Novel Epigenetic CREB-miR-630 Signaling Axis Regulates Radiosensitivity in Colorectal Cancer

miR-1226-5p is involved in radioresistance of colorectal cancer by activating M2 macrophages through suppressing IRF1

BACKGROUND

Although the representative treatment for colorectal cancer (CRC) is radiotherapy, cancer cells survive due to inherent radioresistance or resistance acquired after radiation treatment, accelerating tumor malignancy and causing local recurrence and metastasis. However, the detailed mechanisms of malignancy induced after radiotherapy are not well understood. To develop more effective and improved radiotherapy and diagnostic methods, it is necessary to clearly identify the mechanisms of radioresistance and discover related biomarkers.

METHODS

To analyze the expression pattern of miRNAs in radioresistant CRC, sequence analysis was performed in radioresistant HCT116 cells using Gene Expression Omnibus, and then miR-1226-5p, which had the highest expression in resistant cells compared to parental cells, was selected. To confirm the effect of miR-1226-5 on tumorigenicity, Western blot, qRT-PCR, transwell migration, and invasion assays were performed to confirm the expression of EMT factors, cell mobility and invasiveness. Additionally, the tumorigenic ability of miR-1226-5p was confirmed in organoids derived from colorectal cancer patients. In CRC cells, IRF1, a target gene of miR-1226-5p, and circSLC43A1, which acts as a sponge for miR-1226-5p, were discovered and the mechanism was analyzed by confirming the tumorigenic phenotype. To analyze the effect of tumor-derived miR-1226-5p on macrophages, the expression of M2 marker in co-cultured cells and CRC patient tissues were confirmed by qRT-PCR and immunohistochemical (IHC) staining analyses.

RESULTS

This study found that overexpressed miR-1226-5p in radioresistant CRC dramatically promoted epithelial-mesenchymal transition (EMT), migration, invasion, and tumor growth by suppressing the expression of its target gene, IRF1. Additionally, we discovered circSLC43A1, a factor that acts as a sponge for miR-1226-5p and suppresses its expression, and verified that EMT, migration, invasion, and tumor growth are suppressed by circSLC43A1 in radioresistant CRC cells. Resistant CRC cells-derived miR-1226-5p was transferred to macrophages and contributed to tumorigenicity by inducing M2 polarization and secretion of TGF-β.

CONCLUSIONS

This study showed that the circSLC43A1/miR-1226-5p/IRF1 axis is involved in radioresistance and cancer aggressiveness in CRC. It was suggested that the discovered signaling factors could be used as potential biomarkers for diagnosis and treatment of radioresistant CRC.

Network-based elucidation of colon cancer drug resistance mechanisms by phosphoproteomic time-series analysis

Aberrant signaling pathway activity is a hallmark of tumorigenesis and progression, which has guided targeted inhibitor design for over 30 years. Yet, adaptive resistance mechanisms, induced by rapid, context-specific signaling network rewiring, continue to challenge therapeutic efficacy. Leveraging progress in proteomic technologies and network-based methodologies, we introduce Virtual Enrichment-based Signaling Protein-activity Analysis (VESPA)-an algorithm designed to elucidate mechanisms of cell response and adaptation to drug perturbations-and use it to analyze 7-point phosphoproteomic time series from colorectal cancer cells treated with clinically-relevant inhibitors and control media. Interrogating tumor-specific enzyme/substrate interactions accurately infers kinase and phosphatase activity, based on their substrate phosphorylation state, effectively accounting for signal crosstalk and sparse phosphoproteome coverage. The analysis elucidates time-dependent signaling pathway response to each drug perturbation and, more importantly, cell adaptive response and rewiring, experimentally confirmed by CRISPR knock-out assays, suggesting broad applicability to cancer and other diseases.

Role of non-coding RNAs as new therapeutic targets in regulating the EMT and apoptosis in metastatic gastric and colorectal cancers

Colorectal cancer (CRC) and gastric cancer (GC), are the two most common cancers of the gastrointestinal tract, and are serious health concerns worldwide. The discovery of more effective biomarkers for early diagnosis, and improved patient prognosis is important. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), can regulate cellular processes such as apoptosis and the epithelial-mesenchymal transition (EMT) leading to progression and resistance of GC and CRC tumors. Moreover these pathways (apoptosis and EMT) may serve as therapeutic targets, to prevent metastasis, and to overcome drug resistance. A subgroup of ncRNAs is common to both GC and CRC tumors, suggesting that they might be used as biomarkers or therapeutic targets. In this review, we highlight some ncRNAs that can regulate EMT and apoptosis as two opposite mechanisms in cancer progression and metastasis in GC and CRC. A better understanding of the biological role of ncRNAs could open up new avenues for the development of personalized treatment plans for GC and CRC patients.

Role of microRNAs in regulation of doxorubicin and paclitaxel responses in lung tumor cells

Lung cancer as the leading cause of cancer related mortality is always one of the main global health challenges. Despite the recent progresses in therapeutic methods, the mortality rate is still significantly high among lung cancer patients. A wide range of therapeutic methods including chemotherapy, radiotherapy, and surgery are used to treat lung cancer. Doxorubicin (DOX) and Paclitaxel (TXL) are widely used as the first-line chemotherapeutic drugs in lung cancer. However, there is a significant high percentage of DOX/TXL resistance in lung cancer patients, which leads to tumor recurrence and metastasis. Considering, the side effects of these drugs in normal tissues, it is required to clarify the molecular mechanisms of DOX/TXL resistance to introduce the efficient prognostic and therapeutic markers in lung cancer. MicroRNAs (miRNAs) have key roles in regulation of different pathophysiological processes including cell division, apoptosis, migration, and drug resistance. MiRNA deregulations are widely associated with chemo resistance in various cancers. Therefore, considering the importance of miRNAs in chemotherapy response, in the present review, we discussed the role of miRNAs in regulation of DOX/TXL response in lung cancer patients. It has been reported that miRNAs mainly induced DOX/TXL sensitivity in lung tumor cells by the regulation of signaling pathways, autophagy, transcription factors, and apoptosis. This review can be an effective step in introducing miRNAs as the non-invasive prognostic markers to predict DOX/TXL response in lung cancer patients.

A Systems Biology Approach to Identify Novel Biomarkers in Progression from Crohn's Disease to Colorectal Cancer

OBJECTIVE

This study aimed to find the key genes and miRNAs as potential biomarkers related to the progression of colorectal cancer (CRC) from Crohn's disease (CD).

BACKGROUND

CD is widely accepted as one of the main risk factors leading to CRC. So, Identifying the novel molecular pathways involved in the development of CRC from CD can provide potential solutions for therapeutic interventions.

METHODS

By implementing a systematic approach, we have analyzed mRNA and miRNA datasets containing CRC and CD samples to determine differentially expressed genes (DEGs) and miRNAs (DEmiRNA). Then by selecting common genes involved in the progression from CD to CRC, different downstream analyses including mRNA-miRNA network, functional enrichment analysis, gene set enrichment analysis, and survival analysis were performed. Finally, quantitative real-time PCR (RT-PCR) analysis of tissue samples obtained from Normal/CRC samples was used to confirm the differential expression of selected genes and miRNA.

RESULTS

There were 10 DE miRNA and 181 genes DEGs common between progression from CD to CRC. The genes obtained for each of the 10 miRNAs were considered as the final target for downstream analyzes. In addition, analysis of RT-PCR indicated that miR-195-5p, PHLPP2, and LITAF   were downregulated in the cancer group compared to the control group.

CONCLUSION

This study showed that PHLPP2, LITAF, and miR-195-5p may have key roles in the tumorigenesis of CRC and they can be used as therapeutic targets and diagnostic biomarkers after further in-vitro and in-vivo evaluation.

Network-based elucidation of colon cancer drug resistance by phosphoproteomic time-series analysis

Aberrant signaling pathway activity is a hallmark of tumorigenesis and progression, which has guided targeted inhibitor design for over 30 years. Yet, adaptive resistance mechanisms, induced by rapid, context-specific signaling network rewiring, continue to challenge therapeutic efficacy. By leveraging progress in proteomic technologies and network-based methodologies, over the past decade, we developed VESPA-an algorithm designed to elucidate mechanisms of cell response and adaptation to drug perturbations-and used it to analyze 7-point phosphoproteomic time series from colorectal cancer cells treated with clinically-relevant inhibitors and control media. Interrogation of tumor-specific enzyme/substrate interactions accurately inferred kinase and phosphatase activity, based on their inferred substrate phosphorylation state, effectively accounting for signal cross-talk and sparse phosphoproteome coverage. The analysis elucidated time-dependent signaling pathway response to each drug perturbation and, more importantly, cell adaptive response and rewiring that was experimentally confirmed by CRISPRko assays, suggesting broad applicability to cancer and other diseases.

Insights into the radiotherapy-induced deferentially expressed RNAs in colorectal cancer management

Radiotherapy (RT) has been commonly applied to treat advanced local cancers. In radiation therapy, high doses of radiation are utilized to trigger cell death. Radiation often leads to DNA double-strand breakages (DSB), which causes the activation of downstream genes including those for non-coding RNAs (ncRNA) such as long non-coding and RNAsmicro RNAs. The consequence of RT significantly relies on the radiosensitivity of cancer cells, which is affected by multiple factors, including some proteins and cellular processes. Activation of these genes can cause cell cytotoxicity and indirectly damages the cells. Recent studies have shown that non-coding RNAs can play as radiosensitivity or radioinhibitory regulators in cancers by mechanisms such as cell cycle arrest or affecting the DNA damage repair systems. ncRNAs are also known to function as tumor suppressor genes or oncogenes in colorectal cancer and therefore are considered potential diagnostic biomarkers in disease detection. For example, the investigations have shown that miR-29a and miR-224 can be informative biomarkers for early detection or screening of CRC via a noninvasive method such as liquid biopsy. Here, we discuss ncRNAs involved in the radioresistance and radiosensitivity of CRC and highlight their predictive clinical value in response to RT. Accordingly, this review represents a principal guide in the context of three major types of ncRNAs with potential roles in the pathway of radiosensitivity and radioresistance, including miRNAs, lncRNAs, and circRNAs which can be considered a precious archivement in organizing additional studies and broadening views in this area. Our findings can also assist radiotherapists in predicting CRC patients' response and, therefore, prognosis to radiation therapy, although, to achieve our goals in the clinic, we certainly need further studies.

Mechanisms of microRNA action in rectal cancer radiotherapy

ABSTRACT

Preoperative neoadjuvant chemoradiotherapy, combined with total mesorectal excision, has become the standard treatment for advanced localized rectal cancer (RC). However, the biological complexity and heterogeneity of tumors may contribute to cancer recurrence and metastasis in patients with radiotherapy-resistant RC. The identification of factors leading to radioresistance and markers of radiosensitivity is critical to identify responsive patients and improve radiotherapy outcomes. MicroRNAs (miRNAs) are small, endogenous, and noncoding RNAs that affect various cellular and molecular targets. miRNAs have been shown to play important roles in multiple biological processes associated with RC. In this review, we summarized the signaling pathways of miRNAs, including apoptosis, autophagy, the cell cycle, DNA damage repair, proliferation, and metastasis during radiotherapy in patients with RC. Also, we evaluated the potential role of miRNAs as radiotherapeutic biomarkers for RC.

The Roles of Non-Coding RNAs in Radiotherapy of Gastrointestinal Carcinoma

Radiotherapy (RT), or radiation therapy, has been widely used in clinical practice for the treatment of local advanced gastrointestinal carcinoma. RT causes DNA double-strand breaks leading to cell cytotoxicity and indirectly damages tumor cells by activating downstream genes. Non-coding RNA (including microRNAs, long non-coding RNAs (ncRNAs), and circular RNAs) is a type of RNA that does not encode a protein. As the field of ncRNAs increasingly expands, new complex roles have gradually emerged for ncRNAs in RT. It has been shown that ncRNAs can act as radiosensitivity regulators in gastrointestinal carcinoma by affecting DNA damage repair, cell cycle arrest, irradiation-induced apoptosis, cell autophagy, stemness, EMT, and cell pyroptosis. Here, we review the complex roles of ncRNAs in RT and gastrointestinal carcinoma. We also discuss the potential clinical significance and predictive value of ncRNAs in response to RT for guiding the individualized treatment of patients. This review can serve as a guide for the application of ncRNAs as radiosensitivity enhancers, radioresistance inducers, and predictors of response in RT of gastrointestinal carcinoma.

The importance of miRNA-630 in human diseases with an especial focus on cancers

miR-630 is encoded by MIR630 gene (NC_000015.10) on 15q24.1. This miRNA is mostly associated with cytokine signaling in immune system. Several neoplastic as well as non-neoplastic conditions have been linked with dysregulation of miR-630. It is an oncogenic miRNA in renal cell carcinoma, multiple myeloma, colorectal cancer, acute lymphoblastic leukemia, ovarian cancer and prostate cancer. On the other hand, it is a putative tumor suppressor miRNA in lung, cervical, breast, thyroid and esophageal tissues. In a number of other tissues, data regarding the role of miR-630 in the carcinogenesis is conflicting. Expression levels of miR-630 can be used as markers for prediction of cancer course. Moreover, miR-630 can influence response to chemoradiotherapy. This miRNA is also involved in the pathoetiology of IgA nephropathy, obstructive sleep apnea, age-related nuclear cataract and vitiligo. In the present review, we discuss the role of miR-630 in these conditions.

miRNA-31 increases radiosensitivity through targeting STK40 in colorectal cancer cells

Objective

To propose and verify that miRNA‐31 increases the radiosensitivity of colorectal cancer and explore its potential mechanism.

Method

A bioinformatics analysis was performed to confirm that the expression of miRNA‐31 was higher in colorectal cancer than in normal colorectal tissue. The expression of miRNA‐31 was detected to verify the change in its expression in a radiotherapy‐resistant cell line. Methylation was detected to explore the cause of the decrease in miRNA‐31 expression. Overexpression or inhibition of miRNA‐31 further confirmed the change in its expression in colorectal cancer cell lines. Bioinformatics methods were used to screen the downstream target genes and for experimental verification. A luciferase assay was performed to determine the miRNA‐31 binding site in STK40. Overexpression or inhibition of STK40 in colorectal cancer cell lines further confirmed the change in STK40 expression in vitro.

Results

The bioinformatics results showed higher expression of miRNA‐31 in tumors than in normal tissue, and miRNA‐31 mainly participated in the pathway related to cell replication. Next, we observed the same phenomenon: miRNA‐31 was expressed at higher levels in colorectal tumors than in normal colorectal tissue and its expression decreased in radiation‐resistant cell lines after radiation, implying that miRNA‐31 increased the radiosensitivity of colorectal cancer cell lines. No significant change in upstream methylation was observed. miRNA‐31 regulated the radiosensitivity of colorectal cancer cell lines by inhibiting STK40. Notably, miRNA‐31 played a role by binding to the 3′ untranslated region of SK40. STK40 negatively regulated the radiosensitivity of colorectal cancer cells.

Conclusions

miRNA‐31 increases the radiosensitivity of colorectal cancer cells by targeting STK40; miRNA‐31 and STK40 are expected to become potential biomarkers for increasing the sensitivity of tumor radiotherapy in clinical treatment.

MicroRNAs and Apoptosis in Colorectal Cancer

Colorectal cancer (CRC) is the third leading cause of cancer death in the world, and its incidence is rising in developing countries. Treatment with 5-Fluorouracil (5-FU) is known to improve survival in CRC patients. Most anti-cancer therapies trigger apoptosis induction to eliminate malignant cells. However, de-regulated apoptotic signaling allows cancer cells to escape this signaling, leading to therapeutic resistance. Treatment resistance is a major challenge in the development of effective therapies. The microRNAs (miRNAs) play important roles in CRC treatment resistance and CRC progression and apoptosis. This review discusses the role of miRNAs in contributing to the promotion or inhibition of apoptosis in CRC and the role of miRNAs in modulating treatment resistance in CRC cells.

BCL-w: apoptotic and non-apoptotic role in health and disease

The BCL-2 family of proteins integrates signals that trigger either cell survival or apoptosis. The balance between pro-survival and pro-apoptotic proteins is important for tissue development and homeostasis, while impaired apoptosis contributes to several pathologies and can be a barrier against effective treatment. BCL-w is an anti-apoptotic protein that shares a sequence similarity with BCL-X_L, and exhibits a high conformational flexibility. BCL-w level is controlled by a number of signaling pathways, and the repertoire of transcriptional regulators largely depends on the cellular and developmental context. As only a few disease-relevant genetic alterations of BCL2L2 have been identified, increased levels of BCL-w might be a consequence of abnormal activation of signaling cascades involved in the regulation of BCL-w expression. In addition, BCL-w transcript is a target of a plethora of miRNAs. Besides its originally recognized pro-survival function during spermatogenesis, BCL-w has been envisaged in different types of normal and diseased cells as an anti-apoptotic protein. BCL-w contributes to survival of senescent and drug-resistant cells. Its non-apoptotic role in the promotion of cell migration and invasion has also been elucidated. Growing evidence indicates that a high BCL-w level can be therapeutically relevant in neurodegenerative disorders, neuron dysfunctions and after small intestinal resection, whereas BCL-w inhibition can be beneficial for cancer patients. Although several drugs and natural compounds can bi-directionally affect BCL-w level, agents that selectively target BCL-w are not yet available. This review discusses current knowledge on the role of BCL-w in health, non-cancerous diseases and cancer.

miR-183-5p enhances the radioresistance of colorectal cancer by directly targeting ATG5

Radioresistance is a material obstacle for effective treatment of colorectal cancer (CRC). Thus, the discovery of a novel biomarker for determining the CRC radiosensitivity is necessary. Recent studies have confirmed that miR-183-3p regulates cell phenotypes and tumor growth in various cancers. However, the role and mechanism of this micro-ribonucleic acid in CRC radiosensitivity remains unclear. Here, the abundances of miR-183-5p and ATG5 mRNAwere detected by a real-time quantitative reverse transcription polymerase chain reaction. Kaplan-Meier survival analysis was carried out to explore the correlation between miR-183-5p and patient prognosis. Cell viability was evaluated by the MTT assay. Survival fraction analysis through colony formation was performed to assess the cell radiation response. Bioinformatic, luciferase and western blot assays were employed to verify the targeted interaction between miR-183-5p and ATG5. The results showed that an elevated abundance of miR-183-5p and a reduced ATG5 level in CRC were associated with the poor prognosis. The knockdown of miR-183-5p enhanced the sensitivity of CRC cells to radiation, inflected by the decreased cell viability and survival fraction. Mechanically, ATG5 was targeted by miR-183-5p. The addition of ATG5 conferred the radiosensitivity of the CRC cells, which was revered by miR-183-5p restoration. Furthermore, miR-183-5p knockdown hindered the tumor growth by repressing ATG5 in vivo after radiation treatment. In summary, the output data indicated that miR-183-5p heightened the radiation response of the CRC cells by targeting ATG5, promising a novel therapeutic target for CRC patients with radioresistance.

Downregulated microRNAs in the colorectal cancer: diagnostic and therapeutic perspectives

Colorectal cancer (CRC), the third most common cancer in the world, has no specific biomarkers that facilitate its diagnosis and subsequent treatment. The miRNAs, small single-stranded RNAs that repress the mRNA translation and trigger the mRNA degradation, show aberrant levels in the CRC, by which these molecules have been related with the initiation, progression, and drug-resistance of this cancer type. Numerous studies show the microRNAs influence the cellular mechanisms related to the cell cycle, differentiation, apoptosis, and migration of the cancer cells through the post-transcriptionally regulated gene expression. Specific patterns of the upregulated and down-regulated miRNA have been associated with the CRC diagnosis, prognosis, and therapeutic response. Concretely, the downregulated miRNAs represent attractive candidates, not only for the CRC diagnosis, but for the targeted therapies via the tumor-suppressing microRNA replacement. This review shows a general overview of the potential uses of the miRNAs in the CRC diagnosis, prognosis, and treatment with a special focus on the downregulated ones. [BMB Reports 2018; 51(11): 563-571].

Tumour necrosis factor-α-induced protein 8-like 2 is a novel regulator of proliferation, migration, and invasion in human rectal adenocarcinoma cells

Tumour necrosis factor‐α‐induced protein 8‐like 2 (TIPE2) is a tumour suppressor in many types of cancer. However, the mechanism of action of TIPE2 on the growth of rectal adenocarcinoma is unknown. Our results showed that the expression levels of TIPE2 in human rectal adenocarcinoma tissues were higher than those in adjacent non‐tumour tissues. Overexpression of TIPE2 reduced the proliferation, migration, and invasion of human rectal adenocarcinoma cells and down‐regulation of TIPE2 showed reverse effects. TIPE2 overexpression increased apoptosis through down‐regulating the expression levels of Wnt3a, phospho (p)‐β‐Catenin, and p‐glycogen synthase kinase‐3β in rectal adenocarcinoma cells, however, TIPE2 knockdown exhibited reverse trends. TIPE2 overexpression decreased autophagy by reducing the expression levels of p‐Smad2, p‐Smad3, and transforming growth factor‐beta (TGF‐β) in rectal adenocarcinoma cells, however, TIPE2 knockdown showed opposite effects. Furthermore, TIPE2 overexpression reduced the growth of xenografted human rectal adenocarcinoma, whereas TIPE2 knockdown promoted the growth of rectal adenocarcinoma tumours by modulating angiogenesis. In conclusion, TIPE2 could regulate the proliferation, migration, and invasion of human rectal adenocarcinoma cells through Wnt/β‐Catenin and TGF‐β/Smad2/3 signalling pathways. TIPE2 is a potential therapeutic target for the treatment of rectal adenocarcinoma.

Differential miRNA expression profiling reveals miR-205-3p to be a potential radiosensitizer for low- dose ionizing radiation in DLD-1 cells

Enhanced radiosensitivity at low doses of ionizing radiation (IR) (0.2 to 0.6 Gy) has been reported in several cell lines. This phenomenon, known as low doses hyper-radiosensitivity (LDHRS), appears as an opportunity to decrease toxicity of radiotherapy and to enhance the effects of chemotherapy. However, the effect of low single doses IR on cell death is subtle and the mechanism underlying LDHRS has not been clearly explained, limiting the utility of LDHRS for clinical applications. To understand the mechanisms responsible for cell death induced by low-dose IR, LDHRS was evaluated in DLD-1 human colorectal cancer cells and the expression of 80 microRNAs (miRNAs) was assessed by qPCR array. Our results show that DLD-1 cells display an early DNA damage response and apoptotic cell death when exposed to 0.6 Gy. miRNA expression profiling identified 3 over-expressed (miR-205-3p, miR-1 and miR-133b) and 2 down-regulated miRNAs (miR-122-5p, and miR-134-5p) upon exposure to 0.6 Gy. This miRNA profile differed from the one in cells exposed to high-dose IR (12 Gy), supporting a distinct low-dose radiation-induced cell death mechanism. Expression of a mimetic miR-205-3p, the most overexpressed miRNA in cells exposed to 0.6 Gy, induced apoptotic cell death and, more importantly, increased LDHRS in DLD-1 cells. Thus, we propose miR-205-3p as a potential radiosensitizer to low-dose IR.

CircRNA_100269 is downregulated in gastric cancer and suppresses tumor cell growth by targeting miR-630

Although CircRNA_100269 is a biomarker used to predict cancer recurrence, its expression and function in gastric cancer (GC) remain unknown. In this study, the expression of circRNA_100269 and its potential downstream miRNA targets were investigated. The molecular function and regulatory mechanism of circRNA_100269 in GC cell lines were also elucidated. The expression levels of circRNA_100269 and its linear isomer LPHN2 mRNA were found to be downregulated (p<0.01) in GC tissues. The target miRNA was predicted to be miR-630, whose expression was upregulated (p<0.01) and found to be negatively correlated with that of circRNA_100269 (r = −0.688) in GC tissues. Moreover, direct interaction of circRNA_100269 and miR-630 was confirmed through dual-luciferase assays. Overexpressing the circRNA_100269 plasmid inhibited cell proliferation (p<0.05). Furthermore, transfection of miR-630 mimics into cell lines overexpressing circRNA_100269 blocked the function of circRNA_100269 (p<0.05). Thus, circRNA_100269 level was downregulated in GC and correlated negatively with that of miR-630. Taken together, our results suggest that circRNA_100269 and miR-630 comprise a novel pathway that regulates proliferation of GC cells.

Role of microRNAs in the resistance of colorectal cancer to chemoradiotherapy

Colorectal cancer (CRC) is among the main tumor-related causes of death worldwide. The fact that the majority of the patients develop resistance to chemoradiotherapy (CRT) is a major obstacle for the treatment of CRC. In order to develop more effective treatment strategies, it is crucial to elucidate the mechanisms underlying the development of resistance to CRT. Several studies have recently indicated the regulatory effects of microRNAs (miRNAs) in response to antitumor agents. For example, miR-34a attenuates the chemoresistance of colon cancer to 5-FU by inhibiting E2F3 and SIRT1. The miR-34a mimic MRX34 is the first synthetic miRNA to have been entered into clinical trials. miR-21 prevents tumor cell stemness, invasion and drug resistance, which are required for the development of CRC. These findings suggest that miRNAs represent a focus in the research of novel cancer treatments aimed at sensitizing cancer cells to chemotherapeutic drugs. The aim of the present study was to review the functions of miRNAs and investigate the roles of miRNAs in CRC radioresistance or chemoresistance. Furthermore, the potential of including miRNAs in therapeutic strategies and using them as molecular biomarkers for predicting radiosensitivity and chemosensitivity was discussed.

MiRNA-107 enhances chemosensitivity to paclitaxel by targeting antiapoptotic factor Bcl-w in non small cell lung cancer

The aim of this study is to elucidate whether and how miR-107 participates in the modulation of paclitaxel sensitivity in non small cell lung cancer (NSCLC). By qRT-PCR, we found that miR-107 is significantly down-regulated in paclitaxel-resistant A549/Taxol cells compared with corresponding paclitaxel-sensitive counterparts. Overexpression of miR-107 suppresses paclitaxel resistance of A549/Taxol cells through directly inhibiting Bcl-w. Overexpression of miR-107 promotes apoptosis and inhibits proliferation and mobility of A549/Taxol cells under treatment with paclitaxel in vitro. Moreover, miR-107 inhibits in vivo paclitaxel resistance in xenograft model. MiR-107/Bcl-w axis regulates paclitaxel chemoresistance through PI3K-Akt pathway. Our results suggest that up-regulation of miR-107 resensitizes paclitaxel-resistant NSCLC cells by targeting Bcl-w, which reveals a potential mechanism of miR-107 in reversing drug resistance.

Molecular profiling of locally-advanced rectal adenocarcinoma using microRNA expression (Review)

Treatment for locally-advanced rectal cancer (LARC) typically consists of neoadjuvant chemoradiation followed by total mesorectal excision. Recently, there has been growing interest in non-operative management for patients who are medically-inoperable or wish to avoid surgical morbidity and permanent colostomy. Approximately 50% of patients who receive pre-operative neoadjuvant chemoradiation develop some degree of pathologic response. Approximately 10-20% of patients are found to have a complete pathologic response, a finding which has frequently been shown to predict better clinical outcomes, including local-regional control, distant metastasis and survival. Many recent studies have evaluated the role of molecular biomarkers in predicting response to neoadjuvant therapy. MicroRNAs (miRNAs) are an emerging class of biomarkers that have the potential to predict which patients are most likely to benefit from pre-operative therapy and from a selective surgical approach. Here, we review the published literature on microRNAs as prognostic and predictive biomarkers in rectal cancer after pre-operative therapy. In the future, the development of prospectively validated miRNA signatures will allow clinical implementation of miRNAs as prognostic and predictive signatures in LARC.

Colorectal Cancer: From the Genetic Model to Posttranscriptional Regulation by Noncoding RNAs

Colorectal cancer is the third most common form of cancer in developed countries and, despite the improvements achieved in its treatment options, remains as one of the main causes of cancer-related death. In this review, we first focus on colorectal carcinogenesis and on the genetic and epigenetic alterations involved. In addition, noncoding RNAs have been shown to be important regulators of gene expression. We present a general overview of what is known about these molecules and their role and dysregulation in cancer, with a special focus on the biogenesis, characteristics, and function of microRNAs. These molecules are important regulators of carcinogenesis, progression, invasion, angiogenesis, and metastases in cancer, including colorectal cancer. For this reason, miRNAs can be used as potential biomarkers for diagnosis, prognosis, and efficacy of chemotherapeutic treatments, or even as therapeutic agents, or as targets by themselves. Thus, this review highlights the importance of miRNAs in the development, progression, diagnosis, and therapy of colorectal cancer and summarizes current therapeutic approaches for the treatment of colorectal cancer.

Inhibition of miR-630 enhances the cell resistance to radiation by directly targeting CDC14A in human glioma

Radio-resistance becomes a large obstacle for effective cancer treatment. MicroRNAs (miRNAs) play important roles in response to radiation. However, the underlying mechanism of miR-630 on the radio-resistance of human glioma is less elucidated. In this study, we found that miR-630 was downregulated in glioma cell lines after radiation. MiR-630 inhibition enhanced the survival fraction, cell number in S stage and colony formation ability in glioma cells after radiation, while miR-630 overexpression resulted in inverse effects. By detecting the molecular mechanism of miR-630, we validated that CDC14A was a direct target of miR-630 and miR-630 suppressed CDC14A protein level. CDC14A overexpression can attenuate the inhibitory roles of miR-630 in survival fraction and cell proliferation. Finally, in vivo study demonstrated that miR-630 inhibition increased the volumes of xenografts bearing with glioma cells after radiation. In conclusion, our data indicate that anti-miR-630 enhances the radio-resistance of human glioma cells by targeting CDC14A, implying that miR-630 may act as a novel therapeutic target for enhancing the radiation efficiency on glioma patients.

miR-195 enhances the radiosensitivity of colorectal cancer cells by suppressing CARM1

BACKGROUND

microRNAs (miRNAs) can regulate the sensitivity of cancer cells to chemotherapy and radiotherapy. Aberrant expression of miR-195 has been found to be involved in colorectal cancer (CRC); however, its function and underlying mechanism in the radioresistance of CRC remains unclear.

METHODS

The levels of miR-195 and CARM1 were detected by quantitative reverse transcription-polymerase chain reaction and Western blot analysis in HCT-116 and HT-29 cells, respectively. Colony survival and apoptosis were determined by clonogenic assay and flow cytometry analysis, respectively. The apoptosis-related proteins Bax, Bcl-2, and γ-H2AX were detected using Western blot. The targets of miR-195 were identified by bioinformatic prediction and luciferase reporter assays. CRC cells in vitro and in vivo were exposed to different doses of X-ray radiations.

RESULTS

miR-195 was downregulated, and CARM1 was upregulated in HCT-116 and HT-29 cells. miR-195 overexpression or CARM1 knockdown suppressed colony survival, induced apoptosis, promoted expression of Bax and γ-H2AX, and inhibited Bcl-2 expression in CRC cells. CARM1 was identified and validated to be a functional target of miR-195. Moreover, restored expression of CARM1 reversed the enhanced radiosensitivity of CRC cells induced by miR-195. Furthermore, miR-195 increased the sensitivity of CRC cells to radiation in vivo.

CONCLUSION

miR-195 enhances radiosensitivity of CRC cells through suppressing CARM1. Therefore, miR-195 acts as a potential regulator of radioresistance for CRC cells and as a promising therapeutic target for CRC patients.

MiR-630 inhibits invasion and metastasis in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is among the most aggressive malignancies and has a high incidence in China. MicroRNAs (miRNAs) are small endogenous RNAs that regulate multiple tumorigenic processes, including proliferation, invasion, metastasis and prognosis. Using miRNA expression profiling analysis, we found that miR-630 was markedly down-regulated in three ESCC tissue samples compared with that in paired normal esophageal tissues. Differential miR-630 expression was subsequently confirmed using quantitative real-time PCR. To determine whether miR-630 down-regulation could be considered as a diagnostic indicator and adverse prognostic factor, we investigated the association between miR-630 and clinicopathological characteristics in patients with ESCC. It was found that decreased miR-630 expression was associated with poor overall survival in these patients. In addition, we also explored the biological function of miR-630 by targeting Slug and investigated the correlation between miR-630 expression and epithelial-mesenchymal transition (EMT) progression in vivo and in vitro Ectopic miR-630 expression could inhibit proliferation, invasion and metastasis, whereas miR-630 knockdown induced proliferation, invasion, metastasis and EMT traits. Overall, our study supports a role for miR-630 as a critical novel modulator in ESCC.