Arsenic trioxide is valuable for treatment of promyelocytic leukemia, but less attention has been paid to its therapeutic potential for other cancers. In this study, the effects of arsenic trioxide were tested in human pancreatic (AsPC-1), colonic (HT-29), and breast (MCF-7) cancer cells. In all three cancer cell lines, arsenic trioxide inhibited proliferation in a concentration and time-dependent manner, as measured by 3H-methyl thymidine incorporation and cell counting. Coincident with inhibition of growth, arsenic trioxide induced marked morphologic changes, including reduced cytoplasmic volume, membrane blebbing, and nuclear condensation consistent with apoptosis. Propidium iodide DNA staining at 24 hours revealed cell cycle arrest in the G0/G1 phase and an increase in the S phase, while at 72 hr there was G2/M phase arrest with a marked increase in the sub-G0/G1, apoptotic cell population. The DNA fragmentation induced by arsenic trioxide was confirmed by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assay in all cell lines. Western blot analysis revealed activation of caspase -3, -7, and -9 by arsenic trioxide. Caspase-3 activity was confirmed by demonstrating cleavage of its downstream target, poly ADP-ribose polymerase (PARP). Expression of the antiapoptosis protein, Bcl-2, was time-dependently decreased. In contrast, arsenic trioxide markedly enhanced the expression of the p21 protein, GADD45 and GADD153, in a time-dependent manner. These findings suggest that arsenic trioxide has potential as a therapeutic agent for these cancers.
Background Growing evidences have been revealing that long noncoding RNAs are vital factors in oncogenesis and tumor development. Among them, cancer susceptibility candidate 11 (CASC11) has displayed an impressively essential role in various kinds of cancers including hepatocellular carcinoma (HCC). Nevertheless, its role and potential mechanism in HCC still remain to be fully investigated. Methods CASC11 expression level was evaluated by real‐time polymerase chain reaction, western blotting, and in situ hybridization staining in HCC patients, and its prognostic effect was analyzed. The role of CASC11 in HCC tumorigenesis and progression was investigated by cell proliferation assay, transwell assay, extracellular acidification rate, western blotting, flow cytometry, and an in vivo xenograft model. The interactions among CASC11, E2F transcription factor 1 (E2F1), and eukaryotic translation initiation factor 4A3 (EIF4A3) were explored by using quantitative reverse transcriptase polymerase chain reaction, western blotting, RNA‐binding protein immunoprecipitation assay, and chromatin immunoprecipitation assays. Results Upregulation of CASC11 was confirmed in HCC tissues and associated with poor prognosis. Loss of function assays showed inhibition of CASC11 expression suppressed HCC cells proliferation, mobility, and glucose metabolism and promoted apoptosis. E2F1 expression significantly decreased after inhibition of CASC11. Rescue experiments illustrated that E2F1 overexpression alleviated the suppression of CASC11 inhibition on HCC progression in vitro and in vivo. Mechanistically, CASC11 recruited EIF4A3 to enhance the stability of E2F1 mRNA. CASC11 and E2F1 impacted the activation of the NF‐κB signaling and PI3K/AKT/mTOR pathway and further regulated the expression PD‐L1 that is an important target of immunotherapy. In addition, we identified YY1 could modulate CASC11 expression by binding to its promoter. Conclusions Our data revealed that CASC11 promoted the progression of HCC by means of EIF4A3‐mediated E2F1 upregulation, indicating CASC11 is a promising diagnostic biomarker and therapeutic target for HCC.
We have previously shown that arsenic trioxide blocks proliferation and induces apoptosis in human pancreatic cancer cells at low, non-toxic concentrations. The mechanisms of the apoptosis was investigated in MiaPaCa2 and PANC-1 cells that have been previously shown to be responsive to arsenic trioxide. The results show the caspase-3, caspase-7, and caspase-9 are all activated by arsenic trioxide, together with cleavage of the downstream caspase-3 target poly ADP ribose polymerase (PARP). Expression of the anti-apoptosis proteins, Bcl-2 and Mcl-1 expression decreased time-dependently while Bax expression increased. These findings indicate that the Bcl family of proteins, the mitochondrial pathway and activation of the caspase cascade are responsible for arsenic-induced apoptosis. Flow cytometric analysis revealed changes of cell cycle distribution from a G0/G1 phase arrest at 24 hours to G2/M phase arrest at 72 hours following arsenic treatment. The sub-G0/G1 cell population of apoptotic cells was increased at these times. Arsenic increased expression of the P21 protein and decreased levels of cyclin A, cyclin B1 and cyclin D1, but expression of CDK2, CDK4, CDK6, and cyclin E were not affected. Arsenic trioxide markedly enhanced the expression of GADD45 and GADD153 in a time-dependent manner. In summary, arsenic trioxide induced apoptosis in pancreatic cancer cells through activating the caspase cascade via the mitochondrial pathway, GADD expression and by modifying cell cycle progress and changes in several cycle-regulating proteins. This old drug may be valuable for treatment of pancreatic cancer.
Probiotics play an important role against infectious pathogens via their effects on the epithelium, the production of antimicrobial compounds, and competitive exclusion. Administration of probiotic supplements may reduce the risk of infectious diseases and the use of antibiotics, hence contributing to a reduction or a delay of the development of multi-resistant bacteria. Infection is a constant concern for people who experience recurrent infections, and antibiotic treatment usually fails due to antibiotic resistance. Therefore, an infection can lead to severe illness and hospitalization if left untreated. A growing number of studies have demonstrated promising results for a variety of probiotic strains used to prevent or treat acute and recurrent infectious diseases, but additional standardized clinical research is needed.
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