N6-methyladenosine mediates the cellular proliferation and apoptosis via microRNAs in arsenite-transformed cells.

N6-methyladenosine (m6A) modification is implicated to play an important role in cellular biological processes, but its regulatory mechanisms in arsenite-induced carcinogenesis are largely unknown. Here, human bronchial epithelial (HBE) cells were chronically treated with 2.5 µM arsenite sodium (NaAsO2) for about 13 weeks and these cells were identified with malignant phenotype which was demonstrated by increased levels of cellular proliferation, percentages of plate colony formation and soft agar clone formation, and high potential of resistance to apoptotic induction. Our results firstly demonstrated that m6A modification on RNA was significantly increased in arsenite-transformed cells and this modification may be synergistically regulated by methyltransferase-like 3 (METTL3), methyltransferase-like 14 (METTL14), Wilms tumor 1-associated protein (WTAP) and Fat mass and obesity-associated protein (FTO). In addition, knocking down of METTL3 in arsenite-transformed cells can dramatically reverse the malignant phenotype, which was manifested by lower percentages of clone and colony formation as well as higher rates of apoptotic induction. Given the critical roles of miRNAs in cellular proliferation and apoptosis, miRNAs regulated by m6A in arsenite-transformed cells were analyzed by Venn diagram and KEGG pathway in this study. The results showed that these m6A-mediated miRNAs can regulate pathways which are closely associated with cellular proliferation and apoptosis, implicating that these miRNAs may be the critical bridge by which m6A mediates dysregulation of cell survival and apoptosis in arsenite-transformed cells. Taken together, our results firstly demonstrated the significant role of m6A in the prevention of tumor occurrence and progression induced by arsenite.

The selectivity of artemisinin-based drugs on human lung normal and cancer cells.

Artemisinin-based drugs are documented to possess anticancer potential that is selectively effective to cancer cells. However, this selectivity is disputable in different studies and the mechanism is still unclear. To clarify this discrepancy, this study employed five assays to evaluate the cytotoxic effects of artemisinin and artesunate on normal human bronchial epithelial (HBE) cells and lung adenocarcinoma A549 cells. The results of five cytotoxic assays coherently showed that artemisinin and artesunate caused dose-dependent cytotoxicity in both HBE and A549 cells with a slight selectivity to A549 cells. Further, both HBE cells and A549 cells demonstrated elevated levels of intracellular reactive oxygen species (ROS) and increased DNA damage. Since artemisinin and artesunate exerted significant cytotoxic effect on both normal cells and cancer cells via the same pathway of ROS-mediated DNA damage, the side effects of artemisinin and artesunate on normal cell cannot be ignored when developing their antitumor effects.

[miR-155/BACH1 Signaling Pathway in Human Lung Adenocarcinoma Cell Death Induced by Arsenic Trioxide].

OBJECTIVE: To explore the changes of micro RNA 155 (miR-155),BTB and CNC homologous protein 1 (BACH1),quinone oxidoreductase 1 (NQO1) and heme-oxygenase-1 (HO-1) in the process of arsenic trioxide-induced cell death,and to clarify the relationship between miR-155 and BACH1,providing experimental basis for the sensitivity of arsenic trioxide (ATO) treatment. METHODS: Human lung adenocarcinoma cell line A549 cells were treated with different concentrations of ATO. MTT assay and total antioxidant capacity detection kit were used to determine cell viability and total antioxidant capacity,respectively. BACH1,NQO1 and HO-1 protein expression were probed by Western blot and real-time fluorescence quantitative (qRT-PCR) was utilized to test the miR-155 level. A549 cells were transfected with miR-155 mimic and its negative control,then the expression level of miR-155 was detected by qRT-PCR,and these cells were treated with 20 µmol/L for 24 h followed by MTT and Western blot detection. RESULTS: 10 µmol/L ATO significantly reduced the cell viability in A549 cells. 10 µmol/L and 20 µmol/L ATO treatment activated BACH1 expression and inhibited miR-155,NQO1 and HO-1 expression,leading to decreased total antioxidant capacity. Importantly,the cell death induced by 20 µmol/L ATO was significantly decreased in miR-155 mimic transfection cells in comparison with non-transfected cells and miR-155 mimic negative control transfected cells. Moreover,high expression of miR-155 reduced BACH1 activation and increased NQO1 and HO-1 expression in cells treated with 20 µmol/L ATO ( P<0.05). CONCLUSION: Restraining total antioxidant capacity contributes to ATO induced cell death,the underlying mechanisms may be that ATO can activate BACH1 expression through inhibition of the miR-155 level,leading to subsequent inhibition of NQO1 and HO-1 expression. Taken together,these data suggest that miR-155 and BACH1 could be used as sensitivity targets for ATO treatment in lung cancer.

Large intergenic non-coding RNA-ROR as a potential biomarker for the diagnosis and dynamic monitoring of breast cancer.

BACKGROUND: Recent study has revealed that large intergenic non-coding RNA-ROR (linc-ROR) is aberrantly expressed in a number of cancers including breast cancer. However, whether circulating linc-ROR in plasma could be used for breast cancer diagnosis and dynamic monitoring is not clear. OBJECTIVE: The objective of this study is to determine if plasma linc-ROR could be applied as a biomarker for the diagnosis and dynamic monitoring of breast cancer. METHODS: We tested the expression levels of linc-ROR in 24 pairs of tissue samples and 96 plasma samples from breast cancer patients by quantitative real time-polymerase chain reaction (qRT-PCR), and analyzed the correlation between plasma linc-ROR levels and clinico-pathological characteristics. Receiver operating characteristic (ROC) curve was used to assess the diagnostic power of plasma linc-ROR, carcinoembryonic antigen (CEA) and carbohydrate antigen (CA)153 for breast cancer. Furthermore, we explored the monitoring values of plasma linc-ROR for breast cancer by analyzing the preoperative and postoperative plasma linc-ROR levels of the same patients. RESULTS: The expression levels of linc-ROR were significantly higher in breast cancer tissues and plasma than the levels in the control (P< 0.05). The linc-ROR expression levels in plasma were correlated with lymph node metastasis (P< 0.05), estrogen receptor (ER) (P< 0.05) and progesterone receptor (PR) (P< 0.05). The area under the ROC curve of plasma linc-ROR was 0.758 (sensitivity 80.0%; specificity 73.3%), which was higher than CEA and CA153 values from the same patients obtained. Combination of the linc-ROR with the conventional biomarkers might produce better diagnostic ability. Additionally, the linc-ROR expression levels of plasma in postoperative patients were lower than those in preoperative patients (P< 0.05). CONCLUSION: Overexpressed linc-ROR may be a potential biomarker for the diagnosis and dynamic monitoring of breast cancer.

Dihydroartemisinin Sensitizes Human Lung Adenocarcinoma A549 Cells to Arsenic Trioxide via Apoptosis.

Recent studies have shown that arsenic trioxide (ATO) is an effective anti-cancer drug for treatment of acute promyelocytic leukemia and other types of human cancer. However, we have found that lung cancer cells constantly develop a high level of resistance to ATO. In this study, we have explored a possibility of combination of dihydroartemisinin (DHA) and ATO treatments to reduce ATO resistance of lung cancer cells. We determined the combinatory effects of DHA and ATO on cytotoxicity of human lung adenocarcinoma (A549) cells. We showed that co-exposure to DHA and ATO of A549 cells synergistically increased the cytotoxicity and apoptotic cell death in the cells. We found that the synergistic effect of DHA and ATO in promoting apoptosis mainly resulted from increased cellular level of reactive oxygen species (ROS) and DNA damage. ATO alone only exerted moderate growth inhibitory effects on A549 cells. The results indicate that DHA can significantly sensitize ATO-induced cytotoxicity of A549 lung cancer cells through apoptosis mediated by ROS-induced DNA damage. Interestingly, we found that the combinatory treatment of DHA and ATO did not result in significant adverse effects in normal human bronchial epithelial (HBE) cells. Our results further provide evidence for the potential application of combinatory effects of DHA and ATO as a safe therapy for human lung cancer.