Research progress on the relationship between the TOR signaling pathway regulator, epigenetics, and tumor development

m6A-methylated KCTD21-AS1 regulates macrophage phagocytosis through CD47 and cell autophagy through TIPR

Blocking immune checkpoint CD47/SIRPα is a useful strategy to engineer macrophages for cancer immunotherapy. However, the roles of CD47-related noncoding RNA in regulating macrophage phagocytosis for lung cancer therapy remain unclear. This study aims to investigate the effects of long noncoding RNA (lncRNA) on the phagocytosis of macrophage via CD47 and the proliferation of non-small cell lung cancer (NSCLC) via TIPRL. Our results demonstrate that lncRNA KCTD21-AS1 increases in NSCLC tissues and is associated with poor survival of patients. KCTD21-AS1 and its m6A modification by Mettl14 promote NSCLC cell proliferation. miR-519d-5p gain suppresses the proliferation and metastasis of NSCLC cells by regulating CD47 and TIPRL. Through ceRNA with miR-519d-5p, KCTD21-AS1 regulates the expression of CD47 and TIPRL, which further regulates macrophage phagocytosis and cancer cell autophagy. Low miR-519d-5p in patients with NSCLC corresponds with poor survival. High TIPRL or CD47 levels in patients with NSCLC corresponds with poor survival. In conclusion, we demonstrate that KCTD21-AS1 and its m6A modification promote NSCLC cell proliferation, whereas miR-519d-5p inhibits this process by regulating CD47 and TIPRL expression, which further affects macrophage phagocytosis and cell autophagy. This study provides a strategy through miR-519-5p gain or KCTD21-AS1 depletion for NSCLC therapy by regulating CD47 and TIPRL.

The Pro-Oncogenic Sphingolipid-Metabolizing Enzyme β-Galactosylceramidase Modulates the Proteomic Landscape in BRAF(V600E)-Mutated Human Melanoma Cells

β-Galactosylceramidase (GALC) is a lysosomal enzyme involved in sphingolipid metabolism by removing β-galactosyl moieties from β-galactosylceramide and β-galactosylsphingosine. Previous observations have shown that GALC may exert pro-oncogenic functions in melanoma and Galc silencing, leading to decreased oncogenic activity in murine B16 melanoma cells. The tumor-driving BRAF(V600E) mutation is present in approximately 50% of human melanomas and represents a major therapeutic target. However, such mutation is missing in melanoma B16 cells. Thus, to assess the impact of GALC in human melanoma in a more relevant BRAF-mutated background, we investigated the effect of GALC overexpression on the proteomic landscape of A2058 and A375 human melanoma cells harboring the BRAF(V600E) mutation. The results obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS) demonstrate that significant differences exist in the protein landscape expressed under identical cell culture conditions by A2058 and A375 human melanoma cells, both harboring the same BRAF(V600E)-activating mutation. GALC overexpression resulted in a stronger impact on the proteomic profile of A375 cells when compared to A2058 cells (261 upregulated and 184 downregulated proteins versus 36 and 14 proteins for the two cell types, respectively). Among them, 25 proteins appeared to be upregulated in both A2058-upGALC and A375-upGALC cells, whereas two proteins were significantly downregulated in both GALC-overexpressing cell types. These proteins appear to be involved in melanoma biology, tumor invasion and metastatic dissemination, tumor immune escape, mitochondrial antioxidant activity, endoplasmic reticulum stress responses, autophagy, and/or apoptosis. Notably, analysis of the expression of the corresponding genes in human skin cutaneous melanoma samples (TCGA, Firehose Legacy) using the cBioPortal for Cancer Genomics platform demonstrated a positive correlation between GALC expression and the expression levels of 14 out of the 27 genes investigated, thus supporting the proteomic findings. Overall, these data indicate for the first time that the expression of the lysosomal sphingolipid-metabolizing enzyme GALC may exert a pro-oncogenic impact on the proteomic landscape in BRAF-mutated human melanoma.