1α/miR-21 axis under hypoxic conditions in pancreatic cancer.

Gemcitabine (GEM) resistance affects chemotherapy efficacy of pancreatic cancer (PC). Cancer-associated fibroblasts (CAFs) possess the ability of regulating chemoresistance. This study probed the mechanism of hypoxia-treated CAFs regulating cell stemness and GEM resistance in PC. Miapaca-2/SW1990 were co-cultured with PC-derived CAFs under normoxic/hypoxic conditions. Cell viability/self-renewal ability was determined by MTT/sphere formation assays, respectively. Protein levels of CD44, CD133, Oct4, and Sox2 were determined by western blot. GEM tumoricidal assay was performed. PC cell GEM resistance was evaluated by MTT assay. CAFs were cultured at normoxia/hypoxia. HIF-1α and miR-21 expression levels were assessed by RT-qPCR and western blot, with their binding sites and binding relationship predicted and verified. CAF-extracellular vesicles (EVs) were incubated with Miapaca-2 cells. The RAS/AKT/ERK pathway activation was detected by western blot. PC xenograft models were established and treated with hypoxic CAF-EVs and GEM. CAFs and PC cell co-culture increased cell stemness maintenance, GEM resistance, cell viability, stem cell sphere number, and protein levels of CD44, CD133, Oct4, and Sox2, and weakened GEM tumoricidal ability to PC cells, with the effects further enhanced by hypoxia. Hypoxia induced HIF-1α and miR-21 overexpression in CAFs. Hypoxia promoted CAFs to secrete high-level miR-21 EVs via the HIF-1α/miR-21 axis, and activated the miR-21/RAS/AKT/ERK pathway. CAF-EVs promoted GEM resistance in PC via the miR-21/RAS/ATK/ERK pathway in vivo. Hypoxia promoted CAFs to secrete high-level miR-21 EVs through the HIF-1α/miR-21 axis, and activated the miR-21/RAS/AKT/ERK pathway via EVs to trigger stemness maintenance and GEM resistance in PC.

Abnormal expression of serum miR-4746-5p in liver cancer patients after interventional chemotherapy and its possible mechanism.

Interventional chemotherapy is a common operation in the clinical treatment of liver cancer. The aim of this study was to investigate the expression and molecular mechanism of serum miR-4746-5p in liver cancer patients before and after interventional chemotherapy. The levels of miR-4746-5p and CDKN1C in serum samples from liver cancer patients were detected using real-time fluorescence quantitative polymerase chain reaction. Receiver operating characteristic curves revealed the diagnostic value of miR-4746-5p in tumors. Differences in clinical indicators between liver cancer patients and healthy controls were assessed using Pearson correlation analysis. Luciferase reporter gene assays confirmed the targeted interaction between miR-4746-5p and CDKN1C. In vitro cellular assays were validated by Cell Counting Kit-8, Transwell assay, and chemoresistance assay. Serum miR-4746-5p levels were increased in liver cancer patients but were downregulated after chemotherapy intervention. CDKN1C expression showed the opposite trend. Low levels of miR-4746-5p mediated cell growth and metastasis by targeting and negatively regulating CDKN1C expression, while silencing CDKN1C restored cell activity. Inhibition of miR-4746-5p reduced chemoresistance, while downregulation of CDKN1C affected cell sensitivity. miR-4746-5p may be a potential therapeutic factor for liver cancer diagnosis and interventional chemotherapy.

Mechanism of immune escape mediated by receptor tyrosine kinase KIT in thyroid cancer.

OBJECTIVE: Thyroid cancer (TC) is one of the fastest-growing malignant tumors. This study sought to explore the mechanism of immune escape mediated by receptor tyrosine kinase (KIT) in TC. METHODS: The expression microarray of TC was acquired through the GEO database, and the difference analysis and Kyoto encyclopedia of genes and genomes pathway enrichment analysis were carried out. KIT levels in TC cell lines (K1/SW579/BCPAP) and human normal thyroid cells were detected using reverse transcription quantitative polymerase chain reaction and western blot analysis. TC cells were transfected with overexpressed (oe)-KIT and CD8+ T cells were cocultured with SW579 cells. Subsequently, cell proliferation, migration, and invasion abilities, CD8+ T cell proliferation, cytokine levels (interferon-γ [IFN-γ]/tumor necrosis factor-α [TNF-α]) were determined using colony formation assay, Transwell assays, flow cytometry, and enzyme-linked immunosorbent assay. The phosphorylation of MAPK pathway-related protein (ERK) was measured by western blot analysis. After transfection with oe-KIT, cells were treated with anisomycin (an activator of the MAPK pathway), and the protein levels of p-ERK/ERK and programmed death-ligand 1 (PD-L1) were detected. RESULTS: Differentially expressed genes (N = 2472) were obtained from the GEO database. KIT was reduced in TC samples and lower in tumor cells than those in normal cells. Overexpression of KIT inhibited immune escape of TC cells. Specifically, the proliferation, migration, and invasion abilities of TC cells were lowered, the proliferation level of CD8+ T cells was elevated, and IFN-γ and TNF-α levels were increased. KIT inhibited the activation of the MAPK pathway in TC cells and downregulated PD-L1. CONCLUSION: KIT suppressed immune escape of TC by blocking the activation of the MAPK pathway and downregulating PD-L1.