MiR-29a Regulates Radiosensitivity in Human Intestinal Cells by Targeting PTEN Gene

Integrated whole transcriptome profiling revealed a convoluted circular RNA-based competing endogenous RNAs regulatory network in colorectal cancer

Recently, it has been identified that circRNAs can act as miRNA sponge to regulate gene expression in various types of cancers, associating them with cancer initiation and progression. The present study aims to identify colorectal cancer-related circRNAs and the underpinning mechanisms of circRNA/miRNA/mRNA networks in the development and progress of Colorectal Cancer. Differentially expressed circRNAs, miRNAs, and mRNAs were identified in GEO microarray datasets using the Limma package of R. The analysis of differentially expressed circRNAs resulted in 23 upregulated and 31 downregulated circRNAs. CeRNAs networks were constructed by intersecting the results of predicted and experimentally validated databases, circbank and miRWalk, and by performing DEMs and DEGs analysis using Cytoscape. Next, functional enrichment analysis was performed for DEGs included in ceRNA networks. Followed by survival analysis, expression profile assessment using TCGA and GEO data, and ROC curve analysis we identified a ceRNA sub-networks that revealed the potential regulatory effect of hsa_circ_0001955 and hsa_circ_0071681 on survival-related genes, namely KLF4, MYC, CCNA2, RACGAP1, and CD44. Overall, we constructed a convoluted regulatory network and outlined its likely mechanisms of action in CRC, which may contribute to the development of more effective approaches for early diagnosis, prognosis, and treatment of CRC.

Moving the Needle Forward in Genomically-Guided Precision Radiation Treatment

Radiation treatment (RT) is a mainstay treatment for many types of cancer. Recommendations for RT and the radiation plan are individualized to each patient, taking into consideration the patient's tumor pathology, staging, anatomy, and other clinical characteristics. Information on germline mutations and somatic tumor mutations is at present rarely used to guide specific clinical decisions in RT. Many genes, such as ATM, and BRCA1/2, have been identified in the laboratory to confer radiation sensitivity. However, our understanding of the clinical significance of mutations in these genes remains limited and, as individual mutations in such genes can be rare, their impact on tumor response and toxicity remains unclear. Current guidelines, including those from the National Comprehensive Cancer Network (NCCN), provide limited guidance on how genetic results should be integrated into RT recommendations. With an increasing understanding of the molecular underpinning of radiation response, genomically-guided RT can inform decisions surrounding RT dose, volume, concurrent therapies, and even omission to further improve oncologic outcomes and reduce risks of toxicities. Here, we review existing evidence from laboratory, pre-clinical, and clinical studies with regard to how genetic alterations may affect radiosensitivity. We also summarize recent data from clinical trials and explore potential future directions to utilize genetic data to support clinical decision-making in developing a pathway toward personalized RT.

Non-coding RNAs in radiotherapy resistance: Roles and therapeutic implications in gastrointestinal cancer

Radiotherapy has become an indispensable and conventional means for patients with advanced solid tumors including gastrointestinal cancer. However, innate or acquired radiotherapy resistance remains a significant challenge and greatly limits the therapeutic effect, which results in cancer relapse and poor prognosis. Therefore, it is an urgent need to identify novel biomarkers and therapeutic targets for clarify the biological characteristics and mechanism of radiotherapy resistance. Recently, lots of studies have revealed that non-coding RNAs (ncRNAs) are the potential indicators and regulators of radiotherapy resistance via the mediation of various targets/pathways in different cancers. These findings may serve as a potential therapeutic strategy to overcome radiotherapy resistance. In this review, we will shed light on the recent findings regarding the functions and regulatory mechanisms of ncRNAs following radiotherapy, and comprehensively discuss their potential as biomarkers and therapeutic targets in radiotherapy resistance of gastrointestinal cancer.

MiR-29a-3p: a potential biomarker and therapeutic target in colorectal cancer

Cancer is frequently caused by microRNAs, which control post-transcriptional levels of gene expression by binding to target mRNAs. MiR-29a-3p has recently been shown to play a twofold function in the majority of malignancies, including colorectal cancer (CRC), according to mounting evidence. Here, we not only briefly summarize such connection between miR-29a-3p and cancers, but aslo primarily evaluate the miR-29a-3p expression pattern, clinical applicability, and molecular mechanisms in CRC to provide a guide for future studies. This review established the diagnostic and prognostic value of miR-29a-3p abnormalty in a variety of clinical samples for CRC. Furthermore, current molecular mechanisms of miR-29a-3p for regulating cancerous biological processes such growth, invasion, metastasis, the epithelial-mesenchymal transformation process, and immunomodulation through its upstream regulatory factors and downstream targeted genes were briefly explored. More specifically, miR-29a-3p has been linked to a few medications that have been shown to have anticancer benefits. To sum up, miR-29a-3p is a promising biomarker and prospective therapeutic target for the diagnosis and prognosis of CRC, but further research is still needed to establish a theoretical basis for more practical applications.

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.

LncRNA EGOT/miR-211-5p Affected Radiosensitivity of Rectal Cancer by Competitively Regulating ErbB4

BACKGROUND/AIMS

Long non-coding ribonucleic acids (lncRNAs) are involved in the progression of cancers and affect the response to radiation therapy. This study was to investigate the mechanism of lncRNA EGOT in the radiosensitivity of rectal cancer.

METHODS

The mRNA expression of EGOT, miR-211-5p and ErbB4 in rectal cancer tissues and cells was detected by qRT-PCR. The protein expression of ErbB4 was detected by Western blot. Dual-luciferase reporter assay and ribonucleic acid immunoprecipitation (RIP) were used to confirm the interaction between EGOT and miR-211-5p or miR-211-5p and ErbB4. Transfection technology was used to down-regulate and up-regulate the expression of EGOT and miR-211-5p in rectal cancer cells, respectively. MTT, colony formation and flow cytometry were used to detect the effect of EGOT and miR-211-5p on proliferation, invasion, migration and apoptosis of rectal cancer cells.

RESULTS

The expression of EGOT was up-regulated in rectal cancer tissues and cells, and the expression of EGOT was related to the late stage of pathology. EGOT knockdown inhibited the proliferation and colony formation of rectal cancer cells and induced the apoptosis of rectal cancer cells. Moreover, EGOT knockdown was significantly enhanced the effects of radiotherapy on rectal cancer in vivo and in vitro. Furthermore, EGOT was found to serve as a sponge of miR-211-5p, and ErbB4 was a downstream target of miR-211-5p. EGOT enhanced the expression of ErbB4 by regulating miR-211-5p. MiR-211-5p inhibitor restored the effect of EGOT knockdown on the radiosensitivity of rectal cancer.

CONCLUSION

Down-regulation of EGOT could inhibit the growth of rectal cancer cells by regulating the miR-211-5p/ErbB4 axis and improve the radiosensitivity of rectal cancer cells. EGOT may be a new therapeutic target for rectal cancer.

PTEN inhibitor bpV(HOpic) confers protection against ionizing radiation

Exposure to Ionizing radiation (IR) poses a severe threat to human health. Therefore, there is an urgent need to develop potent and safe radioprotective agents for radio-nuclear emergencies. Phosphatidylinositol-3-kinase (PI3K) mediates its cytoprotective signaling against IR by phosphorylating membrane phospholipids to phosphatidylinositol 3,4,5 triphosphate, PIP3, that serve as a docking site for AKT. Phosphatase and Tensin Homolog on chromosome 10 (PTEN) antagonizes PI3K activity by dephosphorylating PIP3, thus suppressing PI3K/AKT signaling that could prevent IR induced cytotoxicity. The current study was undertaken to investigate the radioprotective potential of PTEN inhibitor (PTENi), bpV(HOpic). The cell cytotoxicity, proliferation index, and clonogenic survival assays were performed for assessing the radioprotective potential of bpV(HOpic). A safe dose of bpV(HOpic) was shown to be radioprotective in three radiosensitive tissue origin cells. Further, bpV(HOpic) significantly reduced the IR-induced apoptosis and associated pro-death signaling. A faster and better DNA repair kinetics was also observed in bpV(HOpic) pretreated cells exposed to IR. Additionally, bpV(HOpic) decreased the IR-induced oxidative stress and significantly enhanced the antioxidant defense mechanism in cells. The radioprotective effect of bpV(HOpic) was found to be AKT dependant and primarily regulated by the enhanced glycolysis and associated signaling. Furthermore, this in-vitro observation was verified in-vivo, where administration of bpV(HOpic) in C57BL/6 mice resulted in AKT activation and conferred survival advantage against IR-induced mortality. These results imply that bpV(HOpic) ameliorates IR-induced oxidative stress and cell death by inducing AKT signaling mediated antioxidant defense system and DNA repair pathways, thus strengthening its potential to be used as a radiation countermeasure.

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

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

MicroRNAs for Diagnosis and Treatment of Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer worldwide, with high morbidity and mortality rates. The diagnosis and treatment of CRC have the most significant value for disease- free survival. Early diagnosis and early surgical resection are generally considered to be the most effective ways to reduce CRC mortality. In the past few years, many researchers have focused on the role of microRNAs in different tumors, making the functions of microRNAs gradually clear. The present study reviews the role of microRNAs in the diagnosis and treatment of colorectal cancer. Compared with the usual diagnosis methods and biomarker, circulating microRNAs can be promising new effective biomarkers for CRC diagnosis and treatment.

CDK6 inhibition targeted by miR-378a-3p protects against intestinal injury induced by ionizing radiation

Radiotherapy combined with chemotherapy is a common modality in abdominal cancer treatment. However, intestinal syndrome induced by radiation is a main factor leading to the poor prognosis of radiotherapy. In this work, we found that miR-378a-3p was markedly up-regulated in the small intestines of mice after total abdominal irradiation. Knocking-down (or overexpression) of miR-378a-3p increased (or decreased) the radiosensitivity of the small intestine cells HIEC and FHs-74-Int. Comet assay and γ-H2AX staining demonstrated that miR-378a-3p exerted its radioprotective function by reducing the accumulation of DNA damage in the cells and tissues of the small intestines. Mechanistically, miR-378a-3p could interact with the 3' UTR of CDK6 through complementary sequences and thus inhibited CDK6 expression in the small intestine cells. Rescue experiments suggested that the repression of miR-378a-3p overexpression on cell radiosensitivity and DNA damage accumulation was abrogated by the forced expression of CDK6. In summary, our results revealed for the first time that miR-378a-3p regulated the radiosensitivity and DNA damage response of small intestines by targeting CDK6. MiR-378a-3p may serve as a promising biomarker and radioprotective target in abdominal cancer.

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.

Long non‑coding RNA GAS5 increases the radiosensitivity of A549 cells through interaction with the miR‑21/PTEN/Akt axis

Radioresistance hinders the therapeutic outcomes of radiotherapy in non-small cell lung cancer (NSCLC). Although long non-coding RNAs (lncRNAs) have been demonstrated to participate in the regulation of multiple cell behaviors, whether they can modulate the radiosensitivity of NSCLC and the underlying molecular mechanisms have not been well investigated. In the present study, it was revealed that NSCLC NCI-H460 cells were more sensitive to ionizing radiation (IR) than A549 cells. Using the RNA-Seq method, four highly differentially expressed lncRNAs were identified, including the growth arrest-specific transcript 5 (GAS5), syntaxin binding protein 5 antisense RNA 1 (STXBP5-AS1), metastasis associated lung adenocarcinoma transcript 1 (MALAT1) and X-inactive specific transcript (XIST), which were predicted to play roles in the acquisition of radiosensitivity. Using real-time quantitative PCR (qPCR), it was demonstrated that lncRNA GAS5 was significantly upregulated in NCI-H460 cells but not in A549 cells during IR. Mechanistically, it was demonstrated that overexpression of lncRNA GAS5 decreased the level of microRNA-21 (miR-21). Overexpression of lncRNA GAS5 or suppression of miR-21 markedly increased the IR-induced cell apoptosis of A549 cells. It was also demonstrated that overexpression of lncRNA GAS5 increased PTEN expression and suppressed Akt phosphorylation through the modulation of miR-21. Notably, it was revealed that IR enhanced the interaction between lncRNA GAS5 and the miR-21/PTEN/Akt axis. In summary, the present findings revealed that lncRNA GAS5 has a radiosensitization effect on NSCLC, indicating the potential application of lncRNA GAS5 in NSCLC radiotherapy.

MiR-20b Down-Regulates Intestinal Ferroportin Expression In Vitro and In Vivo

Ferroportin (FPN) is the only known cellular iron exporter in mammalian. However, post-transcriptional regulation of intestinal FPN has not yet been completely understood. In this study, bioinformatics algorithms (TargetScan, PicTar, PITA, and miRanda) were applied to predict, screen and obtain microRNA-17 family members (miR-17, miR-20a, miR-20b, and miR-106a) targeting FPN, ‘seed sequence’ and responding binding sites on the 3′untranslated region (3′UTR) region of FPN. Dual-luciferase reporter assays revealed miRNA-17 family members’ mimics decreased the luciferase activity, whereas their inhibitors increased the luciferase activity. Compared with the FPN 3′UTR wild type reporter, co-transfection of a miRNA-17 family members’ over-expression plasmids and FPN 3′UTR mutant reporters enhanced the luciferase activity in HCT116 cells. Transfection with miR-20b overexpression plasmid significantly enhanced its expression, and it inhibited endogenous FPN protein expression in Caco-2 cells. Additionally, tail-vein injection of miR-20b resulted in increasing duodenal miR-20b expression, decreasing duodenal FPN protein expression, which was closely related to lower plasma iron level in mice. Taken together, these data suggest that the miR-20b is identified to regulate intestinal FPN expression in vitro and in vivo, which will provide a potential target for intestinal iron exportation.

Identification and Functional Verification of MicroRNA-16 Family Targeting Intestinal Divalent Metal Transporter 1 (DMT1) in vitro and in vivo

Divalent metal transporter 1 (DMT1) is a key transporter of iron uptake and delivering in human and animals. However, post-transcriptional regulation of DMT1 is poorly understood. In this study, bioinformatic algorithms (TargetScan, PITA, miRanda, and miRDB) were applied to predict, screen, analyze, and obtain microRNA-16 family members (miR-16, miR-195, miR-497, and miR-15b) targeting DMT1, seed sequence and their binding sites within DMT1 3′ untranslated region (3′ UTR) region. As demonstrated by dual-luciferase reporter assays, luciferase activity of DMT1 3′ UTR reporter was impaired/enhanced when microRNA-16 family member over-expression plasmid/its inhibitor was transfected to HCT116 cells. Corroboratively, co-transfection of microRNA-16 family member over-expression plasmid and DMT1 3′ UTR mutant reporter repressed the luciferase activity in HCT116 cells. In addition, over-expression microRNA-16 family member augmented its expression and diminished DMT1 protein expression in HCT116 cells. Interestingly, tail vein injection of miR-16 assay revealed reduced plasma iron levels, higher miR-16 expression, and lower DMT1 protein expression in the duodenum of mice. Taken together, we provide evidence that microRNA-16 family (miR-16, miR-195, miR-497, and miR-15b) is confirmed to repress intestinal DMT1 expression in vitro and in vivo, which will give valuable insight into post-transcriptional regulation of DMT1.

Improved Radiotherapy Sensitivity of Nasopharyngeal Carcinoma Cells by miR-29-3p Targeting COL1A1 3'-UTR

Background

Radio-resistance is an obstacle to the treatment of human nasopharyngeal carcinoma (NPC). However, how microRNAs (miRNA) are involved in this process remains unclear. In the present study we explored the role and possible molecular mechanism of miR-29a-3p, formerly known as tumor suppressors, in radio-sensitivity of NPC cells.

Material/Methods

A radio-resistant sub-cell line, CNE-2R, was established to detect the expression of miR-29a/b/c-3p using qRT-PCR. CCK-8 assay, colony formation assay, and single-cell gel electrophoresis (SCGE) assay were carried out to analyze the radio-sensitivity of NPC cells. qRT-PCR, luciferase reporter, and Western blot experiments were performed to validate the targeting of COL1A1 by miR-29a. Short interference RNAs (siRNAs) were used to investigate whether COL1A1 mediates the radio-sensitizer role of miR-29a. Expression of miR-29a and COL1A1 in radio-resistant NPC tissues was finally determined.

Results

miR-29a was decreased in the radio-resistant CNE-2R cells. Following a time-course irradiation (IR) exposure, miR-29a exhibited a time-dependent decrease. Cellular experiments confirmed that miR-29a induced radio-sensitivity of CNE-2R cells via suppressing cell viability and enhancing cell apoptosis after IR. We confirmed that COL1A1 is a direct target of miR-29a and can exert radio-resistance effects in NPC cells. We also found that knockdown of COL1A1 inhibits NPC cell viability and sensitivity to IR. Finally, we observed a downregulation of miR-29a in radio-resistant NPC tissues and its decrease was associated with upregulation of COL1A1.

Conclusions

miR-29a is a critical determinant of NPC radio-response for NPC patients, and its induction provides a promising therapeutic choice to elevate NPC radio-sensitivity.

A review of radiation genomics: integrating patient radiation response with genomics for personalised and targeted radiation therapy

Background

The success of radiation therapy for cancer patients is dependent on the ability to deliver a total tumouricidal radiation dose capable of eradicating all cancer cells within the clinical target volume, however, the radiation dose tolerance of the surrounding healthy tissues becomes the main dose-limiting factor. The normal tissue adverse effects following radiotherapy are common and significantly impact the quality of life of patients. The likelihood of developing these adverse effects following radiotherapy cannot be predicted based only on the radiation treatment parameters. However, there is evidence to suggest that some common genetic variants are associated with radiotherapy response and the risk of developing adverse effects. Radiation genomics is a field that has evolved in recent years investigating the association between patient genomic data and the response to radiation therapy. This field aims to identify genetic markers that are linked to individual radiosensitivity with the potential to predict the risk of developing adverse effects due to radiotherapy using patient genomic information. It also aims to determine the relative radioresponse of patients using their genetic information for the potential prediction of patient radiation treatment response.

Methods and materials

This paper reports on a review of recent studies in the field of radiation genomics investigating the association between genomic data and patients response to radiation therapy, including the investigation of the role of genetic variants on an individual’s predisposition to enhanced radiotherapy radiosensitivity or radioresponse.

Conclusion

The potential for early prediction of treatment response and patient outcome is critical in cancer patients to make decisions regarding continuation, escalation, discontinuation, and/or change in treatment options to maximise patient survival while minimising adverse effects and maintaining patients’ quality of life.

Inhibition of miR-23a increases the sensitivity of lung cancer stem cells to erlotinib through PTEN/PI3K/Akt pathway

Epidermal growth factor receptor-targeted tyrosine kinase inhibitors (EGFR-TKIs) have become first-line drugs used for non-small cell lung cancer (NSCLC) treatment. However, drug resistance to EGFR-TKIs will be developed inevitably due to the repeated use of these drugs. In the present study, we isolated cancer stem cells (CSCs) from the PC9 NSCLC cell line. We then observed that the PC9 CSCs showed significant resistance to erlotinib compared with the PC9 non-CSCs. Erlotinib failed to suppress the phosphorylation of PI3K and AKT in PC9 CSCs, although the EGFR was inhibited sufficiently. Mechanically, we observed aberrant upregulation of microRNA-23a (miR-23a) and downregulation of PTEN in PC9 CSCs compared to PC9 non-CSCs. Luciferase reporter assays proved that PTEN was the target of miR-23a in PC9 CSCs. Furthermore, knockdown of miR-23a enhanced the antitumor effect of erlotinib by increasing the expression of PTEN. In addition, transfection with miR-23a inhibitors promoted the erlotinib-dependent inhibition of PI3K/AKT pathway, thus, suppressing the proliferation and inducing apoptosis in PC9 CSCs. These results propose that upregulation of miR-23a is a potential mechanism associated with resistance to EGFR-TKIs in lung cancer stem cells. Inhibition of miR-23a serves as a novel therapeutic strategy to eliminate the EGFR-TKIs resistance of lung cancer stem cells.