ABSTRACT
BACKGROUND: Lipid droplet formation is a prominent histological feature in clear cell renal cell carcinoma (ccRCC), but the significance and mechanisms underlying lipid droplet accumulation remain unclear. METHODS: Expression and clinical significance of MT1G in ccRCC were analyzed by using TCGA data, GEO data and scRNASeq data. MT1G overexpression or knockdown ccRCC cell lines were constructed and in situ ccRCC model, lung metastasis assay, metabolomics and lipid droplets staining were performed to explore the role of MT1G on lipid droplet accumulation in ccRCC. RESULTS: Initially, we observed low MT1G expression in ccRCC tissues, whereas high MT1G expression correlated with advanced disease stage and poorer prognosis. Elevated MT1G expression promoted ccRCC growth and metastasis both in vitro and in vivo. Mechanistically, MT1G significantly suppressed acylcarnitine levels and downstream tricarboxylic acid (TCA) cycle activity, resulting in increased fatty acid and lipid accumulation without affecting cholesterol metabolism. Notably, MT1G inhibited H3K14 trimethylation (H3K14me3) modification. Under these conditions, MT1G-mediated H3K14me3 was recruited to the CPT1B promoter through direct interaction with specific promoter regions, leading to reduced CPT1B transcription and translation. CONCLUSIONS: Our study unveils a novel mechanism of lipid droplet accumulation in ccRCC, where MT1G inhibits CPT1B expression through modulation of H3K14 trimethylation, consequently enhancing lipid droplet accumulation and promoting ccRCC progression. Graphical abstract figure Schematic diagram illustrating MT1G/H3K14me3/CPT1B-mediated lipid droplet accumulation promoted ccRCC progression via FAO inhibition.
Subject(s)
Carcinoma, Renal Cell , Disease Progression , Kidney Neoplasms , Lipid Droplets , Humans , Carcinoma, Renal Cell/pathology , Carcinoma, Renal Cell/metabolism , Carcinoma, Renal Cell/genetics , Kidney Neoplasms/pathology , Kidney Neoplasms/metabolism , Kidney Neoplasms/genetics , Lipid Droplets/metabolism , Animals , Mice , Histones/metabolism , Histones/genetics , Cell Line, Tumor , Carnitine O-Palmitoyltransferase/genetics , Carnitine O-Palmitoyltransferase/metabolism , Methylation , Gene Expression Regulation, Neoplastic , Male , Female , Prognosis , Mice, Nude , Cell ProliferationABSTRACT
Key gene mutations are essential for colorectal cancer (CRC) development; however, how the mutated tumor cells impact the surrounding normal cells to promote tumor progression has not been well defined. Here, we report that PIK3CA mutant tumor cells transmit oncogenic signals and result in malignant transformation of intestinal epithelial cells (IECs) via paracrine exosomal arachidonic acid (AA)-induced H3K4 trimethylation. Mechanistically, PIK3CA mutations sustain SGK3-FBW7-mediated stability of the cPLA2 protein, leading to the synthetic increase in AA, which is transported through exosome and accumulated in IECs. Transferred AA directly binds Menin and strengthens the interactions of Menin and MLL1/2 methyltransferase. Finally, the combination of VTP50469, an inhibitor of the Menin-MLL interaction, and alpelisib synergistically represses PDX tumors harboring PIK3CA mutations. Together, these findings unveil the metabolic link between PIK3CA mutant tumor cells and the IECs, highlighting AA as the potential target for the treatment of patients with CRC harboring PIK3CA mutations.
Subject(s)
Arachidonic Acid , Cell Transformation, Neoplastic , Chromatin Assembly and Disassembly , Class I Phosphatidylinositol 3-Kinases , Mutation , Class I Phosphatidylinositol 3-Kinases/genetics , Class I Phosphatidylinositol 3-Kinases/metabolism , Humans , Arachidonic Acid/metabolism , Animals , Mutation/genetics , Cell Transformation, Neoplastic/genetics , Cell Transformation, Neoplastic/metabolism , Cell Transformation, Neoplastic/pathology , Chromatin Assembly and Disassembly/genetics , Mice , Cell Line, Tumor , Colon/pathology , Colon/metabolism , Colorectal Neoplasms/genetics , Colorectal Neoplasms/pathology , Colorectal Neoplasms/metabolism , Exosomes/metabolism , Exosomes/genetics , Intestinal Mucosa/metabolism , Intestinal Mucosa/pathology , Histones/metabolism , Histones/geneticsABSTRACT
Betulinic acid (BA) is a pentacyclic triterpene found in many plant species and has a broad-spectrum anti-tumor effect in various cancers, including colon cancer (CRC). However, its anticancer mechanism in CRC is no clear. RNA sequencing and bioinformatics analysis showed BA up-regulated 378 genes and down-regulated 137 genes in HT29 cells, while 2303 up-regulated and 1041 down-regulated genes were found in SW480 cells. KEGG enrichment analysis showed BA significantly stimulated the expression of metallothionein 1 (MT1) family genes in both HT29 and SW480 cells. Metallothionein 1G (MT1G) was the gene with the highest upregulation of MT1 family genes induced by BA dose-dependently. High MT1G expression enhanced the sensitivity of CRC cells to BA, whereas, MT1G knockdown had the opposite effect in vitro and in vivo. GSEA and GSCA showed genes affected by BA treatment were involved in cell cycle and G2/M checkpoint in CRC. Flow cytometry further exhibited BA reduced the percentage of G0/G1 cells and increased the percentage of G2/M cells in a dose-dependent manner, which could be rescued by MT1G knockdown. Moreover, MT1G also counteracted the BA-induced changes in cell cycle-related proteins (CDK2 and CDK4) and p-Rb. In summary, we have revealed a new anti-tumor mechanism that BA altered the cell cycle progression of CRC cells by upregulating MT1G gene, thereby inhibiting the proliferation of CRC cells.