| Summary: | 碩士 === 國立陽明大學 === 生命科學系暨基因體科學研究所 === 105 === Cancer stem cells (CSCs), the rare population cells with stem-like properties in tumor, are regarded as the main causes of tumor metastasis and recurrence. Previous studies showed that lactate, a metabolite of glycolysis would accumulate in tumor microenvironment and may affect the tumor development. Recently, we found that tumor cells treated with lactate posed more CSC properties and showed higher expression levels of stemness and EMT related genes. However, the mechanisms of lactate-mediated stemness regulation remain unclear.
Increasing histone acetylation is proposed for lactate effects. To investigate the underlying mechanisms, we evaluated the stemness gene expression under lactate treatment in two NPC cell lines, TW01 and HONE1. Under 10 mM lactate treatment, increasing expression of stemness genes was detected by Western blotting and RT-qPCR. The results were consistent with the previous results in our lab. To verify whether lactate increase the concentration of acetyl-CoA to promote histone acetylation, we measured the concentration after lactate treatment. The data showed that lactate treatment enhanced the concentration of acetyl-CoA. Moreover, to clarify whether lactate affected gene expressions through increasing histone acetylation, we extracted histone from the treated cells and assessed the acetylation level by immunoprecipitation and Western blotting. We found that acetylation of histones was increased after lactate treatment, especially in histone H3.
We then used CHIP assay to evaluate the status of histone H3 acetylation, in some stemness genes, such as Oct4, Nanog etc. The result indicated that lactate would promote acetylation at promoter of target genes and then enhanced the expression of stemness genes, Oct4 and Nanog.
In summary, these findings showed that lactate increased the expression of stemness genes, Oct4 and Nanog through increasing acetylation of histone H3 at promoter region. Thus, it implied that lactate, the most aboundant metabolite in tumor microenvironment, could promote malignancy of NPC by leading differentiated cancer cells into CSCs and increased expression level of stemness genes in both differentiated cancer cells and CSCs.
|
|---|
