In Vivo and In Vitro Effects of ATM/ATR Signaling Pathway on Proliferation, Apoptosis, and Radiosensitivity of Nasopharyngeal Carcinoma Cells

Replication Stress: A Review of Novel Targets to Enhance Radiosensitivity-From Bench to Clinic

DNA replication is a process fundamental in all living organisms in which deregulation, known as replication stress, often leads to genomic instability, a hallmark of cancer. Most malignant tumors sustain persistent proliferation and tolerate replication stress via increasing reliance to the replication stress response. So whilst replication stress induces genomic instability and tumorigenesis, the replication stress response exhibits a unique cancer-specific vulnerability that can be targeted to induce catastrophic cell proliferation. Radiation therapy, most used in cancer treatment, induces a plethora of DNA lesions that affect DNA integrity and, in-turn, DNA replication. Owing to radiation dose limitations for specific organs and tumor tissue resistance, the therapeutic window is narrow. Thus, a means to eliminate or reduce tumor radioresistance is urgently needed. Current research trends have highlighted the potential of combining replication stress regulators with radiation therapy to capitalize on the high replication stress of tumors. Here, we review the current body of evidence regarding the role of replication stress in tumor progression and discuss potential means of enhancing tumor radiosensitivity by targeting the replication stress response. We offer new insights into the possibility of combining radiation therapy with replication stress drugs for clinical use.

Allicin enhances the radiosensitivity of colorectal cancer cells via inhibition of NF-κB signaling pathway

Radioresistance is an important factor affecting the radiotherapy effect of colorectal cancer (CRC). Allicin is a versatile sulfur-containing organic compound extracted from garlic (Allium sativum L.), which has many pharmacological effects. However, the effect of allicin on the sensitivity of CRC radiotherapy has not been confirmed. The present study is to observe the radiosensitivity effects of allicin and to explore its mechanism in CRC radiotherapy. The proliferation inhibition effects of allicin combined with X-ray radiotherapy in HCT116 cells were measured by growth curve of cell and colony formation assays. The cell apoptosis was detected by Hoechst 33258 nucleus staining assay. The migration ability of cells was detected by Transwell chamber migration assay. The animal model of CRC was established in BALB/c mice via transplantation of CT26 cell, and the radiosensitization effect of allicin on CRC was detected in vivo. The mRNA expressions of NF-κB, IKKβ, and IκBα were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The protein expressions of NF-κB, p-NF-κB, IKKβ, p-IKKβ, IκBα, and p-IκBα were detected by western blotting. Our results showed that allicin improves the sensitivity of X-ray radiotherapy in CRC, and its mechanism may be associated with inhibition of NF-κB signaling pathway. These findings suggest that allicin may be used as a potential sensitizer for tumor radiotherapy in the clinic.

MiR-203a-3p regulates the biological behaviors of ovarian cancer cells through mediating the Akt/GSK-3β/Snail signaling pathway by targeting ATM

OBJECTIVE

To investigate whether miR-203a-3p can regulate the biological behaviors of ovarian cancer cells by targeting ATM to affect the Akt/GSK-3β/Snail signaling pathway.

METHODS

The expression levels of miR-203a-3p and ATM were detected by qRT-PCR, immunohistochemical staining and Western blotting in ovarian cancer tissues and adjacent normal tissues obtained from 152 subjects. A dual-luciferase reporter gene assay was performed to verify the relationship between miR-203a-3p and ATM. Human ovarian cancer cell lines (A2780 and SKOV3) were used to generate the Blank, miR-NC, miR-203a-3p mimic, Control siRNA, ATM siRNA, and miR-203a-3p inhibitor + ATM siRNA groups. The biological behaviors of ovarian cancer cells were evaluated by CCK-8, wound healing, and Transwell invasion assays, annexin V-FITC/PI staining and flow cytometry. The levels of Akt/GSK-3β/Snail pathway-related proteins were assessed by Western blotting.

RESULTS

Ovarian cancer tissues showed lower miR-203a-3p levels and higher ATM levels than adjacent normal tissues, both of which were associated with the FIGO stage, grade and prognosis of ovarian cancer. As confirmed by a dual-luciferase reporter gene assay, miR-203a-3p could target ATM. Furthermore, the miR-203a-3p mimic had multiple effects, including the inhibition of the proliferation, invasion and migration of A2780 and SKOV3 cells, the promotion of cell apoptosis, the arrest of the cell cycle at the G1 phase, and the blockage of the Akt/GSK-3β/Snail signaling pathway. ATM siRNA had similar effects on the biological behaviors of ovarian cancer cells, and these effects could be reversed by a miR-203a-3p inhibitor.

CONCLUSION

miR-203a-3p was capable of hindering proliferation, migration, and invasion and facilitating the apoptosis of ovarian cancer cells through its modulation of the Akt/GSK-3β/Snail signaling pathway by targeting ATM, and therefore it could serve as a potential therapeutic option for ovarian cancer.

The identification of key genes in nasopharyngeal carcinoma by bioinformatics analysis of high-throughput data

Nasopharyngeal carcinoma (NPC) is a common pattern of regional malignancy in the south of China, especially in Guangdong province. The development of computerized tomography (CT) technology and the improvement of radiotherapy scheme can improve the survival rate of NPC patients. However, the prevalence and recurrence rate of NPC are increasing every year. It is urgent for us to uncover the molecular mechanism of NPC. In this study, we used scientific information retrieval from the GEO (gene expression omnibus) database to download the GSE12452, which contained 41 samples, including 31 nasopharyngeal carcinoma samples and 10 control samples. With the help of GO (gene ontology) analysis, KEGG (kyoto encyclopedia of genes and genomes) analysis, PPI (protein-protein interaction) network model construction, and WGCNA (weighted gene co-expression network analysis), we found 6896 differentially expressed genes, which affected the biological processes included cell cycle process, DNA metabolic process, DNA repairing, immune response, cell activation, regulation of immune system process, inflammatory response. The 20 hub genes present in front of us are SYK, PIK3CG, FYN, ACACB, LRRK2, RIPK4, RAC2, PIK3CD, PTPRC, LCR, RAD51, MAD2L1, CDK1, PCNA, GMPS, CCNB1, GAPDH, CCNA2, RFC4, TOP2A. In the future, these are the areas where we need to focus on the molecular mechanism of NPC.

MicroRNA-185 inhibits cell proliferation while promoting apoptosis and autophagy through negative regulation of TGF-β1/mTOR axis and HOXC6 in nasopharyngeal carcinoma

OBJECTIVE

Accumulating studies have revealed that microRNAs (miRs) play a critical role in the development and progression of nasopharyngeal carcinoma (NPC), which is a disease with a remarkable racial and geographical distribution. In our study, through the alteration in the expression of microRNA-185 (miR-185) in NPC cells by microarray-based gene expression profiling, we subsequently evaluated its ability to influence NPC cells and associated mechanism.

METHODS

The expressions of miR-185 and HOXC6 in NPC and paracancerous tissues collected from patients with NPC were detected. The CNE-2 cells with the lowest miR-185 among the five NPC cell lines (CNE-1, CNE-2, HNE-1, HNE-2, and 5-8F) were selected and transfected with a series of mimic or inhibitor of miR-185, or shRNA-against HOXC6. The Kaplan-Meier method was used to analyze the survival of patients. Besides, the reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot analysis were used to determine the levels of related genes/proteins. By means of cell counting kit-8 (CCK-8) assay, transwell assay, flow cytometry, and AO staining, the influences miR-185 has on the processes associated with NPC, including cell proliferation, invasion, apoptosis and autophagy were evaluated.

RESULTS

NPC was observed to decrease miR-185 but increase HOXC6. Dual luciferase reporter gene assay demonstrated that HOXC6 is a target gene of miR-185. Increased mRNA and protein levels of Bax, caspase-3, LC3 and Beclin1 and reduced levels of HOXC6, TGF-β1, mTOR, Cyclin D1, PCNA, Bcl-2 were found by overexpression of miR-185. High expression of miR-185 and low expression of HOXC6 had longer survival time of NPC patients. Overexpressed miR-185 enhanced cell apoptosis and autophagy, and reduced cell proliferation and invasion, while miR-185 inhibitor was observed to have induced effects on the CNE-2 cells.

CONCLUSION

Overall, the data show that miR-185 could negatively target HOXC6 to suppress cell proliferation, promotes apoptosis and autophagy through inhibiting TGF-β1/mTOR axis in NPC. Thus, miR-185 is useful strategy for the treatment of NPC.

Downregulation of ribophorin II suppresses tumor growth, migration, and invasion of nasopharyngeal carcinoma

Background

It has been reported that ribophorin II (RPN2) expression is increased in many cancers, but the role of RPN2 in nasopharyngeal carcinoma (NPC) remains unclear.

Patients and methods

This study found that the expression of RPN2 is increased dramatically in NPC tissues of patients compared with that in the adjacent normal tissues. This study attempted at understanding the effect of siRNA-RPN2 treatment on the migration and invasion of NPC cell lines CNE2 and HNE1.

Results

RT-PCR and Western blotting showed that RPN2 was highly expressed in CNE2 and HNE1 cells. siRNA-RPN2 treatment significantly inhibited cell viability at 24 and 48 h compared with the control group. Results of the transwell assay showed that, compared to the control groups, migration and invasion of the cells treated with siRNA-RPN2 decreased markedly. In addition, compared to the control groups, caspase-3, caspase-9, and E-cadherin expression levels increased and MMP 2 expression decreased significantly in the siRNA-RPN2-treated group. Phosphorylation of AKT and PI3K was also inhibited after siRNA-RPN2 treatment.

Conclusion

siRNA-RPN2 can effectively inhibit the invasion and migration of human NPC cells via AKT/PI3K signaling. This can serve as a novel strategy for NPC treatment.