MicroRNAs and Their Impact on Radiotherapy for Cancer

miRNAs in radiotherapy resistance of cancer; a comprehensive review

While intensity-modulated radiation therapy-based comprehensive therapy increases outcomes, cancer patients still have a low five-year survival rate and a high recurrence rate. The primary factor contributing to cancer patients' poor prognoses is radiation resistance. A class of endogenous non-coding RNAs, known as microRNAs (miRNAs), controls various biological processes in eukaryotes. These miRNAs influence tumor cell growth, death, migration, invasion, and metastasis, which controls how human carcinoma develops and spreads. The correlation between the unbalanced expression of miRNAs and the prognosis and sensitivity to radiation therapy is well-established. MiRNAs have a significant impact on the regulation of DNA repair, the epithelial-to-mesenchymal transition (EMT), and stemness in the tumor radiation response. But because radio resistance is a complicated phenomena, further research is required to fully comprehend these mechanisms. Radiation response rates vary depending on the modality used, which includes the method of delivery, radiation dosage, tumor stage and grade, confounding medical co-morbidities, and intrinsic tumor microenvironment. Here, we summarize the possible mechanisms through which miRNAs contribute to human tumors' resistance to radiation.

microRNA blood signature for localized radiation injury

A radiological accident, whether from industrial, medical, or malicious origin, may result in localized exposure to high doses of ionizing radiations, leading to the development of local radiation injury (LRI), that may evolve toward deep ulceration and necrosis of the skin and underlying tissues. Early diagnosis is therefore crucial to facilitate identification and management of LRI victims. Circulating microRNAs (miRNA) have been studied as potential diagnostic biomarkers of several diseases including hematological defects following whole-body irradiation (WBI). This study aims to identify a blood miRNA signature associated with LRI in a preclinical C57BL/6J mouse model of hindlimb irradiation using different 10-MV X-ray doses that lead to injuries of different severities. To this end, we first performed broad-spectrum plasma miRNA profiling, followed by a targeted validation step, on two independent animal cohorts. Using a multivariate sparse partial least square discriminant analysis, we identified a panel of eight circulating miRNAs able to segregate mice according to LRI severity. Interestingly, these miRNAs were previously associated with WBI (miR-150-5p, miR-342-3p, miR-146a-5p), inflammation (miR-18a-5p, miR-148b-3p, miR-532-5p) and skin diseases (miR-139-5p, miR-195-5p). Our results suggest the use of circulating miRNAs as suitable molecular biomarkers for LRI prognosis and diagnosis.

Are charged particles a good match for combination with immunotherapy? Current knowledge and perspectives

Charged particle radiotherapy, mainly using protons and carbon ions, provides physical characteristics allowing for a volume conformal irradiation and a reduction of the integral dose to normal tissue. Carbon ion therapy additionally features an increased biological effectiveness resulting in peculiar molecular effects. Immunotherapy, mostly performed with immune checkpoint inhibitors, is nowadays considered a pillar in cancer therapy. Based on the advantageous features of charged particle radiotherapy, we review pre-clinical evidence revealing a strong potential of its combination with immunotherapy. We argue that the combination therapy deserves further investigation with the aim of translation in clinics, where a few studies have been set up already.

Effects of noncoding RNAs in radiotherapy response in breast cancer: a systematic review

Radiotherapy has an essential role in breast cancer treatment. However, tumor cells may be resistant to radiotherapy. Noncoding RNAs are considered regulators of different pathways which modulate radiotherapy. This systematic review classifies long noncoding RNAs, and microRNAs precipitated in the radiation response of breast cancer patients. A total of 14 microRNAs and 8 long noncoding RNAs were studied in this review. MiR-22, miR-200 c, Let7, and LINP1 as tumor suppressors increase the effect of radiotherapy in BC. However, some noncoding RNAs such as HOTAIR, NEAT1, and miR-21 are precipitated in radio-resistance breast cancers. Significant changes in the pattern of noncoding RNAs expression before and after radiotherapy make them a good candidate for the prognosis and prediction of radiotherapy response. MiR-21 and miR-182 can promote radio-resistance via cancer stem cells. At last, the molecular mechanisms initiating radio-resistance were also examined to find the candidate noncoding RNAs for the development of radiation-sensitized agents.

Silent FOSL1 Enhances the Radiosensitivity of Glioma Stem Cells by Down-Regulating miR-27a-5p

Since few reports have mentioned the role of FOSL1 in the radiotherapy sensitivity of glioma, this study would dig deep into this aspect. Cancer stem cells (CSCs) isolated by magnetic bead assay were identified by microscopy, qRT-PCR and western blot. The number of apoptotic cells was counted 72 h after X-ray irradiation to evaluate the sensitivity of cancer cells to radiotherapy. The effects of radiotherapy, FOSL1 and miR-27a-5p on basic cell functions were detected by functional experiments. The expressions of FOSL1, apoptosis-related genes and miR-27a-5p were detected by qRT-PCR and western blot as needed. The differential expression of FOSL1 and the effect of miR-27a-5p on survival rate were analyzed using GEPIA and UALCAN, respectively. FOSL1 was found highly expressed in glioma cells and patients. The appearance of spherical cells and high expressions of CSC-related markers indicated the successful isolation of CSC-like cells. The increment of X-ray dose enhanced the sensitivity of cancer cells to radiotherapy. Radiotherapy down-regulated cell viability and the expressions of FOSL1 and Bcl-2, but up-regulated cell apoptosis and the expressions of cleaved caspase-3 and Bax, which could be partially reversed by overexpressed FOSL1 or further enhanced by shFOSL1. MiR-27a-5p was highly expressed in in patients with glioma, which was associated with poor prognosis, while shFOSL1-inhibited miR-27a-5p expression enhanced the sensitivity of glioma stem cells to radiotherapy. In vivo experiments further verified the results obtained from in vitro experiments. Silent FOSL1 strengthened the radiosensitivity of glioma by down-regulating miR-27a-5p.

The Influence of miRNAs on Radiotherapy Treatment in Prostate Cancer - A Systematic Review

In the last years, extensive investigation on miRNomics have shown to have great advantages in cancer personalized medicine regarding diagnosis, treatment and even clinical outcomes. Prostate cancer (PCa) is the second most common male cancer and about 50% of all PCa patients received radiotherapy (RT), despite some of them develop radioresistance. Here, we aim to provide an overview on the mechanisms of miRNA biogenesis and to discuss the functional impact of miRNAs on PCa under radiation response. As main findings, 23 miRNAs were already identified as being involved in genetic regulation of PCa cell response to RT. The mechanisms of radioresistance are still poorly understood, despite it has been suggested that miRNAs play an important role in cell signaling pathways. Identification of miRNAs panel can be thus considered an upcoming and potentially useful strategy in PCa diagnosis, given that radioresistance biomarkers, in both prognosis and therapy still remains a challenge.

Mutant p53 Mediates Sensitivity to Cancer Treatment Agents in Oesophageal Adenocarcinoma Associated with MicroRNA and SLC7A11 Expression

TP53 gene mutations occur in 70% of oesophageal adenocarcinomas (OACs). Given the central role of p53 in controlling cellular response to therapy we investigated the role of mutant (mut-) p53 and SLC7A11 in a CRISPR-mediated JH-EsoAd1 TP53 knockout model. Response to 2 Gy irradiation, cisplatin, 5-FU, 4-hydroxytamoxifen, and endoxifen was assessed, followed by a TaqMan OpenArray qPCR screening for differences in miRNA expression. Knockout of mut-p53 resulted in increased chemo- and radioresistance (2 Gy survival fraction: 38% vs. 56%, p < 0.0001) and in altered miRNA expression levels. Target mRNA pathways analyses indicated several potential mechanisms of treatment resistance. SLC7A11 knockdown restored radiosensitivity (2 Gy SF: 46% vs. 73%; p = 0.0239), possibly via enhanced sensitivity to oxidative stress. Pathway analysis of the mRNA targets of differentially expressed miRNAs indicated potential involvement in several pathways associated with apoptosis, ribosomes, and p53 signaling pathways. The data suggest that mut-p53 in JH-EsoAd1, despite being classified as non-functional, has some function related to radio- and chemoresistance. The results also highlight the important role of SLC7A11 in cancer metabolism and redox balance and the influence of p53 on these processes. Inhibition of the SLC7A11-glutathione axis may represent a promising approach to overcome resistance associated with mut-p53.

MicroRNA Profiling in Oesophageal Adenocarcinoma Cell Lines and Patient Serum Samples Reveals a Role for miR-451a in Radiation Resistance

Many patients with Oesophageal Adenocarcinoma (OAC) do not benefit from chemoradiotherapy treatment due to therapy resistance. To better understand the mechanisms involved in resistance and to find potential biomarkers, we investigated the association of microRNAs, which regulate gene expression, with the response to individual treatments, focusing on radiation. Intrinsic radiation resistance and chemotherapy drug resistance were assessed in eight OAC cell lines, and miRNA expression profiling was performed via TaqMan OpenArray qPCR. miRNAs discovered were either uniquely associated with resistance to radiation, cisplatin, or 5-FU, or were common to two or all three of the treatments. Target mRNA pathway analyses indicated several potential mechanisms of treatment resistance. miRNAs associated with the in vitro treatment responses were then investigated for association with pathologic response to neoadjuvant chemoradiotherapy (nCRT) in pre-treatment serums of patients with OAC. miR-451a was associated uniquely with resistance to radiation treatment in the cell lines, and with the response to nCRT in patient serums. Inhibition of miR-451a in the radiation resistant OAC cell line OE19 increased radiosensitivity (Survival Fraction 73% vs. 87%, p = 0.0003), and altered RNA expression. Pathway analysis of effected small non-coding RNAs and corresponding mRNA targets suggest potential mechanisms of radiation resistance in OAC.

MED13L integrates Mediator-regulated epigenetic control into lung cancer radiosensitivity

To date, efforts to improve non-small-cell lung cancer (NSCLC) outcomes with increased radiation dose have not been successful. Identification of novel druggable targets that are capable to modulate NSCLC radiosensitivity may provide a way forward. Mediator complex is implicated in gene expression control, but it remains unclear how Mediator dysfunction is involved in cancer radiotherapy.

Methods: The biologic functions of miR-4497, MED13L and PRKCA in NSCLC radiosensitivity were examined through biochemical assays including gene expression profilling, cell proliferation assay, colony formation assay, wound healing assay, transwell assay, dual luciferase reporter assay, xenograft models, immunoprecipitation, and chromatin immunoprecipitation sequencing. Clinical implications of miR-4497, MED13L and PRKCA in radiosensitivity were evaluated in NSCLC patients treated with concurrent chemoradiotherapy or radiotherapy alone.

Results: We found that radiation can trigger disassemble of Mediator complex via silencing of MED13L by miR-4497 in NSCLC. Although not interrupting structure integrity of the core Mediator or the CDK8 kinase module, suppression of MED13L attenuated their physical interactions and reduced recruitment of acetyltransferase P300 to chromatin via Mediator. Silencing of MED13L therefore diminishes global H3K27ac signals written by P300, activities of enhancer and/or promoters and expression of multiple oncogenes, especially PRKCA. Inhibition of PRKCA expression potentiates the killing effect of radiotherapy in vitro and in vivo. Remarkably, high PRKCA expression in NSCLC tissues is correlated with poor prognosis of patients received radiotherapy.

Conclusions: Our study linking PRKCA to radiosensitivity through a novel mechanism may enable the rational targeting of PRKCA to unlock therapeutic potentials of NSCLC.

Impact of accumulated alterations in driver and passenger genes on response to radiation therapy

OBJECTIVE

Although various single genetic factors have been shown to affect radiosensitivity, high-throughput DNA sequencing analyses have revealed complex genomic landscapes in many cancer types. The aim of this study is to elucidate the association between accumulated alterations in driver and passenger genes and radiation therapy response.

METHODS

We used 59 human solid cancer cell lines derived from 11 organ sites. Radiation-induced cell death was measured using a standard colony-forming assay delivered as a single dose ranging from 0 to 12 Gy. Comprehensive genomic data for the cell lines were acquired from the Catalogue Of Somatic Mutations In Cancer v. 80. Random forest classifiers were constructed to predict radioresistant phenotypes using genomic features. The Cancer Genome Atlas data sets were used to evaluate the clinical impact of the genomic feature following radiotherapy.

RESULTS

The 59 cancer cell lines harbored either nucleotide variations or copy number variations in a median of 157 genes per cell. Radiosensitivity of the cancer cells was correlated with neither the number of driver gene mutations nor the number of passenger gene mutations. However, the proportion of driver gene alterations to total gene alterations in gene sets selected from the Kyoto Encyclopedia Genes and Genomes predicted radioresistant cells with sensitivity of 85% and specificity of 73%. High probability of radioresistance predicted by the model was associated with worse overall survival following definitive radiotherapy in patients of The Cancer Genome Atlas data sets.

CONCLUSION

Cellular radiosensitivity was associated with the proportion of driver to total gene alterations in the selected oncogenic pathways, which may be a biomarker candidate for response to radiation therapy.

ADVANCES IN KNOWLEDGE

These findings suggest that accumulated alterations in not only driver genes but also passenger genes affect radiosensitivity.

Non-coding RNA and immune-checkpoint inhibitors: friends or foes?

Non-coding RNAs (ncRNAs) are an abundant component of the human transcriptome. Their biological role, however, remains incompletely understood. Nevertheless, ncRNAs are highly associated with cancer development and progression due to their ability to modulate gene expression, protein translation and growth pathways. Immune-checkpoint inhibitors (ICIs) are considered one of the most promising and highly effective therapeutic approaches for cancer treatment. ICIs are monoclonal antibodies targeting immune checkpoints such as CTLA-4, PD-1 and PD-L1 signalling pathways that stimulate T cell cytotoxicity and can result in tumor growth suppression. This Review will summarize existing knowledge regarding ncRNAs and their role in cancer and ICI therapy. In addition, we will discuss potential mechanisms by which ncRNAs may influence ICI treatment outcomes.

Overexpression of microRNA-145 inhibits tumorigenesis through autophagy in chemotherapy and radiation resistant neuroblastoma cells

MicroRNA-145 (miR-145) plays a suppressive role in the process of tumorigenesis and an important role in induction of autophagy. However, the exact role of miR-145 in therapeutically resistant neuroblastoma cells remain elusive. Herein, we sought to evaluate the effects of miR-145 overexpression in chemo‑ and radiation-resistant neuroblastoma cells. We hypothesized that miR-145 affects the aggressiveness of resistant cells by enhancing autophagy. We established Cisplatin-resistant (CDDP-R), Vincristine-resistant (Vin-R), and radiation-resistant (Rad-R) neuroblastoma cells and found that miR-145 expression was significantly decreased in the resistant cells compared to the parental cells. Exogenously expression of miR-145 inhibited oncogenic properties such as proliferation, clonogenicity, anchorage-independent growth, cell migration, and tubule formation in the resistant cells. In addition, we also found that an autophagy protein marker, LC3, was only minimally expressed in the resistant cells. In particular, when miR-145 was overexpressed in the resistant cells, LC3 I and II were expressed and an increased punctate fluorescence of LC3 protein was found indicating the induction of autophagy. Taken together, our data suggests that miR-145 inhibits tumorigenesis and aggressiveness via modulation of autophagy in neuroblastoma.

The Role of miRNA in the Diagnosis, Prognosis, and Treatment of Osteosarcoma

Osteosarcoma (OS) is one of the most common malignant tumors derived from mesenchymal tissue and is highly invasive, mainly in children and adolescents. Treatment of OS is mostly based on standard treatment options, including aggressive surgical resection, systemic chemotherapy, and targeted radiation therapy, but the 5-year survival rate is still low. MicroRNA (miRNA) is a highly conserved type of endogenous nonprotein-encoding RNA, about 19-25 nucleotides in length, whose transcription process is independent of other genes. Generally, miRNAs play a role in regulating cell proliferation, differentiation, apoptosis, and development by binding to the 3' untranslated region of target mRNAs, whereby they can degrade or induce translational silencing. Although miRNAs play a regulatory role in various metabolic processes, they are not translated into proteins. Several studies have shown that miRNAs play an important role in the diagnosis, treatment, and prognosis of OS. Herein, the authors describe new advances in the diagnosis, prognosis, and treatment of miRNAs in OS.

Noncoding RNAs in cancer therapy resistance and targeted drug development

Noncoding RNAs (ncRNAs) represent a large segment of the human transcriptome and have been shown to play important roles in cellular physiology and disease pathogenesis. Increasing evidence on the functional roles of ncRNAs in cancer progression emphasizes the potential of ncRNAs for cancer treatment. Here, we summarize the roles of ncRNAs in disease relapse and resistance to current standard chemotherapy and radiotherapy; the current research progress on ncRNAs for clinical and/or potential translational applications, including the identification of ncRNAs as therapeutic targets; therapeutic approaches for ncRNA targeting; and ncRNA delivery strategies in potential clinical translation. Several ongoing clinical trials of novel RNA-based therapeutics were also emphasized. Finally, we discussed the perspectives and obstacles to different target combinations, delivery strategies, and system designs for ncRNA application. The next approved nucleic acid drug to treat cancer patients may realistically be on the horizon.

miR-155-5p and miR-760 mediate radiation therapy suppressed malignancy of non-small cell lung cancer cells

MicroRNAs (miRNAs) play important roles in tumorigenesis of various cancers. Recent study suggested that miRNAs are involved in the therapeutic functions of radiation during cancer treatment. We found that radiation can decrease the migration and invasion of non-small cell lung cancer (NSCLC) cells. Mechanistically, radiation can significantly increase the expression of miR-155-5p and miR-760 in NSCLC cells. Knockdown of miR-155-5p and miR-760 can attenuate radiation suppressed proliferation of NSCLC cells. Among the various targets of miR-155-5p, radiation can decrease the expression of HIF-1α. Similarly, radiation can also suppress the expression of IL-6 via a miR-760 dependent pathway. Gain and loss of function studies confirmed that both HIF-1α and IL-6 were involved in the radiation suppressed proliferation of NSCLC cells. Collectively, our data showed that radiation can regulate the expression of miR-155-5p and miR-760 to suppress the malignancy of NSCLC cells. © 2019 BioFactors, 45(3):393-400, 2019.

MicroRNA-mediated redox regulation modulates therapy resistance in cancer cells: clinical perspectives

BACKGROUND

Chemotherapy and radiation therapy are the most common types of cancer therapy. The development of chemo/radio-resistance remains, however, a major obstacle. Altered redox balances are among of the main factors mediating therapy resistance. Therefore, redox regulatory strategies are urgently needed to overcome this problem. Recently, microRNAs have been found to act as major redox regulatory factors affecting chemo/radio-resistance. MicroRNAs play critical roles in regulating therapeutic resistance through the regulation of antioxidant enzymes, redox-sensitive signaling pathways, cancer stem cells, DNA repair mechanisms and autophagy.

CONCLUSIONS

Here, we summarize current knowledge on microRNA-mediated redox regulatory mechanisms underlying chemo/radio-resistance. This knowledge may form a basis for a better clinical management of cancer patients.

miR-339-5p Increases Radiosensitivity of Lung Cancer Cells by Targeting Phosphatases of Regenerating Liver-1 (PRL-1)

BACKGROUND Radiotherapy is the most effective non-surgical modality in lung cancer treatment, and microRNAs (miRNAs) have been suggested as key regulators in radiosensitization. Herein, we explored the specific function of miR-339-5p in the radiosensitivity of lung cancer cells. MATERIAL AND METHODS Radiosensitivity was assessed by cell viability (CCK-8 assay), cell apoptosis, and cell cycle changes (flow cytometry). qRT-PCR and subsequent Western blot assays were used to determine the expression of miR-339-5p and other related proteins. RESULTS We demonstrated that ionizing radiation (IR) exposure impaired lung cancer cell viability, and found that miR-339-5p is a novel IR-inducible miRNA. Overexpression of miR-339-5p enhanced radiosensitivity of A549 and H460 cells by inhibiting cell viability, increasing apoptosis, inducing cell cycle arrest, and suppressing cell proliferation. Further exploration validated that miR-339-5p can target phosphatases of regenerating liver-1  (PRL-1) in lung cancer cells. Restoration of PRL-1 partially reverses the enhanced radiosensitivity of lung cancer cells induced by miR-339-5p. CONCLUSIONS Our data support that miR-339-5p has potential therapeutic value by sensitizing lung cancer cells to radiation via targeting of PRL-1.

Role of miR-142 in the pathogenesis of osteosarcoma and its potential as therapeutic approach

Osteosarcoma (OS) is the most common primary malignant tumor of the bone with a strong tendency to early metastasis, and occurs in growing bones more commonly in children and adolescents. Considering the limited therapeutic methods and lack of 100% success of these methods, developing innovative therapies with high efficacy and lower side effects is needed. Meanwhile, miRNAs and the studies indicating the involvement of miRNAs in OS development have attracted attentions as a result of the frequent abnormalities in expression of miRNAs in cancer. miRNAs are noncoding short sequences with lengths ranging from 18 to 25 nucleotides that play a very important role in cellular processes, such as proliferation, differentiation, migration, and apoptosis. MiRNAs can have either oncogenic or tumor suppressive role based on cellular function and targets. This review aimed to have overview on miR-142 as a tumor suppressor in OS. Moreover, the genes involved in the disease, such as RAC1, HMAG1, MMP9, MMP2, and E-cadherin, which have irregularities as a result of change in miR-142 expression, and, thereby, result in increasing the proliferation, invasion, and metastasis of the cells in the tissues and OS cells will be discussed.

Additional 4-week capecitabine during the resting periods after 6-week neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer: long-term oncologic outcomes

Purpose

The aim of this study was to evaluate the long-term outcome of additional 4-week chemotherapy with capecitabine during the resting periods following a 6-week neoadjuvant chemoradiotherapy (NCRT) regimen, in patients with locally advanced rectal cancer.

Methods

Radiotherapy was delivered to the whole pelvis at a total dose of 50.4 Gy for 6 weeks. Oral capecitabine was administered at a dose of 825 mg/m² twice daily for 10 weeks. Surgery was performed 2–4 weeks following the completion of chemotherapy.

Results

Between January 2010 and September 2011, 41 patients completed the scheduled neoadjuvant therapy and surgery. The pathologic complete response rate, 5-year overall survival, and 5-year disease-free survival rates were 22%, 85.4%, and 78.0%, respectively. The 5-year systemic recurrence and 5-year local recurrence rates were 22% and 0%, respectively.

Conclusion

Additional 4-week chemotherapy with capecitabine, during the resting periods following a 6-week NCRT regimen, has favorable long-term oncologic outcomes. Further randomized controlled trials are however necessary to evaluate if substantial improvement in local control is achieved with this additional chemotherapy modality for locally advanced rectal cancer.

Inhibition of survivin enhances radiosensitivity of esophageal cancer cells by switching radiation-induced senescence to apoptosis

Purpose

Strategies to increase radiosensitivity are urgently needed. Combining radiosensitizing reagents with radiotherapy could improve the outcome of cancer treatment. Some preclinical studies showed that sepantronium bromide (YM155) could sensitize cancer cells to radiation by inhibiting the survivin protein. In this study, we try to investigate the function of YM155 on radiosensitivity of esophageal squamous cell carcinoma (ESCC) cells.

Materials and methods

ESCC cell lines were treated with radiation and YM155, and the radiation efficacy was evaluated by cell counting kit-8 assay and clonogenic survival assay. Cell senescence was measured by senescence-associated β-galactosidase staining. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay, fluorescein isothiocyanate-labeled Annexin V/propidium iodide assay, and poly ADP-ribose polymerase cleavage were used to detect apoptosis. KYSE150 xenografts model was used to test the efficacy of radiation combined with YM155.

Results

YM155 could inhibit the upregulation of survivin induced by radiation in all ESCC cell lines, but the efficacy of radiosensitization varied in different cell lines. Radiation-induced senescence in KYSE150 and KYSE410 cells, and the combination with YM155 inhibited senescence and promoted apoptosis of ESCC cells, thereby enhancing radiosensitivity. Combination with YM155 and radiation delayed the growth of KYSE150 xenografts in nude mice by switching radiation-induced senescence to apoptosis. When p21 was inhibited in KYSE150 cells, radiation did not induce senescence, and the radiosensitization of YM155 was also attenuated. In KYSE510 and KYSE180 cells, radiation did not induce senescence, and YM155 could not enhance the radiosensitivity.

Conclusion

Our results suggest a new mechanism that YM155 might sensitize ESCC cells to radiation by switching radiation-induced senescence to apoptosis. The major determinant of radiosensitization by YM155 might be the induction of senescence by radiation.

microRNA-451a regulates colorectal cancer proliferation in response to radiation

BACKGROUND

Colorectal cancer (CRC) is a leading cause of cancer-related death. The biologic response of CRC to standard of care adjuvant therapies such as chemotherapy and radiation are poorly understood. MicroRNAs (miRs) have been shown to affect CRC progression and metastasis. Therefore, we hypothesized that specific miRs modulate CRC response to chemoradiation.

METHODS

In this study, we used miR expression profiling and discovered a set of microRNAs upregulated rapidly in response to either a single 2 Gy dose fraction or a 10 Gy dose of γ-radiation in mouse colorectal carcinoma models. We used gain and loss-of-function studies in 2D and 3Dcell proliferation assays and colony formation assays to understand the role of the top miR candidate from our profiling. We used Student's T-tests for simple comparisons and two-factor ANOVA for evaluating significance.

RESULTS

The most upregulated candidate at early time points in our signature, miR-451a inhibited tumor cell proliferation and attenuated surviving fraction in longer-term cultures. Conversely, inhibition of miR-451a increased proliferation, tumorsphere formation, and surviving fraction of tumor cells. Using a bioinformatics approach, we identified four genes, CAB39, EMSY, MEX3C, and EREG, as targets of miR-451a. Transfection of miR-451a decreased both mRNA and protein levels of these targets. Importantly, we found miR-451a expression was high and CAB39, EMSY levels were low in a small subset of rectal cancer patients who had a partial response to chemoradiation when compared to patients that had no response. Finally, analysis of a TCGA colorectal cancer dataset revealed that CAB39 and EMSY are upregulated at the protein level in a significant number of CRC patients. Higher levels of CAB39 and EMSY correlated with poorer overall survival.

CONCLUSIONS

Taken together, our data indicates miR-451a is induced by radiation and may influence colorectal carcinoma proliferation via CAB39 and EMSY pathways.

miR-144-5p Enhances the Radiosensitivity of Non-Small-Cell Lung Cancer Cells via Targeting ATF2

MicroRNAs (miRNAs or miRs) regulate gene expression at the posttranscriptional level and are involved in many biological processes such as cell proliferation and migration, stem cell differentiation, inflammation, and apoptosis. In particular, miR-144-3p is downregulated in various cancers, and its overexpression inhibits the proliferation and metastasis of cancer cells. However, the role of miR-144-5p in non-small-cell lung cancer (NSCLC), especially radiosensitivity, is unknown. In this study, we found that miR-144-5p was downregulated in NSCLC clinical specimens as well as NSCLC cell lines exposed to radiation. Enhanced expression of miR-144-5p promoted the radiosensitivity of NSCLC cells in vitro and A549 cell mouse xenografts in vivo. Furthermore, we identified activating transcription factor 2 (ATF2) as the direct and functional target of miR-144-5p using integrated bioinformatics analysis and a luciferase reporter assay. In addition, restoration of ATF2 expression inhibited miR-144-5p-induced NSCLC cell sensitivity to radiation in vitro and in vivo. Our findings suggest that deregulation of the miR-144-5p/ATF2 axis plays an important role in NSCLC cell radiosensitivity, thus representing a new potential therapeutic target for NSCLC.

What Is New in the miRNA World Regarding Osteosarcoma and Chondrosarcoma?

Despite the availability of multimodal and aggressive therapies, currently patients with skeletal sarcomas, including osteosarcoma and chondrosarcoma, often have a poor prognosis. In recent decades, advances in sequencing technology have revealed the presence of RNAs without coding potential known as non-coding RNAs (ncRNAs), which provides evidence that protein-coding genes account for only a small percentage of the entire genome. This has suggested the influence of ncRNAs during development, apoptosis and cell proliferation. The discovery of microRNAs (miRNAs) in 1993 underscored the importance of these molecules in pathological diseases such as cancer. Increasing interest in this field has allowed researchers to study the role of miRNAs in cancer progression. Regarding skeletal sarcomas, the research surrounding which miRNAs are involved in the tumourigenesis of osteosarcoma and chondrosarcoma has rapidly gained traction, including the identification of which miRNAs act as tumour suppressors and which act as oncogenes. In this review, we will summarize what is new regarding the roles of miRNAs in chondrosarcoma as well as the latest discoveries of identified miRNAs in osteosarcoma.

Profiling of a panel of radioresistant prostate cancer cells identifies deregulation of key miRNAs

Background

miRNAs are increasingly associated with the aggressive phenotype of prostate tumours. Their ability to control radiobiologically-relevant cellular processes strengthens their potential as novel markers of response to radiation therapy.

Purpose

To identify miRNAs associated with increased clonogenic survival following radiation exposure.

Material and methods

The miRNA expression profiles of a panel of 22RV1 cells with varying levels of radiosensitivities (hypoxic H-22Rv1 cells, RR-22Rv1 cells derived from WT-22Rv1 cells through 2-Gy fractionated repeated exposure, the associated aged matched cells (AMC-22Rv1) and the WT-22Rv1 cell lines) were generated and cross-analysed to identify common miRNAs associated with a radioresistant phenotype.

Results

Increased clonogenic survival following irradiation was associated with significant modifications in miRNA expression pattern. miR-221 (up) and miR-4284 (down) in RR-22Rv1 and MiR-31 and miR-200c in AMC-22Rv1 were the most uniquely significantly deregulated miRNAs when compared to WT-22Rv1 cells. miR-200c ranked as the most downregulated miRNAs in hypoxic, when compared to RR-22Rv1 cells. miR-200a was the only differentially expressed miRNA between RR-22Rv1 and AMC-22Rv1 cells. miR-210 yielded the highest fold change in expression in H-22Rv1, when compared to WT-22RV1 cells.

Conclusion

This study identifies candidate miRNAs for the development of novel prognostic biomarkers for radiotherapy prostate cancer patients.