MiR-101 sensitizes human nasopharyngeal carcinoma cells to radiation by targeting stathmin 1

GTSE1 promotes nasopharyngeal carcinoma proliferation and angiogenesis by upregulating STMN1

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a malignant tumor with poor survival rate. G2 and S phase-expressed-1 (GTSE1) takes part in the progression of diverse tumors as an oncogene, but its role and potential mechanism in NPC remain unknown.

METHODS

The GTSE1 expression was analyzed by western blot in NPC tissues and cells. Knock-down experiments were conducted to determine the function of GTSE1 in NPC by cell counting kit-8, the 5-ethynyl-2'-deoxyuridine (EdU) incorporation experiment, cell scratch wound-healing experiment, transwell assays, tube forming experiment and western blot. In addition, the in vivo role of GTSE1 was addressed in tumor-bearing mice.

RESULTS

The expression of was increased in NPC. Silencing of GTSE1 suppressed cell viability, the percent of EdU positive cells, and the number of invasion cells and tubes, but enhanced the scratch ratio in NPC cells. Mechanically, downregulation of GTSE1 decreased the expressions of FOXM1 and STMN1, which were restored with the upregulation of FOXM1. Increased expression of STMN1 reversed the effects of the GTSE1 silencing on proliferation, migration, invasion and angiogenesis of NPC cells. Furthermore, knockdown of GTSE1 repressed the tumor volume and tumor weight of xenografted mice.

CONCLUSION

GTSE1 was highly expressed in NPC, and silencing of GTSE1 ameliorated the malignant processes of NPC cells by upregulating STMN1, suggesting a possible therapeutical target for NPC.

Baicalein targets STMN1 to inhibit the progression of nasopharyngeal carcinoma via regulating the Wnt/β-catenin pathway

BACKGROUNDS

Nasopharyngeal carcinoma is a common malignancy in the head and neck. Baicalein has been reported to exert the anticancer effects on various cancers. In this study, our aim was to explore the function of baicalein in the development of nasopharyngeal carcinoma and further investigate the potential underlying mechanisms.

METHODS

Cell Counting Kit (CCK)-8 assay, EdU assay, sphere formation assay, flow cytometry, and transwell invasion assay were conducted to determine cell proliferation, stemness, apoptosis, and invasion, respectively. Western blot was performed to examine the protein levels of PCNA, MMP9, STMN1, β-catenin, and Wnt3A. The mRNA level of STMN1 was assessed using real-time quantitative polymerase chain reaction (RT-qPCR). Xenograft tumor model was carried out to evaluate the effects of baicalein on tumor growth in vivo. Immunohistochemistry (IHC) assay was used to detect the levels of PCNA, MMP9, and STMN1 in tumor tissues from mice.

RESULTS

Baicalein significantly induced cell apoptosis and impeded cell proliferation, invasion, and stemness of nasopharyngeal carcinoma cells. STMN1 was highly expressed in nasopharyngeal carcinoma, and baicalein could directly downregulate STMN1 expression. STMN1 knockdown hampered the progression of nasopharyngeal carcinoma cells. Moreover, the effects of baicalein on cell proliferation, stemness, invasion, and apoptosis in nasopharyngeal carcinoma cells were harbored by STMN1 overexpression. Baicalein regulated STMN1 to inhibit the activation of the Wnt/β-catenin pathway. SKL2001, an agonist of the Wnt/β-catenin pathway, could reverse the effects of STMN1 knockdown on the progression of nasopharyngeal carcinoma. In addition, baicalein markedly impeded tumor growth in vivo.

CONCLUSION

Baicalein regulated the STMN1/Wnt/β-catenin pathway to restrain the development of nasopharyngeal carcinoma.

MiRNA signatures in nasopharyngeal carcinoma: molecular mechanisms and therapeutic perspectives

Nasopharyngeal carcinoma (NPC) is a prevalent cancerous tumor that affects the head and neck region. Recent studies have provided compelling evidence indicating the significant involvement of microRNAs (miRNAs) in the development and progression of NPC. This review aims to present a comprehensive summary of the current knowledge regarding miRNA signatures in NPC, encompassing their expression patterns, molecular mechanisms, and potential therapeutic implications. Initially, the article outlines the aberrant expression of miRNAs in NPC and elucidates their roles in tumor initiation, invasion, and metastasis. Subsequently, the underlying molecular mechanisms of miRNA-mediated regulation of NPC-associated signaling pathways are discussed. Additionally, the review highlights the potential clinical applications of miRNAs as diagnostic and prognostic biomarkers, as well as their therapeutic potential in NPC treatment. In conclusion, this review underscores the critical involvement of miRNAs in NPC pathogenesis and underscores their promise as novel therapeutic targets for combating this devastating disease.

Precision medicine in nasopharyngeal carcinoma: comprehensive review of past, present, and future prospect

Nasopharyngeal carcinoma (NPC) is an aggressive malignancy with high propensity for lymphatic spread and distant metastasis. It is prominent as an endemic malignancy in Southern China and Southeast Asia regions. Studies on NPC pathogenesis mechanism in the past decades such as through Epstein Barr Virus (EBV) infection and oncogenic molecular aberrations have explored several potential targets for therapy and diagnosis. The EBV infection introduces oncoviral proteins that consequently hyperactivate many promitotic pathways and block cell-death inducers. EBV infection is so prevalent in NPC patients such that EBV serological tests were used to diagnose and screen NPC patients. On the other hand, as the downstream effectors of oncogenic mechanisms, the promitotic pathways can potentially be exploited therapeutically. With the apparent heterogeneity and distinct molecular aberrations of NPC tumor, the focus has turned into a more personalized treatment in NPC. Herein in this comprehensive review, we depict the current status of screening, diagnosis, treatment, and prevention in NPC. Subsequently, based on the limitations on those aspects, we look at their potential improvements in moving towards the path of precision medicine. The importance of recent advances on the key molecular aberration involved in pathogenesis of NPC for precision medicine progression has also been reported in the present review. Besides, the challenge and future outlook of NPC management will also be highlighted.

MicroRNA-101-3p inhibits nasopharyngeal carcinoma cell proliferation and cisplatin resistance through ZIC5 down-regulation by targeting SOX2

This study aims to explore the mechanism of microRNA (miR)-101-3p-mediated SOX2/ZIC5 axis in the progression of cisplatin resistance of nasopharyngeal carcinoma (NPC). ZIC5 expression was analyzed with a bioinformatics database and detected in NPC cell lines. Cisplatin-resistant cells (HNE-1/DDP and C666-1/DDP) were transfected with sh-ZIC5, sh-SOX2, sh-SOX2 + pcDNA3.1-ZIC5, or miR-101-3p Agomir + pcDNA3.1-SOX2. MiR-101-3p, SOX2, and ZIC5 expression was assessed after transfection, and cancer associated phenotypes were evaluated after cisplatin treatment. The potential relationships among miR-101-3p, SOX2, and ZIC5 were analyzed. A xenograft mouse model of NPC was established with HNE-1 cells stably transfected or not transfected with oe-ZIC5 and subjected to tail vein injection of miR-101-3p Agomir and intraperitoneal injection of cisplatin. Overexpression of ZIC5 was found in cisplatin-resistant NPC cells. Downregulating ZIC5 in NPC cells decreased cell viability, promoted apoptosis, and reduced cisplatin resistance. SOX2 had a binding site on ZIC5, and SOX2 promoted proliferation, migration, and cisplatin resistance and inhibited cell apoptosis by up-regulating ZIC5. Mechanistically, miR-101-3p was decreased in cisplatin-resistant NPC cells and negatively targeted SOX2. Overexpression of miR-101-3p inhibited tumor growth and cisplatin resistance in xenograft mouse model, which was reversed by ZIC5 overexpression. In conclusion, the miR-101-3p/SOX2/ZIC5 axis was implicated in cancer associated phenotypes and cisplatin resistance in NPC.

Elevated FAM134B expression induces radiation-sensitive in hepatocellular carcinoma

BACKGROUND

Previous studies have shown that Family with sequence similarity 134 member B (FAM134B) was involved in the occurrence and development of malignancy, however, the function and molecular mechanism of FAM134B in Hepatocellular Carcinoma (HCC) radiotherapy resistance remain unclear. Therefore, it may clinical effective to clarify the molecular mechanism and identify novel biomarker to overcome radiotherapy resistance in HCC.

METHODS

The protein and mRNA expression of FAM134B were determined using Real-time PCR and Western blot, respectively. IHC assay was performed to investigate the association between FAM134B expression and the clinicopathological characteristics of 132 HCC patients. Functional assays, such as in situ model, colon formation, FACS, and Tunel assay were used to determine the oncogenic role of FAM134B in human HCC progression. Furthermore, western blotting and luciferase assay were used to determine the mechanism of FAM134B promotes radiation-sensitive in HCC cells.

RESULTS

We noted that FAM134B was downregulated in HCC, which was correlated with the radiation resistance in patients with HCC. Overexpression of FAM134B contribute to radiation sensitive in HCC; however, inhibition of FAM134B confers HCC cell lines to radiation resistance both in vitro and in vivo. Moreover, we found that FAM134B interacts with FMS related receptor tyrosine kinase 3 (FLT3) and downregulation of FAM134B activated JAK/Stat3 signaling pathway. Importantly, pharmacological inhibition of JAK/Stat3 signaling pathway significantly counteracted downregulation of FAM134B-induced radiation resistance and enhanced radiation therapeutic efficacy in HCC.

CONCLUSIONS

Our findings suggest that FAM134B may be a potential therapeutic biomarker for the treatment of HCC patients with radiotherapy tolerance.

STNM1 in human cancers: role, function and potential therapy sensitizer

STMN1 belongs to the stathmin gene family, it encodes a cytoplasmic phosphorylated protein, stathmin1, which is commonly observed in vertebrate cells. STMN1 is a structural microtubule-associated protein (MAP) that binds to microtubule protein dimers rather than microtubules, with each STMN1 binding two microtubule protein dimers and preventing their aggregation, leading to microtubule instability. STMN1 expression is elevated in a number of malignancies, and inhibition of its expression can interfere with tumor cell division. Its expression can change the division of tumor cells, thereby arresting cell growth in the G2/M phase. Moreover, STMN1 expression affects tumor cell sensitivity to anti-microtubule drug analogs, including vincristine and paclitaxel. The research on MAPs is limited, and new insights on the mechanism of STMN1 in different cancers are emerging. The effective application of STMN1 in cancer prognosis and treatment requires further understanding of this protein. Here, we summarize the general characteristics of STMN1 and outline how STMN1 plays a role in cancer development, targeting multiple signaling networks and acting as a downstream target for multiple microRNAs, circRNAs, and lincRNAs. We also summarize recent findings on the function role of STMN1 in tumor resistance and as a therapeutic target for cancer.

The role of microRNA-induced apoptosis in diverse radioresistant cancers

Resistance to cancer radiotherapy is one of the biggest concerns for success in treating and preventing recurrent disease. Malignant tumors may develop when they block genetic mutations associated with apoptosis or abnormal expression of apoptosis; Tumor treatment may induce the expression of apoptosis-related genes to promote tumor cell apoptosis. MicroRNAs have been shown to contribute to forecasting prognosis, distinguishing between cancer subtypes, and affecting treatment outcomes in cancer. Constraining these miRNAs may be an attractive treatment strategy to help overcome radiation resistance. The delivery of these future treatments is still challenging due to the excess downstream targets that each miRNA can control. Understanding the role of miRNAs brings us one step closer to attaining patient treatment and improving patient outcomes. This review summarized the current information on the role of microRNA-induced apoptosis in determining the radiosensitivity of various cancers.

Autophagy as a self-digestion signal in human cancers: Regulation by microRNAs in affecting carcinogenesis and therapy response

Autophagy is defined as a "self-digestion" signal, and it is a cell death mechanism its primary function is degrading toxic agents and aged organelles to ensure homeostasis in cells. The basic leve ls of autophagy are found in cells, and when its levels exceed to standard threshold, cell death induction is observed. Autophagy dysregulation in cancer has been well-documented, and regulation of this pathway by epigenetic factors, especially microRNAs (miRNAs), is interesting and noteworthy. miRNAs are considered short endogenous RNAs that do not encode functional proteins, and they are essential regulators of cell death pathways such as apoptosis, necroptosis, and autophagy. Accumulating data has revealed miRNA dysregulation (upregulation or downregulation) during tumor progression, and their therapeutic manipulation provides new insight into cancer therapy. miRNA/autophagy axis in human cancers has been investigated an exciting point is the dual function of both autophagy and miRNAs as oncogenic and onco-suppressor factors. The stimulation of pro-survival autophagy by miRNAs can increase the survival rate of tumor cells and mediates cancer metastasis via EMT inductionFurthermore, pro-death autophagy induction by miRNAs has a negative impact on the viability of tumor cells and decreases their survival rate. The miRNA/autophagy axis functions beyond regulating the growth and invasion of tumor cells, and they can also affect drug resistance and radio-resistance. These subjects are covered in the current review regarding the new updates provided by recent experiments.

MiR-101: An Important Regulator of Gene Expression and Tumor Ecosystem

MiRNAs are small single-stranded non-coding RNAs. MiRNA contributes to the transcriptional and post-transcriptional regulation of mRNA in different cell types, including mRNA transcription inhibition and mRNA decay and phenotypes via the effect of several essential oncogenic processes and tumor microenvironment. MiR-101 is a highly conserved miRNA that was found to alter the expression in various human cancers. MiR-101 has been reported to have tumor oncogenic and suppressive effects to regulate tumorigenesis and tumor progression. In this review, we summarize the new findings about the roles of miR-101 in cancers and the underlying mechanisms of targeting genes degradation and microenvironment regulation, which will improve biological understanding and design of novel therapeutics.

A new biomarker to enhance the radiosensitivity of hepatocellular cancer: miRNAs

Aims: This review summarizes findings regarding miRNAs that modulate radiation in hepatocellular carcinoma (HCC) and evaluates their potential clinical therapeutic uses. Materials & methods: We searched the relevant English-language medical databases for papers on miRNAs and radiation therapy for tumors to identify miRNAs that are linked with radiosensitivity and radioresistance, focusing on those associated with HCC radiation. Results: There were 88 papers assessed for miRNAs associated with tumor radiation, 56 of which dealt with radiosensitization, 21 with radioresistance and 11 with radiosensitization for HCC. Conclusion: Further work in this area would enable future evaluation of radiation responses and the potential use of miRNAs as therapeutic agents in HCC patients.

Radio-Susceptibility of Nasopharyngeal Carcinoma: Focus on Epstein- Barr Virus, MicroRNAs, Long Non-Coding RNAs and Circular RNAs

Nasopharyngeal carcinoma (NPC) is a type of head and neck cancer. As a neoplastic disorder, NPC is a highly malignant squamous cell carcinoma that is derived from the nasopharyngeal epithelium. NPC is radiosensitive; radiotherapy or radiotherapy combining with chemotherapy are the main treatment strategies. However, both modalities are usually accompanied by complications and acquired resistance to radiotherapy is a significant impediment to effective NPC therapy. Therefore, there is an urgent need to discover effective radio-sensitization and radio-resistance biomarkers for NPC. Recent studies have shown that Epstein-Barr virus (EBV)-encoded products, microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), which share several common signaling pathways, can function in radio-related NPC cells or tissues. Understanding these interconnected regulatory networks will reveal the details of NPC radiation sensitivity and resistance. In this review, we discuss and summarize the specific molecular mechanisms of NPC radio-sensitization and radio-resistance, focusing on EBV-encoded products, miRNAs, lncRNAs and circRNAs. This will provide a foundation for the discovery of more accurate, effective and specific markers related to NPC radiotherapy. EBVencoded products, miRNAs, lncRNAs and circRNAs have emerged as crucial molecules mediating the radio-susceptibility of NPC. This understanding will improve the clinical application of markers and inform the development of novel therapeutics for NPC.

CircRNA ZNF609 promotes angiogenesis in nasopharyngeal carcinoma by regulating miR-145/STMN1 axis

Nasopharyngeal carcinoma (NPC) is the most common type of human malignant tumor in the head and neck, and tumor angiogenesis is essential for its development. Here, we showed that the circRNA ZNF609/microRNA (miR)-145/Stathmin 1 (STMN1) axis regulated angiogenesis in NPC.Circ-ZNF609, miR-145, and STMN1 expression in NPC cells and NPC samples were examined using qRT-PCR. The protein levels of STMN1, VEGFR1, and VEGFR2 were evaluated using western blotting. VEGF level was determined by ELISA. The proliferation of NPC cells and HUVECs was examined using a CCK-8 assay. Transwell assays and wound-healing assays were applied to assess the migration of NPC cells and HUVECs, respectively. Angiogenesis of HUVECs was evaluated by an angiogenesis assay. In addition, a dual-luciferase reporter assay and RNA pull-down assays were employed to verify the binding relationship between circ-ZNF609 and miR-145 as well as between miR-145 and STMN1. Here, we showed that circ-ZNF609 and STMN1 expression was increased, while miR-145 expression was decreased in NPC cells and NPC samples. Circ-ZNF609 may negatively regulate miR-145 expression by acting as a ceRNA. Silencing circ-ZNF609 suppressed cell proliferation, migration, and angiogenesis in NPC, while knockdown of miR-145 reversed these effects. In addition, we found that STMN1 was the downstream target of miR-145. MiR-145 overexpression suppressed cell proliferation, migration, and angiogenesis in NPC, which was abolished by STMN1 overexpression. Our data suggested that circ-ZNF609 promotes cell proliferation, migration, and angiogenesis in NPC by upregulating the expression of STMN1 by sponging miR-145 in NPC.

Cancer-associated fibroblasts promote the survival of irradiated nasopharyngeal carcinoma cells via the NF-κB pathway

Background

Irradiation has emerged as a valid tool for nasopharyngeal carcinoma (NPC) in situ treatment; however, NPC derived from tissues treated with irradiation is a main cause cancer-related death. The purpose of this study is to uncover the underlying mechanism regarding tumor growth after irradiation and provided potential therapeutic strategy.

Methods

Fibroblasts were extracted from fresh NPC tissue and normal nasopharyngeal mucosa. Immunohistochemistry was conducted to measure the expression of α-SMA and FAP. Cytokines were detected by protein array chip and identified by real-time PCR. CCK-8 assay was used to detect cell proliferation. Radiation-resistant (IRR) 5-8F cell line was established and colony assay was performed to evaluate tumor cell growth after irradiation. Signaling pathways were acquired via gene set enrichment analysis (GSEA). Comet assay and γ-H2AX foci assay were used to measure DNA damage level. Protein expression was detected by western blot assay. In vivo experiment was performed subcutaneously.

Results

We found that radiation-resistant NPC tissues were constantly infiltrated with a greater number of cancer-associated fibroblasts (CAFs) compared to radiosensitive NPC tissues. Further research revealed that CAFs induced the formation of radioresistance and promoted NPC cell survival following irradiation via the IL-8/NF-κB pathway to reduce irradiation-induced DNA damage. Treatment with Tranilast, a CAF inhibitor, restricted the survival of CAF-induced NPC cells and attenuated the of radioresistance properties.

Conclusions

Together, these data demonstrate that CAFs can promote the survival of irradiated NPC cells via the NF-κB pathway and induce radioresistance that can be interrupted by Tranilast, suggesting the potential value of Tranilast in sensitizing NPC cells to irradiation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01878-x.

Role of Non-coding RNAs on the Radiotherapy Sensitivity and Resistance of Head and Neck Cancer: From Basic Research to Clinical Application

Head and neck cancers (HNCs) rank as the sixth common and the seventh leading cause of cancer-related death worldwide, with an estimated incidence of 600,000 cases and 40-50% mortality rate every year. Radiotherapy is a common local therapeutic modality for HNC mainly through the function of ionizing radiation, with approximately 60% of patients treated with radiotherapy or chemoradiotherapy. Although radiotherapy is more advanced and widely used in clinical practice, the 5-year overall survival rates of locally advanced HNCs are still less than 40%. HNC cell resistance to radiotherapy remains one of the major challenges to improve the overall survival in HNC patients. Non-coding RNAs (ncRNAs) are newly discovered functional small RNA molecules that are different from messenger RNAs, which can be translated into a protein. Many previous studies have reported the dysregulation and function of ncRNAs in HNC. Importantly, researchers reported that several ncRNAs were also dysregulated in radiotherapy-sensitive or radiotherapy-resistant HNC tissues compared with the normal cancer tissues. They found that ectopically elevating or knocking down expression of some ncRNAs could significantly influence the response of HNC cancer cells to radiotherapy, indicating that ncRNAs could regulate the sensitivity of cancer cells to radiotherapy. The implying mechanism for ncRNAs in regulating radiotherapy sensitivity may be due to its roles on affecting DNA damage sensation, inducing cell cycle arrest, regulating DNA damage repair, modulating cell apoptosis, etc. Additionally, clinical studies reported that in situ ncRNA expression in HNC tissues may predict the response of radiotherapy, and circulating ncRNA from body liquid serves as minimally invasive therapy-responsive and prognostic biomarkers in HNC. In this review, we aimed to summarize the current function and mechanism of ncRNAs in regulating the sensitivity of HNC cancer cells to radiotherapy and comprehensively described the state of the art on the role of ncRNAs in the prognosis prediction, therapy monitoring, and prediction of response to radiotherapy in HNC.

The Emerging Roles of Autophagy-Related MicroRNAs in Cancer

Autophagy is a conserved catabolic process involving the degradation and recycling of damaged biomacromolecules or organelles through lysosomal-dependent pathways and plays a crucial role in maintaining cell homeostasis. Consequently, abnormal autophagy is associated with multiple diseases, such as infectious diseases, neurodegenerative diseases and cancer. Currently, autophagy is considered to be a dual regulator in cancer, functioning as a suppressor in the early stage while supporting the growth and metastasis of cancer cells in the later stage and may also produce therapeutic resistance. MicroRNAs (miRNAs) are small, non-coding RNA molecules that regulate gene expression at the post-transcriptional level by silencing targeted mRNA. MiRNAs have great regulatory potential for several fundamental biological processes, including autophagy. In recent years, an increasing number of studies have linked miRNA dysfunction to the growth, metabolism, migration, metastasis, and responses of cancer cells to therapy. Therefore, the study of autophagy-related miRNAs in cancer will provide insights into cancer biology and lead to the development of novel anti-cancer strategies. In the present review, we summarise the current knowledge of miRNA dysregulation during autophagy in cancer, focusing on the relationship between autophagy and miRNAs, and discuss their involvement in cancer biology and cancer treatment.

Inhibition of cell proliferation and radioresistance by miR-383-5p through targeting RNA binding protein motif (RBM3) in nasopharyngeal carcinoma

Background

RNA binding protein motif (RBM3) is associated with radioresistance in nasopharyngeal carcinoma (NPC), and miR-383-5p was predicted to target the 3'-untranslated region (3'UTR) of RBM3 messenger RNA (mRNA). Our study aimed to investigate the role and the mechanisms of miR-383-5p targeting RBM3 in NPC cell proliferation and radioresistance (RR).

Methods

The expression of miR-383-5p was detected by Real-time quantitative PCR (qRT-PCR) between RS (Radiosensitivity) and RR (Radioresistance) NPC patient- tissue specimens and cell lines. Cell Counting Kit-8 (CCK-8) and Clonogenic survival assay were applied to analyze the effect of miR-383-5p on NPC cell proliferation and radioresistance. Possible downstream target of miR-383-5p in NPC cells, RBM3was evaluated by luciferase assay and qRT-PCR. miR-383-5p inhibited NPC cell proliferation and radioresistance through RBM3 by rescue experiments. The effect of miR-383-5p on radiation-induced apoptosis was explored through Flow cytometric analysis and Western blotting. Western blotting was analyzed the molecular of RBM3-mediated Jun N-terminal kinase (JNK) and extracellular signal-related kinase (ERK) signaling pathways

Results

The expression of miR-383-5p was decreased in radioresistant NPC tissues and cells. miR-383-5p inhibited cell proliferation and radioresistance in CNE1/IR cells. We also observed that therapeutic administration of a miR-383-5p agomir dramatically sensitized NPC xenografts to radiation in a mouse model. Conversely, in the same xenograft model, administration of a miR-383-5p antagomir dramatically increased NPC resistance to radiation. miR-383-5p targeted the 3'UTR of RBM3. miR-383-5p inhibited NPC cell proliferation and radioresistance through RBM3. Finally, we found that miR-383-5p increased radiation-induced apoptosis, activated JNK signaling, and inhibited ERK signaling.

Conclusions

Our study revealed that miR-383-5p targeted the 3'UTR of RBM3 and contributed to the efficacy of NPC radiation therapy by altering the RBM3-mediated JNK and ERK signaling pathways.

Emerging role of non-coding RNAs in response of cancer cells to radiotherapy

Radiotherapy is an effective method for treatment of a large proportion of human cancers. Yet, the efficacy of this method is precluded by the induction of radioresistance in tumor cells and the radiation-associated injury of normal cells surrounding the field of radiation. These restrictions necessitate the introduction of modalities for either radiosensitization of cancer cells or protection of normal cells against adverse effects of radiation. Non-coding RNAs (ncRNAs) have essential roles in the determination of radiosensitivity. Moreover, ncRNAs can modulate radiation-induced side effects in normal cells. Several microRNAs (miRNAs) such as miR-620, miR-21 and miR-96-5p confer radioresistance, while other miRNAs including miR-340/ 429 confer radiosensitivity. The expression levels of a number of miRNAs are associated with radiation-induced complications such as lung fibrosis or oral mucositis. The expression patterns of several long non-coding RNAs (lncRNAs) such as MALAT1, LINC00630, HOTAIR, UCA1 and TINCR are associated with response to radiotherapy. Taken together, lncRNAs and miRNAs contribute both in modulation of response of cancer cells to radiotherapy and in protection of normal cells from the associated side effects. The current review provides an overview of the roles of these transcripts in these aspects.

Advances in targeted therapy mainly based on signal pathways for nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant epithelial carcinoma of the head and neck region which mainly distributes in southern China and Southeast Asia and has a crucial association with the Epstein-Barr virus. Based on epidemiological data, both incidence and mortality of NPC have significantly declined in recent decades grounded on the improvement of living standard and medical level in an endemic region, in particular, with the clinical use of individualized chemotherapy and intensity-modulated radiotherapy (IMRT) which profoundly contributes to the cure rate of NPC patients. To tackle the challenges including local recurrence and distant metastasis in the current NPC treatment, we discussed the implication of using targeted therapy against critical molecules in various signal pathways, and how they synergize with chemoradiotherapy in the NPC treatment. Combination treatment including targeted therapy and IMRT or concurrent chemoradiotherapy is presumably to be future options, which may reduce radiation or chemotherapy toxicities and open new avenues for the improvement of the expected functional outcome for patients with advanced NPC.

Development and Validation of a Prognostic Nomogram Based on Residual Tumor in Patients With Nondisseminated Nasopharyngeal Carcinoma

Objectives:

To investigate the prognostic value of residual tumor based on Magnetic resonance imaging(MRI) and establish an effective prognostic nomogram model referring to clinical,pathological and other related factors for predicting prognosis in nasopharyngeal carcinoma.

Methods:

Overall, 538 patients with non-metastatic, histologically-confirmed nasopharyngeal carcinoma were retrospectively examined. Data from 397 patients were used for the construction and validation of a nomogram based on the presence of residual tumor. A concordance index (C-index) was employed to assess the predictive accuracy and discriminative ability of the nomogram.

Results:

The 3-year survival rates in the non-residual and residual tumor cohorts were as follows: progression-free survival, 73.4% vs. 61.0%, P = 0.009; locoregional recurrence-free survival, 81.9% vs. 72.0%, P = 0.02; and distant metastasis-free survival, 80.7% vs. 73.5%, P = 0.11. Nine significant factors were included in the nomogram model. The calibration curve for the probability of progression-free survival showed that the nomogram-based predictive values had good concordance with the actual observations.

Conclusion:

The results showed that the patients in the residual tumor cohorts had a worse prognosis.The proposed nomogram may predict the prognosis and guide clinical decision-making concerning local residual tumors in nasopharyngeal carcinoma patients. Patients with a high risk of progression require more timely and aggressive treatment.

Non-Coding RNAs in Cancer Radiosensitivity: MicroRNAs and lncRNAs as Regulators of Radiation-Induced Signaling Pathways

Radiotherapy is a cancer treatment that applies high doses of ionizing radiation to induce cell death, mainly by triggering DNA double-strand breaks. The outcome of radiotherapy greatly depends on radiosensitivity of cancer cells, which is determined by multiple proteins and cellular processes. In this review, we summarize current knowledge on the role of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), in determining the response to radiation. Non-coding RNAs modulate ionizing radiation response by targeting key signaling pathways, including DNA damage repair, apoptosis, glycolysis, cell cycle arrest, and autophagy. Additionally, we indicate miRNAs and lncRNAs that upon overexpression or inhibition alter cellular radiosensitivity. Current data indicate the potential of using specific non-coding RNAs as modulators of cellular radiosensitivity to improve outcome of radiotherapy.

MicroRNAs as major regulators of the autophagy pathway

Autophagy is a cellular stress response mechanism activation of which leads to degradation of cellular components, including proteins as well as damaged organelles in lysosomes. Defects in autophagy mechanisms were associated with several pathologies (e.g. cancer, neurodegenerative diseases, and rare genetic diseases). Therefore, autophagy regulation is under strict control. Transcriptional and post-translational mechanisms that control autophagy in cells and organisms studied in detail. Recent studies introduced non-coding small RNAs, and especially microRNAs (miRNAs) in the post-translational orchestration of the autophagic activity. In this review article, we analyzed in detail the current status of autophagy-miRNA connections. Comprehensive documentation of miRNAs that were directly involved in autophagy regulation resulted in the emergence of common themes and concepts governing these complex and intricate interactions. Hence, a better and systematic understanding of these interactions reveals a central role for miRNAs in the regulation of autophagy.

CircCTDP1 promotes nasopharyngeal carcinoma progression via a microRNA‑320b/HOXA10/TGFβ2 pathway

Circular RNAs have been reported to play a vital role in the development and progression of various types of cancer. However, the underlying molecular role of circular RNA CTDP1 (circCTDP1) in the tumorigenesis of nasopharyngeal carcinoma (NPC) remains unknown. In the present study, circCTDP1 expression was found to be markedly upregulated in NPC tissues and cell lines (SUNE1, SUNE2 and 6-10B cell lines). Knockdown of circCTDP1 resulted in inhibition of proliferation, migration and invasion, and promoted apoptosis of NPC cells. Moreover, circCTDP1 directly interacted with microRNA (miR)-320b based on bioinformatics prediction and dual luciferase assay, and transfection with an miR-320b inhibitor reversed the effects of circCTDP1 knockdown on NPC cells. Furthermore, circCTDP1/miR-320b promoted NPC progression by regulating the expression of homeobox A10 (HOXA10). In addition, it was demonstrated that HOXA10 may exert its oncogenic role in NPC by regulating the expression of transforming growth factor β2 (TGFβ2). Taken together, these results revealed a novel regulatory mechanism, which may provide an improved understanding of NPC tumorigenesis and be useful in the development of potential targets for NPC therapy.

MicroRNA-101 inhibits cell migration and invasion in bladder cancer via targeting FZD4

Dysfunction of microRNAs (miRs) has been implicated in the development and progression of various human cancers. Our previous study demonstrated that miR-101 inhibited bladder cancer cell proliferation and invasion through inhibition of c-FOS expression. As an miR generally has many targets, other targets of miR-101 may also serve important roles in bladder cancer progression. Reverse transcription-quantitative polymerase chain reaction and western blot analyses were used to examine mRNA and protein expression, respectively. Wound healing and Transwell assays were conducted to study cell migration and invasion, respectively. The luciferase reporter gene assay was performed to verify one of the targets of miR-101. The data in the present study indicate that the expression of miR-101 is significantly reduced in bladder cancer tissues compared with that in adjacent non-tumour tissues. In addition, miR-101 expression is also downregulated in bladder cancer cell lines compared with that in normal bladder epithelial cells. Furthermore, low expression of miR-101 was significantly associated with tumour metastasis, advanced clinical stage, and poor prognosis in bladder cancer. Frizzled class receptor 4 (FZD4) was identified as a novel target of miR-101 in bladder cancer cells. The expression of FZD4 was significantly upregulated in bladder cancer tissues and cell lines. Both miR-101 overexpression and FZD4 inhibition caused a significant reduction of the migration and invasion of bladder cancer cells, whereas overexpression of FZD4 reversed the suppressive effects of miR-101 on bladder cancer cell migration and invasion. In conclusion, it was demonstrated that miR-101 downregulation is associated with bladder cancer progression and that miR-101 can inhibit bladder cancer cell migration and invasion via directly targeting FZD4. The present study expands the understanding of the molecular mechanisms underlying bladder cancer progression.

Autophagy-regulating microRNAs: potential targets for improving radiotherapy

BACKGROUND

Radiotherapy (RT) is one of the most important therapeutic strategies against cancer. However, resistance of cancer cells to radiation remains a major challenge for RT. Thus, novel strategies to overcome cancer cell radioresistance are urgent. Macroautophagy (hereafter referred to as autophagy) is a biological process by which damaged cell components can be removed and accordingly represent a cytoprotective mechanism. Because radiation-induced autophagy is associated with either cell death or radioresistance of cancer cells, a deeper understanding of the autophagy mechanism triggered by radiation will expedite a development of strategies improving the efficacy of RT. MicroRNAs (miRNAs) are involved in many biological processes. Mounting evidence indicates that many miRNAs are involved in regulation of the autophagic process induced by radiation insult, but the underlying mechanisms remain obscure. Therefore, a deep understanding of the mechanisms of miRNAs in regulating autophagy and radioresistance will provide a new perspective for RT against cancer.

METHODS

We summarized the recent pertinent literature from various electronic databases, including PubMed. We reviewed the radiation-induced autophagy response and its association of the role, function and regulation of miRNAs, and discussed the feasibility of targeting autophagy-related miRNAs to improve the efficacy of RT.

CONCLUSION

The beneficial or harmful effect of autophagy may depend on the types of cancer and stress. The cytoprotective role of autophagy plays a dominant role in cancer RT. For most tumor cells, reducing radiation-induced autophagy can improve the efficacy of RT. MiRNAs have been confirmed to take part in the autophagy regulatory network of cancer RT, the autophagy-regulating miRNAs therefore could be developed as potential targets for improving RT.

Time-course differential lncRNA and mRNA expressions in radioresistant hypopharyngeal cancer cells

Radioresistance remains a major problem in the treatment of patients with hypopharyngeal squamous cell carcinoma (HSCC). Long noncoding RNAs (lncRNAs) have important roles in the development, invasion, and metastasis of various tumors, including HSCC, but little is known about the role of lncRNAs in cancer radioresistance. The aim of this study was to identify radioresistance-related lncRNAs and mRNAs in radioresistant (RS) hypopharyngeal cancer subclone RS-FaDu cells. In this study, we performed microarray analysis to find the differences in time-course lncRNA and mRNA expression profiles between RS-FaDu and parent FaDu cells after 4 Gy radiation therapy, whose reliability was confirmed by validation experiment. Among these consistently dysregulated lncRNAs, we found that some lncRNAs (e.g., TCONS_00018436) might control resistance of HSCC cells to radiation. Furthermore, our bioinformatics analyses from mRNA/lncRNA microarray data showed that certain lncRNAs or mRNAs potentially are involved in radioresistance of HSCC. Our results from this study laid the foundation for further investigating the roles of these lncRNAs and mRNAs as promising candidates in the occurrence and development of HSCC radioresistance.

Knockout of the placenta specific 8 gene radiosensitizes nasopharyngeal carcinoma cells by activating the PI3K/AKT/GSK3β pathway

The present study investigated the radiosensitizing effect of placenta specific 8 (PLAC8) in nasopharyngeal carcinoma (NPC) cells. A PLAC8-knockout CNE2 cell line was constructed using the CRISPR/Cas9 system. The CCK-8 assay demonstrated knockout of PLAC8 significantly reduced cell proliferation and cell survival after irradiation compared to both control cells and non-irradiated PLAC8-knockout cells. The clonogenic assay showed knockout of PLAC8 enhanced the radiosensitivity of NPC cells. Flow cytometry revealed knockout of PLAC8 increased apoptosis and G2/M phase arrest after irradiation. Western blotting demonstrated knockout of PLAC8 was associated with increased levels of γHA2X, a higher BAX:BCL-2 ratio, and increased levels of phosphorylated-Akt and phosphorylated-GSK-3β. Overall, this study indicates PLAC8 contributes to radioresistance in NPC by inhibiting the PI3K/AKT/GSK3β pathway.

miR-101 targeting ZFX suppresses tumor proliferation and metastasis by regulating the MAPK/Erk and Smad pathways in gallbladder carcinoma

Gallbladder cancer (GBC), the most common malignancy of the bile duct, is highly aggressive and has an extremely poor prognosis, which is a result of early metastasis. As it is regulated being at multiple levels, the metastatic cascade in GBC is complex. Recent evidence suggests that microRNAs (miRNAs) are involved in cancer metastasis and are promising therapeutic targets. In this study, miR-101 was significantly downregulated in tumor tissues, particularly in metastatic tissues. In GBC patients, low miR-101 expression was correlated with tumor size, tumor invasion, lymph node metastasis, TNM stage, and poor survival. Moreover, miR-101 was an independent prognostic marker for GBC. Additionally, miR-101 inhibited GBC cell proliferation, migration, invasion, and TGF-β-induced epithelial-mesenchymal transition (EMT) in vitro and in vivo. Mechanistically, the gene encoding the zinc finger protein X-linked (ZFX) was identified as a direct target of miR-101. More importantly, miR-101 significantly reduced activation of the MAPK/Erk and Smad signaling pathways, resulting in inhibition of TGF-β-mediated induction of EMT. Altogether, our findings demonstrate a novel mechanism by which miR-101 attenuates the EMT and metastasis in GBC cells and suggest that miR-101 can serve as a potential biomarker and therapeutic target for GBC management.

The prognostic value of decreased miR-101 in various cancers: a meta-analysis of 12 studies

BACKGROUND

A consensus regarding the prognostic value of decreased miR-101 in human cancers has not been reached. This study aimed to comprehensively investigate the internal associations between loss of miR-101 expression and prognostic implications in patients with cancer.

MATERIALS AND METHODS

All relevant literature in electronic databases, including PubMed, ISI Web of Science, and Embase, up to March 1, 2017 were searched. Correlations between decreased miR-101 and clinicopathological parameters were defined by odds ratios (ORs). The degree of association between reduced miR-101 and survival outcome was evaluated by pooled hazard ratios (HRs) and relevant 95% CIs.

RESULTS

Twelve eligible studies with 2,088 patients were included in this meta-analysis. Decreased miR-101 expression was closely connected with poor overall survival, with a pooled HR of 2.15 (95% CI 1.71-2.7, P<0.001). This correlation was also revealed when stratified analysis was conducted with respect to ethnicity, cancer type, sample size, specimen source, and analysis model. However, decreased miR-101 was not associated with disease-free survival, recurrence-free survival, or progression-free survival, with a pooled HR of 1.59 (95% CI 0.83-3.03, P=0.128), despite a positive trend. In addition, reduced miR-101 was intimately related to poorer tumor differentiation (OR 2.17, 95% CI 1.14-4.13; P=0.019), advanced tumor classification (OR 5.25, 95% CI 3.39-8.12; P<0.001), and higher TNM stage (OR 6.18, 95% CI 3.79-10.09; P<0.001).

CONCLUSION

Our findings suggest that loss of miR-101 expression is correlated with worse overall survival in a variety of cancers, and could serve as a predictive indicator for clinicopathological features. Furthermore, miR-101 may become a feasible therapeutic target in most human cancers.

The Microtubule Network and Cell Death Are Regulated by an miR-34a/Stathmin 1/βIII-Tubulin Axis

MicroRNA-34a (miR-34a) is a master regulator of signaling networks that maintains normal physiology and disease and is currently in development as a miRNA-based therapy for cancer. Prior studies have reported low miR-34a expression in osteosarcoma; however, the molecular mechanisms underlying miR-34a activity in osteosarcoma are not well-defined. Therefore, this study evaluated the role of miR-34a in regulating signal transduction pathways that influence cell death in osteosarcoma. Levels of miR-34a were attenuated in human osteosarcoma cells and xenografts of the Pediatric Preclinical Testing Consortium (PPTC). Bioinformatics predictions identified stathmin 1 (STMN1) as a potential miR-34a target. Biotin pull-down assay and luciferase reporter analysis confirmed miR-34a target interactions within the STMN1 mRNA 3'-untranslated region. Overexpression of miR-34a in osteosarcoma cells suppressed STMN1 expression and reduced cell growth in vitro Restoration of miR-34a led to microtubule destabilization and increased βIII-tubulin expression, with corresponding G1-G2 phase cell-cycle arrest and apoptosis. Knockdown of the Sp1 transcription factor, by siRNA silencing, also upregulated βIII-tubulin expression in osteosarcoma cells, suggesting that miR-34a indirectly affects Sp1. Validating the coordinating role of miR-34a in microtubule destabilization, when miR-34a was combined with either microtubule inhibitors or chemotherapy, STMN1 phosphorylation was suppressed and there was greater cytotoxicity in osteosarcoma cells. These results demonstrate that miR-34a directly represses STMN1 gene and protein expression and upregulates βIII-tubulin, leading to disruption of the microtubule network and cell death.Implications: The miR-34a/STMN1/βIII-tubulin axis maintains the microtubule cytoskeleton in osteosarcoma, and combining miR-34a with microtubule inhibitors can be investigated as a novel therapeutic strategy. Mol Cancer Res; 15(7); 953-64. ©2017 AACR.

MicroRNA-19a promotes nasopharyngeal carcinoma by targeting transforming growth factor β receptor 2

MicroRNA (miR), a class of small non-coding RNA, function as key regulators in gene expression through directly binding to the 3' untranslated region of their target mRNA, which further leads to translational repression or mRNA degradation. miR-19a, a member of miR-17-92 cluster, has an oncogenic role in a variety of malignant tumors. However, the exact role of miR-19a in nasopharyngeal carcinoma (NPC) has not previously been studied. The present study aimed to investigate the function and mechanism of miR-19a in regulating the viability and invasion of NPC cells. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) data indicated that the expression levels of miR-17-92 cluster members (miR-17, miR-18a, miR-19a and miR-20a) were frequently increased in NPC tissues compared to the normal tissues. It was also demonstrated that miR-19a was significantly upregulated in NPC C666-1 cells compared to NP69 cells (P<0.01). Knockdown of miR-19a led to a significant decrease in the viability and invasion of NPC C666-1 cells (P<0.01), and induced increased protein expression levels of transforming growth factor β receptor 2 (TGFβR2), which was further identified as a direct target gene of miR-19a by using a luciferase reporter assay. Overexpression of TGFβR2 also suppressed the viability and invasion of C666-1 cells, similar to the effects of miR-19a inhibition. Furthermore, knockdown of TGFβR2 reversed the suppressive effects of miR-19a inhibition on C666-1 cell viability and invasion, suggesting that the role of miR-19a in mediating cell viability and invasion is through directly targeting TGFβR2 in NPC cells. In addition, RT-qPCR data demonstrated that the mRNA expression level of TGFβR2 was markedly reduced in NPC tissues and C666-1 cells. In summary, the present study demonstrated an oncogenic role of miR-19a in NPC via mediation of TGFβR2. Therefore, miR-19a may be a potential therapeutic target for NPC.

Knockdown of STMN1 enhances osteosarcoma cell chemosensitivity through inhibition of autophagy

Chemoresistance is a major cause for the poor prognosis of osteosarcoma (OS) patients. However, our understanding of mechanisms underlying chemoresistance in OS are limited. The present study aimed to investigate the effect of stathmin 1 (STMN1) on paclitaxel-induced chemoresistance, as well as the underlying mechanism. Western blot analysis data revealed that the expression level of STMN1 was dramatically increased in OS cell lines (HOS, Saos-2, U-2OS and MG-63), when compared to normal osteoblast hFOB1.19 cells. Furthermore, treatment with paclitaxel led to upregulation of STMN1 in U-2OS cells, accompanied by activation of autophagy, which may attenuate the cytotoxicity of paclitaxel in OS cells. Following knockdown of STMN1 expression, paclitaxel-induced autophagy was significantly reduced, accompanied by increased cytotoxicity of paclitaxel to U-2OS cells. In addition, blockade of mammalian target of rapamycin signaling attenuated the inhibitory effect of STMN1 knockdown on autophagy in OS cells. In conclusion, the present study demonstrated that knockdown of STMN1 enhances osteosarcoma cell chemosensitivity to paclitaxel through inhibition of autophagy. Therefore, STMN1 may be a potential target for the treatment of chemoresistant OS.

Autophagy-Regulating microRNAs and Cancer

Macroautophagy (autophagy herein) is a cellular stress response and a survival pathway that is responsible for the degradation of long-lived proteins, protein aggregates, as well as damaged organelles in order to maintain cellular homeostasis. Consequently, abnormalities of autophagy are associated with a number of diseases, including Alzheimers’s disease, Parkinson’s disease, and cancer. According to the current view, autophagy seems to serve as a tumor suppressor in the early phases of cancer formation, yet in later phases, autophagy may support and/or facilitate tumor growth, spread, and contribute to treatment resistance. Therefore, autophagy is considered as a stage-dependent dual player in cancer. microRNAs (miRNAs) are endogenous non-coding small RNAs that negatively regulate gene expression at a post-transcriptional level. miRNAs control several fundamental biological processes, and autophagy is no exception. Furthermore, accumulating data in the literature indicate that dysregulation of miRNA expression contribute to the mechanisms of cancer formation, invasion, metastasis, and affect responses to chemotherapy or radiotherapy. Therefore, considering the importance of autophagy for cancer biology, study of autophagy-regulating miRNA in cancer will allow a better understanding of malignancies and lead to the development of novel disease markers and therapeutic strategies. The potential to provide study of some of these cancer-related miRNAs were also implicated in autophagy regulation. In this review, we will focus on autophagy, miRNA, and cancer connection, and discuss its implications for cancer biology and cancer treatment.

MicroRNA-101 inhibits invasion and angiogenesis through targeting ITGA3 and its systemic delivery inhibits lung metastasis in nasopharyngeal carcinoma

Clinically, distant metastasis after primary treatment remains a key problem in nasopharyngeal carcinoma (NPC), and the treatment outcome of metastatic NPC remains disappointing, so there is a pressing need to identify novel therapeutic strategies. In accordance with our previous microarray data, we found that miR-101 was downregulated in NPC clinical specimens and cell lines. Ectopic expression of miR-101 significantly suppressed NPC cell migration, invasion and angiogenesis in vitro and inhibited angiogenesis and metastasis in vivo using the chicken chorioallantoic membrane model. Furthermore, ITGA3 was identified and validated as a novel target of miR-101, and the restoration of ITGA3 expression potently rescued the suppressive effects of miR-101. In addition, NPC patients with high ITGA3 expression had poorer overall survival and distant metastasis-free survival than patients with low ITGA3 expression, and ITGA3 overexpression was an independent poor prognostic factor in NPC. More importantly, we demonstrated that the systemic delivery of lentivirus-mediated miR-101 abrogated the lung metastatic colonization formation of NPC cells without obvious toxicity. Our study elucidates the molecular mechanisms of miR-101/ITGA3 pathway in regulating NPC metastasis and angiogenesis, and the systemic delivery of miR-101 provides a potent evidence for the development of a novel microRNA-targeting anticancer strategy for NPC patients.

ERK2-ZEB1-miR-101-1 axis contributes to epithelial-mesenchymal transition and cell migration in cancer

Regulation of metastasis continues to remain enigmatic despite our improved understanding of cancer. Identification of microRNAs associated with metastasis in the recent past has provided a new hope. Here, we show how microRNA-101 (miR-101) regulates two independent processes of cellular metastasis by targeting pro-metastatic upstream regulatory transcription factors, ZEB1 and ZEB2, and downstream effector-actin modulators, RHOA and RAC1, providing a single target for therapeutic intervention. Further, we depict how down-regulation of miR-101 by extracellular signal-regulated kinase-2 (ERK2) is vital for MAP kinase pathway induced cellular migration and mesenchymal transition. Importantly, EKR2 induced expression of ZEB1 seems essential for down-regulation of miR-101-1 and induction of EMT. Given the role of EMT in metastasis, we also observe a significant correlation between miR-101 expression and lymph node metastasis; and identify the ERK2-ZEB1-miR-101-1 pathway active in breast cancer tissues, with an apparent clinicopathological implication.

Stathmin-dependent molecular targeting therapy for malignant tumor: the latest 5 years' discoveries and developments

Knowledge of the molecular mechanisms on malignant tumors is very critical for the development of new treatment strategies like molecularly targeted therapies. In last 5 years, many investigations suggest that stathmin is over-expressed in a variety of human malignant tumors, and potentially promotes the occurrence and development of tumors. Rather, down-regulation of stathmin can reduce cell proliferation, motility and metastasis and induce apoptosis of malignant tumors. Thus, a stathmin antagonist, such as a specific inhibitor (antibody, small molecule compound, peptide, or siRNA), may be a novel strategy of molecular targeted therapy. This review summarizes the research progress of recent 5 years on the role of stathmin in tumorigenesis, the molecular mechanisms and development of anti-stathmin treatment, which suggest that continued investigations into the function of stathmin in the tumorigenesis could lead to more rationally designed therapeutics targeting stathmin for treating human malignant tumors.

MicroRNA-33b Inhibits the Proliferation and Migration of Osteosarcoma Cells via Targeting Hypoxia-Inducible Factor-1α

Recently, microRNA (miR)-33b has been demonstrated to act as a tumor suppressor in osteosarcoma. However, the regulatory mechanism of miR-33b in osteosarcoma cell proliferation and migration remains largely unknown. In this study, real-time PCR showed that miR-33b was significantly downregulated in osteosarcoma tissues compared to their matched adjacent nontumor tissues. Its expression was also decreased in several common osteosarcoma cell lines, including Saos-2, MG63, U2OS, and SW1353, when compared to normal osteoblast cell line hFOB. Overexpression of miR-33b suppressed U2OS cell proliferation and migration. HIF-1α was further identified as a target of miR-33b, and its protein levels were reduced after overexpression of miR-33b in U2OS cells. Moreover, overexpression of HIF-1α significantly reversed the suppressive effect of miR-33b on U2OS cell proliferation and migration. In addition, HIF-1α was found to be significantly upregulated in osteosarcoma tissues compared to adjacent nontumor tissues, and their expression levels were inversely correlated to the miR-33b levels in osteosarcoma tissues. According to these findings, miR-33b plays a suppressive role in the regulation of osteosarcoma cell proliferation and migration via directly targeting HIF-1α. Therefore, we suggest that the miR-33b/HIF-1α axis may become a promising therapeutic target for osteosarcoma.

Stathmin1 increases radioresistance by enhancing autophagy in non-small-cell lung cancer cells

Radioresistance has been demonstrated to be involved in the poor prognosis of patients with non-small-cell lung cancer (NSCLC). However, the underlying mechanism remains largely unclear. Investigation on special therapeutic targets associated with radioresistance shows promises for the enhancement of clinical radiotherapy effect toward NSCLC. This study aimed to reveal the role of Stathmin1 (STMN1) in radioresistance in NSCLC as well as the underlying mechanism. Our data showed that the protein levels of STMN1 were significantly upregulated in NSCLC cells subjected to radiation, accompanied with the activation of autophagy. Knockdown of STMN1 expression enhanced the sensitivity of NSCLC cells to X-ray, and the radiation-induced autophagy was also inhibited. Molecular mechanism investigation showed that knockdown of STMN1 expression upregulated the activity of phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) signaling pathway in NSCLC cells. Moreover, the activation of PI3K/mTOR signaling showed an inhibitory effect on the autophagy and radioresistance induced by STMN1 in NSCLC cells. In addition, luciferase reporter assay data indicated that STMN1 was a direct target gene of miR-101, which had been reported to be an inhibitor of autophagy. Based on these data, we suggest that as a target gene of miR-101, STMN1 promotes the radioresistance by induction of autophagy through PI3K/mTOR signaling pathway in NSCLC. Therefore, STMN1 may become a potential therapeutic target for NSCLC radiotherapy.

MiR-593 mediates curcumin-induced radiosensitization of nasopharyngeal carcinoma cells via MDR1

Curcumin (Cur) exhibits radiosensitization effects to a variety of malignant tumors. The present study investigates the radiosensitizing effect of Cur on nasopharyngeal carcinoma (NPC) cells and whether its mechanism is associated with microRNA-593 (miR-593) and multidrug resistance gene 1 (MDR1). A clonogenic assay was performed to measure the radiosensitizing effect. The expression of miR-593 and MDR1 was analyzed by quantitative polymerase chain reaction (qPCR) or western blot assay. A transplanted tumor model was established to identify the radiosensitizing effect in vivo. A luciferase-based reporter was constructed to evaluate the effect of direct binding of miR-593 to the putative target site on the 3' UTR of MDR1. The clonogenic assay showed that Cur enhanced the radiosensitivity of cells. Cur (100 mg/kg) combined with 4 Gy irradiation inhibited the growth of a transplanted tumor model in vivo, resulting in the higher inhibition ratio compared with the radiotherapy-alone group. These results demonstrated that Cur had a radiosensitizing effect on NPC cells in vivo and in vitro; Cur-mediated upregulation of miR-593 resulted in reduced MDR1 expression, which may promote radiosensitivity of NPC cells.

mir-129-5p Attenuates Irradiation-Induced Autophagy and Decreases Radioresistance of Breast Cancer Cells by Targeting HMGB1

BACKGROUND This study aimed to determine the role of miR-129-5p in irradiation-induced autophagy in breast cancer cells and to investigate its downstream regulation in autophagy-related radiosensitivity. MATERIAL AND METHODS Relative miR-129-5p expression in breast cancer cell lines MCF-7, MDA-MB-231, BT474, and BT549, and in 1 non-tumorigenic breast epithelial cell line, MCF-10A, was compared. The effect of miR-129-5p on irradiation-induced autophagy and radiosensitivity of the cancer cells was explored. The regulative effect of miR-129-5p on HMGB1 and the functional role of this axis in autophagy and radiosensitivity were also studied. RESULTS Ectopic expression of miR-129-5p sensitized MDA-MD-231 cells to irradiation, while knockdown of miR-129-5p reduced radiosensitivity of MCF-7 cells. MiR-129-5p overexpression inhibited irradiation-induced autophagy. HMGB1 is a direct functional target of miR-129-5p in breast cancer cells. MiR-129-5p may suppress autophagy and decrease radioresistance of breast cancer cells by targeting HMGB1. CONCLUSIONS The miR-129-5p/HMGB1 axis can regulate irradiation-induced autophagy in breast cancer and might be an important pathway in regulating radiosensitivity of breast cancer cells.

MiR-185-3p and miR-324-3p Predict Radiosensitivity of Nasopharyngeal Carcinoma and Modulate Cancer Cell Growth and Apoptosis by Targeting SMAD7

Background

MiR-185-3p and miR-324-3p are 2 miRNAs that regulate nasopharyngeal carcinoma (NPC) radioresistance. This study tried to assess the clinical values of low miR-185-3p and low miR-324-3p expression in predicting response to radiotherapy (RT) and prognosis of NPC and to explore their new downstream targets.

Material/Methods

We recruited 80 patients with primary NPC. MiR-185-3p and miR-324-3p expression in the tumor tissues before and after RT or chemoradiotherapy (CRT) were determined. Overall survival and recurrence-free survival curves were estimated to assess the prognostic values of these 2 miRNAs. Their target was predicted using an online database and verified using dual luciferase assay, qRT-PCR, and Western blot analysis. In addition, the function of miR-185-3p/miR-324-3p-SMAD7 axis in NPC cells was investigated.

Results

The expression of miR-185-3p and miR-324-3p was significantly reduced after RT in radioresistant but not in radiosensitive cases. Although miR-185-3p and miR-324-3p are not independent prognostic indicators of overall survival of NPC, their low expression is still associated with poor overall survival and recurrence-free survival. In addition, miR-185-3p and miR-324-3p can modulate growth and apoptosis of NPC cells, partly via SMAD7.

Conclusions

Combined low miR-185-3p and miR-324-3p might be important markers for prediction of low response to RT/CRT and poor overall survival and recurrence-free survival. MiR-185-3p and miR-324-3p can modulate NPC cell growth and apoptosis, at least partly through targeting SMAD7.