Analysis of expression of m 6A regulators in colorectal tumor samples based on TCGA and GEO databases / 中国基层医药

Objective:To detect the expression of N6-methyladenosine (m 6A) regulators in colorectal tumor samples and its clinical significance. Methods:From September to December 2021, the data regarding the expression of m 6A regulators in colorectal tumor samples were collected using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) and the expression of m 6A regulators was compared between different clinical pathological characteristics and between different molecular subtypes. Survival analysis was conducted in patients with colorectal cancer with different m 6A expression levels. Results:In TCGA, insulin-like growth factor 2 mRNA binding protein 1 (IGF2BP1), insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3), and YTH N6-methyladenosine RNA binding protein 1 (YTHDF1) were higher in colorectal tumor samples than normal tissue samples (TCGA-COAD: IGF2BP3: 12.80 vs. 204.46, logFC = 4.00, P = 0.003; YTHDF1: 2 347.56 vs. 3712.77, logFC = 0.66, P < 0.001; TCGA-READ: IGF2BP1: 6.20 vs. 359.32, logFC = 5.82, P = 0.007; YTHDF1: 2 470.10 vs. 4 369.09, logFC = 0.82, P = 0.020). The intersection of TCGA and GEO databases showed that methyltransferase like 14 (METTL14), YTH domain m 6A RNA binding protein 3 (YTHDF3), and α-ketoglutarate dependent dioxygenase AlkB homolog 5 (ALKBH5) were downregulated in colorectal tumor samples compared with normal tissue samples (TCGA-COAD: METTL14: 1 051.56 vs. 711.40, logFC = -0.56, P < 0.001; YTHDF3:4 613.85 vs. 3 155.05, logFC = -0.55, P < 0.001, ALKBH5: 4 250.10 vs. 2 555.55, logFC = -0.73, P < 0.001; TCGA-READ vs. METTL14: 1 113.3 vs. 674.36, logFC = -0.72, P < 0.001; YTHDF3: 5 034.30 vs. 3 331.95, logFC = -0.60, P = 0.004; ALKBH5: 4 902.20 vs. 2 529.71, logFC = -0.95, P < 0.001; GEO-CRC vs. METTL14: 6.58 vs. 6.33, logFC = -0.06, P < 0.001; YTHDF3: 6.28 vs. 6.20, logFC = -0.02, P = 0.002; ALKBH5: 5.07 vs. 4.98, logFC = -0.02, P < 0.001). In colorectal tumor samples of different molecular subtypes, IGF2BP2, HNRNPC, TP53 and YTHDF2 expression was low in KRAS (IGF2BP2: 48.53 vs. 44.04, t = 2.64, P = 0.008; HNRNPC: 121.30 vs. 112.60, t = 2.32, P = 0.020; TP53: 65.30 vs. 60.26, t = 2.11, P = 0.034; YTHDF2: 54.07 vs. 51.19; t = 1.97, P = 0.048). Different clinical pathological characteristics showed that IGF2BP1 was higher in colorectal cancer with positive lymph nodes (8.97 vs. 6.11, W = 20 008, P = 0.002), distant metastasis (8.94 vs. 6.41, W = 19 104, P = 0.009), or stage Ⅲ-Ⅳ (7.46 vs. 7.13, W = 8 779, P = 0.025) than normal tissue. ALKBH5 overexpression, advanced age, presence of vascular invasion, and late pathological staging were significantly related to a short survival period (high ALKBH5 expression vs. low ALKBH5 expression: 5.85 years vs. not available, HR: 1.63, 95% CI: 1.071-2.491, P = 0.021; > 68 years vs. < 68 years: 6.78 years vs. not available, HR: 1.59, 95% CI: 1.049-2.422, P = 0.047; stage Ⅲ-Ⅳ vs. stage Ⅰ-Ⅱ: 4.55 years vs. 8.33 years, HR: 2.89, 95% CI: 1.895-4.425, P < 0.001; presence of vein invasion vs. absence of vein invasion: 5.48 years vs. not available, HR: 2.82, 95% CI: 1.672-4.783, P < 0.001). Conclusion:Some of the m 6A regulators are associated with the biological characteristics and prognosis of colorectal cancer.

Protein Methylation and Interaction with the Antiproliferative Gene, BTG2(/TIS21/Pc3)

The last one and half a decade witnessed an outstanding re-emergence of attention and remarkable progress in the field of protein methylation. In the present article, we describe the early discoveries in research and review the role protein methylation played in the biological function of the antiproliferative gene, BTG2(/TIS21/PC3).

Protein methylation in cellular proliferation and differentiation: Non-histone nuclear methyl acceptor protein(s) during 3'-methyl-4-dimethylaminoazobenzeneinduced hepatocarcinogenesis

An accelerating effect of methyl-deficient diet (MDD) on hepatocarcinogenesis and methylation pattern of nuclear protein(s) by S-adenosylmethionine: protein arginine N-methyltransferase (protein methylase I, PM-I) have been studied with 3'-methyl-4-dimethyl- aminoazobenzene(MeDAB)-treated rats. The MDD+MeDAB-fed group produced typical cancer cells in the liver almost two weeks earlier than the control synthetic diet (CSD)+MeDAB-fed group. Protein methylase I (PM-I) activity in the livers of MDD alone fed rats began to increase at around 2 weeks after MDD-feeding, reaching a peak at 4 weeks and declining thereafter. When nuclei isolated either from normal livers or from cholangiocarcinoma cells were incubated with PM-I preparation from normal liver, 16 and 23-kDa nuclear proteins were the major methylated proteins, regardless of the source of the nuclei. However, when the above mentioned nuclei were incubated with PM-I preparations either from MDD alone fed livers or MDD+ MeDAB-induced cholangiocarcinoma cells, the methylation of 23-kDa protein was not detected. The result suggests that there is a hitherto-unknown PM-I specific to 23 kDa nuclear protein which was lost during methyl deficient diet feeding and hepatocarcinogenesis. The N-terminal 20 amino acids sequence of the 23-kDa protein was found to be (1)Gly-Val-Pro-Leu-(5)X-Arg-Leu-Phe-Asp-(10)His-Ala-Met-Leu-Gln-(15)Ala -His-Arg-Ala-His-(20)Glu, having 94.7% sequence homology with human chorionic somatomammotropin precursor A and B.