miR-205 enhances radiation sensitivity of prostate cancer cells by impairing DNA damage repair through PKCε and ZEB1 inhibition

Molecular panorama of therapy resistance in prostate cancer: a pre-clinical and bioinformatics analysis for clinical translation

Prostate cancer (PCa) is a malignant disorder of prostate gland being asymptomatic in early stages and high metastatic potential in advanced stages. The chemotherapy and surgical resection have provided favourable prognosis of PCa patients, but advanced and aggressive forms of PCa including CRPC and AVPC lack response to therapy properly, and therefore, prognosis of patients is deteriorated. At the advanced stages, PCa cells do not respond to chemotherapy and radiotherapy in a satisfactory level, and therefore, therapy resistance is emerged. Molecular profile analysis of PCa cells reveals the apoptosis suppression, pro-survival autophagy induction, and EMT induction as factors in escalating malignant of cancer cells and development of therapy resistance. The dysregulation in molecular profile of PCa including upregulation of STAT3 and PI3K/Akt, downregulation of STAT3, and aberrant expression of non-coding RNAs are determining factor for response of cancer cells to chemotherapy. Because of prevalence of drug resistance in PCa, combination therapy including co-utilization of anti-cancer drugs and nanotherapeutic approaches has been suggested in PCa therapy. As a result of increase in DNA damage repair, PCa cells induce radioresistance and RelB overexpression prevents irradiation-mediated cell death. Similar to chemotherapy, nanomaterials are promising for promoting radiosensitivity through delivery of cargo, improving accumulation in PCa cells, and targeting survival-related pathways. In respect to emergence of immunotherapy as a new tool in PCa suppression, tumour cells are able to increase PD-L1 expression and inactivate NK cells in mediating immune evasion. The bioinformatics analysis for evaluation of drug resistance-related genes has been performed.

PrLZ regulates EMT and invasion in prostate cancer via the TGF-β1/p-smad2/miR-200 family/ZEB1 axis

BACKGROUND

Prostate leucine zipper (PrLZ) is a prostate-specific protein, and our previous study demonstrated that PrLZ enhances the malignant progression of prostate cancer (Pca). However, the roles of PrLZ in epithelial to mesenchymal transition (EMT) remain unknown.

METHODS

Quantitative real-time PCR (qRT-PCR), immunohistochemical (IHC) staining, hematoxylin-eosin (HE) staining, and western blotting were used to analyze the expression of protein and genes level in human PCa cell lines. Invasion assay was used to examine the effect of PrLZ, miR-200a, miR-200b, miR-200c, miR-141, miR-429, miR-205, and ZEB1 on PCa cell line invasion in vitro. Prostate cancer metastasis animal model was designed to assess the effect of PrLZ on PCa cell line invasion in vivo.

RESULTS

We proved that high PrLZ expression initiates EMT, which was shown by the downregulation of E-cadherin and upregulation of vimentin in PC-3/PrLZ and ARCaP-E/PrLZ cells. Mechanistic analysis revealed that PrLZ regulates EMT by activating TGF-β1/p-smad2 signaling and further inhibiting the expression of miR-200 family members, which negatively regulates ZEB1 expression and causes EMT in Pca. Moreover, using two of orthotopic mouse model and tail vein injection of human prostate cancer cells mouse model, we observed that PC-3/PrLZ cells led to the development of distant organ metastases in vivo.

CONCLUSIONS

Our results show the mechanism by which PrLZ regulates EMT and metastasis and suggest that PrLZ may be a potential therapeutic target for Pca metastasis.

Radiotherapy Metastatic Prostate Cancer Cell Lines Treated with Gold Nanorods Modulate miRNA Signatures

MicroRNA (miRNA) modulation has been identified as a promising strategy for improving the response of human prostate cancer (PCa) to radiotherapy (RT). Studies have shown that mimics or inhibitors of miRNAs could modulate the sensitivity of PCa cells to RT. In addition, pegylated gold nanoparticles have been studied as a therapeutic approach to treat PCa cells and/or vehicles for carrying miRNAs to the inside of cells. Therefore, we evaluated the capacity of hypofractionated RT and pegylated gold nanorods (AuNPr-PEG) to modulate the miRNA signature on PCa cells. Thus, RT-qPCR was used to analyze miRNA-95, miRNA-106-5p, miRNA-145-5p, and miRNA-541-3p on three human metastatic prostate cell lines (PC3, DU145, and LNCaP) and one human prostate epithelial cell line (HprEpiC, a non-tumor cell line) with and without treatment. Our results showed that miRNA expression levels depend on cell type and the treatment combination applied using RT and AuNPr-PEG. In addition, cells pre-treated with AuNPr-PEG and submitted to 2.5 Gy per day for 3 days decreased the expression levels of miRNA-95, miRNA-106, miRNA-145, and miRNA-541-3p. In conclusion, PCa patients submitted to hypofractionated RT could receive personalized treatment based on their metastatic cellular miRNA signature, and AuNPr-PEG could be used to increase metastatic cell radiosensitivity.

The crosstalk between miRNAs and signaling pathways in human cancers: Potential therapeutic implications

MicroRNAs (miRNAs) are increasingly recognized as central players in the regulation of eukaryotic physiological processes. These small double stranded RNA molecules have emerged as pivotal regulators in the intricate network of cellular signaling pathways, playing significant roles in the development and progression of human cancers. The central theme in miRNA-mediated regulation of signaling pathways involves their ability to target and modulate the expression of pathway components. Aberrant expression of miRNAs can either promote or suppress key signaling events, influencing critical cellular processes such as proliferation, apoptosis, angiogenesis, and metastasis. For example, oncogenic miRNAs often promote cancer progression by targeting tumor suppressors or negative regulators of signaling pathways, thereby enhancing pathway activity. Conversely, tumor-suppressive miRNAs frequently inhibit oncogenic signaling by targeting key components within these pathways. This complex regulatory crosstalk underscores the significance of miRNAs as central players in shaping the signaling landscape of cancer cells. Furthermore, the therapeutic implications of targeting miRNAs in cancer are substantial. miRNAs can be manipulated to restore normal signaling pathway activity, offering a potential avenue for precision medicine. The development of miRNA-based therapeutics, including synthetic miRNA mimics and miRNA inhibitors, has shown promise in preclinical and clinical studies. These strategies aim to either enhance the activity of tumor-suppressive miRNAs or inhibit the function of oncogenic miRNAs, thereby restoring balanced signaling and impeding cancer progression. In conclusion, the crosstalk between miRNAs and signaling pathways in human cancers is a dynamic and influential aspect of cancer biology. Understanding this interplay provides valuable insights into cancer development and progression. Harnessing the therapeutic potential of miRNAs as regulators of signaling pathways opens up exciting opportunities for the development of innovative cancer treatments with the potential to improve patient outcomes. In this chapter, we provide an overview of the crosstalk between miRNAs and signaling pathways in the context of cancer and highlight the potential therapeutic implications of targeting this regulatory interplay.

Spatial and Temporal Relationship between Epithelial-Mesenchymal Transition (EMT) and Stem Cells in Cancer

BACKGROUND

Epithelial-mesenchymal transition (EMT) is often linked with carcinogenesis. However, EMT is also important for embryo development and only reactivates in cancer. Connecting how EMT occurs during embryonic development and in cancer could help us further understand the root mechanisms of cancer diseases.

CONTENT

There are key regulatory elements that contribute to EMT and the induction and maintenance of stem cell properties during embryogenesis, tissue regeneration, and carcinogenesis. Here, we explore the implications of EMT in the different stages of embryogenesis and tissue development. We especially highlight the necessity of EMT in the mesodermal formation and in neural crest cells. Through EMT, these cells gain epithelial-mesenchymal plasticity (EMP). With this transition, crucial morphological changes occur to progress through the metastatic cascade as well as tissue regeneration after an injury. Stem-like cells, including cancer stem cells, are generated from EMT and during this process upregulate factors necessary for stem cell maintenance. Hence, it is important to understand the key regulators allowing stem cell awakening in cancer, which increases plasticity and promotes treatment resistance, to develop strategies targeting this cell population and improve patient outcomes.

SUMMARY

EMT involves multifaceted regulation to allow the fluidity needed to facilitate adaptation. This regulatory mechanism, plasticity, involves many cooperating transcription factors. Additionally, posttranslational modifications, such as splicing, activate the correct isoforms for either epithelial or mesenchymal specificity. Moreover, epigenetic regulation also occurs, such as acetylation and methylation. Downstream signaling ultimately results in the EMT which promotes tissue generation/regeneration and cancer progression.

Unleashing the pathological imprinting of cancer in autoimmunity: Is ZEB1 the answer?

The intriguing scientific relationship between autoimmunity and cancer immunology have been traditionally indulged to throw spotlight on novel pathological targets. Understandably, these "slowly killing" diseases are on the opposite ends of the immune spectrum. However, the immune regulatory mechanisms between autoimmunity and cancer are not always contradictory and sometimes mirror each other based on disease stage, location, and timepoint. Moreover, the blockade of immune checkpoint molecules or signalling pathways that unleashes the immune response against cancer is being leveraged to preserve self-tolerance and treat many autoimmune disorders. Therefore, understanding the common crucial factors involved in cancer is of paramount importance to paint the autoimmune disease spectrum and validate novel drug candidates. In the current review, we will broadly describe how ZEB1, or Zinc-finger E-box Binding Homeobox 1, reinforces immune exhaustion in cancer or contributes to loss of self-tolerance in auto-immune conditions. We made an effort to exchange information about the molecular pathways and pathological responses (immune regulation, cell proliferation, senescence, autophagy, hypoxia, and circadian rhythm) that can be regulated by ZEB1 in the context of autoimmunity. This will help untwine the intricate and closely postured pathogenesis of ZEB1, that is less explored from the perspective of autoimmunity than its counterpart, cancer. This review will further consider several approaches for targeting ZEB1 in autoimmunity.

MicroRNAs as biomarkers for early diagnosis, targeting and prognosis of prostate cancer

Globally, prostate cancer (PC) is leading cause of cancer-related mortality in men worldwide. Despite significant advances in the treatment and management of this disease, the cure rates for PC remains low, largely due to late detection. PC detection is mostly reliant on prostate-specific antigen (PSA) and digital rectal examination (DRE); however, due to the low positive predictive value of current diagnostics, there is an urgent need to identify new accurate biomarkers. Recent studies support the biological role of microRNAs (miRNAs) in the initiation and progression of PC, as well as their potential as novel biomarkers for patients' diagnosis, prognosis, and disease relapse. In the advanced stages, cancer-cell-derived small extracellular vesicles (SEVs) may constitute a significant part of circulating vesicles and cause detectable changes in the plasma vesicular miRNA profile. Recent computational model for the identification of miRNA biomarkers discussed. In addition, accumulating evidence indicates that miRNAs can be utilized to target PC cells. In this article, the current understanding of the role of microRNAs and exosomes in the pathogenesis and their significance in PC prognosis, early diagnosis, chemoresistance, and treatment are reviewed.

Application of nano-radiosensitizers in combination cancer therapy

Radiosensitizers are compounds or nanostructures, which can improve the efficiency of ionizing radiation to kill cells. Radiosensitization increases the susceptibility of cancer cells to radiation-induced killing, while simultaneously reducing the potentially damaging effect on the cellular structure and function of the surrounding healthy tissues. Therefore, radiosensitizers are therapeutic agents used to boost the effectiveness of radiation treatment. The complexity and heterogeneity of cancer, and the multifactorial nature of its pathophysiology has led to many approaches to treatment. The effectiveness of each approach has been proven to some extent, but no definitive treatment to eradicate cancer has been discovered. The current review discusses a broad range of nano-radiosensitizers, summarizing possible combinations of radiosensitizing NPs with several other types of cancer therapy options, focusing on the benefits and drawbacks, challenges, and future prospects.

RNAi-Based Therapeutics and Novel RNA Bioengineering Technologies

RNA interference (RNAi) provides researchers with a versatile means to modulate target gene expression. The major forms of RNAi molecules, genome-derived microRNAs (miRNAs) and exogenous small interfering RNAs (siRNAs), converge into RNA-induced silencing complexes to achieve posttranscriptional gene regulation. RNAi has proven to be an adaptable and powerful therapeutic strategy where advancements in chemistry and pharmaceutics continue to bring RNAi-based drugs into the clinic. With four siRNA medications already approved by the US Food and Drug Administration (FDA), several RNAi-based therapeutics continue to advance to clinical trials with functions that closely resemble their endogenous counterparts. Although intended to enhance stability and improve efficacy, chemical modifications may increase risk of off-target effects by altering RNA structure, folding, and biologic activity away from their natural equivalents. Novel technologies in development today seek to use intact cells to yield true biologic RNAi agents that better represent the structures, stabilities, activities, and safety profiles of natural RNA molecules. In this review, we provide an examination of the mechanisms of action of endogenous miRNAs and exogenous siRNAs, the physiologic and pharmacokinetic barriers to therapeutic RNA delivery, and a summary of the chemical modifications and delivery platforms in use. We overview the pharmacology of the four FDA-approved siRNA medications (patisiran, givosiran, lumasiran, and inclisiran) as well as five siRNAs and several miRNA-based therapeutics currently in clinical trials. Furthermore, we discuss the direct expression and stable carrier-based, in vivo production of novel biologic RNAi agents for research and development. SIGNIFICANCE STATEMENT: In our review, we summarize the major concepts of RNA interference (RNAi), molecular mechanisms, and current state and challenges of RNAi drug development. We focus our discussion on the pharmacology of US Food and Drug Administration-approved RNAi medications and those siRNAs and miRNA-based therapeutics that entered the clinical investigations. Novel approaches to producing new true biological RNAi molecules for research and development are highlighted.

Exosomal miRNAs-a diagnostic biomarker acting as a guiding light in the diagnosis of prostate cancer

Prostate cancer, one of the major causes of mortality globally is regarded as the second leading cause of mortality among men. It is known to affect the stromal cells surrounding it. Through the use of exosomes, the affected stromal cells can promote the growth and spread of the cancer. Exosomes are known to play a role not only in the development and progression of cancer but also contribute to the drug-resistance character of cancer cells. Recently, the discovery of the small non-coding RNAs or miRNA has attracted attention of cancer researchers as they can regulate the expression of different genes. Therefore, exosomal miRNA can be used as a novel and reliable biomarker for the diagnosis and treatment of prostate cancer. In addition, exosomal miRNAs can also be used as a potential treatment for prostate cancer. The goal of this review is to provide a comprehensive analysis of the current knowledge about the role of exosomal miRNAs in the treatment of patients with prostate cancer and their potential role in monitoring the disease.

microRNA-205 in prostate cancer: Overview to clinical translation

Prostate cancer (PrCa) is the most common type of cancer among men in the United States. The metastatic and advanced PrCa develops drug resistance to current regimens which accounts for the poor management. microRNAs (miRNAs) have been well-documented for their diagnostic, prognostic, and therapeutic roles in various human cancers. Recent literature confirmed that microRNA-205 (miR-205) has been established as one of the tumor suppressors in PrCa. miR-205 regulates number of cellular functions, such as proliferation, invasion, migration/metastasis, and apoptosis. It is also evident that miR-205 can serve as a key biomarker in diagnostic, prognostic, and therapy of PrCa. Therefore, in this review, we will provide an overview of tumor suppressive role of miR-205 in PrCa. This work also outlines miR-205's specific role in targeted mechanisms for chemosensitization and radiosensitization in PrCa. A facile approach of delivery paths for successful clinical translation is documented. Together, all these studies provide a novel insight of miR-205 as an adjuvant agent for reducing the widening gaps in clinical outcome of PrCa patients.

Analysis of the miRNA expression profile of laboratory red crucian carp under low-dose caesium-137 irradiation

Radiation can cause the differential expression of biological miRNA molecules. This research was based on the development of the laboratory red crucian carp (LRCC) to explore the feasibility of its application in the detection of low-dose ionizing radiation-induced biological damage in aquatic environments and the development of related molecular markers. Adult LRCC were irradiated with caesium-137 at 0.3 Gy, while RNA-seq and bioinformatics techniques were used to identify miRNAs that were differentially expressed relative to their levels in the nonirradiation group. Analysis of liver sections showed that liver cells in the radiation group showed nuclear pyknosis. In this study, 34 miRNAs differentially expressed in the liver of LRCC after irradiation were identified, among which seven were new crucian carp miRNAs; a total of 632 target genes were predicted in the prediction analysis. The results of comprehensive GO enrichment and KEGG pathway analyses showed that these target genes were mainly involved in energy transfer and material catabolism, especially malonyl-CoA biosynthesis, acetyl-CoA carboxylase activity, fatty acid biosynthesis and metabolism, and pyruvate metabolism; in addition, the AMPK signalling pathway was the most active pathway. This study shows that the LRCC is sensitive to radiation, or can be used as a candidate experimental animal to study the biological effects of radiation, and the screened miRNA can be used as a pre-selected biomarker for radiation damage detection and radiation biological environmental monitoring. CLINICAL TRIALS REGISTRATION: None.

MiR-106b-5p Attenuates Neuropathic Pain by Regulating the P2X4 Receptor in the Spinal Cord in Mice

The P2X4 receptor (P2X4R) can be upregulated after nerve injury, and its mediated spinal microglial activation makes a critical contribution to pathologically enhanced pain processing in the dorsal horn. Although some studies have partly clarified the mechanism underlying altered P2X4R expression, the specific mechanism is not well understood. MicroRNAs (miRNAs) are small noncoding RNAs which control gene expression by binding with their target mRNAs. Thus, in the present study, we investigated whether miRNA is involved in the pathogenesis of neuropathic pain by regulating P2X4R. Our results showed that P2X4R was upregulated in the spinal dorsal horn of mice following spared nerve injury (SNI), and 69 miRNAs (46 upregulated and 23 downregulated miRNAs) were differentially expressed (fold change > 2.0, P < 0.05). P2X4R was found to be a major target of miR-106b-5p (one of the downregulated miRNAs) using bioinformatics technology; quantitative real-time PCR analysis confirmed the change in expression of miR-106b-5p, and dual-luciferase reporter assays confirmed the correlation between them. Fluorescence in situ hybridization was used to show cell co-localization of P2X4R and miR-106b-5p in the spinal dorsal horn. Transfection with miR-106b-5p mimic into BV2 cells reversed the upregulation of P2X4R induced by lipopolysaccharide (LPS). Moreover, miR-106b-5p overexpression significantly attenuated neuropathic pain induced by SNI, with decreased expression of P2X4R mRNA and protein in the spinal dorsal horn; intrathecal miR-106b-5p antagomir induced pain behaviors, and increased expression of P2X4R in the spinal dorsal horn of naïve mice. These data suggest that miR-106b-5p can serve as an important regulator of neuropathic pain development by targeting P2X4R.

Deoxyelephantopin Induces Apoptosis and Enhances Chemosensitivity of Colon Cancer via miR-205/Bcl2 Axis

Colon cancer (CC) is one of the major causes of cancer death in humans. Despite recent advances in the management of CC, the prognosis is still poor and a new strategy for effective therapy is imperative. Deoxyelephantopin (DET), extracted from an important medicinal plant, Elephantopus scaber L., has been reported to exhibit excellent anti-inflammatory and -cancer activities, while the detailed anti-cancer mechanism remains unclear. Herein, we found that DET showed a significant CC inhibiting effect in vitro and in vivo without obvious organ toxicity. Mechanistically, DET inhibited CC cells and tumor growth by inducing G2/M phase arrest and subsequent apoptosis. DET-mediated cell cycle arrest was caused by severe DNA damage, and DET decreased the Bcl2 expression level in a dose-dependent manner to promote CC cell apoptosis, whereas restoring Bcl2 expression reduced apoptosis to a certain extent. Moreover, we identified a microRNA complementary to the 3'-UTR of Bcl2, miR-205, that responded to the DET treatment. An inhibitor of miR-205 could recover Bcl2 expression and promoted the survival of CC cells upon DET treatment. To further examine the potential value of the drug, we evaluated the combinative effects of DET and 5-Fluorouracil (5FU) through Jin's formula and revealed that DET acted synergistically with 5FU, resulting in enhancing the chemotherapeutic sensitivity of CC to 5FU. Our results consolidate DET as a potent drug for the treatment of CC when it is used alone or combined with 5FU, and elucidate the importance of the miR-205-Bcl2 axis in DET treatment.

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.

Cabazitaxel suppresses the proliferation and promotes the apoptosis and radiosensitivity of castration-resistant prostate cancer cells by inhibiting PI3K/AKT pathway

BACKGROUND

Cabazitaxel has been applied to the treatment of castration-resistant prostate cancer (CRPC), but the molecular mechanism remained to be fully understood.

METHODS

After treatment with Cabazitaxel alone or in combination with ionizing radiation (IR), CRPC cell viability, proliferation and apoptosis were determined by Cell Counting Kit-8 (CCK-8) assay, colony formation, and flow cytometry, respectively. Tumor volume was measured after the establishment of animal xenograft model. Relative expressions of proteins related to apoptosis (B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), and cleaved caspase 3) and phosphoinositide 3-kinase (PI3K)/AKT pathway were measured by Western blot, and the phosphorylated-PI3K/PI3K and p-AKT/AKT ratios were determined as well.

RESULTS

Cell viability and proliferation were suppressed, and apoptosis was promoted in CRPC cells after Cabazitaxel treatment alone, accompanied with upregulated expressions of Bax and cleaved caspase 3 and downregulated Bcl-2 expression. Also, a single treatment with Cabazitaxel resulted in suppression of PI3K/AKT pathway activation, along with downregulated expressions of p-PI3K and p-AKT and a reduced ratio of p-PI3K/PI3K to p-AKT/AKT. Meanwhile, Cabazitaxel enhanced the effects of IR on suppressing survival and promoting apoptosis in CRPC cells through downregulating Bcl-2 and upregulating Bax and cleaved caspase 3. However, Cabazitaxel suppressed IR-induced PI3K/AKT pathway activation via downregulating p-PI3K and p-AKT, leading to a reduced ratio of p-PI3K/PI3K to p-AKT/AKT. Furthermore, Cabazitaxel further promoted the effects of IR on suppressing tumor growth in vivo.

CONCLUSION

Cabazitaxel inhibited the proliferation and promoted the apoptosis and radiosensitivity of CRPC cells, which is related to the suppression of PI3K/AKT pathway, providing a therapeutic method for CRPC in clinical practice.

The Role of MiRNA in Cancer: Pathogenesis, Diagnosis, and Treatment

Cancer is also determined by the alterations of oncogenes and tumor suppressor genes. These gene expressions can be regulated by microRNAs (miRNA). At this point, researchers focus on addressing two main questions: "How are oncogenes and/or tumor suppressor genes regulated by miRNAs?" and "Which other mechanisms in cancer cells are regulated by miRNAs?" In this work we focus on gathering the publications answering these questions. The expression of miRNAs is affected by amplification, deletion or mutation. These processes are controlled by oncogenes and tumor suppressor genes, which regulate different mechanisms of cancer initiation and progression including cell proliferation, cell growth, apoptosis, DNA repair, invasion, angiogenesis, metastasis, drug resistance, metabolic regulation, and immune response regulation in cancer cells. In addition, profiling of miRNA is an important step in developing a new therapeutic approach for cancer.

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.

Crucial Roles of microRNA-Mediated Autophagy in Urologic Malignancies

Urologic oncologies are major public health problems worldwide. Both microRNA and autophagy, separately or concurrently, are involved in a variety of the cellular and molecular processes of multiple cancers, including urologic malignancies. In this review, we have summarized the related studies and found that microRNA-mediated autophagy acted as carcinogenic factors or suppressors in prostate cancer, kidney cancer, and bladder cancer. MiRNAs, targeted genes, and the different signaling pathways constitute a complex network that orchestrates autophagy regulation, militating the oncogenic and tumor-suppressive effects in urologic malignancies. Aberrant expression of miRNAs may induce the dysregulation of the autophagy process, resulting in tumorigenesis, progression, and resistance to anticancer therapies. Targeting specific miRNAs for autophagy modulation may present as reliable diagnostic and prognostic biomarkers or promising therapeutic strategies for urologic oncologies.

MiR-223-3p targets FOXO3a to inhibit radiosensitivity in prostate cancer by activating glycolysis

AIMS

The incidence and detection rate of prostate cancer in China have been increasing in recent years. Radiotherapy is the ideal treatment for non-metastatic prostate cancer (PCa), but the effectiveness of radiotherapy is greatly discounted due to radio resistance. Therefore, relieving the radiotherapy resistance of PCa is key to improve the clinical efficacy of PCA.

MAIN METHODS

Cell proliferation was estimated using the MTT and clone formation assays. Cell apoptosis was estimated using the Annexin V-FITC/propidium iodide (PI) staining assay. Glucose uptake and lactose and ATP production were used to detect glycolysis.

KEY FINDINGS

miR-223-3p was significantly upregulated in clinically collected urine samples and PCa cells with low radiosensitivity. Enhancing miR-223-3p reduced radiosensitivity further, while inhibiting miR-223-3p improved the radiosensitivity of PC3 and LNCaP cells. Importantly, miR-223-3p regulated radiosensitivity by enhancing cell glycolysis. FOXO3a was a key target of miRNA-223-3p regulating glycolysis and radiosensitivity. Overexpression of FOXO3a abated the glycolysis level and alleviated the radioresistance caused by enhancing miR-223-3p to a certain extent.

SIGNIFICANCE

This is novel research on the role of miR-223-3p in promoting radiotherapy resistance of PCa cells by activating glycolysis. This approach provides a new perspective and ideas for alleviating radiotherapy resistance of PCa cells.

RBM5-AS1 promotes radioresistance in medulloblastoma through stabilization of SIRT6 protein

Cancer stem cells (CSCs) contribute to radioresistance in medulloblastoma. Thus, identification of key regulators of medulloblastoma stemness is critical for improving radiotherapy for medulloblastoma. In the present study, we profiled CSC-related long non-coding RNAs (lncRNAs) between radioresistant and parental medulloblastoma cells. The roles of the lncRNA RBM5-AS1 in the stemness and radiosensitivity of medulloblastoma cells were investigated. We found that RBM5-AS1, a novel inducer of medulloblastoma stemness, was significantly upregulated in radioresistant medulloblastoma cells compared to parental cells. Knockdown of RBM5-AS1 diminished the viability and clonogenic survival of both radioresistant and parental medulloblastoma cells after radiation. Silencing of RBM5-AS1 significantly enhanced radiation-induced apoptosis and DNA damage. In vivo studies confirmed that depletion of RBM5-AS1 inhibited tumor growth and increased radiosensitivity in a medulloblastoma xenograft model. In contrast, overexpression of RBM5-AS1 reduced radiation-induced apoptosis and DNA damage in medulloblastoma cells. Mechanistically, RBM5-AS1 interacted with and stabilized sirtuin 6 (SIRT6) protein. Silencing of SIRT6 reduced the stemness and reinforced radiation-induced DNA damage in medulloblastoma cells. Overexpression of SIRT6 rescued medulloblastoma cells from RBM5-AS1 depletion-induced radiosensitization and DNA damage. Overall, we identify RBM5-AS1 as an inducer of stemness and radioresistance in medulloblastoma. Targeting RBM5-AS1 may represent a potential strategy to overcome the resistance to radiotherapy in this malignancy.

Role of ZEB family members in proliferation, metastasis and chemoresistance of prostate cancer cells: Revealing signaling networks

Prostate cancer (PCa) is one of the leading causes of death worldwide. A variety of strategies including surgery, chemotherapy, radiotherapy and immunotherapy are applied for PCa treatment. PCa cells are responsive towards therapy at early stages, but they can obtain resistance in the advanced stage. Furthermore, their migratory ability is high in advanced stages. It seems that genetic and epigenetic factors play an important in this case. Zinc finger E-box-binding homeobox (ZEB) is a family of transcription with two key members including ZEB1 and ZEB2. ZEB family members are known due to their involvement in promoting cancer metastasis via EMT induction. Recent studies have shown their role in cancer proliferation and inducing therapy resistance. In the current review, we focus on revealing role of ZEB1 and ZEB2 in PCa. ZEB family members that are able to significantly promote proliferation and viability of cancer cells. ZEB1 and ZEB2 enhance migration and invasion of PCa cells via EMT induction. Overexpression of ZEB1 and ZEB2 is associated with poor prognosis of PCa. ZEB1 and ZEB2 upregulation occurs during PCa progression and can provide therapy resistance to cancer cells. PRMT1, Smad2, and non-coding RNAs can function as upstream mediators of the ZEB family. Besides, Bax, Bcl-2, MRP1, N-cadherin and E-cadherin can be considered as downstream targets of ZEB family in PCa.

MicroRNAs as Epigenetic Determinants of Treatment Response and Potential Therapeutic Targets in Prostate Cancer

Prostate cancer (PCa) is the second most common tumor in men worldwide, and the fifth leading cause of male cancer-related deaths in western countries. PC is a very heterogeneous disease, meaning that optimal clinical management of individual patients is challenging. Depending on disease grade and stage, patients can be followed in active surveillance protocols or undergo surgery, radiotherapy, hormonal therapy, and chemotherapy. Although therapeutic advancements exist in both radiatiotherapy and chemotherapy, in a considerable proportion of patients, the treatment remains unsuccessful, mainly due to tumor poor responsiveness and/or recurrence and metastasis. microRNAs (miRNAs), small noncoding RNAs that epigenetically regulate gene expression, are essential actors in multiple tumor-related processes, including apoptosis, cell growth and proliferation, autophagy, epithelial-to-mesenchymal transition, invasion, and metastasis. Given that these processes are deeply involved in cell response to anti-cancer treatments, miRNAs have been considered as key determinants of tumor treatment response. In this review, we provide an overview on main PCa-related miRNAs and describe the biological mechanisms by which specific miRNAs concur to determine PCa response to radiation and drug therapy. Additionally, we illustrate whether miRNAs can be considered novel therapeutic targets or tools on the basis of the consequences of their expression modulation in PCa experimental models.

miR-219a-5p enhances the radiosensitivity of non-small cell lung cancer cells through targeting CD164

Lung cancer is one of the leading causes of cancer-associated mortality. Non-small cell lung carcinoma (NSCLC) accounts for 70–85% of the total cases of lung cancer. Radioresistance frequently develops in NSCLC in the middle and later stages of radiotherapy. We investigated the role of miR-219a-5p in radioresistance of NSCLC. miR-219a-5p expression in serum and lung tissue of lung cancer patients was lower than that in control. Compared with radiosensitive (RS) NSCLC patients, miR-219a-5p expression was decreased in serum and lung tissue in radioresistant patients. miR-219a-5p expression level was negatively associated with radioresistance in NSCLC cell lines. Up-regulation of miR-219a-5p increased radiosensitivity in radioresistant NSCLC cells in vitro and in vivo. Down-regulation of miR-219a-5p decreased radiosensitivity in radiosensitive A549 and H358 cells. miR-219a-5p could directly bind in the 3′UTR of CD164 and negatively regulated CD164 expression. CD164 expression was higher in radioresistant NSCLC tissues than RS tissues. Up-regulation of CD164 significantly inhibited miR-219a-5p-induced regulation of RS in radioresistant A549 and H358 cells. Down-regulation of CD164 significantly inhibited the effect of anti-miR-219a-5p on radiosensitive A549 and H358 cells. miR-219a-5p or down-regulation of CD164 could increase apoptosis and γ-H2A histone family member X (γ-H2AX) expression in radioresistant cells in vitro and in vivo. Up-regulation of CD164 could inhibit the effect of miR-219a-5p on apoptosis and γ-H2AX expression. Our results indicated that miR-219a-5p could inhibit CD164, promote DNA damage and apoptosis and enhance irradiation-induced cytotoxicity. The data highlight miR-219a-5p/CD164 pathway in the regulation of radiosensitivity in NSCLC and provide novel targets for potential intervention.

miRNAs as Therapeutic Tools and Biomarkers for Prostate Cancer

Prostate cancer (PCa) is the fifth cause of tumor-related deaths in man worldwide. Despite the considerable improvement in the clinical management of PCa, several limitations emerged both in the screening for early diagnosis and in the medical treatment. The use of prostate-specific antigen (PSA)-based screening resulted in patients’ overtreatment and the standard therapy of patients suffering from locally advanced/metastatic tumors (e.g., radical prostatectomy, radiotherapy, and androgen deprivation therapy) showed time-limited efficacy with patients undergoing progression toward the lethal metastatic castration-resistant PCa (mCRPC). Although valuable alternative therapeutic options have been recently proposed (e.g., docetaxel, cabazitaxel, abiraterone, enzalutamide, and sipuleucel-T), mCRPC remains incurable. Based on this background, there is an urgent need to identify new and more accurate prostate-specific biomarkers for PCa diagnosis and prognosis and to develop innovative medical approaches to counteract mCRPC. In this context, microRNA (miRNAs) emerged as potential biomarkers in prostate tissues and biological fluids and appeared to be promising therapeutic targets/tools for cancer therapy. Here we overview the recent literature and summarize the achievements of using miRNAs as biomarkers and therapeutic targets/tools for fighting PCa.

Differential normal skin transcriptomic response in total body irradiated mice exposed to scattered versus scanned proton beams

Proton therapy allows to avoid excess radiation dose on normal tissues. However, there are some limitations. Indeed, passive delivery of proton beams results in an increase in the lateral dose upstream of the tumor and active scanning leads to strong differences in dose delivery. This study aims to assess possible differences in the transcriptomic response of skin in C57BL/6 mice after TBI irradiation by active or passive proton beams at the dose of 6 Gy compared to unirradiated mice. In that purpose, total RNA was extracted from skin samples 3 months after irradiation and RNA-Seq was performed. Results showed that active and passive delivery lead to completely different transcription profiles. Indeed, 140 and 167 genes were differentially expressed after active and passive scanning compared to unirradiated, respectively, with only one common gene corresponding to RIKEN cDNA 9930021J03. Moreover, protein-protein interactions performed by STRING analysis showed that 31 and 25 genes are functionally related after active and passive delivery, respectively, with no common gene between both types of proton delivery. Analysis showed that active scanning led to the regulation of genes involved in skin development which was not the case with passive delivery. Moreover, 14 ncRNA were differentially regulated after active scanning against none for passive delivery. Active scanning led to 49 potential mRNA-ncRNA pairs with one ncRNA mainly involved, Gm44383 which is a miRNA. The 43 genes potentially regulated by the miRNA Gm44393 confirmed an important role of active scanning on skin keratin pathway. Our results demonstrated that there are differences in skin gene expression still 3 months after proton irradiation versus unirradiated mouse skin. And strong differences do exist in late skin gene expression between scattered or scanned proton beams. Further investigations are strongly needed to understand this discrepancy and to improve treatments by proton therapy.

Knockdown of lncRNA X inactive specific transcript (XIST) radiosensitizes non-small cell lung cancer (NSCLC) cells through regulation of miR-16-5p/WEE1 G2 checkpoint kinase (WEE1) axis

Long non-coding RNA (lncRNA) X inactive specific transcript (XIST) is reported to play an oncogenic role in non-small cell lung cancer (NSCLC). However, the role of XIST in regulating the radiosensitivity of NSCLC cells remains unclear. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expressions of XIST and miR-16-5p in NSCLC in tissues and cells, and Western blot was used to assess the expression of WEE1 G2 checkpoint kinase (WEE1). Cell counting kit-8 (CCK-8), colony formation and flow cytometry assays were used to determine cell viability and apoptosis after NSCLC cells were exposed to different doses of X-rays. The interaction between XIST and miR-16-5p was confirmed by StarBase database, qRT-PCR and dual-luciferase reporter gene assays. TargetScan database was used to predict WEE1 as a target of miR-16-5p, and their targeting relationship was further validated by Western blot, qRT-PCR and dual-luciferase reporter gene assays. XIST was highly expressed in both NSCLC tissue and cell lines, and knockdown of XIST repressed NSCLC cell viability and cell survival, and facilitated apoptosis under the irradiation. MiR-16-5p was a target of XIST, and rescue experiments demonstrated that miR-16-5p inhibitors could reverse the role of XIST knockdown on radiosensitivity in NSCLC cells. WEE1 was validated as a target gene of miR-16-5p, and WEE1 could be negatively regulated by XIST. XIST promotes the radioresistance of NSCLC cells by regulating the expressions of miR-16-5p and WEE1, which can be a novel target for NSCLC therapy.

Noncoding RNAs in the Interplay between Tumor Cells and Cancer-Associated Fibroblasts: Signals to Catch and Targets to Hit

Simple Summary

Cancer aggressiveness is the result of a proficient bidirectional interaction between tumor and stromal cells within the tumor microenvironment, among which a major role is played by the so-called cancer-associated fibroblasts. Upon such interplay, both cancer cells and fibroblasts are reprogrammed to sustain malignancy, with changes in the repertoire of noncoding RNAs, mainly microRNAs and long noncoding RNAs. Such molecules are also exchanged between the two cell types through extracellular vesicles. In this review, we summarize the current knowledge of microRNAs and long noncoding RNAs that act intracellularly or extracellularly to sustain tumor-stroma interplay. We also provide our view regarding the possible clinical utility of such noncoding RNAs as therapeutic target/tools or biomarkers to predict patient outcome or response to specific treatments.

Abstract

Cancer development and progression are not solely cell-autonomous and genetically driven processes. Dynamic interaction of cancer cells with the surrounding microenvironment, intended as the chemical/physical conditions as well as the mixture of non-neoplastic cells of the tumor niche, drive epigenetic changes that are pivotal for the acquisition of malignant traits. Cancer-associated fibroblasts (CAF), namely fibroblasts that, corrupted by cancer cells, acquire a myofibroblast-like reactive phenotype, are able to sustain tumor features by the secretion of soluble paracrine signals and the delivery extracellular vesicles. In such diabolic liaison, a major role has been ascribed to noncoding RNAs. Defined as RNAs that are functional though not being translated into proteins, noncoding RNAs predominantly act as regulators of gene expression at both the transcriptional and post-transcriptional levels. In this review, we summarize the current knowledge of microRNAs and long noncoding RNAs that act intracellularly in either CAFs or cancer cells to sustain tumor-stroma interplay. We also report on the major role of extracellular noncoding RNAs that are bidirectionally transferred between either cell type. Upon presenting a comprehensive view of the existing literature, we provide our critical opinion regarding the possible clinical utility of tumor-stroma related noncoding RNAs as therapeutic target/tools or prognostic/predictive biomarkers.

miR-541-3p enhances the radiosensitivity of prostate cancer cells by inhibiting HSP27 expression and downregulating β-catenin

Heat shock protein 27 (HSP27), a regulator of cell survival, can enhance the resistance of cancer cells to radiotherapy. As microRNA-541-3p (miR-541-3p) was recently predicted to be a putative upstream modulator of HSP27, the present study was designed to investigate the function and mechanism underlying how miR-541-3p modulates the radiosensitivity of prostate cancer (PCa) cells by regulating HSP27. Through quantitative PCR, miR-541-3p was determined to be poorly expressed in PCa tissues relative to normal controls, whereas its expression was enhanced after radiotherapy. Consistently, miR-541-3p expression levels in PCa cells were elevated after radiation. Cell viability and proliferation and apoptosis under radiation were subsequently evaluated in response to loss-of-function of miR-541-3p. It was found that inhibition of miR-541-3p facilitated the viability and proliferation of PCa cells and promoted their apoptosis post radiation, hence reducing the radiosensitivity of LNCaP cells. Dual-luciferase reporter assay identified that miR-541-3p negatively regulated the HSP27 mRNA expression by targeting its 3'-UTR. Meanwhile, miR-541-3p overexpression inhibited the β-catenin expression by targeting HSP27. Furthermore, HSP27 or β-catenin overexpression was noted to significantly reverse the miR-541-3p-mediated changes in the biological functions of PCa cells post radiation, suggesting that HSP27-dependent activation of β-catenin might be the mechanism responsible for the promotive effect of miR-541-3p on radiosensitivity. Collectively, this study suggests that miR-541-3p specifically inhibits the HSP27 expression and downregulates β-catenin, thereby enhancing the radiosensitivity of PCa cells. Our findings highlight the underlying mechanism of the miR-541-3p/HSP27/Wnt/β-catenin axis regarding radiotherapy for PCa.

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.

The effect of Jiedu Huoxue decoction on rat model of experimental nonbacterial prostatitis via regulation of miRNAs

CONTEXT

The underlying mechanisms of Jiedu Huoxue decoction (JDHXD) in treating chronic prostatitis have not been fully explored.

OBJECTIVE

This study investigates the miRNAs as potential biomarkers and the effect of JDHXD on the rat model of experimental nonbacterial prostatitis.

MATERIALS AND METHODS

Fifty-four Sprague-Dawley male rats were randomly divided into normal control, model, JDHXD low dose (0.5 g/kg/day), medium dose (1 g/kg/day), high dose (2 g/kg/day) and western medicine (cernilton 0.094 g/kg/day) groups, and intragastrically administered once daily for 30 days. The control and model (upon successful establishment) groups received distilled water. Differential expression of miRNAs was analysed with high-throughput miRNA sequencing and validated with qRT-PCR and Northern blot. Prediction of specific target genes and functional enrichment analysis were performed with bioinformatics.

RESULTS

LD₅₀ test showed no sign of toxicity with maximum feasible dose 4 g/kg JDHXD. Compared with control, 495 miRNAs showed expression changes in CAP/CPPS rats, of which 211 were significantly different and 37 were prostatic-related. There were 181 differentially expressed miRNAs between the model and high dose JDHXD groups, of which 23 were identical with the control and model groups. Compared with control, miR-146a, miR-423 and miR-205 expression increased significantly in the model group, decreased dose-dependently in the JDHXD groups (p < 0.05), and vice-versa for miR-96 (p < 0.05). The effect of low dose JDHXD was comparable to cernilton (p > 0.05).

DISCUSSION AND CONCLUSIONS

Future studies may explore the contributions of the active components in JDHXD. The study design is generalisable. The effect can be repeatedly verified in clinical trials.

The Therapeutic Potential of MicroRNAs in Cancer: Illusion or Opportunity?

The functional involvement of microRNAs in human neoplasia has raised in the last years an increasing interest in the scientific community toward the potential application in clinics as therapeutic tools. Indeed, the possibility to modulate their expression to re-establish a lost equilibrium and counteract tumor growth and dissemination, and/or to improve responsiveness to standard therapies, is promising and fascinating. However, several issues need to be taken into account such as factors related to miRNA stability in the blood, tissue penetration and potential off-target effects, which might affect safety, tolerability and efficacy of an miRNA-based therapy. Here we describe the most relevant challenges related to miRNA-based therapy, review the delivery strategies exploited to date and the on-going clinical trials.

Mechanisms of docetaxel resistance in prostate cancer: The key role played by miRNAs

One of the main problems with the treatment of metastatic prostate cancer is that, despite an initial positive response, the majority of patients develop resistance and progress. In particular, the resistance to docetaxel, the gold standard therapy for metastatic prostate cancer since 2010, represents one of the main factors responsible for the failure of prostate cancer therapy. According to the present knowledge, different processes contribute to the appearance of docetaxel resistance and non-coding RNA seems to play a relevant role in them. In this review, a comprehensive overview of the miRNA network involved in docetaxel resistance is described, highlighting the pathway/s affected by their activity.

miRNAs and radiotherapy response in prostate cancer

BACKGROUND

Gaining insight into microRNAs (miRNAs) and genes that regulate the therapeutic response of cancer diseases in general and prostate cancer (PCa) in particular is an important issue in current molecular biomedicine and allows the discovery of predictive miRNA targets.

OBJECTIVES

The aim of this study was to analyze the available data on the influence of radiotherapy (RT) on miRNA expression and on miRNA involved in radiotherapy response in PCa.

MATERIALS AND METHODS

The data used in this review were extracted from research papers and the DIANA, STRING, and other databases with a special focus on the mechanisms of radiotherapy PCa response and the miRNA involved and associated genes.

RESULTS AND DISCUSSION

A search for miRNA prognostic and therapeutic effectiveness markers should rely on both the data of recent experimental studies on the influence of RT on miRNA expression and miRNAs involved in regulation of radiosensitivity in PCa and on bioinformatics resources. miRNA panels and genes targeted by them and involved in radioresponse regulation highlighted by meta-analysis and cross-analysis of the data in the present review have.

CONCLUSION

Selected miRNA and gene panel has good potential as prognostic and radiotherapy effectiveness markers for PCa and, moreover, as radiotherapy effectiveness markers in other types of cancer, as the proposed model is not specific to PCa, which opens up opportunities for the development of a universal diagnostic system (or several intersecting systems) for oncology radiotherapy in general.

Down-regulation of lncRNA UCA1 enhances radiosensitivity in prostate cancer by suppressing EIF4G1 expression via sponging miR-331-3p

BACKGROUND

We aimed to explore the role of long noncoding RNA urothelial carcinoma-associated 1 (lncRNA UCA1) and its underlying mechanism in the radioresistance of prostate cancer (PCa).

METHODS

QRT-PCR was conducted to measure the expression of UCA1, microRNA-331-3p (miR-331-3p) and eukaryotic translation initiation factor 4 gamma 1 (EIF4G1) in PCa tissues and cells. The relative protein level was determined by western blot assay. Cell proliferation and apoptosis were detected by MTT, colony formation assay, and flow cytometry, respectively. The target interaction between miR-331-3p and UCA1 or EIF4G1 was predicted through bioinformatics analysis, and verified by dual-luciferase reporter gene assay system.

RESULTS

The high levels of UCA1 and EIF4G1 as well as the low level of miR-331-3p were observed in PCa tissues and cell lines. UCA1 and EIF4G1 expression were significantly upregulated by Gy radiation treatement. UCA1 or EIF4G1 knockdown repressed cell growth and enhanced cell apoptosis in 22RV1 and DU145 cells under radiation. Moreover, overexpression of EIF4G1 abolished UCA1 knockdown-induced effect on 6 Gy irradiated PCa cells. UCA1 sponged miR-331-3p to regulate EIF4G1 expression.

CONCLUSIONS

LncRNA UCA1 deletion suppressed the radioresistance to PCa by suppressing EIF4G1 expression via miR-331-3p. UCA1 acted as a potential regulator of radioresistance of PCa, providing a promising therapeutic target for PCa.

Ionizing Radiation-Induced Epigenetic Modifications and Their Relevance to Radiation Protection

The present system of radiation protection assumes that exposure at low doses and/or low dose-rates leads to health risks linearly related to the dose. They are evaluated by a combination of epidemiological data and radiobiological models. The latter imply that radiation induces deleterious effects via genetic mutation caused by DNA damage with a linear dose-dependence. This picture is challenged by the observation of radiation-induced epigenetic effects (changes in gene expression without altering the DNA sequence) and of non-linear responses, such as non-targeted and adaptive responses, that in turn can be controlled by gene expression networks. Here, we review important aspects of the biological response to ionizing radiation in which epigenetic mechanisms are, or could be, involved, focusing on the possible implications to the low dose issue in radiation protection. We examine in particular radiation-induced cancer, non-cancer diseases and transgenerational (hereditary) effects. We conclude that more realistic models of radiation-induced cancer should include epigenetic contribution, particularly in the initiation and progression phases, while the impact on hereditary risk evaluation is expected to be low. Epigenetic effects are also relevant in the dispute about possible "beneficial" effects at low dose and/or low dose-rate exposures, including those given by the natural background radiation.

Role of microRNAs in the development, prognosis and therapeutic response of patients with prostate cancer

Prostate cancer is the most common cancer in males in several regions. One of the major challenges in diagnosis and treatment of this cancer is how to identify men who harbor an increased risk of having clinically significant prostate cancer and how to assess response to therapy. Biomarkers, like microRNAs (miRNAs) are one of the new diagnostic/therapeutic tools for clinicians. Finding men at high risk of significant cancer is essential as they will mostly benefit from earlier diagnosis and treatment. At the same time, it is important to reduce the number of unnecessary invasive biopsies in men without (clinically significant) cancer and miRNAs have especial application in this regard. MiRNAs can regulate expression of several genes. Up to 30 percent of protein coding genes are regulated by miRNAs. Based on this critical regulatory role, miRNAs impact cell differentiation, growth and apoptosis. Several studies have reported aberrant expression of miRNAs in different cancers including prostate cancer. miRNAs are regarded as biomarkers in this kind of cancer. Moreover, expression profiles of miRNAs can predict therapeutic response to a number of drugs such docetaxel and some natural agents such as isoflavone. Functional studies have shown that miRNAs regulate a number of critical targets such as Wnt/β-catenin, PI3K/AKT, cyclin dependent kinases, VEGF and JAK/ STAT. Therefore, several aspects of prostate cancer development are influenced by miRNAs. Finally, circulating miRNAs are promising tools for assessment of prostate cancer course and prognosis. In the current review, we summarize the results of studies which reported abnormal expression of miRNAs in prostate cancer and their role as biomarkers or therapeutic targets.

Knockdown of Circ_CCNB2 Sensitizes Prostate Cancer to Radiation Through Repressing Autophagy by the miR-30b-5p/KIF18A Axis

Background: Circular RNAs (circRNAs) have recently emerged as crucial regulatory molecules in prostate cancer (PCa), but few researches focus on the effects of circRNAs on PCa radiosensitivity. The issue will be addressed in this study using circRNA Cyclin B2 (circ_CCNB2) as an object. Materials and Methods: All RNA and protein levels were severally examined using quantitative real-time polymerase chain reaction and Western blot. Colony formation assay and flow cytometry were implemented for detecting cell colony capacity and apoptotic cells, respectively. Cellular migration and invasion abilities were evaluated by transwell assay. The combination between potential target molecules was analyzed by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. The effect of circ_CCNB2 on PCa radiosensitivity in vivo was explored using xenograft models in mice. Results: Circ_CCNB2 was upregulated in irradiation-resistant PCa tissues and cells. Circ_CCNB2 knockdown had promoted effect on the radiosensitivity of irradiation-resistant PCa cells by inhibiting autophagy. Besides, circ_CCNB2 could directly sponge miR-30b-5p, and the promotion of circ_CCNB2 knockdown on PCa radiosensitivity was achieved by elevating miR-30b-5p. MiR-30b-5p enhanced the radiosensitivity of irradiation-resistant PCa cells through repressing the expression of its target kinesin family member 18A (KIF18A). Furthermore, circ_CCNB2 regulated the KIF18A level through targeting miR-30b-5p. Circ_CCNB2 downregulation facilitated PCa radiosensitivity in vivo through inhibiting autophagy by miR-30b-5p/KIF18A. Conclusions: In this study, knockdown of circ_CCNB2 was shown to promote PCa radiosensitivity through autophagy repression by miR-30b-5p/KIF18A axis, developing a molecular resistance mechanism of PCa radiotherapy and a feasible strategy to increase radiosensitivity.

MicroRNAs and Their Influence on the ZEB Family: Mechanistic Aspects and Therapeutic Applications in Cancer Therapy

Molecular signaling pathways involved in cancer have been intensively studied due to their crucial role in cancer cell growth and dissemination. Among them, zinc finger E-box binding homeobox-1 (ZEB1) and -2 (ZEB2) are molecules that play vital roles in signaling pathways to ensure the survival of tumor cells, particularly through enhancing cell proliferation, promoting cell migration and invasion, and triggering drug resistance. Importantly, ZEB proteins are regulated by microRNAs (miRs). In this review, we demonstrate the impact that miRs have on cancer therapy, through their targeting of ZEB proteins. MiRs are able to act as onco-suppressor factors and inhibit the malignancy of tumor cells through ZEB1/2 down-regulation. This can lead to an inhibition of epithelial-mesenchymal transition (EMT) mechanism, therefore reducing metastasis. Additionally, miRs are able to inhibit ZEB1/2-mediated drug resistance and immunosuppression. Additionally, we explore the upstream modulators of miRs such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), as these regulators can influence the inhibitory effect of miRs on ZEB proteins and cancer progression.

Coordinated AR and microRNA regulation in prostate cancer

The androgen receptor (AR) remains a key driver of prostate cancer (PCa) progression, even in the advanced castrate-resistant stage, where testicular androgens are absent. It is therefore of critical importance to understand the molecular mechanisms governing its activity and regulation during prostate tumourigenesis. MicroRNAs (miRs) are small ∼22 nt non-coding RNAs that regulate target gene, often through association with 3′ untranslated regions (3′UTRs) of transcripts. They display dysregulation during cancer progression, can function as oncogenes or tumour suppressors, and are increasingly recognised as targets or regulators of hormonal action. Thus, understanding factors which modulate miRs synthesis is essential. There is increasing evidence for complex and dynamic bi-directional cross-talk between the multi-step miR biogenesis cascade and the AR signalling axis in PCa. This review summarises the wealth of mechanisms by which miRs are regulated by AR, and conversely, how miRs impact AR's transcriptional activity, including that of AR splice variants. In addition, we assess the implications of the convergence of these pathways on the clinical employment of miRs as PCa biomarkers and therapeutic targets.

SPOP Deregulation Improves the Radiation Response of Prostate Cancer Models by Impairing DNA Damage Repair

Speckle-type POZ (pox virus and zinc finger protein) protein (SPOP) is the most commonly mutated gene in prostate cancer (PCa). Recent evidence reports a role of SPOP in DNA damage response (DDR), indicating a possible impact of SPOP deregulation on PCa radiosensitivity. This study aimed to define the role of SPOP deregulation (by gene mutation or knockdown) as a radiosensitizing factor in PCa preclinical models. To express WT or mutant (Y87N, K129E and F133V) SPOP, DU145 and PC-3 cells were transfected with pMCV6 vectors. Sensitivity profiles were assessed using clonogenic assay and immunofluorescent staining of γH2AX and RAD51 foci. SCID xenografts were treated with 5 Gy single dose irradiation using an image-guided small animal irradiator. siRNA and miRNA mimics were used to silence SPOP or express the SPOP negative regulator miR-145, respectively. SPOP deregulation, by either gene mutation or knockdown, consistently enhanced the radiation response of PCa models by impairing DDR, as indicated by transcriptome analysis and functionally confirmed by decreased RAD51 foci. SPOP silencing also resulted in a significant downregulation of RAD51 and CHK1 expression, consistent with the impairment of homologous recombination. Our results indicate that SPOP deregulation plays a radiosensitizing role in PCa by impairing DDR via downregulation of RAD51 and CHK1.

Identifying Long Non-coding RNA of Prostate Cancer Associated With Radioresponse by Comprehensive Bioinformatics Analysis

Although radiotherapy is greatly successful in the treatment of prostate cancer (PCa), radioresistance is still a major challenge in the treatment. To our knowledge, this study is the first to screen long non-coding RNAs (lncRNAs) associated with radioresponse in PCa by The Cancer Genome Atlas (TCGA). Bioinformatics methods were used to identify the differentially expressed lncRNAs and protein-coding genes (PCGs) between complete response (CR) and non-complete response (non-CR) groups in radiotherapy. Statistical methods were applied to identify the correlation between lncRNAs and radioresponse as well as lncRNAs and PCGs. The correlation between PCGs and radioresponse was analyzed using weighted gene co-expression network analysis (WGCNA). The three online databases were used to predict the potential target miRNAs of lncRNAs and the miRNAs that might regulate PCGs. RT-qPCR was utilized to detect the expression of lncRNAs and PCGs in our PCa patients. A total of 65 differentially expressed lncRNAs and 468 differentially expressed PCGs were found between the two groups of PCa. After the chi-square test, LINC01600 was selected to be highly correlated with radioresponse from the 65 differentially expressed lncRNAs. Pearson correlation analysis found 558 PCGs co-expressed with LINC01600. WGCNA identified the darkred module associated with radioresponse in PCa. After taking the intersection of the darkred module of WGCNA, differentially expressed PCGs between the two groups of PCa, and the PCGs co-expressed with LINC01600, three PCGs, that is, JUND, ZFP36, and ATF3 were identified as the potential target PCGs of LINC01600. More importantly, we detected the expression of LINC01600 and three PCGs using our PCa patients, and finally verified that LINC01600 and JUND were differentially expressed between CR and non-CR groups, excluding ZFP36 and ATF3. Meantime, the potential regulation ability of LINC01600 for JUND in PCa cell lines was initially explored. In addition, we constructed the competing endogenous RNA (ceRNA) network of LINC01600—miRNA—JUND. In conclusion, we initially reveal the association of LINC01600 with radioresponse in PCa and identify its potential target PCGs for further basic and clinical research.

MiRNAs in Radiotherapy Resistance of Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is one of the most common malignant tumors of the head and neck in Southeast Asia and southern China. Although the comprehensive treatment based on intensity-modulated radiation therapy improves outcomes, the five-year survival rate of NPC patients is low, and the recurrence remains high. Radiotherapy resistance is the main cause of poor prognosis in NPC patients. MicroRNAs (miRNAs) are a class of endogenous non-coding RNAs regulating various biological functions in eukaryotes. These miRNAs can regulate the development and progression of nasopharyngeal carcinoma by affecting the proliferation, apoptosis, movement, invasion and metastasis of NPC cells. The abnormal expression of miRNAs is closely related to radiotherapy sensitivity and prognosis of NPC patients, which can affect the transmission of related signaling pathways by regulating the expression of tumor suppressor genes and / or oncogenes, and therefore participate in radiotherapy resistance in nasopharyngeal carcinoma. Here, we review the mechanisms by which miRNAs may be involved in the radiotherapy resistance of nasopharyngeal carcinoma.

microRNAs identified in prostate cancer: Correlative studies on response to ionizing radiation

As the most frequently diagnosed non-skin cancer in men and a leading cause of cancer-related death, understanding the molecular mechanisms that drive treatment resistance in prostate cancer poses a significant clinical need. Radiotherapy is one of the most widely used treatments for prostate cancer, along with surgery, hormone therapy, and chemotherapy. However, inherent radioresistance of tumor cells can reduce local control and ultimately lead to poor patient outcomes, such as recurrence, metastasis and death. The underlying mechanisms of radioresistance have not been fully elucidated, but it has been suggested that miRNAs play a critical role. miRNAs are small non-coding RNAs that regulate gene expression in every signaling pathway of the cell, with one miRNA often having multiple targets. By fine-tuning gene expression, miRNAs are important players in modulating DNA damage response, cell death, tumor aggression and the tumor microenvironment, and can ultimately affect a tumor’s response to radiotherapy. Furthermore, much interest has focused on miRNAs found in biofluids and their potential utility in various clinical applications. In this review, we summarize the current knowledge on miRNA deregulation after irradiation and the associated functional outcomes, with a focus on prostate cancer. In addition, we discuss the utility of circulating miRNAs as non-invasive biomarkers to diagnose, predict response to treatment, and prognosticate patient outcomes.

ZEB1: A Critical Regulator of Cell Plasticity, DNA Damage Response, and Therapy Resistance

The predominant way in which conventional chemotherapy kills rapidly proliferating cancer cells is the induction of DNA damage. However, chemoresistance remains the main obstacle to therapy effectivity. An increasing number of studies suggest that epithelial-to-mesenchymal transition (EMT) represents a critical process affecting the sensitivity of cancer cells to chemotherapy. Zinc finger E-box binding homeobox 1 (ZEB1) is a prime element of a network of transcription factors controlling EMT and has been identified as an important molecule in the regulation of DNA damage, cancer cell differentiation, and metastasis. Recent studies have considered upregulation of ZEB1 as a potential modulator of chemoresistance. It has been hypothesized that cancer cells undergoing EMT acquire unique properties that resemble those of cancer stem cells (CSCs). These stem-like cells manifest enhanced DNA damage response (DDR) and DNA repair capacity, self-renewal, or chemoresistance. In contrast, functional experiments have shown that ZEB1 induces chemoresistance regardless of whether other EMT-related changes occur. ZEB1 has also been identified as an important regulator of DDR by the formation of a ZEB1/p300/PCAF complex and direct interaction with ATM kinase, which has been linked to radioresistance. Moreover, ATM can directly phosphorylate ZEB1 and enhance its stability. Downregulation of ZEB1 has also been shown to reduce the abundance of CHK1, an effector kinase of DDR activated by ATR, and to induce its ubiquitin-dependent degradation. In this perspective, we focus on the role of ZEB1 in the regulation of DDR and describe the mechanisms of ZEB1-dependent chemoresistance.

Knockdown of lncRNA TUG1 Enhances Radiosensitivity of Prostate Cancer via the TUG1/miR-139-5p/SMC1A Axis

Background

Prostate cancer (PCa) is a common malignant tumor of the urinary system in males. LncRNA taurine-upregulated gene 1 (TUG1) has been verified to play a crucial role in progression and prognosis of PCa. However, the functional mechanism of TUG1 remains unclear with radiosensitivity of PCa.

Methods

Quantitative real-time PCR (qRT-PCR) was conducted to measure the transcription levels of genes. 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and flow cytometry analysis were employed to assess cell proliferation and apoptosis, respectively. Moreover, colony formation assay was used to measure colony survival. Western blot was performed to detect the relative proteins expression. The interaction among variables was predicted by online tool starbase, and then confirmed using the dual luciferase reporter assay. A xenograft mouse model was constructed to investigate the effect of TUG1 on tumor growth in vivo.

Results

The levels of lncRNA TUG1 and SMC1A were remarkably increased, while miR-139-5p was downregulated in PCa. Patients with high expression of TUG1 showed a lower survival rate and poor prognosis. Knockdown of TUG1 inhibited PCa cell proliferation and colony survival fraction, and promoted apoptosis. Downregulation of miR-139-5p reversed the effects of TUG1 deletion on proliferation, apoptosis and colony survival fraction in PCa cells treated with 4 Gy of X-ray radiation. Moreover, TUG1 sponged miR-139-5p to regulate SMC1A expression. SMC1A deletion blocked the effects of TUG1 on the progression of PCa cells treated with 4 Gy of X-ray radiation. The tumor volume and weight were illustriously reduced with radiation and TUG1 silencing in xenograft model.

Conclusion

Knockdown of lncRNA TUG1 enhanced radiosensitivity in PCa via the TUG1/miR-139-5p/SMC1A axis. It may become a promising target for PCa treatment.

Role of non-coding RNAs and RNA modifiers in cancer therapy resistance

As the standard treatments for cancer, chemotherapy and radiotherapy have been widely applied to clinical practice worldwide. However, the resistance to cancer therapies is a major challenge in clinics and scientific research, resulting in tumor recurrence and metastasis. The mechanisms of therapy resistance are complicated and result from multiple factors. Among them, non-coding RNAs (ncRNAs), along with their modifiers, have been investigated to play key roles in regulating tumor development and mediating therapy resistance within various cancers, such as hepatocellular carcinoma, breast cancer, lung cancer, gastric cancer, etc. In this review, we attempt to elucidate the mechanisms underlying ncRNA/modifier-modulated resistance to chemotherapy and radiotherapy, providing some therapeutic potential points for future cancer treatment.

miR-1272 Exerts Tumor-Suppressive Functions in Prostate Cancer via HIP1 Suppression

The development of novel therapies or the improvement of currently used approaches to treat prostate cancer (PCa), the most frequently diagnosed male tumor in developed countries, is an urgent need. In this regard, the functional characterization of microRNAs, molecules shown to regulate a number of cancer-related pathways, is instrumental to their possible clinical exploitation. Here, we demonstrate the tumor-suppressive role of the so far uncharacterized miR-1272, which we found to be significantly down-modulated in PCa clinical specimens compared to normal tissues. Through a gain-of-function approach using miRNA mimics, we showed that miR-1272 supplementation in two PCa cell models (DU145 and 22Rv1) reverted the mesenchymal phenotype by affecting migratory and invasive properties, and reduced cell growth in vitro and in vivo in SCID mice. Additionally, by targeting HIP1 encoding the endocytic protein HIP1, miR-1272 balanced EGFR membrane turnover, thus affecting the downstream AKT/ERK pathways, and, ultimately, increasing PCa cell response to ionizing radiation. Overall, our results show that miR-1272 reconstitution can affect several tumor traits, thus suggesting this approach as a potential novel therapeutic strategy to be pursued for PCa, with the multiple aim of reducing tumor growth, enhancing response to radiotherapy and limiting metastatic dissemination.

MicroRNA-Based Combinatorial Cancer Therapy: Effects of MicroRNAs on the Efficacy of Anti-Cancer Therapies

The susceptibility of cancer cells to different types of treatments can be restricted by intrinsic and acquired therapeutic resistance, leading to the failure of cancer regression and remission. To overcome this problem, a combination therapy has been proposed as a fundamental strategy to improve therapeutic responses; however, resistance is still unavoidable. MicroRNA (miRNAs) are associated with cancer therapeutic resistance. The modulation of dysregulated miRNA levels through miRNA-based therapy comprising a replacement or inhibition approach has been proposed to sensitize cancer cells to other anti-cancer therapies. The combination of miRNA-based therapy with other anti-cancer therapies (miRNA-based combinatorial cancer therapy) is attractive, due to the ability of miRNAs to target multiple genes associated with the signaling pathways controlling therapeutic resistance. In this article, we present an overview of recent findings on the role of therapeutic resistance-related miRNAs in different types of cancer. We review the feasibility of utilizing dysregulated miRNAs in cancer cells and extracellular vesicles as potential candidates for miRNA-based combinatorial cancer therapy. We also discuss innate properties of miRNAs that need to be considered for more effective combinatorial cancer therapy.