PURPL Promotes M2 Macrophage Polarization in Lung Cancer by Regulating RBM4/xCT Signaling.

Lung cancer is the most common malignancy worldwide. Long non-coding RNA (lncRNA) p53 upregulated regulator of P53 levels (PURPL) is abnormally in various cancers. However, the reports on its roles in lung cancer are limited. The purpose of present study is to investigate the potentials of lncRNA PURPL in lung cancer. PURPL and mRNA expression was determined using real-time reverse transcriptase-polymerase chain reaction (RT-qPCR). The location of PURPL was detected using RNA fluorescence in situ hybridization (FISH) assay. Protein expression was detected using western blot. Cellular functions were determined using flow cytometry. The interaction between PURPL and RNA-binding motif 4 (RBM4) was confirmed using RNA immunoprecipitation (RIP) assay. PURPL was overexpressed in lung cancer cells and patients. Overexpressed PURPL promoted M2 macrophage polarization and suppressed ferroptosis. Additionally, PURPL maintained the mRNA stability of cystine glutamate reverse transporter (xCT) via regulating RBM4. xCT knockdown antagonized the effects of overexpressed PURPL and inhibited M2 macrophage polarization via inducing macrophage ferroptosis. PURPL/RBM4/xCT axis promoted M2 macrophage polarization in lung cancer. Therefore, PURPL may be a potential target of lung cancer.

KIAA1429-mediated RXFP1 attenuates non-small cell lung cancer tumorigenesis via N6-methyladenosine modification.

BACKGROUND: N6-methyladenosine (m6A) modification has been associated with non-small cell lung cancer (NSCLC) tumorigenesis. OBJECTIVES: This study aimed to determine the functions of Vir-like m6A methyltransferase-associated (KIAA1429) and relaxin family peptide receptor 1 (RXFP1) in NSCLC. METHODS: A quantitative real-time polymerase chain reaction was used to analyze the mRNA levels of KIAA1429 and RXFP1 in NSCLC. After silencing KIAA1429 or RXFP1 in NSCLC cells, changes in the malignant phenotypes of NSCLC cells were assessed using cell counting kit-8, colony formation, and transwell assays. Finally, the m6A modification of RXFP1 mediated by KIAA1429 was confirmed using luciferase, methylated RNA immunoprecipitation, and western blot assays. RESULTS: KIAA1429 and RXFP1 were upregulated and downregulated in NSCLC, respectively. Silencing of KIAA1429 attenuated the viability, migration, and invasion of NSCLC cells, whereas silencing of RXFP1 showed the opposite function in NSCLC cells. Moreover, RXFP1 expression was inhibited by KIAA1429 via m6A-modification. Therefore, silencing RXFP1 reversed the inhibitory effect of KIAA1429 knockdown in NSCLC cells. CONCLUSION: Our findings confirmed that the KIAA1429/RXFP1 axis promotes NSCLC tumorigenesis. This is the first study to reveal the inhibitory function of RXFP1 in NSCLC via KIAA1429-mediated m6A-modification. These findings may help identify new biomarkers for targeted NSCLC therapy.

α-Mangostin Suppresses Melanoma Growth, Migration, and Invasion and Potentiates the Anti-tumor Effect of Chemotherapy.

Purpose: Melanoma is a highly malignant tumor, which metastasizes and has poor prognosis in late-stage cancer patients. α-Mangostin possesses pharmacological properties, including antioxidant, anti-infective, and anticarcinogenic activities. We investigated α-Mangostin effect on melanoma growth, migration, and invasion and its possible molecular mechanism. Methods: Melanoma cells growth inhibition was determined by the colorimetric 4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay. Morphological changes of α-Mangostin-treated melanoma cells were evaluated by transmission electron microscopy and JC-1 staining. Cell apoptosis and cell cycle arrest were assessed by flow cytometry. The effect of α-Mangostin on tumor cells migration and invasion was observed by migration and invasion in vitro assay. Furthermore, the nude and C57BL/6 mouse subcutaneous melanoma models were used to evaluate the in vivo anti-tumor effect of α-Mangostin. Western blot and real time-PCR were performed to analyze the influence of α-Mangostin on some of the common signaling pathways in melanoma cell lines. Signaling pathways were further verified in dissected tumor tissues. Results: α-Mangostin inhibited in vitro melanoma cells proliferation, migration, and invasion of melanoma cells, induced cell cycle arrest in G0/G1 phase, and caused mitochondrial swelling and membrane depolarization, whereas it effectively suppressed melanoma growth in xenografted mice. In addition, α-Mangostin potentiated the in vitro and in vivo anti-tumor effects of cisplatin both in vitro and in vivo. Mechanistically, α-Mangostin down-regulated expression of RAS protein and mRNA, as well as phosphorylation of PI3K in A375, B16F10, M14 and SK-MEL-2 cells. MITF protein and mRNA were inhibited only in M14 cells. Conclusion: α-Mangostin suppresses melanoma cells growth, migration and invasion, and synergistically enhances the anti-tumor effect of chemotherapy, whose mechanism may be mediated through inhibiting Ras, PI3K and MITF.

Ferroptosis: A Novel Anti-tumor Action for Cisplatin.

PURPOSE: Ferroptosis is a new mode of regulated cell death, which is completely distinct from other cell death modes based on morphological, biochemical, and genetic criteria. This study evaluated the therapeutic role of ferroptosis in classic chemotherapy drugs, including the underlying mechanism. MATERIALS AND METHODS: Cell viabilitywas detected by using the methylthiazoltetrazlium dye uptake method. RNAiwas used to knockout iron-responsive element binding protein 2, and polymerase chain reaction, western blot was used to evaluate the efficiency. Intracellular reduced glutathione level and glutathione peroxidases activitywere determined by related assay kit. Intracellularreactive oxygen species levelswere determined by flowcytometry. Electron microscopywas used to observe ultrastructure changes in cell. RESULTS: Among five chemotherapeutic drugs screened in this study, cisplatin was found to be an inducer for both ferroptosis and apoptosis in A549 and HCT116 cells. The depletion of reduced glutathione caused by cisplatin and the inactivation of glutathione peroxidase played the vital role in the underlying mechanism. Besides, combination therapy of cisplatin and erastin showed significant synergistic effect on their anti-tumor activity. CONCLUSION: Ferroptosis had great potential to become a new approach in anti-tumor therapies and make up for some classic drugs, which open up a new way for their utility in clinic.

α-Mangostin, a Natural Agent, Enhances the Response of NRAS Mutant Melanoma to Retinoic Acid.

BACKGROUND The identification and use of novel compounds alone or in combination hold promise for the fight against NRAS mutant melanoma. MATERIAL AND METHODS We screened a kinase-specific inhibitor library through combining it with α-Mangostin in NRAS mutant melanoma cell line, and verified the enhancing effect of α-Mangostin through inhibition of the tumorigenesis pathway. RESULTS Within the kinase inhibitors, retinoic acid showed a significant synergistic effect with α-Mangostin. α-Mangostin also can reverse the drug resistance of retinoic acid in RARa siRNA-transduced sk-mel-2 cells. Colony assay, TUNEL staining, and the expressions of several apoptosis-related genes revealed that a-Mangostin enhanced the effect of retinoic acid-induced apoptosis. The combination treatment resulted in marked induction of ROS generation and inhibition of the AKT/S6 pathway. CONCLUSIONS These results indicate that the combination of these novel natural agents with retinoid acid may be clinically effective in NRAS mutant melanoma.

Lysyl oxidase mediates hypoxia-induced radioresistance in non-small cell lung cancer A549 cells.

Hypoxia-induced radioresistance has been well known as the main obstacle in cancer radiotherapy. Lysyl oxidase (LOX) was previously demonstrated to play an important role in hypoxia-induced biological behaviors, such as metastasis and angiogenesis, through hypoxia-inducible factor-1α (HIF-1α), which is an important contributing factor to radioresistance in tumor cells. However, how LOX plays a role in hypoxia-induced radioresistance has yet to be determined. Here, we found that LOX expression was in accordance with HIF-1α expression, and LOX expression at the mRNA and protein level, and enzymatic activity were remarkably upregulated in the hypoxic A549 cells, compared with normoxic A549 cells. Inhibition of LOX resulted in the reduction of the ability to repair double-stranded breaks (DSBs), promotion of apoptosis, relief of G2/M cycle arrest, and eventually reduction of hypoxia-induced radioresistance in the hypoxic A549 cells. This suggests that LOX may play an important role in hypoxia-induced radioresistance. Together, our results might suggest a novel potential therapeutic target in the management of non-small cell lung cancer (NSCLC).