Activating PTEN by COX-2 inhibitors antagonizes radiation-induced AKT activation contributing to radiosensitization

Generation of a competing endogenous RNA network and validation of BNIP1 expression in the lung of irradiated mice

BACKGROUND

Radiation-induced lung injury (RILI) is a serious complication of radiation therapy, and it is mediated by long non-coding RNAs (lncRNAs).

STUDY DESIGN AND METHODS

Mouse lung tissues were examined using RNA-Seq and RNA-Seq libraries 72 h after the administration of 6 Gy of X-ray irradiation. The target mRNAs were functionally annotated and the target lncRNA-based miRNAs and target miRNA-based mRNAs were predicted after irradiation to establish the lncRNA-miRNA-mRNA ceRNA axis.

RESULTS

The analyses showed that relative to unirradiated controls, 323 mRNAs, 114 miRNAs, and 472 lncRNAs were significantly up-regulated following irradiation, whereas 1907 mRNAs, 77 miRNAs, and 1572 lncRNAs were significantly down-regulated following irradiation. Voltage-gated ion channels, trans-membrane receptor protein tyrosine kinases, and vascular endothelial growth factor have all been associated with dysregulated miRNA-mRNA relationships. KEGG pathway analysis of the dysregulated miRNA-mRNA targets revealed involvement in pathways associated with the hedgehog signaling pathway-fly, ErbB signaling, VEGF signaling, axon guidance, and focal adhesion. KEGG analysis of differentially expressed showed enrichment of mRNAs in primary immunodeficiency, the intestinal immune axis for IgA production, hematopoietic cell lineages, systemic lupus erythematosus, and Th1 and Th2 cell differentiation. Finally, the ceRNA network revealed that BNIP1 was a critical mRNA modulated by the most significant upregulation of lncRNA E230013L22Rik.

CONCLUSION

In summary, the lncRNA-miRNA-mRNA ceRNA axis of RILI was constructed following irradiation in a mouse model. RNA dysregulation in the early stage of RILI may lead to severe complications at a later stage, with BNIP1 contributing to radiation-induced cellular apoptosis in RILI.

Exploring the Pharmacological Mechanism of Radix Salvia Miltiorrhizae in the Treatment of Radiation Pneumonia by Using Network Pharmacology

Background

Radiation pneumonia (RP) is the most common complication of radiotherapy to the thorax and seriously affects the survival rate and quality of life of patients. Radix Salviae Miltiorrhizae (RSM) is an ancient Chinese medicine, whose main pharmacological effect is to promote blood circulation and remove stasis. A growing number of studies have proved that RSM has a good effect on RP. However, the underlying mechanism is still unclear and needs to be fully elucidated.

Methods

The effective components and predictive targets of RSM were analyzed by Traditional Chinese Medicine Systems Pharmacology (TCMSP) database, and the related targets of RP were predicted by GeneCards database. The common targets of the two targets mentioned above were analyzed by protein-protein interaction on the STRING website, GO and KEGG analysis on the DAVID website, visualization by CytoScape3.7.0, and screening for Hubber gene by cytoHubber plug-in.

Results

A search of the TCMSP database revealed that RSM contains 65 chemical constituents and 165 potential protein targets. A total of 2,162 protein targets were found to be associated with RP. The top 10 hub genes were obtained by MCC algorithm for 70 common genes, including TP53, CASP3, MAPK1, JUN, VEGFA, STAT3, PTGS2, IL6, AKT1, and FOS. By analyzing the Gene Ontology, The anti-radiation pneumonia effect of RSM is that it performs molecular functions (protein homodimerization activity) in the nucleus through three biological processes (positive regulation of transcription from RNA polymerase II promoter,Extrinsic apoptotic signaling pathway in absence of ligand and lipopolysaccharide-mediated signaling pathway). Through KEGG analysis, the mechanism of RSM treatment of radiation pneumonia may be through PI3K-Akt, HIF-1, TNF signaling pathways.

Conclusions

Through network pharmacology analysis, we found the possible target genes of RSM on RP and revealed the most likely signaling pathway, providing theoretical basis for further elucidating the potential mechanism of RSM on RP.

Celecoxib induces apoptosis through Akt inhibition in 5-fluorouracil-resistant gastric cancer cells

Gastric cancer is the fifth leading cause of cancer and a global public health problem. 5-Fluorouracil (5-FU) is the primary drug chosen for the treatment of advanced gastric cancer, but acquired cancer drug resistance limits its effectiveness and clinical use. Proliferation assays showed that a gastric carcinoma cell line, AGS and 5-FU-resistant AGS cells (AGS FR) treated with 3-100 μM 5-FU for 48 h or 72 h showed different sensitivities to 5-FU. Immunoblot assay demonstrated that AGS FR cells expressed more COX-2 and PGE₂-cognated receptor EP2 than AGS cells. AGS FR cells considerably produced PGE₂ than AGS upon stimulation with 5-FU. These results suggest that COX-2 expression is associated with 5-FU resistance. Unlike AGS FR cells, AGS cells showed increased levels of both cleaved caspase-3 and Bax following 5-FU treatment. Treatment of cells with the COX-2 selective inhibitor celecoxib induced cell death of AGS FR cells in a time- and concentration-dependent manner. FACS analysis showed that celecoxib at high doses caused apoptotic cell death, demonstrating a concentration-dependent increase in the cell populations undergoing early apoptosis and late apoptosis. This apoptotic induction was strongly supported by the expression profiles of apoptosis- and survival-associated proteins in response to celecoxib; pro-apoptotic cellular proteins increased while expressions of COX-2 and p-Akt were downregulated in a concentration-dependent manner. An increase in PTEN expression was accompanied with downregulation of p-Akt. Based on the data that downregulation of COX-2 was correlated with the concentrations of celecoxib, COX-2 may play a key role in celecoxib-induced cell death of AGS FR cells. Butaprost, the EP2 agonist, promoted proliferative activity of AGS FR cells in a concentration-dependent manner compared with AGS cells. In cells exposed to butaprost, expressions of COX-2 and p-Akt were increased in a concentration-dependent manner with concomitantly reduced PTEN levels. Taken together, 5-FU-resistance in gastric cancer is correlated with COX-2 expression, and therefore the selective inhibition of COX-2 leads to suppression of cell proliferation of AGS FR cells. Modulation of COX-2 expression and its catalytic activity may be a potential therapeutic strategy to overcome 5-FU-resistant gastric cancer.

miRNA as promising theragnostic biomarkers for predicting radioresistance in cancer: A systematic review and meta-analysis

Radioresistance remains as an obstacle in cancer treatment. This systematic review and meta-analysis aimed to evaluate the association between the expression of miRNAs and responses to radiotherapy and the prognosis of different tumors. In total, 77 miRNAs in 19 cancer types were studied, in which 24 miRNAs were upregulated and 58 miRNAs were downregulated in cancer patients. Five miRNAs were differentially expressed. Moreover, 75 miRNAs were found to be related to radioresistance, while 5 were observed to be related to radiosensitivity. The pooled HR and 95 % confidence interval for the combined studies was 1.135 (0.819-1.574; P-value = 0.4). The HR values of the subgroup analysis for miR-21 (HR = 2.344; 95 % CI: 1.927-2.850; P-value = 0.000), nasopharyngeal carcinoma (HR = 0.448; 95 % CI: 0.265-0.760; P = 0.003) and breast cancer (HR = 1.131; 95 % CI: 0.311-4.109; P = .85) were obtained. Our results highlighted that across the published literature, miRNAs can modulate tumor radioresistance or sensitivity by affecting radiation-related signaling pathways. It seems that miRNAs could be considered as a theragnostic biomarker to predict and monitor clinical response to radiotherapy. Thus, the prediction of radioresistance in malignant patients will improve radiotherapy outcomes and radiotherapeutic resistance.

Celecoxib and Afatinib synergistic enhance radiotherapy sensitivity on human non-small cell lung cancer A549 cells

PURPOSE

Radioresistance is highly correlated with radiotherapy failure in clinical cancer treatment. In the current study, we sought to examine the efficacy of Celecoxib and Afatinib co-treatment as radiosensitizers in the management of non-small cell lung cancer (NSCLC) A549 cells.

MATERIALS AND METHODS

Generally, A549 cells were cultured with the treatment of Celecoxib and/or Afatinib for 24 h. Then, the cells were exposed to irradiation at 2 Gy/min for 1 min. After the end of treatment, cell viability, clonogenic survival, apoptosis and Prostaglandin E2 (PGE2) Elisa assays were performed. Transcriptional levels of Cyclooxygenase-2 (COX-2) affected by Celecoxib and/or Afatinib were measured by RT-qPCR. Posttranscriptional level of epidermal growth factor receptor (EGFR)-related gene was measured by Western blotting analysis.

RESULTS

Here, we, for the first time, reported that the co-treatment of Celecoxib and Afatinib regulates the resistance of NSCLC A549 cells to radiation. The co-treatment of Celecoxib and Afatinib sensitized radiotherapy through the radiation-induced loss of cell viability and colony formation, as well as apoptosis. Mechanistically, Celecoxib and Afatinib-treated cells showed the inhibition of COX-2 and EGFR expression, which may be responsible for the A549 cells' increased resistance to radiation.

CONCLUSION

Our results suggested that Celecoxib and Afatinib regulate cell sensitivity to apoptosis, and thus modulate the resistance of NSCLC to radiation.

Cellular Stress Responses in Radiotherapy

Radiotherapy is one of the major cancer treatment strategies. Exposure to penetrating radiation causes cellular stress, directly or indirectly, due to the generation of reactive oxygen species, DNA damage, and subcellular organelle damage and autophagy. These radiation-induced damage responses cooperatively contribute to cancer cell death, but paradoxically, radiotherapy also causes the activation of damage-repair and survival signaling to alleviate radiation-induced cytotoxic effects in a small percentage of cancer cells, and these activations are responsible for tumor radio-resistance. The present study describes the molecular mechanisms responsible for radiation-induced cellular stress response and radioresistance, and the therapeutic approaches used to overcome radioresistance.

Decreased expression level and DNA-binding activity of specificity protein 1 via cyclooxygenase-2 inhibition antagonizes radiation resistance, cell migration and invasion in radiation-resistant lung cancer cells

Radiation is able to inhibit tumor growth, promote tumor cell apoptosis and prolong patient survival. However, radiation resistance remains a major impediment to radiotherapy. Local and metastatic recurrences following radiation are still large impediments to overall survival. Although cyclooxygenase-2 (COX-2) inhibitors may induce radiation sensitivity in cancer cells, the underlying mechanisms are not fully understood. The present study demonstrated high potential for cell proliferation, migration and invasion in radiation-resistant lung cancer cell lines. The present study observed the overexpression of specificity protein 1 (Sp1) in these cells, and the overexpression of Sp1 induced upregulation of matrix metalloproteinase (MMP)-2, MMP-9, B cell lymphoma-2, in addition to a high potential for radiation resistance, migration and invasion in these cells. The present study revealed that the COX-2 selective inhibitor, celecoxib, enhanced radiation sensitivity and inhibited migration and invasion in these cells by inhibiting the expression and DNA-binding activity of Sp1. Furthermore, celecoxib downregulated Sp1 by inhibiting c-Jun N-terminal kinase (JNK). Taken together, the present study demonstrated that Sp1 overexpression in radiation-resistant cancer cells and COX-2 inhibitors enhanced radiation sensitivity and inhibited the migration and invasion of cancer cells, at least partially, via inactivation of the JNK/Sp1 signaling pathway and a decrease in Sp1 DNA-binding activity.

Synergistic antitumor effects of the combined treatment with an HDAC6 inhibitor and a COX-2 inhibitor through activation of PTEN

Chemotherapy is one of the most effective non-surgical treatments for various types of tumor. Identifying different combinations of antitumor agents that can produce synergistic antitumor effects remains an important clinical strategy. In the present study, we showed that the combination of histone deacetylase 6 (HDAC6) inhibitor tubastatin A together with cyclooxygenase-2 (COX-2) inhibitor celecoxib resulted in synergistic antitumor effects in CAL 27 and SACC-83 cells. Treatment with celecoxib alone promoted the membrane translocation of phosphatase and tensin homolog (PTEN), indicating PTEN activation, and consequently led to protein kinase B (AKT) dephosphorylation (inactivation). Similarly, treatment with an HDAC6 inhibitor alone promoted PTEN membrane translocation and correspondingly dephosphorylated AKT. The combination of celecoxib and an HDAC6 inhibitor synergistically increased PTEN membrane translocation and inactivated AKT. Moreover, celecoxib enhanced the HDAC6 inhibitor-induced antitumor effects in PTEN-deficient U-87 MG cells that had been stably transfected with wild-type PTEN, but not in the same cell line stably transfected with mutant PTEN-K163R, which cannot be activated by HDAC6 inhibitors. In summary, the results indicated that the COX-2 inhibitor celecoxib enhanced the HDAC6 inhibitor-induced antitumor effects by activating the PTEN/AKT signaling pathway.

Activating AKT to inhibit JNK by troxerutin antagonizes radiation-induced PTEN activation

Radiotherapy is one of the most effective non-surgical treatments for many tumors. However, radiation damage remains a major negative consequence of radiotherapy. At present, radio-protective effect of troxerutin has been confirmed, but the mechanism of this radioprotection has not been elucidated. Here, this study showed that troxerutin protected thymus tissue of irradiated mice, and its radio-protective effect on thymocytes was significant in the range of 0.625-10μg/ml. Troxerutin significantly inhibited apoptosis of irradiated thymocytes at the concentration of 10μg/ml. Computer-aided drug design was used to investigate potential candidate targets for troxerutin, and an excellent correlation was identified between troxerutin and AKT (Pharm mapper and KEGG signal pathway). Troxerutin inhibited the activation of PTEN to stimulate AKT, which in turn prevented the activation of JNK to protect cells. Our results showed that troxerutin enhanced radioprotection at least partially by activating AKT to inhibit the activation of JNK.