Resibufogenin suppresses growth and metastasis through inducing caspase-1-dependent pyroptosis via ROS-mediated NF-κB suppression in non-small cell lung cancer.

The purpose of this study is to explore the antitumor properties of resibufogenin (RB) in non-small cell lung cancer (NSCLC) and elucidate its underlying mechanism. A549 and H520 cells were treated with various concentrations of RB with or without NLRP3 inhibitor (MCC950), caspase-1 inhibitor (VX765), or N-acetyl-l-cysteine (an ROS scavenger). Cell counting kit-8 and colony formation assays were conducted to determine cell viability. Cell invasion was detected by using the transwell assay. The release of lactate dehydrogenase (LDH) was determined by the LDH detection assay. The protein expression levels of related genes were measured by western blotting and immunohistochemistry. The reactive oxygen species (ROS) level was detected by using a 2,7-dichlorodihydrofluorescein diacetate ROS Assay Kit. The in vivo effects of RB were evaluated in a xenograft mouse model. RB treatment reduced cell viability and invasion in a dose-dependent manner. Furthermore, RB also enhanced pyroptosis levels in A549 and H520 cells, as indicated by the increased release of LDH and pyroptosis-related proteins. Interestingly, we also found that the antiproliferative and antimetastatic effects of RB were alleviated by the blockade of pyroptosis using NLRP3 inhibitor MCC950. Further study demonstrated that RB induced pyroptosis in a caspase-1-dependent manner, as evidenced by the finding that VX765 effectively reversed the effects of RB on A549 and H520 cells. We also found that RB could trigger caspase-1-dependent pyroptosis through ROS-mediated NF-κB suppression. In summary, our findings provide a potential antitumor agent and a novel insight into the mechanism of RB treatment of NSCLC.

miR-107 regulates cisplatin chemosensitivity of A549 non small cell lung cancer cell line by targeting cyclin dependent kinase 8.

Previous studies demonstrated that the acquired drug resistance of non-small cell lung cancer (NSCLC) was related to deregulation of miRNAs. However, the effects of miR-107 and the mechanism through which miR-107 affects the cisplatin chemoresistance in NSCLC have not been reported. TaqMan RT-PCR or Western blot assay was performed to detect the expression of mature miR-107 and cyclin dependent kinase 8 (CDK8) protein. The viabilities of treated cells were analyzed using MTT assay. We found that the expression level of miR-107 in A549 cells was significantly lower than that in normal human bronchial epithelial cells (0.45 ± 0.26 vs. 1.00 ± 0.29, P = 0.032). The MTT assay showed that the A549 cells transfected with miR-107 mimics were significantly more sensitive to the therapy of cisplatin than control cells. A549 cells transfected with miR-107 mimics showed a decreased CDK8 protein expression. Downregulation of CDK8 expression by siRNAs, A549 cells became more sensitive to the therapy of cisplatin. In addition, the enhanced growth-inhibitory effect by the miR-107 mimic transfection was enhanced after the addition of CDK8 siRNA. In conclusion, the present study provides the first evidence that miR-107 plays a key role in cisplatin resistance by targeting the CDK8 protein in NSCLC cell lines, suggesting that miR-107 can be used to predict a patient's response to chemotherapy as well as serve as a novel potential maker for NSCLC therapy.

microRNA­802 promotes lung carcinoma proliferation by targeting the tumor suppressor menin.

microRNAs play important roles in numerous biological processes, including tumorigenesis, by modulating critical gene transcripts. In the present study, the role of microRNA­802 (miR­802) in lung cancer was investigated. The results of the quantitative polymerase chain reaction revealed that expression levels of miR­802 were significantly upregulated in lung cancer tissues. In vitro experiments demonstrated that miR­802 promoted cell proliferation in A549, NCI­H358 and NCI­H1299 cells. Furthermore, it was indicated that miR­802 promoted the proliferation of lung carcinoma by targeting the tumor suppressor menin. Therefore, these results suggest a previously unknown miR­802/menin molecular network controlling lung carcinoma development.