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

Transcriptional signature of early cisplatin drug-tolerant persister cells in lung adenocarcinoma

Resistance to cisplatin is the main cause of treatment failure in lung adenocarcinoma. Drug-tolerant-persister (DTP) cells are responsible for intrinsic resistance, since they survive the initial cycles of treatment, representing a reservoir for the emergence of clones that display acquired resistance. Although the molecular mechanisms of DTP cells have been described, few studies have investigated the earliest molecular alterations of DTP cells in intrinsic resistance to cisplatin. In this work, we report a gene expression signature associated with the emergence of cisplatin-DTP cells in lung adenocarcinoma cell lines. After a single exposure to cisplatin, we sequenced the transcriptome of cisplatin-DTPs to identify differentially expressed genes. Bioinformatic analysis revealed that early cisplatin-DTP cells deregulate metabolic and proliferative pathways to survive the drug insult. Interaction network analysis identified three highly connected submodules in which SOCS1 had a significant participation in controlling the proliferation of cisplatin-DTP cells. Expression of the candidate genes and their corresponding protein was validated in lung adenocarcinoma cell lines. Importantly, the expression level of SOCS1 was different between CDDP-susceptible and CDDP-resistant lung adenocarcinoma cell lines. Moreover, knockdown of SOCS1 in the CDDP-resistant cell line partially promoted its susceptibility to CDDP. Finally, the clinical relevance of the candidate genes was analyzed in silico, according to the overall survival of cisplatin-treated patients from The Cancer Genome Atlas. Survival analysis showed that downregulation or upregulation of the selected genes was associated with overall survival. The results obtained indicate that these genes could be employed as predictive biomarkers or potential targets to improve the effectiveness of CDDP treatment in lung cancer patients.

Systematic review of comparative transcriptomic studies of cellular resistance to genotoxic stress

The development of resistance by tumor cells to various types of therapy is a significant problem that decreases the effectiveness of oncology treatments. For more than two decades, comparative transcriptomic studies of tumor cells with different sensitivities to ionizing radiation and chemotherapeutic agents have been conducted in order to identify the causes and mechanisms underlying this phenomenon. However, the results of such studies have little in common and often contradict each other. We have assumed that a systematic analysis of a large number of such studies will provide new knowledge about the mechanisms of development of therapeutic resistance in tumor cells. Our comparison of 123 differentially expressed gene (DEG) lists published in 98 papers suggests a very low degree of consistency between the study results. Grouping the data by type of genotoxic agent and tumor type did not increase the similarity. The most frequently overexpressed genes were found to be those encoding the transport protein ABCB1 and the antiviral defense protein IFITM1. We put forward a hypothesis that the role played by the overexpression of the latter in the development of resistance may be associated not only with the stimulation of proliferation, but also with the limitation of exosomal communication and, as a result, with a decrease in the bystander effect. Among down regulated DEGs, BNIP3 was observed most frequently. The expression of BNIP3, together with BNIP3L, is often suppressed in cells resistant to non-platinum genotoxic chemotherapeutic agents, whereas it is increased in cells resistant to ionizing radiation. These observations are likely to be mediated by the binary effects of these gene products on survival, and regulation of apoptosis and autophagy. The combined data also show that even such obvious mechanisms as inhibition of apoptosis and increase of proliferation are not universal but show multidirectional changes.

Association of long noncoding RNA MALAT1 with the radiosensitivity of lung adenocarcinoma cells via the miR-140/PD-L1 axis

Objective

To investigate the effect of MALAT1 on the modulating the radiosensitivity of lung adenocarcinoma, through regulation of the expression of the miR-140/PD-L1 axis.

Methods

The online databases UALCAN and dbDEMC were searched for the MALAT1 and miR-140 expressions in patients with lung adenocarcinoma (LUAD), respectively. Then analyze their relationship with overall survival rates separately in the UALCAN and ONCOMIR databases. A functional analysis was performed for A549 cells by transfecting small-interfering RNAs or corresponding plasmids after radiotherapy. Xenograft models of LUAD exposed to radiation were established to further observe the effects of MALAT1 on the radiosensitivity of LUAD. The luciferase assay and reverse transcription-polymerase chain reaction were performed to assess the interaction between miR-140 and MALAT1 or PD-L1.

Results

MALAT1 were overexpressed in human LUAD tumor tissues and cell lines, while miR-140 were inhibited. MALAT1 knockdown or miR-140 increase suppressed cell proliferation and promoted cell apoptosis in LUAD after irradiation. LUAD xenograft tumor growth was also inhibited by MALAT1 knockdown combined with irradiation. miR-140 could directly bind with MALAT1 or PD-L1. Furthermore, MALAT1 knockdown inhibited PD-L1 mRNA and protein expressions by upregulating miR-140 in LUAD cells.

Conclusion

MALAT1 may function as a sponge for miR-140a-3p to enhance the PD-L1 expression and decrease the radiosensitivity of LUAD. Our results suggest that MALAT1 might be a promising therapeutic target for the radiotherapy sensitization of LUAD.

LncRNAs as Theragnostic Biomarkers for Predicting Radioresistance in Cancer: A Systematic Review and Meta-Analysis

Background

Radioresistance is the major obstacle after cancer radiotherapy. The dysregulation of long non-coding RNAs (lncRNAs) was closely related the radioresistance response. This meta-analysis was aimed to interpret the relationship between lncRNAs and radiotherapy responses in different cancers.

Method

The studies were selected from databases including PubMed, ISI Web of Science, Embase, Google Scholar, PMC, and CNKI (China National Knowledge Infrastructure). The publication time was limited to before March 20, 2021. The hazard ratios (HRs) and 95% confidence interval were calculated with random-effects models. Subgroup analyses, sensitivity analyses, and publication bias were also conducted.

Result

Twenty-seven lncRNAs in 14 cancer types were investigated, in which 23 lncRNAs were upregulated and four lncRNAs were downregulated. Dysregulation of these lncRNAs were found to be related to radioresistance response. The pooled HR and 95% confidence interval for the combined up-regulated lncRNAs was 1.73 (95% CI=1.50-2.00; P< 0.01) and down-regulated lncRNAs was 2.09 (95% CI= 1.60-2.72; P< 0.01). The HR values of the subgroup analysis for glioma (HR= 2.22, 95% CI= 1.79-2.74; p< 0.01), non-small cell lung cancer (HR=1.48, 95% CI=1.18-1.85; P<0.01), nasopharyngeal carcinoma (HR=4.26; 95% CI= 1.58-11.46; P< 0.01), and breast cancer (HR=1.29; 95% CI= 1.08-1.54; P< 0.01) were obtained. Moreover, the expression of lncRNAs was significantly related to overall survival of patients no matter if the sample size was >50 or not. In addition, the HR values of the subgroup analysis for lncRNA H19 (HR=2.68; 95% CI= 1.92-3.74; P <0.01), lncRNA FAM201A (HR=2.15; 95% CI= 1.15-3.99; P <0.01), and lncRNA HOTAIR (HR=1.22; 95% CI= 0.98-1.54; P =0.08) were also obtained.

Conclusion

LncRNAs can induce cancer radioresistance by regulating cell death-related signaling pathways. Results indicated that lncRNAs, especially lncRNA H19, FAM201A, and HOTAIR, could be considered as a predictive theragnostic biomarker to evaluate radiotherapy response.

The DNA Damage Response Is Differentially Involved in HPV-Positive and HPV-Negative Radioresistant Head and Neck Squamous Cell Carcinoma

Simple Summary

Head and neck cancers can be divided in two major groups according to their risk factors, being high-risk human papillomavirus related (HPV-positive) and alcohol and tobacco related (HPV-negative) head and neck cancers. The majority of the locally advanced patients are treated with radiotherapy. However, up to 50% of these patients show local recurrences. The majority of these recurrences are linked to resistance to radiotherapy treatment. It is known that the response to DNA damage, also a process called the DNA damage response, is an important factor that determines the effectivity of radiotherapy. Here, we assessed the role of the DNA damage response in the resistance process to radiotherapy of head and neck cancers, by generating head and neck cancer cells resistant to radiotherapy. We show that the DNA damage response is differentially involved in the resistance process of HPV-positive and HPV-negative head and neck cancer cells. More specifically, HPV-positive radiotherapy-resistant cells showed increased ability to repair the DNA damage induced by radiotherapy. HPV-negative radiotherapy-resistant cells showed increased capacity to replicate after radiotherapy treatment. Despite this difference, inhibition of the DNA damage response enhanced the effect of radiotherapy in both groups.

Abstract

Radioresistance is a major cause of recurrences and radiotherapy (RT) failure in head and neck squamous cell carcinoma (HNSCC). DNA damage response (DDR) is known to be important for RT response, but its role in radioresistance is not fully understood. Here, we assessed the role of DDR in the radioresistance process of HNSCC by generating radioresistant clones from both HPV-positive SCC154 and HPV-negative SCC61 cells. We show that fractionated RT decreased RT response of HPV-positive and HPV-negative radioresistant clones in vitro and in vivo. Moreover, HPV-positive and HPV-negative radioresistant clones were characterized by differential DDR response. HPV-positive radioresistant clones showed less residual double-strand break damage and increased G2/M arrest recovery after RT, indicating an acquisition of increased DDR kinetics. In contrast, HPV-negative radioresistant clones showed less micronucleated cells after RT and increased survival upon checkpoint inhibition, indicating an increased replicative capacity. Inhibiting key factors of DDR in combination with RT rescued the radioresistant phenotype of both HPV-positive and HPV-negative radioresistant clones. Altogether, our results not only highlight the importance of DDR response in the radioresistance process of HPV-positive and HPV-negative HNSCC, but also provide possibilities for new therapies for HNSCC patients in recurrent settings.

Nursing Observation on the Clinical Efficacy and Toxicity of Lobaplatin Compared with Cisplatin in the Treatment of Locally Advanced Hypopharyngeal Carcinoma Based on Intelligent CT Imaging

With the acceleration of people's life rhythm, the incidence of hypopharyngeal cancer has generally increased. This study mainly explores the clinical efficacy and toxicity of lobaplatin compared with cisplatin in the treatment of locally advanced hypopharyngeal carcinoma based on intelligent CT imaging. Group A received lobaplatin combined with docetaxel induction chemotherapy for 2 cycles after cisplatin combined with intensity-modulated radiotherapy. Lobaplatin was added to the patient, then, 200 ml of 5% glucose was added, and the patient was injected intravenously for 1.8 hours. After 2 cycles of induction chemotherapy, simultaneous lobaplatin chemotherapy was performed every week for 5 weeks (10 mg/week), and the efficacy was evaluated after 4 consecutive courses of treatment. Group B received cisplatin combined with docetaxel induction chemotherapy after 2 cycles of cisplatin combined with intensity-modulated radiotherapy. Group C was the control group and was not treated with cisplatin or docetaxel. Stomach protection treatment was given in time throughout the treatment process. All patients underwent normal CT (NCCT) and enhanced CT (CECT) examinations before treatment. We extracted 5 mm plain scan CTQNCCT and enhanced CT (CECT) digital DICOM images from the PACS system for omics feature selection. Toxic and side effects are rated in different degrees according to the evaluation criteria of the National Cancer Institute (NCD) common adverse events. Blood routine and liver and kidney function tests were checked every week, and the medication was stopped immediately if there is a serious reaction. In addition, in vitro cell culture was set up to test the inhibitory effect of cisplatin and lobaplatin on the proliferation of cancer cells. The incidence of digestive tract reaction was 13.0% in the A plan group and 58.3% in the B plan group. The A group was lower than the B group, and the difference was statistically significant (P=0.001 < 0.05). Compared with cisplatin, lobaplatin has a milder gastrointestinal reaction, and there is no common hepatic and renal toxicity of cisplatin. This study is helpful to provide guidance for the clinical efficacy of locally advanced hypopharyngeal cancer treatment.

RP11‑156L14.1 regulates SSR1 expression by competitively binding to miR‑548ao‑3p in hypopharyngeal squamous cell carcinoma

Emerging studies have demonstrated that long non-coding RNAs (lncRNAs) play essential roles in tumorigenesis. However, the role and function of lncRNAs in hypopharyngeal squamous cell carcinoma (HSCC) have not been completely elucidated. The present study explored the function of a novel lncRNA, RP11-156L14.1, in HSCC. RP11-156L14.1 was revealed to be highly expressed in HSCC tissues and cell lines. Knockdown of RP11-156L14.1 inhibited proliferation, migration, and invasion in HSCC cells. Furthermore, RP11-156L14.1 regulated epithelial-mesenchymal transition (EMT) by controlling EMT-related protein expression. Mechanistically, RP11-156L14.1 exerted its function as a competing endogenous RNA (ceRNA) and directly interacted with miR-548ao-3p. The present study also demonstrated that miR-548ao-3p regulated signal sequence receptor subunit 1 (SSR1) expression by targeting SSR1 3′-UTR. Moreover, the xenograft HSCC tumor model revealed that knockdown of RP11-156L14.1 markedly suppressed HSCC tumor growth in vivo. In summary, these findings indicated that the lncRNA RP11-156L14.1 functions as an oncogene in HSCC by competing with miR-548ao-3p in regulating SSR1 expression. The RP11-156L14.1/miR-548ao-3p/SSR1 axis could be utilized as a potential novel biomarker and therapeutic target for HSCC.

Radioresistance, DNA Damage and DNA Repair in Cells With Moderate Overexpression of RPA1

Molecular responses to genotoxic stress, such as ionizing radiation, are intricately complex and involve hundreds of genes. Whether targeted overexpression of an endogenous gene can enhance resistance to ionizing radiation remains to be explored. In the present study we take an advantage of the CRISPR/dCas9 technology to moderately overexpress the RPA1 gene that encodes a key functional subunit of the replication protein A (RPA). RPA is a highly conserved heterotrimeric single-stranded DNA-binding protein complex involved in DNA replication, recombination, and repair. Dysfunction of RPA1 is detrimental for cells and organisms and can lead to diminished resistance to many stress factors. We demonstrate that HEK293T cells overexpressing RPA1 exhibit enhanced resistance to cell killing by gamma-radiation. Using the alkali comet assay, we show a remarkable acceleration of DNA breaks rejoining after gamma-irradiation in RPA1 overexpressing cells. However, the spontaneous rate of DNA damage was also higher in the presence of RPA1 overexpression, suggesting alterations in the processing of replication errors due to elevated activity of the RPA protein. Additionally, the analysis of the distributions of cells with different levels of DNA damage showed a link between the RPA1 overexpression and the kinetics of DNA repair within differentially damaged cell subpopulations. Our results provide knew knowledge on DNA damage stress responses and indicate that the concept of enhancing radioresistance by targeted alteration of the expression of a single gene is feasible, however undesired consequences should be considered and evaluated.

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.

Knockdown of lncRNA BLACAT1 enhances radiosensitivity of head and neck squamous cell carcinoma cells by regulating PSEN1

OBJECTIVE

This work focused on the function role and underlying mechanism of BLACAT1 in regulating the radiosensitivity of head and neck squamous cell carcinoma (HNSCC) cells via PSEN1.

METHODS

BLACAT1 and PSEN1 expression in HNSCC tissues and cells were measured by qRT-PCR. Kaplan-Meier method and Spearman's correlation analysis determined the prognostic roles and association of BLCAT1 and PSEN1 in HNSCC. The impacts of BLACAT1 and PSEN1, alone and in combination, on radiosensitivity of HNSCC cells were separately assessed through CCK-8, colony formation, flow cytometry, western blot and γH2AX foci staining assays.

RESULTS

Our study disclosed that BLACAT1 and PSEN1 were both in association with poor prognosis and radioresistance of HNSCC cells. BLACAT1 knockdown improved the radiosensitivity of HNSCC cells by changing cellular activities containing repressed cell viability, accelerated cell apoptosis, induced cell cycle arrest, and stimulated DNA damage response. Further, we found that PSEN1 was positively correlated with BLACAT1. Rescue assays confirmed that BLACAT1 regulated the radiosensitivity of HNSCC cells by modulating PSEN1.

CONCLUSION

We revealed that BLACAT1 knockdown enhanced radioresistance of HNSCC cells via regulating PSEN1, exposing the probable target role of BLACAT1 in HNSCC.

ADVANCES IN KNOWLEDGE

This was the first time that the pivotal role of BLACAT1 was investigated in HNSCC, which provided a novel therapeutic direction for HNSCC patients.

Silencing Snail Reverses Epithelial-Mesenchymal Transition and Increases Radiosensitivity in Hypopharyngeal Carcinoma

Purpose

Radioresistance in response to radiotherapy leads to cancer recurrence and poor survival in hypopharyngeal carcinoma patients. Previous studies indicate that ionizing radiation (IR) can induce epithelial–mesenchymal transition (EMT) that promotes the radioresistance, migration and invasiveness of tumors. The aim of this study was to explore the role of Snail in EMT and acquired radioresistance in hypopharyngeal carcinoma.

Methods

Radioresistance human hypopharyngeal carcinoma cells (FaduRR) were previously established from the Fadu cell line. Radiosensitivity was measured by colony forming assay. Western blot and Quantitative real-time PCR were used to detect the expression of EMT phenotypes and AKT/GSK-3β/Snail signaling pathway related proteins in Fadu+4Gy and FaduRR cells. Transwell and wound-healing assays were used to measure cell migration and invasiveness. EMT-related proteins and Snail expression were assessed in 80 hypopharyngeal carcinoma patient samples from radiosensitive and radioresistance groups using immunohistochemistry. Snail was silenced to evaluate its effects on EMT, radioresistance, migration, and invasiveness of FaduRR cells.

Results

The molecular characteristics of EMT were observed following radiation treatment, with migration, invasiveness and radioresistance enhanced in Fadu+4Gy and FaduRR cells. Moreover, we demonstrated that IR-induced EMT by activating the AKT/GSK-3β/Snail signaling pathway and that Snail silencing reversed EMT and attenuated radioresistance in FaduRR cells. Significant differences in EMT-related proteins and Snail expression were observed between radiosensitive and resistant group.

Conclusion

We demonstrate that IR can trigger EMT and enhance the migration, invasiveness, and radioresistance of FaduRR cells through the AKT/GSK-3β/Snail axis. Snail silencing could attenuate these effects and represents a novel therapeutic target for EMT-induced radioresistance in hypopharyngeal carcinoma.

Knockdown of LINC00511 promotes radiosensitivity of thyroid carcinoma cells via suppressing JAK2/STAT3 signaling pathway

Thyroid carcinoma is the most widespread malignancy in endocrine system with the increasing incidence. Despite of the advanced approaches to the management of thyroid carcinoma, the therapeutic effects remain unpleasant largely due to the radiosensitivity of thyroid carcinoma cells. LncRNAs play important part in the tumorigenesis and development, especially in the radiosensitivity of tumor cells. However, their roles in thyroid carcinoma still needed to be explored deeply. The purpose of our research is to inspect the possible biological role and regulation mechanism of LINC00511 desirable for therapies of thyroid carcinoma patients. In the present study, LINC00511 was significantly overexpressed in thyroid carcinoma and its silencing boosted radiosensitivity of thyroid carcinoma cells. Then we unveiled that LINC00511 regulated JAK2/STAT3 signaling pathway which was resistant to radiation treatment. Besides, TAF1 modulated JAK2 at transcriptional level. Moreover, LINC00511 bound to TAF1 and further promoted JAK2 expression. In conclusion, rescue experiments verified that the radiosensitivity of thyroid carcinoma cells was attributed to LINC00511/TAF1/JAK2/STAT3 axis. The current paper investigated the underlying mechanism of LINC00511 and set a new therapeutic direction for the therapy of thyroid carcinoma.

Metformin Suppresses Hypopharyngeal Cancer Growth by Epigenetically Silencing Long Non-coding RNA SNHG7 in FaDu Cells

Local recurrence after therapy remains a challenging problem for hypopharyngeal cancer (HPC) due to the chemotherapy resistance. Metformin is associated with reduced cancer risk through promoting global DNA methylation in cancer cells by controlling S-adenosylhomocysteine (SAHH) activity. However, the mechanisms by which metformin inhibits HPC remain elusive. In this study, we aim to investigate the role of metformin in HPC and illustrate the mechanism by which metformin regulates long non-coding RNAs (lncRNAs) expression. CCK-8 and annexin-V/PI double staining were performed to analyze the cell viability and apoptosis. LncRNA microarray analysis, QPCR, methylation specific PCR, Western blot and RNA Immunoprecipitation were performed to analyze the molecular mechanism, Here, we report that metformin inhibits FaDu cell proliferation in time- and dose-dependent manner by suppressing lncRNA SNHG7. Further investigations revealed that SNHG7 interacted with SAHH and metformin decreased SNHG7 expression by activating SAHH activity. Increased SAHH activity resulted in upregulating DNMT1 expression, leading to hypermethylation of SNHG7 promotor. In addition, upregulation of SNHG7 was associated with advanced stage. The patients with high SNHG7 have lower overall survival than that of with low SNHG7. Interestingly, SNHG7 levels were higher in taxol resistant patients than in taxol sensitive patients. Metformin sensitizes FaDu cells to taxol and irradiation through decreasing SNHG7. In conclusion, our recent study demonstrates that metformin inhibits FaDu cell proliferation by decreasing SNHG7 expression via SAHH-mediated DNA methylation. These findings indicate that combined metformin with paclitaxel or irradiation would be a novel therapeutic strategy to overcome resistance and prevent recurrence in HPC.

lncRNA Expression after Irradiation and Chemoexposure of HNSCC Cell Lines

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cause of cancer mortality in the world. To improve the quality of diagnostics and patients' treatment, new and effective biomarkers are needed. Recent studies have shown that the expression level of different types of long non-coding RNAs (lncRNAs) is dysregulated in HNSCC and correlates with many biological processes. In this study, the response of lncRNAs in HNSCC cell lines after exposure to irradiation and cytotoxic drugs was examined. The SCC-040, SCC-25, FaDu, and Cal27 cell lines were treated with different radiation doses as well as exposed to cisplatin and doxorubicin. The expression changes of lncRNAs after exposure to these agents were checked by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Target prediction was performed using available online tools and classified into specific biological processes and cellular pathways. The results indicated that the irradiation, as well as chemoexposure, causes changes in lncRNA expression and the effect depends on the cell line, type of agents as well as their dose. After irradiation using the dose of 5 Gy significant dysregulation of 4 lncRNAs, 10 Gy-5 lncRNAs, and 20 Gy-3 lncRNAs, respectively, were observed in all cell lines. Only lncRNAs Zfhx2as was down-regulated in all cell lines independently of the dose used. After cisplatin exposure, 14 lncRNAs showed lower and only two higher expressions. Doxorubicin resulted in lower expressions of eight and increased four of lncRNAs. Common effects of cytotoxic drugs were observed in the case of antiPEG11, BACE1AS, PCGEM1, and ST7OT. Analysis of the predicted targets for dysregulated lncRNAs indicated that they are involved in important biological processes, regulating cellular pathways connected with direct response to irradiation or chemoexposure, cellular phenotype, cancer initiating cells, and angiogenesis. Both irradiation and chemoexposure caused specific changes in lncRNAs expression. However, the common effect is potentially important for cellular response to the stress and survival. Further study will show if lncRNAs are useful tools in patients' treatment monitoring.

Differently expressed long noncoding RNAs and mRNAs in TK6 cells exposed to low dose hydroquinone

Previous studies have shown that long noncoding RNAs (lncRNAs) were related to human carcinogenesis and might be designated as diagnosis and prognosis biomarkers. Hydroquinone (HQ), as one of the metabolites of benzene, was closely relevant to occupational benzene poisoning and occupational leukemia. Using high-throughput sequencing technology, we investigated differences in lncRNA and mRNA expression profiles between experimental group (HQ 20 μmol/L) and control group (PBS). Compared to control group, a total of 65 lncRNAs and 186 mRNAs were previously identified to be aberrantly expressed more than two fold change in experimental group. To validate the sequencing results, we selected 10 lncRNAs and 10 mRNAs for quantitative real-time PCR (qRT-PCR). Through GO annotation and KEGG pathway analysis, we obtained 3 mainly signaling pathways, including P53 signaling pathway, which plays an important role in tumorigenesis and progression. After that, 25 lncRNAs and 32 mRNAs formed the lncRNA-mRNA co-expression network were implemented to play biological functions of the dysregulated lncRNAs transcripts by regulating gene expression. The lncRNAs target genes prediction provided a new idea for the study of lncRNAs. Finally, we have another important discovery, which is screened out 11 new lncRNAs without annotated. All these results uncovered that lncRNA and mRNA expression profiles in TK6 cells exposed to low dose HQ were different from control group, helping to further study the toxicity mechanisms of HQ and providing a new direction for the therapy of leukemia.

Roles of Long Noncoding RNAs in Recurrence and Metastasis of Radiotherapy-Resistant Cancer Stem Cells

Radiotherapy is a well-established therapeutic regimen applied to treat at least half of all cancer patients worldwide. Radioresistance of cancers or failure to treat certain tumor types with radiation is associated with enhanced local invasion, metastasis and poor prognosis. Elucidation of the biological characteristics underlying radioresistance is therefore critical to ensure the development of effective strategies to resolve this issue, which remains an urgent medical problem. Cancer stem cells (CSCs) comprise a small population of tumor cells that constitute the origin of most cancer cell types. CSCs are virtually resistant to radiotherapy, and consequently contribute to recurrence and disease progression. Metastasis is an increasing problem in resistance to cancer radiotherapy and closely associated with the morbidity and mortality rates of several cancer types. Accumulating evidence has demonstrated that radiation induces epithelial-mesenchymal transition (EMT) accompanied by increased cancer recurrence, metastasis and CSC generation. CSCs are believed to serve as the basis of metastasis. Previous studies indicate that CSCs contribute to the generation of metastasis, either in a direct or indirect manner. Moreover, the heterogeneity of CSCs may be responsible for organ specificity and considerable complexity of metastases. Long noncoding RNAs (lncRNAs) are a class of noncoding molecules over 200 nucleotides in length involved in the initiation and progression of several cancer types. Recently, lncRNAs have attracted considerable attention as novel critical regulators of cancer progression and metastasis. In the current review, we have discussed lncRNA-mediated regulation of CSCs following radiotherapy, their association with tumor metastasis and significance in radioresistance of cancer.