METTL3 Promotes Osteosarcoma Metastasis via an m6A-dependent Epigenetic Activity of CBX4.

BACKGROUND: Osteosarcoma cells are prone to metastasis, and the mechanism of N6-methyladenosine (m6A) methylation modification in this process is still unclear. Methylation modification of m6A plays an important role in the development of osteosarcoma, which is mainly due to abnormal expression of enzymes related to methylation modification of m6A, which in turn leads to changes in the methylation level of downstream target genes messenger RNA (mRNA) leading to tumor development. METHODS: We analyzed the expression levels of m6A methylation modification-related enzyme genes in GSE12865 whole-genome sequencing data. And we used shRNA (short hairpin RNA) lentiviral interference to interfere with METTL3 (Methyltransferase 3) expression in osteosarcoma cells. We studied the cytological function of METTL3 by Cell Counting Kit-8 (CCK8), flow cytometry, migration and other experiments, and the molecular mechanism of METTL3 by RIP (RNA binding protein immunoprecipitation), Western blot and other experiments. RESULTS: We found that METTL3 is abnormally highly expressed in osteosarcoma and interferes with METTL3 expression in osteosarcoma cells to inhibit metastasis, proliferation, and apoptosis of osteosarcoma cells. We subsequently found that METTL3 binds to the mRNA of CBX4 (chromobox homolog 4), a very important regulatory protein in osteosarcoma metastasis, and METTL3 regulates the mRNA and protein expression of CBX4. Further studies revealed that METTL3 inhibited metastasis of osteosarcoma cells by regulating CBX4. METTL3 has been found to be involved in osteosarcoma cells metastasis by CBX4 affecting the protein expression of matrix metalloproteinase 2 (MMP2), MMP9, E-Cadherin and N-Cadherin associated with osteosarcoma cells metastasis. CONCLUSIONS: These results suggest that the combined action of METTL3 and CBX4 plays an important role in the regulation of metastasis of osteosarcoma, and therefore, the METTL3-CBX4 axis pathway may be a new potential therapeutic target for osteosarcoma.

Ellagic acid induces apoptosis and autophagy in colon cancer through the AMPK/mTOR pathway.

Ellagic acid (EA), found in fruits and foods, has been shown to be effective in the treatment of breast, colon and bladder cancer. However, due to the complexity of colon cancer, the therapeutic mechanism of EA for colon cancer is still unclear. Cell Counting Kit-8 (CCK-8) assay were employed to investigate the cell proliferation. Western blotting and flow cytometry assays were utilized to investigate apoptosis and autophagy in CRC cells (HCT116), respectively. Moreover, western blotting and luciferase reporter assays were evaluated the effect of EA on AMPK/mTOR pathway. Through flow cytometry analysis, EA could promote the apoptosis of HCT116 cells. In addition, EA can reduce the phosphorylation of mTOR, promoted phosphorylation of AMPK, and induced autophagy in HCT116 cells. Also, Dorsomorphin pretreatment can reduce the expression of autophagy protein, which indicates that EA induces autophagy through AMPK/mTOR pathway. These results suggest that EA inhibits the growth of colon cancer through AMPK/mTOR pathway and induces apoptosis and protective autophagy.

Co­expression of the carbamoyl­phosphate synthase 1 gene and its long non­coding RNA correlates with poor prognosis of patients with intrahepatic cholangiocarcinoma.

The mechanisms leading to high rates of malignancy and recurrence of human intrahepatic cholangiocarcinoma (ICC) remain unclear. It is difficult to diagnose and assess the prognosis of patients with ICC in the clinic due to the lack of specific biomarkers. In addition, long non­coding RNAs (lncRNAs) have been reported to serve important roles in certain types of tumorigenesis however a role in ICC remains to be reported. The aim of the current study was to screen for genes and lncRNAs that are abnormally expressed in ICC and to investigate their biological and clinicopathological significance in ICC. The global gene and lncRNA expression profiles in ICC were measured using bioinformatics analysis. Carbamoyl­phosphate synthase 1 (CPS1) and its lncRNA CPS1 intronic transcript 1 (CPS1­IT1) were observed to be upregulated in ICC. The expression of CPS1 and CPS1­IT1 was measured in 31 tissue samples from patients with ICC and a number of cell lines. The effects of CPS1 and CPS1­IT1 on the proliferation and apoptosis of the ICC­9810 cell line were measured. In addition, the clinicopathological features and survival rates of patients with ICC with respect to the gene and lncRNA expression status were analyzed. CPS1 and CPS1­IT1 were co­upregulated in ICC tissues compared with non­cancerous tissues. Knockdown of CPS1 andor CPS1­IT1 reduced the proliferation and increased the apoptosis of ICC­9810 cells. Additionally, clinical analysis indicated that CPS1 and CPS1­IT1 were associated with poor liver function and reduced survival rates when the relative expression values were greater than 4 in cancer tissues. The comparisons between the high CPS1 expression group and the low expression group indicated significant differences in international normalized ratio (P=0.048), total protein (P=0.049), indirect bilirubin (P=0.025), alkaline phosphatase (P=0.003) and disease­free survival (P=0.034). In addition, there were differential trends in CA19­9 (P=0.068), globulin (P=0.052) and total bilirubin (P=0.066). The comparisons between the high CPS1­IT1 expression group and the low expression group indicated significant differences in lymphatic invasion (P=0.045), carbohydrate antigen 19­9 (P=0.044), disease­free survival (P=0.026), and non­significant differential trends in alkaline phosphatase were observed (P=0.085). In conclusion, CPS1 and CPS1­IT1 may serve an important role in ICC development by promoting the proliferation of ICC cells. Furthermore, CPS1 and CPS1­IT1 were associated with poor liver function and reduced survival rates. Thus, CPS1 and CPS1­IT1 may be potential prognostic indicators for patients with ICC.