tRNA Modifying Enzymes, NSUN2 and METTL1, Determine Sensitivity to 5-Fluorouracil in HeLa Cells

Abstract

Nonessential tRNA modifications by methyltransferases are evolutionarily conserved and have been reported to stabilize mature tRNA molecules and prevent rapid tRNA decay (RTD). The tRNA modifying enzymes, NSUN2 and METTL1, are mammalian orthologs of yeast Trm4 and Trm8, which are required for protecting tRNA against RTD. A simultaneous overexpression of NSUN2 and METTL1 is widely observed among human cancers suggesting that targeting of both proteins provides a novel powerful strategy for cancer chemotherapy. Here, we show that combined knockdown of NSUN2 and METTL1 in HeLa cells drastically potentiate sensitivity of cells to 5-fluorouracil (5-FU) whereas heat stress of cells revealed no effects. Since NSUN2 and METTL1 are phosphorylated by Aurora-B and Akt, respectively, and their tRNA modifying activities are suppressed by phosphorylation, overexpression of constitutively dephosphorylated forms of both methyltransferases is able to suppress 5-FU sensitivity. Thus, NSUN2 and METTL1 are implicated in 5-FU sensitivity in HeLa cells. Interfering with methylation of tRNAs might provide a promising rationale to improve 5-FU chemotherapy of cancer.

NOP2/Sun RNA methyltransferase 2 promotes tumor progression via its interacting partner RPL6 in gallbladder carcinoma

“…In terms of tumor malignancy, the NSUN2 gene copy number was increased in oral and colorectal cancers, 10 and NSUN2 were implicated in 5-FU sensitivity in HeLa cells. 28 Herein, we for the first time identified the m 5 C methyltransferase NSUN2 as a tumor accelerator in GBC, and this gene was highly expressed in GBC as compared with normal or cholecystitis tissues. NSUN2 enhanced the GBC cell proliferation rate and colony formation ability.…”

“…By methylating specific subsets of RNA (at m5C), such as the CDK1 3′UTR and the P27 5′ UTR, NSUN2 is a critical regulator of the cell proliferative state. In terms of tumor malignancy, the NSUN2 gene copy number was increased in oral and colorectal cancers, and NSUN2 were implicated in 5‐FU sensitivity in HeLa cells …”

Elucidation of the genetic and epigenetic landscape alterations in RNA binding proteins in glioblastoma

“…Certainly, in our analysis, we found RBPs that were already reported to contribute to the aggressiveness of the high grade cancers. These included IGF2BP3 [34, 54], S100A4 [59, 60], METTL1 [51], NPM1 [61, 62], BST2 [63], and EIF4E2 [64]. We also validated the role of two upregulated and aggressiveness related RBPs (METTL1 and OAS1) in chemoresistance of LN229 glioma cells to temozolomide.…”

“…This protein is known to methylate tRNAs. Moreover, its expression may impart chemo-resistance in HeLa cells [51]. ELAVL2 is the gene found to be deleted in maximum percentage of cases in our analysis.…”

Two-subunit enzymes involved in eukaryotic post-transcriptional tRNA modification

“…80 Interestingly, human METTL1 was found to be inactivated by phosphorylation at Ser27 by protein kinase B, suggesting a possible mechanism to regulate m 7 G modification levels in the cell. 81 By contrast, in bacteria m 7 G 46 is formed by the Trm8 homolog TrmB alone, based on the apparent absence of Trm82 homologs, 82 the activity of purified E. coli TrmB, 83 and the ability of E. coli TrmB to complement the lack of Sc Trm8-Trm82 in S. cerevisiae trm8D trm82D double mutants.…”